Effects of nano-silica on cement-fly ash modified crushed rocks base materials

Abstract

Cement modification of Crushed Rock Base (CRB) material is required to improve some characteristics such as water susceptibility or stiffness. This kind of soil stabilisation can be more effective if other pozzolanic products can also contribute to the mixture to achieve the desired aims. In this research, both of fly ash and nano-silica material was added to a CRB material to investigate the variation of design parameters and internal microstructures. Fly ash particles are often coarser than nano-silica particles, thus the presence of these produces provide a broad range of particle size distributions of pozzolanic material in cement modified CRB material. The benefit of this idea is generation of less porous material with high strength which is favorable. Thus, different trial batches of this material were subjected to resilient modulus (Mr) and Unconfined Compressive Strength (UCS) to study the changes in design parameters. Furthermore, different techniques of scanning electron microscopy (SEM) imaging methods were utilized to investigate the micro structural changes of hydration products.