Long term performance of recycled concrete beams with different water-cement ratio and recycled aggregate replacement rate

The purpose of this study is to reveal the service performance of recycled aggregate concrete(RAC)components for different values of water-cement ratio and replacement rate of recycled coarse aggregate(RCA).Generally,the concrete strength decreases with the increase of the replacement rate of RCA,in order to meet the strength requirements when changing the replacement rate of RCA,it is necessary to change the water-cement ratio at the same time.Therefore,the axial compressive strengths of prism with 25 mix proportions,the short-term mechanical properties and long-term deformation properties of reinforced concrete beams were tested respectively by changing water-cement ratio and RCA replacement rate.The bearing capacity and the strain nephogram of samples under different loads were obtained using the Digital Image Correlation(DIC)method,and a self-made gravity loading experimental device was used for long-term deformation investigation.Results showed that the damage pattern of RAC was the same as that of natural aggregate concrete(NAC),but the brittleness was more pronounced.The brittleness of concrete before failure can be reduced more effectively by adjusting the replacement rate of RCA than by adjusting the water-cement ratio.The water-cement ratio has an evident influence on the axial compressive strength and early creep of concrete,while the replacement rate of RCA has a remarkable effect on the long-term deformation of the concrete beams.

Basic Mechanical Properties and Microstructural Analysis of Recycled Concrete

The regeneration aggregate, natural aggregate, POO42.5 R Portland cement, coal fly ash, and slag powders S95 graining blast furnace, homemade P（AA-co-MA）/PEG carboxylic acid water reducing agent, were used together with recycled concrete aggregate in different regeneration rates to prepare recycled concrete （RC）. The influences of different renewable aggregate ratios on the basic RC replacement mechanical properties, uniaxial compression stress and strain curve, and the elastic modulus and rebound value were investigated.The results show that RC mechanical properties decreases with renewable aggregate replacement rate increasing. The prolongation can reduce the reduced span.