Strength and durability of concrete with crushed sand

B Balapgol Indian Institute of Technology Bombay India S A Kulkarni Indian Institute of Technology Bombay India K M Bajoria Indian Institute of Technology Bombay India

27th Conference on OUR WORLD IN CONCRETE amp STRUCTURES 29 - 30 August 2002

Singapore

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2m Conference on OUR WORLD IN CONCRETE amp STRUCTURES 29 - 30 August 2002 Singapore

Strength and durability of concrete with crushed sand

B Balapgol Indian Institute of Technology Bombay India 5 A Kulkarni Indian Institute of Technology Bombay India K M Bajoria Indian Institute of Technology Bombay India

Abstract This paper presents the results of an experimental study on strength and durability

of concrete with crushed basalt stone fine aggregates as a substitute to diminishing natural sand The strength and durability properties of concrete viz compressive strength flexural strength and permeability of hardened concrete were investigated An experimental study was performed to observe the performance of concrete incorporating crushed basalt stone fine aggregates replacing the natural sand The test results indicate that the performance of concrete with crushed basalt stone fine aggregates were excellent The compressive strength of concrete for different grades increased from 8 to 26 the flexural strength was increased from 1 to 5 and coefficient of permeability was decreased significantly The test results indicated that strength and durability of concrete would be better with crushed sand replacing natural sand

1 Introduction The natUral sand is one of the main constituents of the concrete making about 35 of volume of

concrete used in building construction industry It is mainly excavated from the riverbeds Due to the construction of dams on rivers these natural resources are erasing fast In hilly areas and other such places where sand is not abundantly available this becomes a good substitute Natural sand always contains high percentages of inorganic salts of chlorides sulphates and other deleterious organic salts and impurities Chlorides and sulphates adversely affect the strength and durability of concrete and reinforcing steel thereby reducing life of the structure

Due to excessive excavation silt in natural sand has been found more in volume The salt percentage further increases in rainy season Excessive silt causes reduction in strength of concrete affecting durability Crushed sand is different in shape grading and content of very fine sand compared with river sand and it is well known that the material properties of crushed sand concrete are also different from those of river sand concrete [26] It is also responsible for shrinkage cracks in concrete works Thus the use of crushed sand as a substitute to the diminishing natural sand has become essential keeping in view of technical commercial and environmental requirements

There is a little available published data on the use of crushed sand as a SUbstitute to natural sand Ahmed et al in 1989 have studied the performance of concrete with limestone crushed sand as a substitute to the natural sand The results indicated that the concrete with crushed sand improved the physical properties of concrete [1] Sangamnerkar in 1999 reported that the dust content upto 10 as a partial replacement of fine aggregates improved the strength properties of concrete [2]

179

The investigation presented here in evaluates the performance of hardened concrete with crushed basalt stone fine aggregates as a substitute to the natural sand The experimental work was carried out on four concrete mixtures to study compressive strength flexural strength and permeability of concrete

2 Materials properties The constituents of concrete were tested as per Indian Standards [45] are summarized as follows

The properties of the materials used in the experimental work are given below

21 Cement The Birla Super ordinary Portland cement of 53 Grade is used

Specific gravity = 315 Fineness modulus =30663 cm 3 gm Consistency = 312 Initial setting time =200 minutes Final setting time = 600 minutes Soundness of cement =1 mm Compressive strength of cement 3 days= 3101 Nmm 2 7 days = 4898 Nmm 2

28 days= 6462 Nmm 2

22 Fine Aggregates Crushed basalt stone passing 475 mm sieve is used

Specific gravity =270 Fineness modulus =326 Water absorption =490 Free surface water =191 Bulk density =175 gmcm3

Bulking =80

23 Course Aggregates Crushed basalt stone passing through 25 mm and retaining on 475 mm sieve is used

a) 10 mm size aggregates Specific gravity = 301 Fineness modulus =210 Water absorption =162 Free surface water =140 Bulk density = 142 gm I cm 3

b) 20 mm size aggregates Specific gravity = 301 Fineness modulus =355 Water absorption =162 Free surface water =140 Bulk density = 148 gm I cm 3

Super plasticizer = MC-Bauchemic Zentrament FBV Drinking water is used for preparation of concrete

3 Testing program and results A total of eight mixes were prepared and studied to investigate the properties of concrete with

crushed basalt fine aggregates and natural sand Four mixes with crushed stone fine aggregates and four mixes with natural sand called control mixes were prepared The concrete mixes were made with watershyto-cement ratios of 038041055 and 060

