No abstract

The changes in hydrated cement composition were measured as a means of quantifying the impact of nano silica size and surface area on cementitious properties. Nano silica dispersions were dosed to have an equal amount of exposed and reactive silica surface area, which contribute to pozzolanic reaction. The amount of calcium hydroxide was measured through thermogravimetric analysis to identify hydrate growth. The chemical shrinkage and compressive strength were also evaluated as a means to understand the impact that nano silica had on the early stages of hydration. Cement composites receiving the higher dosages of the larger nano silica particles exhibited higher levels of enhancement, showing decreased calcium hydroxide, decreased chemical shrinkage and increased compressive strength. The smaller nano silica particles exhibited enhancements at lower dosages, but at higher dosages an increase in calcium hydroxide, an increase in chemical shrinkage, and a decrease in compressive strength was recognized.