Yesterday I met with Al Martin, a UNILOCK sales representative for North America's largest brick paver manufacturer. We were discussing the challenges that the climate in southeast Michigan presents for interlocking brick pavers and modular retaining walls.
We both agree that our frequent "freeze thaw cycles" , the cycle of the ground freezing and thawing during the winter months, creates a lot of paving damage. It has been no secrete that the roads & highways in the Detroit area exhibit these damages like no other metropolitan area in the country, with Chicago a close second. I would like to comment on the effects of sub grade frost on pavements.
People enjoy the warmer weather here in Michigan during winter month's, but like most good things, there is always a price. When the ground freezes, water or moisture does not trickle down through the water table. Typically, in the Detroit area the average frozen ground depth is 3 feet. This is the reason footings for deck posts or masonry walls must be a minimum of 3.5 feet so the frost does not get below. When the top of this frozen ground starts to "thaw" due to warm weather, it becomes mushy & permeable. The soil below brick pavers, concrete, and asphalt becomes unstable and falters from loads (traffic) and voids in the subsoil. To add more salt (no pun intended) to the wound, it refreezes and traps more moisture between the frozen ground below and the surface. This freeze thaw cycle creates tremendous stress on any pavement by heaving and contracting.
It is not unusual for the Detroit and Chicago areas to experience over 30 freeze thaw cycles during the winter months (Dec thru Mar). This is probably the equivalent of 5 winter frosts versus 1 for a northern city like Minnesota. Many municipalities try to reduce the damaging effects of frost thawing by imposing "Frost Laws". These laws typically reduce the weight allowed by trucks to haul by 50%.
This background leads us to the the conversation I had with Al Martin on brick pavers & retaining walls. It is obvious why UNILOCK locates most of its brick paver manufacturing plants in Chicago, Detroit, Cleveland, New York, Ontario Canada, Toronto, etc.. . These cities fall in what I call the Frost Belt. Interlocking Brick Pavers and Modular Retaining Walls are the most economical and functional pavement for the "frost belt" over time. Repairs of brick pavers is much more economical than repairs of stamped concrete or asphalt. Over 60 years of paving stone experience & feedback has proved this throughout Europe, Australia, and North America.
Many of my clients blame their brick paver repairs on poor installation and this is not always true. Often I do see brick paver patios, sidewalks, and driveways that were poorly designed and installed. The first thing I point out to them is how many times in the last 15 years did the County or State redo that stretch of highway nearby. Usually, it has been redone twice so that is 3 different pavements, sometimes 3ft thick of concrete, that have been totally removed and replaced on average 5-6 years.
Brick pavers and retaining walls that are properly monitored and maintained will out perform any wood deck, stamped concrete or ashalt pavement. Whether you perform brick paver maintenance yourself or use a professional, you can enjoy the financial and aesthic value of paving stones for a lifetime!