Frozen Ground: Understanding How and Why it Freezes

On December 31, 1967, the Green Bay Packers and the Dallas Cowboys competed for the NFL Championship in Green Bay, Wisconsin. They played in temperatures as low as -25° Celsius (-13º Fahrenheit). The players noticed that the field became so hard their cleats could not dig into the normally soft soil. They slipped and struggled to stay upright. Why? The ground had frozen solid. This historic game is known as the Ice Bowl.  Frozen ground played havoc with the game.

Frozen Ground

Frozen ground occurs when the ground contains water, and the temperature of the ground goes below 0° Celsius (32° Fahrenheit). More than half of all the land in the Northern Hemisphere freezes and thaws every year, and is called seasonally frozen ground. One-fourth of the land in the Northern Hemisphere has an underground layer that stays frozen all year long. If the ground remains frozen for at least two years in a row it is called permafrost.

What makes the ground freeze?

When ground is frozen solid, the water between the rocks, soil, and pebbles, and even inside the rocks, has frozen and becomes pore ice. So officially, the ground freezes when the water in the ground becomes ice.

How does the density of water affect frozen ground?

When water turns into ice, it can expand with great force and cause the ground to swell. In areas with a cold winter season frozen ground can damage roads. For example, water turning to ice under roads sometime creates frost heave. The expanding ice pushes up the road and creates a hump, which later, after a thaw, will create potholes  and sunken sections in a roadway.

The ground below is not all the same temperature

When the temperature of the ground drops below 0° Celsius (32° Fahrenheit), it freezes; however, the ground temperature can be different from the temperature of the air above it. Layers deep within the ground may be colder or warmer than layers near the surface of the ground.

The top layer of ground may respond to conditions on the surface, but the layers below may not change as quickly. On a warm summer day, the surface of the ground absorbs  heat and becomes hotter than the air. But the temperature a few feet underground may be much lower than the air. It is the opposite in the winter; the surface of the ground cools, but the layer deep underground may stay warmer than the surface. The upper layer of ground stops heat from moving between the cold air and the deeper layers of the ground, insulating itself.

The ground is not the only thing that insulates itself from the air. For example, imagine a lake on a hot summer day. The first few feet of the lake will be warm. But closer to the bottom of the lake, the water will be much cooler. The Sun’s heat has less effect on the water deeper below the surface. This layering of temperatures is called a temperature gradient.

The type of soil in an area also affects how the ground will store heat. Loose soils like sand have more space for water and ice forms more easily. Dense soils with small particles do not have as much space for water. Clay, for example, does not freeze as easily as sand.

How deep does the ground freeze?

The depth of frozen ground depends on the length of time the air is cold. The longer the cold period, the deeper the ground will freeze. But the depth of frozen ground is limited, because Earth is warm deep inside.

Most of Earth’s heat comes from the Sun (Figure 1). The ground stores a lot of the Sun’s heat and reflects the rest into the air. Snow and ice are light colored and reflect more heat away. Ocean water and bare ground reflect less heat, instead absorbing it. This transfer of heat between the ground and the air is called the surface energy flux.

energybalance_small

Figure 1. This diagram shows how the Earth’s atmosphere and the ground reflects and absorbs the Sun’s energy.

Credit: NASA Atmospheric Science Data Center

 

Heat is also coming from the inside of the Earth. The Earth’s core is very hot, and its heat moves towards the surface–geothermal heat flux (Figure 2).

insideearth

Figure 2. Deep inside, the Earth is hot. The mantle and liquid outer core are molten rock. The inner core is solid, but it too is hot. This heat moves through Earth’s layers to the surface.

Credit: Lawrence Livermore National Laboratory

 

Heat from volcanoes, rivers, lakes, and other sources can also spread through the ground. This heat keeps some areas unfrozen, even though surface temperatures are low.

In general, deeper permafrost is very old. One researcher found that the deepest part of the permafrost underneath Prudhoe Bay, Alaska, is more than 500,000 years old.

How does the local landscape affect frozen ground?

Temperature swings, seasonal changes, and location are not the only things that affect frozen ground. Snow, soil, plants, and other aspects of the local landscape also affect frozen ground.

Snow

A thick layer of snow acts like a blanket so that heat does not leave the ground. Only a thin layer of ground will freeze under a thick layer of snow.

Soil type

Some soils freeze more easily than others. Light-colored soils freeze sooner and stay frozen longer than dark soils. Light-colored soils and rocks reflect sunlight, keeping the ground cooler.

