Journal articles: 'Spallings'

1

Lee, Chang Soon, In Shik Cho, Young Shik Pyoun, and In Gyu Park. "Study of Inner Micro Cracks on Rolling Contact Fatigue of Bearing Steels Using Ultrasonic Nano-Crystalline Surface Modification." Key Engineering Materials 462-463 (January 2011): 979–84. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.979.

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The purpose of this study is to analyze the effect of ultrasonic nano-crystalline surface modification (UNSM) treatment on rolling contact fatigue (RCF) characteristics of bearing steels. It was found that severe plastic deformation occurred at surface by over 100 µm after UNSM treatment. The micro surface hardness was increased by 18%, and the measured compressive residual stress was as high as -700~-900MPa. The polymet RCF-2 roller type RCF test showed over 2 times longer fatigue lifetime after UNSM treatment under Hertzian contact stress of 425.2kg/mm2 and 8,000 rpm. And SEM study showed a spalling phenomenon at the samples which went through the RCF test after UNSM treatment. Samples before UNSM treatment produced surface initiated spalls and multi shear lips by progressive spalling at the end along the rolling direction, but sub-surface initiated spalls were formed without multi shear lips after UNSM treatment. The spalling occurred at once, and the size and depth of spalls were larger than those before UNSM treatment. And micro cracks were found to form within the spallings after UNSM treatment, and stress distribution at the maximum Herzian shear stress through these micro cracks is thought to improve the fatigue lifetime of bearing materials.

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2

Ai, Alan Xiaolan, and Herbert S. Cheng. "Numerical Simulation of Elastohydrodynamically Lubricated Contacts With Rough Surfaces." Applied Mechanics Reviews 47, no. 6S (June 1, 1994): S221—S227. http://dx.doi.org/10.1115/1.3124411.

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Transient numerical analysis to elastohydrodynamically lubricated point contacts with rough surfaces is described. The numerical simulation is based on the multigrid method. Three types of surface roughness: single dent or bump, oblique waviness and random roughness are reviewed. Under heavily loaded conditions, results reveal a strong domination of Couette flow (convective flow). The presence of sliding greatly increases pressure fluctuation and as a consequence may lead to surface-initiated spallings. For obliquely orientated roughness, lubricant flow intends to deform the ridges and create primarily longitudinal passages.

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Hu, Pan, Haitao Wang, Guiyun Tian, Zeyu Dong, Fasheng Qiu, and Billie F. Spencer. "Wireless Localization of Spallings in Switch-Rails With Guided Waves Based on a Time–Frequency Method." IEEE Sensors Journal 19, no. 23 (December 1, 2019): 11050–62. http://dx.doi.org/10.1109/jsen.2019.2934159.

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Franke, L., and R. Reimann-Oenel. "Beobachtungen zum Stofftransport und zu einhergehenden Schädigungseffekten in porösen Baustoffen / Observations of mass transport and related deterioration mechanisms in porous building materials." Restoration of Buildings and Monuments 6, no. 4 (August 1, 2000): 451–62. http://dx.doi.org/10.1515/rbm-2000-5492.

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Abstract It is reported about substance migration problems and their consequences, which have been investigated experimentally and which could be particularly relevant with regard to repair and restoration of historic buildings. One aim of the investigations was to find out, whether facades, treated with water repellent agents, showing non treated areas, can be affected in their long time behaviour. Such lacks can be due to non careful application of the repellent agent. In addition, investigations were made to find out. of coatings on salt containing mineral substrates, especially natural stones can reduce their life time. As a result of the experiments and the theoretical considerations, it follows, that a lack in water repellent treatment. could cause the risk of crust-development spallings in environment of non treated spots in the case that substrate is salt contaminated and moisture exchange takes place. All experiments with coatings, performed under the same conditions, show, that the coated surfaces have a more favourable behaviour than the same surfaces without coatings.

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5

Knowles, M. K., F. D. Hansen, T. W. Thompson, J. F. Schatz, and M. Gross. "Review and perspectives on spallings release models in the 1996 performance assessment for the Waste Isolation Pilot Plant." Reliability Engineering & System Safety 69, no. 1-3 (September 2000): 331–41. http://dx.doi.org/10.1016/s0951-8320(00)00037-5.

