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tested at each of the ages.

Results. Ultimate compressive strengths, lbs/D". Each max or min
is the mean of five or more tests, upon cubes made from one of the four
brands of cem, and thus refers to the cem giving max or min strgth under
the stated conditions. The avs are those of such results for the 4 brands.



Age 1:2:4 1:3:6

max av min max av min

7ds 2219 1525 904 1550 1232 892

1 mo 2642 2440 2269 2174 2063 1816

3 mos 3123 2944 2608 2538 2432 2349

6 mos 4411 3904 3612 3170 2969 2750



1 : 6 : 12
max av min
759 583 417
1218 1042 873
1257 1066 844
1583 1313 815



For formulas, deduced from these results by E. Tbaclier, see

1f35, p 1106.



19. W. A. Rogers, Chic, Mil and St P Ry, Westn Soc Engrs, Jour, 1899.
Jun, Vol 4, No. 3, p 262, R R Gaz, '00, June 15, p 402, July 27, p 514.

19 a. Effect of cold, and of mixing with salt water. Specimens ;
comp strength of 12-inch cubes of Port and nat cem cone. 8 cubea

76



1148



CONCRETE.



For Directory to Experiments, see pp 1135-9,

Atlas Port, 1 cem, 3 gravel (2 sand, 1 pebbles), 4 hard crusher run lime-
stone; 8 cubes Louisv nat, 1 cem, 2 gravel, 3 stone.

Same as used in track elevation masonry by Chic, Mil and St P Ry.

Treatment. All the cubes made by same person in molds of 1"
lumber, and left in molds until broken.

Results.



Portland



Natural





Temp, F


Ibs/sq in.


Temp, F


Ibs/sq in


1 cube in warm office 28 days
1 " " " " 28 '


80 to 18


>1290f
>1290f


85 to 40


300

defective


1 " outdoors* 28 '


57 to 24


902J


57 to 10


200


1 " " 28 '


"


690J




256


1 " " 28 '










in office 28


85 to 32


>1290f


85 to 40


376


1 " outdoors* 28


57 to 24




57 to 10




in office 28 '


85 to 32


>1290f


85 to 40


352


1 " outdoors * ** 28


57 to 24


>1290f


57 to 10


237


1 " 28 "




>1290f




247



19 b. Character of aggregate ; comp strength.

Specimens. 12" cubes of Port cem, gravel and stone. Gravel, 2/3
coarse, sharp sand, 1/3 pebbles from sand to 1 }/%' . Each result the average
of 3 cubes. Age 28 days.



Results.

1 : 3 : 4.5
* 1 : 3 : 4.5

1 : 3 : 4.5

1:4:7

3.5 f
3.51



1 :4



Ibs/sq in

hard crusher-run limestone 1270

soft screened " 1170

washed gravel ^ to 2 in 1050

soft screened limestone 714

washed gravel % to 2 in } 642



19 c. IMrt in sand and aggregate ; comp strength.
Specimens. "Dirty" sand and gravel contained apparently abt 10%
dirt "which had the appearance of containing a large amount of iron."



Results. With sand, tensile,

90 days, Ibs/Q"
1:1 1:2 1:3

Clean 457 492 349

Dirty 627 541 430



Dirtier 515



514



396



With gravel, comp, 12" cubes,

28 days, lbs/D"

1:2:5 1 : 2.5 : 5

1097 838

988 928

1020



20



20. Edwin Thacher, E N, '99, Sep 21.

20 a. "Several brands of Port cem were improved, in tensile strength,
by a delay of from 1 to 4 hrs betw mixing and laying." Ransome.

21

21. eo. W. Rafter, A S C E, Trans, Dec '99, Vol 42, p 104.

21 a. Volume; consistency, richness and proportion of mortar.
Specimens: 544 12" cubes, broken on the U. S. Govt testing machine

at Watertown, Mass. Port cem; sand, 86.5 to 93.5 Ibs/cu ft; agg, broken
stone. Cubes abt 2 years old.

