Central Concrete, a business unit of U.S. Concrete, Inc. (NASDAQ-USCR), and the leader in delivering low-CO2 concrete to the San Francisco Bay Area, along with Jos. J. Albanese, a leading Bay Area concrete contractor, have developed several innovative concrete solutions to address the aggressive specifications required by the Zero Waste Energy Development Facility currently under construction in San Jose, California. Not only did Central Concrete and Jos. J. Albanese respond to a significant acceleration in the schedule, but they devised mixes and placement solutions that addressed the unique issues faced when working with waste materials. The project is being constructed by South Bay Construction, Inc., a leading construction firm, with headquarters in Campbell, California.

San Jose’s Zero Waste Energy Development Facility is targeted for completion in December 2013 and is expected to be the largest Dry Anaerobic Digestion (AD) facility in the United States. The Dry AD process converts high solid organic waste into green energy. It is projected that the plant will be capable of processing 90,000 tons of waste and producing up to 1.6 megawatts of renewable power. This is enough to power 2000 homes.

The key to building a plant of this type was making sure that the waste materials, such as methane gas, were properly contained. In addition, the team needed to address the corrosive nature of these waste products. In response to these challenges, Central Concrete evaluated several mix design combinations, both in the field and in the lab, to produce the desired performance. The result—dense, durable concrete mixes with tight, low shrinkage specifications. These mixes not only delivered the low water/cement ratio required, but the highly workable mixes allowed Jos. J. Albanese’s crew to place the concrete more efficiently, significantly helping them to meet the accelerated build schedule.

The Jos. J. Albanese team applied the Central Concrete mixes using a process called wet-mix shotcrete. This process involved pumping Central’s prepared concrete through a nozzle. Compressed air is then introduced and a “gun” delivers the concrete. Not only does this wet-mix process allow larger volumes to be placed in less time, but the ability to adjust the water allowed the team to meet the hardening properties required for the job. In addition, the teams from Central and Jos. J. Albanese poured and placed five extremely large mat floors in the very early hours of the morning to further assist the owner in accelerating the schedule.

“We chose to work with Jos. J Albanese and Central Concrete on this project for their knowledge in shotcrete applications and their ability to get it done”, said Jim Richley, Sr. Project Manager of South Bay Construction.