| It has been successfully practiced using UTW in the overseas asphalt pavements, gettinggood performance and considerable economic benefit. According to the characteristics of urbanasphalt road in China, with the paper mainly introducing general issues related to structureprinciple, resurfacing design and future repairs, it makes a brief analysis on structure andmaterial properties of UTW. It includes theory of neutral axis and size effect of mini-slabs instructure principle of UTW. Introducing the concept of composite beam of mechanics ofmaterials into the theory of neutral axis, the calculation formulas of neutral axis were deduced.Based on the modified formula of temperature stress proposed by Bradbury(1938), it explainedthe improvement of temperature-warping stress due to the size effect of mini-slabs. To match thebond thin overlay, it interpreted that how the existing asphalt pavement can realize ultra-thinwhitetopping. Through summarizing the existing asphalt pavement condition assessment andcondition rankings, it discussed how to select appropriate concrete overlay solution.With the calculation of the finite element software, it analyzed the mechanicalcharacteristics of UTW in semi-rigid asphalt pavement. By means of research on axle-wheel typein design vehicle of urban road, then the paper determined the critical loading position of theUTW. According to city traffic loads and the temperature gradient effect, the variation ofdeflection and stress due to load and temperature were given in chart form. Based on the formulaof stress due to load in the center of slabs proposed by Westergaard (1927), the regressionformulas of maximum tension stress on the bottom of UTW layer and AC layer were preferablyspeculated, putting forward the influence coefficient of dummy joint that called K. Fatiguecracking due to stress was regarded as the design standard. Control indicators in design werefatigue cracking in the bottom of AC layer and fatigue fracture of comprehensive effect bycritical loading. To meet the demand of workability in pavement concrete, by using the sameaggregate gradation, it discussed that how the fibers content and fibers length influenced on theratio of compressive and flexural strength, properties of impact resistance and abrasion resistance.At the same time, the paper explored the improvement for flexural toughness of concrete withtwo different kinds of synthetic fiber mixed.This study has some innovative idea that can be used in the design guide of UTW andperformance study of fiber-reinforced concrete. |
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