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; CONSTRUCTING EXPERIMENTAL CONCRETE PAVEMENT IN INDIANA I , I
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For sale by the Superintendent of Documents, Washington, D. c. - - - - - - - - - - - - - see page 2 of cover for prices ‘ I I
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‘ 1 I 5111 ___—_____——_—_.—————————————-\ _ E‘
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11 .
1111“ P U BLIC ROADS ’ I I A foumallll‘
‘ 5. 11 13 .‘ . ;~
1 151: g Highway Research '
. ' 1‘ I ;
1 1 1 1_ Issued by the - Reported by
= . 1 1 ‘1 1 ' 1‘ E F]
11 11 1 1 . FEDERAL WORKS AGENCY . 1111311311111),
;‘1=1 1 1 PUBLIC ROADS ADMINISTRATION ‘3, sign 121,119.51
1 I 1 “ ' S.
. 1 11 _1 11 D. M. BEACH, Editor _ 1111361116111 0
11111 1 1 1 Volume 20, No. II January I94(] 1 51m exists a:
111 :1 M 1 eeeeeee
”111: 1 I‘ 1 The reports of research published in this magazine are necessarily qualified hy the conditions of the tests from which the data are ohtaimd. ‘ decreaSeElnf:
1 11 11 1 Whenever it is deemed possible to do so, generalizations are drawn from the results of the tests; and, unless this is done. the conclusions .‘ xiincilfothé
1‘ 1 1 ‘1 1 1 formulated must he considered as speczfically pertinent only to described conditions. .~ lengths of 31
.- 11 11 1 I ___._. ; indicated tl
' 1131‘ 1 11 .; that are 03
11111 5'11 ” short slab 1e
3 .1111; - e, A avem
. «‘ ‘1'1 ': p
1 1131 11 In This Issue 1; 0.1st 001,111
1 1.11 '1 ; _ p... :-; will fulfill 1:1
1 1111;1111 Experiments With Continuous Reinforcement in Concrete Pavements . . . . . . . 205 ’ Iransfelr 110a;
' 11i15111 forexcu 1n
.1. I1 1 1 . - ,
1 '1; 111.11 The Cost of Curing Concrete Pavements With Cotton Mats . . . . . . . . . . 2I5 .. manner, ha'
1,1. ‘ z 11 . . . . . There exi
1 13; 1 1 Cost of Operating Rural-Mail-Carrier Motor Vehicles . . . . . . . . . . . . 2I7 toward inc]
1 1.. mile of; PE
‘ 1: 1 111 1 ‘ _——___.————————————————__——— engineering
. 3 11111: 1 1 _ . 1 eliectlve de
j1 111 1 THE PUBLIC ROADS ADMINISTRATION - - - - - - - - Willard Budding, Washington, D, C, 7 11011, Elle 1.
. 1 I1. _ 1 1 _ _ _ - some lines
1 -1 11 ‘11 1 REGIONAL HEADQUARTERS - - - - . - - - . - - - Federal Bu11d1ng. CIVIC Center. San Franc1sc01Calil. J for joints t
’ 1 1111.1“ 1 2 impaetw—th
I 11“ 1 v Irguments
11 «1111 DISTRICT OFFICES . 10%qu
1‘51 1111.: ment in so
1. l1 11 1 DISTRICT No. I. Oregon. Washington. and Montana. DISTRICT No. 8. Alalzama. Georgia. Florida, Mississippi. and Tennessee. ‘ lnlle aftel.‘ I
. lll 1 I: 1 11 Post Office Building. Portland. Oreg. Post Office Building. Montgomery. Ala. lglznt‘slfit 1n
.11.111.1 _ . ‘ . .11S0 Vlou
:_ . 111 l 1 DISTRICT NO- 2- California. Ar 120“» and Nevada. DISTRICT No. 9. Connecticut. Maine. Massachusetts. New Hampshire. New . iated With
