Strength and elevated temperature resistance properties of the geopolymer paste produced with ground granulated blast furnace slag and pumice powder

Abstract

The production of cement results in large amounts of CO2 emissions. In order to reduce the energy consumption and gas emissions associated with cement production, a new technology called geopolymerisation has been developed to produce concrete without the use of cement by using aluminosilicate materials as raw materials. The purpose of this study is to evaluate the effect of various parameters on the geopolymer based slag/pumice paste. Slag (GGBFS) and pumice powder were used as binders in different slag/pumice ratios (100:0, 90:10, 80:20, 70:30 and 60:40) and activated with sodium hydroxide (NaOH) at 12 and 14 M concentration and cured for 3 and 7 days at 65 °C temperature. The effect of these parameters on compressive strength and resistance to elevated temperatures was investigated. Microstructural (SEM, EDX) and chemical (FT-IR, XRD) analyses were also carried out to determine the effect of slag/pumice ratio, NaOH concentration and curing time on the properties of the geopolymer pastes. The results showed that the use of slag significantly increased the compressive strength, while the use of pumice with slag increased the resistance of geopolymer pastes to elevated temperatures. For the geopolymer paste produced with slag, high compressive strength can be obtained by a long period of oven curing, whereas for pumice a short period of oven curing and a long period at low temperature can be used. In conclusion, the most effective of the different parameters was the percentage of slag/pumice in the first degree and then the molarities of NaOH, while the least effective parameter was the curing time.

Keywords

• Geopolymer
• Slag
• Pumice
• Compressive strength
• NaOH concentration
• Curing