Comparative Analysis of Geopolymer Concrete with Different Proportions of Fly ash and GGBS with Conventional Concrete Considering the Strength and Durability Parameters

Abstract

The global demand of concrete for the construction of infrastructures is continuously increasing. The production of cement is highly intensive and it emits a lot of CO2 into the air which leads to the global warming. One of the effort to produce the environment friendly concrete is geopolymer concrete which emits less CO2. In the present study the feasibility of industrial by-products i.e.; Fly Ash (FA) and Ground Granulated Blast Furnace Slag (GGBS) powder as eco-friendly and sustainable is studied. So the main aim of this study is to analyse the performance of fly ash and GGBS based geopolymer concrete with conventional concrete which are compared with respect to strength and durability parameters for (7days and 28 days) curing period. In this study strength parameters includes compressive strength, split tensile strength and flexural strength and durability parameters includes acid attack test and rapid chloride permeability test. The two different proportions of (70% fly ash+ 30% ggbs) and (60% fly ash+ 40% ggbs) are used in geopolymer concrete. The Alkaline solutions used are sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). The study includes casting of geopolymer concrete and conventional concrete specimens and tested for (7 and 28 days) ages for both strength and durability. The results show that Geopolymer concrete gives good strength and durability compared to conventional concrete. Thus, the Geopolymer concrete can be considered to be an environmentally pollution free construction material.

Introduction

I. INTRODUCTION

Davidovits [1] first introduced the word Geopolymer in 1978 to present the wide scope of material characterisation by series or web of organic molecules. The chemical composition of the geopolymer material is similar to natural zeolitic materials, but the microstructure is amorphous. For the Any material that contains mostly silicon (Si) and aluminium (Al) in amorphous form is a possible source material for the manufacture of geopolymer. To impart a proper unbreakable binding forum this mechanization chiefly depends on the utilisation of industrial waste products or natural materials. Metakaolin, low calcium ASTM Class F fly ash, combination of metakaolin and fly ash, organic Al-Si minerals, combination of calcined and non-calcined minerals, combination of GGBS and metakaolin are investigated as source materials. Geopolymer are hardened material with three dimensional structures similar to aluminosilicate glass structures.

Cement is major ingredient of concrete. The cost of cement is increasing day by day due to its limited availability and large demand. At the same time the global warming is increasing day by day. Manufacturing of cement also releases carbon dioxide. In the present study an attempt been made on concrete and also an experimental investigation on the concrete using by replacing cement with Fly ash and GGBS to decrease the usage of cement as well as emission of concrete Experimental studies were performed on plain cement concrete and replacement of cement with Fly ash and ggbs is done. In this study the concrete mix were prepared by using fly ash, ggbs, sodium silicate, sodium hydroxide.

 A comparative analysis has been carried out for concrete to the Geopolymer concrete in relation to their compressive strength, split tension strength, flexural strength, acid resistance and rcpt test.

The concrete made with fly ash and ggbs performed well in terms of compressive strength, split tension strength, flexural strength, acid attack test and rcpt test showed higher performance at the age of 7,28 days than conventional concrete.

The main aim of this study is –

1. To study the durability and strength parameters in accordance with the geopolymer concrete with varying amounts of ggbs and fly ash and comparing these parameters with conventional concrete.
2. To examine the performance of geopolymer concrete and conventional concrete under effects of and acid exposure condition and determine the resistance to acid exposure condition
3. To identify the potential use of fly ash and ggbs in the geopolymer concrete which will be environment friendly and economical and more effective than conventional concrete.
4. To determine the best proportion of fly ash and GGBS in geopolymer concrete which give approximately equal strength and durability with respect to conventional concrete.

II. MATERIALS USED

1. Sand: Locally available crushed sand is used as fine aggregate. The test carried out on fine aggregates are as follows:

Table 2.1: Test results of fine aggregate-

2. Cement: Locally available ordinary Portland cement (ACC -43 grade) is used for throughout casting of normal concrete specimens

Table 2.2: Test results of OPC-

3. Coarse Aggregate: A crushed ballast rock of 20mm size was used as coarse aggregate. The coarse aggregate is locally available. The following test were carried out on the coarse aggregate samples

Table 2.3: Test results of coarse aggregate-

4. Fly ash: Class-F fly ash was procured from “RMC plant” Kolhapur (Maharashtra) and is used as one of the primary raw materials.

