Fire spalling of concrete
(English)Manuscript (preprint) (Other academic)
When occurring fire spalling of concrete is a phenomenon that reduces the fire resistance of fire exposed members by loss of cross section. The reduction of strength by the presence of moisture is a main component in the fire spalling phenomena during fire exposure from one side. Without including this effect the function of an addition of polypropylene fibres could not be fully explained. In many experiments the crack leading to the formation of a flaking off occurs at a temperature substantially lower than the temperatures where the pressure from saturated steam is high enough to be the main driving force for the phenomenon. Also no simple correlation between measured pore pressures and the fire spalling phenomenon has been found. The present study made by testing the compressive strength of small mortar specimens shows that a specimen boiled for 10 minutes has only 64% of the strength of a dry specimen. This result highlights the substantial strength reducing effect of the presence of moisture at elevated temperatures independent of the pore pressure. The presence of polypropylene fibres reduces the moisture content around the critical zone.
fire spalling, concrete, polypropylene fibres
IdentifiersURN: urn:nbn:se:kth:diva-128373OAI: oai:DiVA.org:kth-128373DiVA: diva2:647382
QS 20132013-09-112013-09-112013-09-11Bibliographically approved