STRENGTH OF CONCRETES PREPARED WITH NATURAL AND RECYCLED AGGREGATES AT DIFFERENT MOISTURE CONDITIONS

摘要

The influence of moisture conditions of natural and recycled aggregates on the properties of the strength of the hardened concretes was highlighted in this study. Natural and recycled aggregates were incorporated into concrete in different combinations. The aggregates were controlled at air-dried, oven-dried and saturated-surface dried (SSD) states respectively prior to use. The results show that replacements of up to 50% of natural aggregates by recycled aggregates do not have significant detrimental events on the strength of the concrete producsd. The effect of the moisture states of the aggregates on the strength of the concretes prepared with oven-dried and SSD-state aggregates at early age (i.e. 3 and 7 days) was noticeable. The concrete prepared with the air-dried aggregates achieved the highest average strength values at various ages. For the concrete prepared with recycled aggregates at the SSD condition, the increase in proportion of recycled aggregates significantly reduced the splitting tensile strength. The results suggested that an air-dried aggregate that contains not more than 50% recycled aggregate is optimum for producing normal strength recycled aggregate concrete.