M.w TOBK MATE UU8ETJ1I 



hydraulic properties when ignited 



but hai when heated with silica, alumina and clay, 



: probably plays do part in the formation of cement It will 



place lime in mixtures, the composition of which Bhould 



be i the basis of lime only, without regard to the 



it. 

 the formula previously given they made up and tested 

 own below. 1 



Tens. str. Msq 

 in. section 



\1203 Pat. tail Hot t^<t 7 days SSdaya 



Silicate 95 8 1 ~, Bet hard, sound, Boun ,-., 



Aim: n m ' K one hard 1M Ui 



Silicate Bl.l ... . . Set hanl. sound, Sound. «.;■ ,. Q „,>- 



Alum ,1,J ~ 41 4 hard 148 ^ 



Silica ,., ,- 7 Set hard, sound, 1ft * •« 



■ i=; ft* <n in «a io Set quick. sound, Bound, on g ass. 1rt - «. 



▲luminal- IM 65 ' 31 19 ' 69 U off glass ha. 10 ° M 



The actual composition of some leading cements on the market 

 given below. 



Calcium silicates 



R.Cat.. 

 Formula BiA I Pat.- Hottest 



2 (a SiO 1.85 65.11 31.88 Pet li i: 1. h ird 7 .lavs, hard 8 weeks Sound, < nglass,hard 



30 fairl? hard 7days,hard 6 weeks 



I C rt, fairly hard days, hard 6 weeks " 



8>*CaO Siu.' 8.97 7u.£6 £i.41 Cracked soft i day, hard ti weeks » 



Dr Michaelia considers that in good Portland cement the 

 ;il Bilicates to the lime Bhould be about as one 

 to two, and that the variation from this ratio should only be 

 within narrow limits. ( \ ments rich in lime set more slowlv, but 

 harden better than those poor in lim< rich in silica 



erally r than those rich in alumina but the former 



harden very illy in the beginning and are better for 



r. According to J h Michaelis 2 the celebrated 



•land cement manufactured i S tin in Germany 



ge of nearl; .li of alumina and 



rid. 



A i aterial like the lin • of Teil is \<>r h - admirably 



sui- r the manufacture of Portland cemeiit to 1"- used in 



1897. v. ?>, no. C, p. v 

 h. Die moderne aufbereitung un<l \v*rtung der mortel materialien. 

 p - 



