Sulfate ingress in recycled concrete immersed in sodium sulfate solution for 10 years

SANTILLAN, L.R; VILLAGRAN ZACARDI Y.A; BENITO DAMIÁN E; ZEGA C. J.

Lisboa

Workshop; Workshop on External Sulfate Attack; 2016

RILEM - LABORATÓRIO NACIONAL DE ENGEHARIA CIVIL

Sulfate ions ingress into concrete matrix through pore solution, and interact with hydration products resulting in potential detrimental effects. A main concern regarding this deterioration process is the rate at which sulfate can penetrate into concrete, and for the particular case of recycled concrete, the increased porosity due to attached mortar in aggregate particles is a potential disadvantage. Moreover, hydration products within recycled aggregate particles can react with ingressing sulfates, causing more internal damage. This paper presents sulfate ingress profiles in conventional and recycled concrete specimens immersed in 50 g/l sodium sulfate solution for 10 years. Four concretes with w/cm= 0.35 and with 0%, 50%, 75% and 100% of coarse recycled aggregate were tested. Sulfate content was determined up to 3 cm depth by chemical analysis and XRF. Complementary thermogravimetric analyses were alsoperformed. Limited influence of recycled aggregate was obtained and not in correspondence with the increased porosity