TESTS OF WISCONSIN BUILDING STONE 



54i 



TABLE VII 



ULTIMATE STRENGTH IN POUNDS PER SQUARE INCH OF FROZEN 



SAMPLES 



TABLE VIII 



COMPARATIVE CRUSHING STRENGTH OF FRESH AND FROZEN 



SAMPLES 



Crushing 



strength of 



fresh samples 



Crushing 



strength of 



frozen samples 



Difference, or 



loss in strength 



through 



freezing 



Granite and rhyolite : average difference in 

 strength of twenty-three fresh and eighteen 

 frozen samples from eleven different quarries 



Limestone : average difference in strength of 

 twenty-one fresh and twenty-one frozen sam- 

 ples from eleven different quarries 



Sandstone : average difference in strength of 

 eighteen fresh and twenty-four frozen samples 

 from ten different quarries 



29,696 



25,222 



5,46l 



22,793 

 18,267 



4,453 



6,903 

 6,955 

 1,008 



These experiments illustrate two points which I have made 

 in the previous discussion: (1) that the results of freezing and 

 thawing can be best estimated from the loss in crushing strength ; 

 (2) that the larger the pores, without respect to the percentage 

 of pore space, the less will be the injury from freezing and 

 thawing. There is little doubt but that a stone having a high 

 percentage of pore space, if completely saturated with water and 

 frozen, will suffer greater injury than one with a lower percent- 

 age. But the conditions under which freezing takes place must 

 be considered before conclusions reached are of any practical 

 value. These conditions include a time element which enters to 

 modify very materially the results. After making this time ele- 

 ment as short as the conditions under which the experiments 



