Mechanical property and thermal damage factor of limestone at high temperature

Yang, Jian; Fu, Li; Zhang, Weiqiang; Wang, Zhiwei

doi:10.1016/j.ijrmms.2019.03.012

Cited by 77 publications

(26 citation statements)

References 44 publications

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“…This is coherent with other works [15,52], and produces a gradual decrease in the elastic modulus [20]. A decrease in ultrasound velocity was registered at 400º C due to thermal cracking, as reported for limestone by different authors [16][17][18]53]. This fact is consistent with initial trans-granular fissures and porosity observed using SEM at 400º C (Figure 2b).…”

Section: Discussionsupporting

confidence: 91%

“…Some authors did not report any induced effect of temperature on the rocks [55,56] or describe a decreasing trend [11,15,20]. However, Yang et al [53] suggest that the different instrumental devices, methods, or even the diversity of samples, could lead to such scattered results. This study throws light on this aspect and advances in the analysis of this mechanical parameter using both slow and rapid cooling methods.…”

Section: Discussionmentioning

confidence: 99%

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Micro and macro-structural effects of high temperatures in Prada limestone: Key factors for future fire-intervention protocols in Tres Ponts Tunnel (Spain)

Martínez-Ibáñez

Garrido

Signes

et al. 2021

Construction and Building Materials

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Temperature and cooling methods strongly affect the stability of tunnels drilled in rock masses and so condition interventions for fire emergencies. Samples from two horizontal boreholes drilled in 'Prada' limestone during the design stage of the Tres Ponts Tunnel in the Catalan south Pyrenean zone (Spain) are heated from 105 to 600º C, and subsequently cooled with air or water to simulate fire extinguishing interventions. Changes in chemical composition and microstructure, physical properties (open porosity, volume, dry total weight, P and S-wave velocity), and mechanical properties (uniaxial compressive strength, elastic modulus, and Poisson's ratio) are analysed. Rock weakening is observed even at low temperatures (T<300º C). The influence of the cooling method appeared at intermediate temperatures of 300-400º C and open porosity, P and S-wave velocities, and elastic modulus show greater variation for water-cooled samples. A temperature of 500º C is of paramount importance for 'Prada' limestone as it leads to a dramatic increase in porosity and a notable decrease in P and S-wave velocities under both cooling methods. Trans-granular micro-crack progression is observed at 500º C using scanning electron microscope (SEM), and water-cooled samples show a greater loss in uniaxial compressive strength (UCS), and this is due to micro-crack connections and growing fissures. Thermal damage at 600º C is also greater when samples are quickly cooled. An ANOVA and a simple regression analysis are performed to discard the influence of the natural location of the borehole samples in the obtained experimental results. Finally, correlations to predict UCS and elastic modulus from volume, open porosity, and P-wave velocity after thermal treatment are proposed using simple exponential and potential functions to help make preliminary decisions after a tunnel fire. These predictive results on the effects of fire on Prada limestone will be considered for the definition of future fire intervention protocols in the Tres Ponts Tunnel.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Micro and macro-structural effects of high temperatures in Prada limestone: Key factors for future fire-intervention protocols in Tres Ponts Tunnel (Spain)

Martínez-Ibáñez

Garrido

Signes

et al. 2021

Construction and Building Materials

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“…Local thermal stress concentrations occur between mineral particles of different nature, due to mismatch in thermal expansion coefficients, thus increasing microcracking. Such effect has been reported in limestones by different authors (Liu and Xu 2013;Zhang et al 2017b;Villarraga et al 2018;Yang et al 2019), and the range of temperatures of 400 to 500 °C configures a threshold for thermal cracking (Meng et al 2020). For all above, we will discuss the role of organic matter and pyrite presence.…”

