The Effect Analysis And Experimental Study On Asphalt Concrete Reinforced By Glass Fiber

At present,it is an important research direction to add fiber materials to the Asphalt Mixture in the research of the road construction materials . Glass fiber reinfored asphalt concrete is adding glass fiber to the asphalt concrete , and its construction technique is similar to ordinary asphalt concrete. Because of the wide source of the glass fiber in China ,its low cost ,and high elastic modulus,it is often used as a reinforcement of composite materials.On the other hand, preliminary experimental study declares that, glass fiber asphalt concrete has improved its high temperature stability and low temperature anti-cracking performance and increases the carrying capacity of asphalt pavement and anti-deformation capacity. This article is to study the effect of the glass fiber reinforced asphalt concrete, through theoretical and experimental analysis of glass fiber reinforced asphalt concrete. Moreover,this paper studys the effect factors of glass fiber enhanced asphalt concrete by changing the length of glass fiber.Chapt II is the theoretical basis of this article. It analyses the role of strength and bridge of the glass fiber through the principle of the composite material to enhance the mechanical strength and transmission of shear stress . Because the elastic modulusthe of glass fibers is more than three times than the ordinary asphalt concrete's. The glass fibers and asphalt concrete work together under the load.When the interface strength is enough ,the glass fibers and asphalt concrete have the same strain. Therefore, the stress of glass fiber is greater than the stress of asphalt concrete.The two kinds of stress are equal to the outside stess. so , It is equivalent to a reduction of stress in the asphalt concrete after adding glass fiber into it. Because the strain of the asphalt concrete is less than the glass fiber's, when the ultimate strain of asphalt concrete is reached, the damage load of the glass fiber asphalt concrete is greater than the ordinary asphalt concrete's.The stress between glass fibers and asphalt concrete is through the the adhesive force (shear stress) to transfer.When the interface strength is suitable ,the strain of asphalt concrete produced under the load.At the beginning of deformation, the matrix and glass fiber have a dislocation .Then the adhesive force will prevent this dislocation . The stress transfers from the matrix to the glass fibers through the interface shear stress between the matrix and glass fibers .When the strain of the glass fiber and the strain of asphalt concrete are equal, the relative dislocation is zero.There will be no interface shear stress . At this point the stress of the glass fibers reach its maximum and remain the same level.In achieve to reach the maximum stess ,glass fibers need a load-transfer length. When the glass fiber length is greater than the length of the load-transfer, the glass fiber will play the role of the basic enhance effect.The longer the length of the glass fiber is,the higher utilization of the fiber length is.Because the load-transfer length is definite,and the stress.of load-transfer lengthin the fiber is less than the maximum stress .Therefore the length of load-transfer length is called ineffective length. The longer the length of the fiber is, is , the shorter the relatively length ineffective length is, the longer the relative effective length is,the higher the utilization length of fiber is, the more obvious the effect of the fiber enhancement. Moreover,the best asphalt content of the glass fiber asphalt concrete is larger than the ordinary asphalt concrete's.Because when the fiber is added,the fiber is equivalent to the filler. The bitumen saturation increases, the relative proportions of the structure asphalt increases, the interface intensity between asphalt and mineral aggregate will increase .The interface strength between glass fibers and the asphalt is produced through adhesive force of the asphalt. To enhance the strength of its interface, but also to disperse glass fibers, glass fiber sizing is often coated . The sizing will help fiber glass and asphaltto merge better ,to increase the interfacial bond strength and ensure that the stress between glass fibers and asphalt concrete is transfered through shear stress sucessfully.Chapter III is the further study of fiber glass asphalt concrete design . In order to enhance the effect of asphalt concrete,this chapter studies the effect factors We use the same glass fiber content, the same asphalt concrete Gradation and the same asphalt content.But we change the length of glass fiber ( 6mm, 12mm).Then we test the Marshall stability ,Marshall flow values on Marshall specimen,dynamic stability and rut depth on rutting specimen. This paper improves the the manner of addition of glass fiber .The manner is that scatter the glass fiber in asphalt which is poured inthe mixing pot already.In one hand ,the glass fiber is fully coverd by the asphalt,in the other hand,it helps the glass fiber separate better and format a single silk fiber easier. When the rutting sample is made and tested ,it give some instruction about depth of rutting indicator,coefficient,holding time.It analyzes the he variability in porosity coefficient of the two kinds different length to measure the uniformity of the sample.We find out that the uniformity of 12mm long sample is worse than 6mm's.But not too worse. So we get the conclution that the uniformity can not affect the long glass fiber asphalt concrete role.The result of the experiment shows that: glss fiber of 12mm long asphalt concrete has higer Marshall stability and flow values than glss fiber of 6mm long asphalt concrete. But less rutting depth .It indicates that the effect of 12mm is better than the 6mm's.Because the effective use of the fiber length of the longer fiber is higher than the shorter fiber's.The average of strength of the longer glass fiber is bigger. It formats more stable network structure space .So it bonds mineral aggregate more effectively and the load-bearing capacity and anti-deformation capacity is stronger and greater.Chapter IV uses the theory of Chapter II and the experiments in Chapter IIIt to analyze the effect of the glass fiber on asphalt concrete . The article points out that the effects of glass fiber is influenced by many factors.The length of glass fiber is one . After adding glass fibers, the carrying capacity and anti-deformation capacity of asphalt concrete is improved. And longer glass fiber asphalt concrete has better carrying capacity and anti-deformation capacity.Therefore, this article proposed the co-ordination of long glass fiber design, thus reducing the amount of mixing glass fibers, while reducing the optimum asphalt content, this can reduce the project cost but enhanced effects are not reduced. Chapter V is the final chapter of this article.It is the summary of the full text and puts forward in the next step of work to continue the study and research.