Development of a Design Guide for Ultra Thin Whitetopping (UTW)

Transcription

1 Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW) FNA REPORT November 998 FHWA NJ 2-8 Submtted by Nenad Gucunsk Professor Center for Advanced nfrastructure & Transportaton (CAT) Cvl & Envronmental Engneerng Rutgers, The State Unversty Pscataway, NJ NJDOT Research Project Manager Mr. Ncholas Vtllo n cooperaton wth New Jersey Department of Transportaton Dvson of Research and Technology and U.S. Department of Transportaton Federal Hghway Admnstraton

2 Dsclamer Statement "The contents of ths report reflect the vews of the author(s) who s (are) responsble for the facts and the accuracy of the data presented heren. The contents do not necessarly reflect the offcal vews or polces of the New Jersey Department of Transportaton or the Federal Hghway Admnstraton. Ths report does not consttute a standard, specfcaton, or regulaton." The contents of ths report reflect the vews of the authors, who are responsble for the facts and the accuracy of the nformaton presented heren. Ths document s dssemnated under the sponsorshp of the Department of Transportaton, Unversty Transportaton Centers Program, n the nterest of nformaton exchange. The U.S. Government assumes no lablty for the contents or use thereof.

3 . Report No. 2. Government Accesson No. FHWA Ttle and Subttle Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW) 7. Author(s) Dr. Nenad Gucunsk TECHNCA REPORT STANDARD TTE PAGE 3. Recpent s Catalog No. 5. Report Date November Performng Organzaton Code CAT/Rutgers 8. Performng Organzaton Report No. FHWA Performng Organzaton Name and Address. Work Unt No. New Jersey Department of Transportaton CN 6 Trenton, NJ Sponsorng Agency Name and Address Federal Hghway Admnstraton U.S. Department of Transportaton Washngton, D.C. 5. Supplementary Notes. Contract or Grant No. 3. Type of Report and Perod Covered Fnal Report 3/6/996-3/3/ Sponsorng Agency Code 6. Abstract Concrete overlay of deterorated asphalt pavements (whtetoppng) has been a vable alternatve to mprove the pavement s structural ntegrty for over sx decades. The thckness of such overlay usually exceeds fve nches. n the last few years, however, a newer technology has emerged whch s commonly known as Ultra Thn Whtetoppng (UTW). UTW s a constructon technque, whch nvolves placement of a thnner (than normal) thckness rangng from 2 to 4 nches. The applcaton of UTW has been targeted to restore/rehabltate deterorated asphalt pavements wth fatgue and/or ruttng dstress. Study of UTW was ntated by the constructon of the frst expermental project on an access road to a landfll n ousvlle, Kentucky n 99. Ths rather successful project was complemented by a seres of expermental projects by many state and local agences. There have been more than 7 UTW projects constructed from the early 99 s and many nvestgators publshed papers/artcles on the performance of these expermental projects. As a natural outcome of expermental observatons, a need for a thorough and comprehensve (theoretcal) understandng of UTW system s felt amongst researchers and expermentalsts. n order to gan an nsght nto the contrbuton of the many varables n a UTW pavements system (.e., thckness of UTW, AC and base layers; stffness modul of UTW, AC and base layers; sze of UTW panels; UTW-AC nterface; load transfer; etc.), there have been a few research endeavors. The ntent of ths research study s to dentfy and address mportant factors that contrbute to the performance of the UTW pavement system. t s also the goal of ths research to present an nterm desgn procedure fne tuned by further observaton of UTW pavement systems. 7. Key Words ultra thn whtetoppng, UTW, concrete overlay, deterorated asphalt, restore, rehabltate, fatgue, ruttng 8. Dstrbuton Statement 9. Securty Classf (of ths report) 2. Securty Classf. (of ths page) 2. No of Pages22. Prce Unclassfed Unclassfed 54 Form DOT F 7.7 (8-69)

4 ACKNOWEDGMENT Ths work was supported by the New Jersey Department of Transportaton and New Jersey Concrete and Aggregate Assocaton through the Center for Advanced nfrastructure and Transportaton of Rutgers Unversty. The techncal assstance and fundng support by the organzatons are gratefully acknowledged. SWK-Pavement Engneerng, Prnceton, New Jersey, was a subcontractor on the project, conductng feld testng and developng the desgn procedure, and contrbutng to other phases of the project. n partcular, apprecaton s extended to Drs. Kaz Tabrz and Vahd Ganj of SWK-PE for ths effort. Specal tharlks are extended to Mr. Nck Vtllo of NJDOT and Dr. Al Maher of Rutgers Unversty for ther advce and effort n the development of the desgn gude.

5 DEVEOPMENT OF A DESGN GUDE FOR UTRA THN WHTETOPPNG (UTW) Chapter - ntroducton Pane Number! Chapter 2 - Feld Testng of Route -295 Ramp NDT... Dynamc Cone Penetrometer Vsual Survey... ARAN Pavement Corng Chapter 3 - Fnte Element Analyss and Verfcaton FEM Descrpton Parametrc Study FEM Verfcaton Chapter 4 - Desgn Procedure Stress Due to oad Stress Due to Temperature Desgn Stresses , Fatgue Crteron Traffc Data , Safety Factor Desgn Procedure Desgn Example RWP... Appendx A: Appendx B: Appendx C: Appendx D: Appendx E: Appendx F: Appendx G: The Heavy (Fallng) Weght Deflectometer -295 Ramp UTW Specfcaton Back-Analyzed Deflecton Data (Heavy Weght Deflectometer) Back-Analyzed Deflecton Data (Fallng Weght Deflectometer) Descrpton of Dynamc Cone Penetrometer (DCP) CBR Results From DCP Predcton Equaton Verfcaton

6 Development ofa Desgn Gude for Ultra Thn Whtetomns (UTW) CHAPTER ntroducton New Jersey Department of Transportaton New Jersey Concrete & Aggrevate Assocaton Concrete overlay of deterorated asphalt pavements (whtetoppng) has been a vable alternatve to mprove the pavement s structural ntegrty for over sx decades. The thckness of such overlay usually exceeds fve (5) nches. n the last few years, however, a newer technology has emerged whch s commonly known as Ultra Thn Whtetoppng (UTW). UTW s a constructon technque, whch nvolves placement of a thnner (than normal) thckness rangng from 2 to 4 nches. The appc:aton of UTW has been targeted to restorehehabltate deterorated asphalt pavements wth fatgue andor ruttng dstresses. Study of UTW was ntated by the constructon of the frst expermental project on an access road to a landfll n ousvlle, Kentucky n 99. Ths rather successful project was complemented by a seres of expermental projects by many state and local agences. There have been more than 7 UTW projects constructed from the early 99s (Fgure ) and many nvestgators publshed papers/artcles on the performance of these expermental projects 2*3,4s. As a natural outcome of ex.permenta observatons, a need for a thorough and comprehensve (theoretcal) understandng of UTW system s felt amongst researchers and expermentalsts t. n order to gan an nsght nto the contrbuton of the many varables n a UTW pavement system (.e., thckness of UTW, AC and base layers; stffness modul of UTW, AC and base layers; sze of the UTW panels; UTW-AC nterface; load transfer; etc.), there have been a few research endeavors. The ntent of ths research study s to dentfy and address mportant factors that contrbute to the performance -of the UTW pavement system. t s also the goal of ths research to present an nterm desgn procedure fne tuned by further observaton of UTW pavement systems. Page

