TRANSPORTA TJON RESEARCH RECORD 1307 221 Case Studies in Rehabilitation Strategy Development MICHAEL I. DARTER AND KATHLEEN T. HALL The performance and rehabilitation of jointed concrete pave- ments was recently investigated in a major national field study. Among the products of the research were detailed guidelines prepared to i;ssist practicing engineers in determining when res- toration was likely to be cost-effective, and when a structural overlay was required. The data base for this project included 95 ections of joint reinforced con.crete pavement and joint plain concrete pavement in their first performance period. Thirteen of these sections were selected for use as case studies in rehabili- tation strategy development. The sections were selected to cover the range of four major climatic zone of the United tates, a well as a range of pavement condition from good co poor (as- ses ed on the basis of cracking, joint deterioration, joinr faulting, pumping, and serviceability). The EXPEAR computer program was used to evaluate the current condition of each pavement section, predict its future condition without rehabilitation, and compare the predicted performance and co !-effectiveness of var- ious rehabiJitation strategies. The case studies demonstrated that restoration is the most cost-effective alternative for pavements that are structurally adequate and do not have concrete durability problems. Restoration is a rehabilitation strategy that involves a com- bination of methods for repairing distress, improving ride quality, and extending pavement life without a structural ov- erlay. Restoration techniques for jointed concrete pavements include the following: 1. Full-depth repair of joints, cracks, and corner breaks; 2. Partial-depth repair of spalls; 3. Grinding to remove faults and studded tire ruts and to improve surface friction; 4. Grooving to improve surface friction; 5. Subsealing to fill voids under slab corners; 6. Slabjacking to improve the pavement's longitudinal profile; 7. Load transfer restoration at joints and cracks; 8. Joint resealing; 9. Crack sealing; 10. Subdrainage improvement; and 11. Shoulder improvement. Concrete pavement restoration typically involves a com- bination of several of these techniques. Over the past 25 years, many states have gained experience with restoration, and de- tailed information on design, construction, and performance of various restoration techniques is available from a variety of sources. (1-4) M. I. Darter, ERES Consultants, Inc ., 8 Dunlap Court, Savoy, Ill. 61874. K. T. Hall, University of Illinois at Urbana-Champaign, 1206 Newmark Lab, 205 N. Mathews, Urbana, Ill. 61801. Little guidance is available, however, to assist the practicing engineer in determining whether a particular pavement is a good candidate for restoration, or whether another rehabil- itation strategy would be more appropriate. Restoration has been applied to many pavements which were really in need of structural improvement. The result, even if the restoration is well designed and well constructed, is short rehabilitation life, high life cycle costs, and diminished confidence in the effectiveness of restoration among engineers and highway users. It is possible for practicing engineers to assess the appropri- ateness of restoration, using information available about the design and condition of a particular pavement section, re- habilitation performance prediction models, and rehabilita- tion cost data. The EXPEAR computer program can be used for the purpose of comparing rehabilitation strategies for 13 pavement projects across the United States and representing a wide range of pavement conditions. PAVEMENT PERFORMANCE AND REHABILITATION NEEDS Maintenance Versus Restoration The success of restoration depends on good design and con- struction, but it also depends on application of restoration at the appropriate time in the performance life of a pavement. The earliest time that restoration should be done is relatively easy to identify. Early in a pavement's life, its condition is excellent and its rate of deterioration is slow. For several years, routine or preventative maintenance is more cost- effective than any rehabilitation strategy. Restoration is gen- erally not warranted until distresses such as cracking, faulting, and joint spalling have developed to the point that they detract from the pavement's serviceability. When annual mainte- nance costs equal or exceed the equivalent annual cost of restoration, the restoration work is justified. Restoration Versus Resurfacing It is more difficult to identify the latest point in the pavement's life at which restoration is likely to be cost-effective, i.e., the point at which the pavement has carried so much traffic and sustained so much structural damage that an overlay is needed. It is conceivable that resurfacing may be done before this point and be more cost-effective than restoration, primarily because of the ability of overlays to reduce deflections and slow deterioration in the slab. Early resurfacing seldom oc-
13
Embed
Case Studies in Rehabilitation Strategy Developmentonlinepubs.trb.org › Onlinepubs › trr › 1991 › 1307 › 1307-025.pdf · TRANSPORTA TJON RESEARCH RECORD 1307 221 Case Studies
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
TRANSPORTA TJON RESEARCH RECORD 1307 221
Case Studies in Rehabilitation Strategy Development
MICHAEL I. DARTER AND KATHLEEN T. HALL
The performance and rehabilitation of jointed concrete pavements was recently investigated in a major national field study. Among the products of the research were detailed guidelines prepared to i;ssist practicing engineers in determining when restoration was likely to be cost-effective, and when a structural overlay was required. The data base for this project included 95 ections of joint reinforced con.crete pavement and joint plain
concrete pavement in their first performance period. Thirteen of these sections were selected for use as case studies in rehabilitation strategy development. The sections were selected to cover the range of four major climatic zone of the United tates, a well as a range of pavement condition from good co poor (asses ed on the basis of cracking, joint deterioration, joinr faulting, pumping, and serviceability). The EXPEAR computer program was used to evaluate the current condition of each pavement section, predict its future condition without rehabilitation, and compare the predicted performance and co !-effectiveness of various rehabiJitation strategies. The case studies demonstrated that restoration is the most cost-effective alternative for pavements that are structurally adequate and do not have concrete durability problems.
Restoration is a rehabilitation strategy that involves a combination of methods for repairing distress, improving ride quality, and extending pavement life without a structural overlay. Restoration techniques for jointed concrete pavements include the following:
1. Full-depth repair of joints, cracks, and corner breaks; 2. Partial-depth repair of spalls; 3. Grinding to remove faults and studded tire ruts and to
improve surface friction; 4. Grooving to improve surface friction; 5. Subsealing to fill voids under slab corners; 6. Slabjacking to improve the pavement's longitudinal
profile; 7. Load transfer restoration at joints and cracks; 8. Joint resealing; 9. Crack sealing;
10. Subdrainage improvement; and 11. Shoulder improvement.
Concrete pavement restoration typically involves a combination of several of these techniques. Over the past 25 years, many states have gained experience with restoration, and detailed information on design, construction, and performance of various restoration techniques is available from a variety of sources. (1-4)
M. I. Darter, ERES Consultants, Inc., 8 Dunlap Court, Savoy, Ill. 61874. K. T. Hall, University of Illinois at Urbana-Champaign, 1206 Newmark Lab, 205 N. Mathews, Urbana, Ill. 61801.
