Influence of pore structure on the properties of green concrete derived from natural pozzolan and nanosilica

Abstract

The strength, pore structure, morphology and mineralogical composition of hydration products of natural pozzolan (NP) and nanosilica (nSiO2) based alkali activated binder (AAB) were examined. It was noted that AAB without nSiO2 was relatively porous with the presence of micro-, meso- and macro-level pores. In contrast, as the proportion of nSiO2 increased in the mixture, the pore structure started to refine with a reduction in the pore volume due to transformation of source material to polymeric compound, such as C-A-S-H with a higher Al absorption in the binder structure. The incorporation of 5% and 7.5% nSiO2 resulted in the refinement of the pore structure due to enhanced polycondensation. Consequently, there was considerable improvement in the mechanical properties. The experimental data indicated that the pore structure evaluation through NMR has served as a tool to understand the relation between the micro- and macro-level performance of the developed AAC.