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Concrete Sawing and Drilling...The CSDA Professional Advantage
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Concrete Sawing and Drilling...
The CSDA Professional Advantage

by Patrick O'Brien
CSDA Executive Director


Introduction
The concrete sawing and drilling industry began in North America in the late 1940's when a flat saw was utilized experimentally to saw highway joints. Since those early beginnings many changes have occurred in diamond tools that saw and drill concrete. The early homemade machines have been replaced by modern, efficient machines capable of a far wider range of applications than the original machines. Today architects, engineers, general contractors and government officials can take advantage of these advances in technology by employing a specialized sawing and drilling contractor who utilize these diamond cutting techniques in the construction and renovation industry.
Contractor Advantage
The specialty contractors who perform the concrete sawing and drilling services are experts in their field. The Concrete Sawing & Drilling Association (CSDA) is a nonprofit trade association of contractors, manufacturers and affiliated members from the concrete construction and renovation industry. The CSDA mission is to promote the selection of professional sawing and drilling contractors and the use of their methods. Founded in 1972, CSDA has over 425 international member companies.

CSDA contractors are professionals who can recommend the best techniques and equipment for the most cost-effective cutting, and are better prepared to bring projects in on time and within budget. In addition, they have the training and experience to select the best sawing and drilling procedures to employ at any stage of the project. Over 50 companies have achieved Certified Operator status by successfully completing the only industry certification program of its kind. CSDA operators know which types and sizes of saw blades, drill bits and wires are best for the application, as well as a full understanding of working clearance, disposal, or other construction site issues.
Concrete Cutting Advantage
Knowledgeable contractors recommend and use diamond cutting systems because they can provide significant cost advantages over conventional concrete removal methods. These advantages vary depending on the project but include reduced downtime, precision cutting, maintenance of structural integrity, reduced noise, dust and debris, limited-access cutting, and the ability to cut heavily-reinforced concrete. These advantages have revolutionized the concrete cutting industry. The chart below details the specific advantages over conventional concrete removal systems:
DIAMOND
CUTTING SYSTEMS
CONVENTIONAL
REMOVAL SYSTEMS
TIME
-Fast
-Fewer Operators
-Pre-outage work possible
-Cuts rebar and other metals
-Slow, methodical
-Labor-intensive
-Pre-outage work not possible
-Metal cutting required
DIMENSIONAL TOLERANCE
-Precise Cuts
-Limited patchwork required
-Uncontrolled openings
-Extensive patchwork required
STRUCTURAL INTEGRITY
-Vibration free
-Ability to remove large amounts of concrete while maintaining sturctural integrity
-High impact vibration causes microfractures of concrete
-Potential damage to remaining structures of nearby equipment
NOISE, DUST, DEBRIS
-Non-disruptive to surrounding operations
-Relatively quiet
-Pieces cut to size
-Dust free
-Large bulk removal capability
-Disruptive
-Loud
-Creates rubble
-Extremely dusty
-Time-consuming clean-up
LIMITED ACCESS
-Remote operations possible
-Cuts in close space
-Underwater operations possible
-Easily cuts around existing pipes, existing electrical fixtures and equipment
-Inflexible equipment
-Restricted movement
-Underwater operations difficult or impossible
-Difficult to work around piping and equipment

Concrete Cutting Techniques
Diamond cutting techniques utilized by cutting contractors vary depending upon the application and job site requirements. The main concrete cutting tools that are utilized include the wall (or track) saw, the flat (or slab) saw, the core drill, and the wire saw. Each of these cutting tools is described in this article and a typical application of the tool will be given.
Wall Sawing
Wall sawing employs a circular blade on a track-mounted machine. The track is attached to vertical walls or steep inclines, or floors, that will not permit the use of flat saws. Wall or track sawing is typically specified to cut precise dimensional door, vent and window openings. Straight as well as bevel cuts are possible with the wall saw. The wall saw is also an excellent choice for creating precise openings in any concrete structure.

The diamond wall saw blade consists of a circular steel core with diamond segments attached to the periphery. The blade is mounted on the spindle of the wall saw. The spindle runs along the wall saw track that is typically bolted to the cutting surface. The power source for a wall saw system is either hydraulic, air or electric. Wall saw blades can range from 18 to 72 inches (457 mm to 1.8 m) in diameter and can cut up to 33 inches (838 mm) in depth.

The use of a wall saw allowed a general contractor to safely remove a silo in the middle of existing buildings to perform a renovation of a fire brick manufacturing plant in Manistee, Michigan. A CSDA contractor was hired to remove the silo in the middle of the winter with temperatures below freezing. The 57 foot (17 m) tall reinforced concrete silo was cut with the wall saw and removed in three 19 foot (5.8 m) sections. In total, 1,025 feet (312 m) of 9 inch (229 mm) thick and 341 feet (104 m) of 12 inch (305 mm) thick reinforced concrete, weighing over 350 tons, was removed in only six weeks. The general contractor could not have performed this project without the services of a professional CSDA contractor and the use of the wall saw.
Flat Sawing
Flat sawing is the most commonly used diamond cutting method. It is typically used to cut horizontal flat surfaces such as floors, bridge decks, and pavement. Also called slab saws, flat saws feature a diamond blade that is mounted on a walk-behind machine requiring only one operator. Flat saws are typically used to provide expansion joints, remove damaged pavement sections, clean and repair random cracks for repair, and remove concrete sections for demolition purposes.