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6

Berglund, J. W., J. W. Garner, J. C. Helton, J. D. Johnson, and L. N. Smith. "Direct releases to the surface and associated complementary cumulative distribution functions in the 1996 performance assessment for the Waste Isolation Pilot Plant: cuttings, cavings and spallings." Reliability Engineering & System Safety 69, no. 1-3 (September 2000): 305–30. http://dx.doi.org/10.1016/s0951-8320(00)00036-3.

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7

Guo, Y. S. H., Wei Shen Zhu, Shu Cai Li, R. H. C. Wong, and B. Sin. "Growth Pattern Study of Closed Surface Flaw under Compression." Key Engineering Materials 353-358 (September 2007): 158–61. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.158.

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Under extra compressive stress, some phenomena of rock spallings and fractures often exist on rock mass located in sidewalls of underground house and tunnels. It is the reason that the crack growth and coalescence initiation from original flaws (or faults) in rock mass. In the previous studies, many researchers took a flaw as a through flaw (2-dimentional model), but the flaws are not always through the whole rock mass in fact, most of them are only near the surface of rock mass, These are so named as surface flaws. They belong to three dimensional (2-D) flaws. Now, the reports on initiation and growth of 3-D surface flaw are few. So, for the investigation on growth patterns of 3-D surface flaw, a series of samples containing a surface flaw were carried out using frozen casting resin material at about -30°C temperatures. The surface flaw was made of a polyester film was used to model a single closed flaw on rock mass. The experimental results show that the wrapping wing crack (Mode I) initiated at the ends (or tips) of surface flaw first, and then formed a kinking zone (mixed crack zone) at a certain place at the middle of surface flaw region. Some petal cracks (Mode III) and shell-shaped cracks (Mode III) would grow at the middle place of flaw. A big fin crack (Mixed Mode) also emerged in middle of flaw and grown along loading direction. Finally, a team of large cracking curved faces deformed inside the resin specimen; the whole specimen would be splitted off by the initiation and growth of the cracks. The reasons lead to the fracture patterns of 3-D closed surface flaw were provided with brittle fracture mechanics theory in the article, preliminarily.

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8

PRESTON, F. W. "THEORY OF SPALLING*." Journal of the American Ceramic Society 16, no. 1-12 (October 17, 2006): 131. http://dx.doi.org/10.1111/j.1151-2916.1933.tb19208.x.

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9

Buravova, Svetlana. "Erosion spalling mechanism." Wear 157, no. 2 (September 1992): 359–70. http://dx.doi.org/10.1016/0043-1648(92)90072-g.

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10

Zhao, Jie, Jian Jun Zheng, and Gai Fei Peng. "Modeling of Vapor Pressure Build-Up in Heated High-Performance Concrete." Applied Mechanics and Materials 204-208 (October 2012): 3691–94. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.3691.

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Under high temperature conditions, such as fire, high-performance concrete will undergo material degradation or even spalling. Spalling is the most detrimental to concrete structures. To prevent concrete from spalling, the mechanism should be understood. Since the build-up vapor pressure in concrete is supposed to play a dominant role in spalling, a vapor pressure prediction model is proposed in this paper to quantitatively analyze the vapor pressure, which can be used for the spalling mechanism study.

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11

Tian, Kai Pei, Yang Ju, Hong Bin Liu, Jin Hui Liu, Li Wang, Peng Liu, and Xi Zhao. "Effects of Silica Fume Addition on the Spalling Phenomena of Reactive Powder Concrete." Applied Mechanics and Materials 174-177 (May 2012): 1090–95. http://dx.doi.org/10.4028/www.scientific.net/amm.174-177.1090.

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The explosive spalling of high-strength concrete due to fire is a problem that has garnered increasingly widespread attention, particularly the explosive spalling of reactive powder concrete (RPC). For years, based on the vapor pressure mechanism, the addition of fibers has been demonstrated to be somewhat effective in protecting against spalling. However, relevant experiments indicate that fibers are not effective for dense concrete, which is a challenge for the simple vapor pressure mechanism in providing spalling resistance for RPC. The authors found that silica fume plays an important role in the explosive spalling of RPC. Thus, four classes of RPCs with different ratios of silica fume were prepared, and the spalling phenomena and the inner temperature distribution during heating were investigated. The results show that silica fume content has a prominent effect on the spalling process of RPC.

