Masonry Magazine February 1997 Page. 22
Silo Mortar Delivery Systems
by Brian Camey
Bringing you Quality, Efficiency and Consistency
Masonry construction dates back as early as 4000 B.C. when sun-dried brick were stacked and parged with mud. Proven to be a viable form of construction, this building technique would be used on such structures as the pyramids of Egypt and the Great Wall of China.
Since that time, the masonry industry has experienced great change, improving the means and methods of masonry construction. In 1756 hydraulic lime was introduced, 1824 brought portland cement, while the 1940's saw the development of powered mortar mixers. For most members of the masonry industry, a job site without a 10 cubic foot paddle mixer is inconceivable, not to mention inefficient.
Among the most recent innovations impacting the masonry industry are silo mortar delivery systems. The high costs of labor, job completion demands and concerns for job site safety (back injury) are factors which have fostered the inception of bulk mortar systems. The "silos", as they are commonly referred to, are based on European technology dating back to the 1970's. Today, there are essentially three separate concepts for silo systems that have successfully earned the respect of the masonry community. Two methods involve "silo-mixed" mortar utilizing both on site electrical and pressured water hook up. These particular silos are either single-compartment or multi-compartment models that are filled at the plant and delivered to the site. The third silo mortar system is an entirely different design entailing a collapsing, relocatable silo charged with 3,000 pound bulk bags which are pre-blended to meet appropriate ASTM specifications. This method places the contractors' mixer below the silo, which dispenses material to be mixed with the appropriate amount of water. Multiple products can be mixed on site.
Single Compartment Silo Systems
The material in the single compartment silo is preblended dry at a factory using a batching process that includes oven dried sands. Once a truck delivers the silo to the job site, the utilities are attached and the control systems is preset to dispense the dry mix with water into the screw mixer chamber. The compartment is refilled via bulk tanker using pneumatic principles to blow the silo full. The initial delivery is only half full due to applicable road restrictions. Pushing a button starts the mixing process and mortar is dispersed into the contractors tub.
Multi-compartment Silo Systems
Multi-compartment silos differ from the former in that damp, loose sand is loaded into a larger compartment.