'Big pour' demands big planning

After thinking about the biggest concrete pour in his 34-year career for the better part of a month, Terry Swenson could picture the unfolding of the 19-hour project as a detailed movie.

He knew how far the pouring of 12 million pounds of concrete that's 2,800 cubic yards would be at 3 a.m.

on Saturday, precisely four hours after the marathon project began.

He could picture the clockwork arrival of concrete trucks, one every 2.1 minutes through the front gate of the IGT Knowledge Center under construction on the campus of the University of Nevada, Reno, campus.

And just in case anyone had questions, the concrete foreman for Q&D Construction detailed every step of the massive job in a 10-page, handwritten schedule he laid out one weekend.

Swenson's planning was so meticulous that the project, initially projected to run for 19 hours of continuous concrete pouring, wrapped up two hours early.

The project, which began at 11 a.m.

on Friday, May 5, and ran through the night, affected workers many miles from the UNR campus.

The work was scheduled for a weekend night, Swenson explained a few days ago, for a simple reason: In the current supercharged construction market, it was the only time that Cemex, the concrete supplier, had the resources to pull off the big job.

"The supplier had to dedicate every truck they had, along with both batch plants," Swenson said.

And while the concrete batch plants were filling a fleet of 38 trucks 20 were on the road, coming or going at any given moment more trucks were hauling aggregate from pits near Pyramid Lake and cement from the Cemex plant at Fernley.

Once the pour was set in motion, it couldn't stop without threatening the structural integrity of the building.

On that long night of pouring, Q&D teams set the slab and footings that will support five floors of books and a computerized retrieval system.

Jeff Sepahpour, a senior superintendent of Q&D who's working on the Knowledge Center project, said the company's team of estimators began worrying about the challenges of a 12-million-pound continuous pour as they calculated the company's bid on the $108 million project.

Among their big concerns: The heat generated by the chemical process that occurs when concrete cures, heat that can cause cracking.

Even after it won the job, Q&D hired a Texas consulting firm to look at the question.

The company's suggestion a different mix of chemicals in the concrete, the use of larger aggregate won agreement from builders, engineers and university officials after three weeks of discussion.

But on May 2 four days before the project was to be set in motion the plans changed.

The larger aggregate that was needed to reduce heating, engineers decided, wouldn't fit around some of the closely spaced steel rebar in part of the structure.

The answer: Use of smaller rocks in that portion of the pour and larger rock in the rest.

So the first 20 trucks that rolled up when the job began delivered concrete with small-sized aggregate, followed by about 300 more trucks through the night delivering concrete made with larger stones.

The final foot of the pad's depth, the finished floor of that portion of the Knowledge Center, was constructed with yet another type of concrete, this one including a fiber additive.

While the engineering issues were pounded out, Swenson put together his schedule.

He knew trucks could deliver 340 cubic yards of concrete an hour to four pumps.

He did some quick math and knew how far the project would progress in each hour.

He made scale models to figure where to position Acme Concrete Pumping units.

Q&D carpenters, meanwhile, were figuring out how to build one-sided forms that would support the weight of five-foot concrete footings.

The verdict on their work: None of the forms moved at all.

In the final days before the pour was to begin, Swenson ran a rehearsal for each of the 12 foremen who would oversee the 90 Q&D workers on the project.

Each of them learned what they'd be doing at each hour.

"People can get lost if they don't have a specific job to do," Swenson said.

And the foreman also was thinking about safety.

Night work demanded good light.

A defined route for trucks a one-way loop through the tight job site reduced the likelihood of collisions.

Workers had at least 10 hours off from their Friday shift before they returned to work, and some were on the big job for only eight hours.

No one was injured during the job.

Sepahpour, meanwhile, considered the worst cases.

What if a concrete plant was forced to shut down in the middle of the pour? He talked over options, none of them good, with civil engineers and developed contingency plans.

But the worst-case plans weren't needed.

Anything but.

At 3:14 a.m., a state inspector slid over to Sepahpour and expressed amazement that the job was precisely where Swenson had predicted.

Later in the day, crews began slicing 15 minutes from the schedule every hour.

"It went smoother than I ever thought it would," said Swenson, who retreated for a long nap broken only by occasional telephoned progress reports once the final truckload of cement was in place.