The Impact of Using Fly Ash, Silica Fume and Calcium Carbonate on the Workability and Compressive Strength of Mortar

Abstract

Pozzolanic materials and calcium carbonate can be used to partially replace the use of cement in making mortar or concrete without altering the rheological properties of the fresh mixture. This study focuses on the use of fly ash in the range of 0-30%, silica fume 0-10% and calcium carbonate 0-15% of the cement content, by mass. The workability of the fresh mortar was evaluated and the compressive strength of hardened mortar were measured at the ages of 7, 14, 28 and 56 days. Test results show that increasing partial replacement of cement with fly ash increased the workability and compressive strength of mortar. The use of silica fume reduces the workability of the fresh mortar, and thus requires the addition of superplasticizer to improve the workability. Finer particle size of calcium carbonate also increase workability. The addition of calcium carbonate resulted in higher early strength, whereas the Strength Activity Index (SAI) values slightly reduced with age.