"Dry," only a little more moist than damp earth;

"Plastic," ordinary consistency used by masons;

"Excess," under moderate ramming the cone quaked like liver.

* During the first part of the 28 days, temp fell to 10 and 20 F ;
afterward, thawing during day, freezing at night.

t Flaked slightly. Strgths exceeded capacity (185,000 Ibs) of machine

j Cold believed to have retarded setting.

** Mixed with salt water, 1 pint salt to 10 qts water.



EXPERIMENT AND PRACTICE.



1149



For abbreviations, symbols and references, see p 947 1.

S = vol of sand in mortar to 1 vol cem;
M = " " mortar " cone " 1 '
A = " " agg " ". " 1 '
C = ' " cone made with 1 '
Results.



Volume



1


Mortar = 33 % agg


Mortar = 40 % agg


Proportions


Shrkg


Proportions


Shrkg


cS


S


M


A


C


t


S


M


A


C


t


D.


1


1.57


4.74


4.30


9.3


1


1.64


4.10


3.82


6.8


P.


1


1.83


5.51


5.01


9.1


1


1.66


4.14


3.82


7.7


E.


1


1.70


5.11


4.64


9.2


1


1.70


4.24


3.97


6.4


D.


2


2.42


7.29


6.74


7.4


2


2.44


6.12


5.89


3.8


P.


2


2.45


7.28


6.62


9.1


2


2.50


6.28


5.83


7.2


E.


2


2.35


7.02


6.36


9.4


2


2.60


6.47


5.97


7.7


D.


3


3.15


9.49


8.78


7.5


3


3.21


8.03


7.36


8.4


P.


3


3.30


9.92


8.89


10.4


3


3.31


8.23


7.62


7.4


E.


3


3.25


9.72


8.83


92


3


3.43


8.57


7.90


7.8


D.


4


4.18


12.69


11.75


7.4


4


4.24


10.71


9.84


8.1


P.


4


4.28


12.94


11.66


9.0


4


4.35


10.96


10.09


7.9


E.


4


4.37


13.14


11.78


10.4


4


4.33


10.84


9.64


U.I


D.


5


5.04


15.05


14.29


5.1


5


4.42


11.25






P.


5


5.00


15.00


13.66


9.1


5


5.00


12.50


lV.56


7.5


E.


5


5.08


15.20


13.6.0


10.5


5


5.24


12.90







21 b. Density of concrete : thoro ramming,

Vol of 1 : 1 mortar, Vol of rammed cone, approx,
0.33 X vol of agg, 0.91 X vol of agg,

0.40 X ' 0.93 X '

21 c. Density of aggregate ; compacting. Portage stone,
broken to pass a 2" ring, and having 43.3 % voids when slightly shaken in
the measure, had 9nly 37.4 % voids, as a mean of 5 trials, after being packed
in the measure with a tamping iron, used about as forcibly as in ordinary
ramming of cone.

22

22. Tests of Metals, '00, pp 1109, &c. For Contractors Plant Co.

22 a. Specimens; Port cem, sand, crushed stone, 1:3:5. Stone
passed thru a 2 ^" ring; pieces passing a W ring screened out.

A, Siami-mixi : B and C mix I in a portable gravity
mixer 8 ft long, consisting of a steel trough containing numerous rows of
steel pins, staggered. Water from a spray pipe strikes the mixer about
midway its length. Hence cone is mixt dry in the upper half, and wet in
the lower.

Stone spread evenly on a platform in front of mixer
Sand ' top of stone

Cem " sand.

Material then shoveled into mixer.

B. Allowed to form a cone-shaped pile, stones accumulating around



C. Material, as discharged , levelled off with hoe.
12" cubes; beams from 4" X 6" to 6" X 6" 30" span,
mos in water, 1 mo in air.



All, 2 days in air, 2



* Consistency : D = dry ; P = plastic ; E = excess.

