Experimental comparisons between one-part and normal (two-part) alkali-activated slag binders

Abstract

One-part alkali-activated slag (AAS) binders are more promising in large-scale constructions because one-part mixing procedure is safer and easier to handle compared to normal two-part method. Thus, this study aims at investigating different properties of one-part AAS binders and control samples prepared using the two-part method. Experimental results of the former suggested the hardening time was greatly extended, but the workability showed little difference. Besides, compared to the control, one-part AAS binders had similar early compressive strength (within 7 days) and flexural strength in all tested curing stages but lower later compressive strength (from 28 days). The characterisation of the porous structures suggests that there were fewer C-A-S-H gels for one-part binders evidenced by less volume of mesopores but with larger amount of bigger pores. In addition, mineralogical and microstructural analyses imply that there was no hydrotalcite formed in the one-part AAS binders. Moreover, one-part AAS binders are more susceptible to efflorescence, presumably further affecting their surface and long-term durability.