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removed later and in the usual way.

44 b. Finish.

Bridge at Aconomowoc, Wis. Mortar face, 1 cem : 1 granite screenings
: 1 torpedo sand. On the second day after completion, molds removed and
surf rubbed with a soft stone and water.

Inman arch, Hohenzollern. 1 cem : 5 broken limestone. After setting
12 hrs, the loose cem was removed by water and brushes.

Pacific Borax Go's factory, Bayonne, N. J. Finished to represent coursed
ashlar, by inserting wooden strips in the molds and dressing the faces with
a pneumatic hammer. One man could dress from 300 to 600 sq ft in 10
hours by machine, 100 to 200 by hand. Good effect.

"Mr. Cummings produced a good finish by going over the surf with a
wire brush while the cem was still green."

Utica & Mohawk Valley Ry viaduct, Herkimer, N. Y., and viaduct over
rys at Jacksonville, Fla. "A very superior finish." For a hard wall, wet
the surface and apply a thin 1 : 2 mortar with a brush. Rub surface with
a piece of grindstone or carborundum, removing board marks, filling pores
and producing a lather on the surf. Go over this lather, before it dries,
with a brush dipped in water.

For a green wall (molds removed in less than 7 days,) use a thin grout of
neat cem, instead of the 1 : 2 mortar. Remainder of process as above.

Use smooth molds, deposit wet cone directly against them. After re-
moving molds, float the surf with a wooden float, using only sufficient
mortar to fill the pores and give a smooth finish.

44 c. Corrosion.

Chicago. Iron rods, in limestone cone slabs which had covered sidewalk
vaults for 8 or 10 yrs, rust-free. E. L. Ransome.

* See t 4, p 1103. t Unreliable.



1156 CONCRETE.

For Directory to Experiments, see pp 1135-9.

Obelisk, Central Park, New York, small piece of iron set in mortar taken
from the base. Bright after 2300 yrs. Iron drift bolts, from bed of cone
at a lighthouse in the Straits of Mackinac, rust-free 20 years after laying.
Wm. Sooy Smith.

Osage River bridge, Mo., Iron cyl piers filled with Louisv cem limestone
cone. Iron absolutely free from rust after 7 yrs service. Albert A. Tro-
con, E R, Vol 38, p 273.

Steel rods, sheet steel and expanded metal, embedded in cone blocks
3" X 3" X 8", and unprotected steel, all enclosed in tin boxes, and exposed,
for 3 wks, one portion to steam, air and carbon dioxide, one to air and
steam, one to air and carbon dioxide, and one to atmosphere of testing room

Conclusions :

Cone must be dense, and be mixt wet. Neat cement a perfect protection.

With cinder cone, corrosion due mainly to iron oxide, not to sulfur.

Cinder cone, if dense and well rammed, about as good as stone cone.
- Steel must be clear when imbedded.

Steel must be coated with cem before being imbedded. Otherwise there
will be more rust than steel in the result. Prof. Chas. L. Norton, Rep No.
2, Ins. Engng Expt Sta., Boston.

Grenoble, France. Reinfd cone water main, Monier, 12" diam, l%o*
thick, steel framework of M and V\Q" steel rods. 15 yrs in damp ground.
Adhesion perfect. Metal absolutely free from rust.

Berlin. Reinfd cone retaining wall. After 11 yrs use, metal found free
from corrosion, "except in some cases where the rods were within 0.3 or
0.4" from the surf." Effect of the cone, in preserving metal, not due to the
exclusion of air. "Even thq the cone be porous and not in contact with
the metal at all points, it will still filter out and neutralize the carbonic
acid and prevent corrosion." S. B. Newberry, E N, Vol 47, '02, Apr 24, p 335.

Links from anchorage of a suspension bridge partly built by Roebling
in '55. Removed '75. Perfect. G. Bouscaren, E R, Vol 38, p 253.

Niagara suspension bridge anchorage. No rust where h'mestone was not
in contact with metal and where no movement had taken place. Perfect
after 25 yrs. L. L. Buck.

