EXPANSION AND CONTRACTION OF CONCRETE. 



bring it to constant temperature as determined by a thermometer 

 likewise hung beside the specimen. A thermometer was inserted 

 also in a horizontal orifice in the middle of 

 the concrete specimen, and the tempera- 

 ture was noted at each reading. Finally, 

 all readings were corrected to eliminate 

 the effect of differences in temperature, 

 whether due to chemical activity of the 

 cement in hardening or to external 

 changes. In figure 2 is shown a specimen 

 with measuring instrument attached. 



RESULTS OF EXPANSION AND CONTRAC- 

 TION MEASUREMENTS. 



The results of these laboratory measure- 

 ments are best seen by reference to the 

 following curves : 



AGE IN DAVS 



00001 

 OOOO? 

 00003 



0004 

 00009 

 0.000b 



r 



O0-0007 



p 



O 



<£0-0008 



a 



t- 



Z 00009 



o 

 v 



. 0.0010 

 I- 



z 



30-0011 

 00012- 

 00013 

 0-00 14- 



00015 



0.0015. 



o\ 



V o 



. —^-3== 



*" o 



; a 



Fig. 2. — Specimen and appa- 

 ratus for measuring the ex- 

 pansion and contraction of 

 concrete. 



NEAT CEMENT, STORED IN AIR. 



On figure 3 is shown a typi- 

 cal shrinkage curve of neat 

 cement stored in the warm, 

 dry air of the laboratory. It 

 will be seen that shrinkage 

 takes place immediately, and at the age of 6 months a total shrinkage of 0.155 

 per cent, or If inches, in 100 feet took place. This is much less than the results 

 of White, who observed a shrinkage of 0.236 per cent, or 2J inches, in 100 feet. 



Fig. 3. — Neat cement, stored in air. 



