Terence Milne South African Road Pavement Forum 13 & 14 November 2002 Conference Report Back: ICAP – 22 AUGUST 2002 COPENHAGEN AFRICON

ATTENDANCE  Over 40 countries represented by nearly 400 delegates  34 Delegates from South Africa

SCOPE OF CONFERENCE  Parallel Sessions  Design  Construction and Maintenance  Performance  Environment  Accelerated testing  Plenum Sessions

PRESENTATION  Examples of World Wide presentations  120 papers presented

PLENUMS  Perpetual Pavements  Endurance of 50 years  Asphalt Pavement Alliance (USA) Guidelines for Design and Construction  UK: Long life pavements  Europe  10 Road Laboratories Project

PLENUMS (cont.) e.g. Prof Per Ullidtz  Analytical tools for design of flexible pavements -Analytical – empirical method of pavement design Differences between the assumptions for analytical models vs the reality of pavement materials and behaviour  Keynote Addresses Linear electric theory vs back calculated layer moduli

PLENUMS (cont.)  Keynote Addresses  Analytical tools for design of flexible pavements Discrete element modeling deals with the forces on, and displacements of individual grains in a particulate medium

DESIGN  Binder Rheology  Belgium:  Looking at reliable standard testing method  Bending Beam Rheometer or Dynamic Rheometer  Long term ageing  USA  Uncertainty and appropriate use of CBR design of air fields  Japan  Structural design of airport asphalt pavements on soil with high water table  Design Parameters

DESIGN (cont.)  Material Models  UK  Constitutive material modeling for asphalt mixes  Elastic visco plastic model with input required from uniaxial test data (3 temperature and 3 displacement rates)  Netherlands  Design aspects for wearing courses on orthotropic steel bridge decks  Development of a FEM based model going beyond linear elastic theory  FEM modeling of elasticity, plasticity, cracking

DESIGN (cont.)  Materials Models  Netherlands  Tools developed for the better understanding of the interaction between the different components of the structure  Permanent deformation of asphalt concrete pavement: development of a non-linear visco elastic model for mix design analysis  FE simulations compared to real pavement data  South Africa  Non-linear visco elastic constitutive model to describe the rutting behaviour of asphalt

PERFORMANCE  The design and performance of thin surfacing layers  Europe:  Role of the binder considered  Possible failure criteria considered

CONSTRUCTION AND MAINTENANCE  Towards a Performance Related Seal Design Method  South Africa:  Japan and USA:  Compaction of HMA using a high frequency, double drum vibrating roller  Relationship between roller speed, vibrating frequency, number of roller impacts per metre and its effect on density obtained on a HMA pavement layer

IMPRESSIONS  Materials modeling based on fundamental materials characteristics using both Theoretical and Empirical relationships (reality always differs from a model with its assumptions)

IMPRESSIONS  Papers content ranged from highly involved simulations to practical papers such as roller compaction  Cost of technology  Europe and USA not always agreeing on the way forward  South Africa to take the best from both groups  Risk assessment in design using probabilities and modeling

IDEAS FOR CAPSA  Good mix of plenaries and specialist parallel sessions  Include all events in conference price to keep affordable, and delegates involved  Good idea of display in lunch and tea area  CAPSA compares well, personal touch too