upon methods of accounting, it is believed that the published prices 
of ready-mixed concrete would provide an adequate cost index. These 
prices reflect all costs associated with the production of the final 
product, that is, production of sand, gravel, cement, water and the 
appropriate combination of these materials to formulate plastic concrete 
ready to be placed in molds. 
Table 4.1 shows prices per cubic yard of concrete for the period 
1965 through 1969 for eight major cities of the U. S. The price of 
concrete during this period has held remarkably steady for the U. S. as 
a whole. The national average (based on 22 major cities) increased from 
$14.27 in 1965 to $15.62 per cubic yard in 1969. In 1969 the lowest 
price per cubic yard was reported for Atlanta at $12.75; the highest, 
in New York at $21.65. 
The cost of concrete in place is another story, and includes all 
costs of planning, design, formwork, reinforcing metals, rental for 
land use, labor, and form removal. Until a specific structural concept 
has been adopter and designed, such costs are impossible to esimate 
with accuracy. 
PRODUCT LON 
Production Plants 
Generally speaking, it is believed the probabilities of utilizing 
existent production plants for aggregate, cement, and concrete at a 
CONUS site are very good. Regardless of where the MOBS construction 
site is likely to be - CONUS or remote - existent cement plants have 
ample capacity to supply required amounts of cement. About the only 
reason for considering a new cement plant would be the discovery of a 
prime source of raw materials in proximity to the construction site. 
In this event, nearly any one of the existent large cement producers 
would literally jump at the chance to establish a new cement plant. 
Aggregate Plants. Aggregate producing plants are generally custom 
designed. The type of equipment generally needed includes mining and 
excavating machinery, rock crushers, elevated storage bins, aggregate 
size separators, belt conveyors, bucket conveyors, and facilities for 
washing aggregate. Specific equipment needed is well illustrated and 
specified in the Handbook and Purchasing Guide for the Nonmetallic 
Minerals Industries (Rick, 1969), issued annually. 
Concrete Plants. Concrete plants are of two general types. 
One type includes concrete mixers set up in such a way that freshly 
mixed concrete is delivered bymeans of a large dump bucket on a cable 
supporting system direct from the mixer to the actual point of emplace- 
ment. The construction of Hoover Dam exemplified this system. Such a 
system is economical only where large quantities of concrete are to be 
fabricated and delivered to a site close to the plant. Establishing such 
a plant might be economical for MOBS. 
