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International Journal of Modern Trends in Engineering and Research

www.ijmter.com e-ISSN No.:2349-9745, Date: 28-30 April, 2016

@IJMTER-2016, All rights Reserved

Effect of Addition of Ordinary Portland Cement on Geopolymer Concrete with Ambient Curing

B. H. Shinde1, Dr. K. N. Kadam2 1 Department of Civil Engineering, G. H. Raisoni College of Engineering, Amravati. India,

[email protected] 2Department of Applied Mechanics, Government College of Engineering, Amravati, India,

[email protected] ______________________________________________________________________________

Abstract- This paper presents the effect of addition of ordinary Portland cement (OPC) in geopolymer concrete for obtaining the higher strength in ambient curing. This paper evaluates the workability and strength properties of geopolymer concrete with Ordinary Portland cement (OPC). In this study the Ordinary Portland cement has been added in mix 0%, 3%, 6%, 9%, and 12% of the total binder with solution to fly ash ratio 0.4 and sodium silicate to sodium hydroxide ratio 2. The result shows that, the Geopolymer concrete with OPC can set at the same rate as that of cement concrete. The samples are cured at room temperature and its fresh and hardened properties are compared with samples which were cured at elevated temperature. The strength increased when increasing the percentage of OPC in the mix. Geopolymer concrete with OPC, the strength increased at 28 days by 94.25% respectively as compared to Geopolymer concrete with ambient curing. In ambient curing the Geopolymer concrete with OPC gives bettor result as compared to plane geopolymer concrete with ambient curing. Keywords- Ambient curing, Ordinary Portland Cement, Compressive Strength

I. INTRODUCTION

India is the second country in the world which produces huge amount of cement. For cement production large amount of energy is required. In India, coal is the prime source of energy. The cement industry is third largest consumer of coal in country. Coal is the main fuel use in the industry as compared to oil and gas. Due to high cost and inadequate availability oil and gas are less use. Approximately 500gm coal is required for production of 1kg of cement. As per the global cement report currently in 2014-15, India produces 390 million tons of cement. In other hand, the total electricity consumed in the country, approximately 80 % electricity is produced from coal. Coal demand is expected to reach 1273MT by 2021-22 (Central Electricity Authority 2014-15). The fly ash generation in India through thermal power plants in 2014-15 was about 185 million tons and utilization was 55.69% (Central Electricity Generation Report). Due to highly presence of silica and aluminium, the fly ash has great potential as a cement replacement material in concrete. For totally replacement of Portland cement, the fly ash needs to activate by highly alkaline solution [1]. Davidovits suggested that, the any powder materials which are rich in silica and aluminiun that can be used as source materials. Such source materials can be activating by using highly alkaline solution that is call Geopolymer. Highly alkaline solution is used to induce the silicon and aluminium atoms in the source materials to dissolve and form the geopolymer paste [2]. The reaction between source

International Journal of Modern Trends in Engineering and Research (IJMTER) Volume 3, Issue 4, [April 2016] Special Issue of ICRTET’2016

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material and alkaline solution is polymerization. For better bonding in polymer, the elevated temperature is required. There are more factors influencing on the strength of geopolymer paste. Literature shows the various guidelines for manufacturing of gropolymer concrete as per their own results which were obtained on the basis of their respective materials. Which are not similar at all the places, such as physical and chemical properties of fly ash, concentration of alkaline solution etc. In India most of the concrete structures are constructed in-situ instead of pre-cast constructions. Practically it is not possible to provide the temperature curing to structure. To achieve the maximum strength of geopolymer at room temperature, there is a need to add such pozzolanic materials which enhance the polymerization reaction and form stronger inorganic polymer bond. The properties of geopolymer with various sources materials, various concentrations of alkaline solution with various ranges of temperature curing has been studied. A dense research is going on to achieve the maximum strength of geopolymer concrete without external temperature curing. Because if Geopolymer concrete with ambient curing achieves the same strength as of geopolymer with temperature curing, the production of Portland cement will reduce and utilization of fly ash will rapidly increase. Ultimately CO2 emission in atmosphere due to production of Portland cement will reduce and problem of disposal of fly ash will be solved. Considering this challenge in view the present research work is carried out.