The experimental study was carried out on specimens of four concrete mixes with crushed sand and 10 stone dust as part replacement to crushed sand and the test results were compared with corresponding four control specimens of concrete mixes having same proportions of constituents with natural sand The mix proportions designed as per Indian Standards [3] For comparison of behavior of natural sand and crushed sand natural sand was sieved and used in the same proportions as the percentages of fraction observed in crushed sand The gradation of aggregates is reported in Table no 1 The course lt3ggregates crushed sand and natural sand were separated into different size fractions and recombined to a specific gradation as shown in Table no1 The other constituents of concrete viz cement course aggregates plasticizer water-to-cement ratios were kept same for each concrete mix and corresponding control mix The adopted mix proportions for four grades of mixes are summarized in Table no2 The required slump of concrete was obtained by using super plasticizer FBV Zentrament as percent of weight of cement The concrete mixes were proportioned to have slump within permissible limits of Indian Standards [3] The following tests were conducted to study the strength and durability of concrete

180

2m Conference on OUR WORLD IN CONCRETE amp STRUCTURES 29 - 30 August 2002 Singapore

Strength and durability of concrete with crushed sand

B Balapgol Indian Institute of Technology Bombay India 5 A Kulkarni Indian Institute of Technology Bombay India K M Bajoria Indian Institute of Technology Bombay India

Abstract This paper presents the results of an experimental study on strength and durability

of concrete with crushed basalt stone fine aggregates as a substitute to diminishing natural sand The strength and durability properties of concrete viz compressive strength flexural strength and permeability of hardened concrete were investigated An experimental study was performed to observe the performance of concrete incorporating crushed basalt stone fine aggregates replacing the natural sand The test results indicate that the performance of concrete with crushed basalt stone fine aggregates were excellent The compressive strength of concrete for different grades increased from 8 to 26 the flexural strength was increased from 1 to 5 and coefficient of permeability was decreased significantly The test results indicated that strength and durability of concrete would be better with crushed sand replacing natural sand

1 Introduction The natUral sand is one of the main constituents of the concrete making about 35 of volume of

concrete used in building construction industry It is mainly excavated from the riverbeds Due to the construction of dams on rivers these natural resources are erasing fast In hilly areas and other such places where sand is not abundantly available this becomes a good substitute Natural sand always contains high percentages of inorganic salts of chlorides sulphates and other deleterious organic salts and impurities Chlorides and sulphates adversely affect the strength and durability of concrete and reinforcing steel thereby reducing life of the structure

Due to excessive excavation silt in natural sand has been found more in volume The salt percentage further increases in rainy season Excessive silt causes reduction in strength of concrete affecting durability Crushed sand is different in shape grading and content of very fine sand compared with river sand and it is well known that the material properties of crushed sand concrete are also different from those of river sand concrete [26] It is also responsible for shrinkage cracks in concrete works Thus the use of crushed sand as a substitute to the diminishing natural sand has become essential keeping in view of technical commercial and environmental requirements

There is a little available published data on the use of crushed sand as a SUbstitute to natural sand Ahmed et al in 1989 have studied the performance of concrete with limestone crushed sand as a substitute to the natural sand The results indicated that the concrete with crushed sand improved the physical properties of concrete [1] Sangamnerkar in 1999 reported that the dust content upto 10 as a partial replacement of fine aggregates improved the strength properties of concrete [2]

179

The investigation presented here in evaluates the performance of hardened concrete with crushed basalt stone fine aggregates as a substitute to the natural sand The experimental work was carried out on four concrete mixtures to study compressive strength flexural strength and permeability of concrete

2 Materials properties The constituents of concrete were tested as per Indian Standards [45] are summarized as follows

The properties of the materials used in the experimental work are given below

21 Cement The Birla Super ordinary Portland cement of 53 Grade is used

Specific gravity = 315 Fineness modulus =30663 cm 3 gm Consistency = 312 Initial setting time =200 minutes Final setting time = 600 minutes Soundness of cement =1 mm Compressive strength of cement 3 days= 3101 Nmm 2 7 days = 4898 Nmm 2

28 days= 6462 Nmm 2

22 Fine Aggregates Crushed basalt stone passing 475 mm sieve is used

Specific gravity =270 Fineness modulus =326 Water absorption =490 Free surface water =191 Bulk density =175 gmcm3

