NJIT eNJoy House Pushes the Envelope for Precast Design Using PVA Fibers
This year, the U.S. Department of Energy presents its fifth Solar Decathlon, a competition that calls for green innovations in the construction of the future. For the first time in history, they will be judging a home constructed of precast concrete. One of the 20 teams participating in the competition was Team New Jersey, which included students and faculty from The State University of New Jersey (Rutgers) and New Jersey Institute of Technology (NJIT). The team designed the concrete panels to employ a wide variety of special conditions. Based on a beach house design, “eNJoy: A Generation house,” utilizes its architecture with solar panels and other integrated systems to function as a completely self-sustaining home.
Northeast Precast of Millville, NJ stepped up to sponsor and build THiN-Wall® panels for this project. “We do precast homes and commercial buildings every day,” says John Ruga, President of Northeast Precast, “but this was a unique opportunity to push the envelope and see what could be done with precast.” To address some of the new technological challenges of the design, John enlisted the help of Nycon. With the experience and knowledge of Nycon’s people, John was able to find the right combination of solutions that would help him reach his goals.
Northeast Precast needed to produce over 30 pieces of THiN-Wall® insulated precast panels, none of which were identical in shape, size or weight.
The specifics of the panel needed to be taken into consideration when figuring out which way to lift and handle each piece, not just once but a multitude of times. The house was first erected in late July, 2011 on NJIT campus in Newark, NJ for student and faculty evaluations, but would be moved to The National Mall in Washington D.C. for the 2011 Solar Decathlon. At the conclusion of the competition, it would be disassembled again and transported permanently to an unknown location near the Jersey Shore. Sustaining structural integrity and appearance of the concrete panels through the stresses of this plan added to the challenge that Northeast Precast and Nycon faced. They needed to find ways to reinforce, lift and handle these pieces safely.
Since the THiN-Wall® panels were constructed of 3-4 inches of poured concrete sandwiching a foam insulated core, there were few options for strengthening the concrete. This was necessary to prevent cracking during manufacture and particularly during lifting and handling. The solution reached by Nycon Corporation, was to add a blend of two types of PVA fibers to the concrete mix. The first fiber is a micro-fiber (RSC15) for crack resistance during production and curing, as well as providing toughness.
The second fiber is a macro-fiber (RF4000) for providing increased modulus of rupture and post-crack strength to the panels. Nycon showed John how PVA fiber technology can significantly reduce concrete cracking during the process. PVA can also add flexibility to the panels, reduce handling stress cracks and resist a wide variety of environmental attacks on concrete. As a result, the precast panels would hold their condition long past the competition.
- Chris Hindley