Paper by SILFWERBRAND from ISCR 10th 2006 Brussels Belgium
In 1999, a 60 000 m2 large concrete pavement was completed in a Swedish harbour. The largest part of the area consisted of 200-210 mm thick plain jointed concrete pavement (PJCP) overlaying an old asphalt pavement. The design was based on certain prerequisite concerning traffic loads, i.e., axle loads and number of load repetitions, thermal loads due to specified thermal gradients, pavement system with prescribed layer sequence, layer thickness, material quality, bond conditions, and subgrade strength. The design was performed with the established Swedish concrete pavement design. Before five years of traffic, the concrete pavement showed extensive cracking in the most trafficked parts of the PJCP. Extensive crack mapping, FWD tests, coring, beam tests, microscopic analyses, and recalculations of load-carrying capacity have been conducted. The test results indicate that insufficient thickness and quality of the asphalt layer beneath the concrete, insufficient thickness and flexural strength of the concrete pavement, and possibly also improper joint sawing and curing all contributed to the cracking. The most important lessons learned deal with the existing asphalt pavement and the concrete quality. The assessment of the asphalt pavement has to be improved before placing an overlaying concrete pavement. A quality system for the concrete strength and thickness has to be installed.