The most effective method to prevent frost action is to replace the soil that is prone to frost action with coarse-grained soils like gravels or coarse sand. As the water in coarse-grained soil drains out quickly, there is no chance for frost action to occur.
- The most effective method to prevent frost action is to replace the soil that is prone to frost action with coarse-grained soils like gravels or coarse sand. ...
- Providing an insulation blanket between the water table and the ground helps to avoid the migration of water to the top.
How do you prevent frost from freezing over?
Likewise, the recommended insulation will effectively prevent freezing of all frost-susceptible soils. Because of the heat absorbed (latent heat) during the freezing of water (phase change), increased amounts of soil water will tend to moderate the frost penetration or temperature change of the soil-water mass.
How to mitigate frost action in soil?
The following measures can be undertaken to mitigate the frost action in soils: The most effective method to prevent frost action is to replace the soil that is prone to frost action with coarse-grained soils like gravels or coarse sand. As the water in coarse-grained soil drains out quickly, there is no chance for frost action to occur.
How do you prevent frost action on gravel?
The most effective method to prevent frost action is to replace the soil that is prone to frost action with coarse-grained soils like gravels or coarse sand. As the water in coarse-grained soil drains out quickly, there is no chance for frost action to occur.
How can frost heave be prevented?
Damaged foundations and slabs. Generally, frost heave can be prevented by eliminating one of its basic elements which include fine grains soil, frost temperature, and water. There are several measures which can be considered to avoid frost heave : Provision of frost heave prevention systems such as hydronic heating system.
How do you fix frost action?
By extending the pavement section well into the frost depth, the depth of frost-susceptible subgrade under the pavement (between the bottom of the pavement structure and frost depth) is reduced. The assumption is that a reduced depth of soil under frost action will cause correspondingly less damage.
How do you prevent frost heaves on the road?
Heave is destructive and troublesome only during the freezing or frozen phase, when it varies sharply, causing uneven support to the pavement. To prevent frost heave, highly susceptible soils should be replaced or stabilized.
Does gravel prevent frost heave?
Frost-susceptibility is related to size distribution of soil particles. In general, coarse-grained soils such as sands and gravels do not heave, whereas clays, silts and very fine sands will support the growth of ice lenses even when present in small proportions in coarse soils.
How do you prevent frost heave in concrete slab?
To prevent frost heave, there are two general ways to handle a slab: Drain it or insulate it. One way is to drain beneath the slab, so there is no water in the soil to freeze. This could be challenging under a slab connected to ledge, since groundwater often follows the contour of ledge.
How do you insulate the ground from freezing?
The most common method for preventing freezing is to cover the ground with insulation. Insulating blankets and straw have both been successfully used. Another possible insulating method is to cover the ground with a waterproof plastic sheet and construct a pond of water above the subgrade.
Where frost action is most common?
It is most pronounced in high-altitude and high-latitude areas and is especially associated with alpine, periglacial, subpolar maritime and polar climates, but may occur anywhere at sub-freezing temperatures (between -3 and -8 °C) if water is present.
At what temperature does frost heave occur?
32 degreesWhile frost heaves usually occur in early spring, they can form anytime temperatures fluctuate above and below 32 degrees (F). Frost heaves result from a combination of cold air and adequate soil moisture. As the cold sinks to the ground, water within the soil starts to freeze.
Does frost penetrate concrete?
As the frost within the soil thaws and melts, the concrete can settle back towards its original position; however, it may remain raised if uneven base material develops beneath the concrete or if sufficient sized cracks develop. This cycle repeats itself every year and can continue to deteriorate the concrete.
How deep is the frost line in the ground?
0 to 8 feetThe line varies by latitude, it is deeper closer to the poles. Per Federal Highway Administration Publication Number FHWA-HRT-08-057, the maximum frost depth observed in the contiguous United States ranges from 0 to 8 feet (2.4 m). Below that depth, the temperature varies, but is always above 32 °F (0 °C).
Does sand frost heave?
Sandy soils are less likely to develop frost heaves, but can still freeze if the water table rises high enough. Structures built in areas with cold winters usually extend deep enough into the soil to avoid frost damage.
Does a concrete slab need to be below frost line?
A frost-protected slab does not need to be dug below the frost line, depending where you live, 12, 14, or 16 inches deep is enough (see chart below). A bed of compacted gravel caps the ground under the slab, and a drainage system should be installed in wet areas.
What causes frost heaves on roads?
The asphalt expands and contracts between cold nights that are followed by warm, sunny days, the blacktop soaking up the sun – and heat. But if temperatures stay below freezing, then frost heaves can form. They occur when water-soaked soil freezes and expands, which can turn smooth roads into mini rollercoasters.
At what temperature does frost heave occur?
