Stress Relief for Big Dams
Category: Hydroelectric Dam Machining
Method(s) Used: Wire Sawing
Location: Mactaquac Generating Station, New Brunswick, Canada
Evidence of distress in a concrete dam at a Canadian generating station called for swift action to maintain safe working operations. Investigations determined that the end pier of the dam spillway was cracked internally and the cause of the problem was identified as Alkali Aggregate Reaction (AAR). A contractor was needed that could create large vertical slots through the concrete structure quickly and cleanly.
Stress Relief for Big Dams
Our Work in Action
The Problem
Evidence of distress in a concrete dam at a Canadian generating station called for swift action to maintain safe working operations. Investigations determined that the end pier of the dam spillway was cracked internally and the cause of the problem was identified as Alkali Aggregate Reaction (AAR). A contractor was needed that could create large vertical slots through the concrete structure quickly and cleanly.
The Solution
In-Place Machining Company used a unique hydraulic-driven machine that was custom fabricated to feed 3.3-meter-long (10.8 feet) sections of aluminum tubing downward. The system is capable of plunging down to a depth of 33 meters (108.3 feet), but was only required to plunge 25 meters (82 feet) on this job. All cuts at Mactaquac were maintained using 15-millimeter-diameter (0.6-inch) electroplated diamond wire supplied by Norton Pro Diamond. This was a directional rubber-injected wire, providing added strength to the wire assembly and minimized the breakdown of the wire caused by concrete slurry. The wire was constructed with 40 beads per meter and a 4.9-millimeter (0.2-inch) base cable.
The Result
“Diamond wire sawing systems are ideal for making slots in mass concrete structures. Maintaining slots at Mactaquac Generating Station is an effective way of dealing with the expansion of concrete caused by AAR. Continued improvements in diamond wire and equipment technology are increasing the efficiency of performing this work, and it is hoped that we can continue to maintain safety and smooth operations at the station in the future,” said Tim Beckman, Sr. VP of Diamond Wire Cutting Services at In-Place Machining Company.