Assessment on the engineering properties of ready-mixed concrete using recycled aggregates

• Concrete made with recycled concrete aggregate (coarse and fine).
• Concrete rubble was replaced by clay brick and tile with ratio from 0% to 67%.
• Reduction of slump, strength and elastic modulus compared to normal concrete.
• Insignificant changes in parameter of concrete as raising the brick and tile content.

The Chi–Chi earthquake, which took place in Taiwan in 1999, generated about 15–20 million tons of construction and demolition wastes (CDWs). Examination on recycled aggregates collected from this earthquake for producing new concrete is aim of the present work. In this study, properties of RAC prepared with mixed recycled aggregate containing clay brick and tile (CBT) were investigated. The results indicate that for fresh mix of RAC with presence of the CBT induced a slightly higher slump compared with normal concrete (NC). Test results also show that RAC is lower in unit weight and higher in air content than NC. For harden parameters, the 28 days – compressive strength and elastic modulus of RAC approximately decreased of 15–25% and 25% those of NC, respectively. And the flexural strength of RAC was lower 10–25% than that of NC. It is also revealed coarse aggregate contained CBT will make a negligible effect on the RAC. Moreover, for low water-to-cement ratio, the water absorption of recycled aggregate would significantly affects on the properties of RAC.