Assessment of Concrete Footpath Upheavals in Heatwaves

Most concrete footpaths are cast without steel reinforcement and in segments between bituminous joints, with the joints intended to accommodate thermal expansions (and contractions) of the pavement. However, a combination of prolonged heatwave conditions and the ingress over time of material into the joints produces a situation in which the pavement does not deflect in its plane, but instead experiences a sudden upheaval buckle between the joints. These buckles are quite abundant, are increasing in number with hotter days, and they pose a risk to pedestrian safety, necessitating costly repair by regulatory bodies. Based on an energy formulation, this paper develops a solution in closed form with which to assess the vulnerability of a footpath to blow up (or to experience an upheaval buckle) on hot days as a function of the ambient temperature, material properties, and geometric layout. The solution allows for the design of a pavement that has a low probability of upheaval during its intended life, and for assessing the likelihood of existing pavements for such buckling.