| Show HEAT INFLUENCES CONCRETE Discovery Made That Edges Curl Up and Down in Response to Temperature Temperature Temperature Tem Tem- Changes That the edges of concrete roads reads curl up and down In response to changes In temperature Is the discovery discovery ery recently made by the bureau of ot public roads of the United States Department Department Department De De- DeI De- I of Agriculture In the course of experiments at the departments department's experimental farm at Arlington Va Curling Is caused by the unequal expansion expansion expansion ex ex- ex- ex and contraction of the up upper er erand and lower sides of the concrete slab under the Influence of heat It has been observed during the middle of the day when the surface of the road becomes hot it expands more than the cooler underside and causes the sides to move downward At night w when jen the surface Is cool the contraction ion causes es the edges to rise slightly The Thee e extreme movement mo may be as much as tenth one-tenth of an Inch While the warping of the concrete Is not In Itself detrimental to the road it may lead to failure of the surface under the tho wheels of vehicles which travel over oyer It when parts of It are not resting on the ground |