Peat

Peat is soil that forms when dead plants do not decompose all the way. Peat is found in marshy areas that form when the active layer thaws. The ground under peat is usually colder than ground not covered by a peat layer.  In the winter, peat freezes and allows heat to leave the ground. Because the heat escapes, more frozen ground and permafrost form.

Plants

In the summer, plants keep the soil underneath them cooler because they block some sunlight from reaching the ground. Evergreen trees especially keep the ground cooler. Evergreen trees do not lose their leaves in the winter. This means that the trees block sunlight from warming the ground. Plus, their branches block snow from reaching the ground underneath. The bare ground loses heat more easily. Permafrost often forms under evergreen trees.

Slopes

Hillsides and mountain slopes can affect frozen ground and permafrost.

If a slope gets more sunlight because of the way it faces, the ground will be warmer and will be less likely to freeze. In the Northern Hemisphere, slopes that face south, towards the Sun, get more sunlight than shady slopes that face north. The opposite is true in the Southern Hemisphere.

Steep slopes are likely to contain frozen ground. The steepness of the slope affects how much sunlight it gets. Steep slopes do not get as much direct sunlight, so they are colder. Steep slopes do not hold snow cover very well, so the bare ground loses more heat. Wind direction also affects whether frozen ground forms. If a slope faces into the wind, the ground will lose more heat. Plus, the wind will blow snow away making the ground even colder.

Lakes and rivers

Lakes and rivers are sources of heat in cold places. The water is warmer than the surrounding air and can keep the ground beneath it warmer in the winter. Lakes and rivers might not have frozen ground under them. Or, they might have a thicker active layer compared to nearby land.

The Powerblanket® Solution for Frozen Ground

Frozen ground is a reality many industrial companies must face.  The high watt density in Powerblanket Ground Thawing Blankets helps tackle the difficulty of thawing ground in harsh climates.  Use a Powerblanket ground heater to save time, money, and stress.  

 

“Your blankets are absolutely excellent. Thanks to the Powerblankets, we were able to quickly thaw the ground and complete our job. In fact, we estimate a savings of 10 hours per site equaling a savings of $5,000 already. Calculating this to our thousands of sites, the savings is huge! We are excited about the time and money Powerblanket has saved us and look forward to future savings.”

—Kim Herman OSP/COEI Operations Manager Precision Utilities Groupfrozen ground

 

Why Choose Powerblanket Ground Heaters?

  • High power density thaws frozen ground
  • Quickly remove frost prior to concrete pour
  • Melt snow and ice from roofs, walkways, and construction areas
  • Easily installed and removed
  • Provides higher heat control when combined with a thermostatic controller
  • Saves time, money, and labor

learn-more-ground-thawing-01

 

“All About Frozen Ground.” National Snow and Ice Data Center. Accessed 20 December 2016. https://nsidc.org/cryosphere/frozenground.

5 Helpful Tips for Winter Construction Efficiency

5 Tips for Winter Construction

Working outside during the cold winter months presents many obstacles; however, some jobs will not wait for better circumstances. Below are some tips and solutions to improve winter construction.

1) KEEP YOUR EMPLOYEES SAFE

Train your employees in proper winter construction precautions.  Encourage everyone to wear layers of loose-fitting clothing, to stay dry, and to protect from the wind and sun with gloves, hats and sunscreen.  If conditions become too cold/dangerous, employees should have access to shelter.

On the work site, remove ice and snow regularly to prevent slips and falls.  This can be a full-time job depending on the weather.  The act of shoveling snow can also be extremely strenuous, especially for those individuals who do not engage in regular cardiovascular activity. According to the Cleveland Clinic, approximately 11,000 people seek shoveling-related hospital treatment each year for injuries (93%) or cardiac issues (7%). To save time, energy, and your employees health, use Summerstep heated safety mats to keep the walkways on your construction site clear.

Summerstep Snow Melting Mats

  • ,  Protect personnel from winter weather conditions and keep stairs, doorways, walkways, and ramps free from snow and ice
  •   Prevent slips and falls
  •   More convenient than shoveling snow
  •   More effective for snow and ice melting than harsh chemicals (less damaging to the environment, reusable, won’t damage concrete or other flooring surfaces)
  •   Will melt approximately 2 inches of snow per hour when operating
  •   40 Watts/Sq ft heated area
  •   The ONLY snow melting mat product made in the USA

learn-more-summerstep-01

2) MAINTAIN INTEGRITY OF CONCRETE

Winter construction cold-weather operations aren’t just about safety. While most construction tasks can be carried out in cold weather, some operations, such as concrete work, can take much longer and even fail without proper precautions.

