IX, A, 2 Reihling and Retjes: Portland Cement Materials 139 

 Table VIII. — Composition and setting properties of cement 2b — Continued. 



Material. 



Composition of clinker (calculated): 



Silica (Si02) 



Alumina (AI2O3) - 



Ferric oxide (FeaOs) 



Calcium oxide (CaO) __ 



Magnesium oxide (MgO) 



Hydraulic index 



Fineness of the cement: 



Per cent residue on the 100-mesh sieve 

 Per cent residue on the 200-mesh sieve 



Soundness, 5-hour steam test 



Per cent. 



22.54 

 3.53 

 3.06 



66.20 

 1.28 

 2.31 



93.6 



78.2 



sound 



SETTING PROPERTIES. 



Cement. 



Plaster 

 added. 



Water 

 required 

 for nor- 

 mal con- 

 sistency. 



Initial 



set. 



Final set, 



Nonseasoned (sp. gr. = 3.14) 



Do--- 



Aerated for 19 hours (sp. gr. = 3. 11) 



Do 



Do 



Per cent. 

 1 

 2 

 1 



1.5 

 2 



Per cent. 

 21 

 21 

 21 

 21 

 21 



Hrs. min. 

 15 

 2 



40 



3 



00 



35 



Hrs. min 

 4 00 

 4 50 

 5 



4 50 

 6 



As the setting properties of this higher limed cement proved 

 entirely satisfactory and easy to control, the results obtained with 

 mixtures 2, 2a, and 2b showed that it is necessary to keep the 

 hydraulic modulus within the upper rather than the lower limits 

 if quick-setting products are to be avoided. The combined re- 

 sults also show that the range of permissible variations in the 

 upper limits is sufficiently wide to permit satisfactory factory 

 control in composition. 



FINENESS 



In Tables III and VII it is recorded that with the exception of 

 5 the cements were not pulverized nearly as fine as modern grind- 

 ing machinery has made practicable. The finest ground commer- 

 cial cements which have come under our observation show about 

 the same residue on the 100- and 200-mesh sieves as No. 5 — 

 namely, 2 and 13 per cent, respectively — and our work on the 

 physical and chemical properties of Portland cement proved very 



