Two identical grain storage buildings in South Dakota (one in Roscoe, the other in Andover) were experiencing concrete foundation settlement. The buildings each store 1.5 million bushels of grain, are 600 feet long by 135 feet wide, and feature a series of tunnels beneath them to assist with grain conveyance and to provide ventilation. The foundation slabs for both buildings were eight-inch reinforced 3,000 psi concrete. URETEK was contacted to help level the concrete foundations and stabilize the underlying soils, with a focus at each building on a 12-foot by 600-foot section on either side of an aeration tunnel that had settled and cracked.
During the first 18 months of service, the Roscoe warehouse averaged 1.5 inches of foundation settlement, while the Andover warehouse averaged 0.75 inches. The maximum settlement observed was three inches at the Roscoe location. Soil testing showed no specific soil anomalies at depth at either site. However, drilling revealed that soils at the Roscoe location were highly saturated while Andover’s soil moisture content was only slightly above normal. It was learned that during construction of the facilities, both locations experienced a major rain event and an accumulation of snow prior to installation of the roof systems. The runoff from both events likely seeped through the joints where the tunnels and slabs met causing erosion along the exterior of the tunnels and saturating the subsoils.
The URETEK Deep Injection® (UDI) process was a natural fit to lift and stabilize the storage facilities because of its hydro-insensitive properties and high weight-bearing capacity. Because both facilities run year-round, repairs had to be made quickly during a scheduled outage window. URETEK crews rose to the challenge. The team averaged over 2,000 square feet of UDI foundation lifting per day at the Roscoe location and approximately 3,000 square feet per day at Andover. At Roscoe, soybeans were stored in one half of the facility while the crew was on site. Once one side of the floor was lifted, the beans were transferred to the completed area so that work could continue on the other half of the floor. At Andover, all repairs were completed in just five days and the client began restocking the storage facility within three hours of URETEK’s departure. Both facilities were back online immediately after the work was completed.
URETEK stabilized, lifted, and returned to service 28,800 square feet of storage facility in a matter of a few days at each site, exceeding the customer’s need for speed and efficiency. URETEK’s zero-excavation concrete leveling solution allowed the grain storage facility to quickly and effectively repair the settlement problem, restore original design capability, and greatly reduce production downtime. The facility is now better able to accommodate high-volume grain loads without any hesitation.
URETEK Deep Injection® (UDI)
Widely referenced throughout our industry, UDI involves the injection of structural polymer into base and subgrade soils to increase the load bearing capacity. This is achieved by injecting the polymer through small holes drilled directly through the pavement structure to depths determined by site-specific analysis. Our URETEK 486 Star® material flows easily into voids and weak zones within the soil mass below. Through a controlled chemical reaction, the expanding polymer compacts surrounding soils and applies a controlled pressure on targeted areas of the affected pavement above. If needed, a multi-injection design plan is utilized to gently return the pavement to its original grade. The composite material quickly cures into a strong, dimensionally stable, and water-resistant geo-material, providing years of reliable service.
URETEK 486 Star®
URETEK 486 Star® polymer is a two-component, high-density, expanding thermoset polyurethane system. It was developed to be the ideal solution for under-sealing, void filling, lifting of settled pavement, stabilization and stiffening of weak soils, and for encapsulating and sealing buried infrastructure. URETEK 486 Star® is environmentally inert, non-toxic, and resists underground water erosion or weakening due to its industry-leading hydrophobic properties.