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A Laboratory Studyon the use of Waxes toReduce Paving Temperatures

H.Soenen1, T.Tanghe1, P.Redelius1,J. De Visscher2, F.Vervaecke2, A.Vanelstraete2

1Nynas Bitumen AB, Noorderlaan, Belgium,2Belgian Road Research Centre, Woluwedal, Belgium

There is considerable interest in the possibilities of producing and paving asphalt at reduced temperature. A reduction of thetemperature generates a significant reduction in energy consumption, emissions and fumes. Also health and safety conditions forthe road workers are improved.

This paper presents the first results of a common research project of Nynas and BRRC, in which three techniques for reducingproduction temperatures are considered: the addition of waxes as viscosity reducers, the addition of zeolites as foaming agentand the use of foamed bitumen. The first phase of the project aims at developing laboratory procedures for assessing the potentialof each technique to reduce the production temperature. If the mix undergoes curing after compaction, procedures to simulateand possibly accelerate the curing process also need to be developed. Small field trials are planned to validate the outcome of thelaboratory work. In a second phase, the performance of the mixes produced at reduced temperature will be evaluated andcompared to standard hot mix asphalt, since requirements on asphalt performance (including stiffness, durability, resistance topermanent deformation and cracking) have to be fulfilled. Test sections are planned in a third phase, to extrapolate and validatethe laboratory results by field data and experience. This paper describes the first phase results of the technique using waxes asviscosity reducers.

Traditionally, asphalt mixtures are produced and laid

respectively at temperatures between 180 and 150°C.

These high temperatures are needed to achieve a low

viscosity of the bitumen which facilitates a complete and

strong coating of the aggregates and which allows a good

workability and compactability of the asphalt mixture. In

the asphalt industry there is interest in exploring the

possibilities of producing and paving asphalt mixtures at

lower temperatures (80-120°C), the advantages of

producing at lower temperatures are obvious, including

reduced energy consumption, reduced emissions and

fumes, improved health and safety conditions for the road

workers.

Several processes are available to reduce the mixing and

compaction temperature of hot mix asphalt, one of these

processes uses waxes to reduce the viscosity of the

bituminous binder in the high temperature range (1-4). In

order to be efficient, this wax should be solid at the highest

service temperature, but at temperatures above the

highest service temperature the wax should melt, become

liquid, lower the viscosity of the mixture and in this way

should allow production and compaction of asphalt mixes

at reduced temperatures. Literature shows that waxes

with a melting range between 100°C and 145°C have been

used as viscosity reducers. According to the producers

of these waxes, a temperature reduction of 30°C can be

achieved compared to standard hot mix applications.

Apart from their ability to reduce the production

temperature, these waxes are also promoted as

performance improvers for rutting (5, 6). In this paper a

laboratory study is presented with the aim to evaluate the

potential of various commercially available waxes to

reduce the production temperature of asphalt mixtures.

In addition, this study aims at providing quantitative

information on the range of temperature reduction that

can be expected as well as on the amount of wax that

Research Paving Temperatures

www.masterbuilder.co.in • The Masterbuilder - February 2012 67

needs to be added. The possible potential of waxes to

improve the resistance to permanent deformation is also

evaluated. The paper is subdivided into two parts: First,

tests on the as-received waxes and on the bitumen-wax

blends are discussed, afterwards, tests on asphalt mixes

are described.

This paper belongs to a larger project between Nynas

and BRRC in which three techniques for reducing

production temperatures are considered: the addition of

waxes as viscosity reducers, the addition of zeolites as

foaming agents and the use of foamed bitumen. The first

phase results of the technique using zeolites are

presented in reference 14.

Tests on Waxes and Bitumen-Wax Blends

Materials

Ten commercial waxes were collected, denoted

alphabetically from A to J. The bituminous reference

binder is a paving grade bitumen 50/70. The temperature

reduction potential, as well as the performance related

properties of the wax modified bitumen (WMB), are

compared to this reference binder. WMBs were prepared

by adding the wax pellets to hot bitumen and by continued

blending at 160°C for 1 hour. Two experimental methods

were used, Differential Scanning Calorimetry (DSC) and

Dynamic Shear Rheology (DSR). The DSC equipment was

a TA instruments 2920 Modulated DSC. The DSR

equipment was a Paar Physica MCR500, with the 8 mm

and 25 mm plates. For the high temperature

measurements, a Paar Physica MCR101 equipment was

used with a cup-cylinder geometry.

Investigations on the as-received waxes

Differential scanning calorimetry (DSC) was used to

investigate the melting and crystallization behaviour of

the pure waxes. The samples were first cooled from 180°C

to -70°C at -10°C/min and subsequently heated at the

same heating rate. Cooling scans are presented in Figure

1. Crystallization, in most cases observed during cooling,

can be followed as an exothermal signal; melting is

observed in the heating scan as an endothermal signal;

and a glass transition is observed as a shift in the baseline.

The surface of the endo- and exothermal signals,

calculated as an enthalpy, gives an indication of the

amount of crystall izing material. Some important

parameters are represented in table 1: the temperature

where crystallization starts on cooling (Tc-onset), the

temperature where melting starts on heating (Tmonset)

and the enthalpy of the crystallization signal on cooling. If

more than one signal is observed, the values for the smaller

signal are placed between brackets.

From the DSC behaviour the samples can be subdivided

into five types: In figure 1, an example of each type is

shown.

- Wax-A, Wax-B and Wax-C, show a large and sharp

crystallization signal on cooling, starting at 140°C,

followed by various very small crystallization peaks at

lower temperatures. These three samples behave very

similar.

- Wax-D shows a large and sharp crystallization onset,

starting at 112°C, but the exothermal signal broadens

somewhat at lower temperatures with an end-

crystallization temperature at around 60°C.

- Wax-E shows a large crystallization signal, starting at

102°C and ending around 60°C.

- For Wax F and Wax-G the shape of the crystallization

signal is very similar to Wax-E, but for these samples

the sharp crystallization signal, at high temperature

(around 105°C) is small and is combined with a large

signal that covers a very broad temperature range,

extending to temperatures below 20°C. In these

Samples

Ref. bitumen

Wax-A

Wax-B

Wax-C

Wax-D

Wax-E

Wax-F

Wax-G

Wax-I

Wax-J

Wax-H

Tc-onset CoolingA

(°C)

-

140-(75)

140-(70)

140-(70)

110

100

100

100

47

36

(120)-80

Tm-onsetHeatingA (°C)

-

(65)-125

(67)-120

(60)-120

60

60

30

45

57

45

86-(100)

ÄH CoolingB

(J/g)

-

127

139

141

268

247

226

234

27

20

47

Viscosity at 150°C(20s-1) (Pa.s)

2.14E-01

8.79E-03

7.90E-03

8.42E-03

5.43E-02

8.35E-03

4.05E-02

1.07E-02

2.54E-01

3.37E-01

7.26E-03

Temp. of viscosityincrease (°C)

-

143.0

142.5

144.4

114.2

101.0

105.7

104.5

-

-

-

Remarks

Broad crystallization range

Low degree of crystallinity

A if more than one signal, the smallest signal is placed between brackets, B only the value for the largest signal is givenTable 1: Calorimetric and viscosity properties of the as-received waxes and of the reference binder B50/70.

Research Paving Temperatures

The Masterbuilder - February 2012 • www.masterbuilder.co.in68

samples a lot of material still has to crystallize at

temperatures below 60°C, and this could cause

problems at high service temperatures if these

samples are to be used in asphalt mixes.

- Wax-H, Wax-I, Wax-J show only very small

crystallization signals, seen as small peaks, and have

at lower temperatures, below 0°C, a shift in baseline

related to a glass transition (this is not shown in Figure

1). The crystallinity of these three samples is very low,

therefore these waxes will soften the binder at all

temperatures, also at high service temperatures, and

this can cause problems.

Viscosities of the as-received waxes could be

investigated, at least in the molten state, using a bob-

cylinder type rheometer in rotational mode. Dynamic

viscosities were measured during cooling from 180°C to

80°C at a cooling rate of -2°C/min. Some cooling scans

are shown in figure 2, together with a scan of the reference

binder. The sharp increase in viscosity of these samples

is caused by the crystallization onset. At this point, the

measurements had to be stopped because the samples

became too stiff to be measured in a bob-cylinder

geometry. In table 1 some viscosity parameters, such as

the temperature where the viscosity increases as well as

Figure 1: DSC cooling scans (-10°C/min) of pure waxes

Figure 2: Dynamic viscosities of reference binder B55 and pure waxes (shear rate20/s, cooling rate -2°C/min).

the level of viscosity at 150°C are included.

The level of the viscosity at 150°C is for most waxes below

the viscosity of the reference bituminous binder. In order

to achieve a viscosity reduction of the reference binder

by adding waxes this is of course a necessary condition.

Tests on bitumen-wax blends at productiontemperatures

Similar tests were done on the waxes blended with the

B50/70 reference binder, in a concentration of 3% wax. As

this concentration is recommended by wax producers it

was used as a starting point. DSC cooling scans are shown

in figure 3. Compared to the pure waxes the bitumen -

wax blends show a considerable decrease in

crystallization temperatures, which indicates some

interaction of the wax with the binder. For example, for

Wax-A there is a temperature drop of about 40°C between

the crystallization onset in the pure and in the blended

form. For Wax-D this drop is about 20°C. The waxes (H, I,

J) which showed small crystallization signals in the pure

form did not show any exothermal signal anymore in the

3% blends. In table 2, some parameters for the blends

are summarized.

Viscosities of the 3% Wax Modified Bitumen (WMB), with

the reference binder B55 as base binder, were

investigated at temperatures between 160°C and 60°C,

see figure 4. As for the pure waxes, the crystallization of

the wax results in a sharp increase in viscosity, and again

a sometimes large temperature depression between the

pure and the WMB was observed. Although most of the

pure waxes have a lower viscosity than the reference

binder in this temperature range, the viscosity reduction

in the 3% WMBs is rather limited, especially if this decrease

in viscosity is expressed as a shift in temperature. Equi-

viscous temperatures are included in table 2. Compared

to the reference binder the temperature shift is limited to

a maximum of 6°C. Since the viscosity reduction for 3%

Figure 3: DSC cooling scans of 3% WMBs , compared to the reference binder(cooling rate -10°C/min)

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blends is limited, higher concentrations of wax in bitumen

were investigated; but even for 5% WMBs the reduction

in viscosity was still limited.

Samples

Ref. binder

Wax-A

Wax-B

Wax-C

Wax-D

Wax-E

Wax-F

Wax-G

Wax-I

Wax-J

Wax-H

DSC Tconset

cooling (°C)

-

101

102

102

93

77

76

81

-

-

-

Temp.viscosity

increase (°C)

-

94

96

96

93

79

78

80

-

-

-

Viscosity at150°C (20s-1)

(Pa.s)

0.214

0.160

0.163

0.169

0.175

0.166

0.168

0.160

0.210

0.218

0.162

Equivisc.temp.

for 1Pa.s (°C)

120

114

116.5

116

115

114

114

112

119

120

114

Table 2: Calorimetric and viscosity properties of 3% WMBs and of the referencebinder.

Figure 4: Complex viscosity during cooling for various 3% WMBs and for thereference binder (cooling rate - 2°C/min; 1Hz, 1% strain)

Another parameter that can be varied is the penetration

level of the base binder. Using a softer binder results in a

larger viscosity reduction, but this can of course only be

used if the stiffness at high service temperatures is not

negatively influenced. Performance-related tests at

service temperatures will be discussed in detail in the

next section. The effect on viscosity of using more wax or

a softer base grade bitumen is given in table 3. For

example, the reduction in viscosity is largest after adding

5% of wax (E, in this case) to a base binder with a

penetration of 180 mm/10 and corresponds to a

temperature shift of about 25°C.

Tests on bitumen-wax blends at service temperatures

In this section, performance-related binder tests were

conducted on several 3% WMBs using the reference

binder B55 as base binder. Conventional tests are shown

in table 4. From table 4 it is clear that the three waxes that

showed only small signals in the DSC tests (Wax-I, Wax-J

and Wax-H) also show a very limited increase in R&B

temperature. For the two waxes with a very broad DSC

signal (Wax-F and G) only Wax-G shows a considerable

increase in softening point while the other sample, Wax-F,

shows an increase of only 10°C. The other waxes all show

large increases in softening point.

The waxes with a considerable increase in softening point

were considered in DSR testing. Frequency sweeps were

made from -10°C to +90°C, in order to have an idea of the

low temperature performance and also the high service

temperature performance. For the low temperature

performance the stiffness at 1Hz and 0°C is included in

table 4. One can observe that this stiffness level is never

increased by more than 5% which at least indicates that

the low temperature stiffness is almost not influenced by

adding 3% of wax to the base binder. For Wax-E, F and G

the low temperature stiffness is even slightly decreased.

To assess the rutting susceptibility, two parameters are

included in table 4: the SHRP high temperature

Performance Grading (PG), measured on the original

binder at a frequency of 1.59 Hz, and a low frequency

parameter measured at 50°C. It can be observed that the

PG temperature can increase by 16°C, just by adding 3%

of, for example Wax-C, to the base binder. A low frequency

parameter is also given in table 4, since in reference 7 it

was observed that the relation between experimentally

measured rut depths and binder stiffness levels improved

if the frequency was reduced to 0.01Hz. The low frequency

stiffness at 50°C is increased for all the waxes added, in

Pen Base bindermm/10

55 (ref.binder)

55

Wax type andconcentration

-

+ 2% Wax-B

+ 3% Wax B

+ 4% Wax B

+ 2% Wax-D

+ 3% Wax-D

+ 4% Wax-D

Temp. viscosity1Pa.s, (°C)

120

117.5

116.5

115.5

117

115

114

Pen Base bindermm/10

80

100

180

Wax type andconcentration

+ 2% Wax E

+ 3% Wax E

+ 4% Wax E

+ 5% Wax E

+ 3% Wax E

+ 4% Wax E

+ 5% Wax E

Temp. viscosity1Pa.s (°C)

111

109

107

102

99

98

96

Table 3: Influence of wax concentration and base binder penetration on the viscosity properties of WMBs.

