Session 3: Concrete Pavement Evaluation

Transcription

1 Session 3: Concrete Pavement Evaluation

2 3.2 Learning Outcomes 1. Describe the need for a thorough pavement evaluation 2. Name the common pavement evaluation components 3. Describe what information is obtained from each pavement evaluation component

3 3.3 Introduction For an existing pavement, the overall goal is to provide a cost-effective solution that: Addresses pavement deficiencies Satisfies constraints Detailed pavement evaluation required to achieve this goal

4 3.4 Purposes of a Pavement Evaluation Provides qualitative information to: Determine causes of deterioration Determine if pavement is not a candidate for preventive maintenance Develop appropriate alternatives Provides quantitative information for: Quantity estimates Assessment of deterioration rates Performing life-cycle cost analyses

5 3.5 Data Required for Pavement Evaluation Pavement and shoulder condition Pavement design Materials and soil properties Traffic volumes and loadings Climatic conditions Drainage conditions Geometric factors Safety aspects Other factors

6 3.6 Project Evaluation Approach 1. Historical data collection/records review 2. Initial site visit and assessment 3. Field testing activities 4. Laboratory materials characterization 5. Data analysis 6. Final field evaluation report

7 3.7 Key Pavement Evaluation Components Pavement Distress and Drainage Surveys Deflection Testing Roughness and Surface Friction Testing Field Sampling and Testing Which activity is most useful in identifying candidate preservation projects?

8 3.8 Pavement Distress and Drainage Surveys

9 3.9 Purposes of Distress Survey Document pavement condition Identify types of distress Group areas of similar performance Gain insight into causes of deterioration Identify additional testing needs Identify possible treatment alternatives Identify repair areas and quantities

10 3.10 Pavement Distress Fundamental performance indicator Characterized by: Type What? Severity How Bad? Extent How Much?

11 3.11 Distress Identification Manual Standardized distress definitions Benefits More consistent calls Better communication within and between highway agencies Improvements in any agency activity using pavement performance information

12 Example Distress Manuals 3.12

13 3.13 Output of Distress Surveys Distress types and quantities Overall indicator of condition (PAVER, PASER, State DOT procedures) PCI Example Index EXCELLENT VERY GOOD GOOD FAIR POOR VERY POOR FAILED Repair Type Preventive Maintenance Minor to Major Rehabilitation Reconstruction

14 Common Concrete Pavement Distresses Corner Breaks D-Cracking or ASR Transverse Cracking Spalling Patch/Patch Deter. Joint Faulting Pumping Joint Seal Damage Blowup Map Cracking Punchout Scaling Longitudinal Cracking Table 3.3 on p

15 3.15 Class Exercise Distress Identification

16 Transverse Cracking 3.16

17 Pumping 3.17

18 Joint Faulting 3.18

19 Corner Break 3.19

20 Joint Spalling 3.20

21 Spalling Due to Joint Lockup 3.21

22 Joint Seal Damage 3.22

23 3.23 Transverse Cracking (Consecutive Slabs)

24 Blowup 3.24

25 Map Cracking 3.25

26 Alkali-Silica Reactivity 3.26

27 Longitudinal Cracking 3.27

28 3.28 Map (Plastic Shrinkage) Cracking

29 D-Cracking 3.29

30 Scaling 3.30

31 Patch Deterioration 3.31

32 Punchout (CRCP) 3.32

33 3.33 Manual Distress Surveys For project-level evaluation, manual procedures often preferred Gather records and information Windshield survey Distress survey Distress mapping Measurements Photos

34 3.34 Example Distress Form Blank Filled Out Fig 3.1 on p. 3.12

35 3.35 Drainage Survey Purposes: Identify moisture-related distress Document drainage conditions Assess overall pavement drainability Things to look for: Topography and cut/fill Pavement/shoulder slopes Condition and geometrics of ditches Condition of drainage outlets or inlets

36 3.36 Topography and Condition of Ditch

37 Condition of Outlets 3.37

38 3.38 Evaluation of Distress and Drainage Survey Results Distress Evaluation Summarize key distress data Prepare strip charts over project Evaluate historical trends Drainage Evaluation Overall pavement drainability Condition of ditches and outlets Evaluation of drainage times (DRIP program)

39 3.39 Slab Cracking Strip Chart Poor Drainage Fair Drainage Poor Drainage High Traffic Low Traffic % of Slabs Cracked Condition 1 Condition 2 Condition 3 Severity Low Med High Fig. 3.2 on p Distance Along Project

