| As a typical semi-rigid base material,the cement-stabilized macadam has many advantages such as large stiffness,high strength,good integrity and water stability.But,with the repeated actions of the load,the cement-stabilized macadam gradually exposed the shortcomings of poor anti cracking performance,and the problem of the road's service is also more and more serious because of the cement-stabilized macadam's reflection crack.In order to solve this problem,the domestic and foreign scholars have conducted a lot of research,such as the polyester fiber,polypropylene fiber,basalt fiber mixed into the cement-stabilized macadam to form the anti crack base.These studies have achieved certain results,but did not completely solve the problem of cement stabilized crushed stone base cracking,and promotion value is not high.Because polyvinyl alcohol(PVA)fiber has many advantages such as high strength,high modulus,corrosion resistance,acid and alkali resistance,non-toxic,non-pollution,etc,in this paper,the PVA fiber was applied to the cement-stabilized macadam for the first time.Through a comprehensive and systematic study of its mechanics and anti crack performance,it effectively solves the problem of cracking of cement stabilized crushed stone base.In this paper,the mixture ratio of PVA fiber cement stabilized crushed stone was designed,and the optimum water content,maximum dry density and optimum mix ratio of the mixture were obtained.By analyzing the compressive strength,compression modulus,splitting strength and flexural tensile strength,the mechanical properties of the mixture were studied.And through splitting strength,flexural tensile strength,compression modulus of resilience,dry shrinkage coefficient and temperature shrinkage coefficient to study the anti cracking performance of the mixture.Indoor test,cement dosage respectively by 3.2%,3.6% and 4.0%,fiber content were 0.6 kg/m~3,0.9 kg/m~3,1.2 kg/m~3,the fiber length respectively 12 mm,18mm,24 mm,30mm,and common cement stabilized crushed stone material mechanics and crack resistance of comparative analysis.The PVA fiber cement stabilized crushed stone material was applied to the actual project,and the influence of PVA fiber on the road service life and pavement thickness of pavement structure was analyzed through the observation of the test section.Combined with the results of laboratory tests and theoretical analysis,it is considered that the mixture ratio,maximum dry density and optimum water content of cement stabilized crushed stone materials are not affected by the incorporation of PVA fibers.The effect of PVA fiber on strengthening and toughening of cement stabilized crushed stone from two aspects: improving the internal structure of the mixture and changing the stress field.The mechanical properties of cement stabilized crushed stone were improved by the incorporation of PVA fiber,and the compressive strength,modulus of resilience,splitting strength and flexural tensile strength were improved in different degrees.PVA fiber can effectively improve the crack resistance of cement stabilized crushed stone,the drying shrinkage coefficient is obviously reduced,the temperatureshrinkage coefficient slightly decreases,the best fiber mixing scheme can make the cement stabilized crushed stone anti crack performance increased by 44.4%.PVA fiber cement stabilized crushed stones used in the actual project,the pavement structure layer,especially the thickness of the surface layer and the service life of the road has a certain impact.In this paper,the PVA fiber is used in cement stabilized crushed stone material for the first time,which can effectively solve the problem of cement stabilized crushed stone base crack,and provides a solution for the prevention and control of reflective cracking.Quantitative calculation of PVA fiber to improve the crack resistance of cement stabilized gravel,with great theoretical significance and practical guiding role. |
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