Mechanical Properties and Permeability of Recycled Aggregate Concrete at Low Water/Binder Ratio

This paper presents an experimental research on mechanical properties and permeability of recycled aggregate concrete (RAC). Concretes at a water/binder ratio of 0.255 were broken into recycled aggregates (RA). A type of thermal treatment was employed to remove mortar in RA. Tests were conducted on aggregate to measure water absorption and crushed values, and on RAC and natural aggregate concrete (NAC) to measure compressive strength, tensile splitting strength, and fracture energy. The results revealed that both gravel damage and mortar attached can significantly influence the water absorption and crushed value of RA. The mechanical properties RAC were obviously lower than those of NAC at an identical mix proportion. Moreover the removal of mortar caused a decrease in mechanical properties. The behavior of the chloride ion penetration of RAC under compressive loading is different that of NAC, which may be related to the flaws of RA. Further experimental research is needed to identify its mechanism.