DETEEIOEATION OK Ko.\l>s. 



13 



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The table shows that the amount of water absorbed bv the bi-st rocl<s 

 for road making is small, but even where the amount is very laro-e the 

 act ion of frost does not seem to be markedly injurious. The following 

 statement has been made concerning the effects of frost on paving 

 brick: 



The last two years the city of Peoria has conducted freezing tests, which are not 

 completed, but they have gone far enough to show that the average brick could absorb 

 6 or 8 per cent and still not be affected by repeated freezing. If the absorption is 

 that high, the brick would be soft and the wearing away under traffic would he such 

 that the brick should be rejected for paving. " 



While subjecting saturated paving bricks or fragments of rock 

 to a freezing temperature may injure them but little, yet when an 

 entire road surface freezes the effect is very different, for the absorp- 

 tive power of the road is, with most materials, far greater than that 

 of the material itself, and the strength of the road as a whole is far 

 less than that of its individual components. In the case of pavements 

 which have but little yield, such as brick and stone block on concrete 

 foundations, the stresses >et up by fret-zing must be very great. 



By far the most destructive work of frost is effected on crushed 

 stone or gravel roads. If the construction is defective and the main- 

 tenance poor, water accumulates in the body of the road, which spreads 

 the material so much on freezing that the bond in sonic cases i- 

 destroyed, and in other cases much weakened. Kxperimcnts have 

 been made to determine the increase in volume of wet rock dust, simi- 

 lar to that composing the binder of macadam roa<U. when subjected 

 to the action of frost. Compressed briquettes of the <iu>t were satu- 

 rated with water and exposed to a temperature considerably below 

 the freezing point for twelve hours. They were carefully measured 



Proceedings of the Illinois Society of Engineers and Surveyors, 1897. 