II. EXPERIMENTAL PROGRAM

2.1 Materials and Mix Details Current research is planned to study the effect of addition of OPC as a replacement of fly ash in geopolymer concrete with ambient curing. Fly ash is replaced by OPC by 3%, 6%, 9% and 12% respectively. For this research work the solution to fly ash ratio is 0.4 and sodium silicate to sodium hydroxide ratio is 2. Rest period is one day and curing temperature and duration is 80oC and 24 hours respectively. These parameters are selected from past research of present author. Unprocessed fly ash obtained from Sofiya coal based thermal power plant, Amravati is used as a source material. The percentage of passing of fly ash from 45μm IS sieve is reported as 90 %. Table 1 shows chemical composition of fly ash. For fast setting and gaining the strength of Geopolymer concrete at room temperature the Ordinary Portland cement (OPC) is used. Locally available river sand is used as fine aggregate and crushed basalt stones of nominal maximum size of 20 mm are used as coarse aggregate. The properties of aggregates are given in Table 2.

Table No. 1 Chemical Composition of Unprocessed Fly Ash Chemical Composition SiO2 Al2O3 Fe2O3 CaO Na2O K2O TiO2 MgO P2O5 SO3 LOI*

Percentage (%) 62.85 27.36 5.18 1.47 0.08 0.63 1.84 1 0.54 0.05 1

*Loss of Ignition

Table No. 2 Physical Properties of Fine and Coarse Aggregate Sr. No. Physical Properties Fine Aggregate Coarse Aggregate

01 Type River sand Crushed Angular

02 Maximum Size 4.75 mm 20 mm

03 Specific gravity 2.52 2.63



04 Water absorption 1.23 % 0.52%

05 Moisture content Nil Nil

2.2 Alkaline Activator Solution To activate the binding property of fly ash, sodium based hydroxide and silicate are used as an activator solution. Locally available industrial grade flake form Sodium hydroxide is used. For making one liter Solution of 14 molar concentrations, 560 gm flake form sodium hydroxide is dissolved in laboratory tab water. Alkaline grade Sodium silicates of 47.4 % total solids are used with sodium hydroxide solution as an alkaline solution. This solution of hydroxide and silicates are mixed together just before adding in the dry mixture. Before mixing this solution in the mix, enough stirring is done using two jars. 2.3 Geopolymer Concrete Mix Details

Mix proportions are decided from the literature. Activator Solution to fly ash ratio is 0.4, whereas

sodium silicate to sodium hydroxide ratio is 2 [6, 8]. Quantity of water is added in the mix by considering the water content in the activator solution. The percentage of fine aggregate is 35% of total aggregate. In this research total 10 mixes are studied. To obtain the maximum strength at room temperature (ambient Curing) the OPC are added separately. The entire ingredient is kept constant and only fly ash is replaced by Ordinary Portland cement (OPC) by 3%, 6%, 9% and 12 % respectively [7]. First mix is prepared for plane Geopolmer concrete with ambient curing (GPA). The second mix is prepared for plane Geopolymer concrete with temperature curing (GPT). The mix 3rd, 4th, 5th, and 6th are prepared for geopolymer concrete with OPC (GPO) of 3%, 6%, 9% and 12% respectively. In mixes 3rd to 6th the fly ash is replaced by OPC. All the mixes are prepared by hand mixing. The mixing procedure is similar as that of cement concrete. After mixing, the slump cone test is conducted for measuring the workability of geopolymer concrete. All cubes are filled in three layers. Each layer is compacted by tamping rod and then kept on vibrating table for 10 to 12 seconds to remove the air voids in concrete cubes. The cubes of 100 mm x 100 mm x 100 mm are used for compression test which are tested at 7, 14 and 28 days after casting. After the casting the cubes of mix one are kept at room temperature for curing up to the day of testing. The room temperature range is 15oC to 32oC. The cubes of mix second are kept for temperature curing of 80oC for 24 hrs. The rest period is one day for cubes of mix second. After the 24 hrs temperature curing, off the oven and cubes are kept as it is in the oven for next 2 hrs for avoiding the drastic change of temperature. Then the cubes are taken out from the oven and kept at room temperature up to the day of testing. The cubes of mixes 3rd to 6th were kept in room for ambient curing. Total 54 cubes are prepared to study the effect of addition of OPC in geopolymer concrete with ambient curing. The details of mix proportion are given in Table 3 for unit volume. In mixes 3rd, 4th, 5th and 6th, the fly ash is replaced by OPC by 3%, 6%, 9% and 12 % respectively. The quantity of other ingredients is kept as it is while replacing fly ash by OPC. The workability of all mixes is measured and present in Table 4.



