Presented at the XXIV Nordic Concrete Research Symposium in Stockholm, August 17-19, 2022.

1. MESLA
Management and Extension of Service Life of
infrastructures affected by Alkali‐silica reaction
Jan Lindgård (SINTEF)
Terje Kanstad (NTNU)
Bård Pedersen and Eva Rodum (NPRA)
XXIV NCR Symposium 2022

2. Background
• R&D focus in Norway (1990-2020)
 Overview of the ASR problem – reactive aggregates
 Avoid ASR in new structures
o Develop reliable test methods and flexible ASR regulations
o Performance testing (active in RILEM)
Main reactive
aggregates

3. Background
• After 2010: More focus on management of
concrete structures with ASR
 Many large concrete dams with ASR
o But, no large R&D projects initiated
 Several thousand concrete bridges with ASR
o Increasing problem
o Several R&D projects on maintenance and structural
consequences initiated by the NPRA

4. • Visually negative
• Structural consequences
 "Extra load" (due to the expansion)
 Reduced material properties
 "Double negative"
o Reduced capacity?
• Initialize other deterioration mechanisms
 Frost damage? (increased moisture content, less protective air voids)
 Rebar corrosion?
Consequences of ASR
Photo: Jan Lindgård

5. R&D projects related to assessment of bridges (2012-2022)
• Lack of knowledge internationally
 How to manage and reassess ASR affected structures?
 Unsure decisions (over-conservative or underestimating the ASR impact?)
• R&D co-operation nationally (and internationally)
 Project owner: Norwegian Public Roads Administration (NPRA)
 Co-operation with NTNU, SINTEF, ULaval, …..…
 17 MSc students and 2 PhD students

6. R&D projects related to assessment of bridges (2012-2022)
• Main NPRA projects (incl. ASR)
 “Durable Structures” (2012-2015)
 “Improved Bridge Maintenance” (2017-2022)
o “ARKON” (2018-2022)
 Deliverables
o Field testing programs (surface treatment; expansion; RH)
o Guidelines (inspection; lab-testing; structural analysis)
o Test results
Cracking Index Laser scanning DRI SDT

7. MESLA (2021-2025)
• Participants
 Owner:
o NTNU Dep. Of Structural Engineering
 Partners:
o Bridge owners: NPRA, BaneNOR and Trøndelag County
o Consultant: Norconsult
o Research institutes: SINTEF (Community and Narvik)
o International univ.: Laval & Ottawa (Canada) and Gustave Eiffel (France)
• Budget
 Norwegian Research Council: 12 MNOK (incl. 1 PhD)
 Partners (in-kind work): 3 MNOK

8. MESLA (2021-2025)
• Main technical objectives
 Establishing basis for reliable assessments of the structural performance
of concrete structures with progressing ASR
 Assess the consequences of the ASR-induced damage
• Sub-objectives: Clarifying many research questions
1. How to collect reliable field data (sampling and monitoring)?
o Extent of damage and local variations?
o “Expansion-up-to-date” of various structural members?

9. MESLA (2021-2025)
• Sub-objectives: Clarifying many research questions
2. Which lab. analyses can be performed to give input to the structural assessment?
o Extent of internal cracking?
• Link to “expansion-up-to-date”?
• Link to mechanical degradation?
3. “Residual expansion” over the remaining lifetime?
o Any reliable test methods?
4. How to utilize results from field and lab. for assessing the structural performance?
o Material models?
5. How to evaluate the consequences of expansion and damage to comply with the
serviceability, durability, and regulatory safety of the structure?

10. MESLA (2021-2025)
WP3: Structural strength analyses
o PhD study
o Incl. sophisticated full non-linear FEM analysis
o Verification of the project results
WP4: Communication/publishing, adm.
WP2: Laboratory testing
o Incl. SDT and DRI
WP1: Field survey and monitoring
• Organization

11. MESLA (2021-2025)
• Case studies and demonstrators (verification)
• Since 1990: >100 bridges incl. as cases in Norw. ASR projects
 Field surveys and lab. analyses
 A few monitored (exp. and RH)
• Case studies in the MESLA project
 To be selected in co-operation with the bridge owners
 2022: Tromsø bridge
o Field survey and some lab. analyses performed
o Monitoring of joints and RH initiated
o Laser scanning performed – planned to be repeated
o 3 Master thesis completed

12. Technology for a better society Thank you!