100 (A C)
t Shrinkage = ^r '-



1150 CONCRETE.

For Directory to Experiments, see pp 1135-9,

Results ; Cubes Beams

Comp strength, Ibs/Q" Rupture modulus, Ibs/Q*

max av min max av min

A 3516 3187 2930 454 414 367

B 4451 4256 4041 564 525 450

C 4380 4123 4019 536 451 348

23

23. W. H. Henby, Jour Assoc Eng Socs, Sept 1900, p 153.

23 a. Cinder Concrete loses from M to % of its strength by being
thoroly wet; but fully regains its strgth upon being dried.

24

24. E. Duryea, Jr, "Cement," Vol 2, '01 See E. Thacher, in A S
C E, Trans, '05, Vol 54, Part E, p 447.

24 a. Finish.

Tunnel portals, Los Angeles, Cal., two coats, 1 cem : 4 sand : 1 lime paste.
Showed hair cracks where finished smooth.

Pedestals, Chicago & E 111 RR, 1 cem : 1 sand. In good condition.

Piers, Arkansas River bridge, Kan City So R R., two coats, 1 cem : 3 sand,
one coat, 1 cem : 1 sand. In good condition.

1 cem : 3 sand : 1 lime paste, considered best. Excessive troweling
should be avoided. Finish should be kept damp for two weeks.

25

25. Thayer School expts, '02. J. B. Mclntyre and A. L. True.

25 a. Permeability. 97 expts, specimens 10" diam, 9" high, %*



pipe inserted 4". Pressures, 20, 40 and 80 Ibs/D" (46, 92 and 185 ft heads),
2 hours. All specimens with from 30 to 45 % 1:1 mortar were imper-
meable. Some with 40 to 45 % of 1 : 2, and some with 1:2:4 and 1 : 2.5 : 4,
were impermeable under 80 Ibs. 1 : 2 : 4 or 1 : 2.5 : 4 recommended for
moderate pressures.

26

26. Kreuille. "Experiences sur le Ciment Armey Ann des Fonts et
Chaussees, '02, p 181.

26 a. Corrosion and adhesion in water.

Specimens; 4 slabs 36" X 39," 11.8" thick; respectively 1320, 1320,
1760, 2200 Ibs Port cem, 11.6 cu ft sand, 31.8 cu ft pebbles, H" to 1" diam.
Rods 3 A&" diam, placed at diff dists from the surfs of the slabs.

Treatment; slabs placed in water under heads of 40 to 50 ft (17 to
22 Ibs/D") which were transmitted undiminished to the centers of the
blocks. Pressures relieved from time to time. Treatment maintained for
several days. Slabs then left in air, exposed to weather.

Results. The metal was found perfectly preserved; but its surf, which
was bright when placed, was found dull when exposed after the expt, and
adhesion was destroyed where the water had circulated.

26 b. Ijuster. Bars, with bright surf, placed in cem mortar for several
days, showed dull surf after removal of the mortar, indicating chemical action
betw the cem and the iron. It is probably by such action that rust is re-
moved from rusted bars, placed in cem mortar. The iron salt, formed by
this action, is dissolved by the water which penetrates to the iron surface.

26 c. Gain and loss of weight. Small pieces of sheet iron,
placed in cem mortar, gained about 0.01 % in wt in 76 days. Subsequently
placed in running water, such plates lost wt, indicating the solubility of the
compound, the formation of which had increased the wt.

26 d. Time; adhesion. Iron plates, 35 X 70 X 5 mm (1% X
2 H X 0.2 ins) were laid upon freshly laid cone, in which the mortar (500
kg Port cem to 1 cu meter sand) flushed to the surf. At diff periods, these
plates showed av adhesion as follows:

27 12 17 23 27 days
0.278 0.636 0.946 1.132 1.295 1.316 kg/sq cm
3.96 9.01 13.5 16.1 18.4 18.7 Ibs /sq inch

The results of Expt 26 d were not materially modified when the mortar
was kept in the sun, or mixt warm or very wet.