As with the diamond wall saw blade, a flat saw blade consists of a circular steel core with diamond segments attached to the periphery. The blade is mounted vertically on the spindle of the flat saw. The flat saw is pushed or propelled along a flat surface while the diamond blade makes the vertical cut to the required depth. Flat saws are typically powered by gasoline or diesel engines, electric or hydraulic sources. Flat saw blades can range from 12 - 54 inches (305 mm - 1.4 m) in diameter and can cut up to 24 inches (610 mm) in depth.

While flat sawing has many highway and airport applications, a typical building application is the removal of floor structures. A CSDA contractor removed three levels of a Syracuse, New York parking building. The parking deck had to be removed after a section collapsed and made the building unsafe. The concrete structure was primarily made of 10-1/2 inch (267 mm) thick cast-in-place concrete with 5/8 inch (16 mm) rebar on 12 inch (305 mm) centers. Over 3,048 feet (929 m) of 15 inch (381 mm) slab, 3,048 feet (929 m) of 8 inch (203 mm) slab, 24,476 feet 7460 m) of 10-1/2 inch (267 mm) slab, 3,058 feet (932 m) of 15 inch (381 mm) slab, and 933 feet (284 m)of 18 - 24 inch (457 - 610 mm) slab was cut with flat saws and removed by cranes. Slab sawing, as well as wall sawing, was the best demolition choice due to its speed, control of the process, low noise in a downtown setting and safety in a confined area.
Core Drilling
Core drilling techniques are used when precise, circular cuts are needed. Holes of almost any diameter are easily drilled to make openings for plumbing, electrical and HVAC installations. Core drilling is also commonly used to create holes for routing cables or placing anchoring bolts, installing load carrying devices or dowel bars, or for concrete sample analysis.

A core drill bit consists of a steel tube with diamond segments brazed or laser welded on the drilling end. The core bits are mounted on the rotating shaft of various types of drilling machines. Core drills can be operated in any orientation, vertical or horizontal. Core drill machines can be powered by electric, hydraulic or air power sources. Core drill bits can range in diameter from 1/2 - 60 inches (13 - 1524 mm) and drilling depths are virtually unlimited with the barrel extensions.

Core drilling played a major part in a hospital renovation in Halifax, Florida. A CSDA contractor was hired to remove a 20-foot by 20-foot by 4-foot (6.1 x 6.1 x 1.2 m) tower crane footing that had been left behind when the hospital was originally built. Three electric drills were used to line drill 355 6-inch (152 mm) diameter holes to a depth of 4-foot 6-inches (1.4 m). Line drilling is a process whereby the holes are drilled one next to another in a line. This process was used to partition the footer into 4-foot by 4-foot by 4-foot (61. x 61. x 61. m), 6-inch (152 mm) sections weighing approximately 11,000 lb. each. A total of 355 holes were drilled in 10 days. This project utilizing core drilling allowed the renovation to be completed within budget; allowed undisturbed use of the existing facilities; and demonstrated the advantages of today's diamond tool cutting techniques as used by a professional CSDA cutting contractor.
Wire Sawing
Wire sawing is a technique that originated in quarries to extract stone. It has proven to be an ideal choice for removal of thick sections of concrete. A multi-strand cable with diamond segments is threaded through a series of pulleys and is continuously pulled through the concrete. Since virtually no concrete structure or cross-section is too large to cut, wire saws are used where other cutting methods are impractical. The only restriction is the lifting and removal specifications of the job. Wire sawing is ideal for removing large sections of heavily reinforced concrete, such as piers, towers and bridge sections, and cutting concrete in areas where work space is restricted.

A wire saw consists of a multi-strand cable with diamond segments that are threaded through a series of pulleys attached to a drive wheel that is powered by a hydraulic power unit. The combination of the spinning wire and constant pulling force cuts a path through the concrete and steel reinforcement. A typical wire diameter is 3/8 inch (10 mm). Wire saws can cut in any orientation, vertical or horizontal. Because the length of wire can be made to virtually any length, the cutting depth is unlimited.

A nuclear power plant renovation in South Haven, Michigan was performed with the use of a wire saw. Four large blocks of concrete with a steel liner were cut in order to change steam generators. The blocks of concrete were 3-1/2 foot (1.1 m) thick with 2 inch (51 mm) diameter rebar and lined with 1/4 inch (6 mm) thick steel plate. The largest block measured 28 foot by 27 foot (8.5 x 8.2 m). The sawing was accomplished in nine days using two four-man crews. The capability of the wire saw, in combination with the expertise of the professional CSDA cutting contractor, allowed this project to be completed in time and under budget.
Conclusion

Concrete sawing and drilling is truly the professional advantage in the concrete building and renovation industry. The cutting tools have many advantages and can also provide increased productivity over other renovation methods. And with the expertise of a professional CSDA contractor, the true advantages available including reduced downtime, precision cutting, maintenance of structural integrity, reduced noise, dust and debris, limited-access cutting, and the ability to cut heavily-reinforced concrete can be realized. Contact CSDA at 727-577-5004 or visit the CSDA web site at www.csda.org to find the name of the nearest concrete cutting professional who can help bring your project in on time and within budget.


Information for this paper was provided by the contractor and manufacturer members of CSDA.

The Concrete Sawing & Drilling Association is a nonprofit trade association of contractors, manufacturers and affiliated members from the concrete construction and renovation industry. The CSDA mission is to promote the selection of professional sawing and drilling contractors and their methods. Concrete cutting with diamond tools offers industry many benefits including lower total project costs, precision cutting, maintenance of structural integrity, reduced downtime, reduced noise, dust and debris, limited access cutting, and the ability to cut heavily-reinforced concrete. Founded in 1972, CSDA has over 475 international member companies.

               

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