Influence of recycled aggregates on the mechanical and tribological behavior of concrete

The objective of this study is to evaluate the performance of a current concrete using recycled aggregate. Physical and mechanical tests of characterization were conducted on the aggregates to better understand the effects of absorptions. An experimental program to test fresh concrete was conducted regarding the workability and tribology for different substitutions of recycled aggregates with a constant and variable W/C ratio. Mechanical strength tests were also performed. The results on aggregates clearly show a lower density for recycled aggregates which is reflected in the fresh concrete according to the substitution. The rate of porosity is important, reaching 17% with an uptake of 7%, greater than that of the natural gravel. The mechanical tests confirm low wear resistance. With a W/L constant, the drop in workability is significantly dependent on the content of the % recycled, while the mechanical strength decreases only slightly. In terms of tribology, yield interface friction (τ) increases with the percentage of recycled aggregate and the viscous constant (η) of 100% recycled, reaching twice that of natural concrete. The test with constant workability and a W/C ratio variable causes a fall in compressive strength values approaching 25%. A third formulation dosed in adjuvant, with workability and constant volume of dough gives resistance values ​​comparable to that of the reference concrete with a yield interface equivalent to that of the reference concrete and a slightly higher viscous constant.