Influence of raw materials and oxide composition on the properties of geopolymer mortar
10 groups of geopolymer mortars were prepared by changing the combination and proportion of metakaolin,ground granulated blast furnace slag(GGBFS)and fly ash.The setting time,flowability,compressive strength and flexural strength of geopolymer mortars were tested.The influence of the mixing ratio of raw materials on the properties of geopolymer mortars was investigated,and the effect of oxide composition on the mechanical properties of geopolymer mortars was analyzed.The results showed that adding GGBFS or metakaolin significantly weakened the flowability of fresh geopolymer mortars.The setting time of geopolymer mortars decreased significantly with the increase of the content of GGBFS,and was basically not affected by the content of metakaolin.The compressive strength and flexural strength of the geopolymer mortars containing three mineral admixtures were higher than those of the geopolymer mortars containing single or two mineral admixtures.The ternary geopolymer mortar containing 30%metakaolin,30%GGBFS and 40%fly ash had the highest 28 d compressive strength(123.6 MPa)and flexural strength(10.4 MPa),which has the potential to prepare ultra-high performance concrete.When the range of SiO2/Al2O3 ratio was from 0.72 to 0.79 and the range of CaO/SiO2 ratio was from 0.4 to 0.5,the geopolymer mortar was not less than compressive strength of 97.8 MPa,and their highest strength reached 121.2MPa.
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