Technical Papers

Miniature Concrete Prism Test: Rapid Test Method for Evaluating Alkali-Silica Reactivity of Aggregates


Existing test methods to assess alkali-silica reactivity of aggregates such as the accelerated mortar bar test (AMBT) has been shown to be less than satisfactory due to excessive false-positive and false-negative test results. While the concrete prism test (CPT) test is considered to be a more reliable alternative, the unusually long test duration (1 or 2 years, depending on the purpose) renders it unsuitable for routine evaluation of materials. This paper presents a new test method—the miniature concrete prism test (MCPT) that addresses the shortcomings of both the AMBT and the CPT test methods. The aggregates studied in this project were selected based on their established field performance. Results from this investigation indicate that the MCPT test method can reliably identify aggregate reactivity within a short duration of 56 days for the majority of aggregates, whereas it may take up to 84 days for some slowly reactive aggregates.