11 1 1I 11 Federal Building. Civic Center. San Francisco. Calif. jersey. New York. Rhode Island. and Vermont. l' llllS thougl
111 1'1 1 DISTRICT No. 3. Colorado. New Mexico. and Wyoming. 505 PM 0mm Building'Mbany'N'l' ‘1 years, the 1
1 1 ‘1. 1.11 “New CuewmhoueeeDenveer‘eb- DISTRICT No.10. Delaware, Maryland. Ohio. Pennsylvania, and District Experien
i 1‘ 1.1 l ' 11 DISTRICT No. 4. Minnesota. North Dakota, South Dakota. and Wisconsin. Of Columbia. . . , . concrete pt
1 1 1' 1 11 ' ‘ 907 Post Office Buildin St Paul Minn W‘lla‘d Bu‘ld‘“g'wa‘1““g‘°"'D‘c i ‘ ' t 1
1 j' 1; ; 1; 11 g‘ ' ' ' DISTRICT No. ii. Alaska. _: 101“ Se P a“
1 1 1‘ g 1: DISTRICT No. 5. Iowa. Kansas. Missouri, and Nebraska. Room 419, Federal and Territorial Building, Juneau.Alasks , Will‘plng St]
I 1 1. :1 7H U. S. Courthouse. Kansas City, Mo. DISTRICT N ‘2 I ‘ h d U h . lack of prOV
,. 11.1.1 ; . . d t. .' '
1‘- 11111 1.131; DISTRICT No. 6. Arkansas. Louisiana. Oklahoma. and Texas. 0 a 0 an a Federal Building. Ogden.UtIlh : 11Vh11e 131.1651
1 II11111 1"; Room 502. United States Courthouse. Fort Worth. Tex. DISTRICT N 14 N h C l S h C l V d W I l (I?) abserlgu
;; 111.»; 1" 1 ; . _ 1 . . t ' . t ' . ' ' ' . es ns ru
1 1 1i 1 . l DISTRICT No. 7. lllinms. Indiana, Kentucky. and Michigan. 0 Ilirginiairo ina 011 31’0 Ina irginia an . that th: 16:;
1 1 1 1‘ ‘1 ;; South Chicago Post Office Building. Chicago. Ill. Montgomery Building. Spartanburg.S-C- ’
. . 1,111“ '1. ; I lhrOUgh th‘
‘11 :1 _——"———————“—_‘_—_‘——_—-’ ;‘. The poss
1 1 1 1.111111.‘ ; Because of the necessarily limited edition of this publication it is impossible to distribute it free to any person or institution other . 13%: frequen
I1 ‘1 II . . . . . . . . . . - ~
1:1 11 1111:} than State and county oflicrals actually engaged in planning or constructing public highways, instructors in highway engineering. 1 l Ough th
1 1 11 . . . . .. .. . . . merit ham
1 11 1 11 :11 and periodicals upon an exchange bans. At the present time additions to the free mailing list can be made only as vacanCies occUI- although a
1 1' 1; 3 Those desiring to obtain PUBLIC ROADS can do so by sending $I per year (foreign subscription $I .50 . or I0 cents per single copy. 0
1 1 _ oncrete
; ; 71 1; 111‘; '1 .~ (I to the Superintendent of Documents, United States Government Printin Office, Washin ton, D. C. ‘ perature Cl
1 ;_ 1.; 1 1 g g ;
. 1111; 1 i1 .. ________—_—_————————/ -: ficoncrete
i . 1‘11-I ' e
1 11.1.1 I1 11 CERTIFICATE: By direction of the Commissioner of Public Roads. the matter contained herein is published as administrative information \mperatu}
' .1111 '1;1 and is required for the proper transaction of the public business. lPaDel‘ presen
31; 11111 1 11 - ‘3 Board, Deceinbe
1' 1111 Z 198848~40-
‘ 1‘ ‘l‘ ll‘i ‘ 1;
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.111 ”.1111; ; .
‘ 1111i 1151: . 1
1|: l11‘1 ‘ . _ . W J"

