Factories and other buildings made of masonry and brick are marvels, especially the older structures in industrial cities like New York and Chicago. Consider the material and labor involved with construction of these facilities, where every brick or block was placed by hand and every joint worked with a trowel it is astounding. This is especially true when compared with today's more efficient building methods.
What is also astounding is the realization that during the expected life span of these buildings, every one of those same mortar joints will need to be cut, cleaned and refilled with fresh mortar, often several times. This restoration process, known as tuckpointing, is part of the standard maintenance package for brick and block buildings. A large specialized industry has evolved out of the need for this kind of maintenance, with contractors dedicated to the repair of masonry and brick structures.
Why perform tuckpointing? The most common (and obvious) reason is to remove weather- and age-deteriorated mortar from the bed and head joints on buildings, monuments, chimneys and other brick or block structures. Aging and damaged mortar joints become a waterproofing problem, and eventually a structural issue, if not repaired. This means that, as a rule of thumb, tuckpointing is performed roughly every 20 years to make sure mortar deterioration does not undermine the structure. However, tuckpointing is not always limited to older structures. It can also be used for newer jobs where mortar may have been damaged or needs to be replaced because of problems with finish or color. With the trend today toward colored mortar mixes, this is even more relevant.
Tools of the Trade
It's been said that technology has a funny way of solving a big problem by leaving you with a bunch of smaller ones. Tuckpointing is no exception. Historically, tuckpointing was performed with manual tools: chisels, wire brushes and pointing trowels. Then contractors used pneumatic saws or electric, right-angle grinders and abrasive disks to grind out worn and damaged mortar. The biggest problem with these methods was the limitation of masonry blade technology. It was not uncommon for grinding disks to wear out very quickly (sometimes in minutes) or even fail while in use. This caused huge amounts of down-time, as well as worker safety concerns.
The development of tools that used a wet cutting diamond blade brought temporary relief. These tools, largely due to the use of diamond blades instead of abrasive disks, allowed for higher productivity and a more efficient means of cutting mortar. The problem with early diamond tools is that they required water as a coolant during use. This created a new set of difficulties: getting water to the site and all along the building, dealing with the wet slurry during and after the cutting process, and additional safety concerns associated with water and electricity on the same job site.
Luckily, diamond blade technology continued to evolve and new cutting devices were developed. Laser welding and better methods for manufacturing man-made diamonds produced a long-life diamond blade that could be run without a coolant: the dry diamond blade. This blade type has evolved to become the primary cutting tool for masonry and concrete cutting and is used in most tuckpointing applications today. This development allowed contractors to return to a dry cutting method using electric tools, the preferred solution for tuckpointing. However, as with other developments, this one also created its own set of problems.
The process of cutting out mortar can be very dusty and messy. Thousands of pounds of material, ranging from fine dust and sand to chips and chunks of mortar or block can be removed from a large project. At one time, the contractor was only responsible for the material that fell to the ground. The light debris and dust?...Well, that was someone else's problem. It was not uncommon for large projects to have clouds of light dust billowing from the external walls. Winds carried the dust for blocks, coating cars, pedestrians, plants and everything else in its path.
It didn't take long for this dust to be considered a nuisance, and soon jobs were shut down because of complaints and contamination. With this change, the contractor was now responsible for getting all of the dust cleaned up, a nearly impossible task. Many contractors went back to wet cutting, as the headaches from this type of clean up were far easier than the dry dust issues. Some contractors looked toward different types of secondary containment and dust collection devices similar to those that have been used in the abrasive blast industry for many years.
Most recently, regulatory groups have refined the rules of dust collection because of health and exposure issues. One of the latest recommendations is a point-of-process recovery of debris Ñ basically the use of special shrouding and dust collection systems to protect the operator as well as prevent environmental exposure of the fines produced during the cutting process.
New saws available on the market from several manufacturers address this issue. They use grinder motors to propel a dry cutting diamond blade. They have an enclosed shroud to control dust during the cutting process, which is then connected to a dust collection system via a flexible hose. During operation, dust and small particles are captured by the shroud and routed through the vacuum hose and into a dust collection system. These dust-controlling tools provide greater visibility when cutting. There are no dust clouds, and because these systems are designed to cut dry, there's no slurry produced that can block visibility. They also help remove small debris particles that can cause a blade to skip, interfering with the operator's ability to make uniform cuts. Additionally, clean-up time is dramatically reduced.
