Research On The Physical And Mechanical Properties And Mathematical Statistics Of Recycled Concrete

The resource utilization of the Construction waste, which not only meeting the rapid industrialization and urbanization process of china, but also resolving environmental problems. It's a good way for the construction waste disposal.Recycled aggregate is the waste concrete block after crushing, cleaning, screening,and it can be used as the coarse aggregate. For the different physical properties between the recycle aggregate and natural aggregate, the recycle concrete preference many differences from the formal concrete. Based on the mathematical statistics, this paper studies the physical properties of recycled coarse aggregate and the compressive strength of recycled concrete, and combines the macroscopic and microscopic damage, elaborating the destruction of recycled concrete Mechanism.Firstly, the proportion of the substituted natural aggregates was 0%, 30%, 50%,80% and 100%, respectively, forming the mixed aggregate. The water absorption,crushed Index and apparent density of the aggregate were measured. The results show that the mixed aggregate formed with recycled aggregate and natural aggregate is consistent with the law of mixing. Based on the 45 test data of recycled aggregates from different sources in some literatures, the correlation between the three physical performance indexes was analyzed. It was found that the fitting value of water absorption and apparent density by binomial and polynomial relationship would be better than linear The fitting value is more accurate. Because of the large discreteness between the water absorption and the crushing value, the formula of them cannot to be obtained.Secondly, the substation of recycled coarse aggregate in recycle concrete is 0%,30%, 50%, 80%, 100%, each group tested 20 or 21 test species. The results show that the strength of recycled aggregate concrete is equivalent to that of ordinary concrete when the substitution rate is 30% or less. Under the condition of high W/C, the content of recycled aggregate has little effect on the standard deviation of compressive strength of recycled concrete In the case of low gray-water ratio, the significant level of a = 0.5, the performance of the recycled concrete is the same as that of the recycled concrete. The intensity probability distribution is also consistent with the normal distribution.Finally, in order to observe the damage of recycled concrete, three kinds of recycled concrete with different mixing ratio and recycled coarse aggregate were used in medium and low strength recycled concrete. The failure form was similar to ordinary concrete. The damage is mainly due to the transition zone with the interface associated with the new mortar. For the high-strength recycled concrete, the method of nanoindentation is used to test out: the interface of the coarse aggregate rock - the interface of the new mortar interface is about 55?m, and the interface of the coarse aggregate rock-the interface of the old mortar interface The hardness of the new mortar is higher than that of the old mortar. The hardness of the new interface is similar to that of the old interface, so the recycled coarse aggregate becomes the weak link of the system.