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53;. TTE I.
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' ' 'I III
EXPERIMENTS WITH CONTINUOUS w
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5‘1 . I: I?
I r~ REINFORCEMENT IN CONCRETE - - II II
. 3 IT ll
'° PAVEMENTS III
{1th , I: TT'I
_ iii, ReportEd by EARL C. SUTHERLAND, Associate Highway Engineer, Public Roads Administration, and SANFORD W. BENHAM, Research Engineer. II II
Indiana Highway Commxssxon. . . ITT I
.1 NTHE FIELD 0f concrete pavement design, there is volume changes tend to occur. ~Wlien the slab at— ITTII‘
If; T16 [probably no subject that has provoked more discus— tempts to contract or to expand, it must overcome the ,I ITI
x. sion than that of the proper spacmg for transverse resistance to deformation of the subgrade with which it ITT i '
' joints. Today, after more than {10 years of concrete is in contact. This is the source of the direct tensile TTT. I:
if: _ pavement construction, a WlCle' divergence of opinion and compressive stresses in a transverse section of the I II‘
“940 = still exists as to the proper spacmg to use. pavement. In addition to direct stress, temperature I II
T The general trend for some years has been toward and moisture differentials down through the slab IT. III
lainédT “decreased slab lengths. Gradually the distance 'be— develop periodically and these create bending stresses II III
I , ,‘3 tween joints has been reduced until at the present time because of the restraint to warping that ex1sts in slabs 12' T
'um'tt most of the concrete pavement 1s being laid with slab of appreciable length. The summation of the stresses I E I
. T}. T: lengths of 30 feet or less. Theory and experiment have that are caused by these conditions of temperature and IT I,
4%; 1 indicated that for satisfactory control of the stresses of moisture, either alone or in combination with the II II
, not are caused by restrained temperature warping a stresses that are caused by vehicle wheel loads, may II III
,«short slab length is necessary. exceed the tensile strength of the concrete and cause a T: TIT
3; A pavement designed with short slab lengths obvi- rupture of the pavement slab. I II
'ously contains numerous joints. Joint designs that The introduction of longitudinal steel reinforcement TITTTI
,‘ will fulfill the requirements for flexibility, for ability to into a concrete pavement Will not prevent the formation I 2:.
transfer load and effectively to control load stress, and of transverse cracks under the stress conditions just IETIITI
v 'for excluding water and foreign matter in a satisfactory described. However, the presence of steel will have an I IITIT
;¢ ~Q‘Tmanner, have not yet been developed. important effect upon the character and distribution of I T I'iTI
. 1 There exists an understandable feeling that the trend the cracking that occurs and upon the structural II
T 3 toward increasing the number of joints required per integrity of the pavement and it is this action that II IT
S. : mile of pavement is a mistake, although present possibly may prove to be of advantage in reducing the , TITIITI
; I? engineering knowledge indicates this to be the most number of constructed transverse joints required in T..TTT
[effective design. The cost, the difficulties of installa- concrete pavements. ' IT ITIIII
DC: tion, the leakage of surface water to the subgrade I TTTTII
.‘T- " (sometimes with very harmful results), the tendency REINFORCING STEEL “1’13;ng qulfizgwnivcn THE CHARACTER TITITIT
"cath- for joints to be or to become rough spots producing , _ TI ITTTTT
. TI ; impact—these and other criticisms are advanced as Moderate amounts of_ steel reinforcement in concrete II III
arguments against the use of short slabs and frequent under tensmn add relatively httle t0 the tehShe res1st- II IIII
TI, joints. If it were possible to design a concrete pave— ance 0f the SBCthh PTIOI' t0 the tlme that rupture 0f II "’TITT
, 57. ': ment in such a manner that it would be continuous th‘? concrete OCCUTS- Thus, m a concrete pavement, T.-‘ I“
nnemi,‘ I mile aft-er mile, or even if it were possible to space the 1t 15 to be expected that the first crack W111 appear at I I?
We; joints at intervals of 1,000 feet or 500 feet or even less, about the same place and under about the same condi- I, I;‘
. ‘I _ it is obvious that many of the problems that are assoc— tIOhS 0f stress m thh a remforced and an unremforced I III
.TTTeTN” : ioted with frequent joints woujd disappear. Although slab, other conditions being the same. As soon as I VIII
:myN.Y- 5 this thought has intrigued the minds of engineers for rupture 0f the concrete 900135: however, the 0011029306 I IT
T j LIT years, the solution to the problem has not been found. section that was most highly stressed 15 relieved 1111' I I
Disfiicl’ ' Experience has shown what is to be expected in plain mediately Of all stress Whlle any bonded steel that ‘
“on.“ " Popcrete pavements that are laid continuously or with crosses the ruptured 530t10h suddenly assumes a much . I TfTI
’ , 10111133 placed at infrequent intervals. Contraction and greater burden than before. , I I
“In”, {I I warping stresses cause frequent transVerse cracks and , The stresses caused by subgrade reSistance are 031“ .I’
‘T. lock of provision for expansion may resultin“blow-ups”. “ed across the rupture by the steel and transferred , T I
emu-ii . While these troubles have not always been experienced gradually back to the concrete through the. bond I I I
’ , §. Ito a serious degree, in general, those interested in the between the two materials. The distance in which the III I
m! w T coustruction and maintenance of highways have felt full amount of stress is transferred back to the concrete III I
surest ‘ that the effort to control cracking and other troubles 15 dependent dh‘eCtlY upon the length 0f the-section IT
5: _ thrOugh the use of joints was worthwhile. and the degree of bond between the two materials and . IT I I
a; I The possibilities of pavement slab designs in which indirectly upon the amount 0f steel. The result 13 IT, I II
m other ‘ the frequency of constructed transverse joints is reduced that 111 long slabs reinforced Wlth _relatively large I I I j?
neeriné. , through the use of continuous, bonded-steel reinforce— amounts of long1tud1nal_ steel, additional transverse ITIIT I
S occuiiT- I ment have never been very thoroughly explored, cracks may be expected in close prox1mity to the‘first I I T,
:3 , although a limited amount of information is available. plane 0f rupture: The distance between the pomts at I III I
le COPY; E Concrete changes in volume when subjected to tem- which the stress in the concrete section reaches a magni- ITTTITTI
; perature changes or to changes in its moisture content. tude Shih‘heht to cause rupture W111 depend primarily ' '- I II I
-—"ET: 5 Aconcrete road slab is subject to severe changes in both upon the amount 0f steel that transfers stress 30,1055 ~- I T I I
.- temperature and moisture content and relatively large the ruptured concrete. sectIOH, although for a given (T TIJI
T‘ Wted at th \Iin t nth Ann 1 M tin fthe r51 hwa Research percentage Of lonthUmefl‘ steel a certain slab length ls . INT ,
_ Board, December 8.1939} A e 99 “a 96 g 0 g 3’ necessary to develop the effect that has been described. ; I; II
_" , 198848~4o——1 , 205 I’TIITT
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1 ‘1”1 ji~ , v | The Columbia Pike experimenta] J“

