Journal of the American Concrete Institute, Vol. 18, No. 3

u r q a n n u a l Convention, C I N C I N N A T I , February 24-26, 1947 P.

J O U R N A L

o f the

AMERICAN CONCRETE INSTITUTE

(ACI PROCEEDINGS Vol. 43J

V o l. 18 November 1946 No. 3

C O N TEN TS

Papers and Reports... 209-336 Lining of the A lv a B. Adams Tunnel...RICHARD J . W ILLS O N 209 Repairs to Spruce Street Bridge, Scranton, Pennsylvania ...

...A . BURTON C O H E N 241 Studies of the Physical Properties of Hardened Portland Cement Paste—

Part 2 ... T. C . POWERS and T. L. BRO W N YARD 249

Job Problems and Practice... 337-344 Design of Rectangular Tied Columns Subject to Bending. . . F. E. RICH ART 337 Cleanouts for Forms... C H A R LES M A C K L IN , R. F. BLAN KS 338 Differences in Characteristics of Concrete in the Wet and Dry State...

F. L. FITZPATRICK 339

Current Reviews... 345-352

News Letter.

A C I B O A R D A P P R O V E S P L A N S FO R M O R E S ER V IC E • New Members 9 Who's Who 9 Honor Roll 9 Fritz Emperger • Kanwar Sain 9 Henry C. Turner

1-20

to p ro v id e a co m ra d e sh ip in fin d in g the b e st w a y s to do c o n c re te w ork o f a ll kin d s a n d in sp re a d in g th a t k n o w le d g e

A D D R E S S : N E W C E N T E R B U I L D I N G , D E T R O I T 2 , M I C H .

f t e n L . . . u _______ L i _ .* •

S1.25 per copy

Extra copies to members S I . 00

- 1 V— a n . C I N C I N N A T I , Feb ru ary 24-26, 1947 p* 9 5 1H(ohT-

J O U R N A L

o f the

AMERICAN CON CRETE INSTITUTE

(ACI PROCEEDINGS Vol. 43)

V o l. 18 November 1946 N o. 3

C O N T EN TS

Papers and Reports... 209-336 Lining of the A lv a B. Adam s Tunnel... RICHARD J . W IL LS O N 209 Repairs to Spruce Street Bridge. Scranton. Pennsylvania ...

. . ...A . BURTON C O H E N 241 Studies of the Physical Properties of Hardened Portland Cement Paste—

Part 2 ...T. C . POWERS and T. L. BR O W N YA RD 249

Job Problems and Practice... 337-344 Design of Rectangular Tied Columns Subject to Bending. . . F. E. RICH ART 337 Cleanouts for Forms...C H A R LE S M A C K L IN , R. F. BLAN KS 338 Differences in Characteristics of Concrete in the Wet and Dry S tate...

...F. L. FITZPATRICK 339

Current Reviews... 345-352

News Letter... 1-20 A C I B O A R D A P P R O V E S P L A N S FO R M O R E S E R V IC E •

New Members 9 Who's Who 9 Honor Roll 9 Fritz Emperger 9 Kanwar Sain 9 Henry C. Turner

to p r o v id e a c o m ra d e sh ip in fin d in g th e b e s t w a y s to d o c o n c re te w ork o f a ll k in d s a n d in s p re a d in g th a t k n o w le d g e

A D D R E S S : N E W C E N T E R B U I L D I N G , D E T R O I T 2 , M I C H .

i f . s G b y the v Mf — Ssmbassseer t o iu n s S1.25 per copy

Extra copies to members $ 1 .0 0

DISCUSSION

Discussion closes March 1, 1947

Sept. J l. '46 Reinforced Concrete Columns under Combined Compression and Bending— H arold E.

Wessman

Effect of Moisture on Thermal Conductivity of Limerock Concrete— M ack Tyner

Cement Investigations for Boulder Dam— Results of Tests on Mortars up to A g e of 10 Years

— Raymond E. Davis, Wilson C . Hanna and Elwood H . Brown

A n alysis and Design of Elementary Prestressed Concrete Members— Herman Schorer O ct. Jl- '46 Minimum Standard Requirements for Precast Concrete Floor Units ( A C I 711-46)

— Report of A C I Committee 711, F. N . M enefee, Chairman

Recommended Practice for the Construction of Concrete Farm Silos (A C I 714-46)

— Report of A C I Committee 714, William W . Gurney, Chairman The Durability of Concrete in Service— F. H . Jackson

W ear Resistance Tests on Concrete Floors and Methods of Dust Prevention—

— Georg Wastlund and Anders Eriksson

Nov. J l. ’46 Lining of the A lv a B. Adam s Tunnel— Richard J . Willson

Repairs to Spruce Street Bridge, Scranton, Pennsylvania— A . Burton Cohen

Discussion closes Ju ly 1, 1947

Studies of the Physical Properties of Hardened Portland Cement Paste— Parts 1 and 2

— T. C . Powers and T. L. Brownyard

Resuming, with this volum e y e a r, the former J O U R N A L publication schedule of 10 issues instead of 6 for the y e a r, the Supplem ent, issued in recent years with the N ovem ber issue, will be m ailed with the Decem ber J O U R N A L . It will contain Title P a g e , T a b le of Contents, Closing Discussion and Indexes, concluding the volume otherwise com pleted in the issue of the previous June.