Research Paving Temperatures

www.masterbuilder.co.in • The Masterbuilder - February 2012 71

some cases the increase is more than a decade. A change

of one decade can be compared to a change from a base

binder pen 50/70 to a base binder pen 10/20.

There are large differences in stiffening effect at 50°C

between the different wax types. Those waxes which show

sufficient crystalline material in the DSC cooling scan,

that crystallizes at high enough temperatures (above 60°C)

show the largest stiffening effects. So in practice those

waxes with a large exotherm occurring over a small and

high temperature range seem to be most suited to

improve the resistance against rutting .

Upon analyzing the DSR behaviour in detail it was

observed that the stiffness of wax modified binders is very

strain sensitive, the stiffness reduces very quickly if the

applied torque level increases. The authors have also

shown this in reference 8. In figure 5 stress sweeps,

recorded at 50°C and at 0.01Hz, on some selected

samples are shown. Compared to unmodified and

polymer modified binders, these WMBs can be

considered as strain sensitive binders. The finding that

WMBs are much more strain sensitive than unmodified or

polymer modified binders at high service temperature is

very important. In literature, there is a lot of discussion if

performance indicators for rutting should be measured

inside or outside the linear viscoselastic (LVE) range (9,

10). For unmodified and polymer modified binders the

LVE range is rather large and the question is not so crucial,

but for these WMBs the LVE range is limited to low strain

levels, and maybe not representative of the strain and

stress level(s) the binder feels when loaded in an asphalt

layer in a road. For the time being it is not clear what

stress or strain level should be used in binder tests and

how this relates to a stress or strain level in asphalt mix

tests. In reference 11 a value of 300% strain is suggested,

but this depends on many factors, such as thickness of

the binder film, void content and aggregate grading. In

the section on asphalt mix tests some experimental rut

measurements on waxy samples, loaded in an MLPC rut

Samples

Ref. bitumen

Wax-A

Wax-B

Wax-C

Wax-D

Wax-E

Wax-F

Wax-G

Wax-H

Wax-I

Wax-J

Pen 25°C (mm/10)

55

45

42

43

40

35

53

40

49

53

56

R&B (°C)

49.0

100.6

93.3

100.5

102.0

78.9

59.4

90.0

52.7

50.0

55.5

Temp.G*/sin(ä) = 1kPa,1.59 Hz, 1% strain (°C)

68

79

82

84

79

76

70

72

G*/sin(ä)- 0.01Hz &50°C 1% strain (Pa)

1.13E+02

8.49E+02

10.26E+02

15.04E+02

6.63E+02

5.85E+02

1.39E+02

2.46E+02

G* - 1Hz - 0°C 0.05%strain (Pa)

9.85E+07

1.02E+08

1.03E+08

1.07E+08

1.12E+08

7.77E+07

7.58E+07

9.32E+07

Table 4: Conventional and rheological properties of the reference binder and various WMBs. All blends consist of 3% of the respective wax in the B50/70 ref . binder.

tester at 50°C will be discussed and related to the binder

tests.

Figure 5: Strain dependency at 50°C and 0.01Hz of some selected WMBs, somePMBs and some unmodified binders.

Proposed system to select base binder andconcentration of wax

In the previous sections, general properties of various

waxes and WMBs were presented. In table 3, it was shown

that the viscosity reduction for a specific wax and bitumen

blend is dependent on the wax concentration and the

penetration level of the base binder. In this section a

method to estimate the reduction in temperature for one

selected wax material (wax-E) is given.

The viscosities of several WMBs with wax-E at three

different concentrations and with base binders with

different penetration levels, were tested and the

temperature where the viscosity has a certain value, in

this case 1Pa.s, is plotted versus the penetration level of

the base binder (see figure 6). If we assume that

compactability is related to the viscosity of the binder, an

assumption that is often used in literature for unmodified

(12) and for modified binders (13), this figure can be used

to see how a temperature reduction of 20°C, based on

equi-viscosity levels, can be achieved. Several options

exist: If 5% of wax is used it would be sufficient to use a

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The Masterbuilder - February 2012 • www.masterbuilder.co.in72

softer base binder with a pen. level of around 125, if 4% of

wax is added a pen base binder of 155 should be used,

and if this needs to be achieved with only 3% of wax a

base binder of pen 170 needs to be used. Of course,

before using a base binder with a penetration of 170, one

should also consider performance related parameters,

as is further discussed below.

Regarding performance, the rutting sensitivity isconsidered as the most critical parameter, certainly if the

penetration level of the base binder would be increased

in order to get sufficient temperature reduction. In this

study, the stiffness at 50°C and at a frequency of 0.01Hz is

used as a binder performance indicator for rutting, since

in a previous study it was found that this parameter is a

good performance indicator for unmodified and also

polymer modified binders (7). In figure 7 the level of

stiffness (at 50°C and 0.01Hz), measured inside the LVE

range is plotted for the base binders and various binder-

wax blends. From this figure, it is clear that the stiffness of

the reference binder (a value around 100Pa) is reached

for all the WMBs, so this graphs would indicate that wax-

E is excellent to improve the rutting resistance and also

Figure 6: Equi-viscosity temperatures as a function of penetration level of the basebinder

that a soft base binder (even a pen 180) could be used

and would give sufficient rutting resistance. In figure 8 a

similar graph is shown but now the stiffness level is

measured at a much higher strain level, in this case 300%

strain is used since this value is indicated in literature.

Figure 8 illustrates that, in order to have the same range

of stiffness as the reference binder, a base binder pen

180 could be used, provided 5% of wax is added. If only

3% of wax would be used, the penetration level of the

base binder should not be higher than 140. Of course

these conclusions are based on the assumption that the

strain level of 300% (at 50°C and at 0.01Hz) is

representative for the strain the binder experiences when

loaded in a mix, an assumption which is not yet validated.

Conclusions

In the previous section, a system was proposed to select

the base binder and the wax concentration with the aim

of achieving a given reduction in asphalt production

temperatures. This system is based on, several

assumptions:

- The reduction in temperature of compaction and

paving is entirely related to the viscosity of the binder.

Therefore, equi-viscosity temperatures measured on

the binder-wax combinations can be used to predict

the achievable reduction in asphalt production

temperatures.

- The wax is compatible with the bitumen, so that there

is no separate phase of nearly pure wax which could

then keep its low viscosity. This assumption is in fact

already validated by the viscosity tests on the WMBs

described in the previous sections. The viscosity of a

WMB relates very well to values that are expected for

a compatible blend based on the viscosities of the 2

pure components.

- Regarding rutting sensitivity, the assumption is made

that binders with equal stiffness at 50°C, at 0.01HzFigure 7: Stiffness at 50°C and 0.01Hz within linear visco-elastic range versuspenetration of the base binder.

Figure 8: Stiffness at 50°C and 0.01Hz at 300% strain level versus penetration of thebase binder.

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and at 300% strain will have similar rutting resistance.

This assumption is based on a rough estimation found

in literature, that the strain level of the binder in a mix,

if loaded at high temperature, can achieve strain levels

of 300%. Of course this strain level will depend on the

mix type, in particular on the amount of binder, the

thickness of the binder fi lm, the void content,

angularity of aggregates, amount of coarse material,

etc.

In the following section, these assumptions will be verified

by asphalt mix tests.

Asphalt Mix Tests

Mix Design

The study was made with a mix type AB-4C, which is

specified in the standard specifications of the Flemish

region (SB 250 v2.1). This is an asphalt concrete mix for

top layers, AC 0/10 according to the European standards.

Use was made of the PradoWin software of BRRC. With

the characteristics of the different constituents as input

data, this software predicts the volumetric composition

and void content of the mix for a given mix composition.

Table 5 shows the dry mix composition. The grading of

the mix is shown in figure 9. The binder is added in 6.2 %

by mass on the aggregate mass (5.84 % by mass in the

mix). The same mix design was used for the reference

Type

Fillers

Coarse

Aggregates

Coarse

Aggregates

Coarse

Aggregates

Sand

Sand

Component

Duras II

porphyry 4/6.3

porphyry 2/4

porphyry 6.3/10

porphyry 0/2

Round sand

Density(g/cm³)

2.61

2.72

2.71

2.71

2.72

2.62

Volume (%)

7.7

19.9

22.4

16.6

25.1

8.4

Mass (%)

7.4

20.0

22.5

16.7

25.3

8.1

Table 5: Composition of the reference mix AC 0/10 (dry aggregates)

Figure 9: Grading of the reference mix AC 0/10, compared to the specifications ofSB250 (Flemish standard tender specifications)

binder and for the wax modified binders. All wax modifica-

tions in the asphalt mix tests are made with wax-E.

Compaction tests

The gyratory compactor was used according to the

European standard (EN 12697-31). The mix preparation

procedure followed EN 12697-35. According to this

standard, the reference temperature (temperature at

which compaction starts) of the hot mix asphalt type AC

0/10 should be 150 °C (for a bitumen B 50/70). When the

compaction temperature is decreased, the viscosity of

the binder increases and it becomes more difficult to

compact the mix. This is seen in figure 10, where the void

content increases with deceasing compaction

temperature, although the sensitivity of the void content

to compaction temperature is not very high. Each result

presented in figure 10 is the average of three compaction

tests. The temperatures on the horizontal axis are

compaction temperatures. The mixing temperature was

systematically 20 °C above the compaction temperature.

Compaction was started when the temperature in the mix

was at the compaction temperature ±5 °C. Figure 10 also

shows the effect of using a wax-modified binder (a pen

80+3% wax-E) and a softer base binder (B180, without

wax). The temperature reduction based on equi-viscosity

levels would for these two samples be about 10°C for the

waxy sample, and 18°C for the B180.

Figure 10 shows that, at 150°C and at 135 °C, the wax-

modified binder gives a somewhat lower void content

compared to the reference mix. At 120°C, 105°C and at

90°C the void content is almost the same. Although the

effects are small compared to the standard deviations

(error bars), the averages over the two highest

temperatures indicate that the same void content as the

hot mix can be obtained for mixes with wax and with a

temperature reduction of about 10°C. These tests also

Figure 10: Void content at 200 gyrations as function of compaction temperature(mixing temperature always 20°C above compaction temperature).

Research Paving Temperatures

www.masterbuilder.co.in • The Masterbuilder - February 2012 75

show that a temperature reduction of 30 °C, as is

advertised by wax producers will result in a larger void

content of the wax modified mixes compared to the

reference mix prepared at the reference temperature of

150°C. For the very soft and unmodified binder, B180, the

compaction was only tested at one temperature, 120°C

and at this temperature clearly a larger temperature

reduction would be possible, but of course this result is

only based on the three repeats at one temperature and

this mix would perform worse for rutting compared to the

reference mix.

In addition, the MLPC plate compactor was used for the

preparation of test plates (dimension 50x18x5 cm) to be

used for the wheel tracking tests described in the following

paragraph. The plates prepared with the wax-modified

binder, when compacted at 135 °C, had a smaller void

content than the plates prepared with the reference

binder, when compacted at 150 °C. The improved

compactability with the wax-modified binder is thus also

seen in the plate compactor, but since the number of

compacted plates is very limited, it is not possible to

derive quantitative information regarding the amount of

temperature reduction from the plate compaction tests.

Wheeltracking tests

A few rutting tests were performed in order to verify the

assumptions made in section 2.5. The tests were

performed with the MLPC rut tester at 50°C. The selected

binder and binder-wax blends were:

Reference binder

B180+5% wax, B120+5% wax, B80+3% wax

With the reference binder, three sets of plates were

prepared and tested: one set was compacted at 150 °C,

one at 120°C, and the one at 90 °C.

From the limited number of rutting tests that were

performed, graphically shown in figure 11, we can already

Figure 11: Wheel tracking tests on reference and some selected wax modifiedbinders, at 50°C.

draw some preliminary conclusions:

- The experimentally determined rut depths of the

samples modified with waxes, using the MLPC rut

tester at 50°C, cannot be predicted by the LVE stiffness

level and also not by the stiffness level (50°C, 0.01Hz)

at 300% strain. The rut depths are much larger as

would be predicted from these two stiffness levels.

- For these (few) rutting experiments, no relation

between binder stiffness versus rut depth could be

obtained, if the stiffness obtained at a fixed strain level

was used, instead by using the stiffness obtained at

fixed stress levels it was possible to have an agreement

between the rut depths, obtained until now, and the

binder stiffness. A stress level of 2000Pa (50°C and

0.01Hz) is at this stage still in agreement with the test

results obtained in this project and also in ref 7. This

stress was obtained by comparing rut depths found

for the wax-modified mixes to rut depths of unmodified

mixes, in the same mix design. For example the sample

B180+5% wax-E has similar rut depths as a mix

prepared with an unmodified B70/100 mix, and the

sample B80+3% wax-E has a rut resistance similar to

the reference mix. The stress level found here will

certainly depend on the particular mix design used

(binder film thickness, void content, angularity of

aggregate material,…) and also on the particular type

of rutting equipment used (load levels, rate, …), but

this was not investigated in this study. For a number of

other binders (unmodified and polymer modified) the

stiffness level at a stress level of 2000Pa (and at 50°C

and 0.01Hz) is still inside or just on the starting point

of non-linearity. This would still be in agreement with

the findings from our previous study (ref. 7), where rut

depths could be predicted using LVE stiffness levels,

since this study was only using unmodified and

polymer modified binders, for which the stress level is

not a crucial parameter (see also figure 5).

