Improvement of Longitudinal Joints in Asphalt Pavement. Final Report. Iowa Highway Research Board Project HR-215

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2 mprovement of Longtudnal Jonts n Asphalt Pavement Fnal Report owa Hghway Research Board Project HR-215 By Rchard D. Smth Research Techncan Offce of Materals January 1987 Dsclamer The contents of ths report reflect the vews of the author and do not necessarly reflect the offcal vews or polcy of the owa Department 6f Transportaton. Ths report does not consttute a standard, specfcaton or regulaton.

3 Table of Contents Page ntroducton. Locaton... Constructon. Evaluaton.. Conclusons.... Acknowledgement Appendx A

4 PAGE l mprovement of Longtudnal Jonts n Asphalt Pavement ntroducton One sgnfcant beneft of asphalt concrete pavement constructon s that t may be opened to traffc wthn one hour after beng placed. Therefore, road closure and detour are not normally necessary, but only temporary lane closure and control of traffc. Ths one lane constructon, even though desrable n regard to mantanng traffc flow, does pose an addtonal problem. The longtudnal jont at centerlne often becomes a mantenance problem. The objectve of ths research project s to dentfy constructon procedures that wll provde an mproved centerlne jont. Locaton The research was ncorporated by extra work order nto project FR-44-4(26)--2G-39. Ths was a wdenng and asphaltc concrete resurfacng project on owa 44 n Guthre and Dallas Countes, Fgure 1. The resea.rch sectons total approxmately 8. 7 mles between statons n Guthre County and n Dallas County. Constructon The expermental sectons were constructed between July 23 and August 12, The paver was a Blaw-Knox PF-500, the breakdown roller was a Ray-Go Vbratory, the pneumatc tred roller was a Mchgan

5 PAGE 2 Model RW 181 wth a tre pressure of 120 ps, and the fnsh roller was a Huber Model T-1014H. Th~re were eght constructon procedures used wth two sectons (A and B) for each procedure. Secton la, statons to and secton lb, statons to were placed wth a one nch overlap at the centerlne jont as presently descrbed n the constructon manual. Secton 2A, statons to 7+95 and secton 2B, statons to requred a double tack coat on the VE,rtcal face of the prevously placed pass. The frst shot of tack was at the end of the day the frst pass was placed and the second shot was the mornng that the jont was closed. Secton 3A, statons 7+95 to and secton 3B, statons to were placed wthout a horzontal offset between layers; the centerlne jont for the two layers beng vertcal. Secton 4A, statons to and secton 4B, statons to were placed wth the 1:1 edge slope shoe removed from the paver. Ths was done only on the surface course. Secton SA, statons to and secton SB, statons to were placed and compacted usng a revsed rollng procedure. The revsed procedure used on the second lane placed was to roll wthn four nches of the longtudnal jont on the breakdown pass and to overlap on the second pass rather than overlappng on the frst pass as s currently specfed. Secton fa, statons to and secton 6B, statons to called for trmmng 1 1/2 nches from the centerlne edge of the frst lane placed just before the edge was tacked for the

6 . 24.o E3 Exsr"9 'lj>rff ~ 12'-0" { 12'-0" Var.. -+Ex<tng E~rth Sh~-! 3 po --.. _, Slope ~ --- J'~O... ' l Earth Shov!.er Granular Mate<al.! Gron.olor Moterol ~ au,h'.~.'"'"'~~ude~, DESGN QUANTTES TEM Swtlo(.e Cov 8.ru co... no Tod Coot RATE 140!1>1./<u. h. 140 Jtn./q1. ft / 4- ytl.!l" t Stc1on! VOLUME 7; 11 To.., To" Gel.(!) G'"""lor Motottcl f 1.00 To ~ lsr eted let 2 epplcoto..,s. \%! (tf; oled f.,. 1 st>o.,.lc:loo: : ORGNAL. PAVEMENT 1 US/~' re.-7c.t:_,:::;.~~~f; t 4>!6:" "3~A.~.C _;}c':"-c...~ CU;>:;~ 19;"'TYPE-"B" ASPHALT CEMENT c-6n-crete SURFACE course LJ - -. TYPE "8" ASPHALT CEMEN-T -1 lv2" ( Averoge Thckness} _CONCRETE.BNDER COURSE : TYPCAL CROSS SECTON ASPHALT CEMENT CONCRETE RESURFACNG ROAD DENT. STATON TO STATON la. M :'.! '5. :>:) 5-R %. X! la. M ;;.. 52_~5. U 11;... 12_ 1s 2:Q.o. 19. )) ta. 44 JQuaton: Sta. 2CQ'tl9.CO-Sta. 0-Xl. J tz. 41 o-oo. ro.&'>'.rll la. M" 5A+r:1 ron ~~22.Xl.. 44 >0-~.00 F-.,.,.J>.,d lop 1hcJJ.. c;a~,.,.,,...,;,_.,~,,... - t P' tftot tl o "'0'-''"'".. o' ~..,.;~:." ;P" ) 0..., Cftd.;.,,..,,.. o '<>wo':>.. < :>"!.s~. S cloo,. OV b.- "'od;;.,,g OU :' fl<h,.ff,,. ~ 1uou!tj, 0~ 1n ol <!) ' ": >'>C.C.. q t..!~. lo Obvl<l~lfd!;S!'"l C' ~--~ (<J<v ond Ston<' -.,!oocl >!o1" 0QQ,11onol re<:,,;_...,.,,1.,.,.,,.g.., '"Olf lfllf<tole" ;.,,...,, Fgure 1: Project FR-44-4(26)--2G-39 Guthre County "Cl e;,.,, w

