CSIR Pavement Design Task Group Feedback RPF meeting 23 November 2005

CSIR Sequence of events Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) RPF May 2005 –Establish task group 1 st Meeting –Discussion of role and operation of the task group –Presentation on potential improvements to mechanistic- empirical (ME) design method –Unpacking of ME design method core 2 nd Meeting –Presentation on a project performance based design method –Presentation of simulation models –Discussion of the deliverable from the process

CSIR Sequence of events Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) 3 rd Meeting –Integration of the performance based information system and the ME-design component into a single design method –Design sensitivity analysis based on the current ME design method –Details of the performance based information system 4 th Meeting –Unpacking the details of the ME-design component –Development of a R&D matrix and rating of the R&D areas

CSIR Task group members Prof M de Beer (CSIR); Prof E Horak (UP); Mr M Henderson (PAWC); Prof K Jenkins (US); Dr F Jooste (MAS); Dr G Jordaan (Tshepega); Mr L Kannemeyer (SANRAL); Dr F M Long (MAS); Mr P Olivier (J&G); Mr B Perrie (C&CI); Mrs E Sadzik (Gautrans); Mr A Taute (Vela VKE); Mr H L Theyse (CSIR); Dr I van Wijk (Africon); and Dr H Wolff (Nyeleti).

CSIR General recommendations: Deliverable from the task group Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) The task group will deliver a research and development (R&D) plan that will guide the development of a pavement design method for southern Africa that –allows for a range of design applications of different importance and –caters for a user group with different levels of design experience R&D plan to be executed under the auspices of the Road Pavement Research Advisory Committee (RPRAC) –Project management may be referred back to sub-groups of the task group

CSIR General recommendations Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) The R&D plan is aimed at developing an improved design method based on –A performance based information system –Mechanistic-empirical design concepts Initial intention to include rigid and block pavement design –Details of design sufficiently different to treat separately –Urgent need to develop single design guide for all types of pavements

CSIR General recommendations Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) The R&D plan only covers R&D activities to develop improved design method –Dissemination of individual research results and design method as a whole –Not descriptive in terms of delivery mechanisms such as software packages –RPRAC may considered the development of a software package as a form of delivery mechanism The improved design method should close the gap between ME-design and day-to-day engineering as far as possible Conventional ME-design focus almost exclusively on the effect of the imposed stresses –Recent research on unbound material shows the effect of field variables such as density and saturation is equally important –The improved design method must incorporate the effect of field variables

CSIR General recommendations Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Initially a separate task group for design traffic –Design traffic estimation is an integral part of pavement design –Design traffic task group combined with pavement design task group –The improved design method should allow for gradual transition from the E80 concept to mixed traffic design Revision of guideline documents containing sound engineering practice excluded form the R&D plan –Close integration required between guidelines and the design method

CSIR Integration of guidelines and design method

CSIR Performance based information system Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Based on performance data collected from –Rehabilitation investigation documentation –APT test results Statement of fact rather than interpretation of data and modelling

CSIR Design Method Integration of performance based and ME-design components Entry level Intermediate level Advanced level ME-design component Design scenario: Routine design Low design experience Use only known materials Conventional material classification Design scenario: Important design Seasoned professional designer Test input parameters for materials Design scenario: Very important design Special investigations Specialist designer Unusual materials Test input and performance of materials Performance based information system

CSIR Design Option Click here for Design Report Click here for Situation Summary Click here for Rehab. Report Click here for Design Report Click here… Click here for Design Report Click here… Click here for Design Report Click here… 8 Years to Resurface 1278 H/day 8 MESA to Rehab Terminal Rut = 16 mm Not Resurfaced 987 H/day 5 MESA to Rehab Terminal Rut = 12 mm 11 Years to Resurface 1250 H/day 9 MESA to Rehab Terminal Rut = 14 mm 10 Years to Resurface 1400 H/day 12 MESA to Rehab Terminal Rut = 17 mm Performance Database Performance based information system

CSIR Mechanistic-empirical design component Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Basic ME procedure –Fully determines the accuracy of the ME-design component –Requires engineering knowledge and understanding Various implementation schemes –Allows for spatial and time-based variation –Enhances the interpretation of results –Requires mathematical and computer programming skills