45

45. Wm. B. Fuller, A Treatise on Concrete, by T and T, '05.
45 a. Moisture ; effect of tamping :

Moisture Dry 6 % Saturated

Reduction of vol, %, by tamping 9.6 18.8 8.8

Max volume in sands, when water is betwn 5 % and 8 % by wt.

45 b. Voids, between spheres of uniform diam ("large masses of
equal sized marbles") could not be reduced, by pouring and tamping into
a vessel, to less than 44 % of the mass. See f 30, p 947 6.

46

46. National Fire Protection Assn, Rept of Comm, '05.

46 a. Fire tests.

Specimens. Beams 8" X 11 H" X 6 ft, each with 3 plain round steel
rods, 6 ft 6" long, imbedded 1", 2" and 3" from bottom of beam. Port cem,
Aggregates Mixtures Voids, %

Screened coarse gravel 1: 2:3, 1: 2.5 : 5, 1: 3.5 : 7 35

Limestone, < 1M" " 42

Screened red granite, < 1 W " 40

Ordinary cinders 1:2:5, 1:2:6

Wet mix. Specimens 45 to 48 days old.

Treatment. 3 hours in furnace; temps 1900 to 2000 F.

Results.

46 b. Conductivity was lowest in the cinder concrete and in the
richer cones. Otherwise materials had no important effect.

46 c. Strength of rods impaired 25 % at 770 F. Av time
reqd to reach 770; I" imbedment, 1 b; 2", 2 hs; 3", 2.5 ha.



EXPERIMENT AND PRACTICE. 1157

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

46 d. Couc did not break or chip under fire; but lost practi-
cally all strgth to a depth of 4" from sides and bottom, and softened per-
ceptibly thruout. The cem and most of the stone were thoroly calcined at
surf, and, to a diminishing extent, to a depth of 4". In all cases, a little
water appeared in cracks running across the beams, especially with
the richest mixtures and with temp at 212 F.

46 e. Recommendations. Materials should be well mixt, wet,
by machine, and well tamped. Imbedment should be < 2"; in important
cases, 3".

47

47. John H. Quiiiton, U. S. Geol Surv, "Expts on Steel-cone Pipes
on a Working Scale," U. S. Water-Supply and Irrigation Paper 143, '05.

47 a. Permeability. To determine availability of such pipes under
pres, for U. S. Reclamation Service.

Specimens. Seven reinforced hand-mixed cone pipes, 5 ft diam, 6*
thick, 20 ft long; each made in one section; one, same dimensions, in 4
sees. Skilled workmen. In 3 of the 7 pipes, and in 3 of the 4 sees of the
8th pipe, lime was used in the mixture.

The pipes varied greatly in texture. One of them "seemed to be of a
crumbly nature, and it would have been easy to cut a hole through it."
Another was "exceedingly hard."

Treatment. The pipes were tested with and without inside linings of
cem and sand, etc, with and without lime paste. The Sylvester soap-and-
alum wash (p 928), P and B waterproof paint, and other paints were tried;
and clay was stirred up in the water within the pipes. Pressures up to
70 Ibs/Q" = 161.5 ft. head.

Results.

47 b. In spite of all precautions, the pipes leaked, especially along tamping
seams. Leakage decreased greatly under pres, as percolating
water filled the pores with laitance; but in the mean time the leakage may
be sufficient to damage foundations of pipe.

47 c. Dry mixtures gave the more permeable cone.

47 d. With carefully graded gravels, it was found difficult to secure
uniform distribution of the din sizes.

47 e. Keep cone shaded while mixing and placing.

47 f. Interruptions to work are least dangerous with wet mixtures.
In tamping, avoid displacement of reinforcement.

47 g. Make reinforcemt strong enough to protect cone against ten-



47 h. Soap and alum mixture of advantage in making cone; but
%" plaster found advisable on inside, in two coats, the first with lime paste,
to retard setting; the second (applied when the first is dry) to be troweled
smooth. When dry, apply thick neat cem wash.

