Deformation Behaviors of Engineered Cementitious Composites (ECC) modified with Nano-silica (NS)

Abstract

The effects of adding nano-silica (NS) and polyvinyl alcohol fibre (PVA) on drying shrinkage, Poisson's ratio, and elastic modulus of NS-modified self-consolidating engineered cementitious composite (NS-modified SC-ECC) are investigated in this work. The NS-modified self-consolidating ECC mixes were developed using the two variables, that is, NS particles (0%, 1%, 2%, 3% and 4%) and PVA fiber (0.5%, 1%, 1.5%, and 2%). However, to ensure each mix complies with the self-consolidating requirements, a high-range water reducer (HRWR) was utilized to guarantee the self-consolidating qualities of the mixtures. The self-consolidating mixes were used to prepare three samples for each mixture and tested for elastic modulus, shrinkage, and Poisson’s ratio. The results of the experiments revealed that adding 2% of nano-silica particles raised the elasticity modulus for each constant PVA fibre volume. The Shrinkage behaviours improved at 2% NS and 2% PVA percentages. Nano-silica particles further improved the bond between the fibre and matrix by utilising the calcium hydroxide created during cement hydration to start a pozzolanic reaction that generates more calcium-silicate-hydrates (C-S-H) gel. The results of the Poisson’s ratio range between 0.11 – 0.22 for the eight mixed combinations of PVA fibre (0.5%, 1.0%, 1.5%, and 2.0%) and NS (1% and 2%), m5 – m12. Mix m12 had the lowest value of Poisson’s ratio, indicating having the best strength value as the fibre/matrix interface is improved by densification by NS particles and pozzolanic reaction products.