Thermal Cracking Behavior Research Articles

Research on the dynamics and mechanism of thermal cracking of coal-based endothermic hydrocarbon fuels

Thermal cracking of endothermic hydrocarbon fuels (EHF) plays an important role in the endothermic process when the fuel temperature exceeds the supercritical temperature. To gain a deeper understanding of the thermal cracking behavior of EHF, this work discusses the thermal cracking law and reaction mechanism of coal-based EHF at different temperatures through static thermal cracking experiments, and establishes a total molecular reaction dynamics model containing 34 species and 24-step reactions based on product distribution. The results show that in the temperature range of 450℃ to 500℃, the gas phase yield of the fuel increases linearly from 8% to 56%, and the conversion rate reaches up to 96.1%. The kinetic reaction of thermal cracking conforms to the primary kinetic equation, the cracking rate constant k is between 1.08×10-4~7.92×10-4s-1, the activation energy Ea=184.47±11.5kJ∙mol-1, and the precursor factor lnA=21.61±3.0. Gas phase products include hydrogen, methane, ethane, ethylene, propane and butane. Liquid phase products include paraffins, alkyldecahydronaphthalenes and aromatic hydrocarbons. As the cracking depth increases, the degree of fuel branching first increases and then decreases, up to 0.33. Paraffins and alkyldecahydronaphthalenes are gradually converted into olefins, cyclic olefins, benzene, naphthalene, indene, fluorene and pyrene and other compounds. Based on the product distribution, the reaction mechanism of thermal cracking of coal-based EHF is speculated to include single-molecule β-cracking, bimolecular F-S-S, intramolecular H-transfer, cyclization and isomerization mechanisms.

Composition, structural, and thermal analysis of cellulose, hemicellulose, and lignin of reconstituted cut stems in tobacco

In order to encourage effective recycling of tobacco resources in the industry and successfully enhance the quality of reconstituted cut stems (GS30). This study investigates the thermal, structural, and material composition of GS30. It was found that compared with high-quality tobacco leaves and cut stems, the contents of important macromolecules including cellulose, hemicellulose and lignin in GS30 were 21.74 ± 1.14 %, 3.66 ± 0.56 %, and 1.69 ± 0.46 % respectively. Its content is smaller than that of blank cut stems but similar to high-quality tobacco leaves. The important macromolecular structures were further analyzed for their surface morphology and crystal structure using FTIR, XRD, SAXS, and SEM. After analyzing the thermal cracking behavior of GS30 through PY-GC-MS, it was found that GS30 has four weight loss stages and thermal cracking releases near 30 types of aroma substances, showing obvious advantages in releasing aromatic gases. This demonstrates that the structure of GS30 obtained from secondary processing of discarded tobacco leaves is loose and easy to burn and decompose, which can effectively reduce the release of cigarette tar.

Characteristics and kinetics of in-situ catalytic cracking of biomass tar in a micro dual bed reactor

This research introduces a novel micro dual bed reactor, combining rapid pyrolysis in a top-down with a fluidized bed for biomass tar catalytic cracking assessment. The study initially examines the impact of reactor zones on biomass pyrolysis, followed by an exploration of thermal and catalytic cracking behaviors of in-situ biomass tars using three fluidizing media. It delves into the generation of cracking gas and tar cracking reaction kinetics, based on the evolutionary trends of the gas. The process involves two distinct stages (S1 and S2). In S1, olivine shows the highest tar conversion rates at 650 °C and 750 °C, while char peaks at 850 °C. In S2, char leads in conversion rate and reaction time, with a preference for CO and H2. Tar conversion rates at high temperatures follow the order char > olivine > sand, and reaction times vary as olivine > sand > char. Temperature affects tar cracking rates due to thermal and catalytic effects interplay. This study applies an integral method to solve the kinetics under varying conditions, providing insights into tar behaviors during both thermal and catalytic cracking. These findings support designing and optimizing tar removal units in biomass gasification, potentially reducing tar production and enhancing gas quality.

