188 



ANNALS NEW YORK ACADEMY OF SCIENCES 



Table 2 

 Effect of Cold Storage on Strength 







Temper- 





Strength 



, pounds 



Per cent of loss 





Cement 



Mix 



ature of 

 storage 

 water, 



Storage 

 method 



per square incn 







Number of 

 specimens 















deg. P. 





7 days 



28 days 



7 days 



28 days 





X 



Neat 



60 



Normal 



735 



739 











10-12 







43 



1 



606 



693 



18 



6 



12-12 







42 



2 



654 



735 



11 







12-12 







60 



Normal 



702 



745 











24-24 







34 



3 



638 



665 



9 



11 



24-23 



X 



1:3 



60 



Normal 



300 



361 











11-12 







43 



1 



281 



361 



6 







11-11 







42 



2 



283 



371 



6 



+3 



11-11 







60 



Normal 



313 



408 











24-24 







34 



3 



262 



312 



16 



24 



22-24 



Y 



Neat 



60 



Normal 



628 



843 











12-12 







43 



1 



650 



770 



+3 



9 



12-12 







44 



2 



649 



872 



+3 



+4 



12-12 







60 



Normal. 



628 



697 











24-24 







34 



3 



530 



622 



16 



11 



22-24 



Y 



1:3 



60 



Normal 



250 



350 











12-12 







43 



1 



253 



370 



+1 



+6 



12-11 







44 



2 



287 



327 



+15 



+7 



12-12 







60 



N ormal 



228 



317 











22-24 







34 



3 



197 



234 



14 



26 



22-24 



From these results, it is safe to conclude that, aside from the effects of 

 frost, low temperatures are adverse to the development of the hardening 

 process in cement, and that in general this effect is more pronounced in 

 mortars than in neat cement. 



The adsorption of calcium hydroxide by the complex hyclrogel may 

 proceed at a lower rate at lower temperatures; or if this is not so, the 

 primary hydration, of which this hydrogel is the product, may proceed 

 more slowly, and thus less of the hydrogel be produced, — either of which 

 processes will detract from the hydraulic activities of the mass. It would 

 seem from the experiments that the latter is the more satisfactory expla- 

 nation, since the test specimens which were chilled at first and allowed 

 to return to normal temperature show a tendency to return to normal 

 strength at the longer periods, while the general tendency in the series 

 kept constantly in cold water is to fall further off from the normal, indi- 

 cating only a limited available amount of hyclrogel to undergo the coagu- 

 lating process. 



