The influence of thermal-stressing (up to 1000°C) on the physical, mechanical, and chemical properties of siliceous-aggregate, high-strength concrete

Heap, Michael; Lavallée, Yan; Laumann, Andreas; Hess, Kai‐Uwe; Meredith, P. G.; Dingwell, D. B.; Huismann, Sven; Weise, Frank

doi:10.1016/j.conbuildmat.2013.01.020

Cited by 121 publications

(68 citation statements)

References 74 publications

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“…4 shows the porosity and pore size distribution of sacrificial concrete at ambient temperature and after exposure to 200, 400, 600, 800, and 1000 ºC. With the increase of temperature, the porosity of sacrificial concrete continually increased, which is consistent with the findings for high-strength concrete subjected to elevated temperatures [41,42]. The increase of porosity of sacrificial concrete can be attributed to the loss of water in capillary pores and hydration products [43], cracks induced by the incompatible deformation between cement paste and aggregate [39], and the channels due to the melting of polypropylene fibres in sacrificial concrete (see Fig.…”

Section: Resultssupporting

confidence: 78%

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Mechanical and thermal properties of graphene sulfonate nanosheet reinforced sacrificial concrete at elevated temperatures

Chu

Sun

Zhang

2017

Construction and Building Materials

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Progress in the field of nanomaterials presents an opportunity to improve the performance of cementitious composites via graphene or its derivatives. This paper presents an experimental study on mechanical and thermal properties of sacrificial concrete without and with graphene sulfonate nanosheets (GSNSs) during high temperature exposure. The microstructure, porosity, mechanical strengths, thermal analysis, coefficient of thermal expansion, thermal diffusivity and ablation behaviour of sacrificial concrete during exposure to various temperatures up to 1000 ºC were comprehensively investigated. Two new experimental apparatuses were developed and used to measure mechanical strengths of sacrificial concrete at elevated temperatures. It was found that the compressive strength, splitting tensile strength, thermal diffusivity and decomposition enthalpy of sacrificial concrete were increased by 12. 98-25.36%, 8.66-34.38%, 25.00-103.23% and 4.23% respectively when adding 0.1 wt% GSNSs, while the porosity and ablation velocity of sacrificial concrete were reduced by 3.01-6.99% and 4.14% respectively due to the incorporation of GSNSs.

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Section: Resultssupporting

confidence: 78%

“…Accordingly, the mechanical properties of sacrificial concrete may degrade under these circumstances [41]. The loss of water in hydration products may lead to shrinkage of concrete [50].…”

Section: Thermal Analysismentioning

confidence: 99%

Mechanical and thermal properties of graphene sulfonate nanosheet reinforced sacrificial concrete at elevated temperatures

Chu

Sun

Zhang

2017

Construction and Building Materials

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“…The presence of these macrofractures increases permeability (by a factor of 2) and also appears deleterious to elastic wave propagation (all the three samples containing mesofractures have low elastic wave velocities, although we cannot separate the influence of meso-and microcracks on the velocities of these samples). Further, elastic waves are useful for the detection of cracks in rock and concrete (Chaki et al 2008;Heap et al 2013), and a decreased elastic wave velocity correlates well to more permeable media which is observed by the three outlying, higher permeability, lower elastic wave velocity samples.…”

Section: Permeability and Acoustic Velocitiesmentioning

confidence: 99%

Physical property relationships of the Rotokawa Andesite, a significant geothermal reservoir rock in the Taupo Volcanic Zone, New Zealand