Bulking =80

23 Course Aggregates Crushed basalt stone passing through 25 mm and retaining on 475 mm sieve is used

a) 10 mm size aggregates Specific gravity = 301 Fineness modulus =210 Water absorption =162 Free surface water =140 Bulk density = 142 gm I cm 3

b) 20 mm size aggregates Specific gravity = 301 Fineness modulus =355 Water absorption =162 Free surface water =140 Bulk density = 148 gm I cm 3

Super plasticizer = MC-Bauchemic Zentrament FBV Drinking water is used for preparation of concrete

3 Testing program and results A total of eight mixes were prepared and studied to investigate the properties of concrete with

crushed basalt fine aggregates and natural sand Four mixes with crushed stone fine aggregates and four mixes with natural sand called control mixes were prepared The concrete mixes were made with watershyto-cement ratios of 038041055 and 060

The experimental study was carried out on specimens of four concrete mixes with crushed sand and 10 stone dust as part replacement to crushed sand and the test results were compared with corresponding four control specimens of concrete mixes having same proportions of constituents with natural sand The mix proportions designed as per Indian Standards [3] For comparison of behavior of natural sand and crushed sand natural sand was sieved and used in the same proportions as the percentages of fraction observed in crushed sand The gradation of aggregates is reported in Table no 1 The course lt3ggregates crushed sand and natural sand were separated into different size fractions and recombined to a specific gradation as shown in Table no1 The other constituents of concrete viz cement course aggregates plasticizer water-to-cement ratios were kept same for each concrete mix and corresponding control mix The adopted mix proportions for four grades of mixes are summarized in Table no2 The required slump of concrete was obtained by using super plasticizer FBV Zentrament as percent of weight of cement The concrete mixes were proportioned to have slump within permissible limits of Indian Standards [3] The following tests were conducted to study the strength and durability of concrete

180

The investigation presented here in evaluates the performance of hardened concrete with crushed basalt stone fine aggregates as a substitute to the natural sand The experimental work was carried out on four concrete mixtures to study compressive strength flexural strength and permeability of concrete

2 Materials properties The constituents of concrete were tested as per Indian Standards [45] are summarized as follows

The properties of the materials used in the experimental work are given below

21 Cement The Birla Super ordinary Portland cement of 53 Grade is used

Specific gravity = 315 Fineness modulus =30663 cm 3 gm Consistency = 312 Initial setting time =200 minutes Final setting time = 600 minutes Soundness of cement =1 mm Compressive strength of cement 3 days= 3101 Nmm 2 7 days = 4898 Nmm 2

28 days= 6462 Nmm 2

22 Fine Aggregates Crushed basalt stone passing 475 mm sieve is used

Specific gravity =270 Fineness modulus =326 Water absorption =490 Free surface water =191 Bulk density =175 gmcm3

Bulking =80

23 Course Aggregates Crushed basalt stone passing through 25 mm and retaining on 475 mm sieve is used

a) 10 mm size aggregates Specific gravity = 301 Fineness modulus =210 Water absorption =162 Free surface water =140 Bulk density = 142 gm I cm 3

b) 20 mm size aggregates Specific gravity = 301 Fineness modulus =355 Water absorption =162 Free surface water =140 Bulk density = 148 gm I cm 3

Super plasticizer = MC-Bauchemic Zentrament FBV Drinking water is used for preparation of concrete

3 Testing program and results A total of eight mixes were prepared and studied to investigate the properties of concrete with

crushed basalt fine aggregates and natural sand Four mixes with crushed stone fine aggregates and four mixes with natural sand called control mixes were prepared The concrete mixes were made with watershyto-cement ratios of 038041055 and 060

The experimental study was carried out on specimens of four concrete mixes with crushed sand and 10 stone dust as part replacement to crushed sand and the test results were compared with corresponding four control specimens of concrete mixes having same proportions of constituents with natural sand The mix proportions designed as per Indian Standards [3] For comparison of behavior of natural sand and crushed sand natural sand was sieved and used in the same proportions as the percentages of fraction observed in crushed sand The gradation of aggregates is reported in Table no 1 The course lt3ggregates crushed sand and natural sand were separated into different size fractions and recombined to a specific gradation as shown in Table no1 The other constituents of concrete viz cement course aggregates plasticizer water-to-cement ratios were kept same for each concrete mix and corresponding control mix The adopted mix proportions for four grades of mixes are summarized in Table no2 The required slump of concrete was obtained by using super plasticizer FBV Zentrament as percent of weight of cement The concrete mixes were proportioned to have slump within permissible limits of Indian Standards [3] The following tests were conducted to study the strength and durability of concrete

