Presentation on theme: "Earthwork Examine the materials and construction control process of earthwork operations to determine the degree of compliance with established standards."— Presentation transcript:
1 EarthworkExamine the materials and construction control process of earthwork operations to determine the degree of compliance with established standards.Ensure project level documentation is appropriate.Modify Specifications as needed.Work with LIMS to match specifications.Research new technologies for earthwork.Offer technical support to Project personnel
2 LOTs 120-8.1 Embankment Construction – LOTs What is the maximum length of a LOT?Mainline pavement lanes, turn lanes, ramps, parking lots, concrete box culverts and retaining wall systemsA LOT is defined as a single lift of finished embankment not to exceed 500 feet.Shoulder-Only areas, bike/shared use paths, and sidewalk areasA LOT is defined as 2000 feet or one Day’s Production, whichever is greater.Originally the 500 foot LOT size for most earthwork construction was developed for the “Contractor Quality Control” Specifications which the Department transitioned into from about the year 2000 to 2004.In 2007 the new 2000 foot LOT size was written into the specifications to reduce testing requirements for what may be called “non-traffic” construction. Shoulders, shared use paths, and sidewalks. If you notice, parking Lots are not considered in new LOT definition.Summary of LOT definitions. The 2000 feet LOTs for shoulders, bike paths, and sidewalk were added to the specification as a construction expedient. A specification change is coming that will remove “one Day’s Production”The Maximum length for a parking Lot (LOT) is still 500 feet.
3 Independent Verification Question from Industry – How is Independent Verification processed.Section Independent VerificationIn addition to the Verification testing, the Engineer may perform additional Independent Verification (IV) testing. The Engineer will evaluate and act upon the IV test results in the same manner as Verification test results.How do I go into independent verification. Do we need to discuss contractor quality control?If you a question about whether some are is compact or if the contractor is using the correct proctor, remember that as a representative of the Department you have the right and responsibility to take an independent verification test if there is a question about the quality of construction.With that in mind
4 Independent Verification QC Sample pcfVT Proctor pcfIV Proctor – 116 pcfResolution Proctor 116 pcfWhat proctor should we use?Should they resample the material?Independent Verification is implicit in the specifications.A proctor for base appeared low. The test results were QC 108 pcf. & VT 112 pcf. The Engineer choose to take an IV sample obtained 116 pcf.The question came to our office how to resolve this issue.In the case the Independent Verification does not compare with QC results. Therefore a resolution sample was obtained from the samples previously split and created and tested. Results compared with the IV tests and therefore the correct proctor is 116 pcf.The contractor could have decided to sample again and create three separate samples.
5 Reclaimed Asphalt Pavement (RAP) – 120-8.4 Where is RAP prohibited? Construction areas that are below the seasonal high groundwater table elevation.The top 12 inches of embankment.MSE Wall backfill.Minimize RAP content to avoid possible long term settlementWe have been asked informally several times if we can use RAP behind MSE walls in the reinforcement zone.Research indicates there is a potential for excessive long term settlement in RAP material.The use of RAP in MSE walls researched by Dr. Paul Consentino (April 2008)RAP is prohibited in in MSE walls because of the potential for long term deformations allowing the reinforcing straps that hold the walls to move. RAP is not allowed below MSE walls either.The use of RAP material for embankment has been addressed in memo’s and was added to the standard specifications in July 2007.
6 Reclaimed Asphalt Pavement (RAP) SpecificationsSoil & RAP mixtureProhibited in Retaining Wall SystemsAlternate Layer ConstructionShoulder Base 283Stabilizing Material 914
7 Requirements for max. 12 inch thick compacted Earthwork Max. Lift ThicknessTest Strip Requirements for 12 inch thick compacted lifts.– In the soil envelope - maximum allowed thickness of backfill is 6 inches.Requirements for max. 12 inch thick compacted EarthworkSectionEmbankmentPipe BackfillA-3 and A-2-4 soils with up to 15% finesNo Test strip requiredTest strip requiredA-1, Plastic materials, and A-2-4 Materials with greater than 15% finesSummary of 12 inch allowable lift thickness in Embankment, and Pipe Backfill.
8 Bedding Zone 4” below the pipe Soil EnvelopeTop Zone - Up to the base or final gradeSoil Envelope(No Thick Lift)1 foot above pipePIPECoverZoneThe soil envelope is the bedding zone(the bottom 4 to 12 inches that has been over excavated), cover zone (from the bottom of pipe to 12 inches above the pipe)The lowest zone is any backfill below the bedding zoneBedding Zone 4” below the pipeLowest ZoneBottom ofTrench
9 Reduced Frequency Testing How many passing density tests are required before the contract allows Reduced Frequency Density Testing for;Pipe backfillEmbankmentReduced Frequency in pipe backfill is allowed after 6 passing testsReduced Frequency testing allowed after 12 consecutive passing tests
10 Embankment -Reduced Frequency Reduced Frequency Testing is allowed after 12 passing tests with no Resolution tests in favor of Verification.Required to use similar compaction effort on the untested LOTSelect test location randomly from one of the two LOTs under consideration.Requires Engineer’s permission to place material over untested LOTNot allowed in shoulder only areas, sidewalks bike/shared use paths. (LOT size)Reduced Testing Frequency: When no Resolution testing is required for 12 consecutive verified LOTs, or if required, the QC test data was upheld, reduce the QC density testing to one test every two LOTs by identifying the substantiating tests in the Density Log Book and notifying the Engineer in writing prior to starting reduced frequency of testing. Generate random numbers based on the two LOTs under consideration. When Quality Control test frequency is reduced to one every two LOTs, obtain the Engineer’s approval to place more than one LOT over an untested LOT. Assure similar compaction efforts for the untested LOTs. If the Verification test fails, and Quality Control test data is not upheld by Resolution testing, the Quality Control testing will revert to the original frequency of one Quality Control test per LOT. Do not apply reduced testing frequency in construction of shoulder-only areas, bike/shared use paths and sidewalks.