CSIR Temperature Moisture content Density Grading Atterberg limits Binder content Binder properties Geometry Axle load histogram Other? Contact stress histogram Grading Fixed load Fixed contact stress M r = Constant M r = f (Temp) M r = f (Dens, saturation) M r = f (Bulk and shear stress) M r = f (Strain) Linear visco-elastic Other? UCS Stress and strain at break Time/previous loading HMA Unbound Stabilized Material data Traffic data Resilient response analysis Input layers CurrentFuture Resilient response models Damage models Fatigue Plastic strain/ permanent deformation Other? Thermal cracking HMA Unbound Plastic strain/ permanent deformation Other? Stabilized Stiffness reduction Plastic strain/ permanent deformation Other? Crushing Subgrade Plastic strain/ permanent deformation Other? Structural capacity estimate Computer solution

CSIR

Research & Development Plan Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Main components of the R&D plan –Integration level project –Performance based information system –Demand analysis Traffic and natural environment –Material response models –Pavement response models –Damage models –Probabilistic and recursive implementation schemes R&D needs formulated for each component Short, medium and long-term actions formulated for each R&D need Each action rated in term of benefit/impact and effort/cost

CSIR Execution of R&D plan: Integration of activities

CSIR Execution of R&D plan: Stress effect theme

CSIR Execution of R&D plan: Field variable effect theme

CSIR Rating of short-term R&D objectives Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Integration level project –Integrate output from R&D projects into single design method –Reality checks and validation –Develop manual on use of method

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Performance based information system –Capture performance of rehabilitation and APT projects –Present in user-friendly format

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Demand analysis –Tyre/pavement contact stress information system

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Demand analysis –Axle load and traffic volume information system

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Demand analysis –Guidelines on traffic surveys for pavement design

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Demand analysis –Vehicle dynamics

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Demand analysis –Environmental information system

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Demand analysis –Field variable information system

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Material response models –Calibration for appropriate parameters (time, density, saturation, temperature)

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Material response models –Agreement between different deflection methods

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Material response models –Documentation on testing and deriving design input

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Pavement response models –Correct model of tyre/pavement contact interface

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Pavement response models –Benchmark of measured stress and strain

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Pavement response models –Modeling vertical variation (temperature, density, saturation, stress dependency)

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Pavement response models –Modeling geometric non-linearity

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Pavement response models –Modeling material non-linearity No short-term items

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Damage models –Improved damage models for asphalt material

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Damage models –Improved permanent deformation models for unbound materials

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Damage models –Improved damage models for bound material

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Damage models –Improved modeling of total pavement damage

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Probabilistic and recursive simulation –Guidelines on collection and interpretation of statistical information

CSIR Rating of short-term R&D objectives (continued) Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Probabilistic and recursive simulation –Probabilistic, linear recursive and non- linear recursive simulation

CSIR Rating of short-term R&D objectives Summary Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Integration project and performance based information system –Average benefit ratings between 3,8 and 3,9 –Average benefit/effort between 114 and 190 % Demand analysis –3 out of 6 items had average benefit ratings between 3,5 and 3,9 the other items were between 2,8 and 3,2 –Average benefit/effort between 96 and 159 % Material resilient response models –Average benefit ratings between 3,6 and 4,1 –Average benefit/effort between 99 and 141 %

CSIR Rating of short-term R&D objectives Summary Scientific Research Council Act (Act No 46 of 1988, as amended by Act 71/1990) Pavement resilient response models –Average benefit ratings between 2,4 and 3,4 –Average benefit/effort between 70 and 98 % Damage models –Average benefit ratings between 3,6 and 4,4 –Average benefit/effort between 112 and 146 % Probabilistic and recursive implementation schemes –Average benefit ratings between 3,5 and 3,9 –Average benefit/effort between 132 and 152 %

CSIR Recommendation to RPRAC Select projects based on –Ratings –Recent and ongoing research that may fast-track certain projects –The achievement of the objective of the R&D plan to developed an improved design method for flexible pavements