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1‘15: Mime 1 13316;“? at the present tlme ch1efiy becafise E11133: 1s 0f of the secti

i i n , 1 “a 10“ 0f the type of cracking that 00 ”We stretgth 0f
11; l ‘1 s “‘t ' ' pig/«’97 “5 performance that may be expected in ours and the sectionS-

1; [1 t c ,5 1 , ,_ e;‘« taming relatively large amounts of 1 paYesznts con. In the 13
i i ‘ fww» “Ki 1 fOIif‘fiment' ongltUdmal rein- of transvers
‘ 1H ‘ he" i 7 cw {xi-$1 e most heavily reinforced s ' ‘ ncrete sec

1 g . 1 1 . d“; ~ii * ' whom 15 3 GO '

P 1 1. t .. 5:2»; I, iii, 033??“ 114 thmsmarter—inch rounio (1:13:11ng for 560m“

‘11 1 . ,. ~ :zgjffN large 111111133232; Sgggfdfiétecrosls lfs 18—f00t wi d thine: Eggs???

1 111 1 F 1 _ - j ' "-5 Cracksfdevelpped in the dent22i 3173asr1tmoefd’thtilsansvs'r Se cofitmuousl;

1'11 1 1 IGURE -‘—PRESENT APPEARANCE OF A HE W soon a ter t e pavement was laid $661011 SEC/lions th

1 1 1 1 1 SECTION OF THE COLUMBIA PIKE EXPERIM £313: gitiiffifin service, these. cracks are still closedAfEEEIC-l 18 Years of slabs. This

ii i ‘ i ,i ' "if”:»‘v‘-7""“77“‘L”‘-,.r - .W I spalllng OI‘ dlslntegration has OCCurred i1] th Very 'htltle reinforced .
1 s 1 2 : , ‘ ; .. ' Ageneral View of th' ‘ eir Vlcmlty Vith small