32 degreesWhile frost heaves usually occur in early spring, they can form anytime temperatures fluctuate above and below 32 degrees (F). Frost heaves result from a combination of cold air and adequate soil moisture. As the cold sinks to the ground, water within the soil starts to freeze.
What causes frost heaving?
Frost heaving (or a frost heave) is an upwards swelling of soil during freezing conditions caused by an increasing presence of ice as it grows towards the surface, upwards from the depth in the soil where freezing temperatures have penetrated into the soil (the freezing front or freezing boundary).
How does frost heaving occur?
Frost heave is an upward swelling of soil due to the formation of ice during freezing conditions. It usually occurs when the freezing temperature penetrates the soil and turns the present moisture into ice thereby generating an upward movement in the soil.
Minimum Pavement Depths for Frost Protection
Pavement structures are often designed to penetrate a significant distance into the average frost depth. In the simplest case, several State Highway Authorities (SHAs) use a rule-of-thumb that the pavement structure should equal at least one-half of the expected depth of freeze.
The 1993 AASHTO Guide
The 1993 AASHTO Guide contains a treatment based on reduced subgrade support. Its goal is to estimate the differential effects on the road profile and ultimately to estimate the residual effects on the Present Serviceability Index (PSI). Thus, the decrease in PSI with time due to frost effects is added to the loss of PSI due to ESALs.
Army Corps of Engineers
The Army Corps of Engineers design procedures for pavements subject to freezing and thawing in the underlying soils are based on two concepts (Lobacz et al., 1973 [1] ):
Granular or Rock Cap
One fundamental way to reduce frost action in a pavement is to stop (or reduce) the available water from forming ice lenses and provide a positive drainage blanket to prevent saturating the upper layers of the pavement structure. Tabor commented on this in 1930:
Geotextiles
Geotextiles have frequently been used as separators and occasionally as filters. Work performed by Bell et al. (1983) at Oregon State University suggests that geotextiles have potential as capillary breaks.
Additional Considerations
The preceding methods are just several of the more common approaches to frost action prevention. They are not intended to be a comprehensive list. Other considerations not discussed include but are not limited to:
Why is frost action less severe?
By breaking the capillary flow path, frost action will be less severe because as Tabor (1930 [1]) noted, frost heaving requires substantially more water than is naturally available in the soil pores.
What happens if you remove any of the three conditions above and frost effects will be eliminated or at least minimized?
If the three conditions occur uniformly, heaving will be uniform; otherwise, differential heaving will occur resulting in pavement cracking and roughness . Differential heave is more likely to occur at locations such as:
What is thawing a subgrade?
Thawing is essentially the melting of ice contained within the subgrade. As the ice melts and turns to liquid it cannot drain out of the soil fast enough and thus the subgrade becomes substantially weaker (less stiff) and tends to lose bearing capacity. Therefore, loading that would not normally damage a given pavement may be quite detrimental during thaw periods (e.g., spring thaw). Figure 3 is an example of typical pavement deflection changes throughout the year caused by winter freezing and spring thawing. Figure 4 shows pavement damage as a result of thaw weakening.
How does frost affect soil?
Frost heaving of soil is caused by crystallization of ice within the larger soil voids and usually a subsequent extension to form continuous ice lenses, layers, veins, or other ice masses. An ice lens grows through capillary rise and thickens in the direction of heat transfer until the water supply is depleted or until freezing conditions at the freezing interface no longer support further crystallization. As the ice lens grows, the overlying soil and pavement will “heave” up potentially resulting in a cracked, rough pavement (see Figure 1). This problem occurs primarily in soils containing fine particles (often termed “frost susceptible” soils), while clean sands and gravels (small amounts of fine particles) are non-frost susceptible (NFS). Thus, the degree of frost susceptibility is mainly a function of the percentage of fine particles within the soil. Many agencies classify materials as being frost susceptible if 10 percent or more passed a 0.075 mm (No. 200) sieve or 3 percent or more passed a 0.02 mm (No. 635) sieve. Figure 2 illustrates the formation of ice lenses in a frost susceptible soil.
How does a freeze thaw happen?
Freeze-thaw damage. Thawing can proceed from the top downward, or from the bottom upward, or both. How this occurs depends mainly on the pavement surface temperature. During a sudden spring thaw, melting will proceed almost entirely from the surface downward.
Who proposed the rule of thumb for identifying potentially frost susceptible soils?
In 1932, Dr. Arthur Casagrande proposed the following widely known rule-of-thumb criterion for identifying potentially frost susceptible soils:
When to apply load restrictions?
Load restrictions “should” be applied after accumulating a Thawing Index (TI) of about 25 °F-days (based on an air temperature datum of 29 °F) and “must” be applied at a TI of about 50 °F-days (again based on an air temperature datum of 29 °F). Corresponding TI levels are less for thin pavements (e.g., two inches of HMA and six inches of aggregate base or less) in that the “should apply” TI level is 10 °F-days and the “must” TI level is 40 °F-days.
