Course 2 - Dams affected by concrete swelling reactions: diagnosis, prediction and rehabilitation
LNEC, Library
About the Course
Speakers
The concrete swelling reactions (alkali-silica reaction – ASR – and delayed ettringite formation – DEF) can induce significant deformations on structures, sometimes causing serious cracking, equipment misalignment, and even leakage. These reactions also induce a decrease in tensile strength and the elasticity modulus and, in some cases, a reduction in the compressive strength. Dams and hydroelectric plants are particularly vulnerable to these phenomena, as they are fed by the water. In dams, increased long-term damage (cracking) and irreversible crest displacements are observed, potentially affecting stability and spillway gates clearances. In hydroelectric plants, deformations can affect turbines and generators’ clearances and cause damage to the powerhouse superstructure.
This one-day short course will provide owners and practitioners with a concise, rigorous and comprehensive view of the swelling phenomena and current methods for its management in major structures. In particular: a) chemo-physical nature of the reactions; b) diagnosis and prognosis test methods; c) monitoring and analysis, including the main aspects of the finite element modelling; and d) management and rehabilitation of the affected dams.
Participants will receive a comprehensive set of notes, articles and documentation.
António Lopes Batista
Principal Researcher, LNEC
António Santos Silva Senior Researcher, LNEC
Olivier Chulliat Specialist,
EDF
João Custódio
Senior Researcher, LNEC
Ivo Figueiredo Dias Assistant Researcher, LNEC
Final Programme
08:30 – 09:00 – Registration
09:00 – 10:30 – General framework of the structural effects of concrete swelling reactions in dams
António Lopes Batista (LNEC, Portugal)
Macroscopic evidence of concrete swelling
Factors influencing concrete swelling
Swelling development over time and associated damage
Monitoring and management
Dams affected worldwide
10:30 – 11:00 – Coffee break
11:00 – 12:30 – Prevention, diagnosis and prognosis of concrete swelling reactions
João Custódio, António Santos Silva (LNEC, Portugal)
Concrete swelling reactions (ASR and DEF)
Prevention of ASR and DEF in new structures (existing frameworks and test methods)
Diagnosis of ASR and DEF in existing structures (laboratory test methods)
Prognosis of ASR and DEF in existing structures (laboratory test methods)
12:30 – 14:00 – Lunch
14:00 – 16:00 – Modelling of concrete swelling in dams
Ivo Figueiredo Dias (LNEC, Portugal)
Concrete swelling as a prescribed strain
Influence of creep, temperature, moisture and stress field
Cracking effects
External and internal confinement
Use of the finite element method for analysis
Practical examples
16:00 – 16:30 – Coffee break
16:30 – 18:00 – Rehabilitation techniques in dams damaged by concrete swelling
Olivier Chulliat (EDF, France)
Restore the concrete continuity
Concrete replacement
Impervious membranes
Passive and prestressing reinforcement
Slot cuts
Example of Chambon dam (France)