Little guidance is available, however, to assist the practicing engineer in determining whether a particular pavement is a good candidate for restoration, or whether another rehabilitation strategy would be more appropriate. Restoration has been applied to many pavements which were really in need of structural improvement. The result, even if the restoration is well designed and well constructed, is short rehabilitation life, high life cycle costs, and diminished confidence in the effectiveness of restoration among engineers and highway users. It is possible for practicing engineers to assess the appropriateness of restoration, using information available about the design and condition of a particular pavement section, rehabilitation performance prediction models, and rehabilitation cost data. The EXPEAR computer program can be used for the purpose of comparing rehabilitation strategies for 13 pavement projects across the United States and representing a wide range of pavement conditions.
PAVEMENT PERFORMANCE AND REHABILITATION NEEDS
Maintenance Versus Restoration
The success of restoration depends on good design and construction, but it also depends on application of restoration at the appropriate time in the performance life of a pavement. The earliest time that restoration should be done is relatively easy to identify. Early in a pavement's life, its condition is excellent and its rate of deterioration is slow. For several years, routine or preventative maintenance is more costeffective than any rehabilitation strategy. Restoration is generally not warranted until distresses such as cracking, faulting, and joint spalling have developed to the point that they detract from the pavement's serviceability. When annual maintenance costs equal or exceed the equivalent annual cost of restoration, the restoration work is justified.
Restoration Versus Resurfacing
It is more difficult to identify the latest point in the pavement's life at which restoration is likely to be cost-effective, i.e., the point at which the pavement has carried so much traffic and sustained so much structural damage that an overlay is needed. It is conceivable that resurfacing may be done before this point and be more cost-effective than restoration, primarily because of the ability of overlays to reduce deflections and slow deterioration in the slab. Early resurfacing seldom oc-
222
curs, however, because of funding limitations . More frequently, restoration is performed some years after the time when it has the greatest potential to cost-effectively extend the pavement's life, and in some cases, after the time when a structural improvement is wammteri. The longer the delay, the less likely it is that restoration will be able to compete with resurfacing in performance and cost-effectiveness.
Indicators of Structural Deficiency
The following is a list of key distresses and levels that should be considered in assessing structural damage in jointed concrete pavement. The critical values suggested are based on observations of joint plain concrete pavement (JPCP) and joint reinforced concrete pavement (JRCP) performance in previous studies ( 4-6) as well as from the data base, and from use of EXPEAR (7) to predict the performance of restoration on pavements with varying levels of deterioration.
1. Transverse cracking provides direct evidence of fatigue damage. In JRCP, low-severity cracks are considered a normal consequence of drying shrinkage after construction, and are not considered structural distresses. In JPCP, unless the joint spacing is too long, transverse cracking of any severity is evidence of structural damage. Suggested critical levels for transverse cracking are 10 percent slabs cracked or 70 cracks per mile (all severities) for JPCP, and 70 cracks per mile (medium or high severity) for JRCP.
2. Longitudinal cracking in highway pavements is almost always caused initially by factors other than traffic (e.g., poor joint construction or foundation movement), but under traffic it can deteriorate to such an extent that it constitutes structural damage. More than 500 ft of longitudinal cracking per mile is suggested as a critical level for both JPCP and JRCP.
3. Joint faulting and pumping are not generally considered structural distresses, but they are caused by traffic loads and are visible indications of progressive loss of joint load transfer and erosion of slab support. Suggested critical levels of joint faulting are 0.10 in. for JPCP and 0.25 in. for JRCP.
4. Corner breaks, which occur as a result of substantial erosion of slab support and high corner deflections, are definite indications of structural damage. The suggested critical level for corner breaks is 25 per mile for both JPCP and JRCP.
5. Transverse joint spalling that reduces the thickness of the slab at the joints should be considered structural damage because it diminishes the structural integrity of the slab and is progressive in nature. It is often caused by poor joint construction, dowel bar corrosion, D cracking, or reactive aggregates. Suggested critical levels for joint spalling are 50 spalled joints per mile (medium or high severity) for JPCP and 25 spalled joints per mile (medium or high severity) for JRCP.
If JRCP or JPCP exhibits levels of structural damage beyond those listed, the pavement has probably reached or passed the point at which the rate of deterioration begins to accelerate rapidly. At this stage, a structural improvement is most appropriate. Restoration work performed on a pavement that has deteriorated past this point is likely to µrovidt: a relatively short performance life under medium to heavy traffic con-
TRANSPORTATION RESEARCH RECORD 1307
ditions. Attempting to delay a structural improvement by continued patching may result in annual maintenance costs so high that they completely offset any savings achieved by the delay.
Although visible distress is a good indicator of structural damage, it cannot give a complete picture of the extent of underlying deterioration. Coring and deflection testing are strongly recommended on any project being seriously considered for rehabilitation.
PAVEMENT EVALUATION AND REHABILITATION USING EXPEAR
EXPEAR is a computerized system to assist highway engineers in project-level evaluation of concrete highway pavements, development of feasible rehabilitation strategies, and prediction of rehabilitation performance and costeffectiveness. EXPEAR is intended for use in rehabilitation planning and design for high-volume (e.g., Interstate) conventional concrete pavements [JRCP, JPCP, and continuously reinforced concrete pavement (CRCP)]. EXPEAR was originally developed for the FHWA (7) and has been further developed with the support of the Illinois Department of Transportation (IDOT). Additional work on EXPEAR has been supported by the FHWA under this research study (8). Additional information on the development of EXPEAR is available (9-11). The current version is EXPEAR 1.4, which possesses the capabilities to do life cycle cost analysis and delay rehabilitation up to 5 years .
EXPEAR has been developed in the form of a knowledgebased expert system, which simulates a consultation between an engineer and an expert in concrete pavements. EXPEAR uses information about the pavement to guide the engineer through evaluation of a pavement's present condition and development of one or more feasible rehabilitation strategies. The procedure was developed through extensive interviewing of authorities on concrete pavement performance. In addition, predictive models are used to estimate future pavement performance with and without rehabilitation.
CASE STUDIES
Sections Evaluated
The data base developed under this contract includes 95 sections of JPCP and JRCP in their first performance period (6). Thirteen of these sections were selected for evaluation with the EXPEAR program. The sections, both JRCP and JPCP and located in all four major climatic zones, are presented in Table 1. The condition of each section was subjectively assessed as good, fair, or poor on the basis of observed distress and serviceability. Pavements rated as good had little or no cracking or joint deterioration, minimal joint faulting, no pumping, and a present serviceability rating (PSR) of 3.5 or more. Fair pavements had at least one of the following: moderate cracking or joint deterioration because of D cracking or reactive aggregate distress), moderate to high faulting (exceeding the critical level), visible pumping, or PSR less then 3.5. Pavements rated as poor had at least two and in most
Darter and Hall 223
TABLE I CASE STUDIES SELECTED FROM THE FHWA-ERES DATA BASE
Section Cllatat~ Joint Joint
Type Condition CrKkl"I ~tutori1Uon Fau!U"I Pwnpl"' PSR (no/mile) (no / mile) (Inch) (0-5)
AZ 1-6 DNF )PCP Good .0 5 0.01 None 3.5 FL 2 WNF ]PCP Good 0 0 0.01 None 3.7 MI 3 WF JRCP Good 0 0 0.02 None 4.8 MN3 DF JRCP Good 0 0 0.00 None 3.8 MN 2-3 DF JRCP Good 0 5 0.05 None 4.0
CA 1-3 DNF ]PCP Poor 30 10 0.10 Medium 3.0 MI 4-1 WF JRCP Poor 222 0 0.12 None 2.4 MI 1-lOb WF }PCP Poor 0 219 0.19 Low 2.8 MNl-8 DF JRCP Poor 102 141 0.09 None 3.4
Notes: Condition rating (good, fair, or poor) is subjective assessment of overall pavement
condition, based on visible distress and PSR in outer traffic lane.
