Field Effects of Water Pumping Beneath Concrete Pavement Slabs

Water pumping beneath concrete pavement slabs is considered to be a major cause of pavement failure. The objectives of this work are to determine typical water pressures and velocities during pumping in the field as well as the effects of pressure, velocity, and thermal movement on erosion beneath slabs. The location of the water pumping is between the bottom of the concrete slab and the subbase. Field tests indicate that vehicle traffic produces high pressures beneath the second slab and suction pressures beneath the first, which induces water velocities in the opposite direction of vehicle motion. Field tests on Florida's Interstate 10 reveal pressure differences as high as 70 kPa, which produce velocities up to 0.9 m/s in the opposite direction of vehicle motion. Water pumping is more severe at the corner of the second slab and during upward thermal curling. Water movement may not be sufficient to cause subbase erosion based on this limited field data. The daily expansion‐contraction cycle is shown to produce enough loose material to induce approximately 0.5 mm of faulting annually.