| Cement concrete is widely used in pavement structure due to its high strength,good stability and low maintenance cost.It is not only applied in high-grade highway,but also an important form of low grade road.However,due to the vast territory,the complex natural environment and the effect of traffic load,the disease of cement concrete pavement is becoming more and more serious.There are many diseases such as denudation,cracking,pits,and broken boards caused by uneven settlement of subgrade and subgrade.Especially in the low grade highways,fewer traffic load,axle load is small,the early diseases of cement concrete pavement are generally focused on the surface,such as pits and plate angle fracture,micro cracks,and the base and subgrade did not appear serious damage,if the renovation overhaul,consider the economic efficiency,is not suitable for.At this time,thin layer paving method should be adopted for pavement maintenance,so that it can not only repair pavement disease,improve the service life of the pavement,but also reduce the budget and achieve the desired effect.In order to improve the characteristics of concrete fracture and the bonding effect of pavement layers between the poor,this paper adopts thin basalt fiber cement concrete(Basalt Fiber Reinforce Concrete,referred to as BFRC)were low grade cement concrete pavement overlay design,because a large amount of research at home and abroad have proved that BFRC has tensile properties and durability bending more better than ordinary cement concrete pavement,can prolong life,reduce the rigid fracture.The surface treatment of old cement boards has a great influence on the overall pavement structure when thin layer is applied.Therefore,the following research is done for basalt fiber cement concrete overlay pavement.1.The mechanical properties test of BFRC material,including compressive strength,flexural strength and splitting tensile strength,was carried out.The best BFRC ratio of mechanical properties was obtained by changing the amount of basalt fiber,and finally the content of basalt fiber was 2kg/m3.2.Made of basalt fiber reinforced concrete overlay with the original cement concrete interlaminar shear test,using different layer processing methods,namely:do not do any processing layer,keep the surface smooth;the layer between the groove groove processing;and the user interface of the agent layer,the interlayer bonding more closely.Based on the shear test,the relationship between vertical stress and shear stress under three kinds of interlayer treatment is obtained.According to Kulun Moore's theory,the friction coefficients of different interlaminar treatments are 0.2169?0.4486 and 0.6582 respectively.3.According to?The Standard of Ccement Concrete Pavement Design for Highway?JTG D40 2011 in the design of overlay requirements,depending on the cement concrete pavement overlay structure for BFRC double plate calculation model of double plate pavement structure by using finite element software ABAQUS analysis and specification and double plate stress solutions were compared,obtained the load is calculated by the finite element model of stress and the analytic solution of the relative error is 3.07%,the temperature relative errors for the stress and the analytical solution is 4.72%,proving the reliability of the model.On this basis,the static and static analysis of the BFRC overlay model of cement concrete pavement is carried out.(1)The friction coefficient of different layer is obtained by testing with the original shop between two plates,was analyzed by ABAQUS finite element numerical load on different position,get the constraints in the direction of traffic conditions,when the load in the foot,load the overlay and the original cement slab produced by stress and deflection.The deflection value is almost 2 times the load in the.(2)To overlay thickness between 4?7cm,calculate the overlay and the original cement concrete shear stress,and shear test in 0.7MPa vertical stress under shear strength contrast,found no numerical processing between the middle layer shear stress value of shear strength is less than from the test,the interlayer treatment should not be used.(3)The load stress under dynamic and static load is simulated and analyzed.It is found that the shear stress values of the two action modes are relatively small due to the shorter action time of each dynamic load,but compared with the static load,the stress state of the whole pavement structure evolves to an adverse direction under dynamic load.(4)The influence of different structural parameters on the stress of pavement structure is analyzed.With the increase of the thickness of the old cement slab and the elastic modulus of the base and soil foundation,the load stress of the original cement concrete slab decreases.(5)Combined with the standard cement board has no limit of fatigue fracture formula,the effect of friction coefficient calculation of layer on pavement fatigue life,fatigue life and groove design that the interface is not any treatment,interlayer between groove processing and inter agent treatment conditions were 425420 times,725086 times,1644417 time.To sum up,during the repair of low grade cement concrete pavement,thin layer basalt fiber cement concrete can be used to design the overlay.The thickness is selected from 4 to 7cm. |
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