47 i. Reinfd cone pipes not recommended for heads over 70 ft (30 Ibs
/Q"). For short dists, special precautions may justify 100 ft (43 Ibs/D").

47 k. Cone pipes liable to crack, especially along tamping seams;
but, even if cracked, probably drier and more durable than other kinds.

47 1. When the pipes were broken up, rust appeared upon only 1 rod,
which was rusted all around for a length of about 1 W , where a large and
long-continued leak had occurred. The pipe had been lined with a mortar
containing sal ammoniac (ammonium chloride) and iron filings.

48

48. Considere. Beton und Eisen, '05, Vol 3

48 a. Ductility.

Specimens. Mixture, 400 kg Port cem, 0.4 cu m sand, 0.8 cu m lime-
stone screenings. Beams 15 X 20 cm, 3 m long. Tension side reinfd with
2 iron bars 16 mm round, and 3, 12 mm rd. Bendg mom constant thruout
measd length.

Treatment. One beam kept in water, one under damp sand, 6 moa



1158 CONCRETE.

For Directory to Experiments, see pp 1 135-9.

Results. Max unit stretches

kept under water 0.00107

damp sand 0.00050

No cracks discovered, altho the surf was smoothed with cem.
Strength unaffected.

49

49. R. Feret, "A Treatise on Concrete, Plain and Reinforced," by
Taylor and-Thompson, '05.

49 a. The injurious action of sea water is due chiefly to the sulfuric
acid of the dissolved sulfates; hence, the cem should contain as little
gypsum (lime sulfate) as possible. Port cem should be low in aluminum
and in lime. The presence of puzzolanic material is advantageous. The
cone should be dense and impervious.

50

50. Prof Ira H. Woolson, Report to Astoria Light, Heat and
Power Co., '05.

50 a. Character ; strength.

Strengths in Ibs/D"

Tensile Compressive

Port Cem, 1:2:4.



Max Av Min Max Av Min

Sand & broken limestone 176 161 153 2000 1753 1441

Crushed* & broken limestone 282 194 138 3400 2449 2040

50 b. Sand contained < 1 % loam; all past %" sieve; 75 % past 20
mesh sieve. Hudson R bluestone (limestone) passing 1 M" screen, retained
on %" screen. Cone tampt wet in molds, 1 or 2 days in air, 5 or 6 in water.
Air dried 4 to 7 wks. Results, see 50 a.

51

51. Prof R. C. Carpenter, Cornell Univ, Sibley Jour of Eng'g,
Jan, '05.

51 a. Retardation of setting ; gypsum (lime sulfate) CaSO 4 ,

and calcium chloride, CaCl2. Both ground dry with the clinker.
Initial set; paste bears a rod Via inch diam, loaded with M lb.
Final set; " y 34 ' 1 lb.

Time, in both cases, reckoned from time of mixing, and given in mins.
Results. Percentage by weightf

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 5.0 6.0 7.0
Time in minutes

Initial CaSO 4 2 6 ... 80 24 29 30 27 28 27 19 18

CaCl 2 2 115160167127103 45 97.. 73 68..

Final CaSO 4 52 87 ... 157 114 79 69 72 45 59 37 59

" CaCl 2 52 274 272 234 212 180 182 185 .. 160 145 ..

51 b. E. Candlot (Ciments et Chaux Hydrauliques) found that concen-
trated solutions of CaClo (such as 100 to 400 grams per liter) accele-
rated setting and hardening.

51 c. Addition of slaked liuie to a cem containing gypsum which,
with time, has lost its retarding effect.

Initial, mins Final, mins



2 % gypsum, no lime 12 15

' '' +5% " 120



300



2 to 5 % of lime is useful in this respect, but not without the gypsum.
The lime does not diminish the strgth.

