A small-scale thermogravimetric method to measure the chemical reactivity of supplementary cementitious materials

Partial replacement of ordinary portland cement (OPC) with supplementary cementitious materials (SCMs) is a ubiquitous and effective approach to design concrete mixtures with lower embodied carbon and improved durability compared to plain OPC concrete mixtures. However, the global supply of common industrial SCMs, like fly ash (a byproduct of coal combustion) and blast-furnace slag (a byproduct of steelmaking), is dwindling due to global decarbonization efforts and sustained demand from the concrete industry. The newly standardized ASTM C1897 rapid, relevant, and reliable (R3) test is an effective screening method to measure the chemical reactivity of potential SCMs. However, the sample quantity requirements impede the rapid-throughput screening of new SCM sources that may currently be available only in small quantities. The objective of the current study is to design and validate a small-scale modified R3 test to enable standardized characterization and rapid-throughput screening of novel SCMs. The results substantiate that the ASTM C1897 R3 bound water method can be performed with sufficient accuracy at a much smaller scale (i.e., 0.01 g of SCM per test) using the thermogravimetric method developed and validated herein.