HZW yoi:k state UOSSUU 



WKioiiT 



X] tioo of the weight of cement to its tensile strength is 



;in ,1 work, if used alone, it is of little 



ytlx while in connection with the other tests recom- 



onnecei apt when the relative bulk of equal 



ighta of cements is desired. 



We recommend that the cubic foot be substituted for the bushel 

 adard unit, whenever it is thought best to use this test. 



SETTING 



The rapidity with which a cement sets or loses its plasticity 

 furnishes no indication of its ultimate strength. It simply shows 

 initial hydraulic activity. 



For purposes of nomenclature, the various cements may bo 

 divided arbitrarily into two classes, namely ; quick setting, or those 

 that set in less than one half hour; and slow setting, or those 

 requiring one half an hour or more to set. The cement must 

 be adapted to the work required, as no one cement is equally 

 good for all purposes. For submarine work a quick setting ce- 

 nt is often imperatively demanded, and no other will answer, 

 while for work above the water line less hydraulic activity will 

 usually be preferred. Each individual case demands special treat- 

 ment/ The slow setting natural cements should not become warm 

 Avhile setting, but the quick setting ones may, to a moderate ex- 

 tent, within the degree producing cracks. Cracks ^in Portland 

 t indicate too much carbonate of lime, and in the Yicat 

 cements too much lime in the original mixture. 



SAMTLIXO 



There is no uniformity of practice among engineers as to the 

 sampling of the cement to be tested, some testing every tenth 

 barrel, others every fifth, and others still every barrel delivered. 

 luaUy, where cement has a good reputation, and is used in large 

 1IU , icrete in heavy foundations or in the backing 



i>T hearth thick walls, the testing of every fifth barrel seems 



be sufficient; but in very important work, where the strength 

 .,f each barrel may in a great measure determine the strength of 

 that portion of the work where it is used, or in the thin walls of 



•ers, etc., every barrel should be tested, one briquet being 

 made from it. 



In sr-b-ctiii? cement for experimental purposes, take the samples 

 from the interior of the original packages, at sufficient depth to 



