World's Largest Cement Plant

Holcim (US) Inc., Ste. Genevieve County, MO

Services

Design-build services to deliver slip formed silos, foundations and slab-on-grade, structural steel roof with cast-in-place concrete deck and all interior elevated discharge slabs, and precast inverted cones.

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All work was self performed by MC Industrial crews. Workers placed 80,000-cubic yards of concrete and 22.8 million pounds of rebar. At project completion, MC Industrial exceeded 850,000 man hours.

Challenges

• Working with design-build contractor and world-wide leader in slip-form technology, T.E. Ibberson of Minneapolis, MC Industrial needed to self perform concrete work on five different types of silos (15 total), placing 80,000-cubic yards of concrete and 22.8 million pounds of rebar.
• Eight of the silos, measuring 79-ft-diameter and 275-ft-tall, required the most reinforcement, post tensioning and embeds per cubic yard of concrete, the most yards-per-hour poured, the most difficult wall profiles and also the most complex deck design. Consequently, they required almost twice the manpower as any other slip.
• In the end, for 15 silos, there were a total of 80 “slip days equating to 306,000 total man hours. More than 80,000 cubic yards of concrete and 22 million pounds of rebar were used to complete the silos. Ten of the silos contain a post-tensioning system.
• To construct the inverted cone bin bottoms of the cement silos, 24 precast panels were installed to make the inverted cone. The panels were set on a perimeter ledge 60 feet above grade and then extended upwards to the center another 60 feet. These 32.5-ton panels were then hung by temporary tension rods in mid-air until all 24 were in place and joined together with concrete. The logistics of lowering the panels 215 feet down the inside of the silo and the precision required to set them while the crane operator was in the blind was extremely challenging. At the same time, workers needed to be in position to suspend and concrete the panels together.

Achievements

Complexity or uniqueness of construction
This project required slip form delivery, a common construction method for tall structures such as silos and towers. It involves a custom –built set of forms that are continuously moving (“slipping”) upward at a rate of approximately 10 inches per hour by means of jack rods and hydraulic jacks to extrude the structure. As the forms slip, rebar, post-tensioning and concrete are set in place between the forms 24 hours a day until the structure is completed.

Planning for success
To complete the slip form work safely and efficiently, this project required precise and extensive planning for all work activities. For example, before a slip could be executed, weeks of planning went into assembling the slip deck. Manpower access, on-deck lay down requirements, crane needs, etc., all were planned in detail. Mistakes would ultimately affect all aspects of the outcome and were unacceptable.

Surpassing quality expectations
To ensure quality construction, MC Industrial used 6,000 psi concrete that has an extremely tight range of slump and temperature for slip forming, in order to keep the slip forms moving at the proper rate of 10 inches to 12 inches per hour. The use of 75 kip rebar, which is a special order reinforcing, and the use of post tensioning in the silos, is somewhat unique.

Safety
During the 19-month duration of the project, MC Industrial self performed 850,000 man hours. The site operated under MSHA safety rules and regulations with a ZERO tolerance program concerning safety violations and infractions.

Results

Planning and execution paid off. Today, Holcim’s new plant features the largest single clinker production line anywhere in the world, with an annual cement capacity of four million metric tons (12,000 tons per day). 

_{Projects completed prior to 2005 were performed by McCarthy.}

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Honors & Awards

• St. Louis Chapter of American Concrete Council, Quality Concrete Award
  
• Post Tensioning Institute, Award of Excellence
  
• St. Louis Associated General Contractors, Keystone Award