Mohammed Ahmed Abed and Eva Lubloy
Fire can severely affect concrete structures and with knowledge of the properties of materials, the damage can be assessed. Aggregate, cement matrix and their interaction are the…
Abstract
Purpose
Fire can severely affect concrete structures and with knowledge of the properties of materials, the damage can be assessed. Aggregate, cement matrix and their interaction are the most important components that affect concrete behaviour at high temperatures. The effect of incorporating recycled concrete aggregate or cementitious materials, namely, cement type and pulverized fly ash, are reviewed to provide a better understanding of their involvement in fire resistance.
Design/methodology/approach
More investigation research is needed to understand the fire resistance of such sustainable concrete that was already constructed. The present study illustrates the effect of using recycled concrete aggregate and cementitious materials on the fire resistance of concrete. To do so, a literature review was conducted and relevant data were collected and presented in a simple form. The author's selected research findings, which are related to the presents study, are also presented and discussed.
Findings
Recycled concrete aggregate enhances the concrete behaviour at high temperatures when it substitutes the natural aggregate by reasonable substitution (more than 25–30%). It also almost eliminates the possibility of spalling. Moreover, utilizing both supplementary cementitious materials with recycled concrete aggregate can improve the fire resistance of concrete. The incorporation of pulverized fly ash and slag in Portland cement or blended cement can generally keep the mechanical properties of concrete at a higher level after heating to a high temperature.
Originality/value
Recycled concrete aggregate enhances the concrete behaviour at high temperatures when it substitutes the natural aggregate by reasonable substitution (more than 25–30%). It also almost eliminates the possibility of spalling. Moreover, utilizing both supplementary cementitious materials with recycled concrete aggregate can improve the fire resistance of concrete. The incorporation of pulverized fly ash and slag in Portland cement or blended cement can generally keep the mechanical properties of concrete at a higher level after heating to a high temperature.
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Eva Lubloy, Lajos Gábor Takács, David Istvan Enczel and Zsolt Cimer
The fire safety of structures is an existing and important design aspect, which is assured by strict regulations. As a means to adhere to the strict requirements, fire protection…
Abstract
Purpose
The fire safety of structures is an existing and important design aspect, which is assured by strict regulations. As a means to adhere to the strict requirements, fire protection has become a core problem. It is particularly difficult to comply with these regulations in the case of timber, which is a combustible material. These problems could be solved by enveloping the wood in fire retardant materials. MSZ EN 1995-1-2 currently does not take into consideration the fire-retardant materials charring rate under fire exposure.
Design/methodology/approach
However, currently these fire retardants are proving to be reliable and depending on their application can achieve better reaction-to-fire classifications. During the research, the authors used five different fire-retardant materials on three different types of wood and tested their behaviours in a laboratory. When selecting them, it was important to choose the species that are most commonly used in the building industry but which have significantly different densities. Our choice fell upon spruce (360 kg/m3), Scots pine (540 kg/m3) and oak (650 kg/m3). During the tests, we examined the weight reduction and the process of burning on the specimens treated with the fire retardant material. In addition, the authors also performed tests by derivatography on both untreated and treated specimen.
Findings
The question is whether the effects of the fire retardants should be taken into consideration when calculating the extent of the burn. The Eurocode (MSZ EN 1995-1-2) does not provide any opinions. On the market, there are manufacturers who are already discussing the possibilities of reducing the burn rate during the qualification of paints. In this paper, based on the results we received, we discuss the beneficial effects of the fire retardants which can be taken into account while measuring cross-sections.
Originality/value
By using fire retardants, a high proportion of cross-sectional area gain is only possible in case of small cross-sections; therefore, it is advisable to use them here as well. This can be effective for example in many smaller cross-sections, when there is a little space and therefore requires a small cross-section. Thus, if a larger cross-section without protection is not possible, it can be replaced by a smaller cross section, treated with a fire retardant.
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The aim of the research was to investigate the effect of concrete strength on the fire resistance of structures. At first, it may seem contradictory that higher concrete strengths…
Abstract
Purpose
The aim of the research was to investigate the effect of concrete strength on the fire resistance of structures. At first, it may seem contradictory that higher concrete strengths can decrease the fire resistance of building structures. However, if the strength of the concrete exceeds a maximum value, the risk of spalling (the detachment of the concrete surface) significantly.
