Critical assessment of rapid methods to qualify supplementary cementitious materials for use in concrete

In this study, several tests for supplementary cementitious materials (SCMs) were evaluated to find the best methods to rapidly screen out inert materials, measure overall reactivity, and differentiate between pozzolanicity and latent hydraulicity. The R-3 matrix and lime reactivity tests were found to be the most effective at quickly screening out inert materials. However, slow-reacting materials may appear to have low reactivity in both tests and extending the test duration better depicts material reactivity. Additionally, SCMs with higher alumina content perform better in the R-3 tests due to the higher heat release and more bound water associated with the formation of calcium aluminate hydrates compared to calcium silicate hydrates, creating reactivity bias when compared to SCMs with lower alumina content. Measuring the calcium hydroxide content of R-3 pastes, through thermogravimetric analysis or single point mass loss, can also differentiate between pozzolanic and hydraulic materials.

Automated summary

This study evaluated several tests for supplementary cementitious materials (SCMs) to quickly screen out inert materials, measure overall reactivity, and differentiate between different types of reactivity. The R-3 matrix and lime reactivity tests were found to be the most effective methods, but slow-reacting materials may show low reactivity in both tests. Extending the test duration can better represent material reactivity. Additionally, SCMs with higher alumina content perform better in the R-3 tests, but this creates a reactivity bias when compared to SCMs with lower alumina content. Measuring the calcium hydroxide content of R-3 pastes can differentiate between pozzolanic and hydraulic materials.