180

I ra a Ion 0 fA bTa ble no 1 G d t g_grega es )Y sieve analysIs Course Aggregates Natural Sand Crushed Sand

125 mm passing 25 mm passing Sieve size

(mm)

Cumulative retained

Sieve size

Cumulative retainedSieve

size Cumulative retained

Sieve size

Cumulative retained

125 00 25 00 475 1520 475 040

10 406 20 6504 236 3260 236 500

63 702 16 92 08 118 6910 118 5960

475 988 125 9852 060 8630 060 7870

Pan 1000 10 9986 030 9630 030 8910

-shy -shy 63 100 015 9910 015 9340

-shy -shy -shy -shy pan 100 pan 100

Fineness modulus

=210

Fineness modulus

=355

Fineness modulus

=326

Fineness modulus

=399

Table no 2Adopted mixture proportions for different grades of concrete

Mixture No Cement Crushed Course Aggregates WIC Ratio Plasticizer Sand by wt of

10 mm 20 mm cement

175 249 M15 1 35

424 060 15

155 222 M20 1 292

377 055 15

094 214 M35 1 158

368 041 27

089 209 M40 1 145

298 038 27

31 Compressive strength The compressive strength of the concrete was determined in accordance with Indian Standards [4]

To find compressive strength 30 cubes of size 150 x 150 x150 mm for each of eight mixes were casted The cube specimens were tested under uniaxial compression The average compressive strength results are reported at the age of 7 days and 28 days in Table no3

32 Flexural strength The flexural strength of concrete was determined by bending test in accordance with Indian

Standards [4] To find flexural strength three beam specimens of size 700 x 150 x150 mm for each of eight mixes were tested after 7 days and 28 days curing under universal testing machine with two-point loading The average flexural strengths for concrete with crushed sand and natural sand were reported in Table 4

181

Mixture no Compressive Strength Flexural Strength Permeability

(Nmm2) (Nmm2) (msec)

(x 10-8 )

7 Days 28 Days 7 Days 28 Days

M15-N 1384 2091 283 422 -shy

M15-C 1653 2263 287 426 176

M20-N 2194 3276 298 496 -shy

M20-C 2700 3704 306 512 148

M35-N 2330 3474 289 422 -shy

M35-C 3048 4185 298 426 126

M40-N 2553 3800 376 541 -shy

M40-C 35 84 4784 386 571 119

Table no 3 Constituents of Concrete for specimens ( per one cu m)

Mixture No

Cement (N)

Fine Aggregates

(N)

Course Aggregates (N)

ActualW ater

(N)

Stone Dust

(N)

Plasticizer

(N)

Natural Sand

Crushed Sand

20 mm 10 mm

M15-N 25506 89327 -shy 63522 44676 1829 -shy 3826

M15-C 25506 -shy 80400 63522 44676 1829 8929 3826

M20-N 29430 85887 -shy 65433 45657 1911 -shy 4415

M20-C 29430 -shy 77298 65433 45657 1911 858 9 4415

M35-N 41693 66008

-shy

-shy 89301 39028 1901 -shy 11260

M35-C 41693 59400 89301 3902 8 1901 858 9 11260

M40-N 43164 62955 -shy 90030 38028 1820 -shy 11650

M40-C 43164 -shy 56659 90030 38028 1820 6296 11650 Where M15-N represents mixture with natural sand and M15-C with crushed sand

Table no 4Compresslve s reng th flexuraI t and ffIClent 0 fJ)ermeablts reng th coe Il

aT b Ie no 5Variation 0 f compressive strenRt h and flexura strenRt h

Mixture No Percent increase in compressive Percent increase in flexural strength strenf th

7 Days 28 Days 7 Days 28 Days

M15-C 1944 823 141 095

M20-C 2306 1307 268 323

M35-C 3082 2047 311 332

M40-C 4038 2590 348 555

182

33 Permeability The permeability of concrete is related to durability of concrete in terms of its resistance against

progressive determination under exposure to sever climatic conditions and leaching due to prolonged seepage of water The permeability is measured in terms of coefficient of permeability by permeability test apparatus in accordance with Indian Standards [5] To find coefficient of permeability of hardened concrete a cube specimen of size 150 x 150 x 150 mm for each of eight mixes were casted The specimens were subjected to a known hydraulic pressure from one side in a permeability test apparatus after 28 days of curing Measuring the quantity of water percolated through it in 100 hours the coefficient of permeability were calculated and reported in Table 4

