176 
REIBLING AND REYES. 
practise is therefore self-evident. 
ard specifications permit the manufacture and use of Portland 
cements which may contain aS much as 25 per cent of inert 
materials, the pulverization of which would add about 20 per 
cent to the efficiency of the product at an additional cost of 
less than 5 cents per barrel. 
However, our present stand- 
TABLE LIV.—Physical properties of cement L before and after regrinding. 
| Fineness. Time of setting. 
AH ———— a SORE 
aes Specific} 
Condition. A (5-hour 
Ex avatye arece preven Initial Final |steam test). 
200 sieve.|100 sieve.| Se Bers 
Per ct. | Per ct. |Hrs.Min.\Hrs. Min. 
VAs\receiv.ed eee ae sae ne nema nee 38.110 81.2 97.3 2 20/ 5 O | Sound. 
Regroundss24225 2255. ee 3.105 97.5 99.9 1 16] 3 0 Do. 
TABLE LV.—The effect of fineness upon the temporary and permanent 
strength of hard-burned Portland cement L. 
| Per cent of 
Age in days. Age in months. gain based on 
Ce- Description. eee 
ment. 
1G 28. 3. 6. 12, | 24 28. |7 days. | 28 days. 
L | Tensile strength of neat 
mortar in water ---| 6509 603 668 703 | 670 | 690 666 |+ 30.8 |+ 10.4 
JEPY | et do aioe oe ee 583 624 655 646 | 608 | 640 642 |+ 10.1 |+ 2.9 
L | Compressive strength of 
neat mortar in water___| 4,620 | 6,100 | 6,820} 7,980} * | XX | 11,010 |+188.3 |+ 80.5 
Te: jesek Cs ee eae ee 5, 430 | 6,480 | 9,000 | 10,600 | | X | 11,300 |4+108.0 |+ 74.4 
L | Tensile strength of 1:3 
Ottawa sand mortar 
weathered outside_____- 239 393 875 455 | 514 | 5387 763 |+219.0 |+ 94.2 
ay) | eee do eee ee st 287 425 366 444; 461 | 687 792 |+-175.7 |+ 86.4 
L | Compressive strength of 
1:3 Ottawa sand mor- 
tar weathered outside __| 2,130 | 8,180 | 2,820] 4,100} * | X | 5,260 |+147.0 |4 68.1 
Le |_---- i (a ee eee 1,920 | 2,900 | 3,840} 5,110) x | x 6,360 |+203.1 |+119.3 
L | Tensile strength of 1:3 
quartz sand mortar in 
water. 04 $5 ue Uist ate 153 201 283 280 | 288 | 265 255 |+ 66.7 |+ 26.8 
WY pees dota ess ee 190 287 350 322 | 289 | 291 303 |+ 59.5 + 5.6 
L | Compressive strength of 
1:3 quartz sand mortar 
iniwater)-<-=- ssc ceces oes 1, 645 | 2,120 | 2,160 | 2,200) X x 2,921 |4- 77.6 |+ 87.7 
x | xX 
WAN |feaseck OO) espe eeseuee races 1,590 | 2,490 | 3,120} 3,260; X | X | 8,680 |+122.0 |+ 41.7 
® Reground. 
> The value of each test represents the average of 10 determinations. 