7 PAGE 4 second pass. The method of trmmng was not specfed but t was assumed t would be by sawng or usng a rollng Colter. Nether method was used. An attempt was made to do the trmmng wth a motor patrol blade but a straght edge could not be obtaned. The edge of the bucket on a skd-type loader was sharpened and used to trm the edge. mmedately followng the trmmng, the mat was rolled to assure bond wth the underlyng layer. The edge was tack coated the same day a.nd agan pror to closng the longtudnal jont. Secton 7A, statons 1S4+40 to and secton 7B, statons to agan had the centerlne edge trmmed as n sectons 6A and 6B but wth the revsed rollng pattern used n sectons SA and SB, that s lappng over the longtudnal jont on the second roller pass nstead of the frst. Secton 8A, statons to and 8B, statons to had the longtudnal jont sealed by the pneumatc tred roller on the fnal pass. The project was paved from east to west and the jont was normally closed from the south sde. Evaluaton Cores were drlled from each secton August ls, 1980, about three nches left and rght of the longtudnal jont and from the quarterpont of each lane. The denstes of each core and the average for each locaton per longtudnal jont procedure are ncluded n Table 1.

8 PAGE 5 TABLE HR-215 MPROVEMENT OF LONGTUDNAL JONTS N ASPHALT PAVEMENT Secton Sta. Densty S-15-SO Procedure No... pt. CL CL.. pt Rt. Rt. Lt. Lt. la Present lb constructon 1 AV procedure - 1" overlap 2A S Tack coat 2B vertcal face 2 AV between passes 3A Delete 3B transverse 3 AV offsets 4A Delete 1:1 4B slope shoe 4 AV on edge 5A lS 2.37 Roll wthn 4" of CL SB on breakdown, overlap 5 AV CL on 2nd pass 6A Trm 1st pass ±_ll:" 6B 3S before 2nd pass tack. 6 AV Standard roll pattern. Surface course only. 7A S s B Same trm as 6, rollng 7 AV procedure as 5. SA Use pneumatc roller SB on jont on fnal pass. s AV

9 PAGE 6 The core denstes show that denstes at centerlne are less than those at the quarter ponts. Ths dfference n densty could be elmnated by usng a full wdth paver whch would requre closng the road. Vsual nspectons were made the frst three years after constructon. At four, fve, and sx years, measurement of centerlne crackng was done wth the roadmeter car usng the dstance counters. One counter was used for cracked areas and the other counter for areas not cracked. The total of the two counters was the denomnator when determnng the percentage of centerlne crackng for each secton. The totals for correspondng sectons were added to determne percentages for each procedure. The only procedure to rank the same when comparng crackng and densty s No. 4 (delete the 1:1 slope shoe on the edge). Ths procedure had the hghest average densty and also had the least crackng through The other sectons dd not correlate well when comparng densty to crackng. All but procedures 1, 2, and 3 had cracked 100% of ther length by November 1986, and they were cracked 96.1%,. 92.7%, and 92.5% respectvely. Each of those procedures had one secton that was 100% cracked. The percentage of crackng by secton and year s lsted n Table along wth the denstes near the centerlne that were determned after constructon n After 1984, all procedures exhbted a very steep slope n the rate of crackng (Fgure 2).

10 PAGE 7 TABLE TABULATON OF CRACKNG AND CENTERLNE DENSTY % Cracked CL Densty Secton Rt Lt la B A+B A B l A+B A B A+B A B A+B SA B A+B A " ~ D <:t.l. " OJ.J..LVV,. V.... "t.:::... u ~ nc c 'nn n " OA " oc A+B A B A+B BA B A+B Conclusons None of the procedures used on ths project succeeded n preventng a longtudnal crack along centerlne. The method provdng the best performance for four years after constructon was removal of the 1:1 slope shoe from the paver when placng the surface course. Ths method had 9.0% cracked after four years and 100% cracked after sx years of servce.