Sections CA 6 and CA 1-3 have low-severity reactive aggregate distress.
cases three or four of the following: substantial cracking or joint deterioration (exceeding critical levels) , high faulting (exceeding the critical level), visible pumping, and PSR less than 3.0.
Evaluation Procedure
All EXPEAR input data required for each section were obtained from the data base. The following steps were carried out for each of the 13 projects.
1. Input data were verified by state employees and project team members familiar with the sections.
2. A pavement evaluation was concluded and future performance was predicted without any rehabilitation.
3. The following rehabilitation alternatives were considered:
overlay, crack and seat AC overlay, saw and seal AC overlay, bonded PCC overlay, and unbonded PCC overlay]; and
•Reconstruction with JPCP or JRCP.
4. Rehabilitation performance was predicted using models contained in EXPEAR for distress after restoration (faulting, cracking, joint spalling, and PSR), resurfacing (rutting and reflective cracking for AC overlays; faulting , cracking, and joint spalling for PCC overlays) and reconstruction (faulting, cracking, joint spalling, and PSR).
5. Life cycle costs were estimated using Illinois statewide average costs. The costs include traffic control and other miscellaneous costs normally associated with the alternatives (guardrails, signs , etc.).
Because of the highly variable nature of pavement rehabilitation costs throughout the United States, the cost analyses
should be considered only as examples for comparison of the relative cost-effectiveness of various strategies.
All of the projects were surveyed in 1987 and analyzed using EXPEAR in 1989. This 2-year delay is taken into account in the analyses: EXPEAR calibrates the performance prediction models to the 1987 distress and levels, predicts the distress levels in 1989, and uses these levels to compute rehabilitation quantities and costs . For some projects in very good condition, the rehabilitation was delayed an additional few years in the analysis .
AZ 1-6, Good Condition
Table 2 presents the results of the analysis of AZ 1-6, a section of 9-in. JPCP located on Route 360 near Phoenix, Arizona, in a dry, nonfreezing climatic zone. The pavement has carried about 2 million 18-kip equivalent single-axle loads (ESALs) in the outer traffic lane since its construction in 1981. When surveyed in 1987, its PSR value was 3.5, and the only notable distress was some joint spalling. Joint resealing had been attempted, without much success, a year earlier.
Given the low truck level on this pavement section, joint spalling on this pavement section is not predicted to increase significantly over the 20-year analysis period considered, and no other distresses are predicted to reach critical levels. As Table 2 indicates, the strategy with the lowest annual cost is restoration. Restoration could probably also safely be delayed for several years.
FL 2, Good Condition
Table 3 presents the results of the analysis of FL 2, a section of 13-in. JPCP located on 1-75 near Tampa, Florida, in a wet, nonfreezing climatic zone. The pavement has carried about 2 million ESALs in the outer traffic lane since its construction
224 TRANSPORTATION RESEARCH RECORD 1307
TABLE 2 RESULTS OF EXPEAR ANALYSIS OF AZ 1-6
PAVEMENT DESIGN HJghway: Route l6CJ near Phoenix Pavement type: 9-lnch JPCl' Year CONtructed: 1981 )olntspadng: lS-13-lS-17 feet Llowels: Und.oweled Base: 4-lnch Jean concrete Subgrade: A-0 Shoulders: Tied PCC outer, AC Inner Drain&: No dnin11
TRAFFIC Current 2-way ADT: Percent trucks: Lanes each direction: Accumulated ESAL:
97,770 3.8 3 2.01 milUon (outu lane)
EXISTING PA VllMENT CONDmON Year surveyed: 1987 PSR: 3.5 Deteriorated cracks: 0/mlle Deteriorated jolnte: 5/mlle (outer lane)
PHYSICAL TBS11NG Rl!COMMl!NDATIONS No phyJk<l t .. tlng W<ttant\'d.
PUl'URI! CONDmON WTlllOUT Rl!HAlllLTT A TION Some Joint dolrriontlon lo praen~ but no tlgn!Qcant l~rt'Uf' ol 1ny typo of diiltrlotaHon Is pft'dkbd over the not ;o.yt•r p1riod .
in 1986. When surveyed in 1987, its PSR was 3.7, it had no cracking or joint spalling, and faulting at transverse joints averaged only 0.01 in. The only distress noted was lowseverity joint sealant damage.
As Table 3 indicates, the only rehabilitation work needed is joint resealing, which could be done now or delayed a few years with no adverse affects. No other rehabilitation is predicted to be required for this pavement for the next 20 years. It is obvious that none of the available overlay strategies could compete in cost-effectiveness with restoration over the 20-year analysis period.
MI 3, Good Condition
Table 4 presents the results of the analysis of MI 3, a section of 10-in. JRCP located on 1-94 near Marshall, Michigan, in a wet, freezing climatic zone. The pavement has carried about 2.8 million ESALs in the outer traffic lane since its construction in 1986. When surveyed in 1987, its PSR was 4.8, it had no crack or joint deterioration, and minimal faulting. No significant distresses were noted. EXPEAR predicted that the condition of the pavement would be acceptable for at least another 9 years. No restoration or other rehabilitation is warranted now. However, the pavement was underdesigned for the traffic levels anticipated on 1-94, and full-depth repair of deteriorated joints and cracks will probably be needed in the future.
CONSEQUl!NCE OF Dl!LAYING Rl!HABILITATION R...,bllltttlon may <tidy be d<Llyed. Soo>e Joint mealing and joint tp;tll Rpalr ii recom01cnd('(I .
