Why does repeated freezing and thawing

D-cracking is different from other types of freeze-thaw damage because of its internal behavior. Other types of water damage, like spalling or scaling, both occur because of built-up water on the surface. However, these usually only occur on the surface of the concrete. Typically, pieces will fall off as this occurs. Repeated spalling can still cause structural damage over time, but it is also much easier to identify — whereas, D-cracking is difficult to identify until it has already caused significant damage.

Besides D-cracking, you may find that freeze-thaw conditions can cause scaling in concrete. It can start as small patches that later grow. Some causes of scaling include:. Locate A Dealer. Hardscaping stands in a unique position. Many pieces are made with varying climates in mind, but the wrong blocks can fall away or crumble in no time in freeze-thaw environments, so contractors and builders must still make informed choices. Pavers, a substantial component of hardscaping efforts, are usually made of interlocking pieces that offer more resistance to the effects of the freeze-thaw cycle.

They are typically denser and provide low permeability, which creates less room for water to enter. Freeze-thaw damage in pavers is less common because:.

Another helpful feature present in many hardscaping elements is the use of entrained air. Air entrainment adds air voids to concrete. Empty chambers are intentionally left in the paste so water can move into them as it freezes and gains volume, accommodating this change by reducing the stress on the concrete. The chambers lessen the pressure buildup in the pores and can help keep damage at bay. They also help to lower the permeability. Stones and bricks are other common components used in hardscaping that also get damaged from freeze-thaw cycles.

They similarly will see more damage if they get more moisture. For example, if one side of a wall gets hit with wind and rain more frequently than another, it will probably see the most freeze-thaw damage. As sunlight exposure changes, it can also affect the temperature of the water and its phase changes. Fortunately, there are ways to prevent or reduce the damage from freeze-thaw cycles. It usually requires completely replacing the damaged piece or brick, so preventing the damage instead is the ideal approach.

Some common methods for preventing freeze-thaw are:. One of the simplest ways to prevent concrete freeze-thaw damage is with deicing chemicals. These chemicals typically use a mixture of certain compounds to reduce the freezing point of the precipitation significantly.

If the freezing point lowers, the water remains in its liquid state and can pass through the concrete easily. It takes much colder temperatures than usual for it to freeze.

Sodium chloride is the most common mixture for ice-melting salt. Most other chemical mixes have similar results, like calcium chloride, which may be harder to store — magnesium chloride, which releases less chloride into the atmosphere — and potassium chloride, which causes less damage to vegetation.

Some applications have specific requirements about the chemicals that can be present in a deicer. Each fresh tissue was sectioned into seven aliquots and snap-frozen before undergoing repeated freeze-thaw cycles at room temperature or on ice. Biomolecules were extracted and analyzed. Both relative and absolute quantification were used to detect the changes in gene expression. Sample stability: a suggested definition and method of determination.

Desirable specifications for total error, imprecision and bias, derived from intra- and inter-individual biologic variation. Accessed: Design options for molecular epidemiology research within cohort studies. Cancer Epidemiol Biomarkers Prev ;— Your documents are now available to view. Confirm Cancel. Randi E. Cite this. You currently have no access to view or download this content.

Please log in with your institutional or personal account if you should have access to this content through either of these. Showing a limited preview of this publication:. Abstract Background: To maintain the best performance a frozen serum sample should be thawed once to prevent repeated freeze-thaw cycles. Results: Albumin, aspartate-aminotransferase ASAT , cholesterol, creatinine, C-reactive protein, glucose, immunoglobulin G, potassium, testosterone, triglycerides, urea and vitamin B12 levels did not show significant difference for pairwise comparisons after 10 repeated thaws.

Conclusions: Twelve components albumin, ASAT, cholesterol, creatinine, C-reactive protein, glucose, immunoglobulin G, potassium, testosterone, triglycerides, urea and vitamin B12 were robust to 10 repeated thaws compared to baseline level. Keywords: biobank ; biochemical component ; freeze-thaw cycles ; serum.

Received: Accepted: Published Online: Also, installation of effective drainage systems for carrying free water out from under the pavement may be helpful. Air entrainment - The severity of freeze-thaw exposure varies with different areas of the United States.

Local weather records can help determine the severity of exposure. The resistance of concrete to freezing and thawing in a moist condition is significantly improved by the use of intentionally entrained air.

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. In rare cases, air-void clustering can occur, leading to a loss of compressive strength.

More on air-void clustering. Scaling is defined as a general loss of surface mortar or mortar surrounding the coarse aggregate particles on a concrete surface. This problem is typically caused by the expansion of water due to freezing and thawing cycles and the use of deicing chemicals; however properly specified, produced, finished, and cured quality concrete need not suffer this type of deterioration. There is a distinct chain of responsibility for the production of scale resistant concrete.

Freezing temperatures. Concrete gains very little strength at low temperatures. Accordingly, freshly placed concrete must be protected against freezing until the degree of saturation of the concrete has been sufficiently reduced by cement hydration.