A Review on Alkali-Silica Reaction Evolution in Recycled Aggregate Concrete

Abstract

Alkali-silica reaction (ASR) is one of the major degradation causes of concrete. This highly deleterious reaction has aroused the attention of researchers, in order to develop methodologies for its prevention and mitigation, but despite the efforts made, there is still no efficient cure to control its expansive consequences. The incorporation of recycled aggregates in concrete raises several ASR issues, mainly due to the difficult control of the source concrete reactivity level and the lack of knowledge on ASR’s evolution in new recycled aggregate concrete. This paper reviews several research works on ASR in concrete with recycled aggregates, and the main findings are presented in order to contribute to the knowledge and discussion of ASR in recycled aggregate concrete. It has been observed that age, exposure conditions, crushing and the heterogeneity source can influence the alkalis and reactive silica contents in the recycled aggregates. The use of low contents of highly reactive recycled aggregates as a replacement for natural aggregates can be done without an increase in expansion of concrete. ASR expansion tests and ASR mitigation measures need to be further researched to incorporate a higher content of recycled aggregates.

Durability of Blended Cements Made with Reactive Aggregates

“…However, in the expansion curves plotted in Figure 6 and Figure 7 , the first and second zones are not clearly separated. Furthermore, contrary to what could have been expected [ 30 , 31 , 32 , 33 , 34 ], there was no plateau at the end of the curves, i.e., there is a final slope that is different from zero. This is possibly because cement replacement slowed down the ASR reaction; accordingly the curve was not yet flat.…”

Recycled Aggregates Produced from Construction and Demolition Waste for Structural Concrete: Constituents, Properties and Production

“…Nevertheless, investigations on this topic show that CRA are not expected to lead to alkali–silica reactions [ 46 ] unless CDW includes a relevant portion of pavement waste [ 42 , 48 ]. It should be noted that some authors have questioned the suitability of the conventional tests used for NA when assessing the reactivity of CRA [ 49 ].…”

Some Remarks towards a Better Understanding of the Use of Concrete Recycled Aggregate: A Review

“…It is well known that alkali-silica reaction (ASR) is one of the major causes of concrete degradation. In the case of RAC, this problem can be significant depending on the percentage of RCA as a substitute of NA and because of the obvious crushing process [22].…”

“…Basically, the untreated RAC does not act as well as NAC in terms of mechanical properties and durability performance [22][23][24][25][26]. However, the applicability of the RCA to concrete is clear [27,28], and RCA is practically being used for concrete production [10,29].…”