

Solution: AAC (Aerated Autoclaved Concrete)

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	Description:	Aerated autoclaved concrete (AAC) block is a lightweight concrete block that can be used as an alternative to standard concrete masonry units (CMU) in certain applications, such as low rise loadbearing buildings, partition walls, infill walls, shear walls, etc. AAC has several properties such as: a) the ability to provide thermal and acoustic insulation, b) lightweight, c) energy conservation, d) durable, e) fire and pest resistant, and f) versatile and easy to use. Vertical reinforcing can be installed in cored units and horizontal bars can be installed in bond beam units. Standard AAC blocks weigh approximately 30lbs and are usually 24" long. They are available in different shapes and sizes: 1) AAC standard blocks, 2) AAC "O" blocks, 3) AAC "U" blocks, 4) AAC open end blocks, and 5) AAC jumbo blocks. AAC blocks are fabricated from a mixture of lime, sand, cement, gypsum, water and aerated agent. The exterior and interior walls are easy to finish, and they can be painted, plastered, tiled or left exposed. AAC is most commonly used for interior walls and structures of two stories or less. AAC is considered to be environmentally friendly for several reasons. The manufacturing of AAC material does not release any harmful gasses or CFCs, and all waste products can be easily recycled. Also, AAC blocks greatly reduce the amount of energy required to heat a building. The material properties of this material allow it to behave like a thermal mass storeroom, storing solar energy and releasing it over time. More Detail
	Risks Addressed:	Musculoskeletal disorders and worker fatigue may result from lifting heavy materials. Lifting lower weight materials can reduce the risk of back and related injuries.
	How Risks are Reduced:	Using lightweight block such as AAC during manual material handling reduces strain and loading on mason's backs. If the weight of the materials being handled is reduced, then workers' risk of developing low back pain and related musculoskeletal disorders (MSDs) is also reduced.
	Quality of Evidence (Risk Reduction):	Independent published studies have found a risk reduction. Safety and health experts believe there is a risk reduction.
	Quality of Evidence Explanation (Risk Reduction):	Independent studies have shown a reduction in exposure to known risk factors for low back pain while using lighter weight materials. The Construction Safety Association of Ontario analyzed masonry activities to determine their potential for causing musculoskeletal disorders. The study revealed that working with standard concrete blocks (12 x 24 x 6 inches, 35-45 pounds) can expose masons to a high risk of low back injury. Back stress was reduced when the weight of the block was decreased. The study also showed that adding grips to the block reduced stress as well. Anton et al. at the University of Iowa conducted a laboratory study to determine whether lightweight concrete block reduced physiological loads compared to standard weight block. Twenty one masons constructed two 32 block walls, seven courses high, entirely of either standard weight block or lightweight block. Muscle activity from arm and back muscles, and heart rate was measured during the wall construction. In general, muscle activity was slightly lower when masons were laying lightweight block compared to standard weight block. Safety and health experts believe that masons will be less likely to develop musculoskeletal disorders of the back and shoulder if they are able to substitute AAC block for regular CMU.
	Effects on Productivity:	There may be an increase of productivity and labor savings due to the lightweight property of AAC.
	Quality of Evidence (Effects on Productivity):	Manufacturers or vendors have reported an increase in productivity. Safety and health experts believe there is an increase in productivity.
	Quality of Evidence Explanation (Effects on Productivity):	Manufacturers of light weight aggregate report a 15-30% increase in productivity. Labor costs may be slightly less because lighter weight blocks may allow faster installation. Health and safety experts believe reducing the risk of developing musculoskeletal disorders may lead to increased productivity because: 1) masons can lay block for longer periods with fewer breaks and less fatigue, and 2) there may be a reduction in lost time injuries.
	Return on Investment:	To calculate the return on investment (ROI) for your specific application, please visit our Return on Investment Calculator. While a specific ROI example has not been developed for this particular solution, the ROI Calculator provides a useful tool and guidance on how to generate your own on investment analysis.
	Availability:	E-Crete For purchasing information visit http://www.safecrete.com/ or contact 1-866-508-5803 SafeCrete For purchasing information visit http://www.safecrete.com/ or contact 1-706-965-4587 or sales@safecrete.com Litebuilt For purchasing information visit http://www.litebuilt.com/ or contact info@litebuilt.com
	Contributors:	Dan Anton, PT, PhD, ATC – Eastern Washington University, and Carlos Sanchez-Marin, DDS, MS – University of Iowa
	Hazards Addressed:	Residential Construction Lay block or brick Overhead work