In figure 12 the stiffness levels at 2000Pa of unmodified

and several WMBs binders are shown. Figure 12 indicates

that for 3% wax added, the softest base binder that can

be used without deteriorating the rutting resistance would

be a pen 80 binder. For 4% wax addition, this would be a

pen 90 and for 5% wax a pen 110.

Discussion and Conclusions

In this paper, general properties of commercial waxes

and of wax modified binders (WMBs) were shown. Most

waxes (as received) show rather large peaks in the DSC

signals, associated with crystallizing and melting material.

The crystallization and melting temperatures can vary a

lot as well as the degree of crystallinity. In some cases the

crystallization and melting temperature ranges are very

Research Paving Temperatures

The Masterbuilder - February 2012 • www.masterbuilder.co.in76

broad, covering a temperature range from 20°C to above

100°C. Waxes show some interaction with bitumen since

upon adding wax to bitumen the melting point depression

can be considerable, 20 to 40°C. For those waxes with

only a small degree of crystallinity in the pure form, no

signals of crystallinity in the blended form were observed,

most likely these waxes dissolve completely in the

bitumen. These waxes soften the base binder at all

temperatures and are not suited as an additive in asphalt.

Most waxes have in the liquid form a viscosity that is below

the viscosity of bitumen and therefore they can indeed be

used as viscosity reducers. However upon addition of 3%

of wax to a reference binder the reduction in viscosity,

expressed as a shift in temperature, is limited to 6°C in

the best case. Larger effects on the viscosity reduction, in

the range of 15 to 20°C, can be achieved by increasing

the amount of wax added (which is economically not

always feasible) or by increasing the penetration level of

the base binder. The viscosity reduction as a function of

three wax contents (3%, 4% and 5%) and as a function of

penetration level of the base binder has been evaluated

in detail. But if the penetration level of the base binder is

reduced the wax should stiffen this base binder sufficiently

at high service temperatures where rutting can take place

and should at these temperatures be in the crystalline

form. Waxes with enough crystalline material, melting at

high enough temperatures, have a large effect on the R&B

temperature, on the SHRP PG temperature for rutting,

and also on the complex modulus at 50°C. These binder

tests suggest that these waxes will improve the rutting

resistance. However, it was also observed that WMBs are

rather strain sensitive, so the stiffness quickly decreases

if strain or stress is increased. Since, at this moment it is

not clear what strain levels the binder feels when loaded

in a mix, it is also not clear how waxes influence the rutting

resistance.

Asphalt mix tests were conducted to verify on one hand if

the viscosity changes are directly related to changes in

compactibility and on the other hand to verify how the

increased stiffness after adding wax to bitumen influences

the rutting susceptibil ity. It has been shown that

compactability levels measured using the gyratory

compactor and the plate compactor are in agreement

with the values derived from equi-viscosity levels of the

bitumen-wax blend. A limited number of rut tests have

been conducted; these tests show that the linear visco-

elastic (LVE) stiffness levels of wax-modified binders over-

estimate the rutting performance. For the conditions used

in this study (for the particular mix design and rutting

equipment used) rut depths can be related to the stiffness

at a given high stress level at the same temperature as

the rutting test and at a low frequency of 0.01Hz. For the

WMBs this stress level is clearly outside the LVE range,

while for unmodified and polymer modified binders it is

inside or almost inside the LVE range.

The conclusions from this paper are listed below:

- Commercial waxes proposed for mixing into bitumen

vary with respect to melting temperature and melting

enthalpy.

- The most effective wax for temperature reduction of

bitumen is a wax with a low viscosity at the temperature

of interest, and in relation to performance with a

distinct melting peak at high enough temperatures

and a high melting enthalpy. The maximum

temperature reduction with 3% of wax is about 6°C

(based on binder viscosity and compared to the same

base binder).

- The increased stiffness of the wax modified bitumen

at temperatures where the wax is solid can be used

for selection of a softer bitumen to further decrease

the viscosity at construction temperatures.

- Unmodified bitumen is much more strain and stress

resistant than wax-modified bitumen. Thus the

increased stiffness cannot fully compensate for the

use of a softer binder.

- The range of temperature reduction obtained from

compaction tests are in agreement with the predicted

range of temperature based on equi-viscosity levels.

- The rutting resistance of wax-modified mixes (in

laboratory tests) cannot be predicted by the LVE

stiffness level. The LVE stiffness over-estimates the

behavior of wax-modified mixes.

Acknowledgements

The funding of IWT (Instituut voor de Aanmoediging van

Innovatie door Wetenschap en Technologie in

Vlaanderen) is gratefully acknowledged. The authors also

Figure 12: Stiffness at 50°C and 0.01Hz at a stress level of 2000Pa versuspenetration of the base binder.

Research Paving Temperatures

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The Masterbuilder - February 2012 • www.masterbuilder.co.in78

acknowledge the input of the Nynas Technology

Department Antwerp, and of the laboratory of BRRC.as

well as the Nynas laboratory in Nynäshamn for DSC testing.

References

1 G.C. Hurley, B. D. Prowell, "Evaluation of Sasobit for use in

warm mix asphalt", NCAT report 05-06, June 2005

2 G.C. Hurley, B. D. Prowell, "Evaluation of Potential Processes

for Warm Mix Asphalt", AAPT, 2006, P.41

3 K-W. Damm, "Die untersuchungsstrecken temperaturabgesenkte

asphalte auf der BAB A 7 und B 106" Strasse + Autobahn,

2.2006, P.65

4 L. Keller, H. Pätzold, "Nachweis der W irksamkeit von

temperaturerniedrigenden Zusätzen in Walzaphalten", 2.2006,

P.83

5 L. Drüschner, "Low temperature asphalt - Experience in rolled

asphalt" 3rd E&E Congress Vienna 2004, paper Nr.198, P. 1019

6 K. W. Damm, "Asphalt flow improvers - a new technology for

reducing mixing temperature of asphalt concrete mixes with

high restistance against permanent deformation", Sixth

International RILEM Symposium on Performance Testing and

Evaluation of Bituminous Materials 2003 P.520

7 H. Soenen, J. J. De Visscher, T. Tanghe, A. Vanelstraete, P.

Redelius, " Selection of Binder Performance Indicators for Asphalt

rutting based on Triaxial and Wheel tracking tests" AAPT,

2006, P.165

8 H. Soenen, J. De Visscher, A. Vanelstraete, P. Redelius,

"Influence of Thermal History on Binder Rutting Indicators", Int.

J. Road Mat. Pavement Design, Vol. 6, p. 217, 2005.

9 J. D'Angelo, R. Dongre, "Development of A High temperature

Performance Based Binder Specification it the United States",

10th Intern. Conf. on Asphalt Pavements, Québec 2006

10 F. Long, C. L. Monismith "Laboratory testing to develop a non-

linear viscoelastic model for rutting of asphalt concrete" Sixth

International RILEM Symposium on Performance Testing and

Evaluation of Bituminous Materials, 2003, P. 506.

11 S. Kose, M. Guler, H. Bahia, E. Masad, "Distribution of Strains

within Hot Mix Asphalt Binders", applying imaging and finite-

element Techniques" TRR, 1728 p. 21-27 (2001)

12 D. Witheoak, The Shell Bitumen Handbook, Chapter 13, Shell

Bitumen UK, ISBN-0-9516625-0-3, 1991

13 H. U. Bahia, D. I. Hanson, M. Zeng, H. Zhai, M. A. Khatri, R. M.

Anderson, "Characterization of Modified Asphalt Binders in

Superpave mix design", Transportation Research board, National

Research Council, NATIONAL ACADEMY PRESS

WASHINGTON, D.C., 2001

14 J. De Visscher , F. Vervaecke, A. Vanelstraete, H. Soenen, , T.

Tanghe, P. Redelius, "Asphalt production at reduced temperatures

and the impact on asphalt performance" submitted to the Intern.

Conf. on Asphalt Pavements, Zürich 2008.

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Roller Compactor Cum Rut Analyzer(RCRA) an Alternative Compactorfor Bituminous Mix Design

1Dr. B.V. Kiran Kumar, 2Dr. H.S. Jagadeesh,3Dr. R. Sathyamurthy³1Assistant Professor in Civil Engineering, Govt. SKSJTI, Bangalore2Professor, Department of Civil Engineering, BMSCE, Bangalore3Visiting Professor, Department of Civil Engineering, BMSCE, Bangalore

Compaction plays a vital role in performance of a bituminous mixes. In India Marshall Method is adopted for designing bituminousmixes where specimens are prepared using Marshall Hammer. Compaction effort generated by Marshall Hammer doesn't simulatethe field compaction effect which leads aggregate degradation during mix design. Other draw back of Marshall Procedure is thenumber of blows given to compact the specimen is fixed and during compaction the densification data of mixes cannot berecorded, this data plays a vital role in determining Theoretical Maximum Density (TMD). Recent advancement in bituminous mixcompaction is Superpave Gyratory Compactor (SGC) a product of Strategic Highway Research Program (SHRP), which simulatesthe field compaction effect during specimen preparation for mix design at laboratory. Further it also records the densification dataduring compaction of mix. With these methods available to compact the bituminous mix at laboratory during mix design, anothercompacting equipment known as Rolling Compactor cum Rut Analyzer (RCRA) (Patent Pending) machine which is indigenouslydeveloped by the authors was used in this project, where it compacts the specimen in laboratory by generating field compactioneffect of a roller as well as records densification data of the mix during compaction. Later the same is used to evaluate theperformance of mix in terms of rut potential. In this project an attempt was made to evaluate the performance of bituminous mixesdesigned using three types of compaction equipments, based on the results obtained suitability of the compaction equipmentsto be adopted during bituminous mix design at laboratory has been suggested.

It is well known fact that the quality of bituminous pavement to a

greater extent depends upon the degree of compaction.

Depending upon the degree of compaction, the strength,

durability and stability of the bituminous pavement vary with

variation in compaction. The objective and sufficiently accurate

control on the degree of compaction appears to be the most

important factors. In India procedure followed at laboratories

during compaction of specimen for mix design does not

represent the field conditions this leads to ambiguity in the results

obtained by testing such sample. In laboratory the specimens

prepared by Marshall Method of compaction do not match the

field compaction condition. In Marshall method of mix design,

the specimen is compacted by confining the mix in all direction

using a metallic cylindrical mould, where the mix is compacted

by using an hammer which has specific weight and height of fall.

A total of 150 blows are given to compact the specimen. Further

the compaction method leads to degradation of mineral

aggregate, as the aggregates are confined in all direction and

has no scope to realign and reorient during the compaction of

mix by dropping hammer. Whereas in field aggregates which

come under the roller will be subjected to kneading action and

will be compacted with less chance of aggregate degradation

since they have the scope to realign and reorient them self.

Hence aggregate degradation during laboratory mix design

leads to increase in optimum binder content of the mix and

optimum binder content thus obtained when transferred to the

field leads to functional and structural failure of pavements.

Bituminous Mix Design Practice in India

In India, highway agencies still adopt Marshall method of

bituminous mix design. The Marshall method entails a laboratory

experiment aimed at developing a suitable bituminous mixture

using stability / flow and density / voids analysis. The advantage

of Marshall method is its attention to density and voids properties

of bituminous mixes. This analysis ensures the volumetric

proportions of mix materials for achieving a durable mix which is

Compaction Laboratory Study

www.masterbuilder.co.in • The Masterbuilder - February 2012 109

backed by field performance data (Kiran Kumar et. al, 2005).

The Marshall specimen used to determine the volumetric

properties of a bituminous mix is prepared using a Marshall

Hammer which is used to compact the specimen under a

confinement by giving 50 or 75 blows on both sides of specimen.

The number of blows given to compact specimen depends on

traffic. The weight of hammer used to compact is 44.52 N and

height of fall being 457 mm. During this process the aggregate

degradation takes place, aggregate structure which is carefully

chosen to achieve maximum density is lost. Where in case of

field compaction of bituminous mix under a roller, the material

has certain scope for the movement or adjust itself under the

roller with this, in field compaction the bituminous mixes are

subjected to kneading action but in case of a Marshall hammer

the blow given by hammer from a height of 457 mm damages

the aggregate structure by producing dynamic loading effect

rather then kneading action. Recent advancement in Marshall

method of compaction is to use indented Marshall hammer, by

doing so the compaction of specimen will be similar to the field

compaction this is because the indent caused on face of Marshall

hammer allows the aggregate to realign when it is compacted

using Indented Marshall hammer.

Introduction to Superpave Gyratory Compactor (SGC)

Strategic Highway Research Programme (SHRP) developed a

compactor known as Superpave Gyratory Compactor (SGC)

which simulates field compaction effect at laboratory. The SGC

is used to produce specimens for volumetric analysis during a

bituminous mix design and it also records data to provide a

measure of specimen density throughout the compaction. The

unique features of SGC are a loading mechanism which presses

against the reaction frame and applies a load to the loading ram

to produce a 0.6 n/mm2 compaction pressure on the specimen.

The SGC mould has a base plate at bottom and the mould which

provides confinement during compaction. The SGC base rotates

at a constant 30 revolutions per minute during compaction with

the mould positioned at a compaction angle of 1.25o (SP-2,

2001). Specimen height measurement during compaction is an

important function of SGC. Specimen density can be estimated

during compaction by knowing the mass of material places in

the mould, the inside diameter of the mould and the specimen

height. Using these measurements the specimen's compaction

charac-teristics can be developed. Here since the base is rotated

at an angle of 1.250 this accommodates the movement of the

material without getting confined in mould and this also helps in

reducing aggregate degradation. The constant pressure applied

from the top and rotation of base compact's the mix by kneading

action which is similar to that of field compaction of bituminous

mix under a roller.

