Premature distress mitigation in continuously reinforced concrete pavements
Zusammenfassung
Field investigations conducted for the performance evaluation of Continuously Reinforced Concrete Pavements (CRCP) in Texas revealed that a large number of distresses occurred due to non-structural issues. About 40% of the total distresses were found to be at transverse construction and repair joints in CRCP. These distresses were occurring in pavements during the first 10-15 years after construction and are referred as “Premature” distresses occurring due to construction or material related issues.
Several mechanisms were postulated to be responsible for occurrence of different premature distress types based on field conditions. The use of additional steel in the form of tie-bars, manual placement and insufficient consolidation and debonding between the steel and concrete were considered as scenarios leading to distresses near the transverse construction joints (TCJ). The effect of additional lane construction on the concrete at the junction of the transverse and longitudinal construction joints was also evaluated. Test sections were constructed and the behavior of steel, concrete and slab movements with change in temperature at the transverse construction joint were evaluated and monitored using steel and concrete strain gages, displacement transducers and data acquisition systems. The effect of the use of coarse aggregate type and time of concrete placement on occurrence of Y-shaped and narrow transverse cracks in CRCP were also studied.
The longitudinal reinforcement and tie-bars at TCJ were found to be behaving differently with temperature changes. At higher temperature, the additional tie-bars were found to be in extreme compression. Presence of voids in the concrete near the TCJ established insufficient concrete consolidation at the TCJ. Removal of additional tie-bars during construction at TCJ was suggested along with guidelines to evaluate recommendations in pilot trial sections.