Management and Extension of Service Life of infrastructures affected by Alkali-silica reaction (MESLA)

Over the last decades, Alkali-silica reaction (ASR) has become a deterioration mechanism of great concern for Norwegian concrete structures, affecting important national transport infrastructure such as road - and railway bridges. The research community has reached an advanced knowledge on the deterioration mechanisms and has the necessary tools to avoid ASR in new structures. However, only limited research has been performed on management of existing structures with ongoing ASR, and there is still a lack of knowledge, both nationally and globally. The overall aim of the R&D project "MESLA" ("Management and Extension of Service Life of infra-structures affected by Alkali-silica reaction", 2021-2025) is to build up new knowledge on how to manage and maintain existing ASR-affected structures in a technical, economic and environmental beneficial way, and verify how this knowledge can be applied to ensure structural safety and extend the service life of existing bridges. The project is managed by NTNU and SINTEF. Other partners are the Norwegian Public Road Administration, Bane NOR, Trøndelag County Council, SINTEF Narvik, Norconsult and three leading international universities (Laval, Ottawa and Gustave Eiffel). The bridge owners will secure access to relevant bridges with ASR for field survey and monitoring (WP1) and sampling for subsequent relevant laboratory analyses (WP2). In WP3 "Structural strength analysis", material models for ASR-affected concrete will be established, and structural analyses (FEM analysis) will be carried out for selected examined bridges ("demonstrators"). The main project findings will be published (WP4) in international peer-reviewed journals, presented at relevant conferences, and spread and utilised by participation in international and national committees. Hopefully, the MESLA project will contribute to an improved system for management of our concrete bridges of great importance for the owners and the community.

Over the last decades, Alkali-silica reaction (ASR) has become a deterioration mechanism of great concern for Norwegian concrete structures, affecting important national transport infrastructure such as road and railway bridges. The research community has reached an advanced knowledge on the deterioration mechanisms and has the necessary tools to avoid ASR in new structures. However, only limited research has been performed on management of existing structures with ongoing ASR, and there is still a lack of knowledge, both nationally and globally. The overall aim is to build up new knowledge on how to manage and maintain existing ASR-affected structures in a technical, economical and environmental beneficial way, and verify how this knowledge can be applied to ensure structural safety and extend the service life of existing bridges. The MESLA project comprises four parts. In "WP1 Field survey and monitoring", ASR-induced expansion indicators as cracks and deformations will be measured and monitored, and samples will be extracted from existing bridges. In "WP2 Laboratory testing", drilled cores will be tested by different methods to give information on the current concrete state such as expansion, stiffness and strength properties. The prediction of the future expansion will be based on field measurements and accelerated testing of drilled cores. In "WP3 Structural strength analysis", material models for ASR-affected concrete will be established, and structural analyses will be carried out for selected examined bridges. The principle of “levels of approximation” will be followed, meaning that various alternative models with different levels of sophistication will be used. In "WP 4 Dissemination, meetings and project management", the main project findings will be shared with the entire project team, published in international peer-reviewed journals, presented at relevant conferences, and spread and utilised by participation in international and national committees.