NewUrbanStreets

In my opinion the key to a long-life concrete or brick unit paver surface–assuming the foundation structure is properly built–is re-sanding. As discussed in other articles at this blog the sand is the “glue” that “locks” the individual pavers together.

The sand, when wedged tightly in the narrow joint between the pavers, essentially “locks” the pavers together. When the sand migrates out of the joints then the paver can move. When they move more sand is loosened and washes away in the next rain and on and on. Soon the sand bed below is being pushed up into the joints; the paver falls unevenly to one side; the top edge presses against the adjacent paver that is also falling into what is now a low place in the sand bed; the pavers’ top edges spall, the paver is weakened, falls further, more spalling occurs and eventually the paver area is unraveling.  You now need to replace the pavers AND the sand. That requires more time in the street and some of your paver attic stock all adding up to more money spent.

The top photo here shows a crew of four workers replacing bricks that failed as described above. If you look closely they have a small vibrating compactor, a 2-cycle hand-held masonry saw and various hand tools. The 2-cycle saw can be used to cut the replacement bricks but is not ideal. A typical wet-cut, mounted, masonry saw would be much better providing a neater more precise cut and fewer bricks wasted. The crew also needs enough traffic control devices to direct traffic around the work area.

A very important part is the process is the vibrating compactor. You can replace the sand and sweep it in. But, only if the pavers are forcibly vibrated with the new sand in the gaps, more sand swept in and the process repeated several times will you achieve the restored surface you see in the bottom photo. Notice the uniform, level surface, completely filled gaps and, most importantly, tightly wedged in sand granules between the pavers.

I conclude with a photo of wet pavers where the empty gaps are easy to see. Looking closely you will note several pavers that are not level and the edges are pressing on its neighbor. At the very top you can see a paver where the corner has spalled. Clearly a worker with a bucket of clean sharp sand, a vibrator and a broom could stop this paver section from coming apart–although the sand below has already begun to migrate out as evidenced by the pavers being out of level. The lesson I gleaned from this is that resanding has to be done before a problem is clearly visible.