Risk of ASR in coating mortars incorporating glass aggregates and a Portland–limestone cement

Abstract

As the cement content is one of the parameters that control alkali–silica reaction (ASR), this study examined its influence on the expansion of glass mortars. The mortars had volumetric ratio of 1:4 (cement: aggregate) and various aggregate compositions, obtained using replacement ratios of natural sand with waste glass, of 0, 20, 50 and 100%. A volumetric ratio 1:4 was chosen because it is a current composition for cementitious coating mortars. In fact, mortar mixes with increased cement content can lead to erroneous conclusions for in situ mixtures with reactive aggregates. It is concluded that it is feasible to produce glass mortars without deleterious ASR expansion depending on the amount of cement used. For normal cement/aggregate ratios for coating mortars (1:4, in volume), a CEM II/B-L 32.5 N mortar with glass incorporation has a low ASR risk.

Keywords:

• glass aggregate
• mortar
• coating
• ASR
• limestone cement
• waste management

Acknowledgements

The authors wish to acknowledge the support of the Laboratório Nacional de Engenharia Civil (LNEC); Vidrologic – Gestão de Resíduos e Ambiente, Lda.; CERIS-ICIST; IST, and the University of Lisbon. Thanks are also due to FCT (Science and Technology Foundation) for support under the project IMPROVE (PTDC/ECM/115486/2009).