Comportamiento adherente en hormigón con árido recicladocurva tensión adherente-deslizamiento

Resumo

In recent years, the use of recycled concrete has been widely recognized as a means to solve, reduce or minimize the environmental impact of construction and demolition waste. Many countries promote sustainable construction based on the reuse of coarse aggregates from crushed structural concrete, with the objective of preserving natural resources and reducing space for waste storage. The mechanical properties of the recycled concretes are unfavorable affected with the recycled aggregate replacement. Nevertheless, recycled aggregates from concrete demolition waste offer good enough features for use in structural reinforced concrete; indeed, with a recycled aggregate content up to 20% the reduction in mechanical properties is not conspicuous. Presently, reinforced concrete is present in almost all building and civil engineering works. This fact makes concrete bond strength one of the most important parameters in structural design. Thus, if recycled aggregates are to be commonly used in structural concrete, it is necessary to analyze the bond behavior between reinforcing steel and recycled coarse aggregate. In this research the bond behavior of recycled aggregate concrete (RAC) with different replacing percentages of natural coarse aggregate with recycled coarse aggregate (20%, 50% and 100%) was characterized. The results made it possible to establish the differences between the conventional concrete bond strength and the recycled concrete bond strength depending on the replacement percentage. Using the test results, it was found that bond strength decreases with the increase of the replacement percentage. Additionally when the relative bond stress (b /b,max) curve vs slip up to 1mm is analyzed, it was observed that, for a fixed b /b,max value, the measured slips are higher in recycled concretes than in conventional ones. Finally, using the experimental results, the bond strength-slip curve of the concretes was defined at different ages (from 7 to 365 days). Based on these results, it was observed that, no matter the concrete type (recycled or conventional) the shape of the normalized curve does not change.