11 . 1 z 0 ~ " ' 0' CL ~ " 0' ' u; z ' w; 0 N f- w 0 w < " " < " u (.~ z "w z" B" 'O Q) -"' u "' s.. u t-o ~ ~ - Dx o~ 0 " M d z 1 oo 1 -" : 1T:---: :-, ! l ' 40 [ :-.' l Procedure!, -:~~!..!... 1 _1,_! ' Present constructon proccdu:e - l" overl,1p 2 Tuck coat VerL:.cal fucc bct\.jeen passes De lr,~ te transverse:! offsets Delete l: l slope shoe on edge Roll wthn \" of CL on breakdown, ovcr~ap CL on 2nd pass Trm lst pass +1~ before 2nd pas tack. Standard roll pattern. Surface course only. 7 Sarne trr;o us 6, :col. lng procedure as 5. 8 use pneumatc roller on jont on fnal pass. 1--! ' :! '..; t -~ - 1 ; ::!..~!- 1. : :.:- r: -r..: -! 1,! ' ; : :. 301-l-h ;-,-- -t- -,---c : : 1., f-j+ 1 1 t--~.,...!+jl 1 j 1 1,. r, ; 1 1 '.. t +l r ' '... ' ' ' ' ' 1 ' '. :1:.l" t.-t.. :~: r-r r:. -~-1-~-1.. :.!-.: ::.t r.:r,j''.,l,_, - '-~T ~j,! ' r!Jr1 ll1j '.., ; ;! : :.-.!! T. r..:. T~-- ' 'l.. :! : '. '! _:._f_....j.:._ t.,;-~-l t -- 1~ t--j-...;_. - ' 1 :!! j : ;! l 1 j ' 1! ' t , ;!. ;,,; (.!-- t l -.j ' Q;D, '' 1 ' 1! 1 l 1 l#,.. lo ll". --T 7 T''. -,... '80 '' 1.1?17\)..,.-, l',.,..,, nr11.r-:-r ' ' '! '!,_;_,_ f 1 j ' ~ 1 1 1,- ' ' ' ' -l. ' (.. 1 1! ' ' 1 - -! r n!-1 1. :! _ _1 j 1 : : ' :! ''["' J,;,' ' ' ('! ' ' ~ '!.. _,. l ' ' ' '. --..,----:- :,,., :!. -!+ 1' : :! :'_: ~:! ' ' ' : : ' '! : :,!_ j :,, '< ' ' : l..,- ' ' ' l -'-4--1-H -.', -t r-....' : ~. ' ': ',,'. : 1..' ' : : '.,..,..,... +L, ; ''"'t L. -l". Fgure 2:. : '. : : j, 1 :! ~~~-;...,-!! ' 1 \!.' ': '!' ',1 t!"' ' ' '.. ',, ' '!., 1- ~...;.J~. ' r )! J ' 1. '...,., "f rt:; :~;-,-1, ' ', ' ' J,,j_ _j : 1.. ~-- - '. l -.. l! j', 1.,. ' ' : r--f-1~-l-l....j...! 1 ' t. r '! 1 : F r-r ' 1. :: ; 1'. 1 :. J!-;--l--f)- ' 1 :! l : :!, -:-!--:-- ~""""t-~ -; Rate PAGE 8 "".. 1 "\ "1 r- ;. fttt - 11, 1.J. -T;2' -2 "?.,-- l :-+1.!!! ' L~:.. h-r :.L ' '!.j..,_f - +1 ; ',.j!! ] ' :. ' : T '86 ; :J_, \ ' j : : ;.:j.'.j.,... _).,. l ' '. ;_;J..,, : r ; _J~.: ).., ' :,. ~. ~ --~.- : -J : r!!-- ~L '..1 t!, '. 1--}+"1 ' ' 1' ' '. :...,,...,11.. ' 1; :tj ' '!'' ; r ++.:...1 : : ' ;,..,,.:_ r 1 1 '.!.l :-:ll,! ~...!...'.-.j ; L.,... J.._ :.)..! ' : ; l 1 1',,_.J_J

12 PAGE 9 The areas placed wth a one nch overlap as presently descrbed n the constructon manual had 27.3% of the jont cracked after four years and 96.1% cracked after sx years of servce. Between four and sx years of servce the rate of crackng for all methods used on ths project was about the same. Overall, there was no one method that out performed the others n ths project. Acknowledgement The cooperaton of the contractor, Hennngsen Constructon Company, s apprecated, as s the help of personnel from the Creston Constructon Offce, especally Larry Delaney, Project Supervsor for hs help n supplyng constructon nformaton ncluded n ths report.

