By Todd Ferguson
Grout pumps and material delivery systems are utilized on jobsites to fill concrete masonry units (CMUs), providing structural stability to masonry walls according to project specifications. These pumps and systems include material valves designed to allow the flow of grout from the equipment to the block. The most common material valve designs in the industry are the swing-tube, ball-check, rotor/stator and auger material delivery systems, each having their own advantages.
Masonry grout pumps with swing-tube (S-tube) material valve designs offer the most compatible system for pumping fine or coarse grouts. The S-tube valve is a proven technology used on virtually every concrete pump truck (boom truck). In the masonry industry, contractors can take advantage of the same technology on a smaller scale, more suitable to their job size.
The S-tube is an S-shaped steel pipe that allows continuous flow of material from two material cylinders in the pump. These two material cylinders contain a piston to push material through the cylinders. As one cylinder draws in material from the hopper, the other is loading material into the S-tube. The S-tube valve “swings” several times per minute, alternating between each material cylinder. It has a full-flow internal fluidway. This allows the S-tube to work with material mix designs containing coarse aggregates. For example, masonry contractors wanting to use a 3,000 psi (207 bar) mix design containing aggregates up to 1501/2-inch (12.5-mm) diameter would select a masonry grout pump with S-tube valve design to ensure those larger aggregates pass through the
pump. Maximum aggregate sizes stated by the manufacturer may be as high as 3/4 inch (19 mm), although pumping these large aggregates may require a higher compressive strength mix design and large-diameter material delivery hoses.
S-tube pumps are especially suited to pumping grout from ready-mix trucks because of their ability to keep pace with the yardage coming out of the truck. They can also be used with mortar mixers, although it is important to consider that a grout pump will almost always pump faster than the mixer can produce materials.
Bottom line: the S-tube is the choice for high-production, continuous pumping of fine or coarse grouting materials — especially when sourced from ready-mix providers.
Pumps with ball-valve or ball-check designs are also used for masonry grouting. These designs are used on mechanically driven and hydraulic grout pumps. The ball-valve design uses two balls made of either steel or hard plastic to create suction between the hopper and material cylinder in the pump. One ball is located below the material hopper, and the other at the discharge of the pump. The material cylinder contains a piston, which forces material from the hopper valve toward the discharge. This cylinder is constantly cycling forward and backward when the pump is switched on. As the cylinder cycles back during the retract stroke, the discharge ball is seated, sealing off material from flowing out of the discharge. At the same time, the hopper ball is “unseated,” allowing material to flow from the hopper into the cylinder. The opposite is true in the forward stroke: the hopper ball is seated, sealing off material from entering the cylinder from the hopper, and the discharge ball is unseated, allowing material to pass out the discharge into the grout hose.
Ball-check pumps may include a single cylinder or may combine a main cylinder with a compensating cylinder to reduce the surge effect caused by the retracting and extending of the piston. Contractors wanting to use maximum aggregate sizes published by ball-check pump manufacturers may have to limit the overall aggregate percentage, while maximizing cement and compressive strength of the material, in order to make a pumpable mix for a ball-check system. Ball-check pumps are generally very good at handling a high-slump material, cement slurry, mortar or high-strength grout containing 3/8-inch (9.5-mm) aggregates.
Bottom line: the ball-check design is suited to medium to high production and works best with fine aggregate mix designs.
Another design used for specific masonry projects, the rotor/stator pump, offers a solution for lower-production jobs. This design is also called a “worm pump” or “moyno,” based on the original U.S. manufacturer’s trade name. It includes a rotor made of alloy or stainless steel shaped like a drill bit. The rotor is placed inside a molded stator made of polyurethane, designed to encapsulate the rotor while leaving enough space for rotation. The rotor/stator design provides a continuous, smooth flow of material without pulsation. It can receive material from a hopper mounted over it. Normally, the hopper has a large cutout in the bottom called an “open throat,” which allows material to freely enter the rotor. Because of the small space between the rotor and stator and the
susceptibility to wear, these designs have very strict limitations on aggregates. Most of these pumps are not able to handle over 1/8-inch (3-mm) particle sizes. Rotor/stator production rates are well below the average outputs of S-tube and ball-check pumps. Still, these pumps have their place for lower-production jobs, such as tuck pointing, mortar spray and other void-fill requiring a precise, smooth flow of material.
Bottom line: rotor/stator designs can provide a continuous flow of grout without aggregates.
Material delivery systems offer a simple yet efficient valve design. They consist of an auger that continuously feeds grout from a large-capacity hopper to the dispensing hose. Delivery systems are elevated above the masonry wall and use the force of gravity to move grout through the dispensing hose into the CMUs. These systems essentially take the place of manually pouring buckets of grout into the walls by offering a machine to automate the pouring of grout with an auger. The standard unit is powered by auxiliary hydraulics from a forklift, which is also used to lift it into position. The forklift operator controls the auger. It can be configured into an extended auger tube for higher vertical reach. Extending the auger tube reduces the maximum aggregate to 1/2 inch (12.5 mm), whereas the standard auger configuration is compatible with 3/4-inch (19-mm) aggregate grout mixes. The auger can be reversed to
stop grout flow for an extended period of time and is easily removed for cleanup. Because they have to be elevated for use, material delivery systems are best suited for smaller batches of material from a mortar mixer versus larger loads from ready-mix trucks.
Bottom line: the auger system is an option for masonry grouting with a forklift when overhead space is accessible and the size of the project is suited to mixing onsite.
Material valve designs are available to suit the needs of every masonry contractor. Whether their priority is material specification, production rate, aggregate size, material source, flow characteristics or design simplicity, contractors can choose a material valve to match their grouting requirements. Contractors should also rely on manufacturers of grouting pumps and delivery systems to review grout specifications and recommend the most suitable grouting solution for the project.
Todd Ferguson has more than a decade of experience in specifications for grouting equipment, accessories, materials and applications. He is international sales representative for Airplaco Equipment, a manufacturer of grout and shotcrete pumps. For more information, call (513) 321-2950 or visit www.airplaco.com.
Product to Watch
Toro’s UltraMix Mortar Mixer Line
|The new UltraMix lineup from Toro delivers the ultimate in mixing performance, thanks to an exclusive symmetrical drum and patented paddle configuration. The unique design boasts more paddle and drum contact with the mortar, and the Toro-exclusive paddle design moves mix horizontally, as well as in the circular motion. This ultimately maximizes productivity for busy masonry contractors by providing an ideal mixture while reducing mixing time.
In addition to producing an outstanding mortar blend, the new UltraMix line features rugged and reliable components that are designed with durability in mind. The reinforced paddle rubber features two layers of woven fabric for added strength, minimizing tearing and increasing overall paddle life. Additionally, the drum boasts high-strength steel, which effectively resists pounding during mixing or transport. The UltraMix line is also equipped with solid steel dump handles, and a high-strength telescoping axle. This feature allows the wheels to adjust from a towing width to under 36 inches, allowing the unit to easily pass through a door opening.
For more information, visit www.toro.com.