Memorandum from Raymond L. Murray to Dr. C. K. Beck
June 14, 1951
June 14, 1951
Dr. C. K. Beck
cc: A. C. Menius
In accordance with your request, I checked with Dr. Kitzes of
ORNL and his assistant, Mr. Gallaher, on the Coleminite concrete.
Their remarks and recommendations are reproduced below.
1. The basic problem in the setting of this concrete is that
the boron compound dissolves in water, resulting in a solution that
inhibits the action of Portland cement. The amount of water added
must be carefully controlled, and the mix prepared in a much dryer
state than is conventional in concrete practices, and in fact, giving
such a constituency that contractors are very much alarmed. The
added water should be as cold as possible because of the solubility
2. The exact proportions at the various constituents have been
established by experiment; once they are found and the procedure for
preparation followed religiously, a reproducible satisfactory concrete
is obtained. (To my untrained eyes the test blocks I was shown looked
3. The two mixes that have been used successfully were:
- a) that for which we have specifications: Barytes 3970 lbs,
Coleminite 400 lbs, Portland cement (preferably type III) 830 lbs,
water 310 lbs (maximum), which is designed for poured sections, using
Coleminite sand. The aggregate size specifications are: 1" and 3/8"
aggregate ASTM in the ratio at about 16:1 coarse/fine. All material
of size passed by a 16 mesh screen is removed from the aggregate. The
water content is best specified by the maxim of a 2" slump, rather
than by the weight listed above. This test takes care of the tempera-
ture and humidity conditions at the tine of pouring.
- b)that used with the Coleminite dust, which is more soluble
than sand and requires addition of Lumnite as a setting agent. The
mix is fed to a block machine with several thousand pounds pressure.
The data and instructions to S. M. Barres are given below almost ver-
batim. Basically they should apply to either mix listed in this note,
according to Kitzes.
|3/4" ASTM (Coarse)||3490||64.2
|Type III Cement (Hierly)||460||8.5
|Water||< 55 gal||8.5 (2" slump)
- 1. Blend dry the Portland cement, Lumnite, and Coleminite thoroughly
prior to adding to mixer.
- 2. Blended mixture can now be handled as ordinary Portland cement.
- 3. Temperature of H2O < 70°F.
- 4. Only specified amount of water added!!
- 5. Mixing time, 3 minutes.
- 6. Pouring completed withing 30 minutes.
- 7. Mixer washed thoroughly after each pour.
- 8. Curing to start immediately after forms removed.
Wet burlap or sand 7 days. No direct stream of H20 used.
Raymond L. Murray