Effect of Aluminosilicate Nanoparticles on Cement Blends Containing Volcanic Ash and Metakaolin

The scope of this work is designated to make use of multiple micro- and nano-additives to examine their effect collectively on fresh and hardened state of cement. Two sizes of volcanic ash, VA (6 and 17 μm), were incorporated alternatively at a constant ratio of 5%, whereas aluminosilicate was introduced via metakaolin and synthetic aluminosilicate nanoparticles. The incorporation of metakaolin and aluminosilicate nanocomposites serves for the purpose of varying the ratio of micro- to nano-aluminosilicates. Aluminosilicate composites were tailored via sol–gel method by using aramid polymer as a support, with varying precursor ratio to acquire three compositions with Si:Al ratios of 3:7, 5:5, and 7:3. BET analysis revealed that higher pore volume and surface area were associated with higher Si:Al ratio. Raman spectroscopy provided an insight into the pozzolanic rate of cement hydration as influenced by the composition of aluminosilicate nanoparticles. Micro- and nano-aluminosilicates displayed higher uniformity in pore structure as revealed by BET microstructural analysis. Nanoindentation results showed higher modulus and hardness values due to the reduction in the particle size of the volcanic ash. The combination of pozzolanic volcanic ash additives (6 μm VA) and aluminosilicate nanoparticles helped in the involvement of Portlandite to form additional calcium-aluminum-silicate-hydrate (C-A-S-H) phase leading to enhanced strength development.