Presentation on theme: "Long-Term Durability of Full-Depth Reclamation using Portland Cement"— Presentation transcript:
1 Long-Term Durability of Full-Depth Reclamation using Portland Cement The Washington State County Road Administration BoardDesigning for Society:Knowledge, Innovation, and SustainabilityLong-Term Durabilityof Full-Depth Reclamationusing Portland CementGregory E. Halsted, P.E.Program Manager – SC/RCC PavementsPortland Cement AssociationOctober 8, 2008Spokane, Washington
2 "Improve and expand the uses of portland cement and concrete." Since its founding in 1916, the Portland Cement Association has had the same mission:"Improve and expand the uses of portland cement and concrete."DivisionsMarket PromotionResearchTechnical ServicesCodes and StandardsAffiliatesAmerican Concrete Pavement AssociationThe CTL GroupCement Association of Canada
4 Definition of Reclamation Method of flexible pavement reconstruction that utilizes the existing asphalt, base, and subgrade material to produce a new stabilized base course for a chip seal, asphalt, or concrete wearing surface.Alternative Terms:Full-Depth Recycling (FDR)Full-Depth Rehabilitation (FDR)Cement Recycled Asphalt Base Stabilization (CRABS)Cement-Treated Base (CTB)Cement-Treated Existing Roadway Materials (C-TERM)Cement Stabilized Reclaimed Base (CSRB)Full-Depth Reclamation with Portland Cement (FDR-PC)
5 Advantages of Reclamation Use of in-place materialsLittle or no material hauled off and dumpedMaintains or improves existing gradeConserves virgin materialSaves cost by usingin-place “investment”Saves energy by reducing mining and haulsEnvironmentally friendly
15 Long Term Performance of Full-Depth Reclamation Pavements Principal Investigator and Author:Imran M. A. Syed, PhD, P.E.Thomas L. Brown Associates, PC
16 Outline Background Purpose Work Plan Observations Conclusions Report PublishedOctober 2007
17 1 - Background Waste is the enemy of progress! Progressive public officials seek to reduce:TimeMaterialsMoneySalvation of flexible roads typically include:Thick structural overlayRemoval and replacementWorn out asphalt pavements (lost resiliency) pulverized and stabilized with small amounts of portland cement to create a new roadway baseAlternative terms often lead to confusion
18 2 - Purpose Document long-term performance Summarize agency experience in FDRlaboratory design protocolfield construction techniquesproblems encounteredinnovative approacheslessons learnedShare results with others!
19 3 - Work Plan Literature review Candidate project selection through close coordination with the Portland Cement Association (PCA)State Departments of TransportationCounty agenciesCity agenciesPrivate developersInteraction with select officialsVisual Pavement Condition Survey (PCI)Extract cores for UCS measurementsSummarize findings in a Report
22 Pavement Condition Index (PCI) and Extracted FDR Cores The PCI is a subjective numerical rating of pavement condition, ranging from 0 (for the worst possible condition) to 100 (for the best possible condition)Dozens of core samples were obtained from the project study areas for unconfined compressive strength (UCS) determination
23 4 – Observations Over 150 roadways evaluated (79 in-depth) Overall - excellent long-term performanceAverage PCI of all study pavements was 89UCS of cores were from 260 to over 1000 psiCement contents ranged from 2 to 12 percentAverage cement content was 5 percentOwners are happy with the performance of FDR and plan to do more work in the futureNo major failures were observed that could be attributed to the cement-stabilized base
24 79 Projects Evaluated In-Depth average project age of roadways was 9 years
25 Montgomery County, New York Began reclaiming roadways in the late 1980’sStarted using FDR with cement exclusively in 2000PCI values average above 84Conducts freeze-thawtests during FDRdesign process10-inch base thicknessUses 4 to 6 percentportland cementOften incorporateswidening along withFDR projects
26 Texas DOT - Bryan District On rural farm to market (FM) systemFDR since 1996PCI values generally above 85Cement content 3 to 4 percentTypical 10-inch recycled layerwith two-course chip sealTTI evaluated 25 projectsStiff but not brittle baseMinimal shrinkage crackingImproved waterproofingTxDOT Pavement Design program indicated that an overlay is needed after nine years. So far the roads are doing well and no overlay!
27 Westminster, California Began FDR in 1989Thickness between 9 and 12 inchesPCI’s mostly above 85Utility cuts causing distressSlurry seal every 7 yearsOpen to traffic duringconstruction operationsTypically 6 percent cement2.75-inch asphalt surfaceGeotextile used in surfacelayer to reduce reflective crackingState provides credit for recycling50 percent cost savings
28 Idaho Transportation Department – District 6 Began CRABS in early 1990’sThickness between 6 and 9 inchesPCI’s above 85Environmental extremes!-40 to over 100 F8 to 30 inches rainOpen to traffic duringconstruction operationsTypically 2 percent cementITD does not allow the incorporation of subgrade soils in FDR work
29 Spokane County, Washington Started FDR program in late 1990’sPCI values either 99 or 1008 to 10 inches thick3 to 5 percent cementSpring load restrictionsreduced through FDRStrength reduced fromover 600 psi to less than400 psi (per PCA)Joint venture with local contractorsCounty does initial prep, compaction, and finishingContractor performs pulverizing and mixing work30 to 50 percent cost savings
30 5 – ConclusionsFDR is a successful technique providing highway officials a cost-effective tool to maintain the highway networkHigh cement contents can lead to very stiff bases causing shrinkage cracks in the pavement surfaceThe current trend is to lower cement contents and target seven-day UCS to between 200 and 400 psiMany agencies avoid cutting in to the subgrade% Cement
31 Conclusions“Portland Cement is probably the closest thing we have to a universal stabilizer.”Chemical Stabilization Technology for Cold WeatherUnited States Army Corps of Engineers, September 2002Since portland cement stabilizes many materials, it is considered as a “universal stabilizer” by most – expectations are highAgencies like to use portland cement to “dry” soilsMore water is used during construction and not enough during curing – leads to shrinkage problemsUse of standard Proctor vs. modified Proctor
32 Full Report60 pagesPCA SR016Summary4 pagesPCA IS689
33 for additional information, please visit the PCA website at
34 of Design and Construction of Full-Depth Reclamation “Fundamentalsof Design and Constructionof Full-Depth ReclamationPavements”Tomorrow!October 9, 2008 at 11:00 AM
35 Thank You! firstname.lastname@example.org I would like to thank you for your attention this afternoon and will be happy to answer any questions you might have.