PREDICTIID LlFI! OF Rl!HABILITATION
Alternative Restoration 3-lnch ACOL 5-lnch crack/seat AC OL 3-inch .taw /seal AC OL 3-lnch bonded PCC OL 8-lnch unbonded PCC OL 9•h\t:h tt<ON:INcdon
Yan Unacceptable 20+ 7 Rel. eta.eking 6 Rutting 8 Rutting
20+ 20+ 20+
RESULTS OF UFl!-CYCLI! COST ANALYSIS
Initial Annual Altematlve Coot Cost Restoration 59,200 3,800 3-lnch AC OL 274,600 41,500 &-Inch aack/11eat AC OL 273,200 47,500 3-lnch saw/a,.I AC OL 284,300 38,200 3-lnch bonded PCC OL 368,800 2.3,400 II-Inch unbonded PCC OL 514,200 34600 9-lnch recomtru.ctlon 506,000 34000
Cost per 2-lane mile, bued on predlc:ted Uvet shown abow ('20 yt1r1 for bondtd overlay, unbond~ ov~rlay, and rtOOmtr.uctlon) uad dbcou.nt. nfe or 3 percent.
RECOMMl!NDl!D Rl!HABILITATION (1989)
Minot ft81onHon wort. (•pall ,.pair and joint .... aung) could be d.onc llo lmpmvo r1c1 .. bJUty and prevent water and lncOD\preulble lnflllntlon.
Table 5 presents the results of the analysis of MN 3, a section of 9-in. JRCP located on 1-90 near Austin, Minnesota, in a dry, freezing climatic zone. The pavement has carried about 1.5 million ESALs in the outer traffic lane since its construction in 1984. When surveyed in 1987, its PSR was 3.8, it had no cracking or joint deterioration, and minimal faulting . The only problem identified in EXPEAR's evaluation of the pavement was a possible subdrainage deficiency. As Table 5 indicates, subdrainage improvements could be done at low cost to ensure good long-term performance. There is no predicted need for other restoration work or other rehabilitation over the 20-year analysis period.
MN 2-3, Good Condition
Table 6 presents the results of the analysis of MN 2-3, a section of 9-in . JRCP located on 1-90 near Albert Lea, Minnesota, in a dry, freezing climatic zone . The pavement has carried about 2.8 million ESALs in the outer traffic lane since its construction in 1976. When surveyed in 1987, its PSR was 4.0 , it had no cracking, some joint spalling (5 per mile), and some joint faulting (0 .05 in.). The transverse joints and laneshoulder joints are poorly sealed.
As Table 6 indicates , restoration could be performed now at low cost , or could safely be delayed a few years. The costs
TABLE 3 RESULTS OF EXPEAR ANALYSIS OF FL 2
PA VBMl!NT DESIGN Highway: 1·'15 near Tampa Pavement type: 13-ln<h JPCP, 14-loot lonet Year constructed: 1986 Joint •pacing: 13-12-111-19 feel Oowela: Doweled, 1.25-lnch diameter Base: 6-lnch untreated aggregate Subgrade: A-3 Shoulde": Tied PCC On.IN:
> 3.5 for 20 years c 0.10 lnc:h lor 20 yean 0/mlle for 20 yean I/mile In 20 yean
CONSBQUBNCB OP DBLAYING lll!HABn.rTATION Othor than .... allng tnnovene jolnls, no major rehlbUltltton ls requlred now or over the next 20 yean. Rne1.llng may be delayed 1 few ye.rs with no advet1e effects.
PRBDICTED LIFI! OF REHABILITATION
AlttrNtlve Yun UnacCll!ptable Rettondon 20+
RESULTS OF LJFJ!.CYCLB COST ANALYSIS
Altem.atlve Rettoration
lnldal Coot
19,900
Annual Coot
1,100
Cost per 2--lane mile, hued on predicted life 1hown above (20 yean) •nd discount rate of 3 percenl
PSR > 3.0 over 20 years > 27 / mUe In 2D03 > 75/mlle In 1996 < 0.25 Inch ov'-r 1.0 yu .r.:.
CONSBQUBNCB OP DELAYING Rl!HABJUTATION None.
PREDICTED LIFI! OF REHABIUTATION No tthlbilUaUon needed fot al lt.u t .9 ycan..
RESULTS OP LJFJ!.CYCLB COST ANALYSIS None.
RECOMMENDED Rl!HABILITATION No rehabilitation ls needed for at leut 9 yean. At that lime, full-depth repair of joints and cn1.cb wW be needed. The pavement wn unden:letlgned for the very heny tr,lfflc on (-94.
TABLE 5 RESULTS OF EXPEAR ANALYSIS OF MN 3
PA VEMEN"I' DESIGN HJghway: ].90 near Awttn Pavemenl lype: 9-lnc:h JRCP Year coNtructed: 1984 joint opadng: 27 feet Dow11l111 1-lnd\ diameter Reinfon:ement: 0.054 lnJ/ft Base: ~Inch untreated Subg,.de: A-4 Shoulder>: AC DnlN: None
Shoulder condition: Good t.ne/1houlder joint: Poor
Ovetwll; Only minor dol<rlontlon. A subdralluge ddkkrv:y lJ lndlcal<d by de.,. buc, lmpormoabl• oubgr>dt, lnad<qu&I<: dltd"" and hHvy tTOfA<.
PHYSICAL TESTING RECOMMENDATIONS No dtDocllon '"'~ need«! . Cori"' 11 crnltr slab. Co,. <or1mlnadon and malOrlab lt<!Wg. Including p<tmubtllty of but. No '°ughnao or •kid """"II needtd .
CONSEQUENCE OP DBLAYING llEHABll.ITATION Joint_ datcdonitlon rt\l)' lncfUU!' If Joint 1Nl1nt i5 not tepJacfd, lb:«sslvc \v.at r NY ti\lfr Jrttion If longiludlnal lanc/1houldor Jol.nt n<>I t<ff•lcd.
PREDICTED LlPB OP llEHABll.ITATION (1992)
AJt.,naUvc lt8tona.Uon
Yu.n Unac<wpl.&ble 20+ Joint dt1ttrlo111tion
RESULTS OP LIPll-CYCLE COST ANALYSIS
Altem1dve Restoration
InllJal Con
44,500
Annual Cool
3,100
Coot p<r 2-l1n• mll•, tt...d on predlcred tile (W years) Ind discount RIO O( 3 p:.runt.
RECOMMENDED ltEHA8!UTAnON (1991) MlnQr rtstoullon work In 5 yurs may cxknd llfe of p1vement.
and quantities presented in Table 6 are for restoration work in 1992.
CA 6, Fair Condition
Table 7 presents the results of the analysis of CA 6, a section of 9-in. JPCP located on Route 14 near Solemint, California, in a dry, nonfreezing climatic zone. The pavement has carried about 4.4 million ESALs in the outer traffic Jane since its construction in 1980. When surveyed in 1987, its PSR was 3.4, it had no transverse cracking, and some joint spalling and longitudinal cracking. Faulting at transverse joints averaged 0.15 in. and the joints were not sealed. The PCC slab exhibited low-severity reactive aggregate distress .
As Table 7 indicates, EXPEAR predicted a relatively short life for restoration (6 years), primarily because more joint deterioration is predicted in the future as a result of the reactive aggregate. As a result, three overlay options have lower equivalent annual costs than restoration. The alternative with the lowest annual cost is a 3-in. AC overlay with sawed and sealed joints.
