Carl Brahe
Keeping a sidewalk safe and passable can challenging in Colorado. One of the most common defects I find, in some areas of metro Denver, is shifted concrete that creates trip hazards and drainage problems. Concrete sidewalks are displaced by tree roots growing underneath or expanding/contracting clay.
In some cases the concrete can be leveled by mud jacking (pumping a compound underneath to lift it) or stabilized by chemicals that prevent clay from expanding. Most of the time it must be broken out and re-poured.
That’s an expensive and labor intensive project. New materials, and material uses, are constantly becoming available that change the way we build things. Simple ideas, like metal joist hangers, improve cost and quality of construction. Rubber sidewalks may provide this kind of innovation for walks and patios.
Rubber sidewalks come in pre-manufactured panels manufactured in California by Rubbersidwalks inc. They are made out of recycled tires and shipped ready to install. Manufactured only in California at this time, shipping costs can exceed product cost.
Installation is more expensive. The manufacture says the average total cost is $15/sq ft compared to $10 for concrete. The advantages come over the long term. Concrete may fail within 5 years around large trees and even quicker on expansive soils. Concrete must be torn out and replaced. Rubber sidewalks are estimated to last 20 years around big trees and can be maintained.
Rubber sidewalks come in sections, 2’ x 2’, or 2’ x 2.5’ and 1.875” thick. These reversible panels are laid on a prepared surface and tied together. If the ground swell or recedes, or if tree roots move the panels, they may be lifted and the ground beneath corrected.
Tree roots reach under concrete searching for water. The concrete blocks the flow of water from the surface creating dry zones that roots must cross to find moisture. These roots evolve into thick, large structures that lift and crack sidewalks and driveways.
Rubber sidewalks allow water to penetrate and flow into the soil below. Roots stay smaller, not having to travel under the sidewalk to bring back moisture. Water permeability might also cut down on damage from expansive soils by distributing the water more evenly, allowing more uniform expansion/contraction of the soil.
Rubber sidewalks are currently being tested in 60 cities around the country. They have proven durable in the coldest winter condition and the hottest summer weather our country offers. These sidewalks come in assorted shades and textures resembling concrete, granite or adobe.
Aesthetically, rubber has some advantages. It gives and is more comfortable for walking or running. Balls bounce nicely and chalk washes off easily. Ecologically, it is superior. Made from all recycled materials it is completely recycled at the end of its useful life. It can be maintained rather than replaced. Trees can be saved that would normally be cut because of interference with walks and drives.