Use of Backcalculated Falling Weight Deflectometer Modulus for Detecting Foundation Problems Caused by Rubblization of Concrete Pavements

In 1998, two rubblized-pavement sections of Interstate 10 in Florida failed prematurely and showed severe rutting. During and after rubblization, large amount of water was observed flowing from edge drains next to the failed areas. Falling weight deflectometer measurements were taken immediately after rubblization, as well as one month and three months later. The backcalculated base and subgrade moduli showed softened sections immediately after rubblization, with a recovery period in excess of one month. A detailed study of the conditions leading to failure showed that the failure of the sections was likely due to the development of positive pore pressures in the base and subgrade during rubblization. These positive pore pressures lead to poor compaction after rubblization and severe rutting with localized potholes immediately after the first holiday traffic. Further analysis of the backcalculated moduli also showed that the problem was compounded by the absence of a tack-coat between the asphalt concrete and the rubblized layer, leading to poor load transfer to the lower layers. For the covering abstract see ITRD E118503.