Degradation Resistance and Reliability Analysis of Recycled Aggregate Concrete in a Sulfate Environment

Abstract

Resistance to sulfate degradation is an important index used to measure concrete's durability. In this study, recycled aggregate concrete (RAC) with a 0%, 30%, and 50% recycled coarse aggregate substitution rate and a 0% and 15% recycled fine aggregate replacement rate was used as the research object, and its degradation resistance was evaluated by the mass loss rate and the relative dynamic modulus of elasticity. e degradation products were studied and analyzed with SEM scanning electron microscopy and XRD phase analysis. e relative dynamic modulus of elasticity was selected as the degradation index, the RAC concrete's degradation resistance was modeled by Wiener, and the reliability curve was obtained. e results showed that expansion products, such as gypsum and Ettringite, were produced in RAC concrete in a dry-wet sulfate cycling environment, and such defects as pores and voids were filled in the initial stage. e stress the expansion products exerted in the later stage caused the concrete to crack and peel, which demonstrated that the fluctuation law of mass and the dynamic elastic modulus increased first and then decreased. e recycled coarse aggregate substitution ratio's effect on RAC concrete is higher than that of recycled fine aggregate. e reliability curve established by the Wiener model can reflect the reliability of RAC concrete under different cycles well and can obtain RAC concrete's sulfate degradation resistance life with different aggregate substitution rates.

Durability and life prediction of fly ash geopolymer concrete in corrosion environments caused by dry and wet circulation

“…With more drying and wetting cycles, more SO 4 2− invades TWGPC, leading to a rapid chemical reaction. The resulting product absorbs water and generates a swelling force, which destroys the internal structure of TWGPC, leading to an increase in the relative value of the decline rate of the dynamic elastic modulus (Cao et al 2020).…”

“…To effectively solve the problems of a low utilization rate of solid waste and large environmental pollution (Zhao et al 2020), FA can be used to partially replace cement, tailings and waste rock can be used to replace natural sand, and breakstone can be utilized to prepare concrete (Dandautiya and Singh 2019).…”

Examining The Mechanical and Durability Properties of Concrete Containing Recycled Fine Aggregates Possessing Different Contamination Levels

“…In some of previous studies, no signi cant negativity was observed in sulfate resistance of concrete when using RA. They explained this result with RFAs absorbing more sulfate solution because of their more porous structure(Cao et al 2020). Similar results were observed also in the study carried out by Bing et al(Qi et al 2017).…”