Remembering the Alamoby Peter van Niekerk
Editor's note: In our last issue, Peter van Niekerk provided a case study on joint sand stabilization that spared substantial rehabilitation at a major intersection in downtown Palm Springs, California. The following case study takes us to another desert location, Las Vegas, Nevada., where persistent winds eroded away the joint sand between concrete pavers that were incorrectly specified for the application.
After limited period of use, a 30,000 sf (3,000m2) vehicular areas of concrete pavers at an Alamo rental car facility at Las Vegas International Airport was closed to bus traffic. A local paver manufacturer hired me to inspect the project and recommend remedies. Upon inspection, the edge restraints and the base appeared to be adequate for the application. Distresses included missing joint sand that was eroded away by the strong desert winds. This resulted in tire traffic shifting the pavers some 10 to 12 in. (25 to 30cm). During their movement, they experienced much chipping and spalling. One of my main concerns was that 23/8 in. (60mm) pavers had been used instead of 31/8 in. (80mm) thick pavers that are recommended by ICPI for vehicular areas.
The cost implications of my recommendation to remove and replace the pavers with thicker units didn't sit well with the owner. The "he-said she-said" debate followed on the source of the problem. The architect claimed that the manufacturer misinformed him to use thinner pavers. The manufacturer denied this, making the point that none of their sales representatives had communicated this misinformation. The owners noted that no further money would be invested on the project. An impasse was at hand.
I was evaluating the performance of joint sand stabilizers on some mock-ups at a major theme park and the preliminary results were favorable. As a passing thought, however unorthodox, was to offered by me to the owner of the rental car facility: why not lift, clean, and reinstate the existing pavers and stabilize the joint sand. While it was a low-cost solution, the suggestion was given with some reluctance since the 23/8 in. (60mm) thick concrete pavers would remain instead of replacing them with thicker pavers. The thinner units could likely reduce the serviceable life of the pavement compared to replacing them with 31/8 in. (80mm) thick units.
While I don't endorse using thinner pavers in such applications, there was a possibility of at least buying some service life with joint sand stabilization. Most important, the lower-cost solution of stabilizing the sand between reinstated 23/8 in. (60mm) thick units would give back the owner's 30,000 sf (3,000m2) of pavement needed to operate his facility.
The impasse was broken when the contractor agreed to re-install the units at his cost and the owner agreed to pay for the stabilizer. Work commenced two weeks later and the area was lifted, reinstated, joints filled with sand and stabilized. The stabilization material was applied with a low-pressure sprayer and excess sealer was squeegeed into the joints to bind the sand. After 24 hours of curing, the area was opened to traffic. All were impressed with the immediate improvement in the strength of the surface. The sealer had the added benefit of keeping the pavers cleaner and enhancing their color.
These events occurred nearly three years ago and not a single unit has come loose since that time. The owners have not spent a dime on maintenance. Most importantly, the entire project has upheld the credibility and reputation of interlocking concrete pavements.