Introduction to Rolling Compactor and Rut Analyzer(RCRA)

The RCRA is an indigenously developed compactor by the

authors. The unique features of this compactor are it can apply a

constant pressure of 0.6 n/mm2 and if required the pressure

can be applied up to 3 n/mm2. Similarly the rolling speed in the

compactor can be varied. It has a temperature control unit which

maintains the pre selected compaction and rut test temperature.

The equipment can record densification data of the mix while

compaction. Using the densification data the specimen's

compaction characteristics can be developed. The compactor

is an hydraulically operated with twin non return valve system

and has a Programmable Logical Circuit (PLC) which is inturn

connected to vertical and horizontal transducers capable of

recording changes of + 5 mm.

The following are the novel features of RCRA.

- RCRA produces field compaction effect (kneading effect) in

laboratory during compaction of specimens in bituminous

mix design.

- RCRA can record the densification data during compaction

of specimen.

- RCRA can maintain a Pre selected temperature during

compaction or rutting test.

- RCRA is a completely stable Machine and does not require

foundation to install.

- RCRA is mounted on castor wheels and can be transported

with easy and can be used as quality control machine at site

or laboratory.

- RCRA can be operated with ease and it is maintenance free.

- RCRA has a capability of applying pressure up to 3 n/mm2

so that tyre and compaction pressure can be varied and its

effect on mix can be studied.

- RCRA is capable of change in speed during rolling or rutting

operations.

- The entire operation of compaction of slab and rutting test is

automated and there is less human intervention to temper

the test results.

Formulation of Problem

The issue addressed earlier regarding the compaction by

Marshall Hammer doesn't simulate the field condition during

compaction in laboratory and hence it is to be replaced by a

compactor which can replicate or simulate field compaction

during preparation of the sample in the laboratory. In order to

cater for these requirements a design practice was developed

by the United States Congress named has SHRP one of the

main objectives of this programme was to develop a compactor

which can simulate the field condition during preparation of

specimen for mix design. But SGC developed under the SHRP

was able to simulate the field compaction effect during laboratory

specimen preparation to some extent. But the problems faced

Compaction Laboratory Study

The Masterbuilder - February 2012 • www.masterbuilder.co.in110

in this compactor were, it is an expensive compactor and very

sophisticated equipment which needed a lot of maintenance.

Another issue with SGC was that, it cannot prepare a specimen

in the desired shape and size. For example SGC cannot prepare

a Beam Specimen or a Slab Specimen which are required for

various performance tests in order to evaluate the bituminous

mix. These difficulties have led the researchers to find an

alternative compactor which can simulate the field compaction

and also be cost effective and versatile. In present study an

ernest effort is made to over come the above difficulties by

using RCRA. Where RCRA generates the field compaction effect

(i.e., kneading action) with that it can produce different shapes

and size of specimens for various performance tests on

bituminous mix. In current study mix design was conducted on

Bituminous Concrete (BC) Grade-2 using three different

compaction equipments viz., Marshall Hammer, Superpave

Gyratory Compactor and Rolling Compactor cum Rut Analyzer.

Optimum Binder Content (OBC) of the mix for three compactors

was found out. Further BC Grade-2 specimens were cast using

different compactors at there respective OBC's, these

specimens were subjected to performance tests such as Fatigue

Test, Indirect Tensile Strength test, Rutting, Binder Recovery and

Moisture Sensitivity test. Suitability of compactors for mix design

at laboratory was evaluated using the above performance test

results.

Laboratory Studies

Material Characterization

Test on Bituminous Binder

Bitumen of Viscosity Grade-30 (VG-30) grade was used for the

present studies, tests on binder, results and codes of practice

followed are indicated in Table 1.0.

Tests on Aggregates

The physical requirements and test values obtained for the coarse

aggregates to be used in BC Grade-2 pavement layer as per

Ministry of Road Transport and Highway (MoRT&H) fourth

revision specifications are indicated in Table 2.0.

Grading of Commercial Available Mineral Aggregate

The mineral aggregate is graded by performing sieve analysis.

Sieve analysis of each aggregate fraction was done separately

as well as for the aggregate blend, once the proportioning was

finalized. Gradation sample is indicated in Table 3.0. Table 4.0

shows MoRT&H specifications for BC Grade-2.

Proportioning of the Mineral Aggregate Blend

Aggregate must be blend in such proportion that, the final blend

should be in the acceptable range as given in table 4.0. Table 5.0

and Figure 1.0 shows proportioning mineral aggregate used for

present study.

Test Description & Code

Penetration at 25ºC, 100 g, 5 s,0.1 mm. (BIS 1203-1978

reaffirmed 2008)

Softening Point (R&B), ºC, Min(BIS 1205-1978 reaffirmed 2009)

Viscosity at 135 0C in CPS(ASTM 4402-2006)

Specific Gravity (BIS 1202-1978reaffirmed 2008)

Flash Point (º C) (BIS 1209-1978reaffirmed 2009)

Solubility in Trichloroethylenepercent, Min. (BIS 1216-1978

reaffirmed 2009)

Viscosity Ratio on residue of ThinFilm Oven Test (TFOT) Sample

600C, Max (BIS 1206(Part-2)-1978& 9382-1979 both reaffirmed 2009)

Ductility at 250C, cm, Min, onresidue of TFOT Sample (BIS 1208

1978 & 9382-1979 both

reaffirmed 2009)

Results

65

48.6

398

0.997

276

99.0

2.8

54

Requirment of VG-30

as Per BIS 73-2006

50-70

47

350

0.9 – 1.02

220

99.0

4.0

40

Table 1.0 Test Results for VG-30 Bitumen

Design Binder Content

After finalizing the aggregate structure, specimens for three

different compactors were prepared at varying binder contents.

Sl.No

1

2

3

4

5

6

Test

Description

Combined F&EIndex (%)

Specific Gravity

Water Absorption(%)

Impact Value (%)

L.A. AbrasionValue (%)

Soundness with

MgSo4

Test Method

IS:2386(Pt I-1963)

IS: 2386(Pt IV- 1963)

IS: 2386(Pt III- 1963)

IS: 2386(Pt IV- 1963)

IS: 2386(Pt IV- 1963)

IS: 2386

(Pt V- 1963)

Result

20 mm

23.5

2.658

0.25

15.30

16.8

6.25

10 mm

21.5

2.647

0.40

Stone Dust

-

2.538

-

-

-

-

Table 2.0 Test Results of Aggregates

A minimum of four binder contents were tried and at each binder

content minimum of three specimens were prepared. Mix

properties were evaluated for the selected blend at the different

binder contents, by using the densification data. The volumetric

properties were calculated at different binder content. From the

above data, graphs such as air voids, VMA and VFA versus

binder content were plotted. The design binder content was

Compaction Laboratory Study

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The Masterbuilder - February 2012 • www.masterbuilder.co.in112

Table 3.0 Grading of Commercially Available Aggregates

GRADING

IS Sieve (mm)

26.5

19

13.2

9.5

4.75

2.36

1.18

600µ

300µ

150µ

75µ

Cumulative % by Weight of Total Passing

-

100

79-100

70-88

53-71

42-58

34-48

26-38

18-28

12-20

04-10

2

Nominal Aggregate

Size

Layer Thickness

13mm

30-45mm

Sieve

Size

19 mm

13.2 mm

9.5 mm

4.75 mm

2.36 mm

1.18 mm

600µ

300µ

150µ

75µ

% Passing

Coarse (20mm)

90

29

1

-

-

-

-

-

-

-

Fine (10mm)

100

100

66

11

1

-

-

-

-

-

Stone dust

100

100

100

96

76

51

29

17

9

5

Lime

100

100

100

100

100

100

100

100

100

85

Table 4.0 MoRT&H Specifications

established at 4% air voids and all other mixture properties such

as VMA and VFB were checked at the design binder content to

verify that they meet the criteria.

Sieve

Size

(mm)

19

13.2

9.5

4.75

2.36

1.18

600

300

150

0.75

Proportioning of Mineral Aggregate Blend

20

mm

35

10

mm

20

Stone

dust

40

Lime

5

Combined

Gradation

97

75

59

46

36

25

17

12

9

6

MoRT&H

Specifications

% BlendingLower

Limit

100

79

70

53

42

34

26

18

12

4

Upper

Limit

100

100

88

71

58

48

38

28

20

10

32

10

0

0

0

0

0

0

0

0

20

20

13

2

0

0

0

0

0

0

40

40

40

38

30

20

12

7

4

2

5

5

5

5

5

5

5

5

5

4.25

Table 4.0 MoTable 5.0 Proportioning of the Mineral Aggregate BlendRT&H

Specifications

Figure1.0 Shows Proportioning of Materials

Bituminous Mix Design

Mix Design using Marshall Hammer and SGC

OBC of selected aggregate blend and VG-30 binder for Marshall

Hammer and SGC were obtained as per ASTM 6926, 6927-2006

and SP-2-2001 standards respectively.

Mix Design using RCRA

Slabs of 63.5 mm height 270 mm wide and 600 mm in length at

varying binder content were prepared using RCRA. Cores of

100 mm diameter were drawn from the slabs, OBC and other

volumetric properties were found out using cores drawn. Figure

2.0 explains step by step process involved in bituminous mix

design using RCRA. Step-1 involves, mixing aggregate blend

with varying binder content by weight of mix then heat the same

and further place in RCRA for compacting into slab. Step-2

involves drawing cores from compacted slabs in order to

determine the density voids characteristics of the mix. Step-3

determines the voids and density properties of the cores drawn.

Based on the voids and density relation OBC for the mix is

established. Step-4 involves determination of Marshall Stability

of the mix. This was done in order to ensure that the mix

compacted using RCRA satisfies the Marshall Stability and Flow

value criteria.

Results of BC Grade-2 Mix for three Compactors

The compaction of the aggregate structure chosen for BC Grade-

2 confirming to MoRT&H limits was done using three compactors

and table 6.0 and figure 3.0, 4.0, and 5.0 indicate BC Grade-2 mix

properties for the compactors.

Evaluation of Moisture Sensitivity

Specimens for BC Grade-2 were cast at their design binder

contents obtained for compactors and tested as per AASTHO T-

283 moisture evaluation test, one subset of three specimens

Compaction Laboratory Study

www.masterbuilder.co.in • The Masterbuilder - February 2012 113

were compacted to approximately 7 percent air voids at design

binder content and named as controlled specimens. One more

subset of three specimens was cast with design binder content

at 4 percent air void content. The evaluation for moisture sensitivity

was done by thawing cycle only. The controlled subsets of three

specimens are conditioned by subjecting the specimens to

partial vacuum saturation that is, the specimens were kept at

Step: 1 Placing and Compaction of Mix

Step: 2 Drawing Cores from Compacted Slabs

Step: 3 Measuring Height and Bulk Density of Core Specimen for Volumetric

Analysis

60oC for 24 hours in water bath followed by 2 hours in temperature

controlled chamber at 25oC. The other subset of three specimens

was kept in a temperature controlled chamber at 250C for 2

hours and these specimens were called as unconditioned

Sl.No.

1

2

3

4

5

6

7

8

Properties

OBC in (%) byWeight of mix

Stability in (Kg)

Retained Stabilityin (Kg)

Flow in (mm)

Bulk Density in(gm/cc)

Volume of AirVoids in (%)

Volume in MineralAggregate in (%)

Volume filled by

Bitumen in (%)

Marshall

Hammer

Compaction

5.10

1710

1395

3.0

2.364

4.0

15.90

75.10

SGC

Compaction

4.80

2391

2238

3.5

2.410

4.0

15.25

73.70

RCRA

Compaction

4.90

1950

1750

3.5

2.390

4.0

14.38

72.18

Table 6.0 Properties of BC Grade-2 Mix for three Compactors

Step: 4 Measuring Marshall Stability and Flow Value

Figure 2.0 Steps Involved in Mix Design by RCRA

Figure 3.0 Optimum Binder Content for Three Compactor

Figure 4.0 Voids in Mineral Aggregate for Three Compactors

Compaction Laboratory Study

The Masterbuilder - February 2012 • www.masterbuilder.co.in114

specimens. All the specimens were tested for their indirect tensile

strengths and the ratio of conditioned to that of unconditioned

specimens indirect tensile strength was represented as Tensile

Strength Ratio (TSR). Figure 7.0 indicate a typical comparison of

TSR values obtained for BC specimens compacted at OBC's

for three compactors viz., SGC, RCRA and Marshall Hammer

using VG 30 grade binder. Table 7.0 indicates Indirect Tensile

Strength values of BC Grade-2 mix for three compactors and

VG 30 grade binder.

IDT*- Indirect Tensile Strength of Conditioned Sample in kg/cm2

IDT**- Indirect Tensile Strength of Unconditioned Sample in kg/

cm2

SGC - Super Gyratory Compactor

RCRA - Rolling Compactor cum Rut Analyzer MH - Marshall

Hammer

Figure 5.0 Voids Filled with Binder for Three Compactors

Figure 6.0 Densities for Three Compactors

where,

TSR = Tensile Strength Ratio (percent)

For example Average tensile strength of conditioned sample =

19.07 kg/cm2 and Average tensile strength of controlled samples

= 19.63 kg/cm2 then

Compactors

SGC

RCRA

MH

VG 30 Grade

IDT *

19.07

18.80

17.87

IDT **

19.63

19.00

18.32

TSR

97.14

98.94

97.54

Table 7.0 Indirect Tensile Strength Value of BC Grade-2 Mix for three Compactors

The tensile strength ratio comes out to be 97.14 % where the

value is higher than the criteria specified by MoRT&H for BC

mixes. The criteria being 75% all the specimens compacted by

various compactors at there OBC's qualified the test.

