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, bnt 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 
the 1 00-foot section. 
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NOV. 7 , 1914- 
MARCH 6,1913 
JUNE 15, 1915 
Q47o| 
TEB. 22.1916 
TEMP ?o A v T 6 R -5. F »^ V£:ME:NT Fig - 18.— Expansion and contraction of 
nov. 7 -54° concrete, Ohio Post Road. Section at 
mar e -.37° Mt. Sterling. Laid Nov. 5, 1914. Sec- 
JUNE 15-75° 
FEB. 22-41° 
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 1J 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- 