Multiphysics phase-field modeling for thermal cracking and permeability evolution in oil shale matrix during in-situ conversion process

In-situ conversion process (ICP) is a promising recovery technology for economically effective exploitation of unmatured oil shale. High temperature treatment during ICP facilitates the chemical conversion of kerogen content in oil shale, while markedly improving the accessibility of pyrolyzed fluid through thermally-induced microcracks. Although extensively studied experimentally, the microstructure development in shale is not fully understood due to the lack of consideration for multiphysics effects during ICP at the mineral scale. This paper presents a numerical study on thermal cracking and permeability evolution in oil shale matrix during in-situ conversion process. To this end, a multiphysics phase-field model for investigating thermo-mechanical response, chemical reaction, and seepage behavior is developed, while arbitrary crack growth in heterogeneous shale matrix is naturally predicted using the phase-field method for fracture. Implementing the proposed numerical model, thermal cracking of heterogeneous granodiorite is first simulated, from which the numerical outcome regarding crack morphology is reasonably consistent with experimental data. Permeability evolution of oil shale matrix is found to be attributed to early-stage thermal crack propagation and late-stage kerogen decomposition by correlating multiple variables. Anisotropic permeability is also observed and investigated by examining crack morphology, pore-space interconnectivity and fluid permeation. Further analysis reveals that the shale matrix microstructure, in-situ stress and heating temperatures play vital roles in influencing thermal cracking and permeation behaviors of the shale matrix. The results provide a unique perspective to understanding thermal cracking and permeability augmentation of heterogeneous rocks.

A novel bi-modular elastic algorithm in particle Flow Code for thermal cracking modeling of rock

Experimental studies indicated that most rocks exhibit distinct elastic moduli under compressive and tensile loading, leading to intricate stress conditions in rock mass under thermal–mechanical coupling. It is an urgent demand for advanced numerical methods that can simultaneously consider the bi-modular elasticity of rock, thermal–mechanical coupling effects, and thermal cracking behaviors to improve understanding of geological science. The Balanced Interface Method (BIM), a novel bi-modular elastic algorithm is proposed in Particle Flow Code to investigate the thermal–mechanical behavior of bi-modular elastic materials. Firstly, this study introduces the calculation principle of BIM and presents the calibration procedure for bi-modular elastic materials, which is further validated through two case exercises. Subsequently, the thermal–mechanical coupling algorithm is improved by utilizing the Flat-Joint Model (FJM), and a correction method for the position of the compression-tension interface based on BIM for the thermal–mechanical coupling process is introduced, which is then verified by a comprehensive transient heat conduction case with different elastic assumptions. Lastly, a cracking example induced by thermal–mechanical coupling is simulated. The numerical results demonstrate consistency with previous studies and reveal a significant improvement in the thermal cracking behavior of rock, proving the developed algorithm’s necessity in investigating the coupled thermal–mechanical problem.

Evaluation index for the low-temperature performance of asphalt mixture based on relaxation characteristics of thermal cracking mechanism

ABSTRACT The thermal cracking behaviour of asphalt pavement is complex and includes thermal contraction, low-temperature relaxation, and low-temperature damage. However, using relaxation characteristics alone instead of low-temperature properties leads to an incomplete evaluation. In this paper, the relationship between viscoelastic properties and relaxation characteristics was analyzed. Based on the time domain characteristics of relaxation, the relaxation rate and cumulative stress at per unit strain rate (CSSR) were proposed as evaluation indexes corresponding to the long-term/short-term characteristics of the relaxation. By combining the relationship among the low-temperature performance obtained by Thermal Stress Restrained Specimens Test (TSRST) and relaxation characteristics, evaluation indexes for the low-temperature performance of asphalt mixture were preferably selected. The results show that asphalt binders dominate the relaxation characteristics of asphalt mixtures, but do not directly replace the low- temperature performance of asphalt mixtures. The relaxation characteristics expressed by the traditional viscoelastic indexes were insufficient to fully evaluate the low- temperature performance of asphalt mixtures. Furthermore, the results of the relaxation characteristic index for evaluating the low-temperature performance were different under different temperature conditions, indicating that performance at a single temperature cannot replace the low-temperature performance at all temperatures.

