Study on mechanism of thermal spalling in concrete exposed to elevated temperatures

Fu, Y.F.; Li, Lianchong

doi:10.1617/s11527-010-9632-6

Cited by 123 publications

(65 citation statements)

References 19 publications

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“…The research literature identifies pore pressure and thermal stress as two key mechanisms responsible for explosive spalling [20,21,22,23,24,25,26,27]. Pore pressure spalling is due to vaporisation of free, interlayer and/or chemically combined water causing a rapid increase in pore pressures which exceeds the tensile strength of the material.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

The effect of concrete composition on laser scabbling

Peach

Petkovski

Blackburn

et al. 2016

Construction and Building Materials

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Laser concrete scabbling is the process by which the surface layer of concrete may be removed through the use of a low power density laser beam. The main aim of this investigation was to establish relationships between laser interaction time and volume removal for a wide range of material compositions, including different w/b ratios, binder compositions (OPC/PFA), aggregate/binder ratios and coarse aggregate sizes. The results show that 25% replacement of ordinary Portland cement with pulverised fuel ash and/or a reduced water/binder ratio improves the efficiency of scabbling of cement pastes. Mortars and cement pastes were seen to scabble at a constant rate, whereas concretes experienced a peak rate, after which volume removal reduced dramatically. Basalt aggregate concrete was less susceptible to laser scabbling than limestone aggregate concrete. The effects of composition on the mechanisms which drive laser scabbling are discussed. It is suggested that pore pressure spalling governs behaviour in cement pastes, and thermal stress spalling is more dominant in mortar specimens. The driving force responsible for laser scabbling of concretes is developed within the mortar.

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Section: Discussion Of Resultsmentioning

confidence: 99%

The effect of concrete composition on laser scabbling

Peach

Petkovski

Blackburn

et al. 2016

Construction and Building Materials

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“…The spalling of concrete cover can expose vital structural reinforcement. The topic has received much attention in the fire safety sciFire Performance of Sustainable Recycled Concrete Aggregates ence community over the last 5 years [58][59][60][61], with three major studies on this subject in the last year being published [51,62,63]. Even in conventional concrete it is not fully understood.…”

Section: Knowledge Gapsmentioning

confidence: 99%

Fire Performance of Sustainable Recycled Concrete Aggregates: Mechanical Properties at Elevated Temperatures and Current Research Needs

et al. 2015

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The materials used for the construction of buildings are changing. There are now many sustainability drivers for developing novel green construction materials. An emerging material used for building construction is concrete with conventional coarse aggregates substituted as recycled concrete aggregates (RCA). This is a form of sustainable concrete. A finite number of buildings (>10) with this material have been constructed in North America, Europe and Asia. However; to help facilitate wide spread use and development of sustainable concrete with RCA, there is purpose in considering this material's at-elevated temperature (in-fire) mechanical properties. To date, this topic has seen limited research attention as it is difficult to study. The study herein considered the mechanical properties of conventional and sustainable concrete with RCA. The only difference between the conventional and the sustainable concrete mixes was the mass proportion of a conventional natural coarse aggregate, Limestone, which had been substituted with coarse RCA (at replacement proportions of 0%, 30% and 100%). Both the ambient and elevated temperature mechanical properties were considered with compressive mechanical tests using an innovative optical technology for strain measurement. Based on the analysis performed, a proportional decrease in retained strength and elasticity of concrete at-elevated temperature with increasing RCA content was observed. For example both mechanical properties showed a 0.2% decrease in retained value for every 1% RCA increase at 500°C. In addition the modelling parameter of Poisson ratio appeared to be influenced by the heat imposed and the aggregate type contained within the concrete. For example at 500°C, this parameter showed an 73% increase for concrete samples with only Limestone aggregate and a 15% decrease for samples with only RCA (of mixed origin primarily Siliceous). This paper concludes with highlighting current knowledge gaps and research needs that when addressed could help improve the facilitation of using sustainable concrete's with RCA in construction of buildings.

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“…Significant problem is, next to the decrease of mechanical properties, the explosive spalling described in several studies and practical experiences. [2][3][4] Stonis et al 5 tried to replace silica fume by metakaolin (MK) in heat-resistance concrete and established that ultimate compressive strength after temperature loading at 800°C and 1200°C is higher by 5% and 10%, respectively (compared to silica fume). It has been shown by Morsy and Shebl 6 that appropriate addition of MK improves final resistance against sudden thermal shock.…”

Section: Introductionmentioning

confidence: 99%

Fracture characteristics of refractory composites containing metakaolin and ceramic fibers

Holčapek

Reiterman

Konvalinka

2015

Advances in Mechanical Engineering

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The aim of present article is to describe influence of composition of refractory composites on its response to gradual thermal loading. Attention was focused on the impact of ceramic fibers and application of metakaolin as an aluminous cement supplementary material. Studied aluminate binder system in combination with natural basalt fine aggregates ensures sufficient resistance to high-temperature exposure. Influence of composition changes was evaluated by the results of physical and mechanical testing-compressive and flexural strength, bulk density, and fracture energy were determined on the different levels of temperature loading. Application of ceramic fibers brought expected linear increase of ductility in studied composites. Metakaolin replacement showed the optimal dose to be just about 20% of aluminous cement weight.

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Study on mechanism of thermal spalling in concrete exposed to elevated temperatures

Cited by 123 publications

References 19 publications

The effect of concrete composition on laser scabbling

The effect of concrete composition on laser scabbling

Fire Performance of Sustainable Recycled Concrete Aggregates: Mechanical Properties at Elevated Temperatures and Current Research Needs

Fracture characteristics of refractory composites containing metakaolin and ceramic fibers

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