Abstract
Carbonation durability is an important subject for recycled coarse aggregate concrete (RAC) applied to structural concrete. Extensive studies were carried out on the carbonation resistance of RAC under general environmental conditions, but limited researches investigated carbonation resistance when exposed to chloride ion corrosion, which is an essential aspect for reinforced concrete materials to be adopted in real-world applications. This paper presents a study on the carbonation durability of two generations of 100% RAC with the effect of chloride ion corrosion. The quality evolution of recycled concrete coarse aggregate (RCA) with the increasing recycling cycles was analyzed, and carbonation depth, compressive strength and the porosity of RAC were measured before and after chloride ion corrosion. The results show that the effect of chloride ion corrosion negatively affected the carbonation resistance of RAC, and the negative effect was more severe with the increasing recycling cycles of RCA. Chloride ion corrosion led to a decrease in compressive strength, while an increase in carbonation depth and the porosity of RAC. The equation of concrete total porosity and carbonation depth was established, which could effectively judge the deterioration of carbonation resistance of RAC.
Highlights
The application of recycled coarse aggregate concrete (RAC) in non-structural and structural concrete can effectively solve the shortage of natural coarse aggregate (NCA) and the environmental crisis caused by waste concrete, which is considered as an inevitable way for the sustainable development of concrete engineering
This paper presents a study on the carbonation resistance of two generations of 100% RAC with the effect of chloride ion corrosion
NAC and RAC with two generations of 100% RCA were considered in the present study, with the aim of investigating whether concrete with significantly different coarse aggregate resulted in a different evolution of carbonation resistance induced by chloride attack and evaluating whether the carbonation resistance of multi-recycled coarse aggregate could meet the requirements of structural concrete
Summary
The application of RAC in non-structural and structural concrete can effectively solve the shortage of natural coarse aggregate (NCA) and the environmental crisis caused by waste concrete, which is considered as an inevitable way for the sustainable development of concrete engineering. The obtained results confirmed the potential use of high-quality recycled aggregate originating from local sources in some applications in building structures and indicated the benefits of using recycled materials These studies confirm the suitability of multi-recycled coarse aggregate concrete as materials for reinforced concrete. Extensive studies were carried out on the carbonization durability of RAC under general environmental conditions [8,9,10,11], but a limited number of researches investigate its carbonization performance when exposed to the environmental condition of chloride ion corrosion [12,13], which is an essential aspect for reinforced concrete materials to be adopted in real-world applications. It is worth highlighting that research on the carbonation resistance of RAC, especially the influence of chloride ion corrosion on it, will help us to have a deeper understanding of the durability failure of recycled concrete, and can more accurately predict the service life of the structure
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