7 Development of a Desgn Gude for Ultra Thn Whtetoppng. (UTW) New Jersey Department of Transportaton New Jersey Concrete & Aggregate Assocaton Ths report s dvded nto four chapters. Chapter 2 llustrates the feld testng of a UTW ramp constructed n 994 n New Jersey, usng Heavy Weght Deflectometer (HWD), Fallng Weght Deflectometer (FWD), Dynamc Cone Penetrometer (DCP), vsual survey and pavement cores. The performance of a UTW pavement system s studed usng a 3- Dmensonal Fnte Element Model (FEM). Chapter 3 provdes an n-depth look at the FEM and ts smulaton of traffc loadng, UTW, AC and base layer thcknesses; UTW- AC nterface and ts nfluence on the performance of the pavement system. Fnally, Chapter 4 presents an nterm desgn procedure based on the experences ganed from feld testng and the Fnte Element Model. A hypothetcal desgn example s also presented n ths chapter. Page 2

8 ! Fgure.: Growth of JTW Projects

9 Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW) New Jersey Department of Transportaton New Jersey Concrete & Aegregate Assocaton CHAPTER 2 Feld Testng on Route -295 Ramp n the month of August 994, New Jersey Department of Transportaton (NJDOT) programmed constructon of a UTW on an exstng btumnous ramp connectng Route Northbound to Route 3 Northbound (Fgure 2). Ths was acheved by mllng the dstressed btumnous surface, an average of three (3) nches pror to the placement of UTW. Due to the geometrc lmtatons, UTW was pla.ced n two 9-ft. wde segments wth a jont separatng them. As an expermental project, NJDOT sought to evaluate the performance of three dfferent panel szes. The panel szes were 3 by 3 ; 4 by 4 ; and 6 by 6. The specfcaton used wth ths constructon s presented n Appendx B. n the month of July 997, SWK Pavement Eng,neerng, nc. (SWKPE) was commssoned to manage the feld testng as part of the :research on developng a desgn gude for UTW. n coordnaton wth the Research and Geotechncal Engneerng Bureaus of NJDOT the followng were utlzed: Non-Destructve Testnp: Fallnp Wepht Deflectometer (FWD Heavv Wepht Deflectometer {HWD) and HWD and FWD were utlzed to determne the n-stu stffness of the UTW, AC base and granular bases. Testng across the sawed jonts (between the panels) also allowed for determnaton and rankng of ther load transfer effcency. Reference s made to Appendx A for general descrpton of both HWD/FWD. Backcalculaton analyses of the deflecton data for HWD testng (conducted by SWKPE) yelded reasonable results where those for FWD testng (conducted by others) dd not. t s beleved that the man reason for the successful results usng HWD les n the geophone re-confguraton prct to feld testng. Due to the lmted wdth (or length) of Page 3

10 Development of a Desgn Gude for Ultra Thn WhtetopDng (UTW) New Jersey Department of Transportaton New Jersey Concrete & Aggregate Assocaton ; the UTW panels, HWD geophones were reconfgured accordng to Fgure 3. Usng ths reconfguraton, the maxmum number of geophones were utlzed n 3 by 3 and 4 by 4 slabs and therefore, the stffnesses of the layers could be determned. For example, for a 3 by 3 slab, dl, dz, d3, d4 and d4a were used. f Non-destructve testng was performed on a total of 45 locatons whch conssted of: 29 locatons on 3 by 3 panels, locatons on 4 by 4 panels, and 6 locatons on 6 by 6 panels. Back analyzed deflecton data for HWD testng (by SWK) s presented n Appendx C and that for FWD n Appendx D. Deflecton data was analyzed n order to determne the n-stu layer stffnesses and load transfer capablty of the saw cut jonts.!. Statstcal analyss of HWD back-calculated data yelds smlar UTW stffness for both 3 and 4 slabs (32 Mpa and 35 Mpa, respectvely) but the analyss for the 6 slabs resulted n almost half the above stffness (.e., 8 Mpa). Analyzng the back- calculated data for AC layer reveals that the temperature adjusted stffnesses for 3, 4 and 6 feet slab szes are 9 Mpa, Mpa and. 9 Mpa, respectvely. t may be concluded that the n-stu stffnesses of btumnous base materal are below the normal range of 5-35 Mpa *. To determne and rank load transfer across jonts, the crtera ndcated n Table 2. below were utlzed. Referrng to Appendx C, t s observed that the majorty of jonts exhbt satsfactory condton. t Page 4

11 ~~ Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW New Jersey Department of Transportaton New Jerjey Concrete & Aggregate Assocaton Deflecton crtera A D oad Transfer, 6.2/-6(%) <49.9 oad Transfer, (Mcrons, > normalzed to 7 kpa) Slab (eave) Rotaton (degrees/ normalzed to 7 kpa) ntercept at zero load (mcrons) > >5. > <2. <5., Dynamc Cone Penetrameter (DCP): DCP testng was performed to obtan a contnuous readng of Calforna Bearng Rato (CBR) wth depth. A descrpton of the nstrument and the method of use can be found wth graphcal results of the testng n Appendx E. The thckness of the granular base was used n the back-calculaton of the HWD deflecton data for determnaton of the layer stffnesses. The DCP survey conssted of 3 tests, performed n each core hole. The DCP test numbers correspond to the core numbers (.e., DCP test 4.4 s located at Core 4.4). The detaled result of each DCP test s presented n A.ppendx F. The CBR values summarzed n Table 2 are the n-stu CBR values obtaned n the feld. Page 5

12 Development of a Desgn Gude for Ultra Thn Whtetoppne (UTW) New Jersey Department of Transportaton New Jersey Concrete & Aggregate Assocaton t ocaton Grd Sze Avg. CBR Values x for top 7 nches 4 x 4 85 for the rest Vsual Survey:! ~ A vsual survey of the ramp was carred out n order to determne the areas of sgnfcant dstress. Certan panels were marked for corng. The survey s conducted at walkng speed wth dstresses logged for each pavement area. The scope of the survey ncluded notng the dstresses for each slab. The survey revealed that the major forms of vsual dstress for the pavement structure are crackng and comer breakng. The majorty of these dstresses have been observed to be concentrated n.the area of the constructon jont. The constructon jont was formed n the centerlne of the ramp durng constructon for practcal purposes. Although the dstresses appear to be severe n certan areas, except n one or two cases (n 6 by 6 slabs) the peces are tghtly n place. Partcular comments for each slab szes are as follows:! 3 bv 3 slabs: 3 by 3 slabs have performed the best when compared wth other szes. Areas of major dstresses are n a stretch of 3 feet, 8 feet from the start of the ramp from Random dstresses are also observed but are scattered. Page 6

13 Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW) New Jersey Department of Transportaton New Jersey Concrete & Awregate Assocaton These slabs start approxmately 32 feet from Route -295 where the 3 by 3 slabs end. They are more dstressed than 3 by 3 slabs and the dstresses are concentrated n the vcnty of the constructon jont n the mddle of the ramp. The areas of best performance, measured from -295, are from 32 to 35, 494 to 534 and 59 to 634 where 6 by 6 slabs begn. 6 bv 6 slabs The slabs n ths area appeared to be n worse condton than other slab szes. Crackng and corner breaks, however, are concentrated n the vcnty of the constructon jont. t s to be noted that durng the plannng stage of the constructon, the 6 slabs were predcted to be the worst performng of all slabs. 4 bv 4 slabs: Durng the feld nvestgaton of the -295 ramp, New Jersey Department of Transportaton employed AWN equpment for automatc (vdeo) survey of the pavement and measurement of ts roughness. The data obtaned was not avalable and may be used n conjuncton wth other fndngs n the feld n the future. Pavement Corng: NJDOT forces took a total of ten () pavement cores and the thckness of UTW and AC for each core was recorded. Of the extracted cores only 38 were debonded at the nterface. Other cores showed a strong bond at the nterface -but were broken n AC layer presumably due to corng operaton. Page 7

