From warehouses to retail showcases to grocery stores and beyond, polyurea is a growing alternative to traditional epoxy, silicone, and polyurethane materials to fill and seal concrete slab control joints. Also called contraction joints by the American Concrete Institute, control joints are planned gaps that allow a crack to occur at a weakened area and helps avoid random cracking.
Concrete joints and their filler material endure many stresses during the slab curing period and service life, including continued shrinkage, traffic loads and thermal cycling. In these slabs, the saw-cut control joint edges require protection to avoid serious spalling and deterioration.
“Silicones and polyurethanes make good control joint sealants, but take at least 24 to 48 hours to fully cure and do not have the Shore hardness to be reliable joint fillers,” stated Gary Gutierrez, owner of American River Caulking Inc., a California-based sealant, caulking, waterproofing and membrane system contractor.
“Epoxies have the Shore hardness to be joint fillers and can cure in four to eight hours, but are not flexible or adhesive. They typically crack on both sides of the concrete, disbond prematurely and lack aesthetics. For new construction, remodels or remediation, we have found that polyureas protect concrete control joints better than epoxies, silicones and urethanes.”
He added, “Because polyureas cure so quickly, we can fill the joints during a lunch hour, and the concrete slab can be returned to service that afternoon. This helps with accelerated building timelines, where after the floor is done, you have racking, fork lifts and trucks coming in right after you.”
VersaFlex is one manufacturer of polyurea joint filler and sealant for a variety of U.S. industrial, commercial, and public markets. To meet the requirements of a variety of industries, the company provides polyurea systems—which are typically hand pumped or dispensed—in a range of formulations, including hard-wheel traffic compliant and IACSC-IARW compliant for cold storage use. The polyurea, which starts to set in about 90 seconds and is tack free in about 10 minutes, can be shaved flush with the floor and returned to service quickly.
“We have found that the Shore hardness of the polyurea holds up really well to heavy foot, cart and forklift traffic,” Gutierrez noted. # He added that polyurea’s ability to set and cure quickly not only optimizes end-user timelines, but contractor productivity. “Applying epoxy usually takes two applications, which would require my work crew to return the next day after curing. With rapid-curing polyurea, however, my crew can finish an application sooner.”
Warehouse, Freezer and Showroom Applications
Sid Arthur, owner of Fredonia, Wis.-based joint filling, caulking and spray foam contractor Sid’s Sealants, said he uses VersaFlex’s SL/88 polyurea on warehouse jobs. “For high-traffic warehouses and loading docks, forklift wheels and forks can hit the concrete slab control joints all too often, causing big spalls. SL/88 polyurea provides additional protection from heavy, hard-wheel dollies and forklift traffic.”
Sid’s Sealants has successfully used a similar polyurea formulation in freezers and cold storage as well.
“I had a freezer project where the customer specified epoxy joint filler, not realizing that it could take the epoxy weeks to cure due to the low temperature. We recommended and our customer chose SL/85 polyurea. This cures from -40° F to 130° F, can be returned to service in an hour, and is USDA/FSIS/CSA approved, so we turned over their project a day or two early.”
The performance formulated polyurea has also been used in grocery stores, retail showrooms, big box stores, and other venues, including polished concrete and decorative concrete applications.
According to Arthur, Sid’s Sealants has often taken advantage of the performance-formulated polyurea’s expanded color palette, which includes 68 standard colors and a wide variety of custom options. “In grocery stores and retail showrooms, we are often asked to accent the control joint with colors or patterns that complement the floor stain. I sometimes match the polyurea color with chunks of concrete that customers sent me as samples.”
In warehouses with specific staging areas for truck loading, Arthur has also inset some polyurea colors as line striping for safety or product staging.
“Since paint on the floor surface can be worn off by items dragged across it, some warehouse customers request polyurea inset line striping that is flush with the floor to permanently mark off certain areas,” Arthur noted.
When concrete control joint cracks or spalls are too large to be repaired with polyurea joint filler alone, Sid’s Sealants relies on a related product called Quick Mender. This concrete repair system by VersaFlex has a low viscosity and completely sets in about 10 minutes at 70°F, he said.
Quick Mender can be used to fill holes, spalls, and popouts, and to repair the broken shoulders of control and construction joints. It essentially “welds the concrete” by adhering to the concrete matrix, and filling the capillaries within the concrete. To increase strength, aggregate or concrete dust can be added to the quick mender slurry. This mix can match the color of almost any concrete slab.
For more information on the products mentioned here, visit versaflex.com.