CEMENT-—RETARDED SETS.
506
Norton, Natural Cement.
RETARDED SET SERIES.
Samples taken out at 2-hour intervals. Main batch of cement allowed to rest undisturbed in the mixing bed between the times of taking out samples, or when regauging. Age when tested, 34 days.
Original quantities:	Pounds.
Cement.......................................................... «8•;»
Water................................................... 42.9 per cent=29.5
Water added to the main batch as follows:
Interval after mixing, hours.	Water used.	
	Pounds.	Per cent, approximate.
	29.5 2.5 1.0 • 0.25	42.9 46.1 48.7 50.1
		
		
		
Hours.	Dimensions.			Sectional area.	First crack.	Compressive strength.		Remarks.
	Height.	Compressed surface.				Total.	Per square inch.	
		Inches.	Inches.	So. inches.	Pounds.	Pounds.	Pounds.	
0	6.01	6.03	6.15	37.08	25,200	25,200	680	
0	6.05	6.01	6.14	36.90	27,550	27,550	747	
2	6.00	6.03	6.07	36.60	16,200	16,200	443	
4	5.98	5.95	5.90	35.10	10,100	11,200	319	Voids.
4	5.98	5.96	5.00	35.76	11,900	12,900	361	
6	5.93	5.00	5.86	35.16	11,700	14,900	424	
8	5.99	5.92	5.90	34.92	6,700	13,200	378	
Star Portland Cement.
RETARDED SET SERIES.
Samples taken out at intervals, as indicated in the tables which follow. Main batches of cement kept in a state of agitation in the mixing bed until put into molds.
Two kinds of cement were used of the above brand, one the ordinary commercial mixture containing plaster, the usual “restrainer,” to control the rate of setting; the other kind the same as the first, but without the use of plaster. Age when tested, 30 days from the time of mixing.
The cement with plaster was mixed when 40 days old, that without plaster when 45 days old, from the time of grinding.
Pounds -
............ 375
32.9 per cent= 123.5
............ 375.75
, 42 per cent= 158
Original quantities:
Cement, with plaster ...
Water.................
Cement, without plaster Water.................