Frost and Freeze/Thaw Resistance

Frost and Freeze/Thaw Resistance

Frost stress

Damage to concrete structures due to frost can generally be expected when they have been penetrated by moisture and are exposed to frequent freeze/thaw cycles in that condition. The damage to the concrete occurs due to the cyclic freezing and thawing of the water which has been absorbed due to capillary suction. Destruction follows due to the increase in volume of the water [ice] in the outer concrete layers.

Essentials for high frost resistance

·     Frost proof aggregates

·     Impermeable concrete structure and/or

·     Concrete enriched with microspores

·     Thorough and careful curing

·     Degree of hydration of the concrete as high as possible (i.e. it is not a good idea to place concrete immediately before periods of frost)

Test methods

·     Frost resistance

This can be estimated by comparing the fillable and non-fillable voids.

Freeze/thaw resistance

Given the extensive use of deicing salts (generally sodium chloride NaCl, intended to lower the freezing point of the water on roads and prevent ice formation etc.), the concrete surface cools abruptly due to heat extraction from the concrete. These interactions between frozen and unfrozen layers cause structural breakdown in the concrete.

Conditions for freeze/thaw resistance

·     Frostproof aggregates

·     Concrete with an impermeable structure enriched with microspores

·     Thorough and careful curing

·     Avoid too much fine mortar enrichment of the surface area

·     Concreting as long as possible before the first freeze/thaw stress so that the concrete can dry out.