Rutting Test

Rutting test was conducted on the specimens cast at OBC's of

different compactors and were conditioned at 60+10 C. A tyre

Figure 7.0 Comparison of Indirect Tensile Strength Value of BC Grade-2 for Three

Compactors

pressure of 6.2 kg/cm2 was maintained constantly through out

the test. It was observed that the specimen cast at OBC's of

RCRA and SGC showed same deformation trend in the graph

up to 1500 passes later RCRA sample showed some significant

improvement in deformations up to 2000 passes then SGC and

Marshall Hammer specimens, but later failure was rapid. Here

specimen cast using OBC obtained from Marshall Hammer failed

at 1100 passes. Figure 8.0 and 9.0 indicate comparison of

rutting test results at 60 + 10 C for BC Grade-2 with VG 30 binder

and Rutting test in progress respectively

Compaction Laboratory Study

RAnand

Text Box

STP Ltd

The Masterbuilder - February 2012 • www.masterbuilder.co.in116

Fatigue Test

Specimens were prepared using different compactors viz.,

Marshall, SGC and RCRA at their respective OBC's and was

subjected to repeated loading at rate of 60 cycles/min, at stress

levels of 40% and 50% of Indirect Tensile Strength value obtained

for each compactor earlier. It was observed that both SGC and

RCRA specimens were able to carry load 1.5 times more that of

Marshall Hammer specimen. Figure 10.0 shows the fatigue test

results at 60 +10 C for BC.

Binder Extraction Test

Binder extraction test was conducted in order to evaluate the

aggregate degradation that would take place due to variation in

the type of compaction while preparing the specimen. The tables

8.0 indicate that the RCRA compacted specimens results in a

maximum of 3% aggregate degradation whereas SGC

compacted specimen shows a maximum variation of 5% and

Marshall Hammer compacted specimen show a maximum

variation of 10%. The test was a clear indicator that RCRA

compacted specimens where subjected to less aggregate

Figure 8.0 Comparison of Rutting Test results at 60 + 10 C

Figure 9.0 Rutting Test on Bituminous Slab using RCRA

degradation this can be attributed to the kneading effect of

compactor and creation of enough space in the mould (270 X

650 mm) which provide enough scope for the aggregates to

adjust and realign themselves when it is subjected to compaction.

Conclusion

It was found that the OBC for BC mix at 4.0 % air voids design

criteria where 5.1, 4.8 and 4.9 percent by weight of mix, when

compacted using Marshall, Superpave and Rolling Compactor

respectively. Here the lower binder content for the same

Figure 10.0 Comparison of Fatigue Test at 60 + 10 C

aggregate structure was obtained by using SGC and maximum

stability of 2391kgs is shown by the specimen compacted using

SGC wherein the aggregate and binder being the same for all the

three compactors. In case of a Roller Compactor specimens

exhibited stability value which was near to that of SGC this is

because in case of RCRA and SGC the specimen is compacted

to obtain the maximum theoretical density but in case of Marshall

the number of blows are confined to 75 or 50 on each side of

mould based on the traffic conditions. The density of SGC

compacted specimens were higher when compared to specimen

compacted using other compactors and this has been

substantially supported by the test results of moisture sensitivity

test wherein the specimens compacted by SGC has more

resistance to moisture damage than that of specimens

compacted by other compactors. There is an improvement in

the compaction characteristics of specimens compacted using

SGC and RCRA compactors when compared to Marshall

Hammer. In case of Rutting test specimens cast at OBC of RCRA

Sieve Size in mm

19

13.2

9.5

4.75

2.36

1.18

0.6

0.3

0.15

0.075

Gradation After Binder Extraction Test

MH

89

67

47

58

45

31

37

18

14

10

RCRA

97

73

57

44

34

27

19

15

10

6

Desired Gradation

97

75

59

46

36

25

17

12

9

6

SGC

93

74

55

45

32

25

21

15

11

8

Table 8.0 Gradation after Binder Extraction Test

Compaction Laboratory Study

www.masterbuilder.co.in • The Masterbuilder - February 2012 117

performed much better than of specimens cast at OBC's of

SGC and Marshall. RCRA specimens carried 2500 passes before

causing a rut of 20mm, whereas SGC specimen sustained 2200

passes by causing 20mm rut. Whereas Marshall specimen

sustained 1600 passes only. In case of fatigue test SGC and

RCRA specimens carried 1.5 times more repetitions then that of

Marshall hammer compacted specimen. Further binder

extraction test has clearly exhibited that specimen compacted

by using RCRA undergoes less aggregate degradation since

the compaction provides enough scope for the aggregates to

realign and adjust during compaction of specimen when

compared to SGC or Marshall Hammer compacted specimen,

where the aggregate structure and binder remain same for all

the compactors. From the above study it can be concluded that

RCRA is a compactor which produces compaction effect which

is similar to field compaction and aggregate degradation does

not happen. It can be used as quality control equipment and

determine the rutting characteristics of various bituminous

binders. Further it is required to take up a full fledge study by

laying test tracks of BC layer with various OBC's obtained from

these compactors and the test tracks needs to be evaluated at

a constant interval.

Acknowledgement

The work reported herein was conducted as a research studies

at Dayananda Sagar College of Engineering, Bangalore and B.M

Srinivas College of Engineering, Bangalore. The authors

acknowledge the efforts of several research assistants and

graduate students who were involved in the research program.

The research programme was sponsored by All India Council of

Technical Education (AICTE), New Delhi and M/s. Tinna Overseas

Limited, New Delhi.

Disclaimer

The contents of this paper reflect the view of the authors who are

responsible for the facts, findings and data presented herein.

Reference

- Anderson R.M., Turner A. P., Peterson L. R., and Mallick B. R.,

"Relationship of Superpave Gyratory Compaction Properties to

HMA Rutting Behavior", Transportation Research Board, NCHRP

Report 478, Washington D.C, 2002, pp 1-16.

- Joe W. Button, D.N. Little, V. Jagadam & O.J. Pendelton,

"Correlation of Selected Laboratory Compaction Methods with

Field Compaction", Transportation Research Record 1454, TRB,

National Research Council, Washington, D.C., July 1994, pp

193 - 201

- Ministry of Roads Transport and Highways (MoRT&H),

"Specifications for Road and Bridge Works", Fourth Revision,

Indian Roads Congress (IRC), 2001

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Wheel Tester To Evaluate Rutting of Asphalt Samples Prepared

by Superpave Gyratory Compactor", Transportation Research

Record 1545, TRB, National Research Council, Washington,

D.C., Nov. 1996, pp. 161-168.

- Rajib B. Mallick, "Use of Superpave Gyratory Compactor to

Characterize HMA", Transportation Research Record 1681,TRB,

National Research Council, Washington, D.C., 1999, pp. 86 -

96.

- Mallick, R.B, Buchanan .S and Brown E.R., (1998), "An

Evaluation of Superpave Gyratory Compaction of Hot Mix Asphalt

(HMA)", Transportation Research Record 1638, TRB, National

Research Council, Washington, DC. pp 111-119.

- Hand A.J, Stiady J.L White T.D, Noureldin A.S and Galal. K

(2001), "Gradation Effects on Hot-Mix Asphalt Performance",

Transportation Research Record1767, TRB, National Research

Council, Washington, DC. pp 152-157.

- "Paving Bitumen Specification" (IS: 73), Third Revision, Bureau

of Indian Standards, New Delhi, 2006.

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1220), Indian Standard Institutions, New Delhi, 1978.

- Standard Practice for Preparation of Bituminous Specimens

Using Marshall Apparatus (ASTM D6926- 2006), American

Society for Testing and Materials International, 100 Barr Harbor

Drive, PO Box C700, West Conshohocken, PA, 19428-2959

USA

- "Standard Test Method for Marshall Stability and Flow of

Bituminous Mixtures" (ASTM D6927- 2006), American Society

for Testing and Materials International, 100 Barr Harbor Drive,

PO Box C700, West Conshohocken, PA, 19428-2959 USA

- Punith V.S, Reddy M.P.S and Veeraragavan A, "Characterization

of Bituminous Mixes under Repeated Load Indirect Tensile Tests",

Highway Research Bulletin No. 73, 2005, pp. 131 - 147.

- Sinha V.K, H.N. Singh and Saurav Shekar, "Rutting in flexible

Pavements - A Case Study", Journal of Indian Roads Congress,

Vol 68, No.3, 2007.

- Mc Gennis R.B, Buchanan S and Brown E.R (1998), "An

Evaluation of Superpave Gyratory Compaction of Hot Mix Asphalt

(HMA)", Transportation Research Record1583, TRB, National

Research Council, Washington, DC. Pp 98-105.

- Superpave Level 1 Mix Design, Superpave Series No.2 (SP-1

and SP-2), Asphalt Institute, Lexington, 2003 and 2001.

- B.V. Kiran Kumar, Sridhar Raju, Sunil Bose and K.N. Vishwanath

(2005), "Effect of Air Voids and Compaction Temperature on

Bituminous Mix Design", Advance in Road Transportation National

Conference Proceedings, National Institute of Technology,

Rourkela, Orissa.

- Anderson, R.M., (2002) "Using Superpave Gyratory Compaction

Properties to Estimate the Rutting Potential of Asphalt Mixtures",

Asphalt Paving Technology, Association of Asphalt Paving

Technologists-Proceedings of the Technical Sessions, Vol - 71,

pp 725-738.

Compaction Laboratory Study

The Masterbuilder - February 2012 • www.masterbuilder.co.in118

MFRC Experimental Study

Behavior of Mixed Fiber ReinforcedConcrete (MFRC) Exposed to Acids -An Experimental Study

Urooj Masood1¹, Dr. B.L.P. Swami2², Dr. A.K.Asthana3³

¹Asssociate Professor, Civil Engineering, Deccan College of Engineering and Technology,

Darussalam, Hyderabad, India.

²Professor, Coordinator, Research and Consultancy, Vasavi College of Engineering,

Ibrahimbagh, Hyderabad, India.

³Professor, Principal, Keshav Memorial College of Engineering and Technology,

Narayanguda, Hyderabad, India.

The study presents the findings of the durability criteria of mixed fiber reinforced concrete to acids and salt resistance. Theinvestigation was carried out with different proportions of mixed percentages of alkaline resistant glass fibers and steel fibers intotal fiber content percentages. Comparison of texture, denseness of the exposed and unexposed specimens are done bystudying the properties like pH, conductivity and weight loss at 30 days, 60 days, 90 days, 120 days and 180 days. The pH of theacids and salt is seen to increase and the conductivity values were found to be decreasing for acids and increasing for Na

2SO

4

when compared to fresh solutions. The specimens were tested for compressive strength after 180 days exposure. The specimenswith 75 % glass fibers and 25% steel fibers in all the total percentages of fiber with 1.0 % as optimum showed lesser deteriorationof surface texture. Strength was reduced for all the specimens in different solutions. Brittle failure is reduced with increasing totalpercentages of fibers compared to control specimens. Fiber reinforcement is holding together the crushed specimens. ThusMFRC contributes to better durability as a whole with glass fibers as a major binding reinforcement and steel fibers providing morestrength but lesser when compared to unexposed specimens.

The previous studies on durability of plain and reinforced

concrete structures indicated a satisfactory performance

of the structures during its life period. But when faced

with different environmental exposures the results were

less encouraging with problems of permeability, alkaline

and acidic exposure resulting in corrosion and

deterioration of the structures. This and the last century

has seen a vast progress in the development of new

cementitous materials like silicafume, ground granulated

blast furnace slag being blended with cement or in

concrete that helps in reducing the problems of durability.

Over the years (1, 2, 3) discussed the problems and the

methods on mechanism of durability. Damage evaluation

methods and effects on mortars and concrete exposed

to different percentages of different acids were conducted

(4, 5). The effect of pH and salt in 3 % solution of Na2SO

4

was evaluated on time period and conductivity (6).

Different fibers were researched and introduced leading

to the development of fiber reinforced concrete (7, 8, 9).

One such aim of this research which is a part of PhD work

were to study the effect of acids and salts using mixed

fibers in varying percentages in different total fiber mixes

by volume in solutions of 5 % H2SO

4, HCl and Na

2SO

4 on

the immersed specimens of mixed fiber reinforced

concrete. Weight, strength, pH and conductivity changes

against period of exposure were observed.

Experimental Investigation

The details of the materials used in the present

experimental investigation are as follows.

Cement:

OPC of 53 grade having specific gravity of 3.15 is used

Coarse Aggregate and Fine Aggregate

Machine crushed well graded angular granite aggregate

of size 20 mm from local source are used. The specific

gravity is 2.87. The fineness modulus is 6.92. River sand

Fibers

AR-

Glass

Density

in t/m3

2.6

Elastic

modulus

GPa

73

Tensile

strength

in MPa

1700

Diameter

in micron

14

Length

in mm

12

No. of

fibers in

million

kg

212

Table 1.Cem–FIL ARC14 306 HD having the following properties is used

RAnand

Text Box

Nina Concrete Systems Pvt Ltd

The Masterbuilder - February 2012 • www.masterbuilder.co.in120

locally available is used. The specific gravity is 2.5. The

fineness modulus is 2.62.

Glass Fiber

Steel Fiber

Monofilament Steel fibers of 1 mm diameter & aspect

ratio 55 is used.

Water

Locally available potable water is used n.

