Accelerated Laboratory Testing for High Early StrengthConcrete for Alkali Aggregate Reaction

Aggregate makes up a significant portion of concrete. However, unlike cement, there are limited choices as to the composition and source of aggregate to be used. It has been shown in the laboratory and in the field that certain types of aggregate can cause deleterious expansion through a reaction known as alkali-silica reaction (ASR). In order to ensure the durability of new pavements and projects, the susceptibility of aggregates and cements need to be investigated. An accelerated test for ASR susceptibility was used in which mortar bar length changes were measured and used to indicate the potential of being reactive. Aggregate consisting of granite, mylonite, phyllonite, and ultramylonite were tested. These aggregates have the same chemical and mineralogical composition, however they all have differences in grain size. For the samples studies, smaller grain size indicated a higher amount of deformation. Two aggregate types were chosen for which the different types of cements would be tested. The choices were a mildly reactive granite and a highly reactive phyllonite. Five cements from four different manufactures were tested. Each cement was used in two sets of experiments: one containing granitic aggregate and the other containing phyllonitic aggregate. The four cements were Type I/II portland cement (I/II), Type III portland cement (III), two calcium sulfoaluminate cements (CSA I, and CSA II), and a calcium aluminate cement (CA).