Influence of Modified Wheat Straw on Performance of Cement Stabilized Crushed Stone
In order to study the effect of modified wheat straw on the performance of cement stabilized crushed stone,the surface modification of wheat straw was carried out by using different concentrations of NaOH solution,and the effects of NaOH solution concentration and modification time on the quality of straw were analysed.The modified straw fibers were incorporated into cement stabilized aggregates,and the optimal fiber ratios were obtained through the unconfined compressive strength test and splitting strength test.The dry shrinkage test and freeze-thaw test were carried out under the optimal fiber ratios,combined with the environmental scanning electron microscope(ESEM)test,to observe the microscopic changes of wheat straw before and after modification,as well as the role of straw fibers in the cement stabilized aggregates.The results show that:the mass loss rate of wheat straw is higher when wheat straw is modified by 3.5％(mass fraction)NaOH solution for 12 h,which is conducive to reducing the retardation effect on cement;the mechanical properties of straw fiber in cement stabilized crushed stone are significantly enhanced,and the strength is the highest when the fiber length is 20 mm and the dosage is 0.15％(mass fraction),and with the prolongation of the curing age,the mechanical properties of cement stabilized drushed stone are continuously improved.Compared with ordinary cement stabilized crushed stone,the dry shrinkage performance and frost resistance of straw fiber cement stabilized crushed stone are significantly improved.ESEM analysis shows that the modified wheat straw can improve the adhesion with the matrix,prevent or delay the generation and development of cracks,and improve the mechanical properties and anti-cracking properties of cement stabilized crushed stone.
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