Point Loading - Uniformity is Key with CEB

One of the attractive aspects of CEB is the fact that you can use a thin slurry to lay them, rather than a thick mortar joint. As I continue to explore building with CEB, I have determined that uniform block height is essential if mortar joints are not planned to be used. Eliminating mortar joints, like those used with Adobe, Brick or cement block, reduces the amount of skill and labor required thereby enabling the DIYr and saving resources.

As CEBs are layed/stacked, and courses rise, the blocks in the lower courses, experience increased downward pressure. If the blocks are flat against each other, or if they sit in a "bed" of mortar allowing them to lie flat, then the downward pressure in any area of the horizontal block faces is fairly equal. As mentioned equal pressures occur due to either 1) a mortar joint, or 2) uniform block height.

Since one of the benefits of a CEB wall is a thin slurry set thereby reducing labor and skil, uniformity then becomes key. If blocks are not uniform in their height, then as courses rise and downward pressures increase, the chance for "Point Loading" increases. As shown to the left, point loading occurs when one specific point or area of a higher coursed block carrys more of the dowward force due to a non-uniform lower block. The lower block has only one "point" that it is in contact with the upper block.Carrying the forces in this one area, and not spreading the load across the face of the block, can cause the block to crack or fail, thereby eliminating the effectiveness of the wall.

My next post with focus on two methods used in block production, vertical and horizontal pressing of the block. Each has pros and cons when it comes to their effect on Point Loading.