Design/methodology/approach
Prefabricated structural elements are often produced with higher strength. The higher concrete strengths generally do not cause a reduction in the load bearing capacity, but it can have serious consequences in case of structural fire design. Results of two prefabricated elements, namely, one slab (TT shaped panel) and one single layer wall panel, were examined. Results of the specimen with the originally designed composition and a specimen with modified concrete composition were examined, were polymer fibres were added to prevent spalling.
Findings
As a result of the experiments, more strict regulations in the standards the author is suggested including more strict regulations in the standards. It has been proved that to ensure the fire safety of the reinforced concrete structures, it is required after polymer fibres even in lower concrete strength class than prescribed by the standard. In addition, during the classification and evaluation of structures, it is advisable to introduce an upper limit of allowed concrete strength for fire safety reasons.
Originality/value
As a result of the experiments, the author suggests including more strict regulations in the standards. It has been proved that to ensure the fire safety of the reinforced concrete structures, it is necessary to require the addition of polymer fibres even in lower concrete strength class than prescribed by the standard. In addition, during the classification and evaluation of structures, it is advisable to introduce an upper limit of allowed concrete strength for fire safety reasons.
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Eva Lubloy, David Istvan Enczel, Lajos Gábor Takács, Zsolt Cimer and András Biró
Fire protection regulations are difficult to comply with in the case of wooden structures because of the fact that wood is a combustible material. The fire protection of wood can…
Abstract
Purpose
Fire protection regulations are difficult to comply with in the case of wooden structures because of the fact that wood is a combustible material. The fire protection of wood can be solved with coatings or by the application of flame retardants.
Design/methodology/approach
The standard of MSZ EN 1995‐1‐2 currently does not allow the consideration of fire retardants in case of scaling the fire load. In spite of the aforementioned, today there are many types of retardants on the market that are reliable and allow us to achieve a better fire protection classification.
Findings
The question is how sensitive a wood preservative is to a construction fault, or what would be the result of the erroneously applied fire retardant to the fire protection characteristics of timber used in constructions.
Originality/value
During the research, five different fire retardants were tested on three types of wood and their behaviour was monitored under controlled laboratory circumstances. When selecting the wood, it was important to take the wood species that are most commonly used in the construction industry, and their density should be as different as possible. During the tests, the wood preservative was applied incorrectly, modelling the following cases: applying less or more wood preservatives, and creating small and large faults.
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András Jakab, Viktor Hlavicka, Ágoston Restás and Eva Lubloy
During the building designing, it is very important to deal with the fire resistance of the structures. The designed materials for escape routes should be selected to ensure the…
Abstract
Purpose
During the building designing, it is very important to deal with the fire resistance of the structures. The designed materials for escape routes should be selected to ensure the usability of the structures until the time of escape. Planning affects the glass structures similarly, so these can also be partition walls and load bearing structures, although the latter is less applied on escape routes. The heat protection of the glasses can be improved with heat-protective foils, while fire protection is provided by gel intumescent material.
Design/methodology/approach
To research the topic of fire resistance, laboratory experiments were carried out on small-scaled glass elements with thermal protection foil at Budapest University of Technology and Economics at the Department of Construction Materials and Technologies.
Findings
Fire protection of small model specimens was tested with blowtorch fire and furnace heat load. During the experiments, six foils were tested. Single pane glass, double layered and triple glazed specimens were tested with blowtorch fire.
Originality/value
Fire protection of small model specimens was tested with blowtorch fire and furnace heat load. During the experiments, six foils were tested. Single pane glass, double layered and triple glazed specimens were tested with blowtorch fire. In case of heat-protected glazing, the foils on the “protected” side of the single pane glass do not have a fire protection effect based on blowtorch fire test. For double glassed specimens, the P35 foil has a perceptible effect, even for the requirements of the flame breakthrough (E, integrity), when the foil is placed on the inner side (position 3) of the second glass layer. The stratification of each triple glazed specimens was effective against blowtorch fire load (3 M, S4&P35), so (EI, integrity and isolation) it can meet the requirements of flame breakthrough and thermal insulation.