When you're processing 700,000 tons of solid waste a year like the Southeastern Public Service Authority in Portsmouth, Va., the last thing you want to do is shut down operations to fix a cracked and crumbling floor.
But when the inevitable can no longer be postponed, you want that repair to be as fast as possible.
“We run very big CAT 980G loaders on these floors,” says Jim McMichael, waste engineering manager for the authority's refuse-derived fuel processing plant. “Because we dispose of all the trash for six cities and two counties in Virginia, downtime is very precious to us.”
Like virtually all solid waste operations, the floors of the authority's transfer stations are concrete. But even with a 1-foot structural slab, heavy front-end loaders and tractors, metal, and glass can wear away up to 1 inch of floor every year in operations that handle more than 500 tons/day. Facilities that process 2,000 tons or more a day may lose even more.
Loathe to endure the two weeks required for surface preparation, removing the old concrete, putting down a bonding agent, placing fresh concrete, and letting it cure for seven days, McMichael is patching floors with a combination of recycled iron shavings and cement called Delta Top. The product's installer, Delta Pacific–Structural Preservation Systems (SPS), says it provides four to eight times the impact and abrasion resistance of concrete.
Most recently, McMichael specified the product for a 10,000-square-foot repair. Because the product allows facilities to continue operating while the worn part of the floor is being replaced, one floor surface can be repaired while another is still being used.
“You don't have to rip up the entire floor; it can be installed right on top of the existing concrete,” says Jim Andrews, general manager of Delta Pacific–SPS's heavy duty flooring division. “We prepare the area to be overlaid and bond the new topping to the base slab. In most cases, this can be done in one weekend. If we pour on Saturday, you're typically back rolling on Monday.”
Having completed his third project using Delta Top, McMichael feels the additional investment is justified by not having to shut down.
“For smaller operations, such as those handling 25 tons/day, an iron aggregate floor might not be as competitive as other options, and it might not make economic sense,” says Andrews. “But operations that process 500 or more tons/day would see a financial benefit.”
Other factors in your cost-benefit calculation should include: