Hollow Brick Masonry

[JedClampett]

I just designed a one story building that I thought was going to be regular gray CMU and the architect threw me a curveball and said he meant it to be Hollow Brick Masonry. Dimensionally, he said it would be the same size as I assumed (8 x 8 x 16).I did some research and it looks like the design properties are the same. But I still have questions:
1. Is the stuff readily available? I went through some websites and it wasn't real clear if the normal brick suppliers carried the stuff.
2. For regular CMU, I would put control joints at 24 ft or so. But brick tends to expand. I could find recommendations for putting joints in veneer, but not the Hollow Brick. How often do I put in joints and do they need to be expansion?
3. Anything else I should watch out for? I use reinforced CMU lintels. Do my lintel designs change?

 

[AELLC]

Hopefully it is actually this half-high CMU:

http://www.nationalblock.com/westland-brick-the-look-of-the-future/

 

[Ron]

Have not seen full height structural clay masonry (8") except structural clay tile. Half-height is available as AELLC noted. Makes sense, since I'm sure the architect wants a "brick" look with a single structural wythe.

 

[JedClampett]

My mistake. My design was based on 8 x 8 x 16 CMU. It still worked for the architect's preference, which was 8 x 4 x 16 hollow brick.

 

[concretemasonry]

Jed -

To answer your questions as best I can -

1. You already found out is available and the 4" high units are as common as the 8" high units.

2. Control joints would be the same since the 4" high are made from the same materials and must meet the ASTM C90 standards for loadbearing units.

3. The lintel details may be slightly different of the architect wants to maintain the 4x16 wall pattern. If so you can have the lintel built in place with the first course having reduced height web (sawing or chipping) and a normal 4" high unit (1 course for an 8" high lintel or 3 courses for a 16" high lintel) laid on top and filled at thee same time.

If you specify a f'm for masonry compressive strength, you might not be able to find documentation of prism tests since they are rarely used or required. The usual prism strength requirement are usually exceeded by 25% to 50% because it is actually cheaper to make a stronger block. Since block are a zero slump product, adding water is the cheapest way to make a higher strength that is easier to handle and be exposed.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[hokie66]

Some advice here on provision of expansion joints in brick masonry.

http://www.gobrick.com/portals/25/docs/technical notes/tn18a.pdf

Brick masonry blocks would, I think, exhibit the same degree of long term expansion that regular bricks would, made with same clay. There is a lot of variation between different types of bricks, and testing can be done to evaluate this expansion potential. If the bricks are grassed for a period of time, this allows some of the expansion to occur and theoretically lessens the need for jointing, but having seen the results of brick growth, I would not skimp on the joints.

 

[concretemasonry]

If the architect insists on clay block and not concrete masonry units, you will just have to make sure they are available wherever you are. The price, especially with the freight required would be quite expensive, but they would equivalent to CMUs for strength, but do have a long term expansion over time. the 20' you planned on would probably be satisfactory. If you have reinforcement, make sure there is a core pattern that will allow grouting.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.