Section III., 1914. [19] Trans. R.S.C. 



The Crushing Strength of Ice. 

 By H. T. Barnes, D.Sc, F.R.S. 



(Read May 27, 1914). 



The crushing strength of ice is variously quoted as being from 

 327 to 1,000 pounds per square inch, as determined by a stan- 

 dard U. S. testing machine. The importance of this value in 

 estimating the expansive force of an ice sheet makes it de- 

 sirable to have more accurate knowledge of this constant. 

 Czowski in 1871 determined it for ice below the freezing point, 

 and found it 208 pounds per square inch. Ludlow made an 

 estimate of it from a study of the ice of Delaware Bay. He concluded 

 that it varied from 100 to 1,000 pounds with an average of 575 pounds. 



C. A. Mees in a paper (not published) sent privately to me, 

 concluded that the crushing strength of ice might reach as high as 

 800 pounds in a short column. He says, however, "Wherever the 

 effects of ice expansion have been carefully observed, it has been noted 

 that bending takes place, and this may be expected because we have 

 a long column effect. On this account assuming one half the crushing 

 strength may be developed before bending, the maximum thrust may 

 equal about 400 pounds per square inch." 



Probably the best experiments on the crushing strength of ice 

 have been made by Mr. Geo. G. Bell. He worked with small cubes of 

 approximately two inches. His results are summarized in the following 

 table. See table I (Maine Society of Civil Engineers, Vol. I, 41, 

 1911). 



If we neglect his highest result, which appears to me to be too 

 high, we find values more consistent, ranging from 358 to 783 pounds. 

 The second part of the table deals with the adhesion of ice to concrete 

 blocks. The crushing force is given here somewhat less than from 

 the direct experiments. Mr. Bell states that he considers 400 pounds 

 a fair estimate of the crushing strength of ice from all his tests. 



Present Experiments. 



In order to determine the crushing strength with perfectly clear 

 ice on somewhat larger blocks, I carried out a number of measurements 

 using a hydraulic press. The blocks were cut from river ice which 

 was specially selected for me through the kindness of the City Ice 

 Co., Montreal. 



