Public works . s. A 3,500-pound load applied six inches from thecorners of the thinnest (four-inch) rigid pavementsproduces tensile fibre stresses ofi about 500 pounds persquare inch, considering the corners as unsupportedcantilevers. As the test specimens cast of the tamematerial and at the same time as the sections werelaid had showed a modulos of rupture of from 600fKJunds to 650 pounds per square inch, the actualstress produced in these sections is approximately 75to 80 per cent, of the ultimate, and therefore cornerbreaks in all such sections might be expected. This same load applied in l
Public works . s. A 3,500-pound load applied six inches from thecorners of the thinnest (four-inch) rigid pavementsproduces tensile fibre stresses ofi about 500 pounds persquare inch, considering the corners as unsupportedcantilevers. As the test specimens cast of the tamematerial and at the same time as the sections werelaid had showed a modulos of rupture of from 600fKJunds to 650 pounds per square inch, the actualstress produced in these sections is approximately 75to 80 per cent, of the ultimate, and therefore cornerbreaks in all such sections might be expected. This same load applied in like manner to five-inchrigid pavements produced tensil fibre stresses ofabout 300 pounds per square inch. After the line of traffic had been changed fromthe edge to 30 inches in on one side of the pave-ment, there were no further failures on that side, buton the opposite side—resulting from applications ofloads received after the line of traffic was changedon the one side—there were 14 corner breaks in 6 occurring before the joints were cut and 8 ^fterthe joints were cut. There is no doubt that thechange of traffic prevented further failures on thatside of the pavement. That the opening of the cracks and joints, due tocold weather, makes a marked difiference in the car-rying capacity of a given pavement is shown bj theresults obtained from this test. Only two cornerlireaks occurred during the 1,167 applications of the3,500-pound load before the joints were cut, but 7corner breaks occurred during the following 1,000applications of the same load applied after the jointshad been opened. Apparently the night loading was little if anymore serious than the day loading, possibly due to thefact that the subgrade had been crowded away fromunderneath the edge of the pavement before thenight runs were made, by the continuous applicationsof the truck loads along the edges. If this is thecondition, the stress during day loading to which theslab was subjected would be as great as d
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectmunicip, bookyear1896
