Effect of slab curling on movement and load transfer capacity of saw-cut joints

Abstract

The effect of slab curling on the development of cracking at saw-cut notches and long-term joint movement in the concrete pavement sections of the Korea Highway Corporation test road was investigated in addition to joint deflections and load transfer efficiency (LTE) at the joints. During paving operations, 50 joints were saw-cut immediately after the occurrence of a random crack in the concrete pavement. The location and the time of the uncontrolled cracking were observed by a comparison of the tensile strength of the concrete with the tensile stress developed by the slab curling because of the temperature difference between the top and bottom of the slab. The development of cracking and movement of the saw-cut joints and random cracks were observed over a 2-year period after construction. The relationship between the initial and long-term joint movements is presented. The deflections and LTE at the joints and random cracks were measured by using the failing weight deflectometer 2 years after concrete placement. The effect of slab curling due to a permanent built-in temperature difference on the deflection at the joint is described. In addition, the effect of dowel locking due to the upward slab curling on the load transfer capacity of the joint is presented.