Design of Sand-Cement Base Courses Using Fracture Mechanics Principles

Sand-cement base courses exhibit shrinkage and fatigue crack-ing. Both types of cracks tend to reflect through the asphaltictop layers. An analysis has been made to determine pavementlife, which is defmed as the number of cycles until cracks arevisible at the pavement surface, by taking into account fatiguecrack initiation, propagation and reflection as weU as propaga-tion and reflection of shrinkage cracks. Extensive use has beenmade of finite element analysis and fracture mechanics prin-ciples. It has been shown that weak cemented bases are morevulnerable for shrinkage cracking. Reflection of shrinkagecracks can however be overcome by means of sawing joints andby early overlaying the cemented base whit asphaltic surfacecourses.