[ O U R N A L

o f the

AMERICAN CONCRETE INSTITUTE

Vol 18—No 3 ~ November 1946 (Proceedings Vol. 43)

P u b lis h e d by th e A m e r ic a n C o n c r e t e In s titu te fe n tim es a y e a r . T h e In stitu te w a s fo u n d e d 1 9 0 5 / in c o rp o ra te d in th e D is tric t o f C o lu m b ia in 1 9 0 6 a s T h e N a t io n a l A s s o c ia tio n o f C e m e n t U s e r s ; th e n am e c h a n g e d 1 9 1 3 b y c h a rte r am e n d m e n t. It w a s r e in c o rp o r a f e d , w it h n e w sta te m e n t o f o b je c ts , A u g u s t 8 , 1 9 4 5 . T h e J o u r n a l is issu ed m o nth ly, J a n u a r y to J u n e a n d S e p te m b e r to D e c e m b e r ( t h e vo lu m e y e a r S e p te m b e r to J u n e b e in g co m p le te d b y t itle p a g e , c o n te n ts, in d e x e s a n d c lo sin g d iscu ssio n in a su p p le m e n t issu e d th e su b se q u e n t D e c e m b e r) u n d e r th e a u th o rity o f th e

BO ARD O F DIRECTION, A M E R IC A N CONCRETE INSTITUTE

Presiden!

H A R R ISO N F. G O N N E R M A N V ic e Presidents

S T A N T O N W A LKER , ROBERT F. BLAN KS Secretary-Treasurer

H A R V E Y W HIPPLE Regional Directors P A U L W . N O R T O N

R O Y R. ZIPPRODT A LE X A N D E R FOSTER, JR.

H . P. BIGLER C H A R LE S S. W H IT N E Y

HERBERT J . G ILK E Y

HARRY F. T H O M S O N

Directors-af-Large

FRANK H . JA C K S O N H EN R Y L. KENNEDY Past Presidents

R A Y M O N D E. D A V IS BEN M O REELL

M O R T O N O . W IT H E Y R O Y W . CRUM D O U G L A S E. PARSO N S

A s s is ta n t S e c re ta ry FR ED F. V A N A T T A

A ssistan t Treasurer E T H E L B . W ' L S O N

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the A C I J O U R N A L ®

is edited by the Secretary or the , i l l f

Publications Committee under the O ppression p u b licatio n sched ule 0 direction of the Committee fen issues a y e a r -m onthly, Septem­

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ROBERT F. BLA N K S

C h airm an

H A R R ISO N F. G O N N E R M A N

(ex-o fficio )

R A Y M O N D E. D A V IS HERBERT J G ILK EY

A . T. G O LD B EC K FRANK H . J A C K S O N

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A M E R IC A N C O N C R ETE INSTITUTE

N E W C E N T E R B U I L D IN G D E T R Q IT 2 , M I C H I G A N

• The an nual Sup p lem ent, usually issued w ith the N o ve m b e r Journal, w ill be m ailed this y e a r w ith the D ecem ber number. The Supplement w ill contain T itle p a g e , Tab le of Co n ten ts, C lo sin g discussion and Indexes for P ro ceed in g s volume 42, o th e rw ise com pleted w ith the previous Ju n e Jo u rn a l.

• H a v e y o u p ro p o sed one or more of the 591 n e w members since M a y first?

0 Discussion of the p ap ers and re­

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• 4 3 rd A n n u a l A C I Convention, C in c in n a ti, O h io , F e b ru a ry 24, 25 2 6 , 1 9 4 7 . C ir c le those dates on your c a le n d a r.

[

Title 43-10 —a part of PRO CEED IN G S, A M E R IC A N C O N C R E T E INSTITUTE V o l. 43

J O U R N A L

of the

A M E R I C A N C O N C R E T E I N S T I T U T E

(c o p y rig h te d )

V o l. 18 No. 3 7 4 0 0 S E C O N D B O U L E V A R D , D E T R O IT 2 , M I C H I G A N November 1946

Lining of the A lv a B. A d a m s Tunnel*

By RICHARD J. W IL L S O N t

M e m b e r A m e r ic a n C o n c r e t e In stitu te

S Y N O P S I S

The 13.03 mile Alva B. Adams Tunnel, excavated under the Conti­

nental Divide, as a p a rt of the transm ountain w ater diversion plan of th e Colorado-Big Thompson Project, U nited States D epartm ent of the Interior, Bureau of Reclamation, has now been lined w ith concrete. Lin­

ing equipm ent and methods are described.

IN T R O D U C TIO N

The Alva B. Adams Tunnel, excavated under th e C ontinental Divide of the Rocky M ountains in N orthern Colorado, now lined w ith concrete, is capable of diverting 550 sec. ft. of w ater from the watershed of the Colorado River, west of th e C ontinental Divide, to th e eastern slope of th e Divide. The tunnel, which was previously known as the “ Conti­

nental Divide T unnel,” is one of th e principal features of th e Colorado- Big Thom pson Project designed by, and constructed under th e super­

vision of, the U nited States B ureau of Reclamation. The transm ountain diversion of w ater for irrigation of northeastern Colorado prairie lands, is the prime objective of the project and th e diverted w ater will provide 320,000 acre-feet of supplem ental w ater annually for irrigation of 615,000 acres of land. Power structures will m ake use of th e n atu ral fall of th e diverted w ater for generation of 900,000,000 kwh. of electrical energy annually for project operation and general consumption.

When completed the project will include, in addition to the tran s­

m ountain tunnel, several m ajor structures on th e eastern and western slopes of th e C ontinental Divide.

Green M ountain Dam, an ea rth fill stru ctu re on th e western slope, is now completed and in operation. I t is located on th e Blue River, a

*R ec eiv ed b y th e I n s tit u te O ct. 12, 1945.

fA re a F ield E n g in eer, U. S. B u re a u of R e c la m a tio n , G ra n d L a k e, Colo.

(209)

210 JO U R N A L O F THE AM ERICAN CO NCRETE INSTITUTE November 1946 trib u ta ry of th e Colorado River. This dam was constructed for th e purpose of im pounding w ater on th e w estern slope to replace t h a t diverted to the eastern slope by th e Colorado-Big Thom pson diversion project.

Two 12,000 kva. generators installed in an adjoining powerhouse have a capacity of 15,000,000 kwh. of electrical energy m onthly.

