Solution Summary: Mortarless Masonry Wall Systems
Mortarless masonry wall systems are comprised of concrete masonry units laid dry and subsequently grouted, partially grouted, or suface bonded. Applications of mortarless wall systems include basement walls, foundation walls, retaining walls, exterior above-grade walls, internal bearing walls and partitions.
The construction of masonry wall systems is possible without the use of mortar. Comprised of fabricated Concrete Masonry Units (CMUs) often referred to as "dry-stack units" that are surface bonded with fiber cement, these structures are often included in the following system types:
-grouted, partially grouted or surface bonded
-unreinforced, reinforced, or pretressed
Specifically designed units for dry-stack construction are available in many different forms. The most sophisticated designs incorporate face shell alignment features that make units easier and faster to stack plumb and level. Other units are fabricated with a combination of keys, tabs or slots along both horizontal and vertical faces so they interlock easily. Physical tolerances of dry-stack concrete units are limited to +/- 1/16 in. (1.58mm.) which precludes the need for mortaring, grinding of face shell surfaces or shimming to even out courses during construction. Interlocking units placed in running bond resist flexural and shear stresses results from out-of-plane loads as a result of keying action.
The interlocking features of dry-stack units improve alignment and leveling, reduce the need for skilled labor and reduce construction time. Floor and room systems can be supported by mortarless walls with a bond beam at the top of the wall which expedites the construction process.
Dry-stack concrete masonry units can be used to construct walls that are grouted or partially grouted; unreinforced, reinforced or prestressed; or surface bonded.
Need to get permission to upload all or portions of National Concrete Masonry Association TEK manual 14-22 (2003), Design and Construction of Dry-Stacked Masonry Walls. Available at http://www.ncma.org/map_pages/state_finder.cfm
- Musculoskeletal disorders and worker fatige due to manual materials handling
- Tendonitis and carpal tunnel syndrom due to stressful hand and wrist activity
- Silicosis and lung cancer due to exposure to crystalline silica dust
- Burns and allergic reactions due to skin contact with chemicals
- Hearing loss due to noise exposure
How Risks are Reduced:
- Mortar mixing is eliminated. Mortarless wall systems eliminate hazards associated with mixing mortar, including manual materials handling, silica exposure, skin contact with chemicals and noise exposure.
- No need to deliver mortar to the work area. Mortarless systems eliminate the task of transporting mortar from the mixing station to the wall. This reduces laborers' risk of musculoskeletal disorders due to manual materials handling and skin problems due to contact with mortar.
- Troweling is eliminated. Mortarless masonry eliminates the stressful hand and wrist activity involved in applying and smoothing mortar.
- Frees both hands for handling block. Eliminating the trowel enables masons to lift and place block with both hands, reducing the risk of musculoskeletal disorders associated with laying block.
Effects on Productivity:
- Faster installation. Mortarless concrete masonry units can be installed up to 10 times faster than conventional block, dramatically reducing labor costs.
- Easier installation. Because dry-stacked, interlocking block self-aligns and self-seats, it can be laid by semi-skilled and unskilled workers, increasing the productivity of apprentices and laborers.
- All-weather construction. Mortarless systems can be stacked in all weather conditions, speeding construction.
Care must be taken in evaluating risk reduction with substitute building systems, since many variables are involved. For example, trowling of surface bonding agents, or other tasks that are introduced may also introduce unrecognized strains or risks of injury.
A higher block laying rate may lead to increased arm, shoulder and back exhaustion. Job rotation during a shift and more frequent, shorter breaks should be considered as means of preventing injury.
To obtain information, visit http://www.quikrete.com or contact 1-800-282-5828