Linking reactivity test outputs to properties of cementitious pastes made with supplementary cementitious materials

Recently developed reactivity tests for supplementary cementitious materials (SCMs) have shown the ability to differentiate between inert and reactive materials. Two promising SCM reactivity tests were used to study ten different SCMs. The first method involves quantifying the heat release, bound water, and calcium hydroxide consumption of SCMs in a simulated pore solution (modified R³ test), and the second method is a lime strength test that quantifies lime mortar strength development. Tests on cementitious pastes with a 20% SCM replacement level were conducted to determine heat release, calcium hydroxide content, bound water, compressive strength, and bulk resistivity for 35 days. Moderate correlations between the modified R³ heat release at 10 days and 1 day and between modified R³ heat release and bound water were shown, which suggests the possibility of reducing test duration and using bound water, instead of the heat release. The calcium hydroxide consumption measured from the modified R³ test correlates strongly with CaO content in the SCM and moderately to paste bulk resistivity at 35 days, demonstrating the fundamental importance of measuring calcium hydroxide consumption. Correlations between modified R³ heat release and bound water and most other paste properties were generally poor, presumably because of the high acceleration in the modified R³ tests. The compressive strength measured from the lime strength test showed moderate to strong correlation to heat release, calcium hydroxide content, bound water, and bulk resistivity of cementitious paste at 1–35 days. The fundamental importance of these reactivity tests is therefore clearly validated.