Round-the-clock pouring started at 4:47 p.m. Saturday with 208 trucks making more than 2,100 trips and pouring 82 million pounds of concrete during an 18 1/2-hour period, said Sean Rossall, a spokesman for the project building a skyscraper called the New Wilshire Grand. Ultimately, 21,200 cubic yards of concrete were poured by 11:30 a.m. Sunday, beating the existing record of 21,000 cubic yards set by The Venetian hotel in Las Vegas in 1999, Guinness World Records adjudicator Michael Empric said.
"We just wrapped up, and we broke the world record," Rossall said minutes after blaring horns officially announced the last pour.
Empric monitored the pour overnight by smartphone before meeting with contractors and engineers Sunday to check their final numbers. Empric, who had just finished judging a successful Valentine's Day effort to set the record for the most people feeding each other simultaneously, said he has learned a lot about concrete and the challenges of such a pour.
"If they don't cool the concrete as it's poured, it'll go into this thermal reaction and crack," Empric said.
Each truck made 10 to 14 concrete drops, traveling through the night between eight different concrete plants within a 20-mile radius, Rossall said. The first batch of concrete poured onto the site came from a plant in Vernon that poured the first concrete in Southern California ever, Rossall said.
Once finished, the skyscraper will soar 1,100 feet, making it the tallest structure west of the Mississippi River. It will boast a 900-room hotel, convention space and offices. There also will be an outdoor terrace and a swimming pool on the 73rd floor.
It's scheduled to be completed in 2016 and to open in 2017.
The New Wilshire Grand project, developed by Korean Air, is estimated to cost more than $1 billion and has been a huge undertaking.
For the past several months, crews have prepared the site by digging an 18-foot-deep pit and lining it with 7 million pounds of reinforcing steel.
Because the concrete must be poured within 90 minutes of being mixed, trucks had to arrive on time. In case of freeway jams, alternate routes were mapped. Rossall said traffic had a minimal impact on the pouring, which had been scheduled to last 20 hours.
Rossall said the crews "double-planned and triple-planned" to ensure no disruptions.
The concrete now must "cure," or set and harden, over the next couple weeks.
"Once that's completed, we're going to start moving vertical on the building," Rossall said. "That's the next big milestone for us."