Petrographic method to semi-quantify the content of particles with reactive components and residual mortar in ASR-affected fine recycled concrete aggregates

A petrographic method is proposed to semi-quantify the content of particles with reactive phases in fine recycled concrete aggregates (FRCA) affected by the alkali-silica reaction and the residual mortar (RM) adhered to them. This method is compared to the image analysis method. Quartered FRCA samples are studied by three petrographers, and the results are compared. Finally, the potential reactivity of the samples is evaluated by the accelerated mortar bar test (AMBT). According to the AMBT and petrographic method, the samples are qualified as potentially reactive, with a low degree of reactivity. The method is easy to perform and fast (compared to image analysis), but the results obtained by three petrographers show some differences that can mainly be attributed to the visual estimation of RM. Although more studies are needed to verify the effectiveness of the proposed method, the implemented technique shows great potential to semi-quantify reactive components in FRCA particles.

Automated summary

A petrographic method is proposed to semi-quantify reactive components in fine recycled concrete aggregates affected by the alkali-silica reaction and residual mortar. The method is compared to image analysis method and tested on quartered FRCA samples by three petrographers. Despite showing great potential, differences in results obtained by the three petrographers mainly stem from visual estimation of residual mortar.