CHAPTER If, SECTION 1 maintain the highest quality concrete, all aggregates were thoroughly tested before approval for use in concrete. a Jig Concrete cylinders were packed in wet sawdust for 48 hours, the time required for shipment to the test laboratory at Elmer. A total of 1483 test cylinders were taken from 32,500 cubic yards of concrete. The average compression strength of all test cylinders for the required strength of 2000 psi, 2500 psi, and 3000 psi was 2500 psi, 2700 psi, and 3700 psi respectively. No significant variation was noticeable between atolls. Inspection of all construction at EPG was the responsibility of the Chief Inspector at Elmer until construction started on Bikini Atoll. At that time another Chief Inspector was assigned at Nan and assumed responsibility for all construction at the atoll. Similarly, when construction got under way at Johnston Island, a Chief Inspector and inspection force were organized at that location to assume responsibility for all inspection functions. The inspection of construc- tion of Weather and Rad-safety Stations was the responsibility of the Chief Inspector at Elmer. Supplementing the Inspectors, certain Engineering Specialists were assigned specific inspection duties; i.e., an Assistant Engineer was selected to inspect all barge-type construction. eS: beet Aa (Neg. No. W-V-246-8) a eneans . ~ & . sere phew oi Figure No. 2-8. Compression Test on Concrete Cylinder. The Materials Testing Laboratory on Elmer was responsible for testing aggregate, cement, concrete, soils, and other materials requiring control in construction; for testing materials required in support of any special studies the Department was required to make; for surveillance of aggregate stockpiling; and for assistance to Field Inspectors during concrete placing. To provide adequate and effective coverage and en- sure adherence to specifications. field laboratories were established at Site Nan for Bikini Atoll and at Johnston Island. These field labora- tories operated directly under the supervision of the Test Laboratory Engineer at Elmer. Aggregates for concrete mixes were composed of crushed coral rock and fine coral beach sands. Variations in the physical qualities of coral rock required the preparation of 41 mix designs at Eniwetok Atoll, 17 at Bikini Atoll, and 6 at Johnston Island. The mix designs for Johnston were made at Elmer, using sample ingredients shipped from there. For the aggregate shipped from Hawaii for use at Johnston Island, the on- site field laboratory determined the specific gravity, and the design mix furnished from Elmer was adjusted accordingly. In order to _ Page 52 (Neg. No. W-V-246-6) Figure No. 2-9. Shear Test Equipment, Test Lab — Elmer.