14 . Development of a Desgn Gude for Ultra Thn Whtetomng (UTW) New Jersey Department of Transportaton New Jersey Concrete & Aggregate Assocaton The average UTW thckness was 3.8 nches wth the thnnest beng 2.9 nches at core locaton 4. (n 4 by 4 secton) and thckest beng 4.6 nches at core locaton 3. (n 3 by 3 secton). Average thckness of 3 by 3 slabs are: 4.2 nches where for 4 by 4 and 6 by 6 are 3.2 nches and 3.65 nches, respectvely. The detaled thckness nformaton s presented n Table 3 below: Table 2.3: Core Results, (A) (B) A la4 Page 8

15 /' /

16 oad Platen / t , 6 Fgure.3: Geophone reconfguraton of Heavy (Falng)Weght Deflectometer for UTW Testng D6 8 D7

17 Development of a Desgn Gude for Ultra Thn Whtetomng (UTW) New Jersey Department of Transportaton New Jersey Concrete g Aezregate Assocaton CHAPTER 3 Fnte Element Analyss and Verfcaton A fnte element model was developed for the analyss of an AC pavement wth UTW. The modelng and analyss was done by SAP2 (Computers and Structures, nc., 997) structural analyss (fnte element) program. The followng sectons contan the descrpton of geometrcal and materal propertes of the fnte element model, loadng condtons, and results of a parametrc study conducted. Fnte Element Model Descrpton The fnte element model of an AC pavement wth UTW s shown n Fg. 3.. n general the model descrbes a four-layer pavement, consstng of the UTW, AC base, granular subbase, and the subgrade. Seven layers of sold elements n the vertcal drecton descrbe ths four-layer pavement. The top two layers represent the UTW layer. The thrd layer s used n the descrpton of the AC-UTW nterface. The followng two layers ndcate the AC layer. Fnally, the bottom two layers represent the subbase. n addton to the sold element layers, the subgrade s descrbed by a set of sprngs. n the plan vew, each of the UTW slabs, and the layers below, are dscretzed nto 36 (6x6) elements, except the central (loadng applcaton) slab that s dscretzed nto 44 ( 2x2) elements. An automated fnte element model generator was developed for pavements wth 3 x3 and 4 x4 UTW slab szes. n the case of a 3 x3 UTW slab model the horzontal dmensons of sold elements are 3 x3 n the central area and 6 x6 elsewhere. n the case of a 4 x4 UTW slab the sold element dmensons are 4 x4 and S x8 nsde and outsde the central area, respectvely. Materals of all layers n the model are descrbed as lnearly elastc and sotropc, except the AC-UTW nterface and UTW slab jonts that are descrbed as ansotropc materals. Page 9

18 Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW) New Jersey Department of Transportaton New Jersey Concrete & Agarenate Assocaton The latter two are descrbed as ansotropc to allow reduced load transfer from the UTW to AC layer due to layer debondng, and from one UTW slab to another due to jont crackng. A detal of an UTW slab jont s shown n Fg Four loadng condtons were nvestgated. The frst loadng case s a temperature gradent n the UTW layer. The temperature gradent s descrbed by a lnearly dstrbuted temperature ncrease between the surface and the bottom of the UTW layer. The second loadng case s a sngle axle load (SA) of 8, bs. appled at a corner of a UTW slab. The thrd and fourth loadng cases are the loadng at a jont and at the mddle of the slab, respectvely. The loaded area n the case of a 3 x3 UTW slab conssts of two 6 x9 areas, spaced 2 one from the other. Each loadng area s equvalent to a sngle tre loadng of 4,5 lbs. n the case of a 4 x4 UTW slab, due to the 4 x4 element dscretzaton, the approxmaton of the prescrbed loadng pattern s gven by two 8 x8 loaded areas, spaced also 2 one from the other. Pror to the development of the fnal fnte element model, the effect of the sze of the model was studed wth objectve to obtan the mnmum sze practcally needed to accurately descrbe the behavor of a much wder pavement. The study was conducted on models havng from 3 to 5 UTW slabs n both horzontal drectons (Fg. 3.3). From the comparson of the stress and dsplacement results for the four loadng cases, t was concluded that 4x4 (Fg. 3.) and 5x5 produce values that do not dffer more than 5%. Ths s llustrated n Fg. 3.4 for deflectons, and maxmum compressve and tensle flexural and vertcal stresses n the UTW slab. Therefore, to acheve sgnfcant computatonal benefts, a 4x4 model was selected for frther analyzes. The 4x4 model has about 9,5 jonts wth about 25, degrees of freedom, approxmately 57 sold elements, and about 9 sprng elements. Page

19 Development of a Desgn Gude for Ultra Thn Whtetoppne (UTW) New Jersey Department of Transportaton New Jersey Concrete & Aggregate Assocaton Parametrc Studv An extensve parametrc study was conducted, wth an objectve to dentfy parameters that sgnfcantly affect the response of an AC pavement wth an UTW overlay. The followng parameters and ther ranges were nvestgated: UTW thckness - 3 to 5 nches AC thckness - 4 to 8 nches AC modulus of elastcty - 88 to,66 ks Subbase modulus of elastcty to 6.8 ks Modulus of subgrade reacton - 45 to 58 pc UTW slab sze - 3 x3 and 4 x4 nterface bondng - from fully bonded to unbonded, and Jont crackng. The combned effect of the UTW and AC thckness and elastc modulus varaton can be convenently descrbed by the correspondng flexural rgdtes of ther slabs. n all cases the followng materal propertes were kept constant: Elastc modulus of UTW - 3,4 ks Posson s coeffcent of UTW -.5 Coeffcent of thermal expanson of UTW -.38* O- PF Posson s coeffcent of AC -.35 Thckness of the subbase - f Posson s coeffcent of the subbase -.35 UTW-AC nterface thckness -.5 nch Jont wdth -.5 nch, and Jont depth - /3 of the UTW slab thckness. Page

