A case study of evaluating joint performance in relation with subsurface permeability in cold weather region

- Freezing of subsurface layer contributes to the deterioration of joints in concrete pavements.
- Permeable subsurface layers are important for protecting concrete pavement from freeze-thaw distress.
- A borehole permeameter was developed in this work to directly measure the permeability of subsurface layer.
- Freezing of the moist base material can significantly reduce the permeability of subsurface layer.

Water that stays in a pavement system increases the risk of distress due to mechanisms such as freezing and thawing and erosion. This can be avoided by providing permeable subsurface layers to drain excess water from the pavement system. A borehole permeameter developed at Iowa State University was used in this research to measure the permeability of subsurface layers of an existing pavement with a view to investigating causes of joint distress. This research aims to increase understanding of the relationship between concrete pavement performance and the permeability of subsurface layers. Field borehole permeameter test results on a city street indicate that low permeable subsurface layer may contribute to joint deterioration under freezing condition. Laboratory falling head permeability tests on a similar base material under a frozen condition show that permeability of the samples decreases as moisture content increases, and freezing of the moist base material significantly reduces permeability.