Shadow M ountain D am is ano ther earth fill stru ctu re on th e w estern slope. I t ’s reservoir will be connected by channel w ith G rand Lake, th e headw ater of th e Colorado R iver, and together th ey will serve as a regulating reservoir for w ater to be diverted th roug h th e tunnel.

G ranby Dam , located some 8 miles dow nstream from Shadow M oun­

ta in Dam , is th e th ird m ajor stru ctu re on th e w estern slope, and has n o t y et been completed. I t also will be an earth fill stru ctu re and will func­

tion as the storage reservoir for w ater to be diverted to th e eastern slope.

Being 85 feet lower th a n the Shadow M ountain-G rand Lake diversion reservoir, w ater will have to be pum ped from th e storage reservoir to th e diversion reservoir.

W ater, afte r passing through th e Alva B. Adam s Tunnel to th e eastern slope of th e Divide, will be handled in closed conduit, siphons, open canals, and other tunnels on its way to th e foothill reservoirs. T he fall will be utilized in th e generation of power.

TH E T U N N E L

Excavation of th e perfectly straight 13.03 mile Alva B. Adams T unnel was begun in Ju n e 1940 and completed in June 1944, afte r nine m onths delay due to lack of m aterials as a result of the war. The tun n el as drilled, has a min. dia. of 11.75 ft. in unsupported ground and 12.75 ft.

in supported ground. I t slopes from west to east 0.155 ft. per hundred ft., m aking th e east portal 107 ft. lower th a n th e west portal. The tunnel was excavated from the two portals, w ith ou t in term ediate shafts or adits; th e longest tunnel in th e U nited S tates to be excavated in this m anner. Upon being “ holed thro u g h ” it was found th a t th e tun nel grade and line were off only %-in. and 7 / 16-in. respectively, afte r having been extended five miles from the west portal and eight miles from th e east portal.

The tun n el was lined w ith concrete to a finished circular section having an in tern al diam eter of 9.75 ft. Lining was sta rte d N ovem ber 16, 1944, discontinued for 3 m onths in 1945 due to m anpow er shortages, a n d com pleted F ebru ary 28, 1946.

L IN IN G O P E R A T IO N

C oncrete lining of th e tunnel was done by con tract u n d er th e sup er­

vision of the B ureau of R eclam ation. T he w estern half of th e w ork was done by th e Stiers Bros. C onstruction Co. of St. Louis, M o .; th e eastern

LIN IN G O F THE A L V A B. ADAM S TUNNEL 211 half by the S. S. Magoffin Com pany of Englewood, Colo. These con­

tracto rs had previously completed the excavation of th e tunnel.

The m ajor portion of the equipm ent employed by th e two contractors in the lining work was identical and lining procedures were correspond­

ingly similar. Cem ent and aggregates were delivered to batching plants a t the tunnel portals where they were proportioned in one-cubic yard dry batches. The batches were placed in 24-in. gage specially con­

structed cars and transported to handling and mixing equipm ent in the tunnel. W ater was added a t the mixer and concrete pum ped into forms by Rex pum pcrete equipm ent.

The batch cars and the handling, mixing and placing equipm ent were specially designed for th e work, clearance inside th e tunnel being the controlling feature of the design. The equipm ent, or so-called “ string,”

w*as interconnected and movable as a u n it on the 24-in. gage tunnel track.

In Fig. 1, there can be seen, from left to right; a batch car; the transfer conveyor and transfer hopper; the mixer conveyor and mixer; th e pum p­

crete conveyor and pum pcrete machine, w ith 2-cubic yard horizontal remixing drum ; and an air winch m ounted on trucks ahead of and attached to the front of the pum pcrete m achine carriage.

On th e east end of th e work, b atch cars were pushed to th e foot of the incline track leading to the receiving hopper. From this point they were pulled up the incline and spotted over the receiving hopper by cable and electric hoist. On the west end of the work, batch cars were pushed up th e incline and spotted over th e batch receiving hopper by electric locomotive. The batch, on being dum ped frpm th e b atch car into the receiving hopper, fell onto the transfer conveyor and was elevated to th e transfer hopper. From th e transfer hopper it fell onto th e mixer conveyor and was elevated to th e mixer. The mixed concrete was discharged from th e mixer onto the pum pcrete conveyor and elevated to the remixing drum of the pum pcrete machine. The action of th e re-

Fig. 1— The "string." Handling, mixing, and placing equipment was inter­

connected and traveled as a unit on the 24-in. gage tunnel track.

212 JO U R N A L O F THE AM ERIC AN CONCRETE INSTITUTE November 1946 mixing drum forced concrete into th e pum p, which in tu rn forced it through 7-in.pipe to th e forms.

The lining was placed in two operations: first th e lower 66 degrees of the circular section, comprising the in v ert (Fig. 2) and second, th e lining of the arch and sidewalls. Concreting on th e east end of th e tu n n el began Novem ber 16, 1944 and was com pleted F eb ru ary 15, 1946. Placem ent of concrete on the west end of th e tun nel began April 1, 1945 and was completed F eb ruary 28, 1946. Some 130,000 cu. yd. of concrete were required for th e entire lining.

S C H E D U LE O F O P E R A T IO N S

Confined working space in th e tunnel controlled, to a large degree, th e progress of th e lining work. T he setting of forms, tra n sp o rta tio n of concrete m aterials to the mixing equipm ent, and rate a t which concrete could be placed, were also controlling factors.

B oth contractors worked on a three-shift per day, six-day per week basis. In v e rt concrete placem ent, however, was actually accom plished on a one-shift basis; th e other two shifts being utilized for form work, cleanup, m ovem ent of equipm ent, etc. Arch and sidewall lining was handled on a sim ilar schedule a t first because of a m anpow er shortage.

However, concrete placem ent was later accomplished on two shifts and a three-shift basis appeared possible had m anpower been available.