11 Pipe Backfill –Reduced Frequency Testing is allowed after 6 passing tests with no Resolution tests in favor of Verification.Required to use similar compaction effort on the untested LOTSelect test location randomly from one of the two LOTs under consideration.Requires Engineer’s permission to place material over untested LOT
12 125 – Pipe BackfillPlastic and Metal pipe backfill requires 95% of Standard Proctor for density.Concrete pipe backfill requires 100% of Standard Proctor.Structure backfill requires 100% of Standard proctor regardless of the type of pipe joining the structures.
13 Metal Pipe / Structure Density Acceptance Metal pipe requires 95% maximum densityStructure requires 100% maximum densityThe pipe and structure require separate density tests because of different density requirements.This will be clarified in the July 2013 specificationsThe critical element when metal or plastic pipe join concrete structure is the metal/plastic pipe.If density requirements are different, Separate tests are required for Structure & Pipe in the cover zone. The July 2013 workbook will clarify this language.
14 Stabilization Materials- Sampling Commercial Material - Approved Source (usually Aggregate Base)Requires a Cert from the MineNo field sampling or testing requiredExisting BaseNo testing requirementsIV testing is encouraged and should be performed on any material if there are concerns i.e. bad clay or organic materials …Local MaterialsAcceptance requires:Source investigation (440 /440A– Projects let after 3/1/11 )Sample & test from the roadway for material acceptance(440/440B - Projects let after 3/1/11)
15 Stabilization - Local Materials Meet the requirements of Section (440/440A)Local material may be clay from on-site, material from another construction project, or possibly byproducts from a process.The Specifications require testing of the material before it is brought to the roadway and spread.SamplingSection 914 requires a minimum of 3 organic content test results and one LL/PI test result per source.The Engineer should partner with the contractor to investigate the source or stockpile and evaluate each material. (best practice)Use one sample card for each source or stratum of materialProvide a minimum of 3 - ½ bags of material for each source
16 C22 card “Remarks” - Enter “Source testing “ “Material ID” - Enter 440 for projects let prior to March 1, 2011 and 440A if the project is let after March 1, 2011 (This will show in the project job guide schedule)“Remarks” - Enter “Source testing ““Sample Number – Enter “C001”, “C002”, “C003”, etc and either “Q” or “V”
17 Roadway Acceptance – Local Material Sampling and Testing of Local Materials - Section (440/440B)Requires Sampling after spreading and before mixingQC 1 per 2 LOTs – VT 1 per 8 LOTs“Sample Numbering” - “C001”, “C002”, “C003”, etc and “Q” or “V”Collect three pint size bags of material across the roadway (FM 1 – T267)Engineer Verification, Resolution and AcceptanceStabilizing materials require acceptance before the material is mixed into the Subgrade
18 C-22 CARD Example“Material ID” - Enter 440 for projects let prior to March 1, 2011 and 440B if the project is let after March 1, 2011 (This will show in the project job guide schedule)“Sample Number” – Enter “C001”, “C002”, “C003”, etc and either “Q” or “V”“Plant or Pit No.” Enter “ROADWAY““QUANT REP” Enter “LOTS 1 thru 8”“Remarks” Enter “LL/PI and ORGANIC TEST”
20 RAP or RAP Blend Stabilizing Material Source Investigation (440/440A)Evaluate the stockpile as a local materialIf failing organic content is due to the asphalt content of RAP or RAP Blended material the department may modify acceptance (after careful evaluation)Modified Acceptance for RAP or RAP Blend (440/440B)Sample for LL/PI before mixingSample and test for Asphalt Content (FM 5-563) (NCAT) after MixingThe upper limit for FM in the mixed Subgrade is 4.7%Failure may indicate too much Asphalt or the presence of a material with a high organic content
21 Sampling for “RAP” Stabilizer Material Sample after spreading and before mixing according to (440/440B)Sample Transmittal Card Example:“Remarks”“RAP Premixing no organic test”“ LL/PI test only”Sample size is ½ bag
22 Sample for Asphalt Content Sample the material after mixing in (440/440B)Sample size is 1 bagSample Transmittal Card ExampleUse the same sample number as used for LL/PI testing“remarks”“RAP - Substitute FM for FM1-T267”
24 Independent Verification Standard Proctor Maximum Density Determination: The Engineer will verify the Quality Control results if the results compare within 4.5 lb/ft3 of the Independent Verification Verification test result. Otherwise, the Engineer will take one additional sample of material from the soil type in question. The State Materials Office or an AASHTO accredited laboratory designated by the State Materials Office will perform Resolution testing. The material will be sampled and tested in accordance with AASHTO T-99, Method C. The Engineer will compare the Resolution Test results with the Quality Control test results. If all Resolution Test results are within 4.5 lb/ft3 of the corresponding Quality Control test results, the Engineer will use the Quality Control test results for material acceptance purposes for each LOT with that soil type. If the Resolution Test result is not within 4.5 lb/ft3 of the Contractor’s Quality Control test, the Independent Verification Verification Test result will be used for material acceptance purposes.A proctor for base appeared low. The test results were QC 108 pcf. & VT 112 pcf. The Engineer choose to take an IV sample obtained 116 pcf.The question came to our office how to resolve this issue.In the case the Independent Verification does not compare with QC results. Therefore a resolution sample was obtained from the samples previously split and created and tested. Results compared with the IV tests and therefore the correct proctor is 116 pcf.A1