Deterioration of Concrete by Cyclic Freezing and Thawing
Cyclic freezing and thawing can cause severe damage to concrete. the freezing and thawing will damage the concrete if the concrete undergoes cyclic freezing and thawing and if the pores inside concrete nearly saturated to more than 90% during freezing. The water volume will increase by almost 15% during freezing. Expansion of water inside the concrete pores will exert tensile stresses on concrete, which may damage concrete. These stresses can fracture the cement matrix and cause severe damage to concrete, which may reduce concrete durability.
This type of deterioration occurs from outside to inward in an almost layering manner. The rate of progression of freeze-thaw deterioration depends on the numbers of freeze-thaw cycles, condition of exposure, the porosity of concrete, and the degree of saturation during the freezing. The tops of walls exposed to snowmelt or water spray, horizontal slabs exposed to water, and vertical walls at the waterline are the locations most commonly damaged by freeze-thaw deterioration.
Another type of freeze-thaw deterioration called D-cracking. In this type of freeze and thaw, the expansion occurs in low quality, absorptive coarse aggregates instead of concrete. This type of deterioration commonly occurs at the corner of exposed walls and slabs formed by joints. In this type of deterioration, a series of roughly parallel cracks exuding calcite usually cut across the corners.
The using air-entraining admixture can protect concrete from freeze and thaw deterioration. Air-entraining admixture will form a series of small air bubbles inside the concrete. During the freezing, these air bubbles will accommodate the increase of water volume, which relieves the tensile stresses and prevent concrete deterioration. Using the correct concentration of AEA will significantly reduce the effects of freeze and thaw deterioration expect in very severe climates.
The damage due to cyclic freezing and thawing will occurs when the concrete is nearly saturated. Therefore reduce the degree of concrete saturation and reducing or eliminating the freezing and thaw cyclic will significantly reduce the damages of concrete surface. Also, sealing the concrete surface by sealing compound will significantly reduce the effects of freeze and thaw cyclic.
Repairing of damaged concrete due to freeze and thaw can be done by replacing the damaged concrete. The replacement concrete must contain air-entraining admixture to protect concrete from further damage due to freeze and thaw cyclic.