Preparation Of Straw Fiber And Research On Road Performance Of Fiber Asphalt Mortar

As a big agricultural country,my country produces a huge amount of crop straw every year,but only a small part is effectively reused,resulting in serious waste of resources and environmental pollution.If the crop straw represented by corn straw and cotton straw can be processed into fibers and applied to the asphalt pavement,it can not only avoid the environmental pollution caused by the incineration and accumulation of the crop straw,realize the high-value utilization of the crop straw,but also give full play to the crop straw.The improvement effect of fiber on asphalt mortar improves the road performance of asphalt mixture and opens up a new way for the reuse of crop straw.In this paper,according to the composition structure of corn stalk and cotton stalk,corn stalk husk and cotton stalk main stem are selected as raw materials for preparing fibers,and they are mechanically crushed and screened to obtain corn stalk fiber and cotton stalk fiber.The structure,composition and basic properties are analyzed.On this basis,Na OH was used as modifier to modify corn stalk fiber and cotton stalk fiber with soaking concentration and soaking time as control indicators.The optimal modification process was optimized by two indexes of oil absorption and heat resistance.Secondly,the changes of chemical composition and micro structure of straw fiber before and after modification were studied by cold field emission scanning electron microscope and infrared spectrometer,and the modification was tested by p H value,oil absorption,heat resistance,ash content,adsorption and adhesion experiments.The basic properties of straw fibers before and after sex were studied and compared with lignin fibers.After that,the road performance of the straw fiber asphalt mortar with different dosages before and after modification was analyzed by the experiments of penetration,ductility,softening point,elastic recovery,and viscosity and toughness.The high and low temperature performance and fatigue performance of straw fiber asphalt mortar before and after modification were studied by linear amplitude scanning experiment,and the influence of fiber content and fiber type on asphalt mortar was analyzed,and compared with lignin fiber.Finally,the mechanism of modified straw fiber reinforced asphalt mortar was analyzed by characterizing its four components,functional groups and fiber dispersion characteristics.The experimental results show that when the diameter of the square-hole sieve is in the range of 0.3mm～1.18 mm,the length of the straw fiber can be controlled within 4mm;the basic indicators of the straw fiber modified by the Na OH concentration of 5% and the soaking time of 30 min are close to the lignin fiber..Modified straw fibers have better effects on improving the softening point,elastic recovery,shear resistance,high temperature rheological properties and fatigue properties of asphalt mortar,but have little adverse effect on low temperature rheological properties of asphalt mortar.When the content of modified straw fiber is 2%,the effect of comprehensively improving the performance of asphalt mortar is the best.The good oil absorption of the modified straw fibers reduces the light components in the asphalt,increases the asphaltenes,and improves the high temperature performance of the asphalt mortar.The infrared spectrum shows that the modified corn and cotton straw fibers are added to the asphalt,and no new functional groups are produced,which is a physical blend.The results of fluorescence microscopy showed that the modified corn and cotton stalk fibers were well dispersed in the asphalt mortar and could form a more stable three-dimensional network structure,thereby enhancing the stability of the asphalt mortar.It is feasible to apply the modified straw fiber to road engineering.At the same time,it provides a theoretical basis for realizing the industrialization of straw fiber,promoting the utilization of straw resources,and using it extensively.