EXPANSION AND CONTRACTION OF CONCRETE. 



25 



On November 7 the second set of readings was taken at a tem- 

 perature of 54° F. A very small expansion of the concrete was indi- 

 cated, but at one of the joints a small expansion took place. This is 

 somewhat hard to explain but is of no practical consequence, since it is 

 so small. On March 6 the third set of measurements was taken when 

 the temperature was 37° F., or 14° lower than the initial temperature. 

 Note the large contraction of the concrete and the correspondingly 

 large expansion at the joints and at the single crack that formed in 

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NOV. 7 , I9I4- 



MARCH G.I9I3 



JUNE IS, 1915 



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FEB. 22, 1916 



TEMPERATURE OF PAVEMENT 

 N0V.6 -5I°F. 

 NOV. 7 - 54° 

 MAR 6 -37" 

 JUNE 15-75° 

 FEB. 22 - -41 ' 



Fig. 18. — Expansion and contraction of 

 concrete, Ohio Post Road. Section at 

 Mt. Sterling. Laid Nov. 5, 1914. Sec- 

 tion III. 



On June 15 the fourth set of readings was taken at a temperature 

 of 75° or 24° warmer than when the initial readings were made. 

 Again it will be noticed that the uncracked portions of the concrete 

 have expanded with the higher temperature. A second crack had 

 formed during the previous winter, and it, together with the first 

 formed crack, showed expansion or widening. Note the enormous 

 contraction of one of the expansion joints, a contraction of 0.472 or 

 almost one-half inch. One side of this joint overrode the other, so 

 that it projected above the surface of the road about H inches. The 

 last set of readings was taken on February 22, when the temperature 

 was 10° F. below the initial temperature of the road. Enormous 

 expansions are seen to have occurred at the cracks and smaller expan- 



