A new reactivity test for supplementary cementitious materials (TC TRM 267) applied on non-ferrous slags and sludges

Non-ferrous metallurgy residues are challenging materials in terms of reuse as construction materials. First and foremost, their environmental quality is often problematic, and second, their technical properties usually only... [ view full abstract ]

Non-ferrous metallurgy residues are challenging materials in terms of reuse as construction materials. First and foremost, their environmental quality is often problematic, and second, their technical properties usually only meet the requirements of low value applications. The H2020 METGROW+ project aims to reach zero-waste solutions by further processing in a holistic approach of 1) recovering more valuable metals, while at the same time 2) removing harmful substances, and 3) upgrading the technical quality of the cleaned mineral residue for the purposed use as construction material.

While performant test methods are in place to screen the environmental quality of a product, current standard reactivity testing methods for supplementary cementitious materials (SCMs) are felt to fall short on many levels, in particular for high replacement levels or multicomponent systems. Test methods under consideration should supply results more rapidly than the standard compressive strength testing regimes, they should be straightforward and robust to execute, and should not require expensive equipment or advanced levels of training of practitioners. The goal of RILEM Technical Committee 267-TRM (Tests for Reactivity of Materials) is therefore to evaluate the existing reactivity tests and develop a pre-normative recommendation for rapid supplementary cementitious material (SCM) reactivity tests. The first results show that measurement of the heat flow or bound water of mixes of the SCM with slaked lime and additional alkalis relates well to the strength development for a range of conventional SCMs such as coal combustion fly ashes, natural pozzolans and iron blast furnace slags. In a next step the scope of the test method is explored by testing a wide range of materials that are currently not used as SCM. This contribution shows the results of the SCM reactivity tests on residues from non-ferrous metallurgy slags and sludges that went trhough innovative extractions and shows contrasting results, revealing potentials for zero-waste valorisation of the selected residues.