1} 1 {1 1 . . :~ , .. the 1 f 15 section of pavement taken W'thi' ‘

11 ~11" 1 _ 1 . - 1.1 1 1 ast ew1months IS shown in fiaure 1 F' 1 11 11.11 gener:

1 :1“ ‘1 1 , 1 “ " 'if'l Slows two v1ews of the pavement ant a t 7 . lgureg dismtegrati

3‘ 3;: i ' ‘ ' ,; ' " . ,. It Will be observed that the general 37'9ch crack, inwhich th

f ‘ 11: 1 j 1, , - ...__..,.. ' ' l .. i . . 4 $901710? 0f PaVement is still good and tlfotntfitlon of 131115 ' by the sub;

l Wt 1 _ ‘ ,. 1 . integrity of the pavement h b a ‘ 6_Structum] able values

‘ (ii; i t T , :zi, '7 . ' though figure 1 indicates (lisstafiigsmgimtamed' AL In the 2C

i i ii i 3.3;: 1 . I between transverse cracks, actually it 812 Several feet amount Of

' 5“: ii - c" that haVe deV610ped to an extent 3 fiiO'WS only those grade ““7515

Iii 3‘ ' »_ y 11, the eye 0f the maintenance crew lidCient to Catch 0f the cone
‘1 1 {iii in" verse cracks c b ‘ dltlonal trans- anumber o
1 Jill‘] 11 ,1 ,. V31“ tho h h an 6 found by 01086 examination 1 -

‘4 ’F-“d I ’ 1 ug ‘3 ey are 50 fine that they are difficult t , a- have devel

1 11111 1 , , . , .1 ..,a:~: ev’el‘lhm (ajrflatively qlose—up View such as that in fighrieg’ T119526 crac

. 5215111 (‘1 3‘.’_P,%:r 1 , lon e o umbia Pike experiment indicates that in ' Spam-g or

' i affilr: 77"”, tiég‘hme‘ g concrete pavement Slab the Presence f l ' a amok In On
1 Midi i «it J3 *e“”§§"45~ *W ' fight» large amounts 0f longitudinal steel will gregfl rei atively %-1nch rich
'1 i1, ;1 7 ‘77,? ‘iw‘zf’s, j%%%’?: E; 375131 Ibunllibler of transverse cracks but that chsenggzie - 'l‘hese e3
1 ‘1 | .i ‘3 "6:51;; g: “~61; ’ ,a« U t e e d tightly closed (if the slab length is nott S iected mi 10
; ‘- '.“».“i 1 , 34.3”” area ) and further that over :1 Ion ' d - 0° mtegmtlon
l1 i it”; . . 2"”. ‘,‘ 7:5; I” 1 "1'17 Struotural break-down need be tg Perlo 0f tlme I10 temperatur
1 1 1 11:! ch _.,, ,3, . , -_ .' V 1: also that the 'an lplpated. It Shows conditions
1 1 1111 1. .7 1,, , w: ., . , ,1: merit increasesptrlfgedl‘ci 0f longitudinal steel reinforcei The behz
is rtl‘i ~ . v " ”e ‘ “ - a; 15 we between Open cracks. experiment
1 ' 3 ‘ g 1 1 ' im" ‘5 3 3}: REINFORCEMENT FOU 59W“. ‘
l I 5 1 : ’ ’ 1 ”and, .1»: ND T0 REDUC ions -
1 1 1 11 11 1 1 , ,fi AND NEAR ENDS OEEnghcgiligslN SHORT SUBS 3111,1310” to
LY: I t , ,1 . » ., i 1 r 1 iese sti
: 1, w 1 1 .. w Several years after the 001 ~ ' - -
¢ 1 1 1 . i ,1 _ 1 c . umbia Pike 8 the same t1
11.1 11111 . FIgIURE 2.-—TYPICAL CRACK IN A HEAVILY anponc S -. bUflt, a study of curmg methods for co ectigns were understand