EXPERIMENT AND PRACTICE. 1151

For abbreviations, symbols and references, see p 947 1.

27

27. G. Y. Skeels, Asst City Engr, Sioux City, Iowa. E N, '02, Nov 6,
p382.

27 a. Avs of 2 and 4 briquets, 1 day in air, 14 ds in water. Port cem.
Under continuous mixing for 8 or 10 hrs, neat cem mortar lost about

% of its tensile strength. ; 1 : 2 lost about %.

28

28. Thos. S. Clark, Resident Engr in Chg of Construction of Man-
hattan R R Power Station, New York. E N, '02, Jul 24, p 68.

28 a. Retempering; strength. Neat nat cem mortar mixed
initially with 28 % water; sand nat cem mortar with 14 %. Retempered
an hour after mixing, "enough water being added, as in practice, to bring
the mass back to its original consistency." One day specimens 3 hours
in air, the others 24 hours. Retempered specimens showed, in general,
about half the normal strgth.

Similar results were obtained when the cem was moistened every 15
mins during the hour. In such cases, in practice, the strgth is sometimes
increased by adding a little fresh cem.

Port cem mortars, retempered after standing an hour, failed to show
marked deterioration, probably because Port cem sets more slowly than
nat cem.

29

29. W. Purves Taylor, A S T M, Vol 3, p 376, '03.

29 a. Age ; soundness. Ageing of finely ground cem permits hydra-
tion of the free lime, nearly always present, rendenng it inert and preventing
expansive action. Specimens, made with cem one wk old, were unsound;
but, as the age of the cem increased, the soundness of the specimens improved
until, when the cem was 5 wks old, the specimens were sound.

29 b. Fineness; soundness. The larger particles of coarsely ground
cem are not readily hydrated. A cem, of which 33 % remained on a No 200
sieve and 13 % on No 100, checked and cracked in the boiling test; but
became sound when reground until all passed the No 100 sieve and allowed
to season for 2 weeks.

30

30. French Government Commission, Beton und Eisen, '03,

30 a. Ductility. Cone 1:2:4. Results similar to Considered
(see Expt 16 a). Ductility greater when hardened in water than when
hardened in air.

31

31. Chas. List, Assn Eng Socs, Jour, Mar, '03, Vol 30, No. 3, p 128.

31 a. Effect of sea water at Gautemala, Central America.

Hollow piles, in sea water, filled with cone in which sea water had been
used for mixing. Some of the mortar leaked out, and formed, with the
surrounding sand, masses of cone which adhered to the piles. When piles
were removed, cone was found perfectly hard and adhering tenaciously to
the piles.

31 b. Railway bridge foundation, built 1895. Lean cone mixt with
and standing in brackish water. Of excellent quality in '03.

31 c. Regrinding. Cem brought from Hamburg, Germany, in bbls.
Vessel sprang a leak; cem considered a loss, and value refunded. Cem
stored under the floor of a warehouse with open sides and exposed to mois-
ture of ground and to spray from sea. Cem caked hard enough to be used
as foundations for wooden posts in buildings. This caked cem was broken
as fine as possible, and mixt with sharp beach sand and brackish water.
Cone perfectly hard in 3 days and used in bridge foundations in brackish
water.

32

32. Oeo. W. tee, Jr., E N, '03, Mar 19, p 246.

32 a. New York Central R R. Forms (2" tongued and grooved pine)
coated with soft soap ; openings in joints filled with hard soap. Cone
deposited and drawn back from mold with a square-pointed shovel, and 1 : 2



1152



CONCRETE.



For Directory to Experiments, see pp 1135-9.

mortar poured in along the molds. After removal of molds,' and while
cone green, surf rubbed, with a circular motion, with pieces of white fire-
brick, or bricks, of 1 cem : 1 sand; surface then dampened and painted
with 1 : 1 grout, rubbed in and finished with wooden float.

