Before incorporation into a concrete, the surface of the treated 
aggregate was rinsed to ensure a good bond between it and the cement 
paste. Several methods of rinsing were evaluated, including steam, hot 
water, cold water, trisodium phosphate solution, mineral spirits, and 
acetone-water solution. Based on the compressive strength of concrete 
made from aggregates rinsed by these methods, the acetone:water ratio of 
90:10 by volume was selected as the method of choice and was used for 
all treated aggregate employed in this investigation. In this procedure, 
3 kg of aggregate are shaken with 1 kg of solvent for 1/2 to 1 minute. 
The solvent is immediately decanted from the aggregate which is again 
spread on newspaper or burlap to complete solvent evaporation. The 
finished aggregate is either used immediately or stored in sealed con- 
tainers until ready for use. 
Dry Toxicants in Cement Mix 
For some of the tests, cuprous oxide (Cu,0) was added as a dry 
ingredient to the concrete mix. It was added by itself and in combination 
with TBTO, but was not impregnated into aggregate. 
Methoxychlor, a chloro-organic compound, was also investigated. 
It, too, was added to the concrete mixture as a dry ingredient, both by 
itself and in combination with triphenyltin hydroxide (TPTH) and Cu,0. 
Antifouling Coatings 
Two types of coatings for concrete cylinders were tested. With 
one, an organotin-polysiloxane polymer coating was applied by brush to 
untreated cylinders. With the other, a proprietary TBTO-impregnated 
elastomer was wrapped around and cemented to untreated cylinders. 
TESTING PROCEDURES 
Preparation of Concrete Specimens 
The amounts of the constituents of the concrete are given in their 
order of addition: 
40.3 lb expanded shale aggregate (weight before impregnation) 
62.2 lb sand 
Zeal water 
47.0 1b Type II portland cement 
The wet concrete was mixed 3 minutes in a 1-3/4 ft?-capacity pan-type 
mixer. The slump was then measured; adjustments were made, if neces- 
sary, by adding more water. The finished wet concrete was then placed 
into 3-in.-diam x 6-in.-long cylinder-shaped molds to half fill them. 
The molds were placed on a vibrating table for several minutes and then 
filled to the top. The vibration was resumed and continued for several 
more minutes, after which the tops of the molds were finished with a 
trowel. The specimens were then placed in a 100% relative humidity 
