Durable Structural Concrete Using Fine and Coarse Recycled Aggregates (Type A and Type B)

Abstract

The use of Recycled concrete aggregate (RCA, type A) and mixed recycled aggregate (MRA, type B) is an alternative for structural concrete production to reduce natural resource exploitation and landfilling of construction waste. However, the lower quality of recycled aggregate compared to that of natural aggregate, and consequently the lower durability of recycled concrete, make it necessary to limit the percentage of replacement of raw aggregates by recycled aggregates. The objective of this study is to analyse the adequacy of using different percentages (following European standards) of coarse and fine type A and type B recycled aggregates for structural concrete production. All the concrete mixtures were produced using 300kg/m3 of cement and an effective water: cement ratio of 0.48 to be exposed to the XC1-XC4 environment. In addition, the conventional concrete (0% recycled aggregates) was also produced using an effective water: cement ratio of 0.52. The physical and mechanical properties, drying shrinkage values, and durability property of sorptivity and water penetration values were determined in all the produced concretes. It was concluded that the concrete produced with up to 60 % coarse RCA and 30 % fine RCA (type A) aggregates achieved adequate properties for structural concrete. In addition, the use of MRA mixed recycled aggregate (type B) was also possible for structural concrete production when it was employed in the replacement of natural aggregates up to 40% for coarse MRA and 15% for fine MRA simultaneously.

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