Surface Bonding Cement 1

[omoreno1]

I had a contractor ask about using surface bonding cement mortarless masonry. Has anyone ever heard of this.. or knows if ACI 530 even covers these type of situation. I would suspect this would only be a remotely valid in a low wind and low seismic area.

 

[concretemasonry]

Surface bonded masonry has been around for about 30 years. I think it was developed by Owens Corning originally. Now, there are several companies producing surface bonding coatings. There have many many code approvals.

It never took off because the supposed cost advantages never were realized, but is good for certain applications.

Dry stacking of masonry is not as cheap or fast as expected. Some unskilled people felt that if they had started with no real masonry skills, they could learn enough to build a reliable conventional masonry wall before they were finished. It is very difficult to stack up block vertically 8 feet before coating.

In comparison to conventional concrete masonry -

1. The compressive strength is less and variable because of the point loading from dry stacked units.

2. Flexural strength is greater.

3. Shear strength is variable.

4. Proper mixing is critical and improper mixing can have a drastic effect on the results.

5. Quality control of the wall is very, very difficult because it depends on proper application and the ability to maintain an adequate coating thickness. Conventional concrete masonry is difficult to ruin if you can build a wall vertically with no voids in the joints - Mortar really has little influence on the strength and the units are cured before delivery, so the result is quite predictable.

Dick