Characterization of Weathered Limestone Using Thermal Imaging and Split Tension Testing

Weathering of rock has a negative influence on both physical and engineering properties. For the design of infrastructure assets within weathered rock, it is imperative to determine the influence of weathering. Numerous techniques, both destructive and non-destructive, have been employed to assess the influence of weathering on rock properties. In this study, thermal characterization of weathered limestone specimens was conducted and results were evaluated in light of split tension tests. Thermal characterization consisted of heating the specimens to 200 degrees Celsius and recording the cooling of the specimens for 45 minutes with a thermal camera. A thermal time constant was determined for each specimen using the lumped capacitance method. The specimens were categorized into one of three weathering classes. Fresh or un-weathered specimens had the highest unit weight, highest average thermal time constant, and highest tensile strength.

Differentially weathered specimens had intermediate unit weights, intermediate average thermal time constants, and, on average, intermediate tensile strengths. The highly weathered specimens had the lowest unit weights and lowest thermal time constants. The fresh and highly weathered specimens exhibited classic tensile fracture patterns and the differentially weathered specimens exhibited surface activated fractures, which reflected their internal structures. There was a clear distinction between the average specimen thermal time constant and weathering classification. There was no clear distinction between tensile strength and weathering state. Results indicate that thermal characterization is a promising technique for the assessment of the weathering state of limestone laboratory specimens.