Cement (Jun 2022)
The efficacy of portland-limestone cements with supplementary cementitious materials to prevent alkali-silica reaction
Abstract
This paper details a study on the efficacy of portland-limestone cements (PLCs) in combination with supplementary cementitious materials (SCMs) to prevent expansion due to alkali-silica reaction (ASR). The PLCs studied include both interground (10–15% limestone by mass) and interblended (10% limestone by mass) systems. In this study, ASTM Type II/V cements, five different SCMs, two very-highly reactive fine aggregates, and six SCM combinations were investigated. A total of 100 mixtures were assessed using three different accelerated laboratory test methods to investigate if the SCM combinations that are used with OPCs can be utilized as-is, increased, or decreased when used instead with PLCs. The test methods used to evaluate ASR included the Pyrex mortar bar test (PMBT, ASTM C441), the accelerated mortar bar test (AMBT, ASTM C1567), and the miniature concrete prism test (MCPT, AASHTO T 380). The difference in performance between PLCs with SCMs and parent OPCs with SCMs in the MCPT conditions was further evaluated using pore solution alkalinity and electrical resistivity analysis. The efficacy of the SCM combinations to prevent ASR was also evaluated with a pozzolanic reactivity test. The expansion results from the accelerated laboratory test methods revealed that the mixtures with PLCs and SCMs had similar or better overall performance when compared to the mixtures with the parent OPCs and SCMs. It was observed that the particle size of the added limestone in interblended PLC with SCM mixtures could have a significant influence on the ASR expansion that may alter the output of the test (pass/fail). Consequently, the SCM combinations that are used with OPCs can likely be utilized as-is when used with interground PLCs with up to 15% limestone to prevent ASR. The pore solution and bulk electrical resistivity analysis showed that the lower pore solution alkalinity and higher resistance to mass transport are the main contributing factors towards PLCs’ overall improved performance for ASR mitigation in the presence of SCMs.
