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2016WinterShotcreteEMag

Corporate Member Profile Preload Prestressed Concrete Tanks In the 1930s, engineers at Preload embarked on a vision which would literally revolutionize the storage tank industry. The idea was simple: create a storage tank structure that would stand the test of time and provide excellent service for decades. One that would not require coatings and thus would be virtually maintenance-free. One that could be used for many applications across many different industries. One that would be economically priced when compared to other types of storage tank structures commonly in use at that time. Preload engineers continued to research various means to accomplish their goal and a few years later, the engineering research was complete and the solution was clear. Shotcrete and concrete would be used to construct the tank to ensure long-term durability and eliminate costly maintenance. The tank wall would be prestressed using a solid wire manufactured from highstrength steel to put it into permanent compression to eliminate cracking and long-term durability problems. The prestressing wire would be placed with a new invention that would allow precise, economical, and safe tensioning to produce a reliable tank structure. Shotcrete would prove to be one of the most important materials, as it provided a sure means of encasing the highstrength wires and bonding them to the wall to guarantee corrosion-free service and reliable performance. Last but not least, Preload would perform the work with specialized engineers and trained construction professionals to ensure a level of quality that had never before been applied to concrete storage tank structures. In doing so, the best properties of concrete, shotcrete, and steel were used and the industry of wire-wrapped prestressed concrete tanks was born. Preload’s invention was one of the first examples of sustainable development in modern construction history. Compared to conventional cast-in-place concrete tank walls, quantities of concrete and steel in wire-wrapped tank walls were reduced by over 50% as a result of the efficient use of the materials. Over 85 years later, the benefits of the invention of wire-wrapped prestressed concrete tanks by Preload continue to have a lasting impact on communities and industries across the nation and around the world. The hallmarks of Preload’s invention continue to be enjoyed and appreciated by thousands today, as wire-wrapped prestressed concrete tanks provide durable, low-maintenance storage for the world’s most precious natural resources, including water, reuse water, thermal energy storage, and liquefied natural gas. Preload tanks also serve to protect the environment when they are used to treat and store wastewater, storm water, reuse water, and process water for industrial applications. 85 Years of Exceptional Quality Design and Construction Today, Preload continues to be the industry leader in the design and construction of wirewrapped prestressed concrete tank structures. With over 3500 structures built to date for all types of liquid storage, including water, reuse water, wastewater treatment, storm water, industrial process applications, thermal energy storage, and liquefied natural gas, Preload continues to lead the way in the design and construction of these structures in the United States and around the world. Preload wire-wrapped prestressed concrete storage tanks are virtually maintenance- Fig. 1: Early prestressed shotcrete storage tank—circa 1936—in continuous maintenancefree service for more than 70 years 72 Shotcrete • Winter 2016


2016WinterShotcreteEMag
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