Type III Tank Walls – The Superior Choice in Prestressed Concrete Tanks
The Type III tank wall represents an innovation in prestressed concrete tank design and construction methods. PRELOAD’s Type III tanks provide maximum quality control during construction and greater durability. Our advanced methods for precasting wall panels and unequaled level of quality control make a Type III design the best option.
Type III tank wall panels are precast by the PRELOAD Team on-site and shaped to the proper curvature of the tank radius. Panels are constructed in casting beds and then stack-cast in an efficient assembly line process.
A steel diaphragm is used as the bottom form in fabricating each panel. The steel diaphragm is vertically ribbed with reentrant channels, providing a mechanical keyway anchorage to the concrete. The individual diaphragm sheets are mechanically lock-seamed. This process, invented by PRELOAD, produces an impervious watertight membrane throughout the entire wall area.
Next, side forms are positioned to form the edges of the panels, vertical reinforcing and lifting inserts are placed, and the concrete is cast and finished. As the concrete is cast, the thickness and cover over the diaphragm and reinforcing steel are positively controlled by the side form system. This process ensures a minimum of 4” of densely consolidated concrete cover over the steel diaphragm and proper cover over the reinforcing steel. Each panel is then cured in a high-humidity environment.
Once all wall panels are cast, the individual panels are rotated vertically and erected along the perimeter tank footing. The panels are then temporarily braced as the wall construction continues to assure safe construction in nearly any weather condition. The diaphragm is then joined together and joints between the erected panels are filled with shotcrete or concrete. Once the wall construction is complete, the circumferential single wire prestressing is applied.
If required, PRELOAD can embed inserts to support internal tank accessories. Wall sleeve penetrations that accommodate permanent manholes and through-the-wall piping are made watertight by sealing them to the steel diaphragm.