MODELING OF ENVIRONMENTAL EFFECTS ON THERMAL DETECTION OF SUBSURFACE DAMAGE IN CONCRETE

摘要

A significant form of deterioration in concrete is corrosion of embedded reinforcing steel that can cause subsurface delaminations and spalling. Infrared thermography can be used to detect delaminations based on variations in surface temperature that are caused by the disruption of the heat flow through the delaminated area. The surrounding environmental conditions such as sunlight, ambient temperature variation, and wind speed are critical for heat transfer, and as such the technology depends on these environmental conditions. This paper describes a numerical model developed to predict thermal contrasts for subsurface delaminations based on a given set of environmental conditions surrounding the concrete. The finite element method (FEM) was used to perform 3-D nonlinear transient heat-transfer analysis of a large concrete block with embedded Styrofoam targets intended to provide an idealized model of subsurface delaminations. The effectiveness of the modeling was evaluated by comparing the thermal contrasts predicted by the model and those obtained from experimental testing of an actual concrete block of the same dimensions. The correlation and error between the experimental testing and the model results indicated that the model could be an effective tool for the prediction of anticipated thermal contrasts based on given weather conditions.