Effects of Recycled Concrete Aggregate Surface Treatments on Drying Shrinkage of Recycled Aggregate Concrete

Graduate Thesis Or Dissertation

Citations

Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/9g54xj04d

Abstract

The use of recycled concrete aggregate (RCA) in concrete construction is a practice that is increasing in use with a general movement toward more sustainable and environmentally responsible construction practices. The environmental benefits include reducing landfill use from building construction and reducing effects of mining for new aggregates. The surface characteristics of RCA differ from natural aggregates due to the remaining cement paste adhered to the original aggregate which result in lower aggregate density and higher absorption. An experimental study was carried out to determine the effects on concrete of various RCA surface treatments, which included a silica-cement mixture, acrylic coating, surfactant solution, and water saturation, intended to alter RCA surface characteristics. The effects on aggregate properties, fresh concrete properties, and hardened concrete properties were examined. The use of RCA at a 25% substitution rate for natural aggregate appears effective at reducing drying shrinkage and increasing compressive strength using untreated, acrylic treated, and water saturated RCA, depending on the intended use of the final concrete product.

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