“A” block increases productivity

Starling Johnson

Meeting Market Demands

Mason contractors are especially receptive to an “A” shaped unit on jobs with extensive use of reinforcing steel, such as prisons, or on jobs with rebar used at high elevations or in tight job sites. Savvy contractors realize labor savings in not having to cut the end of a block and the reduced risk from lifting units up and over rebar.

In order for a modified “A” block to be embraced by the design community, it must represent a faster, safer and more cost effective alternative to traditional masonry construction and meet or exceed the energy performance of competing wall systems. It is primed to achieve a more energy efficient wall system.

As part of the development process, the production team welcomed 43-year masonry expert, customer and neighbor, Mason Contractor David Troutman into a conversation about a new block concept. His feedback was incorporated into the final design of what would become the new modified “A” block. Troutman immediately understood the productivity gains that could be realized with this new “A” block and was eager to be the first to use it on a project.

Slide Around Rebar

Troutman was initially drawn to the idea of a modified “A” block due to the ease of working around reinforcing steel. In the NC seismic zones, it’s becoming increasingly common for engineers to require rebar lengths over 6′. Masonry crews are challenged to maintain productivity while having to lift CMU up and over these heights. When using an “A” block, however, masons can slide the units around the rebar and therefore keep scaffold walk boards closer to the level of the wall to optimize productivity.

Easier to lift lightweight A secondary benefit was the reduced weight of the modified “A” block produced with lightweight aggregate and less web area. Used to laying standard lightweight masonry units, Troutman noticed that his crews were less tired and more productive at the end of the day when using the lightweight “A” block. Furthermore, a typical mason could lift the 12″ block with one hand and not have to put down his trowel, significantly increasing production. There seemed to be no learning curve for the masons.

Labor Savings/ Increased Productivity

Labor savings are realized in never having to cut the end of a unit. Safety is increased as masons do not have to lift the block higher than the course they are laying.

According to NCMA TEK 4-1A, Productivity and Modular Coordination in Concrete Masonry Construction, a mason can lay approximately 100 50-lb units per day and approximately 175 20-lb units per day. While initially concerned about breakage due to the open end and thin webs and face shells, Troutman did not experience a higher waste rate.

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