Effect of nanosilica and silica fume on the mechanical properties and microstructure of lightweight engineered cementitious composites

Abstract

This paper proposes the use of nanosilica (NS) and silica fume (SF) to improve the mechanical properties of lightweight engineered cementitious composites (LECCs) and compensate for the drawbacks of lightweight fillers. Twelve LECC mixtures were prepared to study the effect of NS and SF on the mechanical properties of LECCs, and the influence mechanism was analyzed by microscopy. The results showed that the incorporation of NS can significantly improve the mechanical properties of LECCs. This improvement in performance derives from the nucleation and pozzolanic effects of NS. The nucleation effect promotes the hydration of cement. The pozzolanic effect consumes more Ca(OH)2 and forms more calcium silicate hydrate (C-S-H). The combined use of NS and SF was more effective in improving the performance. Incorporating SF based on a 3% NS content can consume more Ca(OH)2 and further improve the mechanical properties of LECCs.