A G G R E G A T E S

Aggregate for th e west end of th e tunnel was obtained from a river deposit some two miles dow nstream from G rand Lake. T he m aterial consisted of durable sem i-angular sand and well rounded gravel. O ver­

burden was no t excessive and was removed from the deposit by stripping.

The aggregates were washed and separated by screening in to th ree sizes:

sand, No. 4- to M-in. gravel, and % - to 1 ^ -in . gravel, all of which were very satisfactory. The average fineness modulus of the sand was 2.90.

Rock larger th an lj^ -in . was present only in small quantities and was wasted. Aggregates were stockpiled near the tunnel portal.

F or th e east portion of the tunnel lining, and o ther project features in the vicinity, a deposit of m aterial on the Big Thom pson R iver, three- quarters of a mile east of E stes Park, was utilized. P ro curem en t of aggregate for project features on the east side of th e C on tinental D ivide was som ething of a problem. Suitable deposits near the sites of th e work, were few, and the deposit east of Estes P ark was far from ideal. I t was sp o tty in character and contained clay strata, generally coarse sand, and large cobbles and boulders. Sand of satisfactory fineness an d grading could only be produced by utilization of a p a rt of th e overburden of fine

: EXCAVATIONPAY " LIN

LIN IN G O F THE A L V A B. ADAM S TUNNEL 213

c â | 8 f i Q. C* -J=

CN cń

214 JO U R N A L O F THE AM ERICAN CONCRETE INSTITUTE November 1946 sand, silt, and clay. Thorough washing was necessary and, in order to utilize as m uch of the p it m aterial as practicable, large rock had to be crushed.

Specifications provided th a t aggregates from th e deposit n ear E stes P ark be processed into sand and two fractions of coarse aggregate having nom inal sizes of 3/16- to % -in. and to l K - i n - T he processing p lan t as originally erected by the contractor, is shown in Fig. 3. I t em bodied an 18 x 36-in. prim ary jaw crusher set to a jaw opening of 3 j^ in .; a 9 x 36-in. secondary jaw crusher set to a 1-in. opening; a fixed grav ity screen having 3/16-in. elongated openings for initial separation of sand from the coarse aggregate; and a triple-deck g yrato ry screen w ith screens having 1%-in. square, 1-in. round and 3/16-in. elongated openings on the top, m iddle and bottom decks, respectively.

Spray nozzles above the screens proved inadequate for rem oving clay balls from th e coarse aggregate and it was necessary to install a spiral w asher for each size of coarse aggregate.

Sand fell from the gravity screen directly into a bin und er th e screen­

ing tower. From the bin the sand flowed by grav ity to a centrifugal pum p and was pum ped, through a 6-in. pipe line 1,200 feet in length, to the stock pile. All or any p a rt of sand passing the 3/16-in. m esh b otto m deck of the vibrating screen could be diverted to the sand bin or to waste.

Generally the coarse portion passing through th e lower p a rt of th e screen only was wasted. The q u an tity and velocity of th e w ater in th e sand bin Avas utilized in control of silt and clay content.

T he use of jaw crushers in crushing th e hard cobbles resulted in pro ­ duction of a relatively high percentage of flat and elongated particles, m any of Avhich would ju st pass a 1%-in. square opening. As th is con­

dition was thoug ht to d etract from the pum pability of concrete produced w ith th e aggregate, a series of trial concrete mixes was m ade. T he aggregate, then being produced and employed in th e trial mixes, was graded 24 percent, No. 4 to % -in .; 16 percent, to % -in.; and 60 percent, to lj^ -in .

T he trial mixes indicated th a t it was no t possible to ob tain an en­

tirely satisfactory concrete, even Avith as much as 46 percent sand or by use of adm ixtures in reasonable am ounts. C haracteristic mixes illu s tra t­

ing the problem are given in T able 1, mixes A and B. E lim ination of th e oversize in th e to lJ-^-in. aggregate size, mix C, im proved th e concrete characteristics someAvhat, and a reduction in th e q u a n tity of No. 4 to ^g- in. fraction in the No. 4 to % -in. aggregate size, mix D, added to the im provem ent. HoAvever, best results Avere obtained in mix E, b y in­

creasing the —100 mesh fraction of th e sand 4.2 percent, along Avith the previous corrections incorporated in mixes C and D.

LINING

en- by

•atr tie iie f îe

!- e

OF THE A L V A B. ADAM S TUNNEL 215

TABLE1—EFFECT OF AGGREGATEONCONCRETECHARACTERISTICS

216 JO U R N A L O F THE AM ERICAN CONCRETE INSTITUTE November 1946

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LIN IN G OF THE A L V A B. ADAM S TUNNEL 217 W ith th e trial mix d ata as a guide, an effort was m ade to im prove th e grading of the aggregate being processed by securing a finer sand, chang­

ing th e grading of the coarse aggregate, and reducing th e q u an tity of long and flat particles.

A finer sand was produced by wasting portions of th e 4, 8, and 16 mesh fractions of the sand and by inclusion in the aggregate deposit excavation, a layer of fine sand, silt and clay overlying th e m ain de­

posit. Tins layer had previously been removed as stripping and wasted.

Use of the layer called for more thorough washing of th e coarse aggre­

gate for removal of silt and clay and was accomplished by th e spiral washers m entioned previously.

To elim inate th e oversize in the coarse aggregate, th e contractor was perm itted to reduce th e nom inal m axim um size to l}<f in- w ith the understanding th a t all of the larger sizes of th e coarse aggregate would pass a I K in. square opening. The contractor also replaced th e 9- x 26- in. secondary jaw crusher w ith a 2 2 -x 40-in. corrugated roll crusher.

These changes brought about a m aterial im provem ent in th e grading and in th e particle shape of th e aggregate. Studies m ade of th e roll crusher product, and discussed below, showed the coarse aggregate to have fewer flakes and elongated particles w ith rollers set to provide a K - to 1-in. space between rolls. F urther, a t this p articular setting, the coarse aggregate was being produced in th e proportions of 18.1 percent No. 4 to %-in.; 31.2 percent, K - to % -in.; and 50.7 percent, to 134- in. very close to the desired grading.

