An annual overview and a look forward from the National Precast Concrete Association.

Lehigh Hanson implements an enterprise-wide arc flash compliance program

Prevent Cracks with Volume Stable Concrete. The University of Utah’s basketball team needed to avoid concrete shrinkage and curling if they were going to be able to feature high quality wood flooring in their practice facility. With PREVent-C and 4 lbs/CY macro fibers, the entire 14,000-square-foot concrete slab was poured continuously with no joints. The floor flatness and levelness numbers were twice as stringent as required by specifications and no grinding was needed.

After historic flooding to Fort Randall Dam, located in South Dakota, inspections made it clear there needed to be repairs toward the dam to promise long term stability. In order to reduce concrete shrinkage for such a large product, the owner chose to use PREVent-C admixture at a 5% dosage rate in their specialty concrete mix design. With 130,000 dowel anchors being required to be drilled into the concrete, PREVent-C would help the amount of strain it would create to the concrete.

Listed on the U.S. National Register of Historic Places, the Cathedral Church of St. Paul in Boston Massachusetts went through vigorous interior renovations to create long term stability for its patrons. With extreme winters on the east coast, there needed to be radiant heating tubing in the new concrete floor which becomes a challenge. With high-paste content and the need to place joints in the concrete - shrinkage cracking and curling would take place and result in floor damages. PREVent-C Shrinkage Reducing/Compensating admixture was used during the project resulting in a crack-free 7,000 square foot slab.

Around 40 years ago, the Rodgers Roads Bridge over I-95 was built in Wilmington, Delaware. In order to preserve the bridge's structural integrity a maintenance project was due for long term stability. With a variety of rehabilitation options, a mill-and-overlay repair was scheduled to take place. Overlays come with hardships such as a high occurrence of shrinkage cracks that lead to freeze-thaw deterioration requiring additional maintenance in the future. PREVent-C500 shrinkage-reducing/compensating admixture was implemented and reduced shrinkage cracking by 85-90% that will lead to a longer life cycle.

Logan International Airport, located in Boston, Massachusetts, decided to increase parking capacity in their West Garage that provided an additional 2,050 parking spaces. The majority of the project utilized precast concrete with topping slabs in order to expedite the construction timeline. Using these applications caused concern for shrinkage cracking and early deterioration due to the harsh environment the garage was located in. PREVent-C admixture was chosen to provide a dual mechanism shrinkage-mitigation technology creating nearly a crack-free project.

The Intracoastal Way runs along the East Coast that helps shipping traffic in and out of the United States. In 2014, a seawall in Naples, Florida was due for reconstruction after years of salt water damage. Repair costs continued to increase with extensive cracking in the concrete and severe corrosion of the steel which caused spalling. The owner of the project was considering multiple options for a replacement wall. He wanted to ensure that the new structure would be able to withstand the salt water. The seawall needed to obtain a component that would create less cracks so the salt water would not come in contact with the concrete causing it to crack. The owner was confident that PREVent-C would give the structure a long life-cycle. After 3 months, there was no evidence of shrinkage cracks in the precast wall panels.

The Los Angeles Department of Water and Power began construction on two 55 MG enclosed reservoirs to protect drinking water that is currently stored in the open Silverlake and Ivanhoe reservoirs. The project needed to comply with EPA regulations which would hold a total water storage of 110 million gallons. The first reservoir (East) was completed in 2014 that led to shrinkage crack concerns, especially with the on-going drought in California . It was imperative that no water was lost due to leakage. When the first reservoir was completed, it resulted in 20,000 gallons of water loss per day. LADWP decided to use PREVent-C technology to improve their East Reservoir. They created roof deck slabs that included 5% PREVent C admixture that showed no shrinkage cracks. With great improvement, PREVent-C is being considered to be part of the West reservoir.

Liberty University in Lynchburg, Virginia built a new state-of-the-art natatorium that would measure up to 75,000 square feet. The facility is unique to the campus as it holds the largest diving platform in the United States and would be hosting USA swimming programs and national meets. Any crack in a pool is detrimental because a pool is meant to contain water and cracking can compromise the high-quality look and feel to it. PREVent-C provides controlled expansion resulting in volume stability creating 90 percent fewer cracks on average compared to standard concrete. Eight months after the project was completed, the results showed there were zero cracks.

The Glen Elder Dam and Spillway is located in Kansas and originally built in 1968. The dam serves many purposes in order to control flooding and create the Waconda Lake which is used for municipal and irrigation water. In 2010, extensive repair and renovations occurred due to freeze-thaw damage which promoted alkali- silica reaction. When new concrete was placed, extensive shrinkage cracking occurred within the first seven days. PREVent-C was chosen as a trial admixture to evaluate its effectiveness on shrinkage cracking. After approval by the US Bureau of Reclamation, the results were impressive. Cracks were completely prevented in two of the test slabs and about 90% reduced in the third slab.

Echo Dam is a 158-foot high earthfill structure on the Weber River in Summit County, Utah. Inspections concluded that modifications needed to be implemented with concerns of soil liquefying during a seismic event causing deformation of the aged spillway structure. Challenges arose before the project started such as the required low slump, long transport distance, and project timeline. The US Bureau of Reclamation chose PREVent C to reduce shrinkage cracks, based on successful field trials from the past. The use of PREVent-C can allow an increase in joint spacing, since the potential for concrete shrinkage cracks is greatly reduced.

In 2017, a large fire brought the interstate bridge 85 to collapse in Atlanta, Georgia. It became a transportation crisis for commuters and local residents so the Georgia DOT decided on accelerated construction techniques. The durability of bridge decks is severely compromised by shrinkage cracks which can lead to immediate access for water and deicing chemicals to the steel reinforcement and internal concrete. PREVent-C technology was selected to be used in an accelerated mix and a 3-day curing period versus a more standard 7-day curing period. When accelerated strength and minimal curing are used, cracking would be visible immediately following the end of curing. When the curing was removed from the 1-85 Bridge, there was no observance of cracking.

A bag of cement has a long journey behind it before it arrives at the building site. Between being quarried, processed, and supplied as the finished product, the material passes through many different stages. At each of these stages, special systems are in place to ensure the process is smooth, economical, and environmentally friendly: systems from BEUMER Group. Systems you can rely on – whether the job involves conveying, loading, or packaging cement.