Effect of Long-Term Aging on Fatigue and Thermal Cracking Performance of Polyphosphoric Acid and Styrene-Butadiene-Styrene-Modified Bio-Blend Bitumen.

Polyphosphoric acid (PPA) and styrene-butadiene-styrene (SBS) were adopted to produce PPA-SBS-modified bio-blend bitumen, which achieved excellent mechanical performance. However, its long-range performance, such as the fatigue and thermal cracking behavior under long-term thermal oxidation, is not well understood. Therefore, a pressure aging vessel (PAV) system was applied to simulate the aging behavior of the bitumen under the action of thermal oxidation. Then, a linear amplitude sweep (LAS) test combined with a viscoelastic continuum damage (VECD) model was applied to investigate the fatigue properties of the bitumen. Moreover, a bending beam rheometer (BBR) test was conducted to evaluate the thermal cracking resistance of the bitumen before and after PAV aging. Meanwhile, an atomic force microscope (AFM) was applied to observe the microscopic topography. The results show that the original compound-modified bitumen can bear more fatigue damage than that of the control bitumen at the failure point, and it also has excellent fatigue resistance at 2.5%, 5%, 7.5%, and 10% applied strain. Moreover, the VECD model can accurately predict the fatigue life of the bitumen under different applied strains. The variation ratio of stiffness modulus for the compound-modified bitumen is below that of the control bitumen after PAV aging, so it shows a better anti-aging performance. Finally, the AFM test shows that PPA and bio-bitumen decrease the heterogeneity of the bitumen, reducing the difference between phases.

Thermal-mechanical coupled XFEM simulation of low temperature cracking behavior in asphalt concrete waterproofing layer

Asphalt concrete waterproofing layer (ACWL), which is used to reduce the moisture impact on high-speed railway structure, tends to crack at low temperatures and thus reduces its durability. Therefore, understanding the low-temperature cracking behavior of ACWL from both the material and structure perspectives is of great significance. In this study, thermal-mechanical coupled simulation based on extended finite element method (XFEM) was employed for research on this aspect, with the experimental and numerical monotonic-loading overlay test (ML-OT) to determine the fracture parameters of railway asphalt concrete materials and full-scale model to characterize the thermal cracking behaviors of ACWL. The results firstly showed that both the ML-OT and thermo-mechanical simulation on ACWL structure presented a four-stage fracture process, i.e. elastic response, crack initiation, crack propagation and final failure stage, at the temperature of −20 °C. Secondly, the effects of material formulation and structure design on the low-temperature cracking resistance was investigated: 1) In terms of material formulation, the binder B and gradation AC-13 was superior to their counterparts; 2) In terms of structure design, the ACWL layer thickness of 8 cm was the most unfavorable in the range of 6–16 cm, and the increased temperature difference accelerated the thermal cracking propagation in ACWL at the average temperature of −20 °C. In addition, two thermal stress mitigation strategies, namely laying the geotextile at base joints and setting expansion joints, were found to effectively prevent and delay the emergence of thermal cracks in ACWL at low temperatures. For recommendation, the developed thermal-mechanical coupled simulation framework, the custom-designed railway asphalt concretes, and the recommended ACWL thickness of 12 cm were applicable in future studies and engineering projects.

