Masonry Magazine January 1968 Page. 26
Fire Test Report
4 HOURS WITH FRINGE BENEFITS
On September 28-29, 1967, the Underwriters Laboratories, Inc. performed a fire test on a 10 wide, 10 high, masonry wall erected using 8" x 8" x 16" concrete block made using an expanded slag aggregate. This panel had cores on one half filled with water-repellent vermiculite masonry fill insulation and the cores on the other half of the panel remained vacant. The fire test was conducted in accordance with ASTM Specification E119. The wall carried a full design load throughout the entire test.
The intended purpose of this test was to determine if a concrete masonry unit that had been certified as a 2-hour rated block could be upgraded in classification to a 4-hour rating by filling the cores with vermiculite. At the outset it was agreed that the end points that would be reached for the unfilled portion would be used as a base and the filled side would have to go 2 hours beyond that point if we were to obtain a successful upgrading of the 2 hours in classification. As the test progressed the surface temperatures on the face of the block wall away from the fire on the unfilled side did not exceed their limits until the test had progressed some 3 hours and 20 minutes. According to the ground rules the filled portion of the wall would then have to successfully pass an endurance time of 5 hours and 20 minutes which, needless to say, caused a great deal of concern to those who were present. As the test progressed beyond the 4-hour time period it became increasingly evident that the thermocouple readings on the side of the wall panel filled with vermiculite were not increasing at a rate that would indicate failure before the 5 hour and 20 minute period. In fact, the time of 5 hours and 20 minutes was passed with all of the thermocouples on the filled portion of the wall still below 210", and the allowable average was 320° F. After 5-1/2 hours into the test there was a great deal of concern for the condition of the furnace and the test frame and hydraulic system that was imparting a load on the wall, because at the outset it was not anticipated that this test would run this long. It was agreed that regardless of how close we were to the end points after 6 hours the test would have to be shut down.
The wall panel the morning after the fire test with hydraulic jacks maintaining full design load is being prepared for a double load test. A magic marker was used to define the fine hairline cracks that developed in the wall panel.
At 6 hours and 5 minutes into the test the hottest thermocouple on the filled side of the wall was still below 220°F. (over 100 below the value that all thermocouples would have to average out before failure). The fuel source was shut off at 6 hours and 5 minutes into the test and the wall was immediately pulled away from the furnace for a fire-hose stream test. As the wall came away from the furnace, still intact in the test frame with the full design load being carried by the wall, the surface of the wall closest to the fire glowed in brilliant incandescence a brilliant yellow orange in color. As the fire hose stream struck this red hot surface the thermal shock was audible, similar to firing a gun in a closed room. The wall successfully maintained its integrity and held the full design load through the 5-minute firehose stream test, which at this stage of the game seemed like an eternity rather than 5 minutes. The wall was allowed to stand overnight, still carrying a full design load, and the following morning the load on the wall was increased to twice the design load to check out the wall to see if an adequate safety factor was still maintained after this rigorous and torturous test. The wall successfully held double the design load.
The success of this test places an 8" concrete masonry wall that is insulated with vermiculite in the category of killing two birds with one stone. Besides being a wall that is insulated with respect to conventional heating and air-conditioning loads, it is also a wall that can obtain a 4-hour fire rating. Additional information is available from the Vermiculite Institute, 208 South La Salle Street, Chicago, Illinois (60604).
masonry • January, 1968