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.

Keywords:

• natural pozzolan (NP)
• alkali activated concrete (AAC)
• nano silica
• compressive strength
• morphology and mineralogical composition
• pore structure

Disclosure statement

The authors declare that this research work does not have any conflict of interest.

Acknowledgements

The authors gratefully acknowledge the School of Civil Engineering, Universiti Sains Malaysia for providing the needed support for undertaking this research work. The Center for Engineering Research (CER) of the Research Institute, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia is specially acknowledged for providing the necessary support for this work. The authors are also grateful to the Center for Integrative Petroleum Research at KFUPM for providing the support to conduct some of the experiments.