20 Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW) New Jersey Department of Transportaton New Jers.ey Concrete & Aggregate Assocaton, The UTW and AC layer thckness, AC thckness, AC stffness, and UTW-AC bondng are the parameters that affect stresses n both UTW and AC the most. Fgures 3.5 to 3.8 llustrate the effect of the thckness of UTW and AC layers on maxmum tensle and compressve stresses n the same layers. The results are for a sngle axle loadng and full bondng between UTW and AC. A satsfactory trend can be observed for both maxmum tensle and compressve stresses. As the thckness of any of the layers ncreases, the maxmum stress decreases. For the range of thcknesses and all the sngle axle loadng condtons used n the analyss, the maxmum tensle stress n UTW vares from about 29 ps for 5 UTW and 8 AC to about 45 ps for 3 UTW and 4 AC. Smlarly, the maxmum compressve stress n UTW vares from about 28 to 242 ps. The maxmum tensle stress n the AC layer vares from about 5 to 48 ps. Both thcknesses have lttle effect on the maxmum stresses n the UTW due to the temperature load. For the F temperature dfference the maxmum tensle stress vares between about 23 and 26 ps, whle the maxmum compressve stress vares between about 8 and 88 ps. Sgnfcantly stronger effect of the UTW and AC layer thckness on the maxmum stress varaton and much hgher stress values are obtaned for fully unbonded condtons. Ths s llustrated n F.gs. 3.9 and 3. for maxmum tensle stresses due to jont sngle axle loadng n UTW and AC layers, respectvely. The maxmum tensle stress n UTW for all sngle axle loadng postons vares from about 5 to 395 ps. A smlar, but much more pronounced trend to that for the bonded case can be observed. The maxmum compressve stress n the UTW vares from about 77 to 445 ps. The maxmum tensle stresses n the AC layer due to the sngle axle loadng vary between 76 and 84 ps. For the +lo F temperature dfference there are no tensle stress n the UTW, whle the maxmum compressve stress n the UTW vares between about 3 and 48 ps. The maxmum tensle stress n the AC due to the temperature gradent vares between about 3 and 3 ps, whle the maxmum compressve stress vares between about 7 and 2 ps. Typcal maxmum stress dstrbutons for a jont sngle axle loadng are shown n Fgs. 3. and 3.2. Page 2

21 Development of a Desgn Gude for Ultra Thn Whtetomng. (UTW) New Jersey Department of Transportaton Xew Jersey Concrete & Aaregate Assocaton j AC modulus affects the magntude of the maxmum stresses n a way smlar to the AC layer thckness. Ths s due to a fact that the real effect s comng from the flexural rgdty of the AC layer, that s lnearly proportonal to the modulus and cubcally proportonal to the thckness. Fgure 3.3 llustrates the effect of varaton of the AC modulus on maxmum compressve and tensle stresses n. UTW and AC. t! Other parameters such as jont crackng, subbase modulus, modulus of subgrade reacton, and the slab sze, had mnor effect on maxmum stresses n both the UTW and AC. Ths s llustrated n Fg. 3.4 for the effect of varaton of the,4c modulus and modulus of the subgrade reacton on maxmum compressve and tensle stresses n UTW and AC. Generally, an ncrease n the modulus of subgrade reacton reduces the maxmum stresses. For the range of subgrade modulus studed, the stress varaton s less than %. Hgher jont crackng (reduced shear transfer) ncreases maxmum stresses, whle the ncrease from 3 x3 to 4 x4 UTW slabs had no effect on maxmum stresses. -. t c, Fnally, because the most crackng on the -295 ramp was observed along the constructon jonts, possble effects of those on maxmum stresses were studed. Two model modfcatons were consdered. The frst modfcaton nvolved complete separaton between UTW slabs along one jont lne. The s.econd modfcaton nvolved, n addton to the frst, a crack propagaton through the AC below the jont lne. The followng observatons can be made from the comparson of the obtaned results. Presence of a constructon jont does not ncrease the maxmum tensle flexural stresses n the UTW due to wheel loadng, n comparson to the jont-free case, however t ncreases by about 2% due to the temperature gradent. Also, t ncreases maxmum stresses n the AC for all loadng condtons by about 25%. As the crack n the AC layer s added, the maxmum stresses n the UTW ncrease by about 25%, n comparson to the jont-free case, and -3% hgher stresses n the AC layer. For an unbound system, the Page 3

22 Development of a Desgn Gude for Ultra Thn WhtetoDpng (UTW) New Jersey Department of Transportaton New Jersey Concrete & Aggregate Assocaton maxmum tensle stresses n UTW and AC ncrease by about 35% and 5%, respectvely. The temperature stresses are also %35 hgher for an unbound system wth cracked AC. From the above observaton, t s concluded that a constructon jont n UTW ncreases the tensle stress n AC. f the AC cracks as well, the stress n AC s relaxed, but the stress n UTW s ncreased. Ths problem requres further study to make more comprehensve conclusons about the effects of constructon jonts on the performance of AC pavements wth an UTW overlay. Fnte Element Model Verfcaton f To verfy the fnte element model, a smple case that the theoretcal results from the Westergaard equaton are avalable s consdered. Westergaard (927) developed closed form equatons for maxmum stresses n a slab restng on an elastc foundaton due to several load condtons. For a load at the center of a slab where the effect of jonts can be neglected, the maxmum flexural stress n the slab can be approxmately expressed as: (3= 3. Where P s the appled load, h s the slab thckness; b ndcates the sze of the resstng secton of the slab; that s b = d.6r2 + h h f r <.724h b=r f r 2.724h 3.2 n whch r s the radus of the appled load. Fnally, s th'e radus of relatve stffness, Page 4

23 Development ofa Desgn Gude for Ultra Thn Whtetoppne (UTW) New Jersey Department of Transportaton New Jersey Concrete & Aggregate Assocaton Eh q- p2)k 3.3 where E and p ndcate the elastc modulus and Posson's rato of the slab respectvely, and k represents the coeffcent of subgrade reacton.! The maxmum tensle stress n a 3-nch thck concrete slab wth an elastc modul of 34 ks and Posson's rato of.5, restng on an elastc foundaton wth a coeffcent of subgrade reacton of 25 pc, under a 2-pound tre locad that has 5 ps ar pressure s calculated as 758 ps. The maxmum tensle stress from thle fnte element model s obtaned as 785 ps. The relatve error s y3.5 whch s bascally due to the converson of the crcular tre load n Westergaard equaton to jont loads n the fnte element model. Page 5

24 Q) c. C - E a

25 Q U c 3 u3

26 Fgure 3.3. Plan vew of models analyzed n the model sze study.

27 Y- n e x3 4x4 Number of 3'x3' slabs n the model 5x5 2 - v - v - - -_ 3x3 4x4 5x5 Number of 3'x3' slabs n the model oxx t - (3 YY c OYY t (322 c Ozz - t v- A- + += Fgure 3.4. Maxmum deflectons and compressve and tensle stresses n UTW as a functon of szeof the model. v

28 r - r- r- r r- r- r- - r- r-- r-- r- - r- Stress, ps to 45 4 to to 4 37 to to to 35 3 to to 3 27 to to 27 Fgure 3.5. Maxmum tensle stresses n UlW as a functon of UTW and AC thcknesses. Corner load. Fully bonded.

29 r r- r-- - r- r- r- r- r- - r- -- Stress, ps to 23 2 to 22 2 to 2 9 to 2 8 to 9 7 to 8 6 to 7 5 to 6 4 to 5 3 to 4 Fgure 3.6. Maxmum compressve stresses n UTW as a functon of UTW and AC thcknesses. Corner load. Fully bonded.

30 Stress, ps 5+ 4 to 5 3 to 4 2 to 3 to 2 to 9 to 8 to 9 7 to 8 6 to 7 5 to 6 Fgure 3.7. Maxmum tensle stresses n AC as a functon of UTW and AC thcknesses. Corner load. Fully bonded.

31 ,! -.., -,.. w Q, W C n >\ 3 - w ([ - a 3 W C m t C 3 m.-. Y- tn m a c.- tn tn 3 2 c. tn E 2 t.- X 3!?! 3 ) u..-

32 Stress, ps to 4 35 to to 35 3 to to 3 25 to to 25 2 to to 2 5 to 75 Fgure 3.9. Maxmum tensle stresses n UTW as a functon of UTW and AC thcknesses. Sngle axle load. Unbonded.

