Research On The Compound Method And Physical-Mechanical Properties Of Modified Rubberized Concrete

Rubber is modified by modifiers to improve the cohesiveness between rubber particles and cement paste,and the performance of rubberized concrete becomes better. The finished studies show that the modified rubberized concrete has high frost resistance and will have a good application prospect in hydraulic engineering. But the mechanical properties of modified rubberized concrete have not been studied perfectly. Therefore, the compound method and physical-mechanical properties of modified rubberized concrete are studied in this paper, which is subsidized by special scientific research project of public service industry of ministry of water resources(201301027).The main contents and conclusions are as follows:(1) The selection principle of modified rubberized concrete’s mix proportion, the strength ratio of the standard rubberized concrete to the standard concrete is 0.71~0.83, was achieved firstly when we researched the compound method. Then the rubberized concrete’s mix proportion was confirmed by the analysis of slump values and strength of rubberized concrete with different rubber particles and mixing amount. Lastly, three modified methods were selected through the existing research results: Na OH modification, KH570 modification and compound modification.(2) The mixture properties of modified rubberized concrete were studied. The results show: the three modified rubberized concrete’s densities of concrete mixture are lower than the standard rubberized concrete’s and the slump constants are higher. Na OH modification reduced the density of rubberized concrete by 0.59 % and increased the slump constant by 24.4%, KH570 modification reduced by 3.1% and increased by 75.6% and compound modification reduced by 2.3% and increased by 70.7%.(3) The strength of modified rubberized concrete was studied. The results show: the strength of the Na OH modified rubberized concrete and the compound modified rubberized concrete is lower than the standard rubberized concrete, the strength of the KH570 modified rubberized concrete is equal to the standard rubberized concrete. The compressive strength, split strength and axial compressive strength of Na OH modified rubberized concrete were 94.9%, 98.8%, 95.1% of the standard rubberized concrete. Those of KH570 modified rubberized concrete and the compound modified rubberized concrete were 100.3%, 98.4%, 102.7% and 88.5%, 93.4%, 90.9%. It was considered by integrated analysis that modifications can improve the cohesiveness between rubber particles and cement paste, but weaken the compactness of rubberized concrete at the same time.(4) The stress-strain behavior of modified rubberized concrete was studied. The constitutive equations of modified rubberized concrete are fitted according to Guo-Zhenghai model and theoretical formulas and experimental results match each other well. Compared to the standard rubberized concrete, the peak strains of modified rubberized concrete become higher and the elastic modulus become lower. The peak strains of Na OH modified rubberized concrete, KH570 modified rubberized concrete and compound modified rubberized concrete were higher by 19.7%, 0.5% and 9.8%; the elastic modulus were lower by 13.5%, 3.3%, 10.2%.