Self consolidating concrete form pressure
The tiny entrained air voids act as empty chambers in the paste for the freezing and migrating water to enter, thus relieving the pressure in the pores and preventing damage to the concrete.Concrete with a low permeability (that is, a low water-cement ratio and adequate curing) is better able to resist freeze-thaw cycles.
Due to the natural accumulation of water under pavements in the base and subbase layers, the aggregate may eventually become saturated.
If adequate curing cannot be provided or if the concrete is exposed to freezing and thawing in the presence of deicer salts, the amount of fly ash should always be less than 25 percent. Different concretes require different degrees of durability depending on the exposure environment and the properties desired.
The Specifer’s Guide to Durable Concrete, EB221, is intended to provide sufficient information to allow the practitioner to select materials and mix design parameters to achieve durable concrete in a variety of environments.
The list of deicers used for these applications includes urea, potassium acetate, propylene glycol, and ethylene glycols.
Since scaling damage to pavements of all types is caused by physical salt attack, the use of high strength (4,000 psi or more), low permeability, air entrained concrete is crucial to good durability in these applications.
Then with freezing and thawing cycles, cracking of the concrete starts in the saturated aggregate at the bottom of the slab and progresses upward until it reaches the wearing surface.