33 ~ Stress, ps 8+ 7 to 8 6 to 7 5 to 6 4 to 5 3 to 4 2 to 3 to 2 to Fgure 3.. Maxmum tensle stresses n AC as a functon of UTW and AC thcknesses. Sngle axle load. Unbonded.

34 Fgure 3.. Frst prncpal stress dstrbuton [psq. 3" UTW, 8"AC. Jont loadng. Unbonded. E+3

35 ! f c

36 ,,2,4,6 AC modulus of elastcty, ks - UTW top UTW bottom AC top AC bottom Fgure 3.3. Effect of AC modulus of elastcty on maxmum compressve flexural stresses n x drecton. Corner loadng, bonded ~ mo - -_ b &- ~- k & k - w---_ k % & &_ k ~ _&_ & h & y Modulus of subgrade reacton, kcf - UTW top UTW bottom AC top AC bottom,8 - Fgure 3.4. Effect of modulus of sugrade reacton on maxmum tensleflexural stresses n x drecton. Corner loadng, bonded.

37 Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW) New Jersey Department of Transportaton New, Jersey Concrete B: Aggregate Assocaton CHAPTER 4 Desgn Procedure: Essental parameters for a desgn procedure are stress levels n the pavement system, fatgue crteron of the materals used, traffc data, and envronmental condtons. The desgn procedure n ths study s based on the stress analyss n the pavement system under a dual tre sngle axle load. Stress Due To oad Snce a fnte element study can be very tme consumng when used as a desgn tool, a seres of equatons s developed to predct the desgn stresses n a UTW pavement system based on the fnte element results of ths study. t was mentoned n the prevous chapter that the maxmum stresses nduced n a concrete slab on an elastc subgrade under a sngle load from the fnte element model matches the Westergaard equaton closely. A UTW system, however, s dfferent from a slab on elastc foundaton due to the exstence of the AC layer and the saw cut jonts. The composte beam concept s used to convert the concrete secton to & equvalent asphalt secton (Fg 4.). N.A. = nc2 +a2 + 2ac 2(nc +a) 4. Bound Secton Unbound Secton Fg. 4.. Composte beam concept for bound and unbound cases. Page 6

38 Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW) New Jersey Department of Transportaton New Jersey Concrete & Aggregate Assocaton where N.A. s the depth of the Neutral axs from the top srface (UTW surface) n nches, c and a are the thckness of concrete (UTW) and asphalt n nches, respectvely, and n s the rato of elastc modulus of concrete to that of the asphalt. 4.2 The secton moment of nerta was determned for both bound and unbound condtons., = nc a nca(a+c) 2 2 4(nc+a) 4.3 and nc3 a3, = The sze of the resstng secton of the slab and the radus of relatve stffness b are obtaned from Eq. 3.2 and 3.3, respectvely, wth h3m beng replaced by the secton moment of nerta. The predcton equaton for maxmum tensle stress n AC for a bound case s developed as 4.5a where C,, C,, and C, are constants obtaned from a least square analyss based on the fnte element results as lsted n Table 4.. The C factor ndcates the contrbuton of the other wheel of the sngle axle (about.) or the nfluence of a constructon jont. Smlarly, the maxmum tensle stresses n UTW for a bound case, n AC for unbound case, and n UTW for unbound case are 4.5b C c, log(-) + c, - 4- c, b h 4.5c Page 7

39 Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW) New Jersey Department of Transportaton New Jersey Concrete & Aggregate Assocaton C b h c, log(-) + c, - + c, 4.Sd The average error of predcted stress values from Eqs. 4.5a to 4.5d are 2.3, 57.5,2.6, and 2.9%, respectvely. The large average error value for Eq. 4.6 s due to the small values of tensle stress n UTW for most of the cases consdered n fnte element study. However, because the small tensle stresses are not of concern for desgn purposes, the equaton can be satsfactory used. The average error for tensle stresses of larger than SO ps s 4.7%. n Appendx G, the stress values from predcton equaton are verfed. Table 4.. Values of constants C, C,, Cr, and C3 n Eqs. 4.5a to 4.5d. Stress Due To Temperature Temperature varaton over the thckness of concrete slabs causes warpng of the slab and ntroduces flexural stresses. The magntude of the warpng stress depends on the temperature dfference between the top and bottom of the slab, the elastc modulus and the coeffcent of thermal expanson of the slab, as well as the slab rgdty. Based on the fnte element results, the followng predcton equaton for the maxmum temperature nduced tensle stress n the slab s developed Page 8

40 Dr~elopment of a Desgn Gude for Ultra Thn WhtetoDpng (UTW) New Jersey Department of Transportaton New Jersey Concrete & Aggregate Assocaton CY = CE,aAT C, - + C, 4.6 [ 5 n whch E, and a are the concrete elastc modulus and coeffcent of thermal expanson respectvely, and AT s the temperature dfference between the top and bottom of the slab. The constant C mplements the effect of a constructon jont, and constants C4 and C5 are obtaned from least square analyss. Table 4.2 shows the values of C, C4, and Cj for bound and unbound cases. The temperature varaton does not ntroduce sgnfcant stresses n AC layer. Table 4.2. Values of coeffcents C, C, and Cs n Eq. 4.6 c Constructon No Constructon c4 Jont Jont Bound.2.o Unbound.35.o c5 Desm Stresses Constructon Jont. The stress values obtaned from Eq. 4.5 nclude the nfluence of the other wheel of a sngle axle through C factor. f there are constructon jonts the desgn stresses should be ncreased to consder the fact that the tre load s not transferred to the other sde of the jont, whle the contrbuton of the other wheel to the tensle stresses should be dropped. The C factor n the case of a constructon jont, based on the fnte element results mentoned n Chapter 3, s 25%, 25%, 5%, and 35% for Eq. 4.5a to 4Sd, respectvely. The tensle stress due to temperature should also be ncreased by %2 f a constructon jont exsts. Table 4.3 summarzes the stress magnfcaton factor for jonts Stress due to Bound Unbound Wheel load (AC) Wheel load (UTW) Temperature (UTW) : Page 9

41 Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW) New Jersey Department of Transportaton New Jersey Concrete g Aggregate Assocaton Temperature Gradent. Durng the day, the UTW surface s warmer than ts bottom casung compressonal flexural stresses to develop at the bottom of the UTW layer. The flextural stresses can be calculated usng Eq The compressonal stress reduces the damage caused by the wheel load. Durng the nght, the reverse stuaton happens and the load damage ncreases. A very conservatve approach s to gnore the reducton of tensle stress durng the day and add temperature-nduced stress to the wheel load stress for the whole traffc. Another approach s to assume that the postve and negatve effect of dfferental temperature durng the day and nght cancel each other,.e. gnore the effect of dfferental temperature. Fatpue Crteron Fatgue equatons, developed by the Asphalt nsttute and Portland Cement Assocaton, are used n the desgn procedure of ths study. The asphalt fatgue crteron s 4.7 where N s the number of load repetton before falure (%lo crackng), E, ndcates asphalt elastc modulus, and (J s the maxmum tensle stress n asphalt. The fatgue crteron for UTW s 4.8 where SR s the rato of tensle stress to the rupture stress of the Portland cement (T SR = - sc concrete. The rupture stress Sl, can be estmated from the concrete elastc modulus (AASHTO 993) 4.9 f Page 2