52

52. Jas. C. Hain, Chic, Mil and St P Ry. E N, '04/Apr 28, p 413
E R, '05, Jan 28, p 103. Sand; size and cleanliness.

*%" crusher screenings; 87 % past M" sieve, 40 % past %" sieve,
t 1 % = about 4 Ibs CaCl 2 to a barrel of Port cem.



EXPERIMENT AND PRACTICE. 1159

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

Specimens.

52 a. Impure sands.

1 : 3 Port cem mortars, made with

(a) sand of smooth rounded quartz grains, mixt with larger fragments
of limestone shells, 92 % past No 24 sieve, 28 % past No 50;

(b) "St Paul standd sand," 54 % past No 24; 11 % past No 50;

(c) "Ottawa standd sand."

Results :

Relative tensile strgths (a) 100; (b) 137; (c) 107.5.

Sand (a) made excellent cone in a draw-span center pier.

1 : 3 Port cem mortars, with sand containing 3.2 to 15 % clay; strgths
< with clean sand. With nat cem 1 : 3, and Port 1 : 2, the results were
generally favorable to the cleaner sand.

Sand with 6 % clay gave stronger mortars before than after washing.

Sands, to which 2 to 20 % rich loam had been artificially added, gave
mortar testing somewhat irregularly but in general higher than those with
clean sand.

52 b. Fine sand, with clay. A sand, all passing No. 100 sieve,
93.2 % passing No. 200 (therefore finer than most cem. See Specfs), and
containing 12 % clay, gave a 1 : 3 Port cem mortar showing, at 6 moa
and 1 yr, nearly the same tensile strgth as similar mortar made with "Ot-
tawa standard sand," but the mortar was weaker at shorter periods.

53

53. Jas. C. Hain, Engr of Masonry Constn, Chic, Mil and St P Ry,

E N, '05, Mar 16.
Oil. Tests by Oeo. J. Oriesenaner.

53 a. A neat Port cem briquet, 2 yrs old, exposed to occasional
drippings of signal oil, began to disintegrate in 10 mos; but no recent cone
structures were found perceptibly injured by oil. A cone floor, upon
which lubricating and lighting oils had been stored for 6 yrs, was apparently
unaffected. Oil penetrated about Vic". A piece of this floor, in oil 10
mos, still sound.

53 b. Port cem; neat; 1:3 sand; 1:3 limestone screengs; 18 bri-
quets each; 4 days in air. Then saturated daily with signal oil; later
less frequently. Cracks appeared in the 1 :3 specimens in 2> mos; in
neat specimens in 5 mos. All the briquets disintegrated eventually.

53 c. Port cem ; 54 briquets, neat; 36 briquets 1 : 3 sand. 7 d in
air. Then saturated daily with oil; later, less frequently. Oils used;
extract lard, whale, castor, boiled linseed, crude petroleum, signal. Cema
made from limestone and clay, marl and clay, limest and slag. Lard oil
disintegrated most of the briquets in from 2 wks to 2^ mos, but some re-
mained sound for 9 mos. Signal oil (animal and mineral mixt) had nearly
the same effect. Whale and castor oil affected only a few briquets; while
petroleum and boiled linseed disintegrated no briquets. Petroleum di-
minished strgth somewhat. Boiled linseed formed a protective coating
and did not affect strgth. As a rule, the neat briquets yielded first. In
general, briquets of limestone and slag yielded most; those of limestone
and clay least.

53d. Silica cem; neat, 1:1, 1:2, 1:3, sand. 1 briquet each.
2 yrs in water; 20 days in warm air. Signal oil 2 yrs. First 3 briquets
sound; 1 briquet (1:3) disintegrating.

53 e. Linseed oil, Sylvester's process (p 928), paraffine, and water glass
(soda silicate) were applied, as coatings, to the briquets, but all failed
to protect them against the action of the oils.

53 f. Rich cone, well made of good materials and well set and sea-
soned, is best for resisting oil. In practice, cone structures are rarely,
if ever, saturated with oil, as were these specimens.

