PROPERTIES OF PORTLAND CEMENT. 381 



Table II. — The effects of increasing temperature on raw material (rotary kiln 

 process with limestone and clay). 



Sam- 

 ple 



num- 

 ber. 



Distance 



from the 



hot end of 



furnace 



at which 



sample 



was taken. 



Color of 

 material. 



Physical 

 condition. 



Microscopic test with phenol 

 (duplicate specimens). 





Meiers. 









7 



16.4 



Pinkish-gray 



Not sintered. As 



No crystals developed within 2 hours. 







Pink color due to 



fine as the raw 



The material contains no calcined 







the presence of 



meal . 



limestone 







free ironoxide. 







11 



10.0 



Light yellow 



Slightly sintered 



In 5 minutes the slide showed a mass 







Change in color 



and gritty. 



of radiating clusters and single short 







due to less free 



White particles 



needles. A few plumes also appeared. 







iron-oxide and 



and a few 



The material contains a considerable 







to the forma- 



small porous 



amount of calcined limestone in the 







tion of a green- 



lumps (pea 



form of free, nonsintered lime. A 







ish-brown sub- 



size). 



little free lime has sintered. 







stance. 







13 



7.5 



Light to dark 



Slightly sintered 



An almost immediate and abundant 







brown. Spot- 



into small, soft, 



formation of plumes and some clus- 







ted with white 



porous lumps. 



ters of short radiating needles ap- 







specks. 





peared. Most of the free lime has 

 become sintered. 



15 



6.2 



Brown to black. 



Brittle but por- 



An almost immediate formation of 







Spotted with 



ous and soft. 



plumes in great numbers, no radiat- 







white specks. 



Easy to grind. 

 Sintered into 

 large and small 



ing nor separate needles. All of the 

 free lime is sintered. 

















lumps. 





18 



4.6 



S t e e 1-g ray to 



Very brittle but 



Plumes in abundance but not as many 







black with 



still porous. 



as sample No. 15. The percentage 







white specks. 



Hard to grind. 

 Large and 

 small lumps. 



of free lime has decreased. 



22 



Outlet. 



Steel-gray and 



Rounded lumps. 



Fair amount of plumes. Some single 







still slightly 



Well sintered, 



clinkers gave a negative test for free 







spotted with 



denseandhard. 



lime. The material contains only a 







white specks. 



Very hard to 

 grind. 



small amount of free lime. 



