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Case Study: Improving Concrete Cooling for Chicago’s 75th Street Corridor Improvement Project

Granite Construction and EquipmentShare collaborated to enhance concrete cooling techniques for Chicago's vital infrastructure

July 1, 2024

Man in a hazard vest on a mobile concrete cooling plant circulates chilled water through piping to control curing temperatures.

Projects like the 75th Street Corridor Improvement Project (CIP) in Chicago highlight groundbreaking innovation in infrastructure development. The CIP was designed to enhance the efficiency and resilience of a pivotal freight and passenger rail in Chicago's vibrant South Side. The rail line, known as the Forest Hill Flyover, is a monumental 2-track rail flyover constructed of reinforced concrete. Entrusted with the realization of this long-term vision, Granite Construction Company (Granite) partnered with EquipmentShare to ensure cutting-edge solutions and the seamless execution of the project.

Challenges of Hot Weather Concreting

In the face of Chicago's scorching summer, Granite encountered a formidable challenge as they started the pouring of a mass concrete bridge. With temperatures soaring between 90-100 degrees Fahrenheit, the project swiftly transformed into a hot-weather concreting project, demanding meticulous control over curing temperatures for its success.

Concrete curing, an exothermal process, releases heat during its setting. Excessive heat can compromise durability and strength, leading to micro-fractures and reduced longevity in mass concrete structures, like bridges. Traditional methods of pre-cooling or post-cooling were essential to mitigate this issue for the CIP. Pre-cooling involved chilling the concrete aggregate or mixing water, while post-cooling employed embedded piping within the concrete through which chilled water circulated to dissipate heat.

Concrete Thermal Cooling Solution

Granite's approach was ingenious. They integrated ¾” cross-linked polyethylene (PEX) piping, commonly used in residential radiant floor heating, into the bridge structure. This piping, threaded through the rebar cages, facilitated concrete thermal cooling. However, there was a challenge in providing a reliable chilled water system to circulate through these embedded pipes. Here is where EquipmentShare's partnership proved invaluable. 

Designing a Mobile Concrete Cooling Plant

EquipmentShare's Advanced Solutions division crafts solutions for everyday, critical, and emergency projects by providing HVAC, power, fluid, and air compression solutions. The Advances Solutions team worked closely with Granite and devised a solution employing two separate cooling systems. These systems were mounted on trailers and offered mobility and adaptability crucial for successive pours along the bridge. They were sized carefully and one system accommodated up to 46 PEX pipes, while the other handled 24 PEX pipes. This technique ensured flexibility and efficiency tailored to varying pour locations.

The comprehensive system included supply and return piping, PEX pipe connection manifolds, and the chillers' integral pumping. Chillers are designed for optimal cooling and temperature management in large-scale applications. These are ideal for industrial processes, event spaces, and extensive commercial facilities. Flow control bypasses allowed adjustment of flow rates, optimizing cooling efficiency. A buffer/storage tank served multifunctional roles, smoothing chiller load, managing water expansion, and providing convenience during system operation.

Execution and Success

EquipmentShare's planning extended beyond design and assembly. Rigorous testing ensured flawless functionality before deployment. On-site setup, including water fill, pressure tests, and system startup, also occurred seamlessly in collaboration with Granite. Trailer generators ensured an uninterrupted power supply, completing the turnkey solution.

These efforts equipped Granite with an innovative solution, streamlining the construction of the corridor. EquipmentShare's dedication, from design inception to on-site execution, ensured operational excellence. Remote monitoring of generators facilitated proactive maintenance, guaranteeing uninterrupted operation. EquipmentShare's seamless breakdown and servicing underscored their commitment to excellence as the project drew to a close.

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About EquipmentShare

Founded in 2015 and headquartered in Columbia, Mo., EquipmentShare is a nationwide construction technology and equipment solutions provider dedicated to transforming the construction industry through innovative tools, platforms and data-driven insights. By empowering contractors, builders and equipment owners with its proprietary technology, T3, EquipmentShare aims to drive productivity, efficiency and collaboration across the construction sector. With a comprehensive suite of solutions that includes a fleet management platform, telematics devices and a best-in-class equipment rental marketplace, EquipmentShare continues to lead the industry in building the future of construction.