Table No. 3 Quantity of Ingredients for Unit Volume of Mix (One Cum)

Fly Ash (kg)

Sodium Silicates

(kg)

Sodium Hydroxide (kg)

Fine Aggregate

(kg)

Coarse Aggregate (kg)

Water (kg)

400 107 53 671 1248 57

Fig. 1 Details of Mixing, Slump Cone Test of Workability, Casting and Testing of GPC

Table No. 4 Workability of GPA and GPO (Slump Value)

Mix Details Slump Value (mm)

GPCA 150

GPCO-3% 152

GPCO-6% 145

GPCO-9% 142

GPCO-12% 141

GPCT 150

III. RESULTS AND DISCUSSION

Test for Compressive strength is evaluated at the age of 7, 14 and 28 days after casting as per IS. 516-1975. For each parameter three cubes are tested for compressive strength and average of these three cubes is considered as strength of concrete for that respective parameters. The compression test is conducted on compression testing machine of capacity 3000 kN. The compressive strength of GPA, GPT, and GPO are presented in Table 5. The percentage strength increased at 28 days in mix GPT and GPO as compared to mix GPA are also presented in Table 5. The graphical variation of compressive strength at 7, 14 and 28 days of GPA, GPT, and GPCO are presented in Fig.2. The graphical variation of compressive strength of GPO with respect to day is polynomial. At the time of mixing of ingredients of geopolymer concrete, the sodium hydroxide and sodium silicate are mixed together by using two jars. While mixing both solutions, the temperature of solution is increased up to 50 to 60oC. In case of geopolymer concrete with OPC, the results of workability of all mixes were similar to plane geopolymer concrete (i.e. GPA). After 24 hrs of casting it is observed that the cubes of mix GPA were wet (Not set) and cubes of GPO were set



better. It is observed that the cubes of GPA could not be demold after 24 hrs of casting. The cubes of all other mixes can be demolded after 24 hrs. The cubes of GPO with 3% OPC were brittle as compared to cubes of 6%, 9% and 12% of OPC. The edges of cubes of GPO with 3% are broken while demolding the cubes after 24 hrs of casting. The cubes of GPT are tougher after taking out from oven.

Table No. 5 Compressive strength of Geopolymer Concrete at 7, 14 and 28 Days.

Mix Details

Fly Ash replaced by OPC (%)

Compressive Strength (N/mm2) % Strength Increase w.r.t GPCA at 28

Days At 7 Days At 14 Days At 28 days

GPA 0 4.99 10.48 16.17 ---

GPT 0 39.07 40.03 41.50 156.65

GPO-1 3 11.33 17.63 25.93 60.40

GPO-2 6 11.67 18.65 26.65 64.85

GPO-3 9 13.73 20.33 29.27 81.01

GPO-4 12 14.45 22.61 31.41 94.25

Fig. 2 Variation of Compressive Strength of GPA, GPT, GPO with Respect to Days.

