INFLUENCE OF CRUSH VALUE INDEX ON COMPRESSIVE STRENGTH OF RECYCLED AGGREGATE CONCRETE

Crush value index is a key parameter for measurement of coarse aggregate strength performance. In this paper eight groups of crush value indexes were tested for the recycled aggregate made of waste concrete gathered from three different removed construction plants. Through the experiment research and combined with comparison of research results of domestic and foreign scholars,the results show that the crush value index of recycled aggregate is2 ~ 2. 5times greater than that of nature aggregate. Meanwhile the crush value index of saturated face dry state is increased by 7. 22% ~ 18. 20% as compared with that in air dried condition. Based on which twenty-six groups of compression strength tests were carried out to research the regularity for change in compressive strength of aggregate from can different source and different replacement rate. The testing result is presented that the recycled aggregate has larger variability,which makes test results differ greatly or be poles apart. For the exploration of relation between aggregate strength and recycled concrete compression strength,the twelve groups of specimens were comparatively analysed in air dried and saturated face dry condition. The least square fitting and result analysis show that the compression strength of RAC may not always be decreased with increase in crush value index and decrease in strength of the aggregate.