Study On The Performance Of Large Pore Polymer Mixtures

Large pore polymer mixtures is a key research direction of new materials for pavement paving in sponge city constructions,because it not only have the characteristics of high strength,mix and spread at room temperature,energy saving and environmental protection but also can effectively discharge the road surface water.However,the research and application of this material is still less.So in this paper,large pore polymer mixtures will be studied in mix design,road performance and anti-aging properties through the indoor test,and the data will be as the reference in the further research and application.Firstly,the suitable polymer adhesive in road pavement was selected according to the classification and the properties of the polymer adhesive.And the empirical formula of OGFC asphalt mixtures and the coating condition of adhesive for aggregates was combined to preliminarily determine the dosage of polymer adhesive.A mix design method based on performance balance and target void ratio was put forward by testing the change of volume index and performance indicators in this dosage range,and the optimum dosage of adhesive was 5.9%.In addition,the film thickness of the large pore polymer mixtures was 12μm~18μm,which was recommended to use a higher film thickness.The optimum ratio of the OGFC asphalt mixtures used for comparison was 4.9%.Secondly,the road performance of large pore polymer mixtures were studied.It was found that the high temperature performance of the large pore polymer mixtures was obviously superior to that of OGFC asphalt mixtures with the same grade,and its dynamic stability exceeded the limit.The low temperature performance of the large pore polymer mixtures was excellent.The strain energy density is 1.7 times that of OGFC asphalt mixtures,and the low temperature failure strain is 10.4 times that of OGFC asphalt mixtures.Under the same void fraction,the anti-skid performance of the large pore polymer mixtures was comparable to that of OGFC asphalt mixtures,and the anti-slip coefficient is greater than 60.And the water permeable performance was not much different from that of OGFC asphalt mixtures,which was about 3000ml/min.For the water stability,the modified water stability test were proposed because the current test methods of the asphalt mixtures were not suitable for the large pore polymer mixtures,and the results showed that the water stability of the large pore polymer mixtures was similar to that of OGFC asphalt mixtures,and both were poor.Finally,in terms of anti-aging performance,the effects of UV-irradiation aging and thermal oxygen aging on material properties of Beijing area within a year were simulated by artificial aging.The aging time was determined by the equal principle of the indoor and outdoor ultraviolet(UV)radiation amount,four indoor aging time of 0h,170 h,341h and 511 h were selected,and the corresponding outdoor UV-irradiation aging time were 0 months,4 months,8 months and 12 months.The methods of modified water stability test and four-point bending fatigue life test were used as the evaluation method.For the test of water stability,we compared the dry split strength,residual splitting strength and residual splitting strength ratio of the two kinds of mixtures,and the results showed that the change rate of dry split strength of the two kinds of mixtures was both about 10% after aging 511 h.However,the large pore polymer mixtures decreased by 39% in residual splitting strength and 11.4% in the residual splitting strength ratio after aging,more than 15% and 2.1% of that OGFC asphalt mixtures.It showed that the adhesion between the adhesive and aggregates was reduced to a certain extent in the drying state,but it was not significant.However,the hydrolysis could significantly reduce the adhesion between the adhesive and aggregates in the large pore polymer mixtures.For the test of fatigue resistance,we compared the fatigue life frequency,initial bending stiffness modulus and bending stiffness modulus decay rate,and the results showed that the fatigue resistance performance of large pore polymer mixtures was far better than that of OGFC asphalt mixtures,when the fatigue life frequency reached 1 million times before and after aging,and the decline of bending stiffness modulus was far less than 50%.However,the fatigue life of OGFC asphalt mixtures was 31000-57000 times,after aging 511 h,the fatigue life was reduced by 45%.The initial bending stiffness modulus of large pore polymer mixtures decreased with the aging time,which was the opposite of OGFC asphalt mixtures.It was because that the long chain molecules of the polymer materials were cut into short chain molecules and free radicals,which resulted in a reduction in the modulus.And the numerical value was all lower than OGFC asphalt mixtures.The bending stiffness modulus decay rate of large pore polymer mixtures increased after aging 170 h,by the end of aging 511 h,which was increased from 0.9% to 3.2%,but it was still very small.As can be seen from the change of initial bending stiffness modulus and the bending stiffness modulus decay rate,the effect of aging on OGFC asphalt mixtures is more significant.It could be found that the opposite conclusion had been reached by the two experimental methods.The effect of aging on the water stability of large pore polymer mixtures was higher than that of OGFC asphalt mixtures,but the fatigue resistance performance was the opposite.And it was concluded that the existence of hydrolysis was the root cause.