TO: Dr. Clifford K. Beck
FROM: R. L. Murray and A. C. Menius
SUBJECT: Reactor Concrete Tests (Preliminary Report)

This report summarizes the recent investigations of reactor concrete
mixes by Professor C. R. Bramer of the Civil Engineering Department. We are
glad to report that the experiments were very successful, thanks to Mr. Bramer's
ingenuity.

Two shipments of barytes aggregate were tested.

• 1. Sweetwater, Tennessee - supplied by L. A. Woods.
• 2. Cartersville, Georgia - supplied by New Riverside Ochre Co.

In previous tests, the mortar had failed to set, which was attributed
by Oak Ridge people to be due to the large amount of water that is normally
added to make the consistency proper for pouring. Thus in the present experi-
ments, efforts were made to minimize the water content.

As the basic proportions of materials, the Oak Ridge Figures for a cubic yard
were used:

• Barytes	3970 lb.
  Colemanite	400 lb.
  Portland Cement	830 lb.
  Water	310 lb. (37.5 gal.)

The following table gives the composition of the several batches used
to make test cylinders:

A. June 19:
• One seventeenth (1/17) of the above weights were taken. Assuming that the
  Sweetwater barytes coarse was 3/4" ASTM and the fine was 3/8," the latter
  was acreened to remove all material smaller than 16 mesh. The ratio of
  "coarse" to "new fine" was then taken as 16.6 to 1. The weights (in lb.)
  resulting were:

• • Coarse barytes	220
    New fine barytes	13.25	Air Temperature 80°
    Colemanite	23.5	Humidity 70%
    Type III cement	48.8

• One cylinder was made with 21.5 lb. of water which was 11.8% more than the
  Oak Ridge specification, the slump was negligible. A second was made with
  an arbitrary added amount of water giving a one-inch slump.
• The first cylinder set up slowly, and after a week is still not completely
  firm; the second was even softer.

B. June 21.
• The fraction of the cubic yard mix used in this case was 1/85. The alterna-
  tive of type II cement was tried, with the weights below:

• • Coarse barytes	44.05
    New fine barytes	2.65	Air Temperature 82°
    Colemanite	4.70	Humidity 76%
    Type II cement	9.80
    Water	3.64 (Oak Ridge)

C. June 21.
• The fine barytes was not screened in this test. Proportions were adjusted
  somewhat:

• • Coarse barytes	36.05
    Fine barytes	10.65	Temperature and Humidity as
    Colemanite	4.70	above.
    Type II cement	9.80
    Water	4.14 (11.4% over specification)

• Neither of these mixes have become firm or show any signs of even doing so.

D. June 22.
• On the assumption that the dissolved colemanite inhibits the portland cement
  action, the colemenite was not added until the mixture of cement, aggregate
  and water had set for 45 minutes. The Georgia barytes was used.

• • Barytes	46.70	Air temperature 82°
    Colemanite	4.70	Humidity 75%
    Type III cement	9.80
    Water	4.00 (11% excess)

• This mix set up in about 24 hours and after three days is judged to be quite
  adequate.

It would be concluded tentatively that:

• a. Georgia Barytes is a preferable aggregate, from the standpoint of
  uniformity of gradation (and cost).
• b. Type III cement should be used.
• c. Special "late" mixing of colemanite is needed.
  Professor Bramer states that a contractor can do this.

The specific gravity was measured to be 3.4.