Resulting aggregate produced mixes which were exceptionally work­

able and it was possible to employ less sand th a n was anticipated. B oth invert and arch and sidewall mixes, adjusted to m eet job conditions are given in Table 1. Mix F was used in the invert lining and was placed and finished w ithout difficulty a t slumps as low as 1 in. Concrete for arch and sidewall lining was norm ally placed a t a slum p of 3% - to 4)^-in.

and was easily handled, placed, and consolidated. Best results on th e job, w ith th e roll crushed aggregate, were obtained with a coarse aggregate grading of 45 percent No. 4 to in. and 55 percent % - to lK -in . T he improved w orkability of the concrete would probably have enabled retu rn to the larger maximum size for pum pcrete work, b u t it was de­

cided to adhere to th e contract com m itm ents, which provided for th e lK -in . nom inal m aximum size.

T est d a ta included in this paper should not be m isconstrued to indi­

cate roll crushers were th e only solution to our problem, b u t th ey did fo rtu n ately provide satisfactory results on this p articular job with local aggregates, the coarser portion being essentially composed of slightly to m oderately weathered gneisses and granitic rocks.

218 JO U R N A L O F THE AM ERICAN CO NCRETE INSTITUTE N o v e m b e r 1 9 4 6

The aggregate p la n t produced a clean and fairly well graded sand, having an average fineness modulus of 2.80, and a clean coarse aggregate, containing 50 to 75 percent of crushed m aterial in th e 3 /1 6- to % -in.

size and 50 to 60 percent in th e % - to lj^ -in . size.

To evaluate th e im provem ent in particle shape, due to use of th e roll crusher, th e relative quantities of flaky and long particles p resen t in th e coarse aggregate produced prior to and afte r in stallatio n of th e roll crusher, were analyzed by the m ethod presented in R oad R esearch B ulletin No. 2, “ T he Shape of R oad A ggregate and I ts M easu rem en t.”

The bulletin was published b y th e B ritish D ep artm en t of Scientific and

T A B L E 2— A STU D Y O F P A R T IC L E S H A P E O F C O A R S E A G G R E G A T E (Percent of to ta l finished product)

D escription of

aggregate P ior to

installation of roll crusher

A fter installation of roll crusher

Size Type Shape R oll set

a t y 2”

R oll set a t 1"

TJnerushed All 59.5 76 .8 2 7 .8

Flakes 4 .4 4 .6 0 .6

Longs 8 .7 4 .4 0 .8

Crushed Crushed 4 0 .5 2 3 .2 7 2 .2

Flakes 6 .3 2 .8 6 .9

Longs 15.0 1.3 2 .8

T otal All 100.0 100.0 100.0

Flakes 10.7 7 .4 7 .5

Longs 2 3 .7 5 .7 3 .6

1 ' U ncrushed All 61.1 57 .2 19.4

Flakes 1.8 1.3 0 .8

Longs 15.4 12.9 3 .0

Crushed All 3 8 .9 4 2 .8 8 0 .6

Flakes 4 .8 2 .8 5 .5

Longs 20.5 11.0 1 8 .4

T otal All 100.0 100.0 100.0

Flakes 6 .6 4 .1 6 .3

Longs 35 .9 23 .9 2 1 .4

hé"- M" Uncrushed All 72.5 28 .9 3 7 .8

F lakes 5 .2 1.0 2 .3

Longs 17.7 8 .3 7 .4

Crushed All 27.5 71.1 6 2 .2

Flakes 4 .3 5 .7 6 .2

Longs 13.2 18.3 4 .1

T o tal All 100.0 100.0 1 0 0 .0

Flakes 9 .5 6 .7 8 .5

Longs 30.9 2 6 .6 11.5

LIN IN G O F THE A L V A B. ADAM S TUNNEL 219 In dustrial Research and M inistry of T ransport. A sum m ary of the results of the study is given in Table 2.

C EM EN T

A T ype I I (modified) cement was used. T h a t for th e east portion was purchased from the Colorado P ortland Cem ent Com pany and tra n s ­ ported in bulk by tru ck directly to th e east p o rtal batching p lan t from th e mill storage silos near L aP orte, Colo. Cem ent for th e west portion was furnished by the M onolith P ortland Cem ent Com pany from a p lan t near Laramie, Wyo. and was shipped by rail in bulk from th e p lan t to a 1500 bbl. storage silo a t G ranby, Colo. From G ranby th e cem ent was trucked 12 miles to the west portal batching plant. T he truck s (Fig. 4) consisted of a standard dum p bed w ith special w ater tig h t cover. Similar trucks were employed on both sides of th e divide in transporting cement and functioned very satisfactorily.

B A T C H IN G

Cem ent and aggregate for concrete were proportioned by weight in m anually operated equipm ent installed in plants erected a t each tunnel portal, (Fig. 5 and 6).

Fig. 4— Cement was transported in standard dump trucks fitted with a specially constructed water tight cover.

220 JO U R N A L O F THE AM ERICAN CONCRETE INSTITUTE November 1946 C um ulative batching hoppers were em ployed in proportioning th e aggregates and separate hoppers in weighing the cem ent. T he b atching p lan t a t th e west p o rtal consisted of a circular cem ent storage bin of 600 bbl. capacity, surrounded b y the three aggregate supply bins and had an

Fig. 5 (top)— The east portal batching plant was in reality two independent structures, one for the batching of aggregates and the other for the storage and batching of cement/

Fig. 6 (bottom)— The west portal batching plant was erected over the tunnel portal.

LIN IN G O F THE A L V A B. ADAM S TUNNEL 221 added feature in th a t it had been erected directly over th e tunnel portal.

