| In this paper,a new multi-factor coupling simulation method with the advantages of simple operation and precise load control is proposed.However,the rationality and accuracy of this method need to be further verified by experiments compared with the multi-factor coupling simulation method with loading device.In this paper,the durability of recycled concrete under multi-factor coupling action under three intermittent load modes and continuous load modes is compared and analyzed,and the laboratory simulation method of recycled concrete under multi-factor coupling action is determined.Three kinds of intermittent load mode and continuous load mode are designed to test the durability of concrete under the coupling action of load and environmental factors.The test design is only subject to the three working conditions of load、Load and corrosion coupling and load and corrosion freeze-thaw cycle coupling test.Three kinds of recycled concrete with different strength grades(C30,C40 and C50)are made and three kinds of stress levels(20)are considered%,40%and 60%).The main conclusions are as follows:(1)In the intermittent loading mode,with the increase of concrete strength level,the strength loss is smaller,but it’s not very significant,which is consistent with the rule of continuous loading mode with the increase of concrete strength level.(2)In the intermittent loading mode and the continuous loading mode,with the increase of the compressive stress level,the strength of recycled concrete first increases and then decreases,because at the low stress level(0.2fc)the random microcracks in recycled concrete are closed,the concrete is more dense,and the ability to resist the coupling effect is enhanced.Then with the increase of compressive stress level,the random microcracks in concrete gradually evolve and develop,and their ability to resist the coupling effect is degraded.(3)In the intermittent load mode,on the one hand,at the low stress level,with the increase of the number of loading alternations,the concrete interior is gradually compacted,but the degree of compaction becomes slower,because under the lower load,the concrete compaction process is certain,and it can not be infinitely compacted;on the other hand,with the increase of the load level,the more the number of loading alternations,the more the concrete The internal damage of the concrete gradually accumulates and its strength loss increases.(4)The results show that the deviation between the compressive strength of recycled concrete under intermittent loading and that under continuous loading is less than 15%,which shows that the laboratory simulation method of using intermittent loading to simulate long-term loading is reasonable The results of P2 scheme(repeated load alternate 2 times)are the closest to the continuous load mode.The regression equations of compressive strength loss rate,compressive strength and stress level of recycled concrete under the coupling effect of load、load corrosion coupling and load and freeze-thaw corrosion are fitted by MATLAB,and the coefficients of fitting equations of intermittent load and continuous load are analyzed.The results show that the compressive strength loss rate of recycled concrete under intermittent loading has a good correlation with the strength loss rate under continuous loading,and P2 loading mode has the best correlation with the strength loss rate under continuous loading. |
