Location: Chicago, Illinois
Award: Durability
Project Team
Owner: The Prime Group General Contractor: W.E. O’Neil Construction
Contractor: McHugh Concrete Construction, Inc
Architect: Lucien Lagrange Studio
Engineer: WSP
Concrete: Oremus Material Slag Cement: Skyway Cement Company
Located in Chicago, IL, USA, the RIU Hotel Chicago is a 273,000 ft2 (25,300 m2), 28-story cast-in-place concrete structure. Completed in December 2023, the superstructure was built with 14,200 yd3 (10,900 m3) of concrete, 1200 tons (1088 tonnes) of reinforcing bar, and 125 tons (113 tonnes) of post-tensioning. The structure is distinctive from neighboring buildings—rather than a standard brick and glass curtainwall system, RIU Hotel Chicago is enclosed with architectural concrete.
Slag cement helped to achieve a high-strength concrete with a smooth, uniform finish for the exposed concrete exterior. Achieving the architectural vision for the exterior of the building was significantly important to ensure the overall success of the project. Through careful and strategic planning, the McHugh Concrete team partnered with Doka to provide special formwork to achieve the architectural reveals in the concrete. Fiberglass reveals, attached to the formwork in a pattern designed to mimic a brick façade, resulted in the desired brick-like appearance after the forms were stripped.
Slag cement helped improve the pumpability and reduce the permeability of the concrete, resulting in a surface that is expected to last up to 30 years longer than conventional concrete. The concrete’s high solar reflectance helps to keep the building cooler in the summer by reflecting sunlight, reducing HVAC energy demands and minimizing the heat island effect of the surrounding area.
RIU Hotel Chicago is located at the intersection of Michigan Avenue and Ontario Street in the city’s Streeterville neighborhood. The project’s logistics were challenging, as the site had zero laydown space for materials. Strategic planning of deliveries and storage of materials at the McHugh Concrete equipment yard ensured the structure’s successful completion. The team also coordinated the shutdown of Ontario Street for the McHugh Concrete ironworkers to safely dismantle the tower crane.
The concrete mixtures achieved high strength in 18 hours for post-tensioned applications, which aided in maintaining the typical placement cycles and efficient high-rise schedule. This concrete mixture also helped to lower the embodied carbon used to build the structure.
Application Type
% Slag Cement Replacement | Up to 45%, depending on application |
% Portland Cement | |
% Portland Limestone Cement | As low as 55%, depending on application |
% Other SCM (if applicable) | |
Aggregate | 3⁄4” stone and manufactured sand |
Water/cement ratio | 0.30-0.45 |
28-day strengths | 2,500-6,000 psi, depending on application |
56-day strengths | 6,000-10,000 psi, depending on application |
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