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12

Zhao, Jie, Jian Jun Zheng, and Gai Fei Peng. "Fire Spalling Modeling of High Performance Concrete." Applied Mechanics and Materials 52-54 (March 2011): 378–83. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.378.

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Under high temperature conditions, such as fire, high performance concrete will undergo material degradation or even spalling. Spalling is the most detrimental damage to concrete structures. To prevent concrete from spalling, the mechanism should be understood. In this paper, an anisotropic damage model, in which both the thermal stress and vapor pressure are incorporated, is presented to analyze the spalling mechanism. The spalling phenomenon is studied based on two cases of different moisture contents. It is concluded that when the vapor pressure is present, concrete will behave much more brittlely.

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13

Wang, Kaiyun, Wanming Zhai, Kaikai Lv, and Zaigang Chen. "Numerical Investigation on Wheel-Rail Dynamic Vibration Excited by Rail Spalling in High-Speed Railway." Shock and Vibration 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/9108780.

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Spalling in contact surface of rail is a typical form of rolling contact fatigue, which is a difficult problem to solve in railway. Once the spalling occurs in the rail, the wheel-rail dynamic interaction will become more severe. The wheel-rail dynamic interaction is investigated based on the theory of vehicle-track coupled dynamics in this paper, where the excitation modes of the rail spalling failure are taken into consideration for high-speed wheel-rail system. A modified excitation model of rail spalling failure is proposed. It can enable the investigations on two kinds of excitation modes in wheel-rail system due to the rail spalling, including the pulse and the harmonic excitation modes. The excitation mode can be determined by the ratio of the spalling length to its critical length. Thus, the characteristics of wheel-rail dynamic vibration excited by two kinds of excitation are simulated in detail. Consequently, the limited value of the spalling length is suggested for high-speed railway.

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14

Lakhani, Hitesh, and Jan Hofmann. "Effect of spalling on predicted temperature gradients and flexural capacity: numerical model." Journal of Structural Fire Engineering 11, no. 2 (November 17, 2019): 151–65. http://dx.doi.org/10.1108/jsfe-01-2019-0010.

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Purpose The paper aims to present an advanced 2 D transient heat transfer analysis capable of accounting for the effect of spalling in terms of amount, location and time. The model accounts for moving thermal boundary conditions to comply with the changing member cross section. The discussed numerical model provides a tool to quantify the effect of spalling on the flexural capacity of reinforced concrete beams. Design/methodology/approach The implementation of the presented numerical model in an in-house code and its validation has been discussed. The thermal subroutine has been sequentially coupled with the mechanical subroutine (sectional-analysis) to compute the variation of sectional moment carrying capacity with exposure time. Findings The temperatures predicted while considering spalling were in good agreement with experiments available in literature. The presented results also emphasise the importance of considering the time of spalling. The results also show that the fire rating of simply supported beams is also affected by spalling in the compression zone. Research limitations/implications It should be acknowledged that the model does not predict spalling, rather is developed as a tool to study the effect of spalling. The model takes the information related to spalling in terms of the location, amount and time, as user input. Originality/value The paper quantitatively presents the effect of spalling on the predicted temperature variation across the beam cross section and the moment carrying capacity.

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15

Zhou, Mingliang, Wen Cheng, Hongwei Huang, and Jiayao Chen. "A Novel Approach to Automated 3D Spalling Defects Inspection in Railway Tunnel Linings Using Laser Intensity and Depth Information." Sensors 21, no. 17 (August 25, 2021): 5725. http://dx.doi.org/10.3390/s21175725.

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The detection of concrete spalling is critical for tunnel inspectors to assess structural risks and guarantee the daily operation of the railway tunnel. However, traditional spalling detection methods mostly rely on visual inspection or camera images taken manually, which are inefficient and unreliable. In this study, an integrated approach based on laser intensity and depth features is proposed for the automated detection and quantification of concrete spalling. The Railway Tunnel Spalling Defects (RTSD) database, containing intensity images and depth images of the tunnel linings, is established via mobile laser scanning (MLS), and the Spalling Intensity Depurator Network (SIDNet) model is proposed for automatic extraction of the concrete spalling features. The proposed model is trained, validated and tested on the established RSTD dataset with impressive results. Comparison with several other spalling detection models shows that the proposed model performs better in terms of various indicators such as MPA (0.985) and MIoU (0.925). The extra depth information obtained from MLS allows for the accurate evaluation of the volume of detected spalling defects, which is beyond the reach of traditional methods. In addition, a triangulation mesh method is implemented to reconstruct the 3D tunnel lining model and visualize the 3D inspection results. As a result, a 3D inspection report can be outputted automatically containing quantified spalling defect information along with relevant spatial coordinates. The proposed approach has been conducted on several railway tunnels in Yunnan province, China and the experimental results have proved its validity and feasibility.