et al. 2014

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Background: Geothermal systems are commonly hosted in highly altered and fractured rock. As a result, the relationships between physical properties such as strength and permeability can be complex. Understanding such properties can assist in the optimal utilization of geothermal reservoirs. To resolve this issue, detailed laboratory studies on core samples from active geothermal reservoirs are required. This study details the results of the physical property investigations on Rotokawa Andesite which hosts a significant geothermal reservoir. Methods:We have characterized the microstructure (microfracture density), porosity, density, permeability, elastic wave velocities, and strength of core from the high-enthalpy Rotokawa Andesite geothermal reservoir under controlled laboratory conditions. We have built empirical relationships from our observations and also used a classical micromechanical model for brittle failure. Further, we compare our results to a Kozeny-Carman permeability model to better constrain the fluid flow behavior of the rocks. Results: We show that the strength, porosity, elastic moduli, and permeability are greatly influenced by pre-existing fracture occurrence within the andesite. Increasing porosity (or microfracture density) correlates well to a decreasing uniaxial compressive strength, increasing permeability, and a decreasing compressional wave velocity. Conclusions:Our results indicate that properties readily measurable by borehole geophysical logging (such as porosity and acoustic velocities) can be used to constrain more complex and pertinent properties such as strength and permeability. The relationships that we have provided can then be applied to further understand processes in the Rotokawa reservoir and other reservoirs worldwide.Keywords: Geothermal; Uniaxial compressive strength; Permeability; Physical properties; Elastic modulus; Microstructure BackgroundFractures on multiple scales are the dominant control on fluid flow in most geothermal systems worldwide. Geothermal environments are prone to variable heat fluxes, dynamic fluid flow regimes, and active tectonics which impact the physical and mechanical properties of the reservoir rocks in which they are hosted. The influence of such a dynamic environment can render the host rocks highly altered, fractured, and microstructurally complex. As a result, the empirical correlation of physical properties to

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“…Jacobsen and Sellevold 1996;Hearn and Morley 1997;Hearn 1997;Edvardsen 1999;Van der Zwaag 2007;Homma et al 2009;Qian et al 2009;Yang et al 2009). While Heap et al (2013) showed that the water permeability of concrete increases significantly with the progress of fracturing, it is also possible that the sealing of existing fractures and pores affects the permeability of concrete. So far, various reports on the fracture sealing of concrete have been published (e.g., Jacobsen and Sellevold 1996;Hearn and Morley 1997;Hearn 1997;Edvardsen 1999;Reinhardt and Jooss 2003;Granger et al 2007; Van der Zwaag 2007;Homma et al 2009;Qian et al 2009;Yang et al 2009;Ahn and Kishi 2010;Wu et al 2012;Fukuda et al 2012;Fukuda et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Observation of fracture sealing in high-strength and ultra-low-permeability concrete by micro-focus X-ray CT and SEM/EDX

et al. 2014

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Fracture sealing by precipitation is known to occur in high-strength and ultra-lowpermeability concrete (HSULPC) immersed in water. Because a high ability to retard radionuclide migration is required for HSULPC, understanding both the sealing process and the composition of sealing deposits is important to identify optimum conditions for significant sealing. In this study, sealing of a macro-fractured HSULPC specimen with initial aperture of approximately 0.1 mm was investigated in simulated seawater over 49 days. The composition of sealing deposits at 49 days after immersion was clarified by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDX), and the progress of sealing during the 49 days was clarified by image analysis with micro-focus X-ray computed tomography (X-rayCT). Both the SEM/EDX and X-rayCT results showed that significant sealing was attained only near the outermost part of the specimen. The SEM/EDX results showed that a thin brucite layer formed on the entire specimen surface over which significant precipitation of calcium carbonate occurred and sealed the macro-fracture only near the outermost part of the specimen. The X-rayCT results indicated that the amount of sealing deposits in the macro-fracture (P seal ) reached 70 % in the mostly sealed region at 49 days and the rate of change in P seal became maximum (3.7 % day -1 ) during 7-21 days after immersion, then decreased. In conclusion, Revised_Manuscript Click here to download Manuscript: IJF_manuscript_FRAC_Rev1.doc Click here to view linked References 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 the findings in this study represent an important clue in the search for optimum conditions to achieve fracture sealing in HSUPLC.

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The influence of thermal-stressing (up to 1000°C) on the physical, mechanical, and chemical properties of siliceous-aggregate, high-strength concrete

Cited by 121 publications

References 74 publications

Mechanical and thermal properties of graphene sulfonate nanosheet reinforced sacrificial concrete at elevated temperatures

Mechanical and thermal properties of graphene sulfonate nanosheet reinforced sacrificial concrete at elevated temperatures

Physical property relationships of the Rotokawa Andesite, a significant geothermal reservoir rock in the Taupo Volcanic Zone, New Zealand

Observation of fracture sealing in high-strength and ultra-low-permeability concrete by micro-focus X-ray CT and SEM/EDX

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