How to select a conventional mortar mixer Consider capacity, mixing speed and uniformity, durability, ease of maintenance, and safety features By Carolyn Schierhorn mortar mixer that runs efficiently, never breaks down, lasts forever, and glides smoothly over any terrain when towed: Consider how this ideal machine would propel productivity and profits. Though the perfect mortar mixer remains a contractor’s pipe dream, many mortar mixers today do offer features that translate into benefits for the contractor. But choosing the right mortar mixer can be a challenge. There are more than 20 mortar mixer manufacturers, some offering over a dozen models, each model with an assortment of options. Before wading into this sea of choices, masonry contractors should first look inward and analyze their firm’s specific needs. A Capacity Mortar mixers range in price from about $1,500 for a model with a 4-cubic-foot, single-bag capacity to $6,000 for a model with a 16-cubic-foot, 4 1⁄2- to 51⁄2-bag capacity. Prices increase dramatically at the upper end of the capacity spectrum because of the heavy-duty materials and additional power required. Opting for a 16-cubic-foot instead of a 12-cubic-foot model, for example, could easily add more than $2,000 to the price. Determining what size mortar mixer to buy, therefore, is a most critical decision—one that has been complicated by the persistent construction slump. Many masonry contractors have taken on smaller-than-usual projects, including repair and rehabilitation jobs, during the downturn. If this represents a long-term shift in business for the individual firm, a smaller 6- or 8-cubic-foot mixer may be a better investment. If buying a paddle mixer, examine the However, if the shift is paddle configuration and the shape of seen as temporary, it may the drum. pay to invest in a larger model. Consider renting a higher-capacity model. mortar mixer when unsure of fuAccording to one mixer manuture needs. Remember that the avfacturer, masonry contractors tend erage life of a properly maintained to overload their mortar mixers, mortar mixer is five to 10 years. which prevents aeration of the But even on major projects, to remortar and movement of the mix duce material handling costs, from one end of the drum to the some contractors today will use other. This can cause inconsistency two smaller mixers where they of color and structural properties. previously would have used one When determining the optimum mixer size for your operations, realize that the drum size does not equal the mixing capacity. The drum should be filled only to a level three inches above the centerline of the paddle shaft. Power Gasoline-powered mortar mixers usually are priced higher than electric-powered models of comparable capacity, but use, not cost, should dictate the power source. Gasoline-powered mixers generally are more convenient because they don’t have to be plugged in. In remote areas, lack of electric power lines may necessitate the use of gasoline-powered models. But only electric mortar mixers can be used indoors, a growing consideration for masonry contractors accepting more interior remodeling jobs. Just about every mortar mixer comes with a variety of engine options—usually one electric engine, plus two or more powered by gasoline. Engine choice tends to be subjective, based on personal experience and preference, with many masonry contractors swearing by particular brands. Engines run constantly and take a lot of abuse; consequently, even a masonry contractor who changes an engine’s oil every three to five days is lucky to get five years of life out of that well maintained engine. Typically, two or three engines are needed during the lifetime of a mortar mixer. Three types of power trains are available on mixers: open gear and belt drive, enclosed gearbox drive, or hydraulic drive. Although they cost more than the others, hydraulic-drive models are less expensive to maintain because they have no gears or bolts to shear and no belts or clutches to wear out. Performance Quality performance should be near the top of any masonry contractor’s list of mixer selection criteria. But all too often, performance is taken for granted. If buying a paddle mixer, examine the paddle configuration and the shape of the drum. Short, deep drums are more efficient than long, shallow drums because the blades don’t have to move the material as far. Expect models with long drums to have as many as eight paddles for uniform mixing action. Choose a model that has steel paddle arms with rubber blades, which keep the drum cleaner and provide a more uniform mix. Also, look at spiral mixers for added speed and more efficient mixing action. A spiral mixing blade works like a spiral conveyor, rapidly moving material across the drum. But spiral mixers cost $200 to $300 more than