All batched m aterials were therefore protected from rain and snow a t all times, a distinct advantage in this climate. The batching p lan t at the east portal was in reality two structures. One housed th e aggregate supply bins and batching equipm ent and th e other, a circular cement storage bin of 1,500 bbl. capacity and cem ent batching equipm ent.

T R A N S P O R T A T IO N O F C O N C R E TE M A T E R IA L S

The weighed concrete m aterials were m anually dum ped from batching hoppers into th e specially constructed 24-inch gauge bottom dum p rail cars (Fig. 7). T he cars were divided into two com partm ents each capable of holding cem ent and aggregate for one-cu. yd. of concrete. In each com partm ent a special open bottom container was built for th e cem ent to keep it separate from th e dam p aggregate and lids were provided to protect it from m oisture in th e tunnel. T he containers were deepened 4-in. more th an shown in Fig. 7, to accom m odate th e cement, which was bulked due to batching. To avoid loss in transfer of cem ent from batcher to cars, a canvas tube attach ed to th e botto m of th e cem ent batching hopper was employed.

On th e east portion of the work, six car trains, pulled by 8-ton b a tte ry electric locomotives, transported dry-batched m aterials for 12 cu. yd.

of concrete into the tunnel. Six such train s were kep t in service during concrete placem ent operations. On th e west portion of th e work, both electric and diesel locomotives were used. Diesel locomotives hauled 10 cars (20 cu. yd. batches) into the tunnel. Two such trains on the west side were in service during placement. In using th e electric loco­

motives, 4 eight-car (16 cu. yd.) trains were required. Sidings, or pass­

ing tracks, a t intervals throughou t the tunnel, perm ited passing of loaded and em pty trains. A movable siding or “ California Switch,”

located ju st to th e rear of th e receiving, mixing, and placing equipm ent, was employed in switching em pties from the equipm ent and loads to the equipm ent. Switching in both ends of the tunnel was accomplished by b attery electric locomotives.

C L E A N U P O P E R A T IO N

The m ajor portion of th e cleanup work was com pleted before placing operations in the tun n el in v ert began and consisted of removing loose rock, m ud, and debris. However, such m aterials and w ater th a t accu­

m ulated after th e original cleanup, were removed ju st prior to th e placem ent of th e in v ert concrete by hand shovel, brooms and pumps.

M aterial in the shoulders a t th e sides of th e in v ert (Fig. 2) was broken tunnel rock composed of coarse fragm ents em bedded in finer m aterial.

222 JO U R N A L O F THE AM ERICAN CO NCRETE INSTITUTE November 1946

I t was densely com pacted, and as atte m p ts a t fu rth e r consolidation by mechanical m eans resulted m ore in loosening of th e m aterial th a n in its consolidation, this corner fill was allowed to rem ain in place.

The in v ert lining was placed in advance of th e arch an d sidewall lining, consequently some accum ulation of debris, rock, etc., occurred before th e arch and sidewall lining was placed. J u s t prior to th e place­

LIN IN G O F THE A L V A B. ADAM S TUNNEL 223 m ent of arch and sidewalls, loose rock was barred down, and debris, mud, w ater and th e scale or encrusted m o rtar on steel supports, were removed.

In supported ground, all collar braces were removed, lagging was removed insofar as practicable, and th e rem aining lagging was tightened.

T U N N E L D R A IN A G E

Flow of w ater into th e tunnel from surrounding rock was considerably less th an was originally anticipated. G routing of the rock, as the head­

ing advanced during excavation, was successful in reducing th e flow so th a t drainage was not a m ajor problem. However, th ere were some areas th a t needed atten tio n in this respect and th ey were handled by various m ethods. W here flow from sh attered rock or num erous fissures was encountered, tile drains (Fig. 2), parallel to th e center line of the tunnel, were laid in gravel filled trenches prior to placem ent of th e invert.

Drainage from th e trenches was accomplished by 2-inch pipe extending from trench through lining into tu nnel invert. In areas more or less confined to flow from a continuous fissure, a box filled w ith gravel was used to cover th e m ain flow from th e fissure, and a pipe from th e box through concrete lining served as a drain from th e fined tunnel. In other cases, where flow was from a spring or from a single fissure, a hole drilled into the w ater course served for installation of a 2-inch pipe which extended through th e concrete fining.

In all of th e above instances pipe was set prior to th e placem ent of concrete. Areas in the tunnel showing little flow, b u t some dam pness, were provided w ith drainage by drilling 2-in. weep holes through th e com pleted fining.

IN V E R T FO R M S

On th e east end of the tunnel, wooden invert forms (Fig. 8) were em ­ ployed. T hey consisted of 20-foot longitudinal sections, constructed of 3-in. lum ber, nine or twelve in. in w idth, depending upon the dep th of th e excavated tunnel bottom .

E ach end of th e tw enty-foot sections was notched and steel plates were provided on th e outside of th e form for assuring a tig h t fit between sections and for m aintaining adjoining sections on fine and grade. A spreader, eith er 2- x 8- or 2- x 10-in., depending upon use of 3- x 9-in. or 3- x 12-in. longitudinal form sections, was set between th e parallel sec­

tions of th e forms and th e forms were then pulled together w ith a Coffin jack. Wedges under th e forms provided adjustm ent for grade and shores braced against tunnel walls provided ad ju stm ent for fine and prevented the forms from floating. After forms had been set and shores placed, th e Coffin jacks were removed. The spreaders between parallel

224 JO U R N A L O F THE AM ERICAN CONCRETE INSTITUTE N o v e m b e r 1946

sections of forms were removed ju st ahead of concrete placem ent opera­

tions.

In v e rt forms in th e west portion of th e tun nel consisted of stan d ard 9- in. paving forms and were held in place by anchor bars drilled into th e tunnel walls as shown in Fig. 9. S etting of forms, spacers, blocking, etc., was similar to th a t employed in th e east portion of th e tunnel.

In v e rt forms were generally left in place 24 to 48 hours, depending on the am ount of invert placed during a day and the need for form s for the following d a y ’s work.