54

54. < lists. A. Matcham, Nat Builders' Supply Assn, E R, '05, Apr
15, p 435.

54 a. Corrosion.



1160 CONCRETE.

For Directory to Experiments, see pp 1135-9.

Specimens and treatment. 6-inch cone cubes, 3 yrs old, with 3*
steel cubes embedded.

Two cubes, with uiipainted 3" steel cubes embedded, exposed to
summer and winter weather, and sometimes covered with snow a ml ice.

Results.

Steel uninjured. Crushing strgths, 2920 Ibs and over 4166 Ibs/D".
One 6" cube, with 3" steel cube (painted with metallic paint) embedded,
placed in bottom of river. Steel uninjured. Paint disappeared.
Crushing strgth, 2907 lbs/D".

55

55. Prof Ira H. Woolson. E N, '05, Jun 1.

55 a. Absorption.

Specimens. 8" cubes, 1:2:4, 3 weeks old, kiln dried 13 days at
120 F.

Part with sand with < 1 % loam; all past 0.125* screen ; 75 % past
20-mesh sieve. Part with %" limestone crusher screenings; 87 % past M"
screen; 40 % past 0.125" screen; sand and dust, enough to fill voids. Stone
past 1 y? ring.

Results.

Av absorption -, 4 hours, 2.87 %; 24 hrs, 2.95 % ; 48 hrs, 3.33 %. No
marked din* betw sand and screenings.

56

56. W. C. llond, Univ of Kansas. E N, '05, Aug 10.
Clay and I .on in ; strength and absorption.

56 a. Port cem with (a) standd Ottawa sand, 1:3; (b) 2 to 20 % of the
sand replaced by clay or loam. At 90 days, relative strgths; in general:
(a) 100; (b) 94 to 125.

56 b. Up to 6 or 8 % clay or loam, there was no increase of absorption,
with loam; and about 10 % decrease, with clay. With higher per-
centages, the absorption increased somewhat.

57

57. Eng News, '05, Sep 28.

57 a. Permeability.

Reinforced concrete cistern, 75,000 gals. 1:2:4, Port cem,
river sand, gravel. 1" layer of 1 : 1 mortar on bottom. "Walls
washed with 3 coats neat cem gront, cream consistency, put on with
whitewash brush after walls were well wetted. Each coat dried for 24 hrs.
If too wet, the coating crackt. If too dry, it could not be brusht on. For a
few days after filling, lost % 6 " in depth per day. Perfectly tight since.
Cistern built with outside air at temp below 20 F; but was covered
with boards, .and two coke salamanders were used.

58

58. Prof Ira H. Woolson, E N, '05, Nov 2.

58 a. Flow.

Specimens. Cols, 4" diam, 12" long, formed in steel tubes, W to
J4" thick, and allowed to set and remain there for 17 days, when the cone
appeared very hard. Cone remained in tubes during tests.

Results. Under loads of 150,000 Ibs, the cols in the stouter tubes were
merely shortened < W\ but under loads of 120,000 to 150,000 Ibs, the
cols, in some of the lighter tubes, were bent out of shape and shortened by
3 y?, their diam increasing from 4" to about 5". Upon removal of the tubes,
the cone was found unbroken, solid and perfect !

59

59. J. M. Itraxtoii, U. S. Asst Engr. Reports, '05-6. E N, '08,
May 14, p 525.

Corrosion in sea water.



EXPERIMENT AND PRACTICE.



1161



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

59 a. }/%' steel rods imbedded in 4 cone blocks made with coral sand and
broken brick. 2 blocks in 4 ft of sea water; 2 in a dry closet, both for more
than a yr. The rod in one of the dry blocks showed signs of rusting. The
others were as bright and smooth as when placed.

59 b. 30 blocks, 12" X 12" X 6"; Port cem, 1:3:5, broken brick.
Made under usual working conditions. %" twisted steel rod, 8" long, in
cen of each block. 20 blocks with coral sand, 10 with ordinary quartz
sand. Half of each placed in ocean, half in air without roof. Broken after
1 yr, 3 wks. In all the blocks placed in the ocean, the rods were found in
perfect condition. All the others were more or less rusted.



