Masonry Magazine January 1965 Page. 47
Special Report:
the progress of a new product being developed for the Masonry Industry
What's Happening To High Bond Mortars?
By A. A. "Bert" Hill, The Dow Chemical Co.
Many of you will remember the first announcement in late 1960 that The Dow Chemical Company and the Structural Clay Products Research Foundation, after several years of laboratory research, were going to begin field research on high bond mortars made with high bond liquid polymer. Quite a few of you have been personally involved with some aspects of this field research or development over the past four years including some 35 structures nationwide; now you may be interested to know that very geographically-limited marketing of Sarabond is just getting underway.
To refresh your memories, the concept of high bond mortars sprang from two bases:
through the judicious use of certain plastics materials, it is possible to considerably up-grade the physical strengths of portland cement/sand compositions, in particular bond strength, and,
the inherently-high strengths of individual masonry units such as fired clay bricks cannot be fully utilized by architects and engineers because these units are paired together with a material which is much weaker than they are; you may recall the old saying, "A chain is only as strong as its weakest link."
Putting high strength masonry units together with high strength mortar, then, opens up whole new structural horizons for masonry construction and enables masonry to be more competitive with possible alternate types of construction. The architect now has much more opportunity to use the inherent beauty and texture of masonry.
One of the problems which has bothered us a lot during our field development has been the workability of high bond mortar mixes, and we have examined literally dozens of workability additives in an effort to solve this problem. Very fortunately, we have in recent months been able to come up with workability additives which closely duplicate the action of lime in conventional mortars, and which do not hurt the strengths of high bond mortars like lime does. Several "mason productivity" tests carried out during 1964 have shown that the latest high bond mortar formulations readily enable the good skilled mason to maintain his normal rate of productivity. One of these tests involved the direct substitution of high bond mortar for conventional mortar in five brick-face houses, involving a crew of about 10 masons; another involved two two-story office buildings, one using ordinary mortar and face brick over a wooden framing, the other using the same brick and high bond mortar with no framing.
Currently, the materials used to make a high bond mortar are:
ASTM Type I or Type III portland cement
ASTM C-144-62T mason sand, washed clean
"A" Marble Dust, produced by Armco Steel Corp.
Sarabonde liquid polymer, produced by The Dow Chemical Company
Drinkable water
A comprehensive study of all these materials has indicated that the most variable one will probably be the (continued on page 49)