A R C H A N D S ID E W A L L FO R M S

Steel forms m anufactured b y the Blaw-Knox Co. were em ployed in lining th e arch and sidewall sections of the tunnel. Form s were furn­

ished the contractors “ knocked dow n” into five p arts; th e arch th e tw o sidewalls, and the two aprons. W hen assembled, th e sections were 5 feet in length, and in tu rn were assembled into a 25-ft. form section D etails of the form construction are shown in Fig. 10. T he co ntracto r on th e east portion of th e tunnel lining work had 14 such 25-ft. sections

LIN IN G O F THE A L V A B. ADAM S TUNNEL 225

/

M il.

opera-

daid 9- nto the ig, etc.,

ending for the

loved furn-

two re 5 on.

or Fig. 10— A n assembled arch and sidewall form.

Fig. 9— 9-inch steel paving forms used for the west end of tunnel invert lining

226 JO U R N A L O F THE AM ERIC AN CONCRETE INSTITUTE November 1946 or 350 lin. ft. of form. T he co ntracto r on th e w est p o rtion h ad 15 25-ft.

sections, or 375 lin. ft.

H atchw ays were provided in th e form s a t 5-ft. in terv als in th e arch and a t 10-ft. intervals ju st below th e spring line.

All forms were wired for 110 volt electric current, w ith wiring enclosed in rigid and flexible conduit. O utlets were provided for lig hts a t 5-ft.

intervals on each side of th e forms and th ere was a convenience o u tlet box on each side a t each end of a 25-ft. form section. R ap id connection of electric cables betw een form s was readily accom plished.

Fig. 11 shows an arch and sidewall form in place. I n th e figure, form aprons are bolted to anchor bolts th a t have been set in th e in v e rt a t 5-ft.

intervals while th e concrete was still plastic. T he needle beam of th e form shifting “ Ju m b o ” has been raised b y four hydraulic jacks to con tact th e arch. Screw jacks are extended to hold sidewall portions of th e form against th e lining. To strip forms, bolts betw een ad jac en t 25-ft. form sections are first removed. In v e rt anchor bolts an d bolts betw een aprons an d sidewall portions are next rem oved an d aprons are raised.

T he screw jacks pull th e apron and sidewall form s inw ard u n til opposite sides are against th e “Jum bo.” T he needle beam is th e n low ered and

Fig. 11— A n arch and sidewall form in place and traveler or “ Jumbo" in position for re.

moval of form.

LIN IN G O F THE A L V A B. ADAM S TUNNEL 227 th e form folds into position for tran sp o rta tio n through other forms in place, to a new location.

Form setting was exactly the reverse of stripping. A form could be stripped, m oved ahead, cleaned, oiled, and reset in less th a n 2 hours.

Form s were left in place a m inim um of 24 hours after concrete placem ent.

A t th e end of placing operations for th e day, a vertical construction jo in t was provided b y placing a wooden bulkhead a t th e end of th e last 25-foot steel form filled during th e day. B ulkheads were left in place for six to eight hours before being stripped.

C O N C R ETE M IX IN G

Procurem ent of a suitable m ixer for use in th e tun nel work presented some problem s because stan d ard mixers of sufficient capacity were too large for a tunn el of this size. I t was necessary, therefore, to remodel th e m ixer fram e and either lower the w ater batching tan k s or provide for w ater batching by m eter. On the east end of th e work, a Ransom e mixer was selected by the contractor and w ater was batched by m eter.

On the west end, a Rex mixer was employed w ith th e w ater batching tanks lowered to provide clearance betw een th e tan k s and tun nel roof.

The small clearance between mixer and tunnel arch and walls can be seen in Fig. 12 and 13. B oth mixers had a capacity of 1 cubic yard.

In feeding the batching w^ater, a portion preceded th e aggregate into th e mixer, the m ain portion was fed w ith the cem ent and aggregate, and the balance was added after aggregate and cement. On being discharged from the mixer, as shown in Fig. 13, concrete fell onto th e pum pcrete charging conveyor for delivery to th e 2-cu. yd. remixing drum of th e pum pcrete machine. T he remixing produced a more uniform concrete and resulted in less delay in placing progress. T he original mixing period of l} ^ m inutes was reduced to 1 m inute because of the remixing.

T R A N S P O R T A T IO N O F FRESH C O N C R ETE

M ovem ent of concrete to forms was accomplished by th e pum pcrete m achines, of which th e horizontal remixer drum was a p art. In both portions of th e tunnel No. 200 pum pcrete m achines pum ped the concrete through 7-in. external diam eter (6% -in. i.d.) steel pipe to th e forms. The pum p on th e western portion of th e lining work was a conventional double-valve m achine. T h a t on th e east portion wras of new design, having a single valve. B oth machines functioned well. T he principal feature of th e single valve m achine was its simplification. I t had fewer working parts, was more quickly repaired, required less servicing, and wTas more easily cleaned a t th e end of a d a y ’s wrork. Some difficulty was encountered in pum ping concrete w ith th e experim ental typ e single

228 JO U R N A L O F THE AM ERICAN CONCRETE INSTITUTE November 1946

Fig. 12 (top)— A Rex mixer was used on the west end of the work. W ater batching tanks were lowered to provide clearance between mixer and tunnel roof.

Fig. 1 3 (bottom)— A Ransome mixer was used on the east end of the work. W ater batching tanks were removed completely to provide clearance and batching performed by meter. ^

LIN IN G O F THE A L V A B. ADAM S TUNNEL 229 valve m achine during early operations, b u t the problems were largely corrected by th e m anufacturer and concrete w ith slum ps as low as 1-in.

were placed w ithout difficulty through 600 ft. of pipe.

