A silo mortar dispensing system is an engineering control that can reduce musculoskeletal disorders from manual material handling, including lifting, carrying and shoveling.  Mortar silos are delivered to the jobsite, and are equipped to be moved easily within minutes by a contractor's forklift as the masons move around the jobsite.  Material is loaded above the silo by means of a forklift.  Material is dispensed by gravity into the contractor's mortar mixer of choice from the bottom of the silo.  

Mortar silos are delivered to the jobsite, and are equipped to be moved easily within minutes by a contractor's forklift as the masons move around the jobsite.  The silo should be placed on level ground, downwind from the work area to avoid dust exposure.  Material is loaded above the silo by means of a forklift.  Material is dispensed by gravity into the contractor's mortar mixer of choice from the bottom of the silo.  The amount of material dispensed by the silo can be controlled with a cut-off handle.  The gravity feed is not dependent upon pressurized water hook-ups, electrical power, or gasoline motors.  Therefore, no external connections are needed.

The design of the silo is simple and highly efficient when dry mortar mix is being produced on site.  Silos can be used whether the worksite is small or large.  This system will greatly reduce the cost of labor and the amount of waste (sand, cement, paper bags).  Silos can be fitted with dust curtains, screw augers, set at various heights, and can be used with any mixer available on the market.  Some vendors of mortar mix will provide the mortar silo free of charge.

With a silo mortar dispensing system, pre-blended dry mortar ingredients, including sand, pigments and admixtures, are delivered to the jobsite in 3,000 lb bulk bags.  These bulk bags are then moved by forklift or boom truck lifts over a funnel-shaped silo, where they are dumped by pulling a hitch pin on the bag.  Silos are available in a variety of sizes and models, and hold from 1 to 10 bulk bags.  When the silo chute is opened, dry, pre-blended mortar is gravity-fed directly into the mortar mixer below.  The silos eliminate heavy lifting and twisting associated with the production of materials.

Job productivity is increased because laborers have fewer tasks to perform in order to produce mortar for the masons.  Many contractors believe these automated processes reduce material handling by mason tenders, freeing them to do other work, which can also free up jobsite space. 

When using a silo mortar dispensing system, it is important to assess the risk of silica exposure in the mortar mixing station and ensure that appropriate controls are in place. Silo systems do not eliminate the risk of silica dust exposure in the mortar mixing station; however, dust curtains are available.  Specific safety procedures must be followed when loading the silo, climbing the silo's ladder, and moving the system. The silo should be placed in a location that will minimize dust exposure to workers, and will facilitate the safe movement of vehicles/equipment needed to load the silo and handle mortar.

In addition to their ergonomic advantages, silo systems can also save space on congested jobsites, reduce material theft, and eliminate the problem of bag disposal (all bulk bags delivered to the jobsite are later removed by the supplier and either reused or recycled).

Mortar silo systems with built-in mortar mixers are currently available on the European market.  These devices are closed systems.  The silo is filled with the mortar components specified by the contractor and then sealed prior to delivery to the worksite.  Electrical and water supply connections are needed.  The mortar silo systems with included mortar mixers are pictured below.

Dan Anton, PT, PhD, ATC and Carlos Sanchez-Marin, DDS, MS – University of Iowa

• Reinforced Concrete
  • Mix concrete
    • Silica