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|The HEMSS 3T experiment
|High-Explosive Model Structure Simulation (HEMSS) Program.
United States. Defense Nuclear Agency.
Bombich, Anthony A.
High-Explosive Model Structure Simulation Program
|Structures Laboratory (U.S.)
|Miscellaneous Paper (Structures Laboratory (U.S.)) ; SL-82-10
|This investigation was conducted in support of Phase III of the High-Explosive Model Structure Simulation (HEMSS) Program to evaluate the properties in compression of 2C4 grout when cured at high temperatures. The results of the investigation are to be used to validate: (A.) standard laboratory compression tests conducted on 2C4 grout cylinders taken during casting of large 2.13-m (7-ft) diameter HEMSS cylinders for earlier phases of the program, and (B.) other properties of the grout used in stress calculations based on the documented data on 2C4 grout. A grout cylinder designated HEMSS 3T was cast to simulate the field conditions of the HEMSS No. 3 cylinder cast in 1978. HEMSS 3T was a 2.13-m (7-ft) diameter, 1.09-m (43-in.) high cylinder insulated on top and bottom to simulate the thermal conditions of the 4.27-m (14-ft) high field-cast cylinders. Grout test cylinders were cast at the time of casting HEMSS 3T, and were cured in ovens based upon temperatures at two locations in HEMSS 3T. At one of these locations, 0.610 m (24 in.) from the center, the peak temperature of 95.5°C (204°F) was recorded. This compares with 102°C (215°F) recorded in the HEMSS No. 3 cylinder. At the second location, 0.914 m (36 in.) from the center, 79.4°C (175°F) was recorded. Cores were taken from HEMSS 3T at these locations. Compression tests (A series) on cast cylinders were conducted at 1, 2, 6, 13, and 28 days after placement. Longitudinal velocity tests were also conducted at the same times on both cast cylinders and the HEMSS 3T cylinder. Two series of static tests (C and B series) including triaxial, uniaxial, hydrostatic, and unconfined compression were conducted on cores taken from the two locations, respectively, in HEMSS 3T at 7 and 14 days age. Dynamic triaxial compression tests (SD series) were conducted on grout cores from the same location· as the C-series specimens; i.e., on cores 0.610 m (24 in.) from the center at 14 days age only. Computer simulations of the temperature and thermal strain achieved in HEMSS 3T were also conducted. As a result of this investigation, it was found that the HEMSS 3T cylinder successfully duplicated the conditions in the HEMSS No. 3 field-cast cylinder except for the slightly lower peak temperature. Generally, the measureable effects of high temperature on the grout properties were not significant. Large differences were found between measured and calculated strain values. Also, strains measured by two different strain gages were substantially different. These differences are attributed to differences in the coefficients of thermal expansion of the grout and the gages. Some fracturing or material degradation occurred near the periphery of the HEMSS 3T cylinders which was attributed to the thermal restraint effects of the corrugated steel culvert used as the forms. It is recommended that lubricated forms rather than corrugated culverts be used for the outer forms.
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