Effect of carbonation on physical sulfate attack on concrete by Na2SO4

Concrete carbonation is regarded as a significant cause of reinforcement corrosion in buildings. This research paper will present another detrimental effect of concrete carbonation on the concrete durability. Concrete cylinders placed in an accelerating carbonation chamber for 10 and 20d were partially immersed in a 10% Na2SO4 solution. After 28, 60, 120, and 240d exposure, the mass loss of the concrete specimens was measured, and the damage mechanism checked by means of XRD analysis, NMR, ESEM and EDS. The results showed that a larger carbonation depth in the concrete caused more concrete scaling, and that sulfate crystals were also identified in the carbonated concrete. Due to their susceptibility to carbonation, blended concretes containing fly ash and slag showed more scaling than Portland concrete. Therefore, the "physical sulfate attack on concrete" can be more accurately described as the "physical sulfate attack on carbonated concrete." (C) 2018 Elsevier Ltd. All rights reserved.