13 Appendx A Paae 10 OWA OEPARTMEH OF TRANSPORTATON HGHWAY DVSON 2/10/86 CONSTRUCTON MANUAL 8.43 GUDELNE STRNGS AND EDGE ALGNMENT True edge algnment controls the correct lap at the longtudnal jont. f there s no lap, the jont wll lack densty and ravelng 1 1ll occur. An excessve lap produces an objectonable wde scab of mxture on the surface next to the jont, that has to be removed wth hand tools to obtan an acceptable appearance. An ntended lap of one nch-wth a varance of one-half.nch each way has been observed to produce correct longtudnal jont constructon wth mnmum effort. f these close varances are to be mantaned, the adjacent lane has to be constructed wth true edge algnment.... One Df the nspector's dutes n obtanng true edge algnment s to make frequent measurements to nsure that the gudelne strng has been correctly set and mantaned. The nals used to secure the gudelne strng shall be at ntervals close enough to elmnate chords on curves and other rregulartes caused by wnd, etc. Gudelne strngs placed on all two-lane pavements except old concrete should be located by measurng from redhead nals whch have been placed on the centerlne by nstrume~t partes. The spreadng of the lower layer wll cover the redheads. For succ"eedng layers, the gude ne strng should therefore be located by measurng from the exposed nals that were used to hold the strng for the lower layers. When resurfacng old concrete pavements that are only t.wo lanes n wdth, the contractors-have been permtted to locate the gudelne strngs on the shoulders along the outer edges. Ths s done by measurng out from one of the pavement edges at ntervals of approxmately 500 feet, then tghtenng the strng and usng ntermedate nals to secure the strng. To nsure that parallel algnment s used for the adjacent lane, the gudelne strng for that lane shall be located by measurng across the pavement from the nals used to secure the frst lne. To prepare a smooth locaton on the shoulder for the gudelne strng, the specfcatons requre that the grass shall be closely mowed for a wdth of approxmately 18 nches. On curves for all surfaces, a suffcent number of nals shall be used to permt the fnshng machne to follow the lne exactly wthout producng objectonable chords on the curved edge algnment. The fnshng machne operator shall follow the guclel ne strng exactly. f the machne (JOes off the lne for any rt'1son, t c,hojll lw ldj11stcd bad onto the lne mmedately. t s ncorrect to smooth oul the edge algn111ent ly comng back onto the lne gradually. Ths results n long stretches where ncorrect lap at the longtudnal jont wll occur. Also when batch trucks bump the fnshng machnes off the lne on curves, the movement s usually down the slope of the curve. f the machne s brought back on the lne gradually, an objectonable, long, straght chord wll result n what s supposed to be the curved edge algnment. 8-25

14 Paae 11 OWA DEPARTMENT OF TRANSPORTATON HGHWAY DVSON 2/10/86 CONSTRUCTON t'anual n. '14 When automatc screed controls are used, the short jont matchng shoe shall not be permtted except when placng a sngle lft only, wth a tl1ckness nf ll.nches or less, or for placement- n conjuncton wth heater scarfcaton work: When the lower layers are constructed, the specfed 30 foot sk devce shall be used for jont matchng on each layer. The short jont matchng shoes produce jonts wth smoother appearances than the 30 foot sk devces. Hewever, they do not contrbute toward constructon of a smoother rdng surface. The 30 foot sk devce does.,_smo,oth l ong tu d na l jonts are very mportant for surface l aye1's and the short jont matchng shoes may be used when surface layers are spread. Careful adherence to the nspecton procedures descrbed n Secton 8.43 wll nsure true edge algnment whch s essental for the correct constructon of longtudnal jonts PRME AND TACK COATS USNG EMULSONS P", General lack coats usng emulsons are requred pror to October 1. Dluton of emulson s requred ( non-unform tack applcatons are experenced. SS-1, SS-lH, CSS-1, and CSS-lH. grades are specfed. 8. For Dluton Dlute at 1:1 rato,.e., 1 gallon emulson to 1 gallon water. C. Applcaton Rate Double the usual specfcaton rates of applcaton normally used for RC-70 or MC-70. Ex., 0.03 to 0.05 Gal./S.Y. ncreased to 0.06 to 0.10 Gal./S.Y. dlute emulson. D. Sample for Com~lance Sample the emu son at the spray bar of the dstrbutor wth the bar valve n a crculatng poston. E. 0easurement for Pay 1'11e"net gallons of undluted emulson. F Note: Undluted emulson must contan a mnmum of 57% asphalt resdue. Dluted emulson must therefore contan a mnmum of 28.5% resdue. Settlement of Dluted Emulsons ASs.urance sample reports receved on a number of projects ndcate tha-'t dlute emulsons are not meetng the mnmum resdue requrements. A revew of ths problem wth producers n the state ndcates that the dluton rate s beng carefully controlled and that the resdue of the orgnal emulson s hgher than the mnmum requred. 8-27