60

_ 50

0 ~ 40 c en c 30 agt (f)

ci 20 E 0

bull bull 1

-+-7 Day-N 7 Day- C

u 10

1-- 28 Day-N 1 --- 28 Day-C I

0 M15 M20 M35 M40

Grade of Concrete

4 Discussions 1 There was significant increase in compressive strength of concrete with crushed sand (refer Table 4

and Fig 1) 2 The compressive strength was increased by 1944 to 4038 at 7 -day age and increased by 833

to 259 at 28-day age as the grade of concrete mixes were increased (refer Table 5) 3 There was significant gain in compressive strength at early age (Fig 1)

4 The concrete mixes with crushed sand experienced marginal increase in the flexural strength (refer Table noA)

5 The flexural strength was increased by 141 to 348 at 7 day age and increased by 095 555 at 28 day age as the grade of concrete mix increased (refer Table no 5)

6 The coefficient of permeability of concrete was gradually decreased from 176 x 108 ms to 119 x10-8

ms as the grade of concrete mix increased (refer Table no 4 and fig 2)

5 Conclusions

183

An experimental study was performed to examine the strength and durability of concrete with crushed sand as replacement to the natural sand The data assembled during the course of investigation lead to the following conclusions bull The performance of concrete with crushed sand was excellent There was an increase in

compressive strength about 8 to 26 and flexural strength about 1 to 5 with as the grade of concrete mix increased

bull The concrete with crushed sand performed better than concrete with natural sand as the grade of concrete mix increased

bull The flexural strength of concrete with crushed sand was marginally increased on the strength of concrete with natural sand

bull The permeability of concrete decreased as the grade of concrete mix increased The concrete with crushed sand was found to be stronger and durable The crushed sand may be used as a substitute to natural sand

References 1 Ahmed A E and EI Kourd A A 1989 Properties of concrete incorporating natural sand and

crushed stone very fine sand American Concrete Journal 86(4)417-424 2 Celik T and Marar K 1996 Effect of crushed stone dust on some properties of concrete Cement

and Concrete Research 26(7) 1121-1130 3 Indian Standard code of practice for Recommended Guidelines for concrete mix-design I S

10262-1982 Bureau of Indian Standards New Delhi 4 Indian Standard code of practice for Methods of Test for Strength of Concrete I S 516-1959

Bureau of Indian Standards New Delhi 5 Indian Standard code of practice for plain and reinforced concrete I S 456-2000 Bureau of

Indian Standards New Delhi 6 Kim J K Lee C S Park C K and Eo S H 1997 The fracture characteristics of crushed lime

stone sand concrete Cement and Concrete Research 27( 11) 1719-1729

184

Mixture no Compressive Strength Flexural Strength Permeability

(Nmm2) (Nmm2) (msec)

(x 10-8 )

7 Days 28 Days 7 Days 28 Days

M15-N 1384 2091 283 422 -shy

M15-C 1653 2263 287 426 176

M20-N 2194 3276 298 496 -shy

M20-C 2700 3704 306 512 148

M35-N 2330 3474 289 422 -shy

M35-C 3048 4185 298 426 126

M40-N 2553 3800 376 541 -shy

M40-C 35 84 4784 386 571 119

Table no 3 Constituents of Concrete for specimens ( per one cu m)

Mixture No

Cement (N)

Fine Aggregates

(N)

Course Aggregates (N)

ActualW ater

(N)

Stone Dust

(N)

Plasticizer

(N)

Natural Sand

Crushed Sand

20 mm 10 mm

M15-N 25506 89327 -shy 63522 44676 1829 -shy 3826

M15-C 25506 -shy 80400 63522 44676 1829 8929 3826

M20-N 29430 85887 -shy 65433 45657 1911 -shy 4415

M20-C 29430 -shy 77298 65433 45657 1911 858 9 4415

M35-N 41693 66008

-shy

-shy 89301 39028 1901 -shy 11260

M35-C 41693 59400 89301 3902 8 1901 858 9 11260

M40-N 43164 62955 -shy 90030 38028 1820 -shy 11650

M40-C 43164 -shy 56659 90030 38028 1820 6296 11650 Where M15-N represents mixture with natural sand and M15-C with crushed sand