Table 2.4: Chemical composition of fly ash-

5. GGBS: GGBS was procured from “Malsa Factory”, Kupawad (Maharashtra)

Table 2.5: Chemical composition of GGBS-

6. Alkaline Solution: In this investigation, 10 molar concentration of sodium hydroxide solution was selected based on the trial mix results to check for strength characteristics and durability characteristics of Geopolymer mix. For the present study the ratio of NaOH: Na2SiO3 is 2 The NaOH solution should be handled properly with special care and precautions as high exothermic reactions           occur during the process which may affect the human skin and eyes.

7. Hcl , NaCL, NaOH: 1 percent concentrated hydrochloric acid was taken for the acid attack test and Nacl and NaOH was taken for the rapid chloride permeability test. These three solutions were used for the durability analysis.

III. METHODOLOGY

1. Quantity Estimation Of Steel: For project the balanced section of beam of length 900 mm, width 150 mm and depth of 150 mm is selected and top bars are two bars of 10 mm diameter bottom bars are two bars of 10 mm diameter and stirrups are 6 mm in diameter and 120 mm spacing Now, Length of Bar = length of beam – (2 X cover) = 900 - (2 X 30) = 840 mm Therefore, Top bar = 840mm Bottom bar = 840mm Length of stirrup = L = 2a + 2b + 2 (10 X ∅)  = (2X90)+(2X90)+2(10X6) = 480mm No. of stirrups = (length – cover/ c/c distance)+ 1 = (840−30 / 120 )+ 1 =7.75 = 8 no. of stirrup

Table 3.1: Quantity of steel required for one beam-

In the present investigation total 18 nos of beam specimens are required in which 9 specimens are of geopolymer concrete and 9 specimens are of conventional concrete. So quanity of steel required for 18 beams-Top bars = 1.036 X 18 = 18.64 = 19kgs Bottom bars = 1.036 X 18 = 18.64 = 19kgs Stirrups = 0.852 X 18 = 15.336 = 16kgs

2. Mix Design Of Conventional Concrete: For the mix design of conventional concrete IS 10262 and IS 456-2000 guidelines and general procedure is followed in the present investigation

After assuming the stipulation for proportioning the target mean strength, water cement ratio, water content, calculation of cement content, aggregate proportion between course and fine aggregate was found out. After mix calculation for one meter cube volume of concrete is carried out and mix design of conventional concrete (one meter cube) for the present investigation is shown in the table below:

Table 3.2: Mix design of conventional concrete-

3. Mix Design Of Geopolymer Concrete: As there are no code provisions for the mix design of geopolymer concrete from is code therefore the mix design of geopolymer concrete is obtained by trial and error basis method. The density of geopolymer concrete is assumed and rest of calculations are done on the basis of density of concrete, binder content, aggregate binder ratio. By assuming the density of geopolymer concrete the total aggregate content is assumed as 75% of density.

Then the alkaline liquid to fly ash + ggbs ratio is assumed as 0.55 in this investigation. Quantity of binder = 315 kg/m3 The ratio of fly ash: GGBS is 70%:30% i.e., Fly ash = 220.5 kg/m3 GGBS = 94.5 kg/m3 The ratio of fly ash: GGBS is 60%:40% i.e., Fly ash = 189 kg/m3 GGBS = 126 kg/m3 then quantity of alkaline liquid required is found out.The ratio of sodium silicate(Na2SiO3) solution-to-sodium hydroxide(NaOH) solution was adopted as 2. The sodium hydroxide solids (NaOH) is mixed with water to make a solution with a concentration of 10 Molar. Superplasticizer was added to maintain adequate workability.

Table 3.3: Quantity of geopolymer concrete for each specimen-

4. Test Methods: The methodology of casting of geopolymer as well as conventional concrete is same. The coarse, fine aggregates, fly ash and GGBFS were first dry mixed for about 5 minutes and then the solution was added and it was mixed for about 4-5 minutes until it resulted in homogenous concrete mix.

Immediately after mixing, the concrete was tested for its slump cone test and then concrete was poured into the moulds of beam specimens of size 150mm x 150mm x 900 mm, cube specimens of size 150 mm x 150mm x 150 mm, cylindrical specimens of height 300 mm and diameter 150 mm and RCPT test specimens of size 50mm x100mm in diameter in three layers, each layer being tamped 25 times and then vibrated in vibrating machine so that no voids are there. After demoulding Geopolymer specimens were given ambient curing at room temperature and concrete specimens were immersed in water.

