EVALUATION OF COATING MATERIALS USED TO ENHANCE THE PROPERTIES OF LIGHTWEIGHT AGGREGATE

Two major issues associated with the production of lightweight concrete are high-water absorption and low unit-weight. To minimize the absorption of lightweight aggregate LWA (pumice) with maintaining low unit-weight, pumice particles were treated using different coating materials. The research evaluates the effect of coating materials and technique on enhancing the properties of pumice based on absorbency and unit-weight. The research included 36 samples were prepared and coated in different materials, quantity, layers, and initial moisture content. The samples were coated with either cement paste (CP), CP containing silica fume (SF), or CP containing polymer, and applied in either one or two layers; the samples were either oven-dried or surface-saturated state. The results showed that the treatment of LWA significantly reduces the absorption of pumice. The pumice coated with CP containing SF exhibited the highest reduction in absorption by up to 65% when applied in two layers and by 57% when applied in a single layer under OD conditions. The results also presented that the smaller quantity of coating materials, the greatest effect on the pumice properties. Consequently, pumice coated with 500 gm showed the greatest reduction (9%) in absorption compared to pumice coated with 750 and 1000 gm, especially at OD conditions