Abstract
The use of recycled aggregate to reduce the over-exploitation of raw aggregates is necessary. This study analysed and categorised the properties of water-washed, fine and coarse, recycled aggregates following European Normalization (EN) specification. Because of their adequate properties, zero impurities and chemical soluble salts, plain recycled concrete was produced using 100% recycled concrete aggregates. Two experimental phases were conducted. Firstly, a laboratory phase, and secondly, an on-site work consisting of a real-scale pavement-base layer. The workability of the produced concretes was validated using two types of admixtures. In addition, the compressive and flexural strength, physical properties, drying shrinkage and depth of penetration of water under pressure validated the concrete design. The authors concluded that the worksite-produced concrete properties were similar to those obtained in the laboratory. Consequently, the laboratory results could be validated for large-scale production. An extended slump value was achieved using 2.5–3% of a multifunctional admixture plus 1–1.2% of superplasticiser in concrete production. In addition, all the produced concretes obtained the required a strength of 20 MPa. Although the pavement-base was produced using 300 kg of cement, the concrete made with 270 kg of cement per m3 and water/cement ratio of 0.53 achieved the best properties with the lowest environmental impact.
Highlights
In 2018, construction and demolition waste was 35.4% of the total waste (2277 million tonnes) generated in the European Union (EU) by all economic activities including households, of which only 54.2% was recovered [1,2]
The guidelines of the European Commission [3] are designed to encourage a change in production procedures to embrace a circular, more sustainable and eco-respectful model in which waste is re-introduced into production processes, reducing raw material over-exploitation and maximising material life cycles
The mix recommended by the manufacturer for the S was 0.3%–2.0% and 0.5%–1.5% for the P admixtures based on the weight of the ceTwo chemical admixtures were employed for concrete production: a multifunctional ment
Summary
In 2018, construction and demolition waste was 35.4% of the total waste (2277 million tonnes) generated in the European Union (EU) by all economic activities including households, of which only 54.2% was recovered [1,2]. Gress et al [12] described that the pavement produced with up to 25% of fine recycled concrete aggregates achieved adequate properties with a slight increase of shrinkage value with respect to that in concrete produced only employing coarse RCA. The concrete produced with 100% RCA (coarse plus fine recycled aggregated) obtained a lower compressive strength [4,27]. The fine RCA content from 0 to 15% had no significant effects on drying shrinkage of recycled concrete produced with 100% of recycled aggregate achieves pavement concrete. The second phase would verify if the worksite-produced physical properties, drying shrinkage and depth of penetration of water under pressur concrete achieved adequate properties similar to those obtained in the laboratory. Sustainability 2022, 14, x FOR PEER REVIEW produced concrete achieved adequate properties similar to those obtained in the laboratory
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