5. Final Mix: After getting the results of trial mix the final mix of (70%fly ash +30%ggbs) and (60%fly ash +40%ggbs) are finalised and comparative analysis is carried out at 7and 28 days age of curing with 10 molar alkaline solution

IV. RESULTS AND DISCUSSION

Test conducted in the present investigation for comparative analysis are as follows–

Compressive strength test

Split tensile strength test

Flexural strength test

Acid attack test

Rapid chloride permeability test

1. Compressive Strength Test: Compressive test of concrete has been taken by testing cube of size 150x 150x150mm cube after 7 days and 28 days of normal curing and ambient room temperature curing and the results are recorded-

2. Split Tensile Strength: Split tensile strength test of concrete has been taken by testing cylinder of height 300mm and dimeter 150 mm after 7 and 28 days of normal curing and ambient room temperature curing and the results are recorded-

3. Flexural Strength Test: Flexural strength test of concrete has been taken by testing balanced section of beam of size 900mm x 150mm x 150mm with reinforcement at top and bottom  after 7 days and 28 days of normal curing and ambient room temperature curing and the results are recorded-

4. Acid Attack Test: Acid Exposure Hydrochloric acid (HCL) of 1% concentration was considered to be representative of aggressive sewer environments and 1% Hydrochloric acid (HCL) solution used to investigate the acid resistance. Concrete cube 150 × 150 × 150 mm samples were immersed in 1% Hydrochloric acid solution for 60days and percentage weight loss after acid attack immersion is recorded.

5. Rapid Chloride Permeability Test: Concrete with the thickness 50mm and diameter 90-100mm is used as a test specimen. Charge passed in coulombs through RCPT test specimens are recorded. And it was observed that charge passed in coulombs is approximately equal.

Table 4.5: RCPT test results

V. ACKNOWLEDGMENT

It is a genuine pleasure to express my thanks and gratitude to my guide and mentor Prof S.P.Deshamukh, Department of Civil Engineering, Sanjay Ghodawat University, Kolhapur. His dedication and keen interest above all his overwhelming attitude to help his students had been solely and mainly responsible for completing my work. His timely advice, meticulous scrutiny, scholarly advice and scientific approach have helped me to a very great extent to accomplish this task.

I owe a deep sense of gratitude to our PG coordinator Prof C. S. Patil, Department of Civil Engineering, Sanjay Ghodawat University, Kolhapur for his keen interest at every stage of my research. His prompt inspirations, timely suggestions with kindness, enthusiasm and dynamism have enabled to complete my thesis.

I take my deep sense of gratitude and reverence to Dr. A. D. Katdare, Department of Civil Engineering, Sanjay Ghodawat University, Kolhapur who constantly motivated, supported, encouraged and guided me. I would like to thank him for providing me the requisite opportunities and facilities

Conclusion

The experimental investigation carried out for comparative analysis of geopolymer concrete with different proportions of fly ash and GGBS with conventional concrete and concluded that: 1) At early 7days of curing the compressive strength of geopolymer concrete is more than conventional concrete but after 28 days of curing the compressive strength becomes slightly more than conventional concrete. Compressive strength of geopolymer concrete with 70% fly ash and 30% GGBS gives approximately slightly more value than conventional concrete. 2) As we increase the proportion of GGBS content in geopolymer concrete then it gives high early strength value so the proportion of GGBS content to be provided in geopolymer concrete should be adequate. 3) As we increase the proportion of sodium hydroxide in geopolymer concrete the strength is going to increase. 4) Workability of geopolymer concrete directly depend on aggregate binder ratio. 5) Split tensile strength of conventional concrete and geopolymer concrete are almost gives equal values. 6) Flexural strength of conventional concrete is less than geopolymer concrete. Conventional concrete fails in flexure earlier than geopolymer concrete. Hence geopolymer concrete is more durable than conventional concrete. 7) In exposure of acid attack for 60 days the average weight loss of conventional concrete is more than geopolymer concrete hence it is concluded that the geopolymer concrete has better resistance to acid exposure condition than conventional concrete. 8) From RCPT test it is concluded that the charge passed to concrete specimen is almost equal for conventional as well as geopolymer concrete. 9) Geopolymer concrete with 70% fly ash 30% GGBS is best proportion as a replacement of cement which gives acceptable strength and durability approximately equal to conventional concrete

References

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Copyright

Copyright © 2022 Vrushabh V. Patil, S. P. Deshamukh. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.