Transverse Crack Patterns of Long-Term Field Asphalt Pavement Constructed with Semi-rigid Base.

Semi-rigid base is widely used in asphalt pavement construction, because they provide the potential to reduce rutting and lower pavement construction budgets. However, questions remain about the long-term performance of asphalt pavements with a semi-rigid base in terms of their propensity for transverse cracking. This study presents the results of a long-term field investigation of transverse cracking. The study collected 202 field cores extracted from 14 field test roads, and covers different pavement ages, traffic volumes, and recycled asphalt pavement (RAP) content across eastern China. Data regarding crack spacings, lengths, and propagation over time were obtained, while crack widths, depths, and patterns were analyzed using the field cores. The results show that crack spacings tend to be dense over the years until reaching an extreme value and the crack propagation can be clearly divided into three stages (0–4 years for initiation, 4–8 years for steady development, and a boost after 8 years) for the projects evaluated. The transverse crack can be categorized into four categories: surface-initiated cracking, reflective cracking with small area unpenetrated, reflective cracking, and thermal cracking. Surface-initiated cracking is the primary crack pattern found in asphalt pavements constructed with a semi-rigid base. A finite-element model was constructed, and the simulation results indicate that the surface-initiated crack tends to appear if the modulus of the base layer is higher, the asphalt top layer is more aged, the thickness above the base layer was thicker, or the cooling rate was faster. [ABSTRACT FROM AUTHOR]