Study On Surface Modification Of Bagasse Fibers And Properties Of Asphalt Mortar With Bagasse Fibers

Bagasse is the main by-product of the sugar industry of sugarcane,but only a small part of bagasse is reused,causing serious waste of resources and environmental pollution.The application of bagasse fibers obtained by processing in asphalt pavement can not only realize the high value utilization of bagasse,but also play a role in improving the performance of asphalt mortar.And this paper can be used as a reference for the utilization of bagasse.In this paper,bagasse fibers were taken as the research object.Firstly,the microstructure,composition and basic properties of bagasse fibers were analyzed.On this basis,hydrochloric acid,sodium hydroxide and sodium chlorite were used as modifiers to modify bagasse fibers,including single modification,binary composite modification and ternary composite modification.Then,the modification methods of bagasse fibers were optimized through the indexes of oil absorption,heat resistance and dispersion.Secondly,the modern material analysis technologies were adopted to explore the changes of chemical composition,thermal stability,crystallinity,micro morphology and mechanical properties of bagasse fibers before and after modification,and the mechanisms of surface modification were discussed.Finally,the cone penetration test,dynamic shear rheological test and bending beam rheological test were used to evaluate the properties of asphalt mortar with bagasse fibers before and after modification.The influences of the the modification methods and content of bagasse fibers on the properties of asphalt mortar were analyzed,and the asphalt mortar with lignin fibers was used as a comparison.The results show that the microstructure of bagasse fiber is multilayered,and its cell fiber is a kind of lumen structure wrapped by different layers of cell walls.The main components of bagasse fiber are cellulose,lignin and hemicellulose.The heat resistance and oil absorption of bagasse fibers were improved by five chemical modification methods.After binary and ternary modification,most of the impurities on the surface of bagasse fibers were removed,the diameter of fibers were decreased,and the ratio of length to diameter of fibers were increased,which significantly improved the oil absorption of these two fibers.Compared with the original bagasse fibers,the oil absorption ratio of the binary and ternary composite modified fibers increased by 60% and 69%,respectively.The mechanical properties of bagasse fibers before and after modification changed significantly.The tensile strength of the ternary composite modified fibers was the largest,which was four times that of the origin fibers.The mechanical properties of the modified fibers are related to the cellulose content,tensile cross-section area and crystallinity.Fibers can adsorb the light components of asphalt to form the transition zone at the interface,which results in the recombination of asphalt components in the interface bonding zone and the improvement of interfacial adhesion between fibers and asphalt.Among the five kinds of modified fibers,the ternary composite modified fibers has the best effect on the improvement of the shear strength and high temperature rheological properties of asphalt mortar,and has little influence on the low temperature rheological properties of asphalt mortar,which is close to that of lignin fiber.When the content of fibers is 3%,it can effectively exert its reinforcing effect,significantly improve the high-temperature deformation resistance of asphalt mortar,at the same time,it has little influence on the creep stiffness modulus and creep rate of asphalt.When the content is more than 3%,the fibers are difficult to disperse in asphalt,which weakens the effect of fibers on high temperature rheological property,and has a negative effect on low temperature rheological property of asphalt.The ternary composite modified fibers are obtained from bagasse fibers modified by sodium hydroxide,sodium chlorite and hydrochloric acid in turn.The high temperature performance of asphalt mortar can be improved obviously when the fibers content is 3%.It is feasible to apply bagasse fibers to asphalt pavement engineering after ternary compound modification,and at the same time,it widens the way for the utilization of bagasse.