Exploring the effect of low-heat cement on early-age thermal cracking resistance of roller-compacted concrete

In this paper, the early-age thermal cracking behavior of roller-compacted concrete prepared with low-heat cement (LHC) was investigated using a concrete temperature stress testing machine. The test results show that under the same restraint degrees, the concrete cracking temperature difference increased at a diminishing rate with the increasing concrete curing age; when loaded at the same curing age, the cracking temperature difference of the concrete increased with the decreasing concrete restraint degree. Under a fully restraint condition (100% restraint degree), the LHC roller-compacted concrete was able to resist cracking under sudden decreases in temperature in the range of 2.96–4.68 °C at curing ages of 3–14 d. A numerical simulation and theoretical derivation were used to verify and extend the analysis of the cracking temperature difference of the LHC roller-compacted concrete under different restraint conditions.

Early age thermal cracking resistance of basalt fiber-reinforced concrete for mass concrete structures under restraint condition

This study investigated the early-age thermal cracking behavior of basalt fiber (BF)-reinforced concrete exposed to rapid temperature changes (0.5 °C/h) at different curing ages of 3, 7, and 14 d, at fiber volume dosages of 0 %, 0.1 %, and 0.5 % using a developed temperature stress testing machine (TSTM). The material properties testing results demonstrated that as the BF dosage increased from 0 % to 0.1 %, and 0.5 %, the greatest reductions in the elastic modulus of BF-reinforced concrete relative to ordinary concrete were 18.9 % and 8.3 %, respectively, and the greatest increases in the axial tensile strength were 5.6 % and 13.5 %, respectively. The thermal stress test results indicated that the thermal cracking risk (cracking temperature difference) of BF-reinforced concrete vary nonlinearly with the increasing basalt fiber dosage. As the BF dosage increased from 0 % to 0.1 % and 0.5 %, the maximum increases in the temperature drop were 42.9 % and 18.3 %, respectively. Additionally, the stress relaxation of concrete subjected to a rapid temperature change appeared gradually after 9 h loading, and the concrete with a fiber dosage of 0.1 % showed the greatest degree of relaxation (i.e., 0.216), which was greater than that of reference concrete by 42.1 %. In regard to the thermal cracking resistance, the optimal BF dosage obtained in the current research was 0.1 % (vol.). The relationship established between the cracking temperature differences and BF dosages can help engineers to effectively assess the risk of surface temperature cracking in harsh environments during the construction period of mass concrete structure.

A Digital Rock Physics-Based Multiscale Multicomponent Model Construction of Hot-Dry Rocks and Microscopic Analysis of Acoustic Properties under High-Temperature Conditions

Summary The development of hot-dry rock (HDR) resources relies on the accurate evaluation of acoustic properties. The acoustic properties are usually measured by rock physical experiments. However, the high-temperature heating experiment is difficult because of high costs, long time-consumption, and complex operations. Hence, digital rock physics (DRP), a less time-consuming and more economical way, is used to analyze the acoustic properties. Here, multiple scanning experiments, including X-ray computed tomography (X-ray CT) for reconstructing 3D model, quantitative evaluation of materials by scanning electron microscopy (QEMSCAN), and modular automated processing system (MAPS), are conducted, and a fusion method of multiple scanning images is proposed to solve the contradiction between image resolution and the sample size caused by small pore size and complex mineral distribution and to generate the multiscale multicomponent digital rock. Then, the acoustic numerical modeling at high temperatures is conducted, where the essential idea is to derive the theoretical correlation between the elastic moduli of the minerals and the temperatures to obtain the elastic moduli of minerals at different temperatures. Finally, the acoustic properties of the digital rock are calculated, and the microscopic mechanism at high temperatures is studied in detail. The simulating results demonstrate that bulk modulus, shear modulus, Poisson’s ratio, Young’s modulus, P-wave velocity, and S-wave velocity decrease as the temperature rises. More importantly, the thermal cracking behavior of HDR is represented, and fractal Brown motion is utilized to generate the fractured digital rock. The simulation results of fractured digital rock illustrate that it is the fracture to cause rapid decline of acoustic properties after 250℃. Overall, this pore-scale work accurately illustrates the acoustic properties of HDR and provides a new idea to study the rock physics properties at high temperatures and a microscopic interpretation for geothermal fracturing development.