What to do if you have frostbite?
If you notice signs of frostbite on yourself or someone else, seek medical care. Check to see if the person is also showing signs of hypothermia. Hypothermia is a more serious condition and requires emergency medical care.
What to do if you have frostbite but no signs of hypothermia?
If (1) a person shows signs of frostbite, but no signs of hypothermia and (2) immediate medical care is not available, do the following: Get the person into a warm room as soon as possible. Unless absolutely necessary, do not walk on feet or toes that show signs of frostbite—this increases the damage.
How to treat frostbite on hands?
If warm water is not available, warm the affected area using body heat. For example, you can use the heat of an armpit to warm frostbitten fingers.
How to treat hypothermia?
In this case, handle the person gently, and get emergency assistance immediately. Perform CPR, even if the person appears dead. CPR should continue until the person responds or medical aid becomes available.
What is the damage of freezing?
Frostbite is a type of injury caused by freezing. It leads to a loss of feeling and color in the areas it affects, usually extremities such as the nose, ears, cheeks, chin, fingers, and toes. Frostbite can permanently damage the body, and severe cases can lead to amputation (removing the affected body part).
How to tell if you have frostbite?
If you notice redness or pain in any skin area , get out of the cold or protect any exposed skin—frostbite may be beginning. Any of the following signs may point to frostbite: A white or grayish-yellow skin area. Skin that feels unusually firm or waxy. Numbness.
What to do if you can't get medical help?
If you are not able to get medical help right away, try to warm the person up. Get the person into a warm room or shelter. Remove any wet clothing the person is wearing. Warm the center of the person’s body—chest, neck, head, and groin—using an electric blanket, if available.
How to prevent frost heave?
To prevent frost heave, highly susceptible soils should be replaced or stabilized. Frost heave spots should be drained with tile drains and/or ditches should be kept clean and free of clutter that prevents flow of water away from the pavement.
What is frost action?
Frost action is a phenomena that occurs in the winter and early springtime in Northern climates. Practically all surface soils undergo some frost action, the magnitude of which is dependent upon the locally prevailing climate and precipitation. Frost action divides into two phases: freezing the soil water, and thawing the soil water. For pavements, frost action becomes critical when either (1) the freezing phase is accompanied by noticeable heaving of the road surface, or (2) the thawing phase is accompanied by a noticeable softening of the roadbed.
What are the conditions that must exist before frost heaving can occur?
They are: A sufficiently cold climate to allow freezing temperatures to penetrate below the road surface into the subbase and subgrade. A supply of water from below, above and/or laterally into the freezing zone.
Why is silt important for freezing?
Silt, because of the extremely small size of its particles, or gradation, permits and encourages the flow of water by capillary action through its pores . Consequently, silts supply the water necessary to promote the formation of ice lenses in the freezing zone. Other soils considered frost susceptible include fine sands, ...
What are the two phases of frost action?
Frost action divides into two phases: freezing the soil water, and thawing the soil water. For pavements, frost action becomes critical when either (1) the freezing phase is accompanied by noticeable heaving of the road surface, or (2) the thawing phase is accompanied by a noticeable softening of the roadbed.
What is the term for the heaving of the road from frost action?
Heaving of the road from frost action is termed "frost heave.". Frost heave, particularly when in isolated areas, induces uneven support of a pavement. When a heavy load passes over the area of uneven support, a crack may form in the pavement surface layer. There are at least three conditions, all of which must exist before frost heaving can occur.
How does free water migrate through soil?
Free water migrates through the soil to a forming ice lens by capillary action (akin to wicking). This migration of water can be as far as 20 feet for certain frost susceptible soils.
How does frost heave affect roads?
Frost heave inflicts considerable damage to roads, channels, foundations and subsequently, the superstructure. In order to prevent the detrimental effects of frost heave, it is necessary to understand how it works and identify the basic elements which lead to its occurrence. After that, proper measures can be set up to prevent it.
How to prevent ice from gripping concrete?
Use sleeve to avoid ice from gripping the concrete. Construct footing that withstands upward movement. For road construction, replace fine grain frost susceptible soil with coarse granular soil. Use capillary breaker so as to prevent movement of water toward freezing front and consequently decline frost heave influence.
What happens when freezing temperatures penetrate the soil?
When freezing temperature further penetrates into the soil, it leaves ice lenses behind. These ice lenses continue to grow towards the area that loses temperature which is toward soil surface. The ice lenses are capable of thrusting the soil layer upward.
What happens when the temperature of ice drops?
When temperature declines, the ice melts and the structure lows back to its location under its weight. When freezing and thawing process repeats, it would severely deteriorate and possibly collapse.
What happens when moisture turns into ice?
