Field test method for residual stress in plain concrete pavements and structures

Residual stresses form in concrete structures and rigid pavements as a result of differential shrinkage, loss of subgrade support, and physical restraint by the superstructure. These stresses diminish a concrete member's capacity to carry its design load, making the structure vulnerable to premature cracking and failure. Few methods for quantifying the residual stress in concrete exist, although several methods have been developed for measuring material stresses in metals and rocks. Here, a new field test method for concrete pavements and structures, inspired by the ASTM E837 method for measuring residual stress in steel, is presented. The test is performed by installing strain gages on the surface of a concrete pavement or structure and then saw-cutting around the gages to isolate the gages from the bulk concrete material. The difference between the strain reading before and after the saw-cuts is used to compute the stress present at the surface of the concrete material. The method was developed and validated in laboratory experiments, and finite element modeling was conducted to enhance understanding of the three-dimensional strain distribution around saw-cut notches in materials with residual stress. Full-scale testing on plain concrete pavements demonstrated the method's potential as a field test method.