Abstract: Geopolymer concrete was prepared with metakaolin and alkali-activator. The compressive strength and frost resis-tance of geopolymer concrete with a dosage of steel slag, slag or fly ash of 15% was studied and the vacuum volume aspiration ratio of geopolymer concrete was tested. XRD, SEM and DSC-TG analyses were used to investigate the effect of mineral admixtures incorporation on the microstructures and hydration products of geopolymer. The results showed that the compressive strength of geopolymer concrete is effectively improved by steel slag or slag, but the fly ash could make it slightly decrease. The poor resistance of frost can be attributed to the pores and microcracks exist on the surface of geopolymer. The adding of steel slag or slag forms the hydration products such as C-S-H, C-A-S-H gel which fill in the pores can delay its rate of destruction induced by the cycle of freezing and thawing and improve the frost resistance of geopolymer, it maintains relative strength in 90% after 5 freeze-thaw cycles. The fly ash reduces the water consumption to prepare concrete and the unhydrated fly ash particles embedded in the structure contributes to the improvement of density and frost resistance, as the geopolymer concrete maintained 86.9% strength after 5 freeze-thaw cycle, and 79.7% for the control group.
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2018, Vol. 32 
