Research On The Strength Formation Law And The Opening Traffic Timing Forecast Model Of Polymer Concrete

The research group has developed polymer concrete(PC)formed by using polyurethane instead of asphalt as a binder.It is a new type of green road paving material with excellent road performance and durability.However,its strength formation is affected by the interaction of temperature,humidity,catalyst dosage,and curing time,which leads to the unclear law of its strength growth,and it is difficult to determine the duration of curing and the timing of open traffic,which affects the promotion and use of this material.To this end,this paper studies the strength growth law of polymer concrete under different curing conditions,establishes a prediction model of the curing time to reach the final strength,and determines the strength requirements of polymer concrete that can be opened to traffic in combination with the indoor accelerated loading test.Based on this,a predictive model of open traffic timing for polymer concrete pavement is proposed,and the reliability of the predictive model is verified by combining physical engineering.Firstly,referring to the gradation of asphalt mixture AC-13,the polymer concrete PC-13 was prepared by the Marshall method,and the best rubber-to-stone ratio was determined to be7%.After testing,its various road performances met the design requirements.Secondly,according to the physical and mechanical properties of polymer concrete and the applicable climate environment,temperature(5℃,25℃,45℃),humidity(20%,50%,80%)and catalyst dosage(0.2%,0.4%,0.6%,0.8%,1.0%)are selected to conduct orthogonal experiments and determine 15 curing conditions for curing preservation.Tested the splitting tensile strength of polymer concrete under different curing conditions and times,analyzed the strength change law of polymer concrete,and found that different curing conditions only affect its strength growth rate,and does not change the ultimate mechanical strength.The change law of polymer concrete strength under different curing conditions with curing time is quadratic polynomial(R>0.95),the strength of the early stage increases rapidly,and the later stage of growth rate gradually slows down to stabilize.Through the use of multiple nonlinear regression analysis of the curing time under 15 curing conditions,a prediction model of the curing time for polymer concrete to reach the final strength was established.Then,in order to verify the reliability of the curing time prediction model,the polymer concrete was subjected to natural curing tests in different construction months to test the split tensile strength of polymer concrete under different curing conditions and times,and to analyze its strength change law.Substituting the average temperature and humidity during the natural curing period into the above-mentioned intensity growth prediction model,it is concluded that the model prediction time is slightly higher than the actual time required for natural health maintenance,but the difference is less than 10%,which verifies the accuracy of the model.Thirdly,based on the standard that the open traffic strength of polymer concrete should not only meet the technical requirements of road performance specified in the specification,but also have little effect on the growth of the later strength,the relationship between splitting tensile strength and dynamic stability,freeze-thaw splitting strength,low-temperature bending strain,fatigue performance and other road performance was studied,and the 2.12MPa of splitting tensile strength is the open traffic strength of polymer concrete was determined.In order to study the impact of the open traffic on the later strength growth at this intensity,an accelerated loading test was carried out on the polymer concrete that meets the requirements of the open traffic strength,and the simulated driving load was rolled to the end of the curing period.The cores were taken for the rolled and unrolled specimens,and the split tensile strength was tested and compared.It was obtained that the impact of open traffic on the later strength growth at this strength was less than 5%,which verified that the opening at this strength Reliability of traffic.Combining the determined open traffic intensity and the growth law of polymer concrete strength under constant temperature and humidity curing tests,a predictive model of open traffic timing is established.Finally,the polymer concrete paving entity project was built,and the split tensile strength was tested by coring the test roads that reached the open traffic time,which verified the engineering practicability of the polymer concrete open traffic timing prediction model.Continuous performance observations were carried out on the test roads to verify the reliability of the determined open traffic intensity engineering.