A coupled thermo-mechanical bond-based smoothed particle dynamics model for simulating thermal cracking in rocks

A smoothed particle dynamics (SPD) method was proposed for crack propagation analysis. The computational efficiency of this method was significantly better than the traditional smoothed particle hydrodynamics (SPH) method. In the SPD method, the motion equations were approximated by a Lagrange kernel determined by the coordinates of the material in the initial configuration. A coupled thermo-mechanical bond-based smoothed particle dynamics (TM-BB-SPD) model was proposed for simulating the thermal cracking process of rocks. In the SPD program, the thermal cracking behaviors of rock, such as crack initiation and propagation, were dynamically tracked by capturing the damage state of virtual bonds. The robustness and accuracy of the proposed SPD method and TM-BB-SPD model were verified using two benchmark examples. The numerical results were in good agreement with the experimental results and analytical solutions. In addition, the effects of the thermal expansion coefficient and homogeneity index on the mode of thermal cracking in the rock disc were also investigated. The numerical results were also in good agreement with previous experimental observations. Moreover, the numerical results showed that with an increase in the homogeneity index, the mode of crack propagation in rock gradually changed from non-smooth to smooth types of fracture.

Investigation on the thermal cracking of shale under different cooling modes

Thermal stimulation method can be effectively utilized to enhance the flow performance in tight porous media with an induced thermal shock (TS) using the injection of cryogenic fluids. In order to reveal the thermal cracking behavior and the mechanism of shale under different cooling modes, thermal cooling laboratory experiments of shale samples were carried out in the current paper. Combined the numerical simulations and laboratory experiments, the thermal cracking behavior of shale under different cooling modes was studied. The laboratory experiments results show that the macroscopic thermal cracking tended to occur under thermal shock at a temperature of more than 400 °C. A heat transfer numerical simulation method under different cooling modes was established to analyze the temperature field distribution and the variation in the temperature gradient of shale from the perspective of heat transfer. For different cooling modes, the evolutionary trend of temperature gradient, thermal shock factor and dynamic thermal stress formed within the shale sample was consistent. The maximum values always occurred near the surface of the sample. Thermal shock factor, which can describe the ability of heat to cause damage to rocks, was introduced. The thermal shock factor could realize the quantitative classification of thermal cooling capacity. According to the evolutionary pattern of thermal shock factor, the specific time of the most serious internal fracture of shale samples could be determined. Dynamic thermal stress generated inside the shale under different cooling modes was also calculated to analyze the cause of shale cracking. The difference in the convective heat transfer coefficient of various cooling media was closely related to the fracture propagation. Thermal stimulation will be an efficient and a promising means to generate more complex fracture networks for the development of unconventional tight shale reservoirs using the combination of formation heat treatment (FHT) and thermal shock (TS).

Evaluation of early-age thermal cracking resistance of high w/b, high volume fly ash (HVFA) concrete using temperature stress testing machine

Fly ash (FA) is an environmentally hazardous industrial solid waste. High FA replacement levels on properties of concrete with low w/b have been widely investigated, however, studies on the thermal cracking behavior of HVFA concrete with high w/b are lacking. This paper investigated the effect of high volume fly ash (HVFA) on mechanical properties and thermal cracking resistance of concrete with a high w/b of 0.45 using temperature stress testing machine (TSTM). An adiabatic curing condition during the temperature rise stage and a rapid cooling during the temperature drop stage were applied on test specimens. The effectiveness of concrete with different FA replacement levels (0%, 20%, 50% and 80%) on the thermal cracking potential of concrete under a restraint degree of 100% has been addressed. Results showed that the mechanical properties of concrete mixture decreased with the increasing FA replacement level; the ratio of creep-to-free strain (i.e., relaxation behavior) of concrete mixture decreased when the FA replacement level reached 20%, and converted to increase for the FA replacement level ranging from 50% to 80%; FA replacement level with 50% showed a desirable effect on the thermal cracking resistance enhancement of high w/b concrete mixture regarding restrained cracking control.

