Verification of the Influence of Loading and Mortar Coating Thickness on Resistance to High Temperatures Due to Fire on Load-Bearing Masonries with Clay Tiles.

Rodrigo P De Souza,Vinícius Muller De Mello,Augusto M Gil,Roberto Christ,Gustavo L Prager,Fernanda Pacheco,Bernardo F Tutikian

doi:10.3390/ma12223669

Rodrigo P De Souza, Vinícius Muller De Mello + Show 5 more

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https://doi.org/10.3390/ma12223669

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Abstract

Masonry has been widely used as a construction method. However, there is a lack of information on its fire behavior due to the multitude of variables that could influence this method. This paper aimed to identify the influence of loading and mortar coating thickness on the fire behavior of masonry. Hence, six masonries made of clay tiles laid with mortar were evaluated. The mortar coating had a thickness of 25 mm on the face not exposed to high temperatures, while the fire-exposed face had thicknesses of 0, 15, and 25 mm. For each mortar coating thickness, two specimens were tested, with and without loading of 10 tf/m. The real-scale specimens were subjected to the standard ISO 834 fire curve for four hours, during which the properties of stability, airtightness, and thermal insulation were assessed. Results showed that loaded specimens yielded smaller deformations than unloaded ones. Samples that lacked mortar coating on the fire-exposed face underwent fire resistance decrease of 27.5%, while the ones with 15 mm decreased by 58.1%, and the ones with 25 mm decreased by 41.0%. As mortar coating thickness increased, the plane deformations decreased from 40 mm to 29 mm and the thermal insulation properties of the walls improved significantly. For specimens with mortar coating thickness of 25 mm, the load application resulted in a reduction of 23.8% of the thermal insulation, while the unloaded specimen showed a decrease of 43.3%, as well as a modification of its fire-resistance rating.

Highlights

When fire strikes a structural masonry building, it endangers the building’s physical structure and the life of its occupants [1]
The experimental procedure results led to the conclusion that the unloaded sample that achieved the best performance with respect to the fire-resistance rating (FRR) was Wall 5 (W5) (25 mm of coating on both faces), with an fire-resistance ratingsratings (FRR) of 240 min, namely, meeting the requirements of airtightness, structural stability and thermal insulation within this timespan
The loaded sample that showed the best performance for FRR was Wall 6 (W6) (25 mm of coating on both faces), meeting the requirements of structural stability and airtightness while losing its thermal insulation at 221 min

Summary

Introduction

When fire strikes a structural masonry building, it endangers the building’s physical structure and the life of its occupants [1]. The thermal action from fire conditions is described by radiation and convection heat transfer mechanisms, whereas the heat from the fire can spread by conduction, convection, and radiation [3]. Several technical standards specify conditions for safe building operations and even include exceptional events such as fires [4]. There are functional safety requirements concerning fire prevention and extinguishing, ways to Materials 2019, 12, 3669; doi:10.3390/ma12223669 www.mdpi.com/journal/materials. Materials 2019, 12, 3669 limit fire spread and prevent damages and even collapse, along with safe user evacuation methods and safe access routes for rescue teams and firefighters [5,6].

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