40 3.40 Closure Distress and Drainage Surveys Provides fundamental information on pavement performance General indicator of pavement deficiencies and needs Drives the need for additional field testing

41 Deflection Testing 3.41

42 3.42 Deflection Testing For pavement preservation work, valuable tool for assessing: Joint load transfer Presence of voids Structural adequacy Fast and produces repeatable results Commonly used in project-level analysis

43 3.43 Falling Weight Deflectometer Weight Drop Height Buffering System Weight Load Plate Pavement Seven Sensors Spaced at 12 inches Center to Center Fig. 3.4 on p. 3.17

44 3.44 Backcalculation of Material Properties Equations used to analyze deflection basins Provides estimates of PCC and subgrade layer strengths PCC elastic modulus Modulus of subgrade reaction (k-value) Backcalculated values used in design

45 3.45 Deflection Load Transfer 0% Load Transfer 100% Load Transfer Wheel Load Approach Slab Wheel Load Direction of Traffic Leave Slab Unloaded LT = Loaded Direction of Traffic Approach Slab Leave Slab Fig on p. 3.24

46 3.46 Void Detection with FWD Maximum deflection (typ. 20 to 35 mils) Load sweep and deflection plotting FWD load, kips APPROACH LEAVE Fig on p Corner Deflection, milli-inches

47 3.47 Closure Deflection Testing Not needed on all pavement preservation projects Provides information on load transfer capabilities, voids, and structural capacity Can have significant testing and analysis costs

48 3.48 Roughness and Surface Friction Testing

49 3.49 Why Assess Pavement Roughness and Friction? Roughness affects functional performance Roughness leads to increases in: Vehicle operating costs User delays Crashes Friction loss leads to increases in wet weather crashes

50 3.50 Pavement Serviceability Subjective measure of user s perception of pavement rideability Measurement scale 0.0 (very poor) to 5.0 (very good) Working range: 1.5 to 4.5 Basis for AASHTO design Correlations with other roughness indexes

51 3.51 Inertial Road Profiling Systems Equipment (IRPS) Measures actual pavement profile Widespread use in network-level pavement management Relatively accurate and repeatable measurements

52 Table 3.4 on p Roughness Indicators IRI current roughness measurement standard Serviceability (PSR) used in AASHTO General correlations: Ride Quality IRI PSR Good <95 >3.5 Acceptable <170 >2.5 Not Acceptable >170 <2.5

53 3.53 Why Assess Pavement Friction? Assess overall adequacy of pavement friction as it contributes to safety (especially wet-weather crashes) Identify localized areas with poor friction Curves Intersections Ramps

54 Definition of Surface Friction Force developed at pavement-tire interface that resists sliding Influenced by: Surface texture Microtexture Macrotexture Surface drainage (cross-slope) Fig on p

55 3.55 How Do You Assess Surface Friction? Historical method Measure friction directly ( skid number ) Must also consider surface texture Microtexture Roughness of individual aggregate Macrotexture General coarseness of surface Formed water channels (grooving) Large impact on surface friction

56 3.56 Friction Measuring Devices Locked-Wheel Trailer Does NOT measure texture!

57 3.57 Surface Texture Measuring Devices Volumetric ( Sand Patch ) method Outflow meter Circular track meter (CTMeter) High-speed laserbased devices

58 3.58 Closure Roughness and Surface Friction Provides indicator of functional performance Rideability Safety Possible need for testing indicated by user complaints and wet-weather crashes

59 Field Sampling and Testing 3.59

60 3.60 Purposes of Field Sampling and Testing Characterize material properties In absence of deflection data To complement deflection data Diagnose causes (mechanisms) of distress Identify existing material properties

61 3.61 Common Field Sampling and Testing Methods Coring Material sampling Dynamic cone penetrometer (DCP) Standard penetration testing (SPT)

62 3.62 Common Laboratory Tests Subgrade and granular base/subbase Characterization (soil classification, moisture content) California Bearing Ratio (CBR) Resilient Modulus (Mr) Stabilized layers and PCC slab Indirect Tension Unconfined Compression Special Materials Evaluation Tests

63 3.63 Closure Field Sampling and Testing Detailed field sampling and testing not needed on every project Information obtained from distress surveys will help identify needs Agencies should be selective in identifying testing needs, as many tests are specialized and costly

64 Review: Learning Outcomes 1. Describe the need for a thorough pavement evaluation 2. Name the common pavement evaluation components 3. Describe what information is obtained from each pavement evaluation component 3.64