 

If concrete is to reach necessary strength levels, it can’t be allowed to freeze for the first 24 hours after being poured or placed. Sheeting the concrete can ensure the required temperature and moisture necessary for curing, if the weather isn’t too severe.  In severe conditions, supplemental heating systems or enclosures must be brought in to maintain the integrity of the concrete.

 

Powerblanket Concrete Blankets provide a manageable way to cure concrete in the cold weather months, save you time and money, and come in various lengths and sizes. We have you covered.

 

Powerblanket Concrete Curing Blankets

  •   Cure concrete 2.8 times faster than conventional insulated blankets
  •   Produce cold weather concreting strength of 3,925 psi in 72 hours
  •   Maintain moisture throughout hydrating process
  •   Easily installed and removed
  •   Maintain ACI compliance for cold-weather concreting  Certified to UL and CSA standards

learn-more-concrete-blankets-01

3) DON’T LET FROZEN GROUND SLOW YOU DOWN

When it’s cold and the ground freezes, the job suffers.  Often prep for winter construction takes longer than the actual job.  Some industrial companies try heating the ground with massive coils or large heating systems, which become expensive and cumbersome. This approach requires rental fees and transporting equipment.  

Powerblanket has considered the difficulties and delays associated with winter construction and cold/freezing temperatures and has created a solution.  With Powerblanket’s patented heating technology you can prep the ground with little to no effort or supervision on your part.

Powerblanket ground thawing blankets have a higher power density and hotter temperature than our concrete curing blankets. The higher power is iideal for ground thawing applications and curing epoxy or resins.

Why Powerblanket Ground Thawing Blankets?

  •   High power density thaws frozen ground quickly
  •   Remove frost prior to concrete pour
  •   Melt snow and ice from roofs, walkways, and construction areas
  •   Easily placed and removed for repeated use in harsh winter weather
  •   Can be used to cure epoxy and resins
  •   Certified to UL and CSA standards

learn-more-ground-thawing-01

4) KEEP MATERIALS WARM

Masonry, roofing, paint, and plaster/stucco materials are all sensitive to cold weather.  Maintaining the integrity of these materials is critical for their success in winter construction.

Powerblanket Hot Boxes save you money by keeping your products from freezing without the risk of overheating. The Hot Box pallet warmer is easily assembled, taken apart. Hot boxes are ideal for cold wea
ther storage, freeze protection, transporting, job site heating, remote location use, and winter roofing. Standard Hot Boxes hold product between 100°F and 120°F (38°C and 49°C) and optional adjustable thermostatic controllers allow temperatures to be precisely controlled.

Powerblanket Hot Boxes:

  •   Quick and easy assembly
  •   Preserve temperature sensitive material
  •   Heat materials and palletized products: adhesives, shingles, paint, caulk, resins epoxies, etc.
  •   Access doors on two sides.
  •   Certified to UL and CSA standards

learn-more-hot-boxes-01

5) USING A PROPANE HEATER

Winter construction professionals often use temporary, propane-powered heating equipment on the jobsite, making it easier to finish projects on time and on budget. In addition to providing more comfortable working conditions, propane-powered heaters can also maintain the ambient temperatures necessary for common tasks like drywall installation or painting. However, like any portable heating device, propane-powered heaters must be used and maintained properly.

When temperatures get too low, the propane will not flow consistently or effectively, and you may lose your heat altogether. Propane-tank efficiency will fall substantially as the temperature drops. As the temperature drops, so does the pressure in your propane tank, and the pressure in your propane tank directly affects the volume of propane you have to work with. Your extraction rate (how quickly and smoothly you can extract propane from the tank) will suffer as well. Without a heating source to assist in the pressure maintenance of your tank, you will have to keep it as full as possible in order to keep it working, even if temperatures are mildly cold.

