Western Specialty Contractors – Dallas, TX Branch proudly announces it has received a 2023 International Concrete Repair Institute (ICRI) Award of Excellence in the Special Projects Category for its repair/restoration of historic silos in McKinney, TX that would become the canvas for internationally-acclaimed Australian artist Guido van Helten’s U.S. silo series, “Monuments”. McKinney’s silo mural features painted images of local business owners, gatherings and neighbors that honor the city’s culture and past. Van Helten’s public art installations can also be seen in Minnesota, Iowa, Kansas and Arkansas.
Western’s branch representatives received the award on Oct. 17 during the ICRI 2023 Fall Convention in St. Pete Beach, FL. Additionally, Western’s Charlotte, NC Branch was also honored at the ceremony with an Award of Merit in the Special Projects Category for its tower modernization work at Bon Secours St. Francis Downtown Hospital in Greenville, SC.
ICRI conducts an awards program each year to honor and recognize outstanding projects in the concrete repair industry. Entries are received from around the world, and the winning projects are honored each year at the annual ICRI Awards Banquet at each ICRI Fall Convention.
“This was such as large scale and important restoration project, not only for the artist, but for the entire City of McKinney,” said Western Branch Manager Austin DeJohn. “We knew going into this project that these silos were not only a part of the town’s history, but they would also become the canvas for an unbelievable mural that would attract visitors from around the country. Our work would not only need to stand the test of time to preserve this historic structure, but it would also need to be restored in a way that the mural’s integrity would be protected as well. It was truly an amazing project and we were happy to have been a part of it and we thank the ICRI for recognizing our efforts.”
The McKinney project consisted of eight interconnected silos constructed circa 1927 as part of the Collin County Mill & Elevator Company. The mill closed in the 1970’s and the silos sat vacant for decades. The structures were contributing elements to the mill which was placed on the National Register of Historic Places in 1987. As part of on-going redevelopment of McKinney’s historic downtown, city officials desired to restore the silos to serve as a landmark and backdrop to their adjacent, new municipal complex.
Each silo is approximately 20-feet in diameter, 80-feet high and made of cast-in-place, 7-inch thick conventionally reinforced concrete walls and concrete roof slabs covered with built-up asphalt material.
The silos also featured a two-story, rectangular concrete structure, called a “doghouse”, that extended above the top of the two easternmost silos and was connected to a steel-frame structure with sheet metal siding and a roof that was centered over the remaining six silos.
Numerous cracks, delaminations and spalls were observed in the silos’ exterior walls mainly caused by insufficient concrete cover over horizontal steel straps used for reinforcement. The cantilevered edges of the silo roofs were observed to be in poor condition, with numerous areas of spalled concrete and exposed, corroded reinforcing steel. The exterior concrete walls of the doghouse were observed to be in very poor condition with extensive areas of spalled concrete and exposed, corroded reinforcing steel. The existing steel windows in the exterior walls were severely corroded and there were many visible signs of freeze thaw damage to the 6-8-inch-thick concrete walls. A steel frame had previously been installed to brace the deteriorating concrete walls and frame.
Based on the observations, testing and intended future use of the silos by the City of McKinney, Western was contracted to perform the following scope of work which started in February 2022 and was completed within eight months:
- Crack Repairs: To mitigate moisture intrusion into the concrete, cracks in the exterior concrete walls greater than 1/32-inch in width where the concrete was not delaminated were routed and sealed using a flexible polyurethane sealant. Approximately 100-feet of crack repairs were implemented.
- Concrete Delamination: Spalled and delaminated areas of concrete on the exterior concrete walls were removed, exposed steel straps were cleaned and coated with a zinc-rich, epoxy-based corrosion inhibitor. Close attention was paid, ensuring conformance with ICRI Guidelines regarding surface preparation and repair geometry. The silo walls were repaired using pre-packaged polymer-modified cementitious repair mortar with integral corrosion inhibitor. Approximately 380-cubic feet of partial depth concrete repairs were implemented.
- Roof Slab: The roof slab roofing membrane was found to contain asbestos and areas along the outer edges had to be abated to expose the concrete roof slabs for full assessment. Deteriorated areas of concrete slab forming the overhang were removed along with areas of deteriorated concrete on the silo walls immediately below the roof slab. Supplemental reinforcing steel was placed, anchored into the remaining roof slab with adhesive, and coated with a zinc-rich, epoxy-based corrosion inhibitor. The overhang and areas of wall repair were then formed and repaired with pump and placed concrete. The remaining sections of the asbestos-containing roof membrane were encapsulated with a liquid-applied, two-component epoxy primer/sealer.
- Roofing: Upon completion of the reconstruction of the roof overhangs, a liquid-applied, polyurethane roof membrane was installed to protect the concrete roof slabs from moisture penetration. This product encapsulated the remainder of the asbestos containing roof membrane, thus minimizing the need for hazardous material abatement.
- Roof Top Doghouse: Demolition of the doghouse had to be completed before the old machinery that was in the doghouse could be cut up and removed. Once the roof was cleared, the floor openings from the doghouse were covered with steel plates and a new roof access hatch was installed. Approximately 12-inches of the north and south concrete walls were left in place next to the steel beams which were located over the silo divider walls for the doghouse structure. These were retained and covered with roofing for future reconstruction of the doghouse. The opened east end of the roof top metal shed was infilled with metal wall panels completing the work on the silo roof.
- Cleaning: When repairs were completed the walls were power washed to remove dirt and biological material and PVC downspouts were installed so the artist could start work on the mural at the north and west elevations.
Supply issues and the unforeseen difficulties encountered during the demolition of the doghouse structure compressed the construction schedule. The main objective was to complete the north and west elevations first so as not to delay the artist from starting. Once the north and west face of the silos were completed, work continued on the roof and the rest of the silos while the artist was installing the mural. The mural was started in June 2022 and completed in August.