33

33. Wm. B. Fuller, A S C E, Trans, '03, Jun, Vol 50, p 454.

33 a. Reinforced Concrete tank at filter plant, Little Falls, N. J.
10 ft diam, 43 ft high; walls 15" thick at bottom, 10" at top; built in 8
hours; all cone placed from top, thus falling 43 ft at first. Mixt very wet;
placed 5 cu ft (wheel-barrow-load) at a time, and merely joggled into posi-
tion. Tight against both inflow and outflow; intended inside plastering
omitted as unnecessary. Surfs smooth, no stones or voids showing.

34

34. Prof. C. E. Sherman, E N, '03, Nov 19, p 443.

34 a. Clay and loam ; Strength.

Dyckerhoff (German) and Lehigh (American) Port cems, with sands
containing from to 15 % of clay and loam. Strgth in general in-
creased materially with the percentage of clay and loam. Wi*h 10 and 15
%, the strgth, at 12 mos, was from 15 to 50 % greater than with clean sand.

35

35. Tests of Metals, '04, pp 345-387.

35 a. Concrete columns, plain and reinforced ; ultimate
comp strength, s, Ibs/sq inch and elastic modulus, E,* Ibs/sq inch.

Specimens. Port cem and sand; agg, pebbles and broken trap, % to
1 W and cinders. Cols approx 12%" X 12 W X 8 ft. Reinforcing rods;
"Tw," %" twisted; "Cr," 5/8" corrugated; "Th," %" Thacher.



Results.






Ae-p


Reinforcement






K


Age

* N


No. &








No. Mix Agg


Waterf


mos days


Kind


% t


s


0.001 E*


1 1:1:2 Pebbles


42.5


8





4Tw


1.46


2890


2660


2




7


28


None


None


1720


2500


3 1:2:3






7


28


4Tw


1.44


2010


2273


4




53.1


7


25


None


None


1769


2155


5 1:2:4




56.7


3


13


4Tw


1.43


1990


1938


6






3


16


4Cr


0.97


2180


2212


7









3


14


4Th


1.03


1990


2315


8






"


3


15


8Tw


2.86


3160


2500


9 *









3


14


8Cr


1.94


2830


3049


10






"


3


12


8Th


2.09


2760


3086


11






<


7


26


4Tw


1.45


1820


2381


12






"


3


17


None


None


1710


2358


13
14


Trap
Cinder


"wet"


5
5


10
16


None
4Tw


None
1.45


1750
2095


2809
1404


15




"


5


16


None


None


871


1000


16 1:2


: 6 Pebbles


74.4


7


24


4Tw


1.44


1370


1036


17






7


23


None


None


462


1442


18


Trap




5


10


8Cr


1.94


2290


3086


19




57.6





7


None


None


471


2208








36 -










36. F. E. Turneaure, A


S T M, Trans, '04,


p 504.






36 a. Ductility.


Reinfd


cone beams. Unit

j. _ f\ f\f\f\r> r- J _ ,


stretch


of cone, on first



, . .,

cracks, appearing when stress in steel > 5000 Ibs/Q". Plain beams rup-
tured (without preliminary cracking) with equal unit elongation. The

*E taken betw limits of comp stress as follows, lbs/D": Nos 15 and 17,
100 to 600; 16, 600 to 1000; 19, 100 to 471; all others, 1000 to 1500.
t% of cem by wt \% of cross sec area



EXPERIMENT AND PRACTICE.



1153



For abbreviations, symbols and references, see p 9472.

cracks, corresponding to the lowest unit stretches, were invisible on dry
cone, but were detected, in moist cone, by the appearance of narrow wet
streaks about %" wide. A little later, they showed as dark, hair-like cracks.

37

37. Prof Bauschinger, "Beton und Eisen," '04, Vol IV, p 193.
37 a. Corrosion ; adhesion.

Fragments of reinfd cone plates, broken, in testing, '87; exposed
outdoors until examined in '92. Adhesion; cone broken off by hammer
blows, breaking only in immediate vicinity of blows. Corrosion; steel
rust-free, even close to the exposed surfs of fracture.