Concrete Mix

Grade

M25

Cement

in kg

400

Fine aggre-

gate in kg

640

Coarse aggre-

gate in kg

1200

Water cement

ratio

0.5

Mixing and casting

The dry aggregates were mixed first in the mixer. Then

one third water is sprinkled on the concrete and fibers are

sprinkled and then the remaining water is sprinkled. The

mixed mix is taken out and the specimens were casted in

moulds. Table vibration is given and the mould surfaces

are smooth finished. The different total fiber percentages

of 0.5, 0.75, 1.0 and 1.5 with five varying percentages of

mix fiber proportions in each total fiber percentage were

used to cast 160 numbers of specimens.

Acid and Salt solution

Sulphuric acid solution is made with 5 % acid in deionised

water and abt. 98 % LR, having specific gravity 1.835 and

molecular weight of 98.07. The molarity is 0.52 M.

Hydrochloric acid solution is made with 5 % acid in

deionised water and purity of 35-38 % LR, having specific

gravity 1.18 and molecular weight 36.46. The molarity is

1.37 M. Sodium sulphate solution is made with 5 % crystals

in deionised water having anhydrous purity 99 % LR and

molecular weight 142.04. The molarity is 0.36 M (50 gm +

975 ml to make 1000 ml solution)

Period of exposure

The observations were recorded at exposed periods of

the specimens in the solutions at 30 days, 60 days, 90

days, 120 days, 150 days and 180 days.

Testing Procedure

At the curing age of 28 days the specimens were weighed

and immersed in the made solutions of 5 percent acids

and salt. The weight losses at various periods of exposures

were recorded and at 180 days the specimens were tested

to compression for strength.

Results and Discussions

Weight effect

The control specimens without any fibers immersed in

the solution of 5 percent sulphuric acid was found to have

less weight loss than the specimens immersed in the same

solution with 100 percent glass fiber in a total fiber

percentage. The same trend was observed with different

total fiber percentages of 0.5, 0.75, 1.0 and 1.5 shown in

tables 3, 4 and figures 1, 2.

The specimens with decreasing glass fiber percentage

of 100 percent to zero percent in the mixed fiber in the

total fiber percentage exposed to the solution of 5 percent

sulphuric acid exhibited decreased weight loss. The

weight loss was observed to be minimum in the specimens

having 100 percent steel fiber. The same trend was

observed in the specimens with different total fiber

percentages of 0.5, 0.75, 1.0 and 1.5.

The maximum percentage loss was observed in the

specimens with 1.5 percentage total fiber exposed to the

sulphuric acid with increasing period of exposure from 30

days to 180 days. The same trend was observed in all the

specimens in the total fiber percentages of 0.5, 0.75, 1.0 and 1.5.

The control specimens without any fiber immersed in the

solution of 5 percent Hydrochloric acid was found to have

more weight loss compared to specimens with fiber. With

decreasing percentage of glass fiber in the mixed fiber

proportion in a total fiber percentage, the weight loss was

observed to increase and is maximum in the specimens

with 100 percent steel fiber. The same trend was observed

in the other specimens in all the other total fiber

percentages as shown in tables 5, 6 and figures 3, 4.

The percentage weight gain observed in the control

specimens immersed in the 5 percent sodium sulphate

S.No.

1

2

3

4

5

6

Mixed fiber (%)

G.F

0

100

75

50

25

0

S.F

0

0

25

50

75

100

% weight loss

at 30 days

4.78

5.09

3.61

3.38

2.56

2.35

% weight loss

at 60 days

5.88

6.52

4.15

3.75

3.43

2.72

% weight loss

at 90 days

7.11

7.56

5.14

4.2

3.99

3.21

% weight loss at

120 days

8.1

8.67

5.92

4.94

4.37

3.54

% weight loss at

150 days

8.8

9.94

6.98

5.67

5.05

4.17

% weight loss at

180 days

9.19

10.88

7.14

6.25

5.49

4.89

Table 3. Percentage weight loss in the specimens with 0.5 total fiber percentage exposed to 5 percent H2SO

4 solution.

Table 1.Cem–FIL ARC14 306 HD having the following properties is used

MFRC Experimental Study

www.masterbuilder.co.in • The Masterbuilder - February 2012 121

solution was observed to be minimum when compared

with all the other mixed fiber proportion in a total fiber

percentage. The maximum weight gain was observed to

be in 100 percent glass fiber proportion. With decreasing

glass fiber percentage the weight gain was observed to

be decreasing. With increasing exposed periods the

specimens exhibited increased weight gain. It was

observed that wit increase total percentages of fiber the

weight gain was decreasing. The same trend was

observed for all total fiber percentages as shown in tables

7, 8 and figures 5, 6.

S.No.

1

2

3

4

5

6

Mixed fiber (%)

G.F

0

100

75

50

25

0

S.F

0

0

25

50

75

100

% weight loss

at 30 days

4.78

5.7

4.02

3.69

3.49

2.93

% weight loss

at 60 days

5.88

6.7

4.91

4.41

4

3.56

% weight loss

at 90 days

7.11

8.48

5.99

5.01

4.59

4.03

% weight loss at

120 days

8.1

9.25

6.31

5.63

5.36

4.66

% weight loss at

150 days

8.8

10.09

7.09

6

5.53

5.35

% weight loss at

180 days

9.19

11

7.52

6.69

6.49

5.97

Table 4. Percentage weight loss in the specimens with 0.75 total fiber percentage exposed to 5 percent H2SO

4 solution.

Figure1. Percentage weight losses with 1.0 percentage total fiber exposed

in 5 percent H2SO

4 solution.

Figure2. Percentage weight losses with 1.5 percentage total fiber exposed

in 5 percent H2SO

4 solution.

Surface effect

Lesser texture deterioration in 75 % glass fiber and 25 %

steel fiber were observed compared to other mix

S.No.

1

2

3

4

5

6

Mixed fiber (%)

G.F

0

100

75

50

25

0

S.F

0

0

25

50

75

100

% weight loss

at 30 days

1.7

1.26

1.36

1.44

1.58

1.66

% weight loss

at 60 days

3.04

2.32

2.38

2.58

2.8

2.98

% weight loss

at 90 days

4.06

3.18

3.38

3.54

3.74

3.96

% weight loss at

120 days

5.7

3.78

4.08

4.38

4.72

5.42

% weight loss at

150 days

7.18

5.06

5.4

5.72

5.92

6.52

% weight loss at

180 days

7.72

5.94

6.28

6.58

6.84

7.18

Table 5. Percentage weight loss in the specimens with 0.5 total fiber percentage exposed to 5 percent HCl solution.

Figure 3. Percentage weight losse with 1.0 percentage total fiber exposed

in 5 percent HCI solution.

Figure 4. Percentage weight losse with 1.5 percentage total fiber exposed

in 5 percent HCI solution.

Figure 5. Percentage weight losse with 1.0 percentage total fiber exposed

in 5 percent Na2SO4 solution.

MFRC Experimental Study

The Masterbuilder - February 2012 • www.masterbuilder.co.in122

S.No.

1

2

3

4

5

6

Mixed fiber (%)

G.F

0

100

75

50

25

0

S.F

0

0

25

50

75

100

% weight loss

at 30 days

1.7

1.14

1.22

1.28

1.48

1.56

% weight loss

at 60 days

3.04

1.96

2.24

2.52

2.64

2.92

% weight loss

at 90 days

4.06

2.86

3.14

3.24

3.52

3.68

% weight loss at

120 days

5.7

3.44

3.64

3.96

4.48

4.88

% weight loss at

150 days

7.18

4.82

5.14

5.44

5.68

6.34

% weight loss at

180 days

7.72

5.42

5.72

5.84

6.52

6.86

Table 6. Percentage weight loss in the specimens with 0.75 total fiber percentage exposed to 5 percent HCl solution

S.No.

1

2

3

4

5

6

Mixed fiber (%)

G.F

0

100

75

50

25

0

S.F

0

0

25

50

75

100

% weight loss

at 30 days

0.24

0.46

0.38

0.32

0.28

0.26

% weight loss

at 60 days

0.27

0.52

0.48

0.4

0.34

0.29

% weight loss

at 90 days

0.34

0.62

0.59

0.52

0.43

0.38

% weight loss at

120 days

0.42

0.67

0.62

0.57

0.52

0.44

% weight loss at

150 days

0.46

0.75

0.7

0.63

0.58

0.5

% weight loss at

180 days

0.53

0.82

0.75

0.7

0.66

0.57

Table 7. Percentage weight gain in the specimens with 0.5 total fiber percentage exposed to 5 percent Na2SO

4 solution

S.No.

1

2

3

4

5

6

Mixed fiber (%)

G.F

0

100

75

50

25

0

S.F

0

0

25

50

75

100

% weight loss

at 30 days

0.24

0.52

0.46

0.4

0.31

0.28

% weight loss

at 60 days

0.27

0.6

0.54

0.49

0.47

0.39

% weight loss

at 90 days

0.34

0.73

0.64

0.58

0.54

0.43

% weight loss at

120 days

0.42

0.78

0.68

0.62

0.59

0.46

% weight loss at

150 days

0.46

0.88

0.79

0.72

0.69

0.56

% weight loss at

180 days

0.53

0.9

0.84

0.77

0.74

0.62

Table 8. Percentage weight gain in the specimens with 0.75 total fiber percentage exposed to 5 percent Na2SO4 solution

Figure 5. Percentage weight losse with 1.5 percentage total fiber exposed

in 5 percent Na2SO

4 solution.

proportions in the same total fiber percentages shown in

figure 7. The optimization in terms of surface deterioration

with fibers is seen at 1.0 % total fiber percentage. The

surface color of the specimens changed to whitish. The

overall deterioration is more and denseness is less

compared to the specimens exposed to hydrochloric acid

and sodium sulphate solutions.

The surface deterioration of the specimens immersed in

5 percent Hydrochloric acid solution is very much less

compared to the specimens exposed in sulphuric acid.

Brittleness of the surface is more compared to sodium

sulphate solution exposed specimens. The increasing

color change to red is observed with black patches with

increasing exposed period and denseness is reduced

but is better than sulphuric acid exposed specimens.

Lesser texture deterioration in 75 % glass fiber and 25 %

steel fiber were observed compared to other mix

proportions in the same and other total fiber percentages.

The glass fibers were less affected than steel fibers and

the discoloration of the specimens to red is concluded

Figure 7. Comparisons of surface deterioration of the specimens exposed to

sulphuric acid solution

MFRC Experimental Study

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due to dissolving of steel fibers or iron oxide as shown in

figure 8.

There was no deterioration of the surface of the specimens

exposed to 5 percent sodium sulphate solution. The salt

crystals deposits were observed on the surface as shown

in figure 9.

Figure 8. Deteriorated specimen exposed to 5 percent Hydrochloric acid solution

Strength effect

Compared to unexposed strength, the specimens

exposed to solution of sulphuric acid showed decreased

strength at all the total fiber percentages in the mixed

Figure 9. Surface deterioration of the specimens in solution of sodium sulphate

proportion in a total fiber percentage. The control

specimens showed lesser strength compared to all the

specimens with fibers. The maximum strength was

observed in specimens with 100 percent steel fiber. With

increase in total fiber percentages the strength was

observed to be increasing with maximum at 1.5 percent

total fiber as shown in table 9. In a total fiber percentage

the strength was found to be increasing as the glass fiber

percentage was decreasing and the same trend is

observed in all the total fiber percentages.

The specimens exposed to Hydrochloric acid solution

are observed to have decreased strength when compared

to unexposed specimens. Maximum strength was

observed in specimens with 100 percent steel fiber. With

decreasing glass fiber percentage in a total fiber

percentage, the strength was found to be increasing. The

control specimens are observed to have lesser strength

when compared to specimens with fibers. The same trend

was observed in all the total fiber percentages. The

strength loss was observed to be increasing with

maximum at 1.5 percent as shown in table 10.

The strength of the specimens exposed to solution of 5

percent sodium sulphate was found to be higher when

compared with unexposed specimens. The control

specimens without any fibers and the specimens with

fibers are observed to have more strength when compared

with unexposed specimens. With decreasing glass fiber

percentage the strength in the exposed specimens was

found to be increasing as shown in table 11. The minimum

strength was observed in the exposed specimens with

100 percent glass fiber. The maximum strength in the

exposed specimens was observed with 100 percent steel

fibers. Increase in strength was observed with increasing

total fiber percentages in the specimens exposed to

sodium sulphate solution.

pH and conductivity effect

With increasing period of exposure of the specimens, the

pH value of the sulphuric acid solution was increasing

compared to fresh solution without the exposed

specimens. The conductivity of the solution decreases

and was minimum at 180 days exposed age. With

increase in period of exposure of the specimens, the pH

value of the Hydrochloric acid solution was increasing

compared to fresh solution without the exposed

specimens. The conductivity of the solution decreases

and was minimum at 180 days exposed age. The pH and

conductivity of the solution of sodium sulphate with the

exposed specimens was observed to be increasing at

different exposed periods upto 180 days. The tables 12

and 13 show the results of pH and Conductivity. The

solution of Na2So

4 showed increase in alkalinity upto 180

days, with increase in both pH and conductivity indicating

strength gain. The acidic nature of the acid solutions was

observed to be decreasing with increasing period of

exposure of the specimens. The higher pH values of the

acids showed decrease in strength compared to

unexposed specimens, indicating a lesser acidic solution.

The conductivity suggests that the ions absorbed by the

specimens relates to decreasing level of acidity of the

solutions. High conductivity value gives less strength

change. Hence concentration of acids and their molarity

and normality are related with weight loss and strength

change.

