The impact of VMA on the rheology, thixotropy and robustness of self-compacting mortars

Abstract

Due to the higher sensitivity of fresh self-compacting concrete (SCC) to small variations in the mix proportions - also referred to as a lower robustness - applications with SCC are still limited. Because viscosity modifying admixtures (VMAs) are often reported to increase the robustness of SCC, the relationship between robustness, rheological characteristics, and thixotropic build-up of selfcompacting mortars is examined whit an experimental program. The robustness with regard to small variations in the water dosage is measured together with the rheological and thixotropic properties of mortars made with various admixtures (purified attapulgite clay, diutan gum, corn starch, and propylene carbonate). Based on those results, the possible connections between the rheology, thixotropy and robustness of self-compacting mortar were evaluated.