Preparation And Performance Of Bamboo Fibers Reinforced Asphalt Concrete

High-quality materials play important role for the long-term service of road pavement.Fiber addition can prevent formation of pavement cracks of asphalt concrete and avoid early pavement diseases caused by pits and flaking.Bamboo fiber can be used as a novel reinforcement for asphalt concrete because of its high tensile strength,good thermal stability,rough surface texture,environmentally friendly,and low cost during its extraction and process.In this paper,bamboo fibers reinforced asphalt concrete was prepared by adding different length and amount of fibers.Due to the difference in the chemical characteristics of bamboo fiber and asphalt,the interfacial bonding between bamboo fibers and asphalt matrix is weak,leading the poor mechanical properties of asphalt concrete and limitation of its application in engineering.Thus the bamboo fibers were treated by melamine-formaldehyde copolymer to improve the interfacial adhesion between fibers and asphalt matrix.By using Fourier Transform Infrared Spectroscopy(FTIR),X-ray Photoelectron Spectroscopy(XPS),and Nuclear Magnetic Resonance(NMR)techniques,the chemical properties of fiber surfaces before and after modification were characterized.The performance of bamboo fiber reinforced asphalt concrete in crack resistance was investigated by indirect static tensile test and direct tensile test.In addition,the bamboo fiber asphalt concrete was further evaluated with mechanical properties,road performance and microstructure,which may provide theoretical basis and technical guidance for its application in road engineering.The conclusions are given as follows:(1)The surface chemistry analysis of bamboo fibers showed that the surface chemistry of bamboo fibers was changed after the modification with melamine-formaldehyde copolymer,resulting in improvement of interfacial adhesion between bamboo fibers and asphalt matrix.SEM images indicated that the fibers were well-coated by asphalt,such that stress can be easily transferred from the fibers to the asphalt matrices when the asphalt was loaded.(2)After the modification of melamine-formaldehyde copolymer for bamboo fibers,the tensile modulus and flexural modulus,rigidity,and stability value of the resulting bamboo fiber reinforced asphalt concrete are significantly improved.The asphalt concrete reinforced with 0.2 wt%of bamboo fibers of 2 cm in length has the highest stability value.The modified bamboo fibers show a desirable dispersion in asphalt matrices.(3)The addition of fibers improves the tensile strength of asphalt concrete.After the surface modification of bamboo fibers,the static indirect tensile strength of asphalt concrete is significantly improved.The direct tensile strength and tensile strain energy increase as well.(4)The asphalt mixture rutting test illustrated that the dynamic stability of bamboo fiber reinforced asphalt concrete is improved,compared with that without fiber addition.The high temperature stability achieved its optimum outcome when 0.2 wt%bamboo fibers were added.The ability of modified bamboo fiber reinforced asphalt concrete to resist low temperature damage and water damage was both enhanced after fibers modification.In summary,the performance of bamboo fibers reinforced asphalt concrete for using in road engineering was improved after fibers modification.