We are often asked how well Rubbersidewalks perform in cold climates. We wondered the same thing ourselves back in 2003, when all of our installations were on the temperate West coast. To find out, we sent Rubbersidewalks’ pavers to a nationally accredited lab, asked them to freeze the parts to 0 degrees Fahrenheit for four days, then take a sledge hammer to them. The lab had never had such a request. This wasn’t exactly a standard test. We wanted someone to try to destroy our product while it was frozen solid. The lab agreed to do it.

Some time later the test results came in. Despite their best efforts, the lab technicians had been unable to crack, break, indent, or even chip the frozen parts. They had repeated the experiment a number of times. They also dunked the frozen parts into hot water, for ten cycles. Again, no damage, or change in measurement.

Buoyed by our discovery, we installed Rubbersidewalks in New Rochelle, NY, where the winters are both harsh and cyclic. This was a perfect choice to examine Rubbersidewalks’ performance in freeze-thaw conditions.

Freeze Thaw Action

Called freeze-thaw or frost-heaves, it’s a result of the ground expanding when frozen. Actually, it’s the water in the earth that expands as it turns into ice crystals. A volume of water expands by 10% when frozen. Freeze-thaw action occurs mainly in environments where there is a lot of moisture, and temperatures fluctuate above and below freezing point. (Expanding ice crystals can exert pressures up to 21 megapascals (MPa) (2100 kgf/cm²) (3,046 psi) at -5 °F.

This pressure is higher than the resistance of adjacent hardscape, such as concrete, and causes it to starting breaking.
Making matters worse, when the ice thaws, water flows further into the fractures. When the temperature drops below freezing and the water freezes again, the ice enlarges the cracks even further. Ultimately, the concrete can shatter.
Throughout cold climates, spring brings budding leaves, chirping birds, and miles of broken concrete.

Concrete is likely to break; Rubbersidewalks is guaranteed not to break.

Elongation

Elongation is a term that describes a material’s ability to expand and contract. Concrete has zero elongation. Another common term is resilience, meaning ’give’. Concrete is 100% brittle with zero ‘give’. What makes it such an effective and durable building material makes it a fragile material as a cold climate sidewalk.

Rubbersidewalks has significant elongation and resilience. Both the tire rubber and the polyurethane resin which binds the rubber particles together expand and contract without any damage to the material itself. Also, Rubbersidewalks is densely compressed and contains no air or water. As a result, there are no water molecules within the material to crystallize.

Lab Reports

• Freeze-Thaw ASTM C 1026: Product exposed to 15 cycles of freeze-thaw at 0 Degrees for 90 days. No change. No facial defects. No signs of crazing, chipping, spailing, or cracking.
  
• Freezing Impact Test: Rubbersidewalks, at 0 degrees F for 48 hours, was subjected to measurement tests. Change in measurement was negligible.
  
• Rubbersidewalks at 0 degrees F for 48 hours were subjected to repeated impact testing. Samples exhibited no signs of crazing, chipping, spailing, or cracks by inspection.

Modularity

Concrete is monolithic. Even with joint seams, concrete cannot sustain the 5 -10% sub-base expansion without cracking or buckling. Rubbersidewalks is modular, with interlocked 1/8” seams. Rubbersidewalks ‘floats’ on top of the sub-base and can rise and fall with the atmospheric changes. If a paver remains upraised after the ‘freeze-thaw season’, it can usually be tamped back down. Occasionally, some sub base regrading is needed.

Other Winter Considerations

We are often asked about how Rubbersidewalks stand up to shoveling and snow plowing. New Rochelle was a great real-life test to answer this question.

Sutton Manor is a street lined with beautiful Linden trees, trees that had broken the sidewalk. People no longer walked on the sidewalks, but in the street. Complaints abounded but no one was willing to risk the welfare of their Lindens. Jim Maxwell, then Public Works Commissioner of New Rochelle, NY, sought out Rubbersidewalks as a solution.

When Rubbersidewalks were installed in September 2004, not one tree root was cut, trimmed or disturbed. In some areas we elevated the sub-base to ‘ramp over’ the roots and in one place we notched the bottom of the pavers to fit over roots that rose above grade.

The sidewalks were installed in front of two homes. One belonged to the revered actress Frances Sternhagen; the other to a retired attorney who made it his mission to put Rubbersidewalks ‘to the test’. Throughout the first two winters he shoveled, doused the site with salt and magnesium chloride, and treated the sidewalks ‘just like concrete.’

At the end of each season, their existing concrete sidewalks were in even worse shape than before. Rubbersidewalks were undamaged and unchanged. Rubbersidewalks had passed the test.

Product Information

• Salt/Chloride ASTM B117: Product exposed for 24 hours. No change in surface; no stain or residue
• Magnesium Chloride: Product soaked in saturated solution, removed and allowed to dry. No change in surface; no stain or residue

Installation in New Rochelle, NY

One year after installation, James Maxwell sent us a letter:

“Our Rubbersidewalks installation, completed last summer, came through with flying colors. None of the sections heaved or were damaged or discolored by the action of snow and ice control materials, or the action of snow blowers or snow shovels. The contractor performing the work used two or three bases types of materials (including stone dust) on which to set the blocks. Having gone through a winter, one base appears to have worked as well as the others.

The neighborhood in which the pilot project was done has a long history of sidewalk vs. tree issues. The two homeowners who front on the installation were extremely receptive to our efforts to find a solution to the tree/concrete conflict. We realize that a single year is not conclusive as to the longevity or durability of the product, but the potential is certainly there.

The cost for the pilot project was $8,400 for 125 l.f. of walk, 4 feet wide or about $16.80 per square foot. Our bid price for concrete sidewalk in 2005 is about $8.00 per square foot. A significant contributor to the cost was shipping this small amount of material from southern California. That coupled with this being a first for the contractor, and the extra effort associated with a "pilot project" added to the cost.”

Two years later, we received an email from James Maxwell, Former Commissioner, on March 15, 2006 regarding the project completed in New Rochelle, NY on September 15, 2004:
“The Rubbersidewalks have stood up well to the second winter with no discoloration from deicers or gouging from shovels, equipment. I noted some minor movement in a few individual pieces which may be due to frost still being in the ground. All in all, the product looks good.”

Another email from James Maxwell on August 22, 2006:
“The experience through the first winter here was that the product was no more slippery than concrete. Residents stated that the product was "easier on the feet". The installation here was in a residential area. ”

Sub-Zero

Recently we have been contacted about the performance of Rubbersidewalks in sub-zero temperatures. We went back to our sledge hammering lab and asked them to perform the same tests at 35 degrees below zero. Once again, the tests were conclusive: no damage, no indentation, no cracking and no chipping.

Rubbersidewalks was developed to be installed near trees and to allow the maintenance and preservation of the urban forest. It could just as well have been created to eliminate the problem of broken sidewalks in cold climates. We now have several successful installations in cold climates, including Garden City, Idaho; Hoboken, NJ; and Kelowna, British Columbia.