Life-time prediction of high-performance concrete with respect to durability

1. Life-time prediction of high-performance concrete with respect to durability Major Objective: Development of deterioration models and life-time design concepts for high-performance concrete(HPC) under different environmental conditions and exposure classes Work program: Investigation of all relevant HPCproperties with identification of damage mechanisms, service-life estimation and final definition of hints (Fig.1) Variation of additives +admixtures, cement, air (A) Mix design/ composition Mixing order, SP dosage,etc. (B) Production Lab testing by appropriate test methods Rheology, workability, etc. (C) Fresh concrete properties • Results: • Understanding and avoidance of damages of HPC due to practical conditions • Know-how about optimal composition of HPC mix designs with regard to rheological aspects and damage protection • Adjustment of existing test methods to the behaviour of HPC • Estimation of a service-life of HPC constructions under various climates • Achievement of a fundamental database and an unified European level Strength, pore size distr.,etc. (D) Hardened concrete properties Accelerated lab testing simulation of attack type standardized by test methods, testing of 66 mixes Durability Description of deterioration process and definition of recommendations for application Freeze-thaw Input of data into database Frost-salt Cyclic temperature Field testing of 22 mixes per region at totally 9 teststations all over Europe, covering different climatic conditions Acid Seawater Analysis of in-service structuresapp. 60 existing structures with differences of climate, application type and mix design Fire Shrinkage Fig.1: Summary of work program Main output:Manual with recommendations and hints regarding HPC application and service-life estimation, including acceptance criteria and production rules(2) (Fig.2) ← Effect of w/b ratio on drying and autogenous shrinkage, for HPC and OPC (w/b=0.50). Applied test procedure Implementation of test procedure Exposed aggregate from severe scaling of surface paste layer ↓ Amendments of test method for HPC e.g. shrinkage Lab performance Performance of HPC under different exposure conditions (D) Field performance Mix design and production rules (A), (B) Properties of HPC (C), (D) e.g. frost-salt Review of in-service structure e.g. frost General assessment and recommendations for mix designs e.g. seawater Service-life evaluation Exposure classes (EN206) Prediction of corrosion initiation period where: t: period of corrosion initiation in year, xc: cover thickness in mm, a, b: regression constants, a = 0.212 and b = 1.53, D6m: the diffusivity measured at 6 months age by the CTH method fp: factor describing effect of pozzolanic additives on chloride threshold Kx,env: environmental factor. ↑ Comparison of laboratory and field exposure in Finnish -40C environment, for an HPC mixture with a w/b=0.42, 7% silica fume and non-air entrained Fig.2: Overview of manual structure, divided into the above sub-chapters for each of the investigated exposure type - example of results(1),(2),(3) Publications: (1) M.J. Setzer, S. Palecki: Proceedings of international conference on durability of HPC and final workshop of CONLIFE, 23-24 September 2004, Essen, Germany, ISBN 3 931 681 807 (2) CONLIFE Manual with recommendations for application of HPC & database as CD-rom, published and distributed by MC Bauchemie, September 2004 (3) CONLIFE web page: http:/fasae.ibpmw.uni-essen.de/euproject , deliverable reports 1-10