Concrete Demolition Techniques

Pneumatic & Hydraulic Breaking

• Pneumatic or hydraulic breakers offer a popular approach for shattering pavement and foundation concrete. The pneumatic varieties are powered by compressed air, while the hydraulic breakers rely on compressed fluid from a pump. Hand-held pneumatic breakers are often called jackhammers. Machine-mounted breakers are also available and can exert substantial force at rates as high as 300 to 800 blows per minute. While they're versatile and very effective, breakers are incredibly noisy and can create a lot of dust.

Pressure Bursting

• Pressure bursting is a somewhat slower method that breaks the concrete into smaller sections rather than shattering it altogether. In mechanical pressure bursting, a hole is drilled into the concrete and a machine exerts increasing hydraulic pressure to fracture the concrete. In chemical bursting, by contrast, chemicals are introduced into boreholes, where they react and expand to fracture the concrete around them. Controlling the crack direction with mechanical bursting can be difficult, however, and chemical bursting is more expensive.

Dismantling

• Concrete can also be cut into smaller blocks and removed by crane. Contractors may cut the concrete with saws, water-jetters or thermic lances. The water jetter uses a high-pressure blast of water mixed with an abrasive or scratchy material, while the thermic lance burns iron to create temperatures so high it can eat into the concrete. Both methods minimize dust, although the thermic lance approach may involve fire hazards and can cause surrounding concrete to deteriorate somewhat.

Wrecking Ball and Explosives

• The wrecking ball is a time-honored approach. A massive ball swinging from the end of a crane batters the structure until it crumples beneath the blows. This technique requires some skill and experience, however, and may be unsuitable if power lines are located nearby. Explosives may be useful for dealing with large quantities of concrete, although they make a lot of noise and can pose severe safety hazards if used improperly.