Evaluation methods of alkali-silica reaction in concrete with recycled aggre-gates

Miguel Barreto Santos, Jorge de Brito, António Santos Silva

Abstract


Alkali-silica reactions (ASR) are one of the causes of chemical degradation of concrete with natural aggregates (CNA) that compromise its durability. The introduction of recycled aggregates (RA) in concrete creates changes in their properties and differences in the results of the evaluation tests of ASR. Existing bibliography emphasizes special care in the evaluation of RA and concrete with recycled aggregate (CRA) for ASR and changes are proposed to the existing test methods. There are proposals to change the accelerated test of mortar and concrete with RA to accelerate the reactions and recommendations to prevent changes in the characteristics of the RA, during the preparation of samples. Some articles recommend the pre-saturation of the AR, due to its absorption of water, to avoid significant variations in the results of expansion of concrete samples from early ages. This article aims to briefly describe the characteristics of CRA and ASR presenting comments from existing bibliography to the evaluation methods of ASR in CRA and CNA.

Rev. ing. constr. [online]. 2009, vol.24, n.2, pp. 141-152. ISSN 0718-5073.  http://dx.doi.org/10.4067/S0718-50732009000200002


Keywords


Concrete with recycled aggregates; alkali-silica reaction; durability; degradation

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