Sulfur types distribution and the fast thermal-cracking behaviors of sulfur-containing compounds in Buton oil sand bitumen

The distribution of various types of sulfur in Buton oil sand bitumen (OSB) were investigated at the level of group-fractions corresponding to saturates, aromatics, resins and asphaltens (SARA). The separation of different types of sulfur-containing compounds (SCCs) in saturates and aromatics with weak polarity was performed using selective oxidization coupled with alumina column chromatography. However, various types of SCCs were isolated from resins via selective oxidization combined with solvent fractional extraction. It was found that sulfide sulfur, thiophenic sulfur and sulfoxide/sulfone sulfur accounted for 39.31%, 53.93% and 6.74% in total sulfur of OSB, respectively. Sulfidic sulfur and thiophenic sulfur in OSB had the highest enrichment in aromatics, followed by that in asphaltenes and resins. In order to further link the theoretical study with the actual process of thermal cracking process, the fast thermal cracking of OSB to produce oil sand oil under different temperature and over silica sand, calcium aluminate and FCC catalyst was conducted by a laboratory-scale fluidized bed reactor. The composition and classes of SCCs existed in oil sand oil were evaluated via GC–MS, which were indispensable to gain an in-depth insight into thermal cracking behavior of SCCs in OSB. Results indicated that SCCs in oil sand oil obtained under different temperature and over different heat carriers had the distinct composition, and yet were all classified into up to 11 classes. The detected SCCs in oil sand oil obtained over silica sand at different temperatures all contained AT&AM, thiophenes, BTs, HydroDBTs, DBTs, HydroNTs, and NTs. The composition and classes of SCCs in oil sand oil, nonetheless, were inclined to be enriched as the temperature enhanced. Furthermore, the detected SCCs in oil sand oil obtained over calcium aluminate featured the most abundant class distribution, followed by that over silica sand and FCC catalyst. The relative content of AT&AM, thiophenes and BTs, the relative content of NTs and four species of Hydrothiophenes, and the relative content of DBTs, PTs and BNTs accounting for SCCs in oil sand oil was largest when the heat carriers were silica sand, calcium aluminate and FCC catalyst, respectively.

A phase-field thermomechanical framework for modeling failure and crack evolution in glass panes under fire

This paper presents a novel phase-field thermomechanical modeling framework for predicting complicated behaviors of thermal cracking in glass panes under fire. The main idea is to incorporate the proposed mathematical model, which calculates the exact deformation of the mesh elements, into the variational phase-field model to simulate the thermal fracture behavior in glass panes in an effective manner. The developed model improves upon previous attempts to predict thermal cracking in the following ways: (1) in a major departure from the classical phase-field simulation of thermomechanical fracture, crack evolution can be predicted using only temperature distributions; the phase-field formulations are kept fixed to overcome mesh dependency and convergency; (2) the new modeling framework directly transforms temperature variations into thermal strains (rate of loading) using fewer mesh elements and a larger time step, thus substantially reducing the computational effort; and (3) the proposed model can simultaneously predict multiple cracks distributed in any arbitrary space in the glass panes more realistically than the previous numerical models, regardless of glass pane type and size, fixation method, and thermal loading variation. The proposed coupling model is validated through comparisons against experimental observations and ANSYS simulations. Moreover, the validated model is used to examine for the first time the effect of real engineering influential conditions, namely the heating rate, glass pane size ratio under non-uniform thermal loading, and glass pane fixation with a frame on three sides, on thermal cracking behavior.

