Effect of using Cement Kiln Dust as a nano-material on the strength of cement mortars

Abstract

In this experimental study, the effects of using nano-sized Cement Kiln Dust (CKD) as a partial replacement for Ordinary Portland Cement (OPC) on the strength of cement mortars is investigated. The CKD was milled up to 4 hours in a planetary ball mill. In addition to the control cement mortar mixture with 0% CKD, a total of 28 concrete mortar mixtures were prepared with four different replacement percentages of nano-CKD (5, 10, 15, and 20 %), and seven different milling times (1, 1.5, 2, 2.5, 3, 3.5, and 4 hours). The compressive strengths of all cement mortar mixtures were evaluated after curing periods of 7, 28, and 56 days. In addition, the chemical, physical and microscopical properties of the nano-CKD were evaluated using Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and X-ray diffraction (XRD). The experimental results showed that the partial replacement of the OPC with the nano-CKD enhanced the compressive strength of the cement mortar by about 15-30% compared with normal mortar without CKD. Moreover, the experimental results indicated that no change was observed in the chemical composition of CKD after 4 hours of milling. However, there was a decrease in the Portlandite content in parallel with an increase in the density and the surface area.