Effect Of Fiber Treatment On Properties Of Bamboo Fiber Asphalt And Asphalt Mixture

There are abundant bamboo resources in China.The application of bamboo residue fiber in road engineering is conducive to the development of environment-friendly traffic,which has practical significance.However,the inherent characteristics of bamboo fibers lead to their tendency to agglomerate within asphalt mixtures and form stress-weak zones,thus degrading the performance of asphalt mixtures.To further enhance the reinforcing effect of bamboo fiber on asphalt mixture,it is of great engineering value to study the effect of fiber pretreatment on bamboo fiber asphalt and asphalt mixture.To improve the dispersion uniformity of bamboo fiber in asphalt mixes,three commonly used pretreatment methods of plant fibers for road use are selected in this paper,and the bamboo fibers treated with different pretreatment methods are mixed into asphalt and asphalt mixes to analyze their effects on the performance of asphalt and asphalt mixes,and the best pretreatment method of bamboo fibers for road use is preferably selected.The main studies are as follows:First,the basic characteristics and microstructure of pretreated bamboo fibers were tested and analyzed.It was found that the microscopic morphology of heat-treated bamboo fibers changed the most and the fiber surface was the roughest and had the best oil absorption among the three pretreated fibers.A contact angle tester was used to analyze the interfacial properties of pretreated bamboo fibers and asphalt,in which the interfacial adhesion between the silane coupling agent-treated bamboo fibers and asphalt was the strongest,and also the least likely to peel under the action of water.Next,the effect of fiber pretreatment on the rheological properties of bamboo fiber asphalt was analyzed.The high and low-temperature rheological properties of pretreated bamboo fiber asphalt were tested by dynamic shear rheometer(DSR)and bending beam rheometer(BBR),and the black space diagram and damage characteristic curve based on viscoelastic mechanical damage model(VECD)of fiber asphalt mastic were analyzed to evaluate the cracking risk and fatigue characteristics of pretreated bamboo fiber asphalt mastic.The heat-treated bamboo fiber asphalt mastic had the highest fatigue life,which was56.3% higher at a 2.5% strain level compared to the untreated bamboo fiber asphalt mastic.Then,based on the precipitation leakage test,the relationship between different doses of bamboo fiber and fiber to asphalt uptake was established to evaluate the dispersion of bamboo fiber in asphalt mixture,and the agglomeration rate index was proposed to evaluate the dispersion of bamboo fiber in asphalt mixture.It was found that the agglomeration rate of heat-treated bamboo fiber asphalt mixture was the lowest,about 23% of the total amount incorporated.The road performance of the pretreated bamboo fiber asphalt mixture was tested,and the advantages and disadvantages of the three bamboo fiber pretreatment methods were evaluated based on the fiber asphalt adhesion,fiber asphalt mastic rheology,fiber dispersion efficiency,and the road performance of the pretreated bamboo fiber asphalt mixture,and the heat treatment was recommended as the pretreatment method for the road use of bamboo fiber.Viscoelastic mechanical response and fatigue life analysis were performed on the heat-treated bamboo fiber asphalt mixes.The greater dynamic modulus of the heat-treated bamboo fiber asphalt mixes and the heat-treated bamboo fiber asphalt mixes are more suitable for medium-temperature or low-frequency service environments.