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New study on use of RCA in structural concrete

A recent study funded by WRAP (Waste & Resources Action Programme) analyses whether the strength and performance of structural concrete made using recycled concrete aggregates (RCA) can be predicted by applying the same design formulae used for concrete containing primary aggregates.

The aim of the project was to identify whether the use of RCA affects the applicability of engineering property relations for concrete-based compressive strength, given in structural design Eurocode 1992 (EC2). The study also assessed whether the ultimate strength of concrete structural members containing RCA can be predicted through compressive strength testing, also as defined in EC2.

A variety of tests were completed during the programme, the results of which are interpreted and discussed in the report. These include 28-day tests on hardened concrete, creep and drying shrinkage tests, pull-out tests, full-scale flexural and shear tests on beams and the variability of compressive strength and its effects when RCA is present in structural concrete.

The report provides a number of conclusions and encourages designers, in most cases, to adhere to EC2 design formulae and material property relations when designing concrete structural components from the RCA materials considered in the study.

According to John Barritt, technical advisor for aggregates at WRAP, publication of the report is significant as it removes further barriers to the use of sustainable aggregates in construction.

He said: ‘The report provides concrete designers with the guidance they need to accommodate RCA in structural concrete. It addresses the use of differing types of RCA, different mix proportions and different strength classes. Where the report concluded EC2 could not provide designers with the information required, further tests are suggested that will resolve any outstanding issues.’

A copy of the report, ‘Engineering properties of concrete containing recycled aggregates’, can be downloaded from www.wrap.org.uk; or for further assistance contact the  WRAP?construction team on tel: (0808) 100 2040.

 
 

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