1 91,1“ AngROIisT§E COLUMBIA PIKE EXPERIMENTAL 1331133111?” ments was undertaken at the Arli 1; ngre e pave- . ments and
Ni 1111 MENT LOWFSAE:G%F0§E§::§E. UPPER, SURFACE or PE}: Eggn}, Virginia, utilizing test sectionrslgofo 1113151; Xperimeiét 1 mm d on t
1 ’ ‘ ' * - - eet long 2 feet wide - n 90m” e
it; 1 - . - .’ . i and 6 Inches thi 1. Western:
1 111.1 extleliiltsi 3:511]? fvsfiils Obslerved and studied to a limited 33331133210336}; t~h {has dStEdY’ a number of reii’lfmfifi Stlrless1 conzii
; , 11 . . . 0 9631‘ yresearches of the Pub ‘ ' ' - me u. e or the P111“ Use of 1 ' ‘ W ee load

. 111 éggiiijgztf?! Elbe significant features of Whicfiojvciifi igggltiznoileri‘rrfgrmatifiln on certain coliiditions (iiitaiiuiigfi Changess

1 1, rie 1 _ in e ' - tio b 1
n -, ll Th - y C 1 ~ eXperlmental Sectlons 011 the 1115 BtW
; '; v e earliest of th ‘ ' ' ~ Oumbm Plke- The d ' - t

:1 '11 I golumbia Pike expegisrtiieiilé‘lStgiitégfngs£1152719f tthe behavlor of the various £533:anihldlauslggsgutfimn and iigsiiitlift}

1 2111111 ounty, Va. This avem 3/ 1 ring on experiments have been given- t . e curing 1 corn -.
ii ”Tm built in 1921 ' p ent, .1/4 mfles 10mg. was The amo t f - m W-O pu‘thhedrel")1”ts-H ‘ er” am
1 115m :1 , and included Various Slab thi 1 , . 1111 0 steel in the reinforced sections was 111g Wlth t‘
_1 11141 cross—sectlonal designs and . cmesses, varied from a very light weld d f b - - culati 0‘ th
' a I'ri'li‘ The ma'o 1t f :. reinforcement des1gns round deform d b ' e _a no to two %-1nch no

4"; W 1 1 r1 Y o the reinforced sections ar 20 f I e ars (m the 24411011 Width) There Of these 00

1. 111211111 011g and the ‘Lm l) f . , G 0 BGli were, as Stated a n b ‘ ' . l I

111.1, A t 01111 0 reinforcement m th ’ um 61‘ of plain concret t 1 n order
11-; 1 i varied from a hghf, weld d f b - em was and these may be used f0 - - 6 sec 10-113 ‘ Irz db
is * W?“ A bl' h .e a 1‘10 ‘00 a heavy bar mat fore d 1' r comparison “nth the rein- I i e 37-“

1 1 11111, P11 ls ed report deSCI'Ibes the d' ‘ - 9, sectlons. Some of the 200f t - by Studies
1: 1 111 all: 1 ment at the time it / COD ltlon of the pave- duplicated by secti‘ h _ 09 - sections were P b1'

11: {111mg . d - _ W33 2}2 years Old,2 The details f 81 b _ 2 OHS t at Were dlvlded into five u .10 R05

1 11111 1 ceign of the various sections of O - a S' 0’ 30’ 40: 50 and 60 feet 1 I tenswe er

‘_’1 g’tf» 1 haracteristi f h pavement and the In the steel and ' th’ 011g. The stresses i T ' ‘1
l ,1 i 1 : Ei‘h CS 0 t e subgrade are given in th' ’ in e concrete caused b th b 1‘ d9 hls gener
eji 3?“; 9 type of crackin ' . .18 report. reelstance alone robab y e 511 'g a an 1
; 1 | 1:11 11 1« steel reinforcement iiilaciiscifslégf‘i m r(Elation to the slabs up to 60 feetJin lengthwmlli‘ii tfi0t2g308feXOeSSIVe m of dtli‘eiaisni/‘L

,1 111111 1 Papers.3 4 111 tWO subsequent howlearer, the stresses caused‘by the Subgrefigi sect-$111; of this pap
.1 :1 :E‘1i11111,1 —.—-—.—— wou exceed the 140' - 6815 ‘ it

