As a repair method of concrete pavement, the overlay method is the most popular. In this case, the most serious factor that can reduce the life time and the peformance of the overlaid pavement is reflection crack caused by joints and cracks of the exi...
As a repair method of concrete pavement, the overlay method is the most popular. In this case, the most serious factor that can reduce the life time and the peformance of the overlaid pavement is reflection crack caused by joints and cracks of the existing pavement. In this study, a guide line for construction will be developed as a overlay method for domestic application through various laboratory test, similar to the site condition in order to select proper materials for the overlay that can well control the reflection crack in overlay. According to the result of lab tests, a field test will be constructed, considering the condition of an existing concrete pavement, economic and a plan to treat traffc. Some materials and methods corresponding to the properties of the test site will be suggested as materials and methods to control the reflection crack. Also, a mechanism of crack occurrenc? and growth will be analyzed and a program that can analyze such a mechanism will be developed to design the overlay into the numerical result. Major causes of reflection crack occurrence is due to the environmental factor, wheel load, and so on. This environmental factor is mostly related with temperature that gives an efect on shrinkage of concrete subgrade. When a concrete layer and overlaid layer pefectly stick to each other, shrinkage of existing slab causes crack that is occurred by vertical force to the crack in the overlay. Meanwhile, wheel load is loaded vertically on a pavement surface, especially, the differences in vertical deformation, are occurred by the movement of the loading on the crack surface, are very important. This passing wheel load causes shear stress and bending moment, at the same time, in the surface. Consequently, shear stress and bending moment cause the reflection crack.