MFRC Experimental Study

www.masterbuilder.co.in • The Masterbuilder - February 2012 125

Conclusions

The following conclusions are drawn based on the

experimental studies.

- The resistance of the control specimens without any

fiber to sulphuric acid is higher when compared with

100 percent glass fiber reinforced specimens and the

weight loss is more than two times to that of the

specimens with 100 percent steel fiber.

- The resistance of the specimens to sulphuric acid with

100 percent steel fiber is maximum when compared

to specimens without fiber and with other fiber

proportions.

- In the mixed fiber specimens, the proportion of 25

percent glass fiber and 75 percent steel fiber exhibited

higher resistance to sulphuric acid.

- The mixed fiber reinforced specimens and the

specimens with 100 percent steel fiber when

compared with control specimens exhibited more

resistance to the sulphuric acid and this is true at all

ages.

- The specimens in 75 % glass fiber and 25 percent

S.No.

1

2

3

4

5

6

Mixed fiber (%)

G.F

0

100

75

50

25

0

S.F

0

0

25

50

75

100

Unexposed strength at 28 days N/mm2

0.5

46.3

55.16

57.18

58.99

60.79

61.12

0.75

46.3

57.27

59.45

61.28

62.56

63.7

1.0

46.3

59.01

61.08

62.56

64.12

65.24

1.5

46.3

59.77

60.53

63.52

65.75

67.77

Exposed strength at 180 days N/mm2

0.5

14.15

14.52

16.14

16.95

19.17

20.12

0.75

14.15

16.34

17.83

19.44

20.29

21.72

1.0

14.15

18.3

19.26

21

22.64

25.47

1.5

14.15

20.63

21.47

23.79

25.14

26.58

Table 9. Strength losses in the specimens exposed in 5 percent H2SO

4 solution with different total fiber percentages.

S.No.

1

2

3

4

5

6

Mixed fiber (%)

G.F

0

100

75

50

25

0

S.F

0

0

25

50

75

100

Unexposed strength at 28 days N/mm2

0.5

46.3

55.16

57.18

58.99

60.79

61.12

0.75

46.3

57.27

59.45

61.28

62.56

63.7

1.0

46.3

59.01

61.08

62.56

64.12

65.24

1.5

46.3

59.77

60.53

63.52

65.75

67.77

Exposed strength at 180 days N/mm2

0.5

30.62

31.42

32.04

32.88

33.04

34.2

0.75

30.62

31.89

32.41

33.04

33.62

34.58

1.0

30.62

32.64

33.65

33.91

34.97

35.18

1.5

30.62

32.97

33.84

34.38

34.74

35.61

Table 10. Strength losses in the specimens exposed in 5 percent HCl solution with different total fiber percentages

S.No.

1

2

3

4

5

6

Mixed fiber (%)

G.F

0

100

75

50

25

0

S.F

0

0

25

50

75

100

Unexposed strength at 28 days N/mm2

0.5

46.3

55.16

57.18

58.99

60.79

61.12

0.75

46.3

57.27

59.45

61.28

62.56

63.7

1.0

46.3

59.01

61.08

62.56

64.12

65.24

1.5

46.3

59.77

60.53

63.52

65.75

67.77

Exposed strength at 180 days N/mm2

0.5

52.74

57.53

60.74

62.57

64.27

67.76

0.75

52.74

59.06

62.03

65.44

66.14

68.84

1.0

52.74

61.45

63.26

66.14

67.03

70.55

1.5

52.74

61.73

64.3

67.08

69.64

71.91

Table 11. Strength losses in the specimens exposed in 5 percent Na2SO

4 solution with different total fiber percentages

steel fiber in 1 % total fiber percentage exhibited

maximum resistance to sulphuric acid and this is the

optimisation.

- Compared to the unexposed specimens to the

sulphuric acid, the exposed specimens with fibers

have lower strength at all ages. The exposed

specimens with mixed fibers including specimens with

100 percent steel fiber have recorded better crushing

strength compared to exposed control specimens.

- The resistance of the control specimens without any

fibers to hydrochloric acid is lesser when compared

with all the fiber reinforced exposed specimens. The

weight loss is maximum in the control specimens at

the age of 180 days exposure.

- The resistance of the specimens to HCl acid with 100

percent glass fiber is maximum when compared to

specimens with other varying fiber proportions. In the

mixed fiber specimens, the proportion of 75 percent

glass fiber and 25 percent steel fiber exhibited higher

resistance to HCl acid. The fiber reinforced specimens

exposed to HCl acid exhibited more resistance when

compared to control specimens without any fiber in

MFRC Experimental Study

The Masterbuilder - February 2012 • www.masterbuilder.co.in126

terms of weight loss.

- With increasing total fiber percentage, the resistance

of the exposed specimens to HCL acid is increasing

upto 1.5 percent and this is true at all ages.

- The mixed fiber and the 100 percent steel fiber

reinforced exposed specimens to HCl acid exhibited

higher strength compared to exposed control

specimens at all ages.

- The resistance of the control specimens without any

fiber exposed to sodium sulphate solution is lesser

when compared with fiber reinforced specimens. The

weight gain is less when compared to specimens with

fiber.

- The 100 percent steel fiber reinforced specimen

exposed to sodium sulphate is more resistant when

compared to 100 percent glass fiber reinforced

specimens and the specimens with other mixed

proportion. The weight gain of all the specimens is

taking place and it is maximum in 1.5 percent at the

age of 180 days.

- The unexposed specimens with and without fiber

exhibited less strength compared to exposed

specimens with and without fiber. The strength of 100

percent steel fiber specimen is maximum when

exposed to sodium sulphate solution.

- With increasing period of exposure of the specimens

with and without fibers in acids, the pH of the sulphuric

acid is increasing and the conductivity values are

decreasing compared to fresh acid indicating

decreasing acidic nature of the acid with age. The

higher acidic nature has given higher deterioration,

more weight loss and less strength for the sulphuric

acid exposed specimens.

- The specimens exposed to hydrochloric acid exhibited

lesser weight loss compared to other acids and higher

strength due to the increasing values of pH and the

decreasing value of the conductivity. The low acidic

nature has given less weight loss and more strength

to the exposed specimens to HCl acid.

- The increases in values of pH and conductivity of

sodium sulphate solution have resulted in increased

strength at all ages of exposure when compared to

sulphuric acid and hydrochloric acid exposed

specimens. The higher alkalinity of the solutions gives

higher strength to the fiber reinforced specimens.

- The crushed specimens showed better bonding due

to the presence of fiber after exposure.

Acknowledgement

The authors wish to place on record the help provided by

the managements and the academic teaching and non

teaching faculties of Vasavi college of Engineering,

Ibrahimbagh, and Deccan college of Engineering and

Technology Darussalam, Hyderabad in the completion of

this project.

References

- Adam Neville March 2001, Consideration of durability of concrete

structures: Past, Present and Future, Materials and Structures/

Materiaux ET Constructions, Vol. 34, pp 114-118.

- O. Valenta 1970, From the 2nd RILEM Symposium Durability of

concrete-In Prague, Materiaux et Constructions Vol. 3-17, pp

333-345

- Miguel Angel Bermudez Odriozola, Pilar Alaejos Gutierrez, 2008,

Comparative study of different test methods for reinforced

concrete durability assessment in marine environment, Materials

and Structures, 41: 527-541.

- Marcos Lanzon.P.A.Garcia-Ruiz 2010 Deterioration and damage

evaluation of rendering mortars exposed to sulphuric acid,

Materials and Structures 43:417-427

- Pengfei Huang, Yiwang Bao, Yan Yao, 2005 Influence of HCl

corrosion on the mechanical properties of concrete Cement

and Concrete Research 35: 584-589

- Jeewoong Kim, C. Vipulanandan, 2003 Effect of pH, Sulfate

and Sodium on the EDTA titration of calcium, Cement and

Concrete Research 33: 621-627

- Fiber Concrete Materials, A report prepared by RILEM technical

committee 19 FRC, Vol 10-N 56-MATERIAUX ET

CONSTRUCTIONS, pp 103 - 120

- ACI 544.5R-10, Report on the Physical Properties and Durability

of Fiber Reinforced Concrete.

- ACI 544.2R-89, Measurement of Properties of Fiber Reinforced

Concrete.

- IS: 516-1959, Methods of Tests for Strength of Concrete

- IS 5816, 1976. Method of Test for Splitting Tensile Strength of

Concrete Cylinders. Bureau of Indian Standard, New Delhi, India.

S.No.

1

2

3

pH Values at Period of ExposureType of

Solutions

5 % H2SO

4

5 % HCL

5 % Na2SO

4

Fresh

0.78

0.52

7.40

30

Days

0.83

2.73

8.17

60

Days

0.85

2.98

8.28

90

Days

0.87

3.24

8.38

120

Days

0.90

3.55

8.67

150

Days

0.93

3.78

8.93

180

Days

0.98

3.94

9.42

Table 12. Comparison of pH of solutions at different exposed periods of the

specimens

Table 13. Comparison of conductivity of solutions at different exposed periods of

the specimens

S.

No.

1

2

3

Conductivity Values at Period of Exposure(mscm)Type of

Solutions

5 % H2SO

4

5 % HCL

5 % Na2SO

4

Fresh

120.7

181.4

29.6

30

Days

94

128.8

49.7

60

Days

78.5

121.2

84.3

90

Days

64.7

115.7

97.7

120

Days

42.1

52.7

110.1

150

Days

39.6

43.9

119.1

180

Days

22

34.4

122.8

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Recycling of Construction &Demolition Waste: An Overview

Mohan Ramanathan, B.Tech., M.S. (USA)

Managing Director, Advanced Construction Technologies

Construction activities generate over million

tones of construction and demolition (C&D)

materials each year. These materials contain

a lot of reusable materials. If not properly managed,

they will become wastes, a burden to the society, which

will be extremely expensive to handle and will occupy

precious landfill space. This paper contains an

overview of the concept on waste management and

how proper waste management plan at the life cycle

of construction can reduce its generation, maximize

its direct reuse, increase the opportunity for recycling

and reduce the need and hence the cost for its

disposal as waste.

Recycling can turn the otherwise waste materials into

usable products, which can help conserve our natural

resources for our next generations and for the

sustainable development of the society. However,

success on recycling takes time and requires a proper

waste management plan at global level and the

general acceptance of the recycled products. This

paper will cover some overseas experience and the

experience in India.

Construction activities generate huge amount of

construction and demolition (C&D) materials each

year. The activities include site formation, tunneling

works, demolition of building and structures,

Site Management Waste Recycling

www.masterbuilder.co.in • The Masterbuilder - February 2012 149

decoration and reconstruction works, new construction

and maintenance works. Most of these materials are inert

materials such as earth, rocks and concrete, which can

be reused or recycled. Even timbers and wooden

materials can be reused or recycled if properly handled.

In the old days, when the materials were scare and

expensive in comparison to labour costs, lots of these

C&D materials had been salvaged and reused through

balance cut and fill, rehabilitation, reclamation, reuse of

brick and masonry, reuse of timber and wood to its

maximum potential. With the prosperity and rapid

development of a society, the society has become more

and more extravagant and less concern on conservation

of natural resources. Factors contribute to this situation are.

- Lower cost in quarrying of natural resources due to

modern machines.

- Low import cost of aggregates from neighbouring

developing regions.

- Demolition of buildings and structures long before the

end of its designed or useful life.

- Base "use and throw way" habit.

- Tight development programme for quick financial

return.

- Improper or lack of waste management.

As a result, lots of natural resources were drained away as

waste and required extra expense and resource to handle

and accommodate. Worst still, it will not only create

environmental and social problems, the society will

consume the remaining natural resources at a much faster

rate than is necessary. There is therefore a need for proper

waste management for the sustainable development.

Strategy

In order to minimize the adverse impact, both social and

environmental, most developed countries have

formulated their own strategies on management of waste

at national level. Such measures include.

- Mandating adoption of waste management plan at

national level, such as in Germany, Denmark and Hong

Kong.

- Setting target on achievement on recycling by stages.

- Imposing heavy tax on waste disposal.

- Imposing aggregates tax to encourage use of

recycled aggregates

- Increasing effort in education and information on waste

reduction and recycling to identify and exploit the

opportunities of recycling and overcome the barriers

and obstacles due to conservatism.

Generally speaking, the following strategy in hierarchical

orders are adopted by most countries.

- Minimizing the generation of waste in the first instance.

- Reusing the C&D materials in its original from as far as

possible.

- Recycling with minimal input of energy.

- Disposing of the waste environmentally, with waste to

landfills.

Waste Management Plan

For successful implementation of the waste management

strategy, it is required to formulate, implement, monitor

and review of a Waste Management Plan during the whole

life cycle of the projects. In advance countries, such as

Germany and Denmark, Waste Management Plan has

not only established at corporation level and project level,

it has been extended to state level or even high to show

the determination and commitment on waste management.

In general, the waste management plan should cover

activities at all stages, from conceptual and planning

stages, through design and construction stages, and to

maintenance and reconstruction stages. Waste

minimization, reuse, recycling and disposal should be

well planned and implemented, monitored and reviewed

at all stages, with life cycle cost on waste disposal taken

into consideration.

In Hong Kong, the Government has issued technical

circular requiring the implementation of waste

management in public works projects. The Government

is also encouraging the private sector to adopt the same.

In addition, there is also drive to motivate financial

incentive on management and reduction of waste by

implementation of construction disposal charging

scheme.

