Research And Application On Impregnated Geotextile Technology In The Overlay Of Pavement

Geotextiles and fiberglass fabrics are usually used as the anti-reflective cracking layer of "white plus black" and "white plus white" pavement in major repair works of national and provincial highways.Geotextiles are mainly pasted by hot asphalt or emulsified asphalt.The original cement concrete pavement or the underlying layer is uneven,so the geotextile is difficult to bond with the lower layer.Besides,the transport wheel and paver crawler will pull the geotextile or grille to destroy the integrity between the layers.So when the geotextile is impregnated with cementitious material which has strong permeability,the cementitious material can be filled into the fabric and fill the lower layer,which leads to a complete combination of the impregnated layer and the underlayer.If the impregnated synthetic materials are applied to the transition layer of the composite pavement structure,the anti-reflective cracks and interlayer bonding properties of the newly added pavement will be improved.This is of great significance for improving the road performance of the overlay pavement and prolonging the life of the road.This paper firstly uses the fracture mechanics theory and the Abaqus finite element modeling to explore the causes and the expansion mechanism of the reflective cracks in the composite pavement structure.On the basis of the above,the development of cement and asphalt impregnated cementitious materials,such as modified cement mortar and modified emulsified asphalt,is developed.The modified effect of modified cement mortar is mainly evaluated by the conventional performance indexes of cement materials such as compressive strength,flexural strength and adhesion,while modified emulsified asphalt is mainly evaluated by its conventional performance index such as penetration,ductility,softening point and viscosity of evaporation residue.Then,we determined the amount of two kinds of gelatin modifiers by several relevant tests.The results show that the flexural strength and uniaxial compressive strength of modified cement mortar are the best when the amount of nano SiO2 is 2%,the amount of expansive agent is 8.5%,the amount of rubber powder is 0.9%,and the amount of active powder is 3%.When the dosage of SBS latex is determined at 5%,the performance indexes of modified emulsified asphalt are more balanced and the modification effect is good.Using the modified cementitious materials which was previously prepared to impregnate the corresponding geotextiles.Then evaluating the mechanical properties of the impregnated compound preliminarily through the tensile strength test,the test results show that the tensile properties of the geotextiles after impregnated with modified cement mortar and modified emulsified asphalt have been greatly improved.Later,used the scanning electron microscope and the fluorescence electron microscope to observe the modified cement mortar and modified asphalt impregnated geotextiles,probing into the mechanism of its impregnation,and analyzing the change of mechanical properties from microcosmic angle.Finally,The subject apply impregnated geotextiles to built a pilot transition layer of one particular road relying on the demonstration project,and study the construction technology of impregnation and the quality control points in the construction process.All the completed work not only test its road performance,but also provide an accurate reference for the maintenance technology of the old cement concrete pavement in the future.