Production of High-performance Concrete by Addition of Fly Ash Microsphere and Condensed Silica Fume

With reference to the packing model of concrete materials, addition of fly ash microspheres (FAM) to fill the voids between cement grains, followed by addition of condensed silica fume (CSF) to further fill the voids between FAM would reduce the water content to achieve the desired flowability. This could allow the adoption of lower water/cementitious materials (W/CM) ratio to produce High-Performance Concrete (HPC). This study was aimed to evaluate the effects of FAM and CSF on the packing density of cementitious materials and the flowability and strength of cement paste. The results showed that the addition of FAM and CSF can significantly increase the packing density, thereby enhancing flowability and strength performance concurrently.