Experimental Study On Indexes Of High Dosage Of Rubber Powder Modified Asphalt And Performance Of Asphalt Mixture

Based on the science and technology research project of universities and colleges in Hebei Province,this paper conducts experimental research on the index of high-volume waste rubber powder modified asphalt and the performance of the mixture.The modification mechanism of waste rubber powder modified asphalt was studied by means of infrared spectroscopy,thermogravimetric analysis and scanning electron microscope.The experimental method was used to explore the effects of the amount of waste rubber powder on the high temperature performance,low temperature performance,and viscoelastic properties of rubber powder modified asphalt.Three different waste rubber powder modified asphalt mixtures were selected for their mix ratio,optimal oil-stone ratio,and road performance,and ANSYS finite element simulation was used to analyze the characteristics of a typical pavement structure.Depending on the actual project,reasonable suggestions are made for the production and transportation of the mixture.The main research conclusions are as follows:1.The thermogravimetric analysis was used to investigate the weight loss of modified asphalt with rubber powder and different amounts of waste rubber powder under high temperature conditions,and the chemical composition of waste rubber powder modified asphalt treated at different times was analyzed with infrared spectroscopy.It is concluded that the main reason for the modification of asphalt is the oxidation decomposition reaction between the waste rubber powder and the asphalt.2.Through the modified asphalt index test,the performance of the modified asphalt with different amounts of waste rubber powder was analyzed.The test proved that the addition of waste rubber powder significantly improved the high and low temperature performance and viscoelastic properties of the modified asphalt.With the help of SEM electron microscopy,the distribution of the waste rubber powder in the modified asphalt,and proposed the relationship between the effective rubber powder content and the content of the waste rubber powder.3.The best gradation and oil-stone ratio of SMA13,20%-ARHM20 and 30%-ARHM20 mixtures were obtained through laboratory tests,and their high and low temperature performance and durability performance were tested.The results show that the comparison results of the high temperature performance of the three modified asphalt mixtures selected in this paper are: the dynamic stability of the dense graded mixture is 8045.3 times / mm,which is 22% and 9% higher than 30%-ARHM20 and 20%-ARHM20 respectively;The performance comparison is that the flexural tensile strength of the modified asphalt mixture with 30% waste rubber powder content is 13.26 Mpa,which is 13.8% and 4.2% higher than SMA13 and 20%-ARHM20,respectively.The results of anti-freeze-thaw splitting are as follows: the 30%-ARHM20 mixture at break grade has the best water damage resistance,the tensile strength ratio of freeze-thaw splitting is 95%,and the 20%-ARHM20 mixture at break grade is similar.The freeze-thaw splitting strength of the two is 11.9% and 10.8% higher than that of the SMA13 dense-graded asphalt mixture,respectively.4.Using ANSYS software to simulate driving loads under different pavement structures,the results show that using ANSYS finite element simulation can more accurately simulate the stress situation of the pavement.The stress distribution of the pavement structure layer gradually decreases with the increase of the pavement depth.The smaller the modulus of different structural layers,the faster the stress decreases;and it will occur at the contact surface of different materials.The sudden increase in stress should be strictly controlled to reduce road damage.5.Relying on the test section of the Handan section of the Taihang Mountain Expressway,ARHM20 graded waste rubber powder modified asphalt mixture is used to pave the middle course.The production,transportation,paving,rolling and field verification of ARHM20 mixture are summarized and analyzed It is proposed that all stages should be strictly controlled in accordance with the construction standards,and other necessary measures should be taken to minimize the impact on the performance of the modified asphalt mixture.