37 b. Tank, injured by rough treatment; cracked; reinfmt laid
bare in places. Rust only where so exposed. Adhesion as in 37 (a).

37 c. Fragments of Monier plates 6 to 8 cm thick. Exposed, at inter-
vals for about 4 yrs, to sewage-polluted water. Cone remained hard;
reinfmt ruat-free 1 cm from exposed surface ; adhesion excellent.

38

38. A. Kleinlogel, Beton und Eisen, '04, Vol 2.

38 a. Ductility. Reinfd cone beams 15 X 30 cm, 220 cm long.
1:1:2, cem, sand, limestone screenings. Kept under moist sand 6 mos.
Bendg mom constant thruout measd portion. Unit stretches in cone;
reinfd, 0.000148 to 0.000196; plain, 0.000143.

39

39. Clarence Coleman ; Report, Chf of Engrs, USA, '04. Part IV.
Universal Port cem made from blast furnace slag.

Av tensile strgth, Ibs/Q"



Sand* Mix
39 a.

Cem in good condition Q 1:3

Cem exposed in sacks to damp-
ness Q 1:3

Caked hard. Not set. Reground Q 1 :3
39 b.



Water** 7

da



Cem as received on works

Cem after 4 to 10 mos in sacks in



warehouse.

39 c.



Cone hand-mixt on platform!

Cone mixt in cubical batch-
mixer J

39 d.

As in laborat'y, 24 hours in
damp closet, then immersed
until broken If

As on work, 10 days under
damp cloth, then in air until

brokenlf

39 e.

8.25 % water**

9.25 % water **

39 f.

Pebbles Vie to % inch

Pebbles % to % inch

39 g.

Clean sand ...



Stt

Sand with small % clay [STT



1:10 Random
1:10 Random



12.5



12.5
12.5



12.5
12.5



1 :10 Random 262



176

173
199

1.00 1
1.17 t
134
253



1:10 Random



8.25



1:10 Random
1:10 Random



222

254



8.25
8.25



164
184



183
183



28
da
298

260
274

1.00 t
1.09 t
211
274



366



388



289
317



275
314



259
272



mo yr yr
424



420



462 394



643 834

399
437

445

4t>4

340



* Q = Standard crystal quartz.

S = Superior Entry sand; passing sieve No. 4 10 20 30 50

% 100 72.3 46.1 26.5 5.1

t Relative strgths. t Briquets made of cone taken from the works,

g A batch of very perfectly mixt cone in 80 sees.

\ Cone taken from mixing platform Stones larger than %" removed.
** In order to approx working conditions, the mortar was allowed to stand
30 mins longer than under ordinary treatment.

tfPassing No 10 sieve. %% Water in percentage of dry agg.

C9



1154 CONCRETE.

For Directory to Experiments, see pp 1135-9.

4O

40. Prof < lias. L,. Norton. E N, '02, Oct 23, '04, Jan 14.
Corrosion. Several hundred briquets of various mixes and consist-
encies, with steel imbedded, subjected to air, steam and carbonic acid.

4O a. Steel clean when imbedded. 3 wks exposure.
Steel perfectly protected by neat cem in all cases, and where the mortar
was mixt wet, so as to cover the steel with thin grout.

In cone, rust found only where voids or other defects existed.

40 I>. Steel rusted when imbedded. 1 to 3 mos exposure.
Changes, in size of steel, occurred only where cone had been poorly applied.

41

41. John S. Sewell, on Baltimore fire, E N, '04, Mar 24.

41 a. Results. "Concrete undergoes more or less molecular

change in fire; subject to some spalling. Molecular change very slow.
Calcined material does not spall off badly except at exposed square corners.
Efficiency, on the whole, is high. Preferable to commercial hollow tiles
for both floor arches or slabs, and col and girder coverings."

