Cutting concrete and other masonry materials generates a large amount of dust that may contain high levels of crystalline silica and create a hazard for everyone in the vicinity. Increasingly, nano-enabled masonry products are being used in construction that can also expose workers to inhaling engineered nanomaterials when the products are being cut.Concrete that contains nano-size titanium dioxide is an example. Wet suppression is a control option for dust generated while cutting masonry materials with walk-behind masonry saws. These controls use a pump or line pressure to deliver water to the saw blade where it combines with particles and reduces airborne dust levels.  Without dust controls, user and bystander exposures are almost certain to exceed OSHA limits for total dust (15mg/m³) and exceeded limits for crystalline silica.

If properly designed and used, exposures can be reduced 50 to 95%. If use is brief and intermittent, this may reduce exposures enough that a respiratory protection program isn’t required. Continuous use may exceed the OSHA Permissible Exposure Limit, even with the use of wet dust suppression, however.

EDCO, Inc. 14-inch down-cut walk-behind concrete/asphalt saws with water connection

• Used for short-run slab cutting, contraction joints, patch repairs in asphalt, traffic loop installation and trenching
• Cost: $2,054 (optional water tank is an additional $221)
• Blade diameter: 14 inches
• Maximum cutting depth: 4 ¾ inches
• Sound pressure level: greater than 85 dBA and likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

• Used for short-run slab cutting, contraction joints, patch repairs in asphalt, traffic loop installation and trenching
• Blade diameter: 18 inches
• Maximum cutting depth: 6 ¾ inches
• Sound pressure level: greater than 85 dBA and likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

• Used for Highway, road and bridge deck repair, utility installation and traffic loop installation
• Maximum blade diameter: 20 inches (16 inches for SS-20-13H)
• Maximum cutting depth: 6 ¾ inches
• Sound pressure level: Greater than 92 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)

• Used for Highway, road and bridge deck repair, utility installation airport construction and traffic loop installation
• Maximum blade diameter: 26 inches (blade guards that will accommodate 14 to 30 inch blades are available)
• Maximum cutting depth: 10-1/2 inches
• Sound pressure level: Greater than 92 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)

• Used for Highway, road and bridge deck repair, utility installation airport construction and traffic loop installation
• Maximum blade diameter: 36 inches (blade guards for smaller blades are available)
• Maximum cutting depth: 15 inches
• Sound pressure level: Greater than 92 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)

• Used for small to medium concrete cutting jobs
• Blade diameter: 14 inches (12-inch blade is optional)
• Maximum cutting depth: 5-1/2 inches (with a 14-inch blade)
• Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

• Used for small to medium concrete cutting jobs
• Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

• Used for cutting concrete
• Power: 35 horsepower gasoline
• Weight: 1,150 pounds
• Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

• Used for cutting concrete
• Power: 30 horsepower diesel
• Weight: 1,190 pounds
• Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

• Used for cutting concrete
• Power: 48 horsepower gasoline
• Weight: 1,120 pounds
• Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

• Used for cutting concrete
• Power: 44 horsepower diesel
• Weight: 1,080 pounds
• Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

• Used for concrete cutting
• Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

• Used for cutting concrete
• Water supply: ¾-inch hose connection (water tank is available)
• Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

• Used for cutting concrete
• Water supply: ¾-inch hose connection (water tank and pump are available)
• Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

• Used for joint sawing, floor sawing, trenching, road repair and other cutting applications
• Cost: $3,360
• Blade diameter: Up to 20 inches
• Blade speed: 2,900 RPM
• Maximum cutting depth: 7 inches
• Weight: 107 pounds
• Water supply: ¾-inch hose connection
• Alternative dust control: port for use with vacuum
• Sound pressure level: Not available but likely to exceed 90 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average)

 

• Used to cut concrete or asphalt floors, driveways, highways, streets and runways
• Fuel: diesel
• Engine horsepower: 84
• Water supply: ¾-inch hose connection (water pump kit is available)
• Sound pressure level: 95 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)

(Photo courtesy of Husqvarna AB Construction Division)
 

• Used to cut concrete or asphalt floors, driveways, highways, streets and runways
• Fuel: diesel
• Horsepower: 66
• Water supply: ¾-inch hose connection (water pump kit is available)
• Sound pressure level: 95 dBA (OSHA’s Permissible Exposure Limit for an 8-hour time-weighted average is 90 dBA)

(Photo courtesy of Husqvarna AB Construction Division)

Hilti DSH-FSC Gas Saw Floor Cart and DSH 700/900 Hand-held gas saw

• Used to cut concrete or asphalt floors, driveways, highways, streets and runways
• Fuel: diesel
• DSH-FSC Gas Saw Floor Cart: constructed from heavy duty steel with a gravity feed water container that allows the cart to be portable while still providing wet dust suppression; can be combined with the DSC 700/900 hand-held gas saws

STIHL TS 410/420/700/800 and Cutquik Cart Kits with water tank

• Used to cut concrete or asphalt floors, driveways, highways, streets and runways
• Fuel: diesel
• STIHL Cutquik Cart Kit: includes a water container that allows the cart to provide wet dust suppression; can be combined with the STIHL TS 410/420/700/800 hand-held gas saws; mounting kits must be purchased separately.

Wacker Neuson BFS 614, BFS 914, and BFS 1318 with water connection

• Used for cuts in asphalt or concrete
• Fuel: gasoline

Wet dust suppression systems can have either positive or negative effects on productivity, but definitely improve the quality of the work by suppressing large amounts of airborne dust, which allows a cleaner, more efficient means of masonry cutting.

Dust suppression also reduces site cleanup times. Dust suppression avoids exposing other workers, members of the public, adjacent property, cars and building occupants, which can increase liability and time-consuming disputes. Improved worker comfort is a result of reduced airborne dust which may in turn result in less fatigue for the worker and greater productivity. In some cases, particularly where saw use is intermittent, wet dust suppression may be adequate to reduce the need to wear a respirator, and the need for an employer respiratory protection program.

Some additional issues should be considered. Time may be required to allow masonry materials to dry after cutting and before use, which will depend on the material, the amount of water used and the application. In addition to electrical power requirements, the saw needs to be located near a source of water.

The use of water controls may result in wet and slippery ground and walking surfaces. During cold weather this may lead to the formation of ice and an increased risk of slips, trips and falls. Cutting debris that is not removed from the work area while wet may become airborne once dried, posing an inhalation hazard to anyone in the area. Maintaining a work area free of debris and excess water reduces the risk of these hazards.

The use of water as a dust control increases the risk of shock when electricity is used in the same area. Electrical cords and extensions must be rated for the tool's power requirements, be regularly inspected, replaced when damaged, and used in combination with ground fault interrupt circuits.

The use of gasoline-powered equipment poses the risk of carbon monoxide exposure, particularly in areas where airflow is reduced. Steps to control exposure are important because the gas is invisible, odorless and tasteless. Poisoning by carbon monoxide can occur quickly indoors, but working outdoors does not ensure operators won’t be overcome. Small, inexpensive personal monitors should be worn by the operator to warn of unacceptable exposures.

Walk-behind masonry saws frequently generate sound levels that are greater than 90 decibels, the OSHA Permissible Exposure Limit (PEL), and hazardous. Hearing protection should be worn when using masonry saws unless an industrial hygienist has conducted noise monitoring and indicated that hearing protection is not required.

As is the case with any construction equipment, users should follow manufacturer safety recommendations and comply with any applicable local, state or federal regulations.
 

Bruce Lippy, PhD, CIH - CPWR - The Center for Construction Research and Training
Michael R. Cooper - Aria Environmental, Inc.
Bill Kojola, MS