Powerblanket Propane Tank Heater

Powerblanket has the best propane tank heating solution on the market. These heating blankets will help maintain pressure and efficiency on just about any size tank. All Powerblanket heating blankets are certified to UL and CSA safety standards

Benefits of Powerblanket Propane Tank Heaters:

  •   Increase performance and efficiency of propane tanks
  •   Eliminates unnecessary cylinder refills in cold weather
  •  Even heat distribution in the areas where it is needed most
  •   Save money by optimizing gas and material usage
  •    Certified to UL and CSA standards

learn-more-propane-tank-01

 

Ground Thawing Blankets: Prep Frozen Ground with Powerblanket

When it’s cold and the ground is frozen, your job suffers. Thaw frozen ground and get back to work quickly with Ground Thawing Blankets from Powerblanket.

Winter is an interesting beast, especially for those who make their livelihood working outside.  Often prep takes longer than the actual job itself.  Powerblanket has considered the difficulties and delays associated with cold and freezing temperatures and has created a solution.  With Powerblanket’s patented heating technology you can prep the ground with little to no effort or supervision on your part. 

Ground Thawing for Commercial Plumbing

A south-central Utah plumber said, “I wish I had known about Powerblanket’s ground thawing blankets a couple years ago.  We had a job in Mount Pleasant that got so cold that we couldn’t dig.  We started laying out thermal blankets every night to avoid the hard freeze that happened overnight.  We had to layer the thermal blankets in order to keep the ground warm enough to work each morning.  Our progress was slow and labored, and we never knew what we would find at the job site each morning.  It would have been so much easier if we had had Powerblankets.”

Some industrial companies also try heating the ground with massive coils or large heating systems, which becomes expensive and cumbersome. This approach requires rental fees, transporting equipment, and a bit more money than the bid allows.  Your ground thawing blanket can be used over and over on any frozen job you have.

The high power density in Powerblanket Ground Thawing Blankets helps tackle the difficulty of thawing ground in harsh climates. This line of Powerblanket flat blankets has a higher power density and hotter temperature than our concrete curing blankets. The higher temperatures are ideal for ground thawing applications and curing epoxy or resins.

Why Powerblanket Ground Thawing Blankets?

  • High power density thaws frozen ground quickly
  • Remove frost prior to concrete pour
  • Melt snow and ice from roofs, walkways, and construction areas
  • Easily placed and removed
  • Can be used to cure epoxy and resins

Learn More Here Button-02

Grave Digging and Ground Thawing

We’re gradually approaching warmer weather now, but it’ll still be some time before the ground thaws and makes digging a lot less difficult. That’s why we’d like to introduce you to our Ground Thawing Blankets. For those in concrete, grave digging, utility maintenance, or any other digging / ground-prep-related project, Powerblanket® Ground Thawing Blankets can be a really big help.

 

image-ground-thawing-blanketsFrom Grave Digging to Concrete Prep

Whether you’re laying concrete or preparing a funeral plot, our ground thawing blankets can make the process a whole lot easier. Powerblanket Ground Thawing blankets help to thaw frozen ground prior to digging. And in the case of preparing ground for a funeral in the winter or early spring, ground-thawing assistance can make the process run a lot smoother. Here are some words from a satisfied customer who used our ground thawing blankets for their business:

“Your blankets are absolutely excellent. Thanks to Powerblanket, we were able to quickly thaw the ground and complete our job. In fact, we estimate a savings of 10 hours per site, equaling a savings of $5,000 already. Calculating this into our thousands of sites, the savings are huge! We are excited about the time and money Powerblanket has saved us and look forward to future savings.”

Our patented blend of technology and our use of durable materials enable us to deliver high watt density throughout the entire area of application, making ground thawing through electrical heat transfer safe and highly efficient. So when it comes to preparing a plot for burial, use our ground thawing blankets to make the task much easier.

 

Why Powerblanket® Ground Thawing Blankets?

  • High watt density thaws frozen ground fast
  • Quickly remove frost prior to digging
  • Melt snow and ice from ground prior to digging
  • Easily installed and removed
  • Easily transportable
  • Safe and certified to national safety standards

 

Some Things to Remember

Remember that thawing ground goes a lot faster if you first manually remove as much snow and ice as you can.  If you have a foot of snow, remove it all, then apply the blankets.  A foot of snow can add a day to the process if not removed first.

Secondly, thawing frozen ground through a layer of grass can be problematic.  The grass tends to hold the blanket up and away from the frozen ground, making the thawing process much longer than it would be with bare ground.  If a Powerblanket ground thawing blanket is left in place too long, it WILL kill the turf. So if keeping the turf healthy and intact is the goal, then don’t use a ground thawing blanket. However, if you’re trying to thaw the ground for digging purposes, then remove the grass first.

 

button (16)