Sharring experiences in urban infrastructure delivery.

Sidewalk Paver Foundations

By: Tom Davis Category: Sidewalk Features, Special Surfaces

Maintenance cost of pavers–concrete unit pavers and clay brick pavers–is directly related to the installation methodology in two ways. First is the support system below the pavers and second is the gaps between the pavers particularly when cutting them to fit around water meters, street light foundations, parking meters, etc.gualpaverinstall1.JPG

In downtown Houston we have installed pavers on cement stabilized sand (c-sand) and on concrete sub-slabs. As you would expect the sub-slab installations present fewer maintenance challenges. A c-sand installation’s value is directly related to the sub-grade preparation as the C-sand will not span soft spots like a concrete slab. Do not let anyone tell you it is only a lower strength concrete as there are many differences that begins with there being no reinforcing steel in c-sand.

The lesson here is when you compare the costs of the two support systems be sure to include requirements for sub-grade preparation in the c-sand column for replacing non-structural soil and through compaction and testing the compaction of that soil. That will increase the installation cost for the less expensive c-sand but if you do not then you must greatly increase allowances for long-term maintenance costs.

I believe you will find like we did that the best solution–although initial cost is higher–is the concrete sub-slab.

The second issue – The most frequent problem in my opinion occurs when pavers have to be saw cut to allow for edge of the curb, street light foundations and other structures.  Gaps at those cuts that are in greater than 1/4″ will be the first place the pavers start unraveling.  The cuts, when well done (see image on this page) do not allow anymore, or very little more, width of the sand than the standard gap between the pavers. Also avoid having water running across the pavers or ponding and cars splashing through as the sand is washed away and the pavers come apart.

The way to avoid or at least greatly reduce the failure at such locations include a poured-in-place concrete “skirt” whose edges line up with the coursing of the pavers so there are no angled saw cuts and wide sand-filled gaps.

This is a frequent problem around manhole frames in paver crosswalks where traffic and rain–or worse standing water near the gutter–causes the paver system to fail.


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