Section: Discussionmentioning

confidence: 60%

“…The maximum strength slowly decreased while the peak strain continuously increased, elastic modulus declined quickly, Poisson's ratio dropped suddenly, and the hardness decreased from mid-hard to soft. Recently, research correlated physical and mechanical properties to define a thermal damage factor (Yang et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Temperature-Induced Explosive Behaviour and Thermo-Chemical Damage on Pyrite-Bearing Limestones: Causes and Mechanisms

et al. 2020

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In this investigation, two different varieties of 'Prada' limestones were studied: a dark grey texture, bearing quartz, clay minerals, organic matter and pyrites, and a light grey texture with little or no presence of such components. We have observed two effects of different intensity when heating the dark texture from 400º C: i) the explosion of certain samples and ii) greater thermal damage than in the light grey texture. Chemical and mineralogical composition, texture, microstructure, and physical properties (i.e. colour, open porosity, P and S-wave velocity) have been evaluated at temperatures of 105, 300, 400 and 500º C in order to identify differences between textures. The violence of the explosive events was clear and cannot be confounded with ordinary splitting and cracking on thermally-treated rocks: exploded samples underwent a total loss of integrity, displacing and overturning the surrounding samples, and embedding fragments in the walls of the furnace, whose impacts were clearly heard in the laboratory. Thermogravimetric results allowed the identification of a process of oxidation of pyrites releasing SO 2 from 400º C. This process jointly with the presence of micro-fissures in the 2 dark texture, would cause a dramatic increase in pore-pressure, leading to a rapid growth and coalescence of microcracks that leads to a process of catastrophic decay in rock integrity. In addition to the explosive events, average ultrasound velocities and open porosity showed a greater variation in the dark grey texture from 400º C. That results also points towards a significant contribution of oxidation of pyrites on the thermochemical damage of the rock, among other factors such as the pre-existence of microfissuresand the thermal expansion coefficient mismatch between minerals. Implications in underground infrastructure and mining engineering works are critical, as the explosive potential of pyrite-bearing limestones bear risk for mass fracturing and dramatic strength decay from 400º C. Moreover, SO 2 released has harmful effects on health of people and the potential to form acid compounds that corrode materials, shortening their durability and increasing maintenance costs.

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“…25 To improve the understanding of mechanical properties of rock after thermal treatments, many relevant experiments have been performed previously. The strength and deformation parameters of thermally damaged rock specimens under uniaxial compression, [26][27][28][29] Brazilian splitting test, [30][31][32][33] three-point bedding test, 34,35 conventional triaxial compression, [36][37][38] fatigue loading, 39 triaxial unloading of confining pressure, 40 triaxial creep loading 41 and dynamic impact 42 have been investigated. These studies revealed that the mechanical properties of rocks evolved nonlinearly with the increase in temperature.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on fracture behaviour of three‐flawed sandstone specimens after high‐temperature treatments

Huang

Yang

Dong

2020

Fatigue Fract Eng Mat Struct

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The crack coalescence of rocks significantly affects the stability of rock engineering, and extensive studies have been performed on preflawed rock specimens without thermal treatment. However, the fracturing behaviour of preflawed specimens after thermal treatment has not been investigated comprehensively. In this study, three‐flawed sandstone specimens with different flaw inclinations after high‐temperature treatments were tested under uniaxial compression. Photographic, acoustic emission and digital image correlation techniques were used to investigate the crack initiation, propagation and coalescence behaviour. Experimental results show that the peak strength, elastic modulus and peak strain of the three‐flawed specimens were lower than those of intact specimens and that they gradually recovered with increasing flaw angle. The peak strength and elastic modulus first increased and then decreased, whereas the peak strain increased with temperature. Noncoalescence, indirect coalescence and direct coalescence were three patterns observed between the two adjacent pre‐existing flaws. Finally, the mechanism of high temperature in alteration of the mechanical properties of sandstone was revealed through microobservations.

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Mechanical property and thermal damage factor of limestone at high temperature

Cited by 77 publications

References 44 publications

Micro and macro-structural effects of high temperatures in Prada limestone: Key factors for future fire-intervention protocols in Tres Ponts Tunnel (Spain)

Micro and macro-structural effects of high temperatures in Prada limestone: Key factors for future fire-intervention protocols in Tres Ponts Tunnel (Spain)

Temperature-Induced Explosive Behaviour and Thermo-Chemical Damage on Pyrite-Bearing Limestones: Causes and Mechanisms

Experimental study on fracture behaviour of three‐flawed sandstone specimens after high‐temperature treatments

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