Table no 4Compresslve s reng th flexuraI t and ffIClent 0 fJ)ermeablts reng th coe Il

aT b Ie no 5Variation 0 f compressive strenRt h and flexura strenRt h

Mixture No Percent increase in compressive Percent increase in flexural strength strenf th

7 Days 28 Days 7 Days 28 Days

M15-C 1944 823 141 095

M20-C 2306 1307 268 323

M35-C 3082 2047 311 332

M40-C 4038 2590 348 555

182

33 Permeability The permeability of concrete is related to durability of concrete in terms of its resistance against

progressive determination under exposure to sever climatic conditions and leaching due to prolonged seepage of water The permeability is measured in terms of coefficient of permeability by permeability test apparatus in accordance with Indian Standards [5] To find coefficient of permeability of hardened concrete a cube specimen of size 150 x 150 x 150 mm for each of eight mixes were casted The specimens were subjected to a known hydraulic pressure from one side in a permeability test apparatus after 28 days of curing Measuring the quantity of water percolated through it in 100 hours the coefficient of permeability were calculated and reported in Table 4

60

_ 50

0 ~ 40 c en c 30 agt (f)

ci 20 E 0

bull bull 1

-+-7 Day-N 7 Day- C

u 10

1-- 28 Day-N 1 --- 28 Day-C I

0 M15 M20 M35 M40

Grade of Concrete

4 Discussions 1 There was significant increase in compressive strength of concrete with crushed sand (refer Table 4

and Fig 1) 2 The compressive strength was increased by 1944 to 4038 at 7 -day age and increased by 833

to 259 at 28-day age as the grade of concrete mixes were increased (refer Table 5) 3 There was significant gain in compressive strength at early age (Fig 1)

4 The concrete mixes with crushed sand experienced marginal increase in the flexural strength (refer Table noA)

5 The flexural strength was increased by 141 to 348 at 7 day age and increased by 095 555 at 28 day age as the grade of concrete mix increased (refer Table no 5)

6 The coefficient of permeability of concrete was gradually decreased from 176 x 108 ms to 119 x10-8

ms as the grade of concrete mix increased (refer Table no 4 and fig 2)

5 Conclusions

183

An experimental study was performed to examine the strength and durability of concrete with crushed sand as replacement to the natural sand The data assembled during the course of investigation lead to the following conclusions bull The performance of concrete with crushed sand was excellent There was an increase in

compressive strength about 8 to 26 and flexural strength about 1 to 5 with as the grade of concrete mix increased

bull The concrete with crushed sand performed better than concrete with natural sand as the grade of concrete mix increased

bull The flexural strength of concrete with crushed sand was marginally increased on the strength of concrete with natural sand

bull The permeability of concrete decreased as the grade of concrete mix increased The concrete with crushed sand was found to be stronger and durable The crushed sand may be used as a substitute to natural sand

References 1 Ahmed A E and EI Kourd A A 1989 Properties of concrete incorporating natural sand and

crushed stone very fine sand American Concrete Journal 86(4)417-424 2 Celik T and Marar K 1996 Effect of crushed stone dust on some properties of concrete Cement

and Concrete Research 26(7) 1121-1130 3 Indian Standard code of practice for Recommended Guidelines for concrete mix-design I S

10262-1982 Bureau of Indian Standards New Delhi 4 Indian Standard code of practice for Methods of Test for Strength of Concrete I S 516-1959

Bureau of Indian Standards New Delhi 5 Indian Standard code of practice for plain and reinforced concrete I S 456-2000 Bureau of

Indian Standards New Delhi 6 Kim J K Lee C S Park C K and Eo S H 1997 The fracture characteristics of crushed lime

stone sand concrete Cement and Concrete Research 27( 11) 1719-1729

184

33 Permeability The permeability of concrete is related to durability of concrete in terms of its resistance against

progressive determination under exposure to sever climatic conditions and leaching due to prolonged seepage of water The permeability is measured in terms of coefficient of permeability by permeability test apparatus in accordance with Indian Standards [5] To find coefficient of permeability of hardened concrete a cube specimen of size 150 x 150 x 150 mm for each of eight mixes were casted The specimens were subjected to a known hydraulic pressure from one side in a permeability test apparatus after 28 days of curing Measuring the quantity of water percolated through it in 100 hours the coefficient of permeability were calculated and reported in Table 4

