| At present,asphalt pavements continue to be more frequently damaged,and their overhaul period gets shorter and shorter.Meanwhile,asphalt mixtures incorporating fibers are becoming more extensively applied,which is because of its easy operation and obvious performance improvement.China has a wealth of bamboo resources,and as a result,has seen its usage across various fields and disciplines,however,large volumes of bamboo residue wastes are still constantly generated during bamboo processing.Natural bamboo fiber made from bamboo residue not only has high mechanical strength but also excellent resilience,as well as the advantage of natural renewability.In order to improve the pavement performance and expand the recycling prospect of waste bamboo residue,the performance of bamboo fiber asphalt and its mixture were studied.The main research contents were as follows:Firstly,in order to compare the differences of Ci bamboo fiber,Nan bamboo fiber and Lv bamboo fiber in macro/micro morphology,chemical composition and mechanical properties,the structural characteristics,physical and mechanical properties,water absorption and oil absorbency of three kinds of bamboo fibers were tested.The breaking strength of Lv bamboo fiber was as high as 9.47 cN/dtex in normal habit,but its lignin content was too low,so it was easy to agglomerate during the mixing process.On the other hand,the dispersion coefficient of N an bamboo fiber in asphalt was as high as 0.9212,but its larger brittleness caused the fiber to break easily during the process of mixing with stone.Meanwhile,although the breaking strength of Ci bamboo fiber was 9.24%lower than that of Lv bamboo fiber,it has better thermal stability and dispersion coefficient.Therefore,according to the results,Ci bamboo fiber has the best comprehensive properties,followed by Nan bamboo fiber,and Lv bamboo fiber in that order.Secondly,the influence of natural bamboo fiber type,fiber length and fiber content on the mechanical properties,rheological properties and anti-aging properties of natural bamboo fiber asphalt were analyzed in order to propose the optimal length and content range of bamboo fiber.The results showed that the nuclear and magnetic semaphore decreased after the bamboo fiber was added into the asphalt,that is,the viscosity of the asphalt increased,thereby significantly improving the mechanical and high-temperature properties of the asphalt,although the low-temperature rheological properties were weakened.In order to achieve the best mechanical properties,high and low temperature rheological properties of the natural bamboo fiber asphalt,the maximum allowable length and content of three kinds of natural bamboo fibers were initially recommended as follows:Ci bamboo fiber(9mm,2.0%),Nan bamboo fiber(6mm,2.0%),and Lv bamboo fiber(6mm,1.5%).Finally,the pavement performance of asphalt mixture containing bamboo fiber was tested,and then the recommended values of basic technical index of natural bamboo fiber for asphalt pavement were proposed(Table 4.17).The results showed that the pavement performance of the asphalt mixture was improved after the natural bamboo fiber was added,especially the rutting resistance at high temperature and the water stability.Furthermore,the best pavement performance of the mixture was observed when the length of Ci bamboo fiber was 7.25 mm and the content was 0.22%.After the test section was paved,the pavement structure and the economic benefits were all excellent.Moreover,the "Performance-price ratio" of the asphalt mixture containing Ci bamboo fiber was also the highest observed,although the initial investment has increased by 3.14%(about 8.5 yuan per ton of the mixture),however,the pavement performance of the mixture has been improved by 33.61%,and its total efficacy coefficient was 5.01%higher than that of polyester fiber.The application of natural bamboo fiber in asphalt pavement has significant social and economic benefits,and is therefore highly recommended for promotion in the road asphalt industry. |
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