Dynamic Compressive Behavior of Recycled Bricks Aggregate Concrete Under SHPB Tests

The growth of urbanization in the last decades has already created a considerable number of Construction and Demolition Waste (CDW) materials. Concrete, bricks, glass, and tiles are widely used in residential construction accounting for a large proportion of CDW. The use of CDW as aggregates in the new concrete mixture has been recognized as an attractive approach to conserve natural resources and reduce the environmental influence of the construction industry. Nowadays the application of crushed bricks as coarse aggregate has recently been a reasonable target of research. However, construction structure and material can be subjected to vehicular impacts (e.g., cars, trucks, trains, boats, aircraft, etc.) and to other complex fast varying dynamic loads during their service life. Given that response of different aggregate concrete can be quite different due to its sensitivity to strain rate effects, the high-strain rate compressive behavior of recycled bricks aggregate concrete (RBC) is with little attention yet, the availability of this data is crucial for the definition of the constitutive laws accounting for the strain rate effects and allows for the evaluation of the structural response under fast varying loads such as impacts and blasts. The dynamic compressive behavior of RBC under high strain rate is investigated by large diameter Split-Hopkinson Pressure Bar (SHPB, diameter is 155 mm) in this study. Specimens are prepared by four different substitution levels respectively, from 0% (natural plain concrete) to 100% (all coarse aggregate is substituted by crushed bricks). A total of 36 specimens (with a diameter of 150 mm, and a height of 75 mm) are tested under three different air pressure corresponding to three strain rates. Tests can reach a maximum strain rate of 100 s⁻¹. The stress-strain relationships and the dynamic increase factor (DIF) for RBC under different strain rates are obtained and discussed. The results show that RBC is quite strain-rate sensitive constructional material.