The present paper establishes that the ratio between the XRD pulse counts of cement clinkers at d=0.278 and 0.274 nm bears a distinct relationship with the degree of sintering of the clinker, which is one of the factors that determine the cement quality. The paper also presents a rapid and accurate method for predicting both 3- and 28-day compressive strength (CCS) of cement mortar cubes based on XRD of the cement clinkers. The method is based on an index Xn derived from the XRD pulse counts at d=0.2959 and 0.287 nm corresponding to alite (hkl=202) and belite (hkl=102) phases of the clinker, respectively. The regression equation derived for a particular plant is (1) 3 day CCS=Xn×240 kg/cm2, when Xn<1 and 240+26 (Xn−1) kg/cm2, when Xn>1, where Xnmaximum=5.5. (2) 28 day CCS=C+C×In/100, where C=3 days CCS estimated by XRD (1), In=90−10Xn, where Xnmax=5.5. Calculated CCS values, in average, vary from the conventional test values by +5.9% to −5.4% and +3.8% to −3.5% in cases of 3- and 28-day CCS, respectively.
