108 



Coefficient of Expansion of Brick. 



C. V. Sea STONE. 



luasiiiuch as brick is used extensively as a building material iu differ- 

 ent ways and in different types of construction, and also beacuse it is used 

 to a large extent as a paving material, a knowledge of its physical proper- 

 ties is of value. With a view to increasing this knowledge a series of ex- 

 periments were made at Purdue TTniversity to determine the coeflacient of 

 expansion of different grades of brick. It is the purpose of this paper to 

 give the results of these experiments.* 



The method used to determine the coefficient was to subject a bar of 

 steel whose coefficient of expansion was known, and the specimen of brick, 

 to identical changes of temperature. The difference of expansion was 

 measured by the principal of the optical lever. This difference reduced to 

 unit length and unit temperature gave a correction to apply to the coef- 

 ficient of the metal bar. 



The apparatus used for these experiments was designed by Professor 

 W. D. Pence, former Professor of Civil Engineering at Purdue University, 

 and used by him to determine the coefficient of expansion of concrete. It 

 consists of, fli'st, the specimen to be tested ; second, the bar of steel of 

 known coefficient ; third, a heating apparatus, consisting of a double-walled 

 steam jacket through which the mirror of the optical lever could be seen ; 

 fourth, a rod in the opposite side of the room, whose image, reflected in the 

 mirror, was read by means of an engineer's level. The thermometer is 

 hung inside the heater and is read through the glass door by the aid of an 

 incandescent lamp svispendod alongside of it. The lamp is tui'ned on only 

 for an instant in order not to affect the reading of the thermometer. Both 

 the level and the steam jacket were mounted upon a concrete foundation. 

 The arrangement of the apparatus and the method of conducting the ex- 

 periment will be easily understood from the figure. 



''The experiments were conducted, under the writer's direction, by W. J. Burton and 

 C. W. Wilson (1902-1903), and by G. W. Case and U. C. Curtiss (1904-1905), as thesis work in 

 the School of Civil Engineering, Purdue University. 