41 b. Reinfd cone cols, beams, girders, and floor slabs, at least as de-
sirable as steel work protected with the best commercial hollow tiles.

41 c. " Stone cone spalls worse than any other kind, because the pieces
of stone contain air and moisture cavities, and the contents of these rup-
ture the stone, when hot. Gravel is stone that has had most of these
cavities eliminated by splitting through them, during long ages of exposure
to the weather. It is therefore better than stone for fire-resisting cone."

41 d. " Broken bricks, broken slag, ashes and clinker all
make good fire-resisting cone."

41 e. ** Cinders, containing much partly burned coal, are unsafe, be-
cause these particles actually burn out and weaken the cone. Locomotive
cinders kill the cem, besides being combustible. Cinder concrete is safe
only when subjected to the most rigid and intelligent supervision; when
made properly, of proper materials, however, it is doubtful whether even
brickwork is much superior to it in fire-resisting qualities, and nothing is
superior to it in lightness, other things being equal."

42

42. Emile tow, A S C E, Trans, June '04, Vol 52, p. 96. Buffalo
Breakwater.

42 a. Shrinkage.

Cement 258 cu yds

Sand 365

Pebbles 1175

Broken Stone 972

Total Materials. . . . .2770
Blocks made 2054

Shrinkage 716 " = 25.8 %

43

43. Alex. B. Moiicrieff, Engr in Chief, South Australian Govt
Letter to authors, June 7, '04.

43 a. Permeability.

Specimens. Cone blocks, 2 ft cubes (8 cu ft), for expts in connection
with construction of Barossa dam. Ingredients same as used on dam.
Agg %" to 2", with varying voids. Preparation of aggs very carefully
watched.

Treatment. Water brought to cen of block in }/%' wrought iron pipe
terminating in a T piece, wrapped with hemp which formed a bulb abt
4" diam.

Results. All the blocks became practically tight. Cone
used in dam "was based upon the results of the expts principally with blocks



EXPERIMENT AND PRACTICE. 1155

For abbreviations, symbols and references, see p 947 1.

Nos 7 and 8." There is "practically nothing that could be called a leak"

thru the dam.*

Q = vol of mixing water, % of volume of cone;

_ _ vol of mortar vol of voids
X = excess mortar = 100 - vo l of voids ~ ''

A = age of block, in weeks, when subjected to pres;

/ = interval in mins, betw application of pres and appearance of water
on surf of block;



Head = 100 ft
closely resembled


= 43.4 Ibs/Q." Under 200 ft (86.8 Ibs/D") "the effect
the results obtained from the head of 100 ft."
Observed Leakage*








Q


X


A


7


Mean rate


No.


Cem. Sand


Agg


%


% Weeks


Mins


Pints


U. S gals /mo-


1


1 1.84


5.26


16.65


5


11


t


t






t


2


1 1.84


5.26


15.45


5


11


34


% in


7 wks.


0.065


3


1 1.50


4.63


16.04


5


10


18


Mo "


4


"


0.005


4


1 2.00


4.50


16.04


15


10


14


14 "


2


"


4.000


5


1 1.75


4.13


16.65


15


9


12


27 "


7


"


2.353


6


1 1.50


4.12


16.04


10


8


35


Vo "


2


"


0.006


7


1 1.50


3.90


14.26


12.5


6


28


y "


2


"


0.037


8


1 1.50


3.70


13.68


15


5


30


Ho "


1


'


0.006



44

44. Edwin Tliacher, A S C E, Trans, '05, Vol 54, pp 425, &c.

44 a. Effect of cold. Melan arch bridge, at Mishawaka, Ind,
3 spans, 110 ft each, built in temps ranging from to 55 F. Hot water
admitted to mixer. Cone laid at blood heat; warm enough to melt snow
48 hours later. Center arch completed with temp about 25 F. The next
day, temp fell to F. Two wks later, an ice jam carried out the centering
and left the arch unsupported. No bad effects observed; settlement
but little greater than with the other arches, centering under which was


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