Rational Use of Terminal Anchorages in Portland Cement Concrete Pavements
It has long been stated that Portland cement concrete (PCC) pavements can grow and push bridges, resulting in damage to bridge structures. To protect bridge structures from damages due to the expansion of PCC pavements, three terminal systems are currently used in Texas: anchor lug (AL), wide-flange (WF), and expansion joint (EJ) systems. However, the effectiveness of these three systems has not been fully evaluated. This study investigated the parameters affecting the movements of continuously reinforced concrete pavement (CRCP) due to temperature variations near bridge terminal areas, whether thermal expansion of CRCP causes damage to bridge structures, and if it does, which terminal type is the most cost-effective. Field evaluations revealed that subbase friction plays an important role, and the movement of CRCP due to temperature variations was not excessive if the subbase friction is adequate and may not cause damage to the bridge structures. Most of the distresses near the bridge terminal areas were due to volume changes or instability in the embankment materials. The end movement of CRCP could be accommodated by a simple EJ system if there is adequate subbase friction. The benefits of WF and AL systems are doubtful considering their higher initial construction costs compared with that of a simple EJ system. On the other hand, it should be noted that in a few CRCP projects, observations were made of CRCP expanding beyond the thermal expansion limits, implying that there are other expansion mechanisms than thermal expansions. The investigation of CRCP expansions due to factors other than thermal volume changes was out of the scope of this project. Simple structural analysis showed that if CRCP expands beyond thermal expansion limits, it is practically impossible to restrain the slab expansions with known methods including the AL system.