Site Management Waste Recycling

The Masterbuilder - February 2012 • www.masterbuilder.co.in150

Waste Minimization

Minimization of waste should commence at the onset of

the project. This includes better planning layout,

balanced cut and fill, use of precast construction, reuse

and recycling of C&D materials on site with the minimal

import and export. For redevelopment, rehabilitation of

old building and structures should be considered during

town planning to increase its useful life without the need

for demolition. Demolition can also be avoided by

redesignating disused or no longer functioned buildings

and structures for appropriate usage. Adopting recyclable

materials at the onset of the projects will cut down overall

waste in the life cycle of the project. Further avoidance of

waste can be done by proper procurement, handling and

storing of construction materials on site during

construction. In addition, adopting selective demolition

and on-site sorting will maximize the potential for reuse

and recycling and hence reduction in waste. Systematic

and proper maintenance can slow down deterioration and

prolong the useful life of building and structures to delay

the process needed for reconstruction.

Reuse

In the old days, people had every endeavour to make the

best use materials available and had every incentive to

maximize the use of natural resources. In underdevelo-

ped countries, people treat every piece of masonry, brick

or tile, rock and crushed concrete as valuable. During

the demolition, they will take down the bricks and good

tiles carefully. striping out the mortar and properly stacked

aside for reuse later. Even in advance countries, wooden

doors can be carefully salvaged by adopting selection

demolition, with the salvaged doors for reuse or resale in

the 2nd hand market or 3rd or 4th world markets. Wooden

planks or timbers can also be trimmed to size for

appropriate reuse. Topsoil can be saved for gardening or

landscaping use, while earth or rubble can be reused in

site formation or reclamation if feasible.

Recycling

Apart from those valuable metals such as steel rebars

and aluminum window frames, which have high scrape

value, rubbles and demolished concrete can be

processed into recycled rockfill or aggregates for use in

construction. To avoid unnecessary waste of energy

resources, only those materials with marketable value

should be recycled. In most countries, 90% of the

demolition construction materials consist of concrete and

masonry, which are recyclable. Depending on the types

of construction, some buildings were made of mostly

masonry while some others were made mostly with

concrete. To avoid mixing recyclable materials with non-

recyclable one, it is recommended to separate them at

source by selective demolition and on-site sorting, as

sorting highly mixed materials at the receiving ends is

extremely expensive and not environmental friendly.

Recycling Practice

Although different countries adopt different practices to

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suit their own situations, the recycling practices can be

broadly classified in the following categories.

- Adopting on site recycling and reuse with minimal

import and export of construction materials for large

reconstruction projects.

Examples:

During the reconstruction of super highways (outbound)

in Germany, old concrete pavements were broken up and

processed at a pre-planned nearby recycling site, with

recycled aggregates used in producing concrete Grade

45 in an adjacent batching plant for use in new pavement

construction. The advantages of this arrangement are:

- Minimal export of waste and minimal import of raw

materials

- Minimal addition of traffic loading on existing busy

road networks.

- Energy saving due to reduction on fuel consumption

by lorries.

- Reduced noise and air pollution due to least generation

of traffics and fuel consumption.

- Maximization on the recycling potentials and values

due to no mixing of high quality demolished materials.

- Adopting on site crushing with recycled products used

in other projects or for re-sales.

- Collecting and stockpiling recyclable materials, then

hiring mobile crushers for processing.

- Establishing centralized recycling facilities.

- Establishing recycling facilities within landfill site, with

truck delivering C&D materials into the landfill site and

collecting recycled products at exit (e.g. Denmark)

Applications

Based on overseas experience and the experience in Hong

Kong, recycled aggregates have lots of applications,

running from high value applications such as use in

concrete production and manufacture of concrete paving

blocks and kerbs, to low end use as road sub-base

materials, rockfill, filters, pipe bedding, in-fill to stone

columns. However, the acceptance in high value

application is slow in most parts of the world due to

barriers and obstacles arising from conservatism and lack

of confidence in using new construction materials.

Fortunately, the American Concrete Institution (ACI) and

the European Union in the frame of RILEM" have been far-

sighted enough to establish ground works on sustainable

concrete with use of recycled aggregates. In Hong Kong

at least 4 ready mixed concrete producers have

experienced in producing recycled concrete up to Grade

40 for use in public works projects despite a slow start of

Site Management Waste Recycling

using recycled aggregates in concrete production.

Promotion

Acceptance on using recycled materials takes time and

promotion is required. Some overseas countries have

taken 10 to 15 to develop the markets on recycling. In

order to overcome the barriers and obstacles arising from

conservatism and lack of confidence, education and

information are the most important means to identify and

exploit the opportunity on promoting recycling. It is

necessary that the message and understanding of

recycling be discussed at universities, technical

institutes, amongst enterprises and public servants.

Information centre should be set up for the transparent

sharing of information and know-how on the development

and use of recycled aggregates. In Hong Kong, the

Government has taken the lead to liaise with the key

players including concrete producers, contractors,

academics and government department to collect

information such as test data and research results for

disseminating via the web connection

Conclusion

Natural resources are not unlimited and will be depleted

with time. Unnecessary wasting of natural resources should

be restricted and regulated. Formulating and

implementing proper waste management plan

throughout the life cycle of the projects can minimize

waste. With an integrated resource management, most

of the construction and demolition material can be

recycled and more natural resources can be conserved

for our next generations. The success of recycling and

using recycled materials in high value applications

requires promotion by means of education and information,

in addition to statutory rules from the concerned

authorities.

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The Masterbuilder - February 2012 • www.masterbuilder.co.in168

Deconstruction New Generation Tools

Next - Gen Diamond Toolsfor Nuclear Decommissioning

Mohan Ramanathan B.Tech M.S (USA)

Managing Director, Advanced Construction Technologies

Diamond tools are well proven cutting, drilling and

grinding technologies in many applications but

need to be specifically optimized and adapted

for the complex and varied structures of nuclear power

plant in view of decontamination and decommissioning.

The proper development and use of diamond tools in

these extreme and complex conditions can only be

achieved thanks to the combined talent of experienced

nuclear plant contractors, engineers, technicians,

operators of diamond tools, and the use of specialized

equipment.

Key Diamond Tool Applications for Decommissioning and

Decontamination of Nuclear Power Plant:

- Wet/dry concrete wall sawing (with remote control

system)

- Wet/dry wire cutting of concrete

- Wet/dry wire sawing of metal

- Wet/dry core drilling

- Grinding and leveling for surface preparation including

all edges

- Scraping for removing bituminous or neoprene glues

and all kinds of coatings

- Shaving for horizontal and vertical surfaces and

ceilings

Each situation requires a detailed feasibility study and

engineering report to select the optimal work method

and answer concerns about safety, time to completion

and waste volume.

Examples of Nuclear Industry Requirements:

"Camel Tools" (minimal water supply to limit water / mud

collection and decontamination).

- 100% dust collection

- Fast and easy change of tools

- Remote control systems

- High performances even in the strongest reinforced

concretes

- Restricted presence of operators in contaminated

areas

- Unquestionable reliability of the tools and equipment.

Diamond tools are well proven cutting, drilling and

grinding technologies in many applications but need to

be specifically optimized and adapted for the complex

and varied structures of nuclear power plant in view of

decontamination and decommissioning.

The proper development and use of diamond tools in

these extreme and complex conditions can only be

achieved thanks to the combined talent of experienced

nuclear plant contractors, engineers, technicians,

operators of diamond tools, and the use of specialized

equipment.

Each case requires a detailed feasibility study and

engineering report to develop the optimal solutions.

Safety issues, reduction of vibrations and sound level,

water waste limitation, 100% collection of the dust and

debris have become the key requirement for many

industries.

With R&D, testing facilities and a flexible diamond tool

production unit, all situated in Europe, they have the

capability to customize tools to the specific needs of any

demanding job. We have the expertise in all the different

diamond tool technologies and can serve as consultants

to identify the best technology for any given situation.

www.masterbuilder.co.in • The Masterbuilder - February 2012 169

Key Applications:

Wet / Dry Concrete Diamond Wall Sawing

Wall sawing with HF saw head and EFT diamond blade

- It is possible to combine wall sawing with a remote

control system

- The very thin cutting width results in reduced waste

production

- Extremely fast cut: up to 3.5 m²/h

- Cutting blades made for cutting any concrete even

heavily reinforced

- Silent blades are available (-8 to 10 dBA)

- Extremely high output (high segments for extended

autonomy) resulting in less intervention for changing

tools: from 25 to 80 m².

- Possible to customize a tool very quickly according to

the needs of any specific jobsite

Wet / Dry Diamond Wire Cutting of Concrete

Wire sawing with vacuum brazed diamond cable

- The wire cutting process allows for unlimited cutting

depth and length

- Very low sound level

- Very limited debris creation

- Low vibration: more comfort for the operator, less

disturbance for the surrounding structures

- A very large variety of materials, as well as mixed and

heterogeneous materials can be cut

- Very high flexibility in the positioning of the wire saw,

- Unusual configurations and difficult access areas are

easily and safely cut without removing obstructing

objects

- Underwater cuts for bridge and dam repairs, as well

as for offshore rig decommissioning and anywhere

where cutting underwater is needed

- Remote cutting can be performed in hazardous or

radioactive areas where direct access to the cut is

impractical or dangerous.

- Dry cutting with electroplated and vacuum-brazed

diamond beads

- Fast cut: 0.5 to 2.5 m²/h

- Long tool life: 1.0 to 3.0 m²/lm

- Technical assistance for selecting and setting up of

system

Wet / Dry Diamond Wire Sawing of Metal

Wire cutting of steel generator mock-up with vacuum brazed diamond wire

- Able to cut 100% carbon steel, stainless steel, cast

iron, any metal

- Underwater cuts can be made where necessary

- Remote cutting can be performed in hazardous or

radioactive areas where direct access to the cut is

impractical or dangerous

- Very high flexibility in the positioning of the wire saw,

- Dry or wet cutting

- Technical assistance for selecting and setting up of

system

Deconstruction New Generation Tools

The Masterbuilder - February 2012 • www.masterbuilder.co.in170

- Cutting speed 100 to 800 cm²/h depending on cut

configuration.

Wet/Dry Core Drilling

Core drilling with Raidor self-centering segments in reinforced flint concrete

- Micro percussion: New patented dry core drilling

system for cutting highly reinforced concrete, allowing

for extra heat evacuation

- Self-sharpening and self-centering segments to make

drilling and especially remote controlled drilling easy

- Possibility to drill several meters deep

- Customized drill bits and tool mounting possible in

very short lead times

Diamond Grinding and Leveling for Surface PreparationIncluding all Edges

Floor grinding with fan-shaped diamond plate

- Exclusive system (machine and tools)

- Works right up to the wall, columns and edges thanks

to the lateral shift mechanism and mobile cover

- Very low sound level

- Very limited vibration level

- The specific designed " Fan-Shaped " plate initiates

the dust suction in order to optimize the action of the

dust collector

- Possible to use a longer hose ( for a larger autonomy

on the work site)

- Eliminates cleaning of the floor and improves the

confinement of residue

- Compact and robust machine is easy to move and

transport

- The machine ergonomics makes the utilization easy

and comfortable for the operators

- Design of the machine improves the evacuation of

residue and reduces the risk of clogging in the hose

Diamond Scraping for Removing BituminousorNeoprene Glues and all Kinds of Coatings

Floor scraping of bituminous coating with single head grinder

- Dual-Action tools: Scrape and Clean in one Operation

- Patented Design with Optimal Functionality

- The sloping sides of the diamond segments are cutting

and self-sharpening making it possible to enter below

the surface covering; shaving or "slicing" off the coating

- The flat base of the diamond segment rectifies the

surface in the same operation

- Removing entire shavings reduces the dust pollution

to a minimum, improving the work conditions for the

operator as well as other people on or near the job

site. With dangerous surface materials, this also

minimizes the risk of creating toxic dust.

Deconstruction New Generation Tools

RAnand

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Cosmos Construction Machineries & Equipments Pvt.Ltd

The Masterbuilder - February 2012 • www.masterbuilder.co.in172

- Surfacing action emits less decibels, resulting in a

more convivial work environment.

Dust-Collection Systems

Different dust-collection systems are available and

adapted to the technology and power required.

- Special drums available on request in any depth and

length

- No scabling, no scarifying, no vibration

- Smooth surface

Author’s Bio

ACT is a company credited with introducing several new demolition

techniques in the country. A brainchild of Mr.Mohan Ramanathan,

popularly referred to as the 'Demolition Man' of India, the company

has grown on to become the preferred choice of a wide range of

clients. Mr. Mohan Ramanathan, who completed his Masters in

Civil Engineering from the University of Illinois, U.S.A, following his

Bachelor's Degree in Civil Engineering from the Indian Institute of

Technology (IIT)- Madras, has taken ACT from strength to strength.

The firm is a licensed subsidiary of Controlled Demolition

International, USA (CDI).

Vacuum cleaner with HEPA filter

Ceiling cleansing with D:250 grinding plate

- Primary filters of PTFE

- Secondary cartridges for

absolute filtration

- HEPA filters available for most

dust collection models

- Bagging systems

- Cyclonic and pre-separator

units for capturing and

immediately bagging of the

heavier debris

Diamond Shaving for Horizontaland Vertical Surfaces andCeilings

- Shaving off up to 100 mm deep

using a multitude of solutions

Deconstruction New Generation Tools

RAnand

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Reliance Industries Ltd

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Cosmos Sales Corporation

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Rapid Cutting Technologies

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Roof India '2012

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IQPC (Cost Effective Sustainable Design Construction)

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MB Subscription Form

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Contract Management Seminar (IITarb)

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India Facilities Management Summit 2012

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Instruct

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Baicon 2012

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MB Corporate

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Modern Formwork Systems

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Modern Formwork Systems

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(Dr. Fixit) Pidilite Industries Ltd.

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Chowgule Construction Technologies