Challenge

The Parks Board of Clarksburg, West Virginia commissioned the repair of concrete landings at “The Amp”, the community’s 2,000 seat amphitheater. Three feet by six feet poured concrete landings are located at the seating elevations along each of the three access stairways. Twenty-three of these landings had settled as much as three inches, creating trip hazards that increased risk of potential injury to patrons and the City’s exposure to claims. The Parks Board specified that the concrete be lifted back toward level, voids be filled beneath the slabs, and the entire project be completed in less than two weeks to ensure the amphitheater was ready for the thousands of guests attending the Fourth of July concert. Removal and replacement of the slabs was considered, but ultimately dismissed due to the limited time available and the idea that there would then be different colors of concrete along the stairs.

Solution

The Parks Board selected PolyLEVEL™ polyurethane injection to fill the voids and lift the landings back toward their original elevations. PolyLEVEL™ is a two-part urethane that expands into a rigid foam used to fill voids, stabilize slabs and lift concrete. Once injected through small 5/8-inch drilled “ports” in a slab or surface, a chemical reaction converts the liquid urethane components to a strong, rapidly-setting foam material. In its foam state, PolyLEVEL™ is relatively light, weighing two to six pounds per cubicfoot (pcf). Other void-filling or lifting materials can weigh upwards of 120 pcf, adding significant weight to supporting soils or base materials and potentially contributing to further settlement. With a typical in-place compressive strength of at least 75 pounds per square inch (psi), PolyLEVEL™ 250 was proposed to support the landings. Foundation Supportworks® of West Virginia prepared the work area by first cutting through joints with a concrete saw to eliminate friction and prevent binding between the slabs and adjacent steps. A total of 150 pounds of PolyLEVEL™ 250 was injected through 65 ports. The expanding PolyLEVEL™ foam filled the voids and lifted the 23 concrete landings back toward level to minimize or eliminate trip hazards. The entire project was completed in less than four hours.

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Project Summary

Certified PolyLEVEL™ Installer: Foundation Supportworks® of West Virginia

Product Installed: PolyLEVEL™ 250, High Density Spray Polyurethane

Product Characteristics (PL250): 75 psi Compressive Strength, Shear Strength, 29: 1 Expansion Rate, 4 pcf Typical In-Place Density