The compressive strength of mix GPA is observed to be lowest as compared to all other mixes at 7, 14 and 28 days. In all mixes the rate of gaining of strength was higher in first 14 days as compared to after 14 days. In mix of GPT the rate of increase of strength from 7 days to 28 days was constant. From these results it found that, the increase the percentage of OPC the strength also increased. The strength of mixes GPO obtained is more than of GPA at 7, 14 and 28 days but less than the mix GPT.

y = -0.025x2 + 1.703x + 3.782R² = 1

y = -0.014x2 + 1.245x + 5.72R² = 1

y = -0.020x2 + 1.423x + 2.700R² = 1

y = -0.014x2 + 1.204x + 3.61R² = 1

y = -0.018x2 + 1.161x - 2.262R² = 1

y = -0.001x2 + 0.170x + 37.95R² = 1

0

5

10

15

20

25

30

35

40

45

0 7 14 21 28

Com

p. S

tren

gth

(N/m

m2)

Days

12% OPC

9% OPC

6% OPC

3% OPC

0% GPA

0%-GPT



In ambient curing, the highest strength is achieved when 12 % OPC has been added in the mix. When mixes with 12 % OPC are tested for the strength at 28 days then the strength is increase by and 94.25% respectively as compared to strength of GPA. From this research work it is observed that the results of Geopolymer concrete with OPC gives bettor strength as compared to plane geopolymer concrete with ambient curing.

IV. CONCLUSIONS

This paper represents the properties of fly ash based geopolymer concrete with ordinary Portland cement. Based on this experimental work the following conclusions are drawn;

Geopolymer concrete with OPC is producing the same workability as that of plane

geopolymer concrete. The mix of Geopolymer concrete with OPC 3%, 6%, 9% and 12%, the strength increased at

28 days by 60.40%, 64.85%, 81.01% and 94.25% respectively, as compared to Geopolymer concrete with ambient curing.

Geopolymer concrete with temperature curing gives highest strength, ie 156.65 % more than geopolymer concrete with ambient curing.

Geopolymer concrete with OPC gives bettor compressive strength as compared to GPA.

The study presented has suggested a good alternative to temperature curing which is relatively difficult in site construction. The study will give valuable inputs to research in ambient curing of geopolymer concrete.

REFERENCES

1. Djwantoro Hardjito, Steenie E Wallah, Dody MJ Sumajouw and B Vijaya Rangan, “Fly Ash-Based Geopolymer

Concrete” Australian Journal of Structural Engineering, Vol. 6, No. 1, January 2005, pp. 1-10. 2. Djwantoro Hardjito, Steenie E Wallah, Dody MJ Sumajouw and B Vijaya Rangan, “On the Development of Fly

Ash-Based Geopolymer Concrete” ACI Materials Journal, November-December 2004, pp. 467-472. 3. Subhash V. Patankar, Sanjay S. Jamkar , Yuwaraj M. Ghugal, Effect of Water-to-Geopolymer Binder Ratio on the

Production of Fly ash Based Geopolymer Concrete, Procedding of the International Conference on Recent Trends in engineering & Technology; 2013 876-881, Chandwad, India.

4. B.V. Rangan, Djwantoro Hardjito, Steenie E Wallah, Dody MJ Sumajouw, “Properties and Applications of Fly Ash-Based Concrete” Material Forum Volume 30- 2006, pp. 170-175.

5. Palomo, M.W. Grutzeck, M.T. Blanco, “Alkali-activated Fly ashes A cement for the future” Journal of Cement and Concrete Research, Vol. 29(1999), pp. 1323-1329.

6. B.H. Shinde, Dr. K. N. Kadam, Properties of Fly ash Based Geopolymer Mortar, International Journal of Engineering Research and Technology, 201, 04 (07), 971-974.

7. B.H. Shinde, Dr. K. N. Kadam, Properties of Fly Ash Based Geopolymer Mortar with Ambient Curing, Proceeding of the 2nd National Conference of Innovations in Civil Engineering; 2016, 203-206, Karad, India.

8. Subhash V. Patankar, Sanjay S. Jamkar , Yuwaraj M. Ghugal, Mix Design of Fly Ash Geopolyme Concrtete; Advances in Structural Engineering, Springer India 2015,1619-1634.

9. M.I. Abdul Aleeem, P.D. Arumairaj, “Optimum mix for geopolymer concrete” Indian Journal of Science and Technology, Vol. 5, No. 3, March 2012, pp. 2299-2301.

10. E. Ivan Diaz-Loya, Erez N. Allouche and Saiprasad Vaidya, “Mechanical Properties of Fly-Ash-Based Geopolymer Concrete” ACI Materials Journal, May-June 2011, pp. 300-306.

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