42 Development of a Desgn Gude for Ultra Thn Whtetoppnq (UTW) 43.5EC New Jersey Department of Transportaton New Jersey Concrete & Aggregate Assocaton s, = n whch E, and Sl, are n ps. t s a good practce to keep SR below 45% so that the UTW can handle unlmted number of ESA s. Traffc Data The traffc data, whch s a combnaton of dfferent vehcles, s converted to an equvalent 8-kps sngle axle to be used n Eqs. 4.7 and 4.8. The converson s based on the fact that the fatgue crteron s a nonlnear functon of desgn stress. t s desrable to let the falure of the asphalt layer govern the desgn, because asphalt should not fal pror to the overlan UTW. Thus, the asphalt fatgue crteron s chosen as the bass for traffc converson. w,, 3.3 = (%) 4. n the above equaton, w8 s the factor to convert a sngle axle weghng WSA to an equvalent 8-kps sngle axle load. Tandem axles weghng double a sngle axle cause more than twce the damage to the pavement than the sngle axle load, because the axles are close to each other and each axle contrbutes to the stress under the other axle. The Eq. 4. for tandem axles changes to 3.3 w,s = (2) 4.2 n whch WTA ndcates the weght of a tandem axle (both axles together) and T s a factor that ndcates how much stress an axle ntroduces underneath the other axle. The tandem factor depends on the confguraton of tres and the radus of the relatve stffness of the pavement system. Based on the nfluence charts for stresses n concrete pavements (Pckett and Ray 95 ) the tandem factor T s roughly.25. t should be mentoned that the 8-kps equvalent factor used n AASHTO 993 s approxmately proportonal to the fourth power of the rato of axle load under queston to Page 2

43 Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW) R= 7 ZR= -.5 New Jersey Department of Transportaton New Jersey Concrete & AggrePate Assocaton 8 kps. The power n the desgn procedure here s 3.3. f detal traffc data s not avalable, one may choose to use the 8-kps equvalency factor based on AASHTO. Safetv Factor t s recommended that the same concept found n AASHTO 993, be used for safety factor (.e. ncrease the number of desgn ESA based on the standard devaton of errors n traffc predcton and pavement performance, and the requred desgn relablty). w - o-z"s" D- w,* 4.3 where So s the overall standard devaton of errors n desgn and ZR s the standard normal devate assocated wth desgn relablty. AASHTO recommends a standard devaton SO of.3 to.4 for rgd pavements and.4 to.5 for flexble pavements. Table 4.4 shows the values of ZR based on the requre desgn relablty R. Desm Procedure The followng UTW desgn procedure s recommended. - Obtan the traffc data for the project and fnd the number of equvalent 8-kps sngle axle load from Eqs. 4.,4.2, and Obtan the elastc modulus and thckness of the exstng asphalt pavement, as well as the coeffcent of subgrade reacton. n-stu testng such as Fallng Weght Deflectometer may be used to obtan modul. Subtract the depth of mllng from the AC thckness. 3- Calculate the allowable tensle stress n AC from Eq Assume a thckness for UTW and fnd the maxmum tensle stress n AC from Eqs. 4.5a and 4.5b for both bond and unbound condtons. 5- Compare the maxmum tensle stress n AC aganst the allowable stress from Step Repeat Steps 4 and 5 untl the allowable stress and maxmum tensle stress are equal. Page 22

44 Development of a Desgn Gude for Ultra Thn WhtetoDpna (UTW) New Jersey Department of Transportaton New Jersev Concrete & Aggregate Assocaton 7- Calculate the maxmum tensle stress n UTW due to both axle load and temperature dfferentals from Eqs. 4Sb, 4Sd, and Obtan the stress rato SR n UTW and determne the maxmum allowable number of load repettons from Eq f the UTW fatgue crteron ndcates a smaller number of ESA's than WD, ncrease the UTW thckness and repeat Steps 4 to 9. - Choose the fnal UTW thckness by comparng bound and unbound desgn process. Page 23!

45 Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW) Desm ExamDle New Jersey Department of Transportaton New Jersey Concrete & Anereeate Assocaton As an example the followng nformaton s assumed avalable for a UTW desgn project: Number of ESA's from traffc data, W~~l,OOO,OOO AC elastc modulus E,=5 ks AC thckness after mllng, a=6 n UTW elastc modulus Ec=5 ks UTW coeffcent of thermal expanson a=.3 8 PF Coeffcent of subgrade reacton k25 pc Tre pressure=8 ps Standard devaton, &=.4 Requred desgn relablty, R=%8 Temperature dfferental=3"f/n Desgn ZF-.8 D - x=2 d = x = 84 ps 2 =6n 3.4~8 Assume c=3 n, h=3+6=9 n (Table 4.4) Equaton 4.3 Equaton 4.7 radus of tre contact area b = J.6~ 62 +9' -.675~ 9 = 5.7 n Equaton 3.2 N.A. = Bound ~ +6' 3 ~ +2x3x6 2(x3 + 6) = 2.25 n3 Unbound, = 42 n3, =4n3 Equatons 4.3 and 4.4 5OOOOOx 42 (-.5')~ 25 = 23.2 n = dp = 5 x 4 7. n Equaton 3.3 (-.5') x 25 Page 24

46 Development of a Desgn Gude for Ultra Thn Whtetoppng (UTW) New Jersey Department of Transportaton New Jersey Concrete & Amregate Assocaton ct=. x 9 x (2.25-9) log(-) - = 79 ps Eq. 4.5a The maxmum tensle stress n AC due to load s less than maxmum tensle stress allowed by Eq Check for the stress n UTW. ct=. x 9 x lo(2.25-3) 42 G, =.(5~~)(3.8~-~)(3~3) log(-) = 78 ps Eq. 4.5b Eq. 4.6 [ 23.2 Total tensle stress for UTW would be 78+74=52 ps. Ths value has to be checked aganst the rupture stress. SR= N=CO The chosen thckness for UTW s satsfactory for bound condton. Try unbound condton: For AC the maxmum tensle stress s cj=. x 9 x 6 2x log(-) = ps ' Eq For UTW the maxmum tensle stress due to load and temperature are ct=. x x9 x 3 2x4 Equaton ~ log(-) - = 553 ps Eq. 4.5~ ut =.(5~~)(3.8~-~)(3~3) [ 23.2 Eq. 4.6 The total stress due to load and temperature would be 643 ps whch leads to a hgh stress rato. Thus, 3 n. of UTW s not satsfactory f no boundng between AC and UTW exsts. However, ths assumpton s not realstc. One may use a lnear nterpolaton between the bounded and unbounded condton. For example, for a 7% boundng, the stress n AC and UTW would be 89 and 299 ps, respectvely. Therefore, a 3.5-n UTW s satsfactory. Page 25

