Comparative Study Involving Effect of Curing Regime on Elastic Modulus of Geopolymer Concrete

Peiman Azarsa,Rishi Gupta

doi:10.3390/buildings10060101

Abstract

Geopolymer Concrete (GPC) as a cement-less construction material has attracted worldwide attention due to its lower carbon footprint. There are numerous studies reported on GPC made using different by-products including fly-ash. However, since the use of bottom-ash is comparatively limited, making potassium-based GPC using this waste can be an alternative to Portland Cement Concrete (PCC). In this study, two methods of accelerated curing were used to determine the influence of elevated temperature on the compressive strength of GPC, composed of 50% bottom-ash and 50% fly-ash. GPC specimens were cured using various temperatures including ambient, 30 °C, 45 °C, 60 °C, and 80 °C for 24 h, all followed by 28 days of ambient curing. The highest compressive strength was obtained with steam curing at a temperature of 80 °C for a duration of 24 h. It is of great significance to evaluate elastic modulus of the concrete mixture so that the short-term rigidity of structures subjected to elongation, bending, or compression can be predicted. In this study, a longitudinal Resonant Frequency Test (RFT) as a non-destructive test (NDT) was used to calculate the elastic modulus of both GPC and a comparative PCC mix. Based on the results, PCC had higher resonant frequency (by about 1000 Hz) compared to GPC. A review of empirical models for predicting GPC’s elastic modulus showed that all of the predicted elastic modulus values were lower than experimental values.

Highlights

One of the main environmental issues associated with the production of cement is Green HouseGas (GHG) emissions to the atmosphere, as well as the consumption of natural resources
The results showed that the elastic modulus increases as the compressive strength of Geopolymer Concrete (GPC) increases
It is reported that GPC and Portland Cement Concrete (PCC) are considered to be highly workable when GPC and PCC gain a slump value over 90 mm and 180 mm, respectively [65,66]

Summary

Introduction

Gas (GHG) emissions to the atmosphere, as well as the consumption of natural resources. It is estimated that one ton of cement production needs about 1.5 tons of natural resources and emits about one ton of carbon dioxide (CO2 ) into the air [1,2,3]. About 112 million tons of fly-ash as waste material is produced annually in the world [4]. The use of fly-ash in the concrete mixture can produce positive environmental, economic, and product benefits [5]. About 80% of the unburned material or fly-ash is entrained in the flue gas when pulverized coal is burned in a dry condition. In the United States in 2017, 38.2 million tons of fly-ash and

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