. e wit 1_ 'Remforcmg dth . _ u imate tensile e GCtS 0f 1

at»; ”S:eereefitttifiiérfietEater:teetersnewsreteiravemems. concrete: over a considerable part of 132%; 35311331? \—
11 1 11 11 1 . iu ina LeelandTransv 1 C k ——-—_ 7 ‘ 0fth ‘ 101
1, 11!, )1 WA '1‘ Goldbeck,PUBLrp ROADS, 1.6.N 1 We “‘0 95111 Concrete Roads, 5T ts . eHighway
: i ii iii: 1 cahcgggégggeflhgtifiti: asilgillgeln WY’g‘eller ath'in’ll‘gllfgiilgsflgroceedings Ameri- Ngljfltise ygigfiggggzgunég M.eth0ds’ by J. T. Pauls, PUBLIC ROADS’ VOL 7' waggégizgigv 9"
‘1 1 l 111 :1 1 ROADS, volflo, N’gnlgl’z géfl‘gggillggbb} L. W. Teller and H. L. Boslcy, PUBLIC 3- D’Eaiiv’isstgigsz
i1. t‘hi‘}

1 l»; l

 , . :1 1 1
. 11
~ . 111
l ‘ l
, it
0.11 January1940 PUBLIC ROADS 207 1111
a E 1111 l
of of the sections, and would probably exceed the tensile behavior and the observed structural action of the sev- 1 1111
me strength of the steel 1n the more lightly reinforced eral Jomt des1gns that were included in the design of 1’11
the sections. _ _ the test sections.9 The slab behavior was determined, 111121
on- In the 13 years Since the sections were built, a number in general, by strain measurements. 1 11111” 1
1111 of transverse cracks have formed in each of the plain 1 1,1111
concrete sections and in the central portion of the 200- r: 22;,1. ,5": , 1 1',‘_:;1
311g foot sections that are continuously reinforced with the 71:11 '1‘? f1 .1 ”1'1; 11 11
led larger amounts of bonded steel. There has been a '1: gr it," 1_ 14111;
A negligible amount of cracking near the ends of the 1 ” ”ff-'15:] 3,": ‘11‘.1{11
arse continuously reinforced sections and m the reinforced ~ , ”1:1; 3;" -’ ‘11'1
ion sections that were divided by joints into shorter g; . . 1' . r, .5 j '55,; '3 1 7 f] 1 5 11’
1 0f slabs. This condition obtains in both the sections 7- 'j .5515, ~ . 11 l 1
ttle reinforced with large amounts and those reinforced " V , ’5 E : , ’ ' ‘3 ‘3.“
ity. with small amounts of steel. 1 .1 ~ ~‘ 11"; f in .. . 1 11
.th In general, no appreciable amount of cracking or . . j 1., ,_ ..~, 11111
e 2 disintegration has occurred in the reinforced sections A '1 .1 if! \I ” ' . ,. ; . .' 1, .111‘
10k, in which the stresses in the steel and concrete, caused ‘ " " ' . ’ ' ' ' , "? 3 ‘ " 1
this ‘ by the subgrade reelstance, have been held to i‘eason- FIGURE 3.—TYPICAL FINE CRACK IN A HEAVILY REINFORCED 11111
m1] able values. SLAB CONSTRUCTED IN THE ARLINGTON CURING TESTS, 13 1111111.
A]. In the 2f00—f010t section? containing a relatively large YEARS AFTER CONSTRUCTION “ 11-11
feet amount 0 stee , in w iCI t e stresses caused b sub— =11
lose grade resistance have exceeded the tensile sti‘rength “SEARCHES SHOW ‘MPO‘QEQI‘LESESF CONTROLLING WARPING ‘1‘
1tch of the concrete, but not the elastic limit of the steel, ‘1 :11
ms anumber of very fine, closely spaced transverse cracks One of the important results of these researches has {.1111
al- ‘ have developed in the central part of the sections. been development of an appreciation of the importance 1131
see, These cracks have remained closed and little or no of the warping stresses that are present in concrete 5111111
'e2. spalling or disintegration has developed. A typical pavements at times when large temperature differen— 11
II a crack in one of the reinforced sections containing two tials are present, stresses that in certain regions of the 11H“
17er 11-inch deformed bars is shown in figure 3. slab area combine with load stresses to cause critical 1
ease These experimental sections have never been sub- stress conditions. To control warping stresses, the re- 1‘1 1 .
Lcks jected to loads of any kind so that the cracking and dis- straint that produces them must be controlled and this 1; :
too integration that has developed has been caused by the can be accomplished practically by limiting the prin- 1111‘.
1n0 temperature and moisture variations and by other cipal dimensions of the slab. The significance of these . 1 1