47 Development of a Desgn Gude for Ultra Thn WhtetoDpng (UTW) New Jersey Department of Transportaton New Jersey Concrete & Aggregate Assocaton 295 Ramp As another example the 295 ramp s consdered. From the results obtaned by the Fallng Weght Deflectometer (FWD), the elastc modulus of the asphalt for the frst secton of the panels) s approxmately 28 ks at 68 F. The backcalculated elastc modulus of the UTW s 44 ks. A 3 F-temperature varaton per nch thckness of UTW and a coeffcent of thermal expanson of 3.8 x -6 for UTW s assumed. Core results ndcate the thckness of UTW and AC as 4 and 6.7 nches, respectvely. A bound condton s consdered for ths ramp, because the core results ndcate a good boundng (asphalt was mlled before placng the UTW). Pluggng these values nto Eq. 4Sa, the maxmum tensle stress n AC and UTW s calculated as. x gooo( ) u= -.28g(- ) = 49 ps * x 9 x 5.7 x (2.52-4) c3= -.285lg(-) = 6ps CT =.(4.4 x 6)(3.8x-6)(3 x4) [ The number of allowable 8-kps axles s obtaned from the mnmum of Eqs. 4.7 and 4.8 N = 3,, bound Accordng to NJDOT, the average daly traffc (ADT) for the ramp s 238 wth.8% of heavy trucks and an 8-kps equvalency factor of.536. Thus, the total number of ESA's per day s 238x.8 x.536 = 395. The lfe of the pavement, therefore, s estmated as 76 days for bound condton. At the center of the ramp a constructon jont exsts that developed cracks earler than the ramp tself. Accordng to Table 4.3, the constructon jont ncreases the C factor from. to.25. Ths ncreases AC stress to 57 ps, whch results n,9, allowable ESA's. Thus, the lfe of the pavement adjacent to the constructon jont s estmated as 48 days. Page 26

48 References *. Cole,.W., and Mohsen, J.P., Ultra-Thn Concrete Overlays on Asphalt, Presented at the 993 TAC Annual Conference, Ottawa, Ontaro. 2. Brown, D., Ultra-Thn Whtetoppng Emerges as Rehab Technque, Transportaton Bulder, V7, No., January 995, pp Rsser, R.J., ahue, S.P., Volgt, G.F., and Mack, J., Ultra-Thn Concrete Overlays on Exstng Asphalt Pavement, 5 h nternatonal Conference on Concrete Pavement Desgn and Rehabltaton, V.2, Aprl 993, Purdue Unversty, N., pp Trtsch, S., Whtetoppng, Technque Revves Burgeonng Kansas Thoroughfare, Roads and Brdges, September 995, pp Packard, R.G., UTW Proves ts Worth n Worldwde Tests, Roads and Brdges, July 996, pp Armaghan, J.M., Evaluaton of Ultra-Thn Whtetoppng n Florda, Presented at the 997 TRB Conference, Washngton D. C. 7. Draft Development of Ultra-Thn Whtetoppng Desgn Procedure, Constructon Technology aboratores, nc., January Natonal Hghway nsttute, Technques For Pavement Rehabltaton, US Dept. of Transportaton, FHWA, Sxth Edton, Aprl Pckett, G., Ray, G. K., nfluence Charts for Rgd Pavements, Transactons, ASCE,

49 a APPENDX A THE HEAVY (FANG) WEGHT DEFECTOMETER The Heavy (Fallng) Weght Deflectomaer (HWD) (Fgure A ), s an apparatlls for k-stu, non-destructve testng of pavement structures. Traffc loadng s emulated by applyng load pulses n a controlled manner. Deflectons of the pavement surface are recorded at ncreasng radal dstances kom the load The deflecton response s an ndcator of structural capacty, materal propertes and pavement performance. Features of the WD nclude the followng:. H m Up to 7 non-destructve tests can be completed per hour, each provdng data comparable to that from tral pttng The load s representatve of movng vehcles, resultmg n approprdte pavement response Can be used througho'ut the year, provded the unbound layers are n a unfbzen condton Sutable for th~ck stff pavements due to accurate deflecton measurement n mcrons Type. of Tesp Deflecton Basn Test to evaluate pavement materal propertes for -4sphalt Concrete (AC) and Pavement Cement Concrete (PCC) pavements JontCrack Perfomance Test to measure jondcrack load transfer effcency an3 detect \lods Defecton Sensor Spacng AC Pavements Deflecton testng for AC pavements s performed on the outer wheel track. Se\-en deflecton sensors are spaced at radal &stances of typcally, 2,24, 36.48, 6. and 72 nches (; 35,6-94, 29, 524, and 829 mm as llustrated n Fgure A2. PCC Pavemews For testng of PCC pavements, the test setup used s smlar to that adopted bv the StratePC Hghway Research Propan (SHRP) ong Term Pavement Pedormance (TPP) pro_- for evaluaton of concrete pavements. Jont zest& s conducted by placng the load platen wth a dameter of 3 mm (.Sln) close to the slab corner wth a deflecton sensor on borb sdes of the jont (or crack). Seven sensors deflecton are spaced at radal dstances of typcally -2,O; 2,24, 36,6, and 72 nches (-35:, 35,6,94, -524, and,829 mm). Both "Approach Slab"md "eave Slab" tests can be performed to evaluate rbc. jontlcrack performance (see F,ourz A?). Bask tests are also conducted lo euamte the ntegty of the PCC slabs and to provde remedal dag f necessary. 28 h.

50 pmcularly sutable for nvestgatng a m<de range of pavement types at dfferent constructon stages. Typcal pavements whch can be tested nclude: Conventonal AC or PCC pavements Concrete Block Pavements on bound or unbound foundatons Composte AC/PCC pavements Pavement wth stablzed base Recycled pavements Pavement foundatons and subbase layers Ral road track beds Arfeld and dock pavements _. oadng The magntude of the appled load s recorded. Ths can be adjusted by changng the mass ofthe fallmg weghts or the heght fom whch they are dropped, n order to obtan a contact pressure the pavement surface whch approxmates to the pressure exerted by the types of the vehcles usng the pavement. For tughway pavement testng, the load levels appled are n the range 6, to 6, bs (26.7 to 7.2 kn). For arfeld pavements, load levelsup to 55, bs (244.7 a-rr) can be appled. D& Analyss Usng computer software, the deflecton data s back-calculated to obtan the effectve stfhess of each pavement layer ncludng the subgrade. These n-stu effectve stffnesses are a fundamental measure of the engneerng propertes of the pavement materals. They are used ether n solaton, or combned wth other test data to: Assess the condton of each pavement layer to dentfjr where deteroraton has OCCUT~. Obtan a resdual lfe of the pavement structure usng bo~l aralytcal and equml technques Desgn and recommend strengthenng or remedal measures to ache\te the requred future desgn lfe- Obtan mformaton on the spacng of the prmary transverse slnnkage cracks n a cctlell stablzed bases Obtan nformaton on load transfer and slab support adjacent to jon= and crack n PcC pavements Measure the condton of the equvalent foundaton supportng PCC pavements, enablng an assessment of resdual lfe 29

51 - c r. - Rubber pads (2 No carh rdc) (for dampng of fallmg wcgbl) Wcrthcr rcrsmr cable conocctoo box Typcal Deflecton Bowl U Eso, = A x (Pb/q) Fgure Al: The Heavy (Fallng) Weght Deflectometer 3 Hmd

52 Drecton of Movement Fgure A2: XC Pavement Testng. c Slab Center Testng Approachng Jont Testng Drecton of Movement,- Jontlcrack eavng Jont Testng Fgure A3: PCC Pavement Testng 3

53 APPENDX B Wllam J. Cleary, C.A.E. Executve Drector 9 New Jersey Concrete and Aggregate Assocaton 23 Parkway Avenue Sute *,West Trent New /ersey 8628 (69) 77 - FAX (69) 77-7 NEW JERSEY DEPARTMENT OF TRANSPORTATON DESCRPTON: UTRA THN CONCRETE OVERAY SPECFCATONS Ths work shall consst of the placement of a specal Portland Cement Concrete Surface Course, contanng a number 8 sze coarse aggregate, over an exstng cleaned and mlled flexble pavement. MATERAS: Materals used n ths constructon shall meet the followng requrements: Materals Reaurements Portland Cement 99. Water 99.5 Aggregates 9.3 Ar Entranng Admxture 95. ASTM C-494 Type F Hgh Range Water Reducer 95.2 Synthetc Fbers ASTM C 6 Synthetc fbers shall be added at the plant at a rate of three (3) pounds per cubc yard. At the drecton of the engneer, Type F hgh range water reducng (HRWR) admxture may be used. However, the slump, acheved wth water, shall not exceed three (3) nches before the HRWR admxture s added to the mx. The HRWR admxture s added to the mx at the plant to ncrease the desred workablty durng placement. Type A and Type D water reducers are prohbted because ther combnaton wth Type F water reducers cause undesred retardaton. Admxtures shall be ncorporated nto the concrete mx n accordance wth the manufacturer s recommendatons, at the drecton of the engneer. Only one addton of HRWR wll be permtted at the jobste, unless otherwse approved by the engneer. 32.

