Frost Durability of Low-Clinker Binders

Date This project started on 01 October 2016

Status This project is Ongoing

Authors

Lund University, SE
NTNU, NO

Objectives

Frost deterioration of concrete is an important durability issue for concrete structures exposed to high humidity, frost and deicers. Today when the variety of binder compositions is rapidly increasing, it is more important than ever to understand the mechanism behind the deterioration to be able to obtain frost durable structures.

The combination of high degree of saturation and low temperatures can result in both surface scaling and internal cracking. Frost damage can lead to loss of concrete cover and thus reduced protection of the reinforcement and possible loss of bearing capacity. Frost damage in form of cracking facilitates ingress of aggressive substances and thus other deterioration mechanisms as well. The degree of deterioration depends on the surrounding environment such as temperature, relative humidity, precipitation, deicers, and on the materials properties such as permeability, air void structure and mechanical properties.

Long-term experience shows that concrete structures with high amounts of Portland clinker and various air entraining admixtures can be durable. Field exposure investigations confirm that the existing test methods can usually predict the performance of Portland cement concrete. However, with the increasing substitution of Portland clinker, concrete becomes more sensitive to variations in execution (e.g. air entrainment, curing) and to ageing (e.g. carbonation), which can lead to reduced resistance to salt frost scaling of the hardened concrete. To solve these challenges improved understanding of basic mechanisms is needed.

The research will combine modelling of salt frost deterioration with experimental characterisation of concrete properties that are significant in salt frost degradation such as ice formation, permeability, air void structure and surface strength.

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