)ws, conditions of exposure. combined stresses as they affect the structural design of E 11 '
me The behavior of the reinforced sections in the curing a pavement has been very completely discussed in a 1111
experiments at Arlington tended to confirm the ob- recent paper by E. F. Kelley.10 ‘3
servations made on the Columbia Pike sections adding Recognizing on the one hand the experimental evi— ll: ‘
LABS support to the theory that has been outlined. dence that short slabs are necessary for the control of 1;} 11’
1 These studies and others that were in progress about warping and consequently of combined stress and on the : 11 .1
were the same time emphasized the need for a more thorough other hand the practical objections to the introduction 1:131
ave- understanding of the structural action of concrete pave- of more JOints in concrete pavements, the _Public Roads 11 11111
cent . merits and for a number of years attention was concen- Administration and the Indiana _State Highway Com— [ 1'1: 111.:
'rete trated on this problem. _ _ missmn in_l9§6 deCIded to investigate more thoroughly 211 111
’ In Westergaard developed his important analyses of the the pos51bilit1es of longitudinal steel reinforcement as a 1 1:11
rce d stress conditions in pavement slabs under the action of means for increasmg the slab length of concrete pave- .1‘ 11
ning wheel loads7 and under the influence of temperature ments. _ _ ‘ 1 1 ‘1 11
had Changes.8 The first showed for the first time the rela- Consideration of the problem indicated that the in- 1.111
the hens between load, deflection, and stress for an elas- formation des1red could best be obtained through the . 1‘11
and tie slab of uniform thickness on an elastic support, deal- construction of special sections of reinforced. pavement 1 1111
nine: mg With the three critical pomts, a free edge, a free located on a highway in serVice and on this basis an 11‘
ts“ ‘ corner, and an mterior pornt. The second paper, deal- extens1ve research pI‘OJGCt was planned. Arrange- "113
“1115 mg with temperature effects, presented means for cal- ments were then made for the construction .of the 1 :11
111011 culating the stresses caused by warping restraint. Both deSired experimental reinforced sections in Indiana as 1 1 1
. of these contributions are of fundamental si ificance. part of a regular Federal Aid pI‘OJBCt. The State and “1
here . gn . . . . . 111
tions 1 In order to study experimentally the relations ana— the Administration cooperated in the selection of a 1‘1.
rein- 1 lyzed by Westergaard and to supplement those analyses suitable location, the. adJustment of the experimental 1 ‘1
were by studies of other_than_ uniform cross sections, the sections to_ the location, the construction of the sec- 1
five PUbllc Roads. Administration built and subjected to 111- tions, and in the program of measurements and obser— :1‘
esses 1 tGIIISWe experiment a series of full—size pavement slabs. vations. _ 11 111
rrade - This general research covered a period of several years _The pavement was constructed on atranscontmental 11 '_
ie in and was diVided into a number ofparts. Those parts highway west of Indianapolis. This location was 1
)lOllS. 0f the mvestlgatlon that are Pertlnent t0 the sub] Bet W211 Design of Concrete Pavements, by L. W. Teller and Earl C.
*ancé Of this paper have been reported and cover the observed Sutherland: . , , . . ‘1'
.J effects Of tem eratur and moistur ariatio S 0 slab Pt. 2. Observed Effects ofVariationSin Temperatureand Mmstureon the Size, 1 1
the p e 6 V 11 II Shiiplefi, 311113 gtrggvggjggpiliggsof Concrete Pavement Slabs, PUBLIC ROADS, 11 1
5ngtll E “Itgomputation of Stresses in Concrete Roads, by H. M. Westergaard, Proceedings lat-4, ’ A_ Stiidy of thaSti-uctural Action of Several Types of Transverse and 1
Strisgéghwacv Research Board, pt. I, 1925. . _ Longitudinal J cint DeSIgns, PUBLIC ROADS, vol. 17, Nos. 7 and 8, Septem- 1 .
. W