The location of the pum pcrete pipe line in tran sp orting in v ert con­

crete to forms differed on the east and west ends. On th e eastern work, th e pipe line was supported on tripods and 10-ft. sections of th e line were removed from th e discharge end as placem ent progressed. On the w estern work, a 300-ft. “ slick” line, th a t is, a 300-foot section of pipe w ithout couplings, was suspended on rollers from the roof of th e tunnel by anchor bars set into th e rock or welded to the steel tunnel supports.

The 300-foot “ slick” and “ strin g ” of equipm ent were moved backw ard as placing progressed. The installations are shown in Figs. 9, 14, and 15.

P L A C IN G

In v e rt concrete, delivered a t the forms on the eastern work from t h e » pipe line located approxim ately in th e center of th e in v ert section (Fig.

14) fell a maximum distance of 4 ft. to th e tunnel floor. General practice allowed concrete to pile up as it flowed from th e pipe line. I t was then shoveled and v ibrated into place. L ittle segregation occurred during the handling of the 1% in. slum p concrete in this m anner b u t care was exercised to avoid over-vibration and m ovem ent by vibration in a horizontal direction was held to a m inimum.

The inv ert form was filled until it was approxim ately level full. A slip-form, which rode on the edges of the in vert form (Fig. 8) was then pulled ahead by a cable attached to an air winch located on th e front of the pum pcrete machine. In tern al ty p e vibrato rs consolidated' th e con­

crete im m ediately ahead of the slip form as it moved forward.

The pum pcrete line on th e west end was 6 to 7 feet above th e tunnel floor and th e chute (Fig. 15) which rode on in vert forms, prevented ex­

cessive uncontrolled drop. Otherwise placing procedure was sim ilar to th a t on th e east end.

Sagging of th e plastic concrete, which was aggravated by vibration, caused some difficulty in filling th e invert adjacent to the sloping longi­

tu din al side forms. F or this reason vibration had to be done with care and th e slum p held a t n o t more th a n ljb-j to 2 in.

In placing arch and sidewall lining a to ta l of approxim ately 150 ft. of pipe was employed. 130 ft. of this pipe was “ flattened-slick,” m ade by welding 7-in. standard pum pcrete pipe, w ithout couplings, and flattened in the vertical direction to 6 in. This was done to provide extra clearance between arch forms and tunnel back which was nom inally about 9 to 12 in. In beginning operations 75 to 100 ft. of forms were set and the

“ slick” passed over the forms a t the crown of the arch (Fig. 16).

230 JO U R N A L O F THE AM ERICAN CONCRETE INSTITUTE November 1946

Fig. 14 (top)— Placement of invert lining on the east end.

Fig. 15 (bottom)— Placement of invert lining on the westend was accomplished by use of a

“ slick" suspended from tunnel roof. Discharge end of "slic k " was supported by traveller running on paving form.

LIN IN G OF THE A L V A B. ADAM S TUNNEL 231

Fig. 16 (top)— Placement of arch and sidewall lining. The pump'line "slick " passes over the arch form.

Fig. 17 (bottom)— Activities at site of arch and sidewall placement.

In placing concrete in th e arch and sidewall forms th e end of the

“ slick” line was set 2 ft. from th e previously form ed construction jo in t.

Two batches of sand-cem ent m o rtar were first pum ped in to th e forms and distributed equally on each side. Concrete of 4 j^-in. slum p was then pum ped into the form until th e area a d jac an t to the previously placed arch and sidewall lining had been filled. The slum p was then reduced to 4 in. and the concrete assum ed a slope of 4 or 5 to 1 in th e sidewalls from the crown of the tunnel to the invert. Pum ping continued u n til th e arch was filled and th e end of the “ slick” buried 5 to 10 ft. T he “ slick”

was th en w ithdraw n 2 to 3 ft. by moving th e “ strin g ” of eq uipm ent b y air winch and cable anchored to th e tra c k behind th e equipm ent. W hen pum p pressure was insufficient, compressed air was used to fill cavities in the arch and hips adjacent to th e arch or to fill th e arch in areas where lagging was in place. Air was supplied to th e “ slick” th ro u g h a lj^ -in . valve located 20 ft. from the discharge end of th e pipe. T he pum pcrete machine did an excellent job and thereby m inim ized th e am o u n t of air

“ slugging” necessary.

In tern al vibration by flexible shaft “ w iggle-tail” vib rators, was p er­

formed where possible, through hatches in the sidewall forms. I t was of special benefit in the consolidation of concrete ad jacent to th e in v ert concrete. Space behind th e forms was constricted, however, an d there was n o t sufficient space for workmen. Therefore, external v ib ratio n was necessary. This was accomplished by chipping ham m ers operated against th e J^-in. skin p late of th e forms, and b y electric v ib rato rs clamped to m em bers of th e forms.

A view of concrete placem ent in arch and sidewall is shown in Fig. 17.

Two internal v ib rato r operators can be seen in th e foreground w ith flexible shafts of th e vibrators extending thro u g h th e hatchw ay s of th e sidewall forms. H atches along th e crown of th e form are open in th e im m ediate foreground and a w orkm an w ith arm extended th ro u g h the th ird hatchw ay is operating th e “ air-slugger” valve. T he inspector with head extended through th e seventh arch hatchw ay is exam ining the concrete being placed in the arch. T he placing forem an also observed placem ent in th is m anner. O ther m en in th e background are operators of th e external v ibrators or chipping ham m ers.

A d a y ’s placem ent of arch and sidewall lining was com pleted again st a vertical wooden bulkhead, a t th e end of a 25-ft. form section. I t was required th a t joints be either vertical or radial. T here was only one d eparture from th e requirem ent for vertical construction joints. In this instance, equipm ent failure resulted in th e abandonm ent of placem ent m idway in a 25-ft. section. A radial jo in t was constructed, w itho ut removing forms, by trowelling the jo in t while concrete was still plastic.

A fter initial set had tak en place, th e jo in t was thoroughly broom ed and 232 JO U R N A L O F THE AM ERIC AN CONCRETE INSTITUTE November 1946