Model Code 2020 will be a single code incorporating both new and existing concrete structures, that is both the design of new structures and all the activities associated with the assessment, interventions and the through-life management and care of existing concrete structures. Twelve action groups are developing the overall content and one of those, AG4, focuses on durability design. Within AG4 there are six task groups with thirty working parties between them on specific topics.
- Model Code 2010 will include:
- reliability concepts, that takes account of uncertainties and risk,
- integration of structural assessment and degradation rate to provide limit states with applicable reliability requirements,
- more comprehensive exposure zone guidance,
- guidance on early age cracking and allowable crack widths,
- use of performance-based concepts to remove inappropriate constraints on the use of novel types of materials and approaches,
- use of improved models for assessment of initiation including guidance on activation levels for above water and below water,
- models that account for the potential long propagation period that is incorrectly excluded in many durability assessments,
- models for abrasion, freeze thaw, leaching, water migration, chemical attack and internal attack.
- test methods for concrete mix acceptability and quality assurance,
- test methods for existing structures including concrete defect testing, in service strength assessment, corrosion tests, monitoring and sampling
- criteria such as activation level distributions for galvanised reinforcement, stainless steel, prestressing steel and fibre reinforcement,
- definition of test methods, and performance evaluation of concrete,
- performance requirements of concrete paste systems considering the chemical nature of the paste including admixture effects,
- repair systems evaluation and their durability and structural significance.
- recognition of the importance of robustness and redundancy,
- attention to the effect of material degradation,
This paper describes the work being undertaken and progress to date.
Mr Papworth is Chair of AG4.