Mortar machines are among the most versatile machines on a construction site, springing into action after building structures are completed. They perform the onsite operations of mixing, conveying and placing mortar for finishing applications on walls and floors.
Mortar and concrete share some similar essential ingredients, cement, sand and water, but that’s where the similarity ends. Mortar has finer grains compared to the coarse aggregate in concrete. While concrete provides the stability and strength of building and structures, mortar provides protection and visual finish. Mostly applications of mortar machines start where those of the concrete machines end, after the structural strength of a building is achieved. In layman’s terms, when mortar machines are in use, a building is nearing completion.
Mortar machines provide the portability and installation convenience to be operated from anywhere on a construction site. As they can be transported on hoists or lifted using cranes within the construction sites, it is common to see mortar machines being operated from the top most floors of high-rise buildings and mortar being conveyed to lower floors.
The major applications of these machines include plastering where mortar is mixed, pumped and sprayed for finishing; these include floor screeding where screed material is mixed, conveyed and applied as a layer between the concrete surface and finishing surface (tiles or wooden flooring); shotcreting where shotcrete material is sprayed with high pressure on a surface, particularly for slope stabilisation, tunnels, pools, and concrete repairs where mortar is sprayed onto a damaged surface. Other applications include pumping and spraying fire protection mortar on steel structures to extend the fire resistance of steel, processing and spraying glass fibre reinforced concrete, injection of mortar material to fill the voids, and delivering mortar to depths for geothermal drilling.
All these machines use different pumping technologies such as compressed air conveyors, mixer pumps, double and single piston pumps, and worm pumps. Compressed air conveyors operate according to the plug conveyance principle and are suited to conventional screed applications. Materials (aggregate, binder, water) are added to the mixing vessel, mixed and then conveyed by air in a semi dry consistency to the required floor area. Some of the compressed air enters the pressure reservoir as header air and is mixed with the material to be conveyed. The remainder enters the pressure line, separates the material into plugs and pushes them along the hose to be delivered via the discharge chamber.
Mixer pumps are equipped with a rotor and stator system. The hopper can be filled with bagged goods or premixed dry mortar via an air injection hood. The material enters the mixing pipe assisted by the agitator, and the water quantity can be adjusted accurately and added directly to the dry mortar in the mixing zone before conveyed through the rotor stator system.
Double piston pumps operate with a high degree of reliability. The low set agitator conveys concrete to the cylinder openings, and two changeover cylinders move the S-transfer tube back and forth between the pressure and suction openings. Hard chrome plated delivery cylinders, spectacle wear plates made from hardened steel and the design of the S-transfer tube system ensure a long service life.
Mechanical single piston pumps are suited to extreme conditions and are appropriate for site mix plastering applications where plaster sand, cement, water are mixed at site, conveyed and sprayed, compared to manual application. The material is conveyed from the mixer through the hopper to the intake opening, where the delivery piston draws it through the valve housing. Automatically controlled ball valves then operate to open the channel to the pressure outlet of the pump. The delivery pistons are driven by a cam disc and operate with a counter stroke, where by one piston offers a balancing function.
Worm pumps have a robust design suited to convey high viscosity premix mortar materials. The material flows steadily out of the feed hopper and into the screw conveyor assisted by the mixer shaft. The conveyor consists of a rotating steel shaft (rotor) and a flexible rubber housing (stator), and the delivery rate and pressures depend on the geometry of these parts.
Binoj B.S, regional sales and application manager, Putzmeister Mortar technology, points out that each mortar machine is designed to work with a certain material composition, which varies with different applications. Therefore, it is crucial to select the appropriate machines for different applications and material compositions.
Binoj B.S, regional sales and application manager, Putzmeister Mortar technology
“We offer our expertise in choosing the right machines and accessories for each application. For instance, contractors may need to use new materials for special applications and they may not be aware about the most compatible machines for the applications. We provide assistance in selecting the right machine and accessories by analysing the mortar composition, type of aggregate, mixing time, pumping distance and other parameters. We conduct on site demos also with our machines for new material and to identify and support various application requirements at the sites,” says Binoj.
Putzmeister’s mortar machine offerings for the Middle East markets include compressed-air screed conveyors for conventional screed, self-levelling screed pumps, plastering machines, and pumps for concrete repair, geothermal drilling, fire protection, glass fibre reinforced concrete, and injection/grouting/filling.
Compressed-air screed conveyors operated at different locations, at the ground and higher floor levels of building construction sites
According to Binoj, Putzmeister’s best-selling range in the Middle East is its mortar plastering machines. They include mixing and pumping systems; different versions of worm pumps for processing premixed dry material with a maximum particle size upto 8 mm, mixer pumps and mechanical single piston pumps. Other common applications of Putzmeister mortar machines in the Middle East are semi-dry screeding, fireproofing and shotcreting.
The business of mortar machines in the plastering segment in the Middle East is a combined offering of material and machine. Contractors in this market usually work with suppliers that can provide the mortar machines as well as the premixed plastering material. Initially, a contractor gives an order to a manufacturer of premixed mortar for supply of material. The manufacturer responds with an offer to supply mortar machines along with the material, as a value added service. When the plastering work is completed, the contractor returns the machines to the supplier. While the outcome is similar to a rental business, the business model is entirely different because the material covers the rental costs of the machine. The contractor bears only the maintenance costs of the machines. This trend has made manufacturers of premixed mortar the biggest customers of Putzmeister. A less common business model exists in which contractors buy the machines directly from Putzmeister’s dealers and procure material from different suppliers.
“Premixed material manufacturers buy machines from Puzmeister and maintain a fleet for supply to construction sites. Their main objective is to sell their material. Having a stock of machines ensures that they win the contract for supply of material. They are complementary to each other as they drive material production and machine utilisation to ensure fast completion of plastering works. Generally, a plastering operation executed manually with six workers can cover an area of approximately 40-50m2 in an eight-hour shift. If a mortar machine is used with the same number of workers, it can cover up to 250m2 and more in the same shift, which is a minimum five-fold increase in plastering area. Therefore, it is in the interest of both parties to employ mortar machines to save time on plastering work,” says Binoj.
Binoj indicates that as the applications of mortar machines expand, there’s a need for contractors to train workers to operate and maintain such machines in the most efficient manner.
“We’ve identified skill and competency gaps in the market for machine utilisation, maintenance and site operations. We plan to address these requirements through training initiatives in the coming year,” says Binoj.
