| Recycled aggregate concrete is the recycled concrete aggregates that derived from waste concrete being crushed, which replaced the concrete made from natural aggregate in certain ratio. It has the advantage of light-weight and favorable thermotechnical characteristics, etc. Currently, it has been a hot issue on the study of recycled concrete. The utilization of waste concrete can not only dispose the abandoned construction waste to protect ecological environment, but also save natural stone materials and decrease the dosage of cements to save social recourses, which is of important significance to the sustainable development of construction resources with its good economic potential and social benefits. Numerous studies have been done on recycled concrete by many scholars. In this paper, based on the works previously, an additional study has been made, which puts the emphasis on the carbonization, high temperature properties of recycled concrete and the flexural performance of recycled concrete beam that originated from different recycled aggregates. The main conclusions are as following:(1) The carbonized experiment on 28-day age period of recycled concrete, originated from all kinds of recycled aggregates, shows that recycled concrete is easier to be carbonized than common concrete; when the replacement rate of recycled aggregates is 0 to 75%, the carbonation depth increased with the rise of it; when the replacement rate is 75%, the carbonation depth of recycled concrete that originated from all kinds of recycled aggregates is easy to appear large variety as the carbonation depth has great differences in recycled concrete from different recycled aggregates; the splitting tensile strength of carbonized recycled concrete is higher than normal concrete; when the replacement rate is 0 to 50%, the splitting tensile strength of recycled concrete increased with it but decreased with increasing rate when it is 50% to 75% and it is irregular when the replacement rate is above 75%.(2) Research on high temperature properties of recycled concrete indicates that high temperature has a significant effect on the residual compressive strength and mass loss of recycled concrete and the there has little difference in the residual compressive strength of recycled concrete that originated from different recycled aggregates; the mass loss rate of recycled concrete increased with the decrease of recycled aggregates and the increase of the temperature; the replacement rate has an obvious influence upon slump and the slump increased with the rate when it is 25% to 50%. While the slump begins to decrease when the rate is above 50% and it declined obviously in 50% to 75%.(3) The analysis on normal section bending bearing capacity of all kinds of recycled concrete show that there has little difference in the bending resistance and bearing capacity of recycled concrete beam from different recycled aggregates; bearing capacity calculated from normal section of common concrete beam is higher than recycled concrete; the normal section bearing capacity of recycled concrete beam can be calculated in accordance with the present codes of common concrete; when the replacement rate is 0 to 50%, the bearing capacity value of normal section raised with the decrease of replacement rate.(4) Research on the crack width of recycled concrete beam indicates that the fluctuation of the crack width changed with the load is greater than common concrete; the relationship in the size of the crack width of the beam between recycled concrete and common concrete is random; it is inappropriate to apply present codes of common concrete to calculate the crack width of recycled concretes.This paper studied the carbonization, high temperature properties of recycled concrete and the flexural performance of recycled concrete beam that originated from which is a supplement to previous study, which can provide references for the study of recycled concrete from different recycled aggregates. |
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