A test method to assess the frost resistance of concrete at the waterline of hydraulic structures

Abstract

Superficial damage, similar in appearance to salt scaling of concrete, has been observed at the waterline of hydraulic structures, such as hydro power structures, bridge columns, canals and harbours. Progressive damage to the concrete surface results in exposure of coarse aggregate. Deterioration rates of about 1 mm per year have been observed in some cases. A laboratory test method was developed in order to subject concrete specimens to exposure conditions similar to those prevailing at hydraulic structures in cold regions. Two concrete mixes were produced in order to study the effects of frost action on the deterioration of concrete at the waterline. The first mix was made of frost-resistant concrete with water to cement-ratio (w/c-ratio) 0.45, whereas the second mix was made of non-frost-resistant concrete with w/c-ratio 0.65. Regarding the specimens with w/c-ratio 0.65, scaling was observed at the waterline after 51 freeze–thaw cycles. The damage was caused by the effects of frost action, since the effects of leaching and erosion can be neglected in the test setup. No damage to the specimens with w/c-ratio 0.45 was observed. The laboratory test method proposed in this paper is considered appropriate for assessing the frost resistance of concrete at the waterline of hydraulic structures in cold regions.