Freeze Thaw and ASTM C-672

Durability is the ability of concrete to resist weathering action, chemical attack and abrasion while maintaining its desired engineering properties. How durable concrete products need to be depends on the kind of environment they will be exposed to. As cold weather approaches, concepts like freeze-thaw and resistance to deicing salts become important to understand. When water freezes, it expands 9%. As the water in moist concrete freezes, it produces pressure in the pores of concrete. If this pressure exceeds the tensile strength, the cavity will dilate and rupture. Successive freeze-thaw cycles will then eventually cause expansion and cracking, scaling, and/or crumbling of the concrete. Deicing chemicals, used for snow and ice removal, can aggravate freeze-thaw deterioration. Therefore, when using cement products, such as patching materials, on concrete roadways it is important that these materials have a strong resistance to the effects of these harsh conditions and chemicals.

ASTM C-672 is the standard test method for Scaling Resistance of Concrete Surface Exposed to Deicing Chemicals. It covers the determination of the resistance to scaling (local flaking or peeling of a finished concrete surface) of a horizontal concrete surface exposed to freeze-thaw cycles in the presence of deicing chemicals. The test is intended for use in evaluating this surface resistance qualitatively by visual examination.

How is the test performed? Specimens are placed in a solution of calcium chloride and water with a concentration that imitates deicing salts; they are then placed alternatively in a freezing environment and a room temperature environment. This cycle is repeated daily and the surface is flushed off thoroughly at the end of every 5 cycles to visually examine the surface. Generally, 50 cycles is sufficient to evaluate the surface and the condition of the surface is reported using a rating scale from 0 to 5; meaning there is no scaling present and 5 indicating there is severe scaling (coarse aggregate is visible over the entire surface). Quality patching products, like US SPEC Transpatch, should be displaying scaling resistance after this 50 cycle test.