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RILEM TC 267 TRM– “Tests for Reactivity of Supplementary Cementitious Materials” recommends the Rapid Reliable Relevant (R3) test as a method for determining the chemical reactivity of supplementary cementitious materials (SCMs) in Portland cement blends. In this paper, the R3 test was applied to 52 materials from a wide range of conventional and alternative SCMs with the aim to validate such test. An excellent correlation was found between the cumulative heat release and the bound water determined following the R3 test method. Comparison of the R3 test results to mortar compressive strength development showed that all conventional SCMs (e.g. blast furnace slag and fly ashes) followed the same trend, with the notable exception of very reactive calcined kaolinitic clays. It is discussed, through an in-depth statistical regression analysis of the R3 reactivity test results and the 28 days relative compressive strengths, how reactivity threshold values for classification of the chemical reactivity of SCMs could be proposed based on the R3 test results.

Synthetic alkali-silica reaction (ASR) gels were produced and tested to investigate the effects of chemical composition (Ca/Si, Na/Si, and K/Si atomic ratios) on the gels' free swelling strain (e g,fr ) and restrained swelling pressure (P rs ). The gels were cast into disk-shape molds and exposed to distilled water after curing. Each gel's e g,fr was recorded over a period of 28 days, followed by measuring P rs , defined as the pressure required to fully reverse and eliminate the gel's free swelling under a drained configuration. Regression models were developed linking gels compositions to their swelling properties. The outcomes show that Na/Si and K/Si monotonically increase e g,fr . Increasing Ca/Si up to 0.23 drastically reduces e g,fr ; higher Ca/Si has modest effect on free swelling. P rs increases by increasing calcium up to a pessimum Ca/Si level; P rs decreases for higher Ca/Si. The value of (Ca/Si) pess is related to the alkali content of the gel. P rs also increases by increasing the gel's alkali content, while a (Na/Si) pess exists in the range 0.85-0.95. These observations are linked with the roles of alkalis and calcium in modifying the silica gel network.

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