60

_ 50

0 ~ 40 c en c 30 agt (f)

ci 20 E 0

bull bull 1

-+-7 Day-N 7 Day- C

u 10

1-- 28 Day-N 1 --- 28 Day-C I

0 M15 M20 M35 M40

Grade of Concrete

4 Discussions 1 There was significant increase in compressive strength of concrete with crushed sand (refer Table 4

and Fig 1) 2 The compressive strength was increased by 1944 to 4038 at 7 -day age and increased by 833

to 259 at 28-day age as the grade of concrete mixes were increased (refer Table 5) 3 There was significant gain in compressive strength at early age (Fig 1)

4 The concrete mixes with crushed sand experienced marginal increase in the flexural strength (refer Table noA)

5 The flexural strength was increased by 141 to 348 at 7 day age and increased by 095 555 at 28 day age as the grade of concrete mix increased (refer Table no 5)

6 The coefficient of permeability of concrete was gradually decreased from 176 x 108 ms to 119 x10-8

ms as the grade of concrete mix increased (refer Table no 4 and fig 2)

5 Conclusions

183

An experimental study was performed to examine the strength and durability of concrete with crushed sand as replacement to the natural sand The data assembled during the course of investigation lead to the following conclusions bull The performance of concrete with crushed sand was excellent There was an increase in

compressive strength about 8 to 26 and flexural strength about 1 to 5 with as the grade of concrete mix increased

bull The concrete with crushed sand performed better than concrete with natural sand as the grade of concrete mix increased

bull The flexural strength of concrete with crushed sand was marginally increased on the strength of concrete with natural sand

bull The permeability of concrete decreased as the grade of concrete mix increased The concrete with crushed sand was found to be stronger and durable The crushed sand may be used as a substitute to natural sand

References 1 Ahmed A E and EI Kourd A A 1989 Properties of concrete incorporating natural sand and

crushed stone very fine sand American Concrete Journal 86(4)417-424 2 Celik T and Marar K 1996 Effect of crushed stone dust on some properties of concrete Cement

and Concrete Research 26(7) 1121-1130 3 Indian Standard code of practice for Recommended Guidelines for concrete mix-design I S

10262-1982 Bureau of Indian Standards New Delhi 4 Indian Standard code of practice for Methods of Test for Strength of Concrete I S 516-1959

Bureau of Indian Standards New Delhi 5 Indian Standard code of practice for plain and reinforced concrete I S 456-2000 Bureau of

Indian Standards New Delhi 6 Kim J K Lee C S Park C K and Eo S H 1997 The fracture characteristics of crushed lime

stone sand concrete Cement and Concrete Research 27( 11) 1719-1729

184

An experimental study was performed to examine the strength and durability of concrete with crushed sand as replacement to the natural sand The data assembled during the course of investigation lead to the following conclusions bull The performance of concrete with crushed sand was excellent There was an increase in

compressive strength about 8 to 26 and flexural strength about 1 to 5 with as the grade of concrete mix increased

bull The concrete with crushed sand performed better than concrete with natural sand as the grade of concrete mix increased

bull The flexural strength of concrete with crushed sand was marginally increased on the strength of concrete with natural sand

bull The permeability of concrete decreased as the grade of concrete mix increased The concrete with crushed sand was found to be stronger and durable The crushed sand may be used as a substitute to natural sand

References 1 Ahmed A E and EI Kourd A A 1989 Properties of concrete incorporating natural sand and

crushed stone very fine sand American Concrete Journal 86(4)417-424 2 Celik T and Marar K 1996 Effect of crushed stone dust on some properties of concrete Cement

and Concrete Research 26(7) 1121-1130 3 Indian Standard code of practice for Recommended Guidelines for concrete mix-design I S

10262-1982 Bureau of Indian Standards New Delhi 4 Indian Standard code of practice for Methods of Test for Strength of Concrete I S 516-1959

Bureau of Indian Standards New Delhi 5 Indian Standard code of practice for plain and reinforced concrete I S 456-2000 Bureau of

Indian Standards New Delhi 6 Kim J K Lee C S Park C K and Eo S H 1997 The fracture characteristics of crushed lime

stone sand concrete Cement and Concrete Research 27( 11) 1719-1729

184