Experimental mechanics of crack width in full-scale sections of continuously reinforced concrete pavements.

摘要

Continuously reinforced concrete pavements have numerous transverse cracks that occur naturally at variable spacing. These cracks do not affect the performance of the structure unless they widen and result in a loss of load transfer efficiency. The capacity to transfer vertical loads across a crack depends on a series of factors of which crack width is the most important, and the focus of this research. Five pavement sections were built and loaded under accelerated traffic conditions at the ATREL full-scale testing facility. The opening and closing of cracks was measured at several transverse cracks, along with vertical deflections, transverse strains at the top of the slab, and pavement internal temperature. Two procedures were developed to determine crack width from the measurement of crack closing. They use the deformation caused by the vertical load and differ from each other in that one uses a constant load level and the other one uses constant temperature to isolate the effects of these factors on crack width. The model for crack width presented in the mechanistic-empirical pavement design guide was utilized to correct crack width values obtained under diverse temperature conditions. The model was adapted to predict crack width not only at the depth of the steel but at any depth and an enhancement is proposed to use the model for short-term prediction of changes in crack width. Continuous survey of the pavements for more than two years and the sequential application on each section of a large number of rolling-wheel loads at high load levels allowed for the observation of responses and failure mechanism. Under conditions of small crack width (less than 0.15 mm), load transfer capacity at the transverse cracks remained intact despite of traffic loads and seasonal thermal cycles. Failure of sections resulted from permanent deformation under the slab.