A thermal cracking pattern-based multiscale homogenization method for effective thermal conductivity of steel fiber reinforced concrete after high temperature

The mesoscopic thermal cracking behavior in steel fiber reinforced concrete (SFRC) caused by high-temperature load can result in a substantial reduction of effective thermal conductivity (ETC) at macroscale level. In this study, a multiscale homogenization method for identifying the ETC of thermally damaged SFRC is proposed. This new method is characterized by the consideration of crack thermal resistance effect rather than using temperature-dependent thermal conductivities of components in cementitious composite. A series of experiments on thermal conductivity of mortar, plain concrete, and SFRC heated at various temperatures is performed. The method predictions satisfy the experimental results extremely well when the interfacial thermal resistance (ITR) coefficient is assumed to increase linearly with temperature. The numerical and experimental results show that the ITR effect makes approximately 50%, 36%, and 7%–12% contributions to the overall thermal conductivity reductions in the mortar, plain concrete, and SFRC heated up to 600 ∘C, respectively. Moreover, it is found that the trend and magnitude of ETC reduction caused by heating increase with the increase in particle content and particle-matrix thermal conductivity ratio due to the synergistic effect of heat bridge and ITR.

Soy-based rejuvenated asphalt binders: Impact on rheological properties and chemical aging indices

The main purpose of this study is to evaluate the performance of four recycling agents – one conventional petroleum-based (PB) oil and three soy-based (SB) bio-oils – in terms of rutting, fatigue and thermal cracking behavior and chemical properties of the rejuvenated asphalt binders. The PG grade was used to assess the high and low critical temperatures, and the MSCR and LAS tests were used to evaluate the rutting and fatigue characteristics, respectively. Changes in the chemical aging groups were tracked by means of FTIR spectroscopy. The bio-oils have great potential to be employed as recycling agents as they restored the high and low critical temperatures of the aged binders. The bio-rejuvenated binders presented an excessive mass loss compared to the standard rejuvenated one despite their enhancement in the fatigue life. The carbonyl indices were reduced, showing that the rejuvenators were capable of mitigating the effect of binder aging.

Sensitive Group-Fractions Affecting the Formation of Thermal-Cracking Volatile Products for Buton Oil Sand Bitumen: Thermal-Cracking Behaviors, Volatile Products, and Determination

Sensitive Group-Fractions Affecting the Formation of Thermal-Cracking Volatile Products for Buton Oil Sand Bitumen: Thermal-Cracking Behaviors, Volatile Products, and Determination

Influence of repeated heating on physical-mechanical properties and damage evolution of granite

Granite is commonly seen in tunnels, historical buildings, or energy generation/storage facilities, where repeated heating-cooling cycles can occur during regular operation or fire accidents. In this study, physical and mechanical properties as well as the cracking behaviour of Eibenstock granite during single and repeated heating-cooling cycles are described. Generally, repeated thermal cycling has only a small influence on properties and the cracking behaviour of granite. Thin section observations show that the main minerals of granite do not show big changes up to 1000 °C. P-wave velocity and open porosity measurements reveal that thermal induced microcracks mainly develop before quartz transition temperature (573 °C), and after this temperature these earlier-formed microcracks will be widened rather than newly formed. A hardening behaviour of granite after heat treatments can be observed in the temperature range of 25 °C–400 °C due to the evaporation of water. At higher temperatures, further developed or extended microcracks will lead to a reduction of both, uniaxial compression strength (UCS) and stiffness. Back-calculated parameters show that the thermal induced cracking might reduce the interlocking between the crystals by weakening or removing the cohesion rather than the friction angle. Tensile strength shows a continuous decrease with the development of thermal induced cracks, and no obvious difference can be observed between single and repeated heating-cooling scenarios. Additional testing on samples with different dwelling time shows that thermal time has a minor influence on the thermal cracking behaviour of granite. The slight difference at 1000 °C in terms of P-wave velocity and open porosity between single and repeated thermal cycles is mainly caused by repeated shrinkage and widening of cracks or closing and reopening of some microcracks. All in all, repeated thermal cycling has a negligible influence on physical and mechanical properties. The same holds for the cracking behaviour of granite.