CEMENT--SET AT DIFFERENT TEMPERATURES.
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CEMENTS WHICH SET IN AIR AT DIFFERENT TEMPERATURES.
This series of experiments was made with a number of brands of domestic and foreign Portlands, a slag cement, and some natnral cements. The several batches of material were gauged with sufficient water to insure a mixture of the consistency of ordinary mortar for stone masonry. Immediately after mixing, the material was put into 2-inch molds, with a few cubes of larger size and a number of tensile briquets. There were three general groups, one of which set in the open air of the testing laboratory at ordinary atmospheric temperatures, given in the details and tabulations as 70° I. I he specimens belonging to the other two groups were placed in a cold-storage warehouse, where they remained the different intervals of time noted in the tests. One group was placed in a room known as a “Cooler, m which the temperature was maintained in the vicinity of 39°. Hie other group was placed in a room known as a i reezei, in whu h the temperature is kept in the vicinity of 0° F., seldom varying more than 5° in either direction from this point, the thermometer more frequently indicating a temperature a few degrees below than above
26Each group was exposed to its prescribed temperature as soon after mixing as practicable. Specimens intended for the “ Freezer’ were mixed on cold days, with the thermometer in the vicinity of 15 to 20 F at once exposed to this temperature, and after they were frozen were removed from the molds and taken to the cold-storage warehouse. The plank molds were generally cooled below 32° F. before using. In these tests it was intended to'freeze the material as soon as practicable after mixing, and use mixtures as wet as ordinarily employed in construction. Specimens exposed to zero temperature while setting were allowed at least one day in air at about 70״ F. immediately before testing..