A treatise on concrete, plain and reinforced : materials, construction, and design of concrete and reinforced concrete; 2nd ed. . No. ofBri-quettes Tensile Strength, lb. per sq. in. 7 d. 28 d. 3 mo. 6 mo I yr. Water in laboratory Air in laboratory Out doors, below freezing. 202080 268298139 304352238 359364344 370392435 401 517627 *Kindly furnished by Mr. Richardson for this Treatise. 322 A TREATISE ON CONCRETE The briquettes were made in sets of 5, consequently 4 experiments areshown for water and air in laboratory, and 16 for out doors. In France similar results have been reached by Mr, P. A
A treatise on concrete, plain and reinforced : materials, construction, and design of concrete and reinforced concrete; 2nd ed. . No. ofBri-quettes Tensile Strength, lb. per sq. in. 7 d. 28 d. 3 mo. 6 mo I yr. Water in laboratory Air in laboratory Out doors, below freezing. 202080 268298139 304352238 359364344 370392435 401 517627 *Kindly furnished by Mr. Richardson for this Treatise. 322 A TREATISE ON CONCRETE The briquettes were made in sets of 5, consequently 4 experiments areshown for water and air in laboratory, and 16 for out doors. In France similar results have been reached by Mr, P. Alexandre* asto the effect of temperatures slightly above freezing. Mr. Charles S. Gowenf also has concluded from his tests that there isno indication that freezing reduces the ultimate strength of the mortar,although it delays the action of setting. The effect of different uniform temperatures upon npat cements andmortars is illustrated in Fig. iii, which is selected and adapted by theauthors from a series of experiments by Mr. J. E. HowardJ at the Water-town Arsenal. The results with both neat cements and mortars show but. f IG. 111.—Strength of Neat Portland Cement Mortar, 2-inch Cubes,Set in Air at Different Temperatures. {See p. 322.) slight increase in strength while the specimens are maintained at 0° Fahr.(—18° Cent.), but a decided increase in strength as soon as they are sub-jected to a higher temperature. The zero cubes were removed from thefreezer and allowed to set one day at 70° Fahr. (21° Cent.) before break-ing. Cold retards setting. Prof. Tetmajer§ found, for example, that i: 3Portland cement mortar which attains its initial set at 2f hours and itsfinal set at 8§ hours when mixed at 65° Fahr. (18° Cent.), at a temperatureof freezing reaches its initial and final set at 21 and 38 hours respectively. *Annales des Fonts et Chaussees, 1890, II, pp. 302 and American Society for Testing Materials, 1903, p. 393.{Tests of Metals, U. S. A., 19
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