Correlating Thixotropy of Self-Consolidating Concrete to Stability, Formwork Pressure, and Multilayer Casting

The use of self-consolidating concrete (SCC) gained wide acceptance in the construction industry. The main objective of this paper is to classify the performance of freshly mixed SCC including stability, formwork pressure, and multilayer casting according to its thixotropic level (A(Thix)); this would facilitate prediction of casting and precasting results at the construction site. Test results showed that low thixotropic mixtures having A(Thix) less than 0.2 Pa/s are not recommended for construction works given the reduced stability associated with high bleeding and sedimentation rates. In contrast, high thixotropic mixtures with A(Thix) larger than 0.75 Pa/s are very stable, and particularly adapted for casting vertical elements given the reduced formwork pressure. Yet those later mixtures are very sensitive to delays or stoppages between successive concrete lifts, resulting in reduced interfacial bond strengths. The moderate thixotropic mixtures having A(Thix) between 0.2 and 0.75 Pa/s showed adequate performance regarding multilayer casting in horizontal elements. (C) 2016 American Society of Civil Engineers.