Capillary suction and chloride migration in fire exposed concrete with PP-fibre

• Annually, several concrete structures, such as buildings, bridges, parking garages, tunnels, etc. are exposed to fires. Many fires are small, for example single car fires in tunnels. These fires do not affect the load carrying capability of the concrete structure and thus minor or no reparations are required. In modern concrete for civil engineer applications the use of Polypropylene fibres (PP-fibre) to reduce fire spalling is growing. Some studies have been carried out which indicate that the use of PP-fibres will not affect the durability of the concrete. But in case of a fairly moderate fire exposure, a fire exposure that does not lead to structural damage, the PP-fibres can potentially lead to reduced durability. During low intensity fires or at long distances downstream a large fire in a tunnel the PP-fibres melts and form channels in the concrete. After such degradation of the PP-fibres it is plausible that accelerated damage may occur when moisture, de-icing salts and carbon dioxide can more easily penetrate the concrete. In this experimental study the chloride migration and the capillary suction are studied in moderately heated concrete containing PP-fibres. The chloride migration tests were conducted with heated samples with and without PP-fibres. The capillary suction tests were even conducted with different fibre contents. As a reference the results are compared with results from unheated concrete. The aim of the project is to define whether or not measures have to be taken to repair concrete structures after small fires and at long distances downstream from large fires in tunnels. If the durability is affected the costs and consequences of not repairing and refurbishing after the fire can potentially be very high especially after a fires in very long tunnel.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Samhällsbyggnadsteknik -- Husbyggnad (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Civil Engineering -- Building Technologies (hsv//eng)

Nyckelord

Capillary suction

Chloride migration tests

Civil engineers

Deicing salts

Experimental studies

Fibre content

Fire exposed

Fire exposures

Load carrying capability

Low-intensity

Polypropylene fibres

Small fire

Structural damages

Publikations- och innehållstyp

ref (ämneskategori)

kon (ämneskategori)