It is reported that, when moisture converts to ice, its size increases by 9%. Fine grain frost-susceptible soil, moisture that continuously supplies water to ice lenses, and freezing temperature are the basic elements of frost heave action. When temperature declines, the ice melts and the structure lows back to its location under its weight.
What are the conditions that can cause frost?
The following list are some meteorological conditions that can lead to frost conditions: Clear skies lead to radiational cooling, allowing the greatest amount of heat to exit into the atmosphere. Calm to light winds prevent stirring of the atmosphere, which allows a thin layer of super-cooled temperatures to develop at the surface.
What are the factors that affect the possibility of frost forming?
Other local effects, such as soil moisture/temperature and stage of vegetation "greenness" are factors that can affect the possibility of frost forming.
What happens when you cool to the dew point?
If the super-cooled, freezing temperatures can cool to the dew point (the temperature at which, when cooled to at constant pressure, condensation occurs; moisture will have to come out of the atmosphere as fog, frost, etc) frost could develop on exposed surfaces.
What temperature can cause frost?
A local study done on frost formation relating temperature to dew point has these guidelines for frost: temperatures from 38 to 42 F can lead to patchy frost, 33 to 37 areas of frost, and 32 and below widespread frost/freeze.
How does topography affect frost?
Local topography has a large role in determining if and where frost develops. Cold air will settle in the valleys since it is heavier than warm air, therefore frost conditions are more prone in these regions. Valleys also shelter the area from stronger winds, enhancing the potential for frost.
What temperature is needed to make ice crystals?
For example, if conditions are favorable, air temperatures could be 36 F, but the air in contact with the surface could be 30 degrees or colder. Cool temperatures , with some moisture, that promote ice crystal development.
What are Frost-Protected Shallow Footings and Why Are They Used?
The goal is to protect foundations from frost heaving.
Why is a footing insulated?
Heat loss occurs outward from the foundation walls and is, therefore, intensified at the proximity of an outside corner because of the combined heat loss from two adjacent wall surfaces. Consequently, to protect foundation corners from frost damage, greater amounts of insulation are required in the corner regions. Thus, an insulated footing design will provide additional protection at corners where the risk of frost damage is higher.
How does geothermal heat affect frost depth?
Geothermal heat from the underlying ground also helps to raise the frost depth around the building.
Why do you need vertical wall insulation?
Because the vertical wall insulation around a foundation extends above grade and is subject to ultraviolet radiation and physical abuse, that portion must be protected with a coating or covering that is both tough and durable.
Does frost line rise above a foundation?
It is important to note that the frost line rises near a foundation if the building is heated. This effect is magnified when insulation is strategically placed around the foundation. The FPSF also works on an unheated building by conserving geothermal heat below the building.
Does frost need to penetrate below footings?
With ad-freezing (the frozen bond between the water in the soil and the foundation wall), frost does not need to penetrate below footings to be dangerous to light construction. In this sense, frost protected footings are more effective in preventing frost damage.
Does horizontal insulation help with frost damage?
Second, horizontal insulation projecting outward will shed moisture away from the foundation further minimizing the risk of frost damage. Finally, because of the insulation, the frost line will rise as it approaches the foundation. Since frost heave forces act perpendicular to the frost line, heave forces, if present, ...
Frost Heave
Thaw Weakening
Sources of Water
- The two basic forms of frost action (frost heave and thawing) both require water. Water sources can be separated into two broad categories: 1. Surface water. Enters the pavement primarily by infiltration through surface cracks and joints, and through adjacent unpaved surfaces, during periods of rain and melting snow and ice. Many crack-free pavements are not entirely impermea…
Estimation of Freezing Or Thawing Depths in Pavements
- This section discusses freeze depth estimation techniques. Such an estimate is helpful in designing for frost conditions, but oversimplifies the complex conditions that accompany various pavement materials, depths of freeze, and water sources. Basic terminology is contained on a separate page. All units will be in U.S. customary due to the source material. Two formulas are p…
Mitigating Frost Action
- Mitigating of frost action and its detrimental effects generally involves structural design considerations as well as other techniques applied to the base and subgrade to limit the effects of frost action. The basic methods used can be broadly categorized into the following techniques: 1. Limit the depth of frost into the subgrade soils. This is ty...
Freezing and Thawing Implications For Maintenance Operations
- The calculated freezing index (FI) and thawing index (TI) can be used to estimate the depth of freeze at a specific site and the resulting thaw. Maintenance personnel can use the TI to assess the need for seasonal load limits (Figure 5). The following general guidelines relative to spring highway load restrictions were developed and evaluated by a study in Washington State (Rutherf…
Frost Action Summary
- Frost action is a critical pavement structural design concern in those parts of the country that regularly experience ground freezing. Without proper precautions, severe frost action can destroy a new pavement in a matter of one or two years. In taking the proper precautions, there are two basic types of frost action with which to contend: 1. Frost heave. Results from accumulation of …