On a cold blustery night in early December, 2004, Prairie Materials and Lindblad Construction combined efforts to pour a 4 ½ foot-thick reinforced mat slab for Corn Products International at its Bedford Park, Illinois manufacturing plant. The mat will provide the floor for a new high-sulfur-coal burning power plant that will support a boiler weighing more than 6 million pounds. The total dead weight that will rest on this slab will be over 12 million pounds.

Starting at midnight on December 3, 79 Prairie trucks from three separate yards (Yards #1, #3 and #33) began pouring the 22,800 square foot slab in a continuous pour that ended at 2:00 PM the next day. With ambient temperatures hovering around freezing, Prairie and Lindblad placed 3819 cubic yards of concrete using three Putzmeister Telebelts with reaches upwards of 105 feet. The goal was to place 9 cubic yards of concrete every 3 to 4 minutes from each belt. One ready-mix truck arrived on the jobsite every minute. Prairie maintained a dispatcher on site to keep traffic moving. QC personnel were onsite throughout the operation to insure consistent mixes from all the yards. “Prairie provided incredible support. They gave us everything we needed”, said Mark Stadalsky, Lindblad’s vice-president and project manager.

One of the biggest factors in designing mixes for mass concrete is that the hydration of cementitious materials causes temperatures in the center of a slab to be much higher than at its surface. This temperature differential can cause thermal cracking that would compromise the slab’s structural strength. To solve the problem, Gary Hall, QC technician for Prairie, says they designed the concrete mix to gain strength slowly, ensuring a low heat of hydration that would not exceed 130º F.

Logistics and safety are key issues in a mass pour, requiring meticulous coordination and organization. Since the plant was in constant operation, Corn Products opted for a single continuous pour over a weekend which would cause the least interruption to its operations. Lindblad held three key meetings with all of its vendors and subcontractors to plan the pour. Using aerial photos of the site, they worked through the whole process, from traffic control and conveyor placement to truck washout. As a result, the mat slab construction went smoothly, with no trucks damaged, no rejected loads and no injuries. And the finished slab has no cracks.

For more detailed information about this pour, see the February, 2005 article in Concrete Construction magazine.

Project Team:
Owner and General Contractor: Corn Products International, Westchester, Ill.
Engineer and Construction Manager: ESI Inc. of Tennessee, Kennesaw, Ga.
Concrete Contractor: Lindblad Construction, Joliet, Ill.
Concrete Conveyor Contractor: Ruane Construction Inc, Frankfort, Ill.
Reinforcing Steel Contractor: Gateway Erectors, Burnham, Ill.
Ready-Mix Supplier: Prairie Materials Sales, Bridgeview, Ill.