NC 1-8, Fair Condition
Table 8 presents the results of the analysis of NC 1-8, a section of 9-in. JPCP located on 1-95 near Rocky Mount, North Carolina, in a wet, nonfreezing climatic zone. The pavement has carried about 9.1 million ESALs in the outer traffic lane since its construction in 1967. When surveyed in 1987, its PSR was 3.3, it had some transverse cracking (20
227
per mile), some joint spalling (5 per mile), and faulting of 0.22 in. at transverse joints.
Although faulting is already high, the PSR is currently acceptable, and was predicted by EXPEAR to remain above the critical level of 3.0 for another 5 years. Rehabilitation could be performed now, or could be delayed a few years. As Table 8 indicates , restoration and overlay alternatives have comparable predicted lives, but restoration has the lowest annual cost.
NC 2, Fair Condition
Table 9 presents the results of the analysis of NC 2, a section of 11-in. JPCP located on 1-85 near Greensboro, North Carolina, in a wet, nonfreezing climatic zone. The pavement has carried about 5.8 million ESALs in the outer traffic lane since its construction in 1982. When surveyed in 1987, its PSR was 4.2, it had no transverse cracking or joint spalling, and minimal faulting. The only noted distresses were high-severity pumping and low-severity joint sealant damage, including a drainage deficiency. As Table 9 indicates, EXPEAR recommended that subdrainage improvements not be delayed. Excellent performance is predicted for restoration over the 20-year analysis period, and the annual cost is very low.
NJ 2, Fair Condition
Table 10 presents the results of the analysis of NJ 2, a section of 10-in. JRCP located on Route 130 near Yardsville, New Jersey, in a wet, freezing climatic zone. The pavement has
TABLE 7 RESULTS OF EXPEAR ANALYSIS OF CA 6
PA VEMBNT DESIGN HJghway: Roule Hi nt'.tr S!Jl~mlnt Pa.vement type: 9-lnch ]PCP Year constructed: 1980 Joint spacing: 12-13-15-14 leet Dowels: Undoweled Base: 4.2-lnch le1n concrete Subgnde: A·2 Shoulden: AC Drains: Drains present
PHYSICAL Tl!STING RECOMMENDATIONS Corlng at reprnentltlve deteriorated tnn1vene joints. Coring at longitudinal joint ond cnck. Teat 1tr<ngth of PCC 1wf1ce and lean conaete b11e. Observe eroelon at top ol l<an concroi. boK. l'otn>graphlc exom cl PCC for OIJ8"l'lt •Hc:Hvlty.
FUflJRB CONDIDON WITHOUT RllHABil.ITATION Fau!Hng: > 0.10 Inch Jn 1987
CONSEQUl!NCB OF DELAYING RBHABil.ITATION Faulting It cunenUy unacceptable.
PREDICI'ED LIPI! OP RllHABILITATION
Alternative Restoration 3-lnch AC OL 5-inch crack/seat AC OL 3-lnch 11w/1eal AC OL 7-inch unbonded PCC OL
Alternative Reslonlion 3-ln<h AC OL 5-inch crack/seat AC OL 3-lnch saw /seal AC OL 7-inch unbonded PCC OL
lnlUal Coot
248,800 312,900 406,800 335,800 619,400
Annual Cost
43,300 42,000 49,200 31,800 39,200
Cost per 2-Jane mile, hlted on predicted Jlvet shown above (20 ye.n for unbonded overlly) and dlscount n.te of 3 percent.
RECOMMBNDED RllHABil.ITATION (1989) 3-lnch AC overl1y wJth 11wed and se.Jed Jolnts Js the most costo4i!ffectlve 1llem1tlve, wlth a life of about 12 years.
Rchablllt.atlon TechnJque Pull-deplh ,..,.;,of jolnll Full-depth repair of crack! Reseal tnn1vene Jolntl Reoeol ione/1houlder joint 3-lnch ,.w /1eol AC OL
Quantity per 2-lane mile and ahoulden.
Quontlty 434 ay 10 •y
9910 ft 10560 ft 22293 •y
TABLE 8 RESULTS OF EXPEAR ANALYSIS OF NC 1-8
PA VBlllllNT DESIGN Highway: la95 near Rocky Mount Pavement type: 9-lnch )PCP Year comtructed: 1967 Joint •pacing: 30 feet Dow1l11 Undowclcd Bue: 4-ln<h unl1Ulod aggregalt Subgiade: A-2 ShouldetB! AC DnlN: No dralN present
TRAFFIC Current 2-way ADT: Percent trucks: Linea each direction: Accumulated ESAL:
Shoulder condition: Good Lane/shoulder jolnt: Poor
Overall: Excessive faulting indicates a load transfer defld enc)'. Some joint and crack deterioration present, redudns .t:(lnilct1• bUlty.
PHYSICAL TESTING RECOMMENDATIONS Defledlon test for structure an1lysU and void detection. Core at center of slab to obtain material samples. Core representative deteriorated. joints. Test strength of rec cores.
l!XISTING PAVEMENT CONDmON (outer lone) Year 1urveyed: 1987 PSR: 3.8 Deterlonted cncb: 24/mlle Crack faulting: 0.02 Inch Deteriorated joints: 14/mile Joint faulting: 0.06 inch Longitudinal cncks: 10 feet/mile Long. Joint spall: 141 .. t Pumping: None PCC surface: Not polished Joint sealant damage: High severity "IY cracklng: None Settlements/heaves: None
Shoulder cond I ti on: Good lane/shoulder Joint: Good
Overall: Some transverse crack and Joint detertontton. Some faulting at joints and cracks. Shoulden; are in good condition. Subd.r.lNge deftdency indicated due to dense-graded aggregate bi15e, A-4 subgrade, inadequate ditch depth and heavy b'affic. Joint sealant ls in poor condition.
PHYSICAL TESTING RECOMMENDATIONS Deflection testing needed for structural analysis and void detection. Coring and materials testing needed for assessing extent of deterioration, Materials testing for base permeability.
carried about 35 million ESALs in the outer traffic lane since its construction in 1951. When surveyed in 1987, its PSR was 3.8, it had 24 deteriorated transverse cracks per mile, 14 deteriorated joints per mile, and some faulting at cracks and joints. High-severity joint sealant damage was also noted.
On the basis of the observed distress and heavy truck traffic, EXPEAR predicted that the pavement's condition would remain acceptable for only another few years. As Table 10 indicates, restoration in 1989 would have the lowest annual cost of all of the alternatives, and predicted life of 8 years. If rehabilitation were delayed beyond that time, overlay or reconstruction options would probably provide lower annual costs and better long-term performance.
