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2014SprShotcreteEMag

Industry News with The Conco Construction Companies (Conco), one of the was used. Special admixtures were used to ensure the largest pumping and belt companies in the United States, to temperature during the process of hydration didn’t exceed the coordinate the fleet of pumps, including 16 Putzmeister parameters designed for the mixture. Without those admixtures America, Inc. (Putzmeister) units, required for the record- the mat slab could have experienced thermal cracking and lower breaking, 21,189 yd3 (16,200 m3) mat pour. strength, which could impact the structural integrity of the To lay the foundation for the massive Wilshire Grand project, placing. Following the placement, a cure blanket and a thermal Turner and Conco devised a plan for the continuous 21,189 yd3 control system were put into place for 15 days. (16,200 m3) mat pour, which was located 79 to 95 ft (24 to 29 m) below street level. For the past several months, crews have prepared the site by digging a 20 ft (6 m) deep pit and lining it with 3700 tons (3360 tonnes) of reinforcing steel. During the massive pour, 12 Putzmeister truck-mounted concrete boom pumps ranging from 105 to 154 ft (32 to 47 m), two Putzmeister placing boom towers, and two Putzmeister trailer-mounted concrete pumps were strategically placed both inside and above the excavation. A total of 19 pumps were used for the pour. Six pumps at street level fed six pumps, including two Putzmeister MX 34-4 Placing Boom Towers, two 32-4- and a 36-4-Meter Truck Mounted Boom Pump, located deep in the excavation. Two Putzmeister BSA 14000 Trailer Pumps at ground level also relayed concrete into the pumps located inside the excavation. “We used Putzmeister equipment due to its durability and reliability,” said Michael Marchesano, Turner’s general superintendent. “With a continuous pour of this magnitude, you need to be able to count on your equipment to keep doing its job, even under demanding conditions.” The pour included 227 ready mix trucks making more than 2100 trips and pouring almost 39 million tons (35 million tonnes) of concrete during an 18-1/2 hour period. “Each truck made 10 to 14 concrete drops, traveling through the night between eight different concrete plants within a 30 km (19 mile) radius,” said Marchesano. “The first batch of concrete poured onto the site came from a plant in Vernon that poured the first concrete in Southern California ever.” The structural engineering team, Brandow & Johnston, elected a continuous pour to ensure the mat foundation would yield the maximum strengths. To guarantee the entire pour cured at the same rate, a special C40, 90-day mixture Shotcrete • Spring 2014 47


2014SprShotcreteEMag
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