Baldi



60

rin- Wiseman, Instn



C E Procs, '06, Vol 163,



6O. Win.

p319.

6O a. Puddling- effect of water flowing thru cone discs, 13" diam, 6"
thick, 1 : 4 Port cem, crushed gravel passing 1" ring. Sp gr of cone 2.23,
140 Ibs/cu ft. In wooden molds 10 wks. Water, for pres, pumped from
chalk formation, hardness reduced from 18 to 6. Air temp 12 to 15 C
= 54 to 59 F. Pressures, 24 to 60 Ibs/Q" = 55 to 139 ft. Leakage as
per Fig 4. Toward the close of the expts, small stalactitic growths



Days
Fig 4. Puddling.

formed on bottom of test piece, and leakage was absorbed by evaporation.
Near the surf, the water, under high pres, dissolved out some of the material,
but deposited it in the pores farther on, where the pres had been reduced by
passage thru the block.

61

61. Sa lord E. Thompson. A S T M, Procs, Vol VI, 1906, p379.
61 a. Consistency ; effect upon density,* permeability
and compressive strength.

Density and permeability specimens, 21 days old; comp strgth specimens
5M mos.

Specimens.

Atlas Portland cem; Newburyport sand, sp gr = 2.65; trap, sp gr = 2.78.
1 : 2.3 : 4.6 by vol; 1 : 2 : 4 by wt.

Consistencies used. Water, % t

Dry. Like damp earth; water glistened on surf under hard

ramming 5.4

Medium. Looked wet when mixed. Did not flow in mixing

box. Slightly quaking 6.9

Wet 9.2

Very wet. Like thick soup. Settled to a level in mixing
box. Required scoop shovels for handling. Slightly wet-
ter than usual in building work 11.0

Extremely wet 13.7

* Density = vol of solid particles in unit vol of cone,
t Percentage of weight of cem, sand and stone.



1162



CONCRETE.



For Directory to Experiments, see pp 1135-9.
Results. See Fig 5.




0.4 o.y 9.2 11.0 13.7

Water, Percentage of Dry Materials by*Weight.

Fig 5. Consistency.

For a given consistency, the percentage of water depends upon the
nature of the cem, and upon the size and dryness of the sand grains. A fine
sand, or one with many fine grains, may require twice as much water as
coarse sand requires.

61 b. Elastic modulus. Twelve 12" cubes, deformations measd in
5" gaged length. Averages of 4 specimens, 1:2:4; approx 1, 2, 6 and 17
mos old. Dry, 4,450,000 Ibs/D"; medium, 4,200,000; very wet, 3,000,000.
No appreciable increase of modulus with age.

61 c. Age; permeability. Blocks tested at 21 and 84 days, showed
permeabilities abt as 2 : 1.

61 d. An excess of water washes out fine cem, forming laitance,
reducing strgth and increasing permeability. Thickness of laitance
formation, y s " in very wet mixtures.

61 e. Mr. Tbompson concludes that, in building and other
reinfd work, the cone should be only wet enough ' ' to flow sluggishly around
and thoroly imbed the steel and permit smooth surfaces against the forms,"
and that medium or quaking cone is suitable for ordinary mass cone, such
as foundations, heavy walls, large arches, piers and abuts.

62. A. Black, E N, '06, Aug 30, p 236.

62 a. Character of sand ; strength and absorption.
Specimens. Passing No

170 sieve.

A, crushed gneiss, screened thru y< mesh 90.8 %

B, Cowe Bay sand, much used in and about New York . . 95.8 %

C, fine clean silicious sand 95.5 %

Results. In 7 and 28 days, 1 : 2 and 1 : 3 mortars, A and B gave, in

general, from 20 to 50 % greater tensile and comp strengths than C. In
general, the stronger mortars showed the higher absorptions.

