Investigation of rheological and mechanical properties of two-component and three-component mortars containing microsilica and slag

With the use of pozzolans and additives, today, a huge change has been made in mortar technology to achieve high strength and durability. The purpose of this study is to make two-component and three- component mortars and compare their rheological and mechanical properties. In this research, compressive, flexural and tensile strength tests were performed on reference mortar, two-component mortars as well as three-component mortars. Slag utilized in making of research mortars was produced in Ahvaz Steel plant. Compressive strength tests were conducted at 7, 28, 56 and 91 days and flexural and tensile strength tests were performed at 28 and 91 days. In the mentioned resistance tests, cubic specimens with dimensions of 50 mm, prismatic specimens with dimensions of 160 × 40 × 40 mm and standard bow-tie specimens were applied, respectively. The results presented that the replacement of microsilica up to 10% by weight of cement increased the compressive, flexural and tensile strengths of two-component mortars, which were significant at all ages compared to the sample without microsilica. With increasing cement substitute microsilica up to 15%, changes in compressive, flexural and tensile strengths follow an inverse nonlinear behavior. Optimal microsilica and slag replacement percentages of 5% and 10%, respectively, increased the three strengths in the three-component mortars, which are significant at all ages compared to the reference sample. With increasing the percentage of replaced microsilica, the flowability of the mortars decreased and with increasing the percentage of slag, the flow increased.