الملخص الإنجليزي
This research was undertaken to study the effect of the milled or nano-sized cement kiln dust (CKD) addition on the properties of cement mortars and to characterize their physical, chemical, and microscopical features at the nano-scale. In addition to the control mixture, which consisted from bulk sized CKD (unmilled material), 28 mixtures were prepared using different proportions of CKD at 5, 10, 15, and 20%, replacement by total weight of ordinary Portland cement for different milling times of 1, 1.5, 2, 2.5, 3, 3.5, and 4 hours and under different curing periods of 7, 28, and 56 days. The influence of nano-CKD particles on the properties of hardened cement mortars were evaluated through the measurement of compressive strength and from the characterization of their microstructure using scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). Overall results indicated that the compressive strengths increased by 15 to 30 % for almost all mixtures incorporating nano-CKD compared to the strength results obtained for the original control mixture. Moreover, it was observed that the initial setting time of fresh cement pastes were reduced after adding nano-CKD particles. SEM results indicated that the interface pores between cement and sand particles were filled and bonded with the addition of nano-CKD. In addition, results also showed that nano-CKD produced denser cement mortars by enhancing their mechanical strengths, especially after 28 days of curing.
