Study of the Effect of Cement Setting Delays on Properties of Mortar and Cement Paste

Abstract

Many previous studies have proven that the ash of olive fruit residues delays the setting time of cement, but there is no confirmation of the effectiveness of ash in delaying the setting time compared to industrial retarders that are used as an addition to concrete, hence this research aims to verify the ability of ash residues of olive fruits. Olives on delaying setting time and comparison with industrial retarder, as well as the effect of ash and industrial retarder on the properties of cement mortar. In this study, olive waste ash and liquid industrial retarder were added and mixed in several test samples of the paste and cement mortar with substitution ratios of 0.6% and 1% of the weight of the cement. A reference test sample that did not contain any kind of additives was also mixed for the purpose of comparison. The basic (cement - water - fine aggregate) is stable in all mixtures. Several physical and mechanical tests were conducted to find out the effect of additives on the setting time of the cement paste, as well as the texture of the soft cement mortar and the compressive strength of the hard cement mortar. It was found through the results that with the increase in the substitution ratio from 0.6 to 1%, the initial setting time for the cement paste containing the ash of olive fruit residues increased to 38 minutes, and the initial setting time increased by 5 hours for the industrial inhibitor samples, compared to the initial setting time for the reference sample. The use of ash from olive fruit residues gives a solid texture to the cement mortar, and the flow diameter increases with the increase in the percentage of replacement, while the industrial retarder gives a dry texture and the flow diameter decreases with the increase in the percentage of replacement. The compressive strength of cement mortar containing industrial retarder decreases with the increase in the percentage of replacement, while the compressive strength of cement mortar increases with the increase in the percentage of replacement for olive ash residues.