Effect of Curing Temperature on the Mechanical Behaviour of Geopolymer Concrete Prepared Using Locally Available Fly Ash

Abstract: Geopolymer Concrete (GPC) is an innovative, eco-friendly concrete in which cement is replaced by alumina-silicate rich material like fly ash, and chemically activated by alkali solutions. Since GPC is relatively new, extensive studies are still needed to explore this type of concrete as a construction material. This paper presents the study of the effect of curing temperature on the mechanical behaviour of GPC which was produced using locally available fly ash. Concrete cubes of 100 mm x100 mm x100 mm and cylinders of 100 mm diameter and 200 mm in height were cast and all the specimens were cured for 48 hours at four different temperatures including the ambient temperature, 40 °C, 60 °C and 80 °C after 1 day of rest period. Compressive strength (7 day, 28 day), split tensile strength (7 day) and dynamic modulus (28 day) were measured to analyse the behaviour of GPC with the curing temperature. Microstructure of GPC specimens cured at different temperatures was observed through Scanning Electron Microscope (SEM). Test results showed that the compressive strength, split tensile strength and dynamic modulus of GPC have achieved the highest values at the optimum curing temperature of 60 °C. It proves that the oven curing has a significant effect on strength gaining and no strength gain after the optimum curing temperature. Also, the results of GPC properties at the ambient temperature indicate fairly high values.

Key words: Geopolymer concrete, fly ash, curing temperature, compressive strength, split tensile strength.

1. INTRODUCTION

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2. MATERIALS AND METHODOLOGY

2.1. Materials and mix proportions

Table 1 XRF analysis of fly ash

Chemical properties Percentage / (%)

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Table 2 Mix proportions per m3 of concrete

Material Amount/ (kg/m3)

2.2. Casting and curing

2.3. Sample testing

Figure 1 Compressive Strength Test of Cubes

Figure 2 Split Tensile Strength Test

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3. RESULTS AND DISCUSSION

3.1. Effect of curing temperature on compressive strength

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Figure 3 Variation of Compressive Strength of GPC with Curing Temperature

3.2. Effect of curing temperature on split tensile strength

Figure 4 Variation of 7 Day Split Tensile Strength of GPC with Curing Temperature

Figure 5 Percentage of 7 Day Split Tensile Strength that of Compressive Strength at Similar Suring Temperatures

3.3. Variation of pulse velocity with curing temperature

Figure 6 Variation of UPV of GPC with Curing Temperature

3.4. Variation of dynamic modulus with curing temperature

Figure 7 Variation of Dynamic Modulus of GPC with the Curing Temperature

3.5. SEM analysis

Figure 8 SEM images of GPC Cured at (a) Ambient Temperature (b) 40 °C (c) 60 °C and (d) 80 °C

4. CONCLUSIONS

5. AKNOWLEDGEMENTS

6. REFERENCES

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