CA 1-3, Poor Condition
Table 11 presents the results of the analysis of CA 1-3, a section of 8.4-in. JPCP located on 1-5 near Tracy, California, in a dry, nonfreezing climatic zone. The pavement has carried about 7 .6 million ESALs in the outer traffic lane since its construction in 1971. When surveyed in 1987, its PSR was 3.0, it had 30 cracks per mile, 10 spalled joints per mile, and 500 ft of longitudinal cracking per mile. Faulting at transverse joints averaged 0.10 in., the joints were not sealed, and mediumseverity pumping was evident. The PCC slab exhibited lowseverity reactive aggregate distress.
Because the condition of the project is already unacceptable, rehabilitation should not be delayed. As Table 11 in-
FUl'tlRB CONDmON WllHOur REHABILITATION Servlceablllty: PSR < 3.0 In 2003 Deterto .. ted jolnb: > 27 /mile In 1990 Detertonted mdai: > 75/mlle In 1989
CONSEQUENCE OF DBLAYING REHABILITATION Th1J Is 1 very old pavement th.It haa carried a large amount of tnfflc and la now deterlocatlng (a1e:ldng1
jolnt deterlon.tlon and faulting). The pavement has some potential for restoration If done soon.
PREDlClllD UFE OF REHABILITATION
Alternative Yesn Unacceptable Restoration 8 Joint/crack
deterioration 3-lnch AC OL Ref. cracking,
rutting 5-incli crack/seat AC OL 10 Rutting 9-lnch unbonded PCC OL 14 Jt dttt'.riontion,
Inlti•I Alternative Coit Restoration 182,000 3-lnch AC OL 423,900 5-lnch crack/seat AC OL 488,300 9-lnch unbonded PCC OL 730,000 12-inch recomtructlon 6181800
Annual Coat
24,400 73,800 54,000 60,900 42,700
Con per 2-lane mile, hl.s.M on pttdlcted Dvcs ind dlJC'ount r11c of 3 perccnL Slnce ahould(lrJ" U1: Jn good condition, shoulder removal and replacement not included in cost of recorutruction.
RECOMMENDED REHABILITATION (1990) The restoration alternative ls the most cost-effective. If a life of 8 yean la acceptable, restoration is recommended. If not, recorutructlon Is recommended.
dicates, the annual cost of restoration is similar to that of an unbonded overlay or reconstruction, but the predicted life of restoration is fairly short. A significant unknown is the rate of progression of reactive aggregate distress in the concrete. Coring, strength testing, and petrographic examination of the concrete were recommended by EXPEAR to assess the aggregate's reactivity. Restoration is recommended only if the reactive aggregate distress is not projected to progress further. Otherwise, an unbonded PCC overlay or reconstruction is recommended.
MI 4-1, Poor Condition
Table 12 presents the result of the analysis of MI 4-1, a section of 9-in, JRCP located on 1-69 near Charlotte, Michigan, in a wet, freez.ing climatic zone. The pavement has carried about 4.4 million ESA in the outer rraffic lane since it construction in 1973. When surveyed in 1987, its PSR was 2.4, it had extensive transverse crack deterioration (222 per mile), moderate faul ting (0.08 in. at cracks, 0.12 in. at joints), and medium-severity joint sealant damage.
The pavement need immediate rehabilitation. As Table 12 indicate , restoration is a poor rehabilitation choice, in terms of both performance life and annual cost. The crack and seat AC overlay, saw and seal AC overlay, and bonded and unbonded PCC overlay options are all very close in predicted life and annual cost.
TABLE 11 RESULTS OF EXPEAR ANALYSIS OF CA 1-3
PA VllMENT DESIGN HJghway: 1·5 near Tncy Pavement type: 8.4-inch JPCP Year constructed: 19'71 Joint 'P'dng: IZ.-U-19-18 feet DnwPl1t: t Jnrtowtled Bue: 5.4-lnch cement.treated Subgnde: A-1 Shoulden: AC Dnim: No dnlM present
TRAFFIC Current 2-way ADf: Petcent trucb: Lanes each dlrectlon: Acrumulated F.SAL:
13,000 19.0 2 7.62 million (outer lane)
EXISTING PAVl!Ml!NT CONDmON Year surveyed: 1987 PSR: 3.0 Deterior.ted cncb: 30/mlle Deterionted Joints: JO/mile Joint l1uldng: 0.10 Inch Longitudinal cracks: 500 feet/mile Pumping: Medium rec 1ur{1C,., lined, not polllht'<I Jotn.1 ae1?.tnt damage: Hlgh 1111\.'(rtty (not aealed) "D' mcklng: N no Reactivt! •88ft8.•~ Low ;everity Settkmrntt/huve.: None
Altem1tlve Restonitlon 3-lnch AC OL 5-inc:h crack/seat AC OL 7-lnch unbonded PCC OL 9-lnch recorutructlon
lnidal Coot
180,000 419,000 442,000 600,000 603,000
Annual Coll
37,100 116,300 48,800 38,000 38,200
Cati pctr 1-lan~ mile, bl•i:d on predicted lives shown 11tbcv~ (20 yeari for unhanded ovtrl•)' and reconstrudlon) •nd discount rate of 3 percent.
RECOMMl!NOEO REHABILITATION (US9) Re1lo~ only Ir pt"trognphk 1n1Jyall lndk1t~ low •gg~alt reactivity. 01huwlle, overl1y with unboncftd PCC or rttONll'\Kt.
Ovenll; Traffic lines 1how extensive trlMvene crack dticrlor1lloftt but no jalnl dctcrtontion. Somt faulU1'4 •.Ult 1t lolnlt 11"1 <n<I". Shoulder> .... in good con<lldQI\. Subdr1IN&• d<fkl<ncy lndlcatt'<I by deMogr>ded '83~•,. bcH, A~ 1ubgndt, lnadf<!ualt dlt<h dtpth 1n<I ht•vy tralllc.
PHYSICAL TESTING RECOMMENDATIONS 0.Ut<llon !<>ling ne<ded for alNctursl 1noly>ll and void dt lrd.lon. Coring .and 1JU1rerl1lt ttttlna MftiC'd lot asaeutng VdetPl ol ddf'riontlon (ram •o· a-.-cklng (boch .......... Ind longltod lNI joint>). Mol<rl•IJ ,..«"41 for 1•>rrneablllty.
FUTURB CONDmON WITHOUT REHABILITATION Servlce1blllty: Deterlorsted Joints: Deteriorated crackJ:
PSR c 3.0 In 1987 > 27/mlle In 1997 > 75/mlle In 1987
CONSEQUENCE OF DELAYING REHABILITATION P"avHntti1 II 11tt1dy v.iry nJugh and nttd• bnmcdi1r~ ft'habllltatlon. l\ll lyptf of d•ltriontlon 1tt pr<dl<!td to lncniut lri Ntv"1. Pavt-rMnt la too dtleriorattd far retoraUon now. AC OYfrky may not be fe11lble due IO d•ttr!ondon ol rec >lob.
