Plum Point: Just Add Ice And Mix

Posted by on Dec 14, 2011 in News | 0 comments

Plum Point: Just Add Ice And Mix

Razorback Concrete team comes up with solution for the heat

Record heat in August didn’t stop construction of the new Plum Point Power Station in Osceola. Temperatures of more than 100 degrees can create problems for concrete work, but thanks to innovative ideas from Razorback Concrete, some outstanding teamwork, and a lot of ice, a solid foundation was laid for the massive coal-fired power facility.

Pouring concrete in extreme heat creates numerous problems that will undermine the quality of the finished product. This is especially true when the job is massive, like the Plum Point project. The Plum Point Power Station now under construction will provide electricity to more than 650,000 homes in the region. Commercial operation will begin in 2010.

As part of the construction effort, Engineers designed a concrete platform 13-feet thick to support a 465-feet chimney. The platform required more than 4700 cubic yards of ready-mix.

This was a very difficult concrete pour,

said Leroy Colley, the project superintendent for Zachry Construction.

But we had no problems. Razorback Concrete had a great team present and the pour went very well.

Curty Caviness, quality assurance manager for Razorback Concrete explains:

The concrete was poured in layers approximately one and a half feet thick. In high heat conditions the concrete will set too fast, so that the next layer does not properly consolidate with the previous layer. This creates what is called a cold joint. Concrete that sets too fast also is more prone to cracking.

To avoid these problems, Razorback technicians devised a plan to keep the ready-mix within the recommended temperature range so that it would cure at the proper rate. Their solution: massive amounts of ice.

The company discovered that FEMA, the Federal Emergency Management Agency, was planning to dispose of tons of ice left over from the Hurricane Katrina relief effort. Razorback Concrete interceded and convinced FEMA to sell the ice.

They were going to pay someone to get rid of it, so we asked if we could have it,

Tony Beard, an area manager for Razorback Concrete, explains:

The ice – more than 450,000 pounds – was delivered by truckloads in bags of various sizes, ranging from 16 to 22 pounds. The amount of ice needed for each load of ready-mix depended on the ambient temperature, and the temperature varied from the mid-80s to over 100 degrees, depending on the time of day.

A pour of this size has to be done continuously once you start, so we knew it would take approximately 24 hours to complete, explained Caviness.

We were constantly monitoring the temperature and running tests so that we could adjust the mix and keep it at a maximum temperature of 80 degrees. Keeping it at 80 degrees would allow the concrete to cure at the proper rate and give us the quality we wanted.”

As the temperature changed, so did the amount of ice required for each load. Crews were standing by at two different Razorback Concrete plants to calibrate the mix, break up the ice bags and load them into the mixer trucks. The water-to-cement ratio also had to be adjusted based on the amount of ice added to the load.

Three shifts were scheduled to keep the ready-mix rolling once the pour got underway. More than 50 mixer drivers were utilized, with one or more drivers from each of Razorback Concrete’s 17 locations. Workmen were able to pour approximately 240 cubic yards of concrete per hour during the first hours of the job.

I can’t say enough about the teamwork and cooperation that we got from everyone throughout the company. Randy Chandler and Michael McMinn were the dispatchers and they did an outstanding job. I was just very proud to be a part of this project.

said Beard.

This was one of the most technologically complex jobs we’ve ever done in my 29 years with the company. Everything had to be done correctly, and it was. It was truly a company-wide effort.

Remarked Caviness.

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