The effect of styrene acrylate on the mechanical properties of repair mortars and comparison of curing conditions

In order to repair a concrete structure, it is currently necessary to have appropriate recognition of repair materials to achieve an effective and efficient repair. Therefore, the repair materials should be selected in a manner that different properties such as modulus of elasticity and thermal compatibility of the modified mortar be close to the substrate concrete of the structure. Styrene acrylate (SA) is a latex in a cement-based repair mortar, which has a good thermal compatibility with the substrate concrete. So, in this study, five mixtures of repair mortars have been prepared with different ratios of SA to cement materials (0, 5, 10, 15 and 20%) and their physical and mechanical properties including density, consistency and compressive, flexural and tensile strength have been investigated under two curing conditions In the first curing condition, the specimens are immerged in water for 24 hours after demolded and then maintained in the specific temperature and humidity. (Combined curing condition). In the second curing condition, the specimens are immerged in water up to the age of the test. The first curing condition, comparing with the second one, showed the better mechanical properties for the all test ages due to cement hydration at an early age and the formation of the polymeric film. The use of SA increased the flow and reduced the density. Moreover, the use of SA in repair mortar, in polymer to cement material ratio of 20%, reduced the compressive strength by 49% under combined curing condition at 28 days; SA, however, increased the flexural and tensile strength by 21% and 19%, respectively, in the polymer to cement materials ratio of 10% under combined curing condition at 28 days.