54 PROPORTONNG: The contractor shall hrnsh a mx desgn n accordance wth secton 94.2(b) Proportonng and Verfcaton and meetng the followng requrements: Compressve Strength - NOTE ()] ps at 24 hours BOTE ()] ps at 28 days NOTE () - to be determned by Desgn for each project Ar Content: % Water - Cement Rato:.33 mnmum,.38 maxmum EOUPMENT: Equpment shall conform to the requrements of secton SURFACE PREPARATON: The exstng asphalt surface shall be mlled and cleaned n accordance wth sectoj 22.9 Mllng of Btumnous Concrete to the requred depth WOTE (2)] and all edges should be cut vertcal and square. Ths clean, open mlled surface wll provde a postve bond for the portland cement concrete overlay. The mlled out area shall be replaced wth a mnmum of 3 of Ultra Thn Portland Cement Concrete. No bondng agents or slurres are requred. NOTE (2) - To be determned by desgn for each project, and at no tme shall the remanng flexble pavement be less than 2 nches thck. PACNG CONCRETE: The placement of portland cement concrete shall be n accordance wth the applcable provsons of secton 45. Placng Concrete. CONCRETE FNSHNG: The strkng off and fnshng of portland cement concrete shall be n accordance wth the applcable provsons of sectons 45. ntal Strke Off of Concrete and 45.3 Fnal Strke Off, Consoldaton, and Fnshng. JONTS: Jonts shall be constructed n accordance wth secton 45.2 Jonts, and wth the followng: Control jonts shall be cut wth a specal saw that s desgned to cut concrete at or near the ntal set. Sawng shall begn as soon as the concrete can be walked upon. These jonts shall be a mnmum 34 depth and 8 wdth. Sawed control jonts do not need to be sealed. Constructon jonts may be placed at the opton of the contractor. Spacng of the jonts shall be as specfed on the plans. Where solaton jonts are requred, /4 mnmum felt materal shall be placed around all structures such as manholes, nlets, curbng, etc. CURNG: Whte pgmented curng compound shall be appled accordng to, secton 45.4 Curng, and the manufacturer s recommendatons, mmedately arer the last fnshng operaton. When temperatures are expected to drop below freezng, heat retenton curng such as nsulatng blankets, should be used. 33

55 r- - r-- r- r- - r- r- r- r-- APPENDK c Back Analysed Deflecton Data From HWD Staton Normalsed Deflectons Jont Transfer Pavement ayer Stffnesses Crtera Stress dl d2 d3 d4 d5 d6 d7 dl-d2 d2ldl El E2 E3 E4 E5 E6 E7 E8 -- (MW (mcrons) % (MW W c, * 4 (feet) Slabs 4,

56 ~ Staton Stress (MPa) Normalsed Deflectons Jont Transfer Pavement ayer Stffnesses Crtera dl d2 d3 d4 d5 d6 d7 dl-d2 d2/dl El E2 E3 E4 E5 E6 E7 E8 (mcrons) % (MW Statstcal Analvss of 3 lfeetl Slabs Mnmum A 5%le A Medan A 85%rle A Maxmum D Average A StdDevn Statstcal Analyss of 4 (feet) Slabs Maxmum Average StdDevn D 32 B 65 E

57 6 (feet) Slabs

58 ~~ - APPENDX D Staton Stress (MPa) Back Analysed Deflecton Data From TX's FWD Normalsed Deflectons Jont Transfer Pavement ayer Stffnesses dl d2 d3 d4 d5d6d7 dl-d2 d2/dl El E2 E3 E4 E5 E6 E7 E8 ' (mcrons) % (MPa) Crtera 3 lfeetl Slabs

59 Staton Normalsed Deflectons Jont Transfer Pavement ayer Stffnesses Crtera Stress dl d2 d3 d4 d5 ld6d7 dl-d2 d2/dl (MPd (mcrons) % El E2 E3 E4 E5 E6 E7 E8 (MW 6, A 6, A 6, A Statstcal Analvss of 3 (feet Slabs Mnmum A 5%e A Medan A 85%e A Maxmum B Average A StdDevn , E

60 . Sfaton Normalsed Deflectons Jont Transfer Pavement ayer Stffnesses Stress dl ( d2 d3 d4) d5ld6d7 dl-d2 d2dl El ( E2 E3( E4 E5 E6 [ E7 E8 (MP4 (mcrons) % (MW Crtera

61 APPENDX E TE DYNAMC CONE PENETROMETER The Dynamc Cone Penetrometer (DCP) s a very robust nstrument desgned for rapd n-stu measurement of the structural propertes of exstng road pavements constructed wth unbound materals. Contnuous measurements can be made down to a depth of 8mm. or further when an extenson s ftted. Where pavement layers have dfferent strengths the boundares can be dentfed and the thckness of the layers determned. A typcal test takes only a few mnutes and the nstrument therefore provdes a very effcent method of obtanng nformaton whch would normally requre tral pts. Correlatons have been establshed between measuremen& wth the DCP and Calforna Bearng Ratlo (CBR) so that results can be nterpreted and compared wth CBR specfcatons for pavement desgn. Agreement s generally good over most of the range but dfferences are apparent at low values of CBR, especally for fne graned materals. The desgn of the DCP whch has been adopted by the Transport Research aboratory s smlar to that descrbed by Kleyn, Maree and Savage (982) and ncorporates an 8kg weght droppng through a heght of 575mm and a 6 C cone havng a dameter of 2m. n total t weghs 2kg approx. The DCP needs two operators, one to hold the nstrument, one to rase and drop the weght. The nstrument s held vertcally and the weght carefully rased to the handle lmt and then allowed to free fall onto the anvl. t s recommended that a readng should be taken at ncrements of penetraton of about Omm. However, t s usually easer to take a scale readng after a set number of blows. t s therefore necessary to change the number of blows between readngs accordng to the strength of the layer beng penetrated. For good qualty granular bases, readngs every 5 or blows are satsfactory, but for weaker sub-base layers and subgrades, readngs every or 2 blows may be approprate. REFERENCE Kleyn EG, Maree JH and Savage DF (982), "The applcaton of the pavement DCP to determne the bearng propertes and performance of road pavements", Proc. nt. Symp. Bearng Capacty of Roads and Arfelds, Trondhern, Norway.

62 ' DYNAMC CONE PENETROMETER (DCP) Rule 6" 4 Drop 575mm Hole

63 DYNAMC CONE PENETROMETER (DCP) - PENETRATON v ACCUMUATED BOWS h E E v z = a - w z w a ACCUMUATED BOWS

64 r - r r r r r r r r r r r - r r r r r r r -