Investigating the efficacy of curing methods on concrete containing reclaimed asphalt pavement aggregates

Abstract

Curing is adopted to prevent moisture loss and promote hydration in concrete. It influences the concrete up to a depth known as a curing affected zone (CAZ), while the remainder of the concrete remains unaffected. The quality of the CAZ indicates the effectiveness of a curing method. The aim of this study is to investigate properties of concrete that are sensitive to changes in curing method; these properties can subsequently be utilized to assess the effectiveness of different curing media. Moist curing and acrylic and wax-based curing compounds were adopted in this work. Conventional concrete mixes and concrete mixtures with partial replacement, by volume, of natural aggregate by reclaimed asphalt pavement (RAP) aggregate were studied. RAP aggregate is covered with a thin hydrophobic bituminous film, which affects the interfacial transition zone properties and the local water–cement ratio of the concrete. The mechanical properties, moisture-modified maturity, and durability properties of concrete were investigated for different curing regimes. The tests of strength parameters and moisture-modified maturity showed contrasting results with respect to the curing method and concrete mix. Meanwhile, durability properties displayed a consistent trend with respect to concrete mixes; they were prone to vary for different curing methods and should thus be considered in assessing a curing method’s effectiveness. Moreover, by adopting a two-stage mixing approach, improved strength characteristics were observed for RAP mixes, compared with the control mix.