comparable paddle mixers and are more expensive to repair. If one paddle mixer blade is damaged, the individual blade can be replaced; but if a spiral blade is damaged, the entire mixing blade must be replaced. Maintenance When shopping for a mortar mixer, Guy Michel of Alsip, ILbased Michel Masonry Co. values ease of maintenance above all other considerations. The first component of a mortar mixer to give out, he notes, is usually the packing, which helps form the seal where the paddle shaft is attached to the drum. Mortar seeping through the packing will eventually cause the blade to freeze. With certain mixer models, it is very difficult to replace the packing, and some models require daily packing adjustment. Michel prefers to buy mixers with packing that is easy to replace and requires little or no adjustment. Examine the drum: The hub should be bolted, not welded, which makes shaft-bearing replacement easier and much less expensive. According to one manufacturer, a polyethylene drum can save cleanup time because mortar can be quickly and easily freed from this surface with minimum effort and without dents or rust. Always ask the dealer how quickly various parts can be replaced. Some manufacturers tout readily available, off-the shelf industrial components that allow replacement with minimal downtime. Durability Though the blades and shaft bearing need considerable maintenance, the drum should last throughout the life of the mixer. Make sure that a metal drum is constructed of heavy-duty steel since thick drums withstand more abuse and wear than thin ones. In addition, the drum sections should be precision-cut to size. Lap welds are stronger than butt welds. One clue to an engine’s durability is the cowl. If this protective cover is spacious and well-ventilated, more air will pass through the engine. A cool engine lasts longer. Mobility Even heavy-duty steel won’t withstand the bouncing, caroming, and capsizing that may occur in a troublesome tow. A mortar mixer should have a low tow pole to minimize the possibility of jackknifing. For clearance over rough ground and curbs, the tow pole should have a downward pitch. Check to see that the tow pole has a second safety bolt to prevent it from coming out of the frame. Also, insist on a heavy-duty, steelreinforced foot, designed to reduce stress on the leg and tow bar and help prevent bending, twisting, and excessive vibration. And high-speed tires are a must if you intend to tow the unit faster than 45 miles per hour. In these tough times, masonry contractors are traveling farther and more frequently, as projects tend to be smaller and not necessarily close to home. As a result, ease of towing is especially important today. Safety Whether out of genuine concern for worker safety, fear of OSHA fines, or the desire to reduce workers’ compensation premiums, masonry contractors are paying more and more attention to safety features. Mortar mixers should have safety guards that combine operator protection with easy access for cleaning. In addition, a mixer should have a clutch handle that disengages the paddles while the machine is still running. A well-ventilated cowl or engine cover affects safety, as well as performance and durability. If too little air is reaching the engine, masons may be tempted to open the cover, thus exposing themselves to safety hazards. The cowl keeps dust and foreign objects from entering the engine and being spewed out at the workers. Efficiency Additional features can help boost worker productivity. Notice where the drum latch is located. According to one manufacture r’ s literature, the latch should be placed so that if the operator uses his hands in dumping, he can release the drum latch with his knee. Another time-saving feature is a guard lifter, which automatically moves the guard out of the way as the mix is being discharged. Consider buying a mixer with an attached measuring sandbox to ensure that the same amount of sand is used in every mix. This counteracts any tendency to use too little sand. Properly measured sand should make the mortar go farther, saving time and money. Versatility Because masonry contractors today have widely varying job requirements, mixer versatility can be a crucial issue. Some mixers, for example, have adjustable axles that contract to fit through narrow doorways. Also available are versatile two-in-one paddle-blade designs, which sandwich long-lasting rubber blades between strong steel blades. With highly abrasive mixes, the rubber blades can be removed and the steel blades extended. Assigning priorities to the benefits that various features provide will help you answer that critical question: Which mortar mixer or combination of mixers will best meet both my current and projected needs? PUBLICATION #M930119 Copyright © 1993, The Aberdeen Group All rights reserved