PREDICTED LIFE OP REHABILITATION
AltematJve Res ton ti on 3-lnch AC OL !I-Inch atck/seat AC OL 3-lnc:h 11w/1eal AC OL 3-lnch bonded PCC OL 7-lnch unbonded rec OL
Yun 5
10 15 13 15 17
Vnoccepllble Jt. deterioration R<I. crocking Rutting Rel. a.eking Ref, cncklng Jt deterlorwtlon, en eking
RES UL TS OF LIFB-CYCLE COST ANALYSIS
Altematlvit Raton ti on 3-lnch AC OL 5-tnch aock/1eot AC OL 3-lnch llW/Hll AC OL 3-lnch bonded PCC OL 7~nch unbon<led PCC OL
Table 13 presents the results of the analysis of MI 1-lOb, a section of9-in. JPCP located on US-10 near Clare, Michigan, in a wet, freezing climatic zone. The pavement has carried about 0.9 million ESALs in the outer traffic lane since its construction in 1975. When surveyed in 1987, its PSR was 2.8, it had extensive joint deterioration (219 per mile) , faulting of 0.19 in. at joints, extensive longitudinal joint spalling (1,395 ft per mile), low-severity pumping, medium-severity joint sealant damage, and medium-severity D cracking.
As Table 13 indicates, the pavement has too much deterioration for restoration to be cost-effective. An unbonded PCC overlay is the best rehabilitation choice in terms of performance and annual cost.
MN 1-8, Poor Condition
Table 14 presents the results of the analysis of MN 1-8, a section of 9-in. JRCP located on I-94 near Rothsay, Minnesota, in a dry, freezing climatic zone. The pavement has carried about 5.5 million ESALs in the outer traffic Jane since its construction in 1970. When surveyed in 1987, its PSR was 3.4, it had extensive crack deterioration (102 per mile), joint deterioration (141 per mile), and longitudinal cracking (1,775 ft per mile). Faulting at transverse joints averaged 0.09 in . Low-severity D cracking and joint sealant damage were also noted.
The pavement's condition is currently unacceptable. As Table 14 indicates, the rehabilitation strategies with the lowest
231
annual cost are reconstruction and unbonded PCC overlay. Because no preoverlay repair is involved (i.e., increases in distress quantities do not affect strategy cost), either reconstruction or an unbonded overlay could be delayed a few years. Despite the large amount of distress present , rideability is still acceptable, so some delay in rehabilitation could be tolerated.
SUMMARY
The pavements examined here that were in g od condition had minor faulting (average of 0.02 in .), little or no joint spalling or load-related cracking, and good ride quality (PSR greater than 3.5) . For these pavements, restoration was consistently the most cost-effective rehabilitation strategy.
Pavements in fair condition had greater faulting (average of 0.11 in.), moderate joint spalling (average of 5 joints per mile) and load-related cracking (average of 11 cracks p r mile) , and fair ride quality (PSR great.er than 3.0) . Restoration was the mo t cost-effective rehabilitation trategy for four of the five case studies in fair condition. The exception was a pavement that had joint deterioration because of reactive aggregate .
The pavements in poor condition had high levels of fau lting (average of0.13 in .) , a large number of spalled joints (average of 92 per mile) and load-related cracks (average of 88 per mile), and poor ride quality (PSR of 3.0 or less) . In every case examined, overlay or reconstruction was more costeffective than restoration .
TABLE 13 RES UL TS OF EXPEAR ANALYSIS OF MI 1- lOb
PA Vl!Ml!NT DESIGN Highway: US 10 near Clare Pavement type: 9-lnch ]PO' YeAr conatn.icted: 19'75 )olnt opadng: 1~19-lS.12 feet Dowels: Undoweled Relnfon::ement: None Base: ~Inch aspNlt-treated Subgr.tde: A-2 Shoulder.: AC On ins: None
TRAFFIC CWTent 2-way AOT: 5,100 Percent trud.9: 8 Lanes each direction: 2 Accumul11ed ESAL: 0.88 million (outer lane)
EXISTING PAVEMENT CONDmON (outer lane) Year surveyed: 1987 PSR: 2.8 Deterior1ted cr.tclc.s: O/mile Crack faulting: 0.00 inch Deteriorated joints: 219/mlle Joint faulling: 0.19 inch Longitudlnal cracks: 0 leet/mlle Long. jolnt spall: 1395 feet Pumping.: Low PCC surface: Tined Joint sealant damage: Medium severity "D" cracking: Medium Settlements/heaves: None
Shoulder condition: Good Lane/ shoulder joint: Good
Overall: Traffic lanes show exlenslve joint deterioration from •o• cracking. Serious faulting f.)tl;n::s. Should~n 1n: in good condition.
PHYSICAL TESTING RECOMMENDATIONS Det1ectlon lesdng needed loc structural analysis and void detedi.on. Coring and materials testing needed for assessing extent of deterioration from "D" cracking (both transverse and longitudinal jolnbi). No roughnes.1 or skid testing needed.
PUl'IJllE CONDmON WITIIOUT llliHABILITATION S.rvlc .. blUty: PSR < 3.0 In 1981 l\tulll.., > 0.10 Inch In 1987 Dettrio,.t<d join,.: > "/mile In 1\187
CONSEQUENCE OP DBLAYING REHABILITATION Pavement too deteriorated for restoration. Tnmverse and JongltudlN1 Joint d'tuiontJon wlli inaY:.He. AC overfly may not be feulbl~ duin to dettrlor11lon of PCCslab.
PREDICll!D LIPl! OP REHABIUTATION
AlterNtlve Restoradon ~Inch AC CL 7-lnch unbonded PCC OL
Yun Un..:cept.abl• !I Jt detl!rioration
17 Ref. crocking 20+
RESlJLTS OP LIFE-CYCLE COST ANALYSIS
Alternative Restoration ~lnchACOL
7-lnch unbonded PCC OL
Initial Coot
718,200 929,500 567,400
Annual Coll
143,500 6 .. 600 34,900
Cost per ~lane nUle, based on predicted lives shown above and dlscount rate of 3 percent.
RECOll{MENDED REHABILITATION (1991) 7-jnch unbonded PCC overlay with no additional rt'lpllr ls the tnQSt cml-coffective 1ltcrR1tlvt. due lo
h.1n1lve tep.-11' n.ttdN for other alhtmatl"es·
Rehablllti.tion Technlque1 Unbonded PCC OL traffic lanea AC OL 11hou1ders
102/mile 0.00 inch 141/mllc 0.09 Inch 1175 feet/mile None Tined Low severity low•verily None
Shoulder condition: Good Lane/shoulder joint: Good
Overa11: Traffic lanes have a large amount of deteriorated transverse and longitudinal cracks and joints.