63

63. Alex. B. Moncrieff, E N, '06, Aug 30, p 227.

63 a. Briquets in water 2 yrs, in air 7 days and in oil 6 mos. In general,
neat cem lost from to 36 % strgth, while 3 : 1 gained from to 65.5 %,
by air drying and immersion in oil.

63 b. Briquets in air 7 days; then 6 mos in either oil or water. The neat
cem briquets in oil were from to 55 % weaker than the neat cem in water;
the 3 : 1 briquets in oil were 49 to 79 % weaker than those in water.



EXPERIMENT AND PRACTICE.



1163



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

63 e. Briquets in water 9 wks; others in water 4 wks, in air 1 wk and in
oil 4 wks. With few exceptions, the neat cem briquets in oil were from abt
to 40 % stronger than like briquets in water, while the 3 : 1 briquets were
from abt to 63 % stronger than like briquets in water. Many of the oil-
treated briquets "snapped like flint."

64

64. Prof Arthur X. Talbot, Univ of 111. Bull, Vol IV No. 1,
'06, Sept 1.

64 a. Adhesion and friction. '04.
Specimens and results.

Mix, 1:3:6.

Pull, in lbs/D" of net section;

Elastic limit, in Ibs/D";

Adhesion, in lbs/Q" of imbedded surf:

Johnson bars Round bars



Square bars



1 A" %" W W 3 /s" Yz %"

Pull 71,412 34,500 31,500 21,500 35,656 26,510 20,860

.60,000 58,300 42,500 40,500 45,000 33,300 35,000

595 420 249 315 297 286 325



Elas lim

Adhesion



With all the Johnson bars, the specimens split or broke. All the
plain rods slipped. 6 of the 11 Johnson bars, and 4 of the 11 bars Y"
square, were "struck 6 quarter-swing blows with a 10-lb sledge," reducing
their adhesion by abt 5 to 20 %.

Specimens.

64 b. '05-6. Cylinders, 6" diam, 6" and 12" long; 60 days old. Mixture
of Am Port cems, tensile strgth, neat, 723 Ib/Q" at 7 days; 1 : 3, 354 at 7
ds, 533 at 75 ds; coarse mortar sand; broken^ limestone, screened thru 1"

und,
(T),



0.57
0.55
0.64
0.64
0.72
0.65
0.57
0.54
0.67
0.49
0.32



Rich mixture generally superior. Cold rolled shaftg and tool
steel generally inferior, owing to uniformity of sec and smoothness of surf.

65

65. Jos. W. El 1 ins. Chemist, Commissrs of Water Works, Cincinnati.
E R, '06, Oct 27, p 467.

65 a. Permeability.

Specimens. Port and nat (Louisville) cem; Ohio River quartz sand,
clean, rather fine, quite uniform in size; limestone screenings, with much
very fine dust.

3" cubes;

Port cem; (a) 1 cem : 2 sand, 10 % water; (6) 1 cem : 1 sand : 1 screen-
ings, 11 % water; (c) 1 cem ; 2 screenings, 14 % water.

77



and over M" screen. Metal, elas lira, Ibs/
38,000; Flat, 45,000; Cold rolled shafting


Qf; Mild steel (M), R
(C), 87,000; Tool steel


53,000.






Results.


Lbs/n* im-


No.


Imbedded


bedded surface


of


1<*rt rv+Vk




tests Steel Size Mix ins.


Adhesion Friction j






a f


6 M W round 1 3 5.5 6


372 210 (


6


1


2 4


412 227 (


6


%" round


3 5.5


355 227 (


4




2 4


465 297 (


3


Yz" round


3 5.5 12


373 268 (


4


"


24


404 266 1


3


%" round


3 5.5


402 228 (


3




2 4


414 223 (


3


' 1 1 A X ^" 1


3 5.5 6



1 2 3 4 5 6 7 8 9 10 11 12 13 15 17 18 19 20 21 22 23

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