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Bill Morley
Intermediate Member
Username: billm

Post Number: 4
Registered: 08-2005
Posted on Friday, May 12, 2006 - 06:16 pm:   Edit PostDelete PostPrint Post

I have asked a few brick suppliers to help me develop an understanding of the difference between hollow brick (ASTM C652) and face brick (ASTM C216). The reps have been reasonably adept at explaining the technical differences, but they have been no help in teaching me how a designer makes the design decision between the two types.

Is hollow brick simply a “residential” brick, and not as good as the more solid face brick? My question is in this context – modular size, 3-story office building, gyp or plywood sheathing on CFMF (L/600 max. deflection), Type N PCL mortar.

Does hollow brick tend to make a less water-resistant veneer? Does compressive strength ever become an issue (limiting factor)? Because there is less surface area, is there a relevant reduction in bond strength with the mortar?

There are a few inherent advantages to the hollow brick – lower product cost, less raw material, lower energy to manufacture, and cheaper to ship (lower unit weight). Do the disadvantages get offset by the advantages in a significant way?

In other contexts does the hollow brick compare differently to the face brick? For example, what if the studs were wood instead of metal? Would that influence the thinking about hollow brick vs. face brick? What if the building was multi-family type instead of office? Or what if the building was 6 stories tall instead of 2 or 3? How do differences like that influence the decision to use, or to avoid using, hollow brick?
Ronald L. Geren, RA, CSI, CCS, CCCA, MAI
Senior Member
Username: specman

Post Number: 259
Registered: 03-2003
Posted on Friday, May 12, 2006 - 06:37 pm:   Edit PostDelete PostPrint Post

From the Brick Industry Association (BIA):

Hollow Brick-A masonry unit of clay or shale whose net cross-sectional area in any plane parallel to the bearing surface is not less than 60 percent of its gross cross-sectional area measured in the same plane. See ASTM Specification C 652. Hollow brick are identical to facing brick but have a larger core area. Most hollow brick are used in the same application as facing brick. Hollow brick with very large cores are used in walls that are reinforced with steel and grouted solid. Larger cores or cells in hollow brick allow reinforcing steel and grout to be placed in these units whereas it would be difficult to do so with building brick, facing brick or some hollow brick.

Facing Brick-Brick made especially for facing purposes, often treated to produce surface texture. They are made of selected clays, or treated, to produce desired color. See ASTM Specification C 216. Facing brick are intended for use in both structural and non-structural masonry where appearance is a requirement.

Summary: Both are used interchangably, but large cell hollow brick is used where reinforcing with grouted cells (as in CMU) are used. Hollow brick can also be used in a facing condition where weight is a factor.
George A. Everding, AIA, CSI, CCS, CCCA
Senior Member
Username: geverding

Post Number: 157
Registered: 11-2004
Posted on Friday, May 12, 2006 - 06:39 pm:   Edit PostDelete PostPrint Post

Bill-

Hollow Brick is a similar discussion.
John Swink (Unregistered Guest)
Unregistered guest
Posted on Monday, May 15, 2006 - 03:14 pm:   Edit PostDelete PostPrint Post

Gentlemen:

ASTM C 652 Specification for Hollow Brick has been around for more than thirty years. It has been traditionally used for loadbearing clay masonry, and hollow brick are in no way inferior to C 216 face brick. Strength and durability requirements are exactly the same. Dimensional tolerances are similar, but differ slightly from C 216. The main difference between brick made under C 652 specifications is that a higher percentage of voids is allowed than for C 216. C216 allows up to 25% voids, where C 652 allows up to 40% voids, if certain conditions are met with respect to face shell and web thicknesses and void areas.

Acme Brick technical services laboratory as well as the National Brick Research Center (NBRC) located at Clemson University have both conducted tests on the physical properties of brick that meet ASTM C-216 with void area up to 25% and brick that meet ASTM C-652 with void area exceeding 25%; and have concluded that there is no significant difference in the performance of brick and assemblies related to compressive strength, water penetration and flexural bond.

Many leading manufacturers along with Acme Brick Company are moving toward producing brick that will conform to ASTM C-652 with voids greater than 25%. This specification change would reduce the amount of raw material, reduce the amount of fuel required during manufacturing and reduce the diesel fuel needed to transport to the job. Acme believes this move is the right direction when it comes to the use of our natural resources.

We encourage Architects, General Contractors and others when specifying brick to include ASTM C-652 and C-216. By including C-652 you will help us enhance our environment without compromising the integrity or performance of your building assembly.

On behalf of the Acme Brick Company thank you for your attention, consideration and your concern. If you have questions regarding this information or would like more details please feel free to contact your local Acme Brick Representative.

Sincere regards,

John E. Swink
Technical Services Engineer
Acme Brick Company
Fort Worth, TX

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