PHYSICAL TESTING RECOMMENDATIONS Oo0«11on letting tor Alru('tur,.1 ana1y.i1J 4nd vold dctttdt>n. Coring 1t ccn\c-r tl.1b1 mar lranto . Jolnlt and lonsh11dlnal jolnl5. Coro ~mln.11Jon 1.nd ltUl lt"rials testing.
The cost of rehabilitation is strongly tied to pavement condition, as follows:
Average Initial Cost Average Annual Cost Condition Per Lane-Mile ($) Per Lane-Mile ($)
Good 32,000 2,000 Fair 163,000 16,000 Poor 605,000 45,000
It pays, therefore, to maintain pavements in good condition and to rehabilitate them before they exhibit substantial distress.
In the case studies examined, an AC overlay with sawed and sealed joints was usually the most cost-effective AC overlay option. A 3-in. AC overlay with sawed and sealed joints was predicted to last longer and be more cost-effective than a conventional AC overlay of the same thickness. A 5-in. AC overlay of cracked and seated pavement typically was predicted to perform better than a conventional 3-in. AC overlay. However, the cost of cracking and seating and the cost of the additional 2 in. of AC resulted in a higher life cycle cost about half the time.
The unbonded PCC overlay provided the longest life of all overlay alternatives and was found to be cost-effective when the existing pavement was badly deteriorated. Reconstruction was cost-effective if the existing pavement exhibited extensive deterioration and the shoulders were in good enough condition that they did not need to be replaced.
FUruRE CONDmON WITHOUT REHABnITATION Scrviceablllty: PSR < 3.0 in 2004 Deteriorated joints: > 27/mlle in 1987 Deteriorated cracks: > 75/mlle in 1987
CONSEQUENCE OF DELAYING REHABilJTATION Joint dc1:trtora1lon •-nd crack deterioration are a1n:ally unn.a:ept1ble. Further delty ln rehabltitailon would substantially increase maintenance cost and the cosl of n!habilitation.
PREDICTED LIFE OP REHABILITATION (1992)
AltemaUve Restoration 3-lnch AC OL
Yean Unacceptable 6 F1uhing
10 Rutting, ref. cracking
7-lnch unbonded PCC OL 16 Jt. deterioration 9-inch reconstruction 20+
RESULTS OF LIFE-CYCLE COST ANALYSIS
lnlUal Alternative Cost Restoration 599,000 3-inch AC OL 748,000 9-lnch reconstruction 633,600 7-inch unbonded PCC OL 704,000
Annual Cost
104,000 83,000 42,600 52,900
CCKI per 2-1ane milt>, bind Un pn:dlcte:d Jives shown above (20 years for rt'<OtUlrucUon) and discount rale of 3 percent.
RECOMMENDED REHABnrrAnON 11992) ReconslruC'tlDn hH lowest annual ((!Sl; unbonded rec overlay also provides acceptable life at low annual cost.
Rehabilitallon TechnJques
Reconstruct both traffic lanes Reconstruct AC shoulden
Quantity per 2-Jane mile and shoulden.
Quantlty
14,080 sy 9,387 sy
Overall, the EXPEAR program provided realistic evaluations, future predictions, and selection of alternatives for the case studies.
ACKNOWLEDGMENTS
The research reported in this paper was part of a study entitled "Performance/Rehabilitation of Rigid Pavements" conducted for the FHWA by ERES Consultants, Inc., of Savoy, Illinois. The contract officer's technical representative for the study was Roger Larson. Kurt Smith and Sue James of ERES Consultants are gratefully acknowledged for their assistance.
REFERENCES
1. M. J. Darter, E. J. Bnrcnberg, and W. A. Yrjanson. CHRP l?uporr 281: Join/ Repair Methods for Portland C11mvnt Concrete Pavements. TRB, National Research Council, Washington, D.C., 1985.
2. ERES Consultants, Inc. Techniques for Pavement Rehabilitation. Participants' Notebook, 4th ed., National Highway Institute and FHWA, U.S. DcpHtment of Transportation, 1987.
3. Concrete Pavement Restoration-Performance Review. Pavement Division and Demonstration Projects Division, FHWA, U.S. Department of Transportation, 1987.
4. M. B. Snyder, M. J. Reiter, K. T. Hall, and M. I. Darter. Rehabilitation of Concrete Pavements, Volume I-Repair Rehabilitation Techniques. Report FHWA-RD-88-071. FHWA, U.S. Department of Transportation, 1989.
Darter and Hall
5. M. l. Darter, J . M. Becker. M. B. Snyder, and R. E. Smith. NCHRP Repol'I 277: Co11cre1e P11 veme111 Eva/11111io11 Sys1e111 (COPE ). TRl3. National Research uncH , Washington, D. ., 1985.
6. K . D . Smith. D. G. Peshkin . M. l. Darter, A. L. Mueller, and . H. Carpenter. Performance of Joi11111d oocre10 Pn Peme111s,
Vof!lme l - £va/11a1io11 of 011cre1e l'nve111e111 l'erfomumcli m1 Design Fea111re . Report FHWA-RD-89-136. FHWA , U.S . De· panment of Transportation, 1989 ..
7. K. T. Hall , J. M. onnor. M. I. Darter. S. H . Cnrpenter. Re· habiliu11/011 of 011cre1e Pt1ve111e111 , Vo/11111c Ill - Co11 rete Paveme111 £1111l11fllio11 mul Relwbilitfllio11 ystem, Report HWA-RD·
-073. Fl-IWA. U.S. Department of Tran p nation. 1989. 8. M. I. Darter. and K. T. Hall . S1r11c11.1ral 011er/ay S1ra11:-ie for
Joimetf Concrete Pavcme111s, Volume fll-011ideli11es for the Selection()! Relwbili1111io11 Aliematlves. Report FHWA-R D-89-145. FHWA. U.S. Department C>f ransportation, 1989.
233
9. K. T. Hall. M. l. Darter, •. H. arpcnter, and J . M. onnor. Development of a Demon trntion Prototype o.ncrete Pavement Evaluation ystcm. In Tmnsporra1io11 Research Record 1117, TRB, National Research ouncil, Washington, D . . 19 7.
10. K. T . Hall J . M. Connor. M. I. Darter. and S. H. arpcnter. Development of an Expert System for oncnHe Pavemem Evaluation aDd Rehabilitation . Proc .. 2nd North A111erica11 Co11ference on Managing Pavements, Toronto, Ontario, Canada, Nov. 1987.
11. K. T. Hall , J . M. onnor, M. I.. Daner and S. H. Carpenter. Expert Sy. tem for Concrcre Pavement Evaluation and Rehabilitation. In Tra11spor1n1io11 /fr enrc/1 Recor<l 1207. TRB, National Research Council, Washington, D.C., 1988.
Publication of this paper sponsored by Committee on Pavement Rehabilitation.