Now that we know what tools are used in the tuckpointing process, let's discuss tuckpointing basics. The first step is to cut out the mortar joint, horizontally and vertically. Select a blade width that is slightly thinner (1/8-inch) than the joint to be cut. Tuckpointing blades are typically available in widths from 1/8- to 1/2-inch. Position the saw over the mortar joint and gently ease the blade into the joint. Cutting with a diamond blade requires special attention to maintain a consistent cut in the joint line. These types of cutting tools are capable of cutting brick or block as easily as they remove mortar, so a steady hand is a must. Many contractors find it works best to position the saw at a level somewhere between waist and chest height. This provides maximum visibility, good bracing stability and reduced worker fatigue.
Usually, material is removed to a depth of between 1/2 and 3/4 of an inch. In some extreme cases, greater depths need to be reached to find sound material. Also, where brick damage or settling has severely damaged the joint, full removal and brick replacement may be necessary.
During the tuckpointing process, monitor the condition of the dust collection system and empty the dust bag when it reaches half full. A dust bag that is too full reduces or even stops the ability of the vacuum to work properly. A dust cloud is an indication that the bag is overloaded. To help avoid dust contamination when emptying the bag, wear gloves and an OSHA-approved lung protection device.
Once the bulk of the material has been removed, clean up and prepare the joints for new material. This entails chipping away any mortar remaining after cutting, brushing or rinsing out loose debris the use of pressurized air to clean out debris is no longer recommended because of dust and then performing any other special requirements a job may have.
Next, reapply material to the prepared joints. This process can be performed several ways, and much of this is based on the repair material chosen for the project. Matching the color of existing material is also important for a consistent finish.
In many cases, manufacturers recommended that the contractor first dampen the area where material is to be applied, then follow with several thin layers of mortar. Some repair materials can be applied at full depth. These materials can be applied manually or you can use "caulk guns" or other mechanical devices to inject the material into the joint. Whichever method is used, the mortar must be packed tightly into the joints. Any air gaps within the joint can trap water and cause failures under the stress of freeze-thaw cycles. Before the mortar fully sets, a final tooling will be performed to create a smooth, concave look. With a final cleaning after the mortar has cured, the job is complete.
Tuckpointing is a critical component of maintenance and repair for masonry and brick structures. Throughout the history of this industry, improvements in technology have allowed for better equipment and methods. Today's contractors have specialized tools such as dry cutting, shrouded saws that can provide improved environmental and worker protection, as well as higher productivity and efficiency.
A tuckpointing grinder uses a wheel to remove material from the mortar joint. According to Ed Pchola, product manager for grinders at Robert Bosch Tool Corp., Chicago, Ill., their tuckpointing grinders, including the newly released 1775E model, use a diamond wheel. The wheel is 1/4-inch thick, more than the usual five-inch diamond saw blade, and coated with abrasive diamonds on the segments. The wheel can be adjusted for depths from 1/2- to 3/4-inch which are common tuckpointing depths up to 1 1/4-inches for serious cleaning.
The operator is protected by a two-sided guard or shield, an important consideration as, according to Pchola, tuckpointers tend to use the grinder inverted, which would cause the normally uncovered wheel to throw debris. The shield has an acrylic "view window" that allows the operator to see the joint as he or she works the job.
Bosch has made grinders for years, of course, but the new line is specifically designed for tuckpointing, incorporating the aforementioned features with easy wheel access for exchanging elements, a multi-position head for ease of use, and protected motor windings and switches to prolong tool life. It also has a vacuum attachment that, according to Pchola, provides dust removal at a rate of 95 percent or more. That means the tool meets Underwriter's Laboratory (UL) and OSHA's requirements for a clean, safe work area.
Weighing a little over five and a half pounds with an 11,000 RPM motor, the 1775E tuckpointing grinder should make completing tuckpointing less stressful and more worker-friendly, whether the job site is near the top of a high-rise or the bottom of a residential chimney.
Bill Glynn is National Product Manager for Sawtec, based in Houston, Texas. He has been involved with development and testing of dust reduction tools for many facets of concrete and masonry restoration.
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