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16

Cui, Feng, Tinghui Zhang, and Xiaoqiang Cheng. "Research on Control of Rib Spalling Disaster in the Three-Soft Coal Seam." Shock and Vibration 2021 (June 16, 2021): 1–15. http://dx.doi.org/10.1155/2021/2404218.

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Rib spalling disaster at the coal mining faces severely restricted the safe and efficient output of coal resources. In order to solve this problem, based on the analysis of the current status of rib spalling in the three-soft coal seam 1508 Working Face of Heyang Coal Mine, a mechanical model of sliding-type rib spalling was established and the main influencing factors that affect rib spalling are given. The mechanism of grouting technology to prevent and control rib spalling has been theoretically analyzed. A similarity simulation experiment is used to analyze the change law of roof stress under the condition of three-soft coal seam mining. The optimal grouting pressure is determined by a numerical simulation experiment. And, silicate-modified polymer grouting reinforcement materials (SMPGMs) are used in field experiments. After twice grouting operations in the 1508 Working Face, the coal wall was changed from the original soft and extremely easy rib spalling to a straight coal wall and the amount of rib spalling has been reduced by 57.45% and 48.43, respectively. And, the mining height has increased by 0.16 m and 0.23 m, respectively. The experimental results show that the rib spalling disaster of the three-soft coal seam has been effectively controlled.

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17

Hager, Izabela, and Katarzyna Mróz. "Role of Polypropylene Fibres in Concrete Spalling Risk Mitigation in Fire and Test Methods of Fibres Effectiveness Evaluation." Materials 12, no. 23 (November 23, 2019): 3869. http://dx.doi.org/10.3390/ma12233869.

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The explosive behaviour of concrete in fire is observed in rapidly heated concrete. The main factors controlling the occurrence of spalling are related to the material’s low porosity and high density as well as the limited ability to transport gases and liquids. Thus, for high-strength, ultrahigh-strength, and reactive powder concrete, the risk of spalling is much higher than for normal-strength concrete. The paper presents the discussion on the leading hypothesis concerning the occurrence of concrete spalling. Moreover, the methods for spalling prevention, such as polypropylene fibre application, which has been found to be an effective technological solution for preventing the occurrence of spalling, are presented. Various tests and testing protocols are used to screen concrete mixes propensity toward spalling and to evaluate the polypropylene fibres’ effectiveness in spalling risk mitigation. The most effective testing methods were selected and their advantages were presented in the paper. The review was based mainly on the authors’ experiences regarding high performance concrete, reactive powder concrete testing, and observations on the effect of polypropylene fibres on material behaviour at high temperature.

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18

Li, Rong Tao. "Application of Fuzzy Pattern Recognition in Spalling Risk Evaluation of Concrete Structures at High Temperature." Advanced Materials Research 919-921 (April 2014): 451–54. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.451.

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Spalling phenomenon in concrete exposed to high temperatures, e.g. during a fire, can seriously jeopardize the integrity of a whole structure. Spalling risk analysis and evaluation has become the hot topic of research on fire-resistance behavior of concrete structures at present. Based on fuzzy pattern recognition, a model for evaluating spalling risk of concrete structures at high temperature is established according to the factors influencing explosive spalling. The influential factor set is composed of strength, water/cement ratio, fibres content, curing humidity, load level, and heating rate, whose weights are determined by their relative importance. Good agreements between the results of spalling risk prediction and the fire test show the capability of the proposed model in assessing the spalling risk of concrete structures at high temperature, which will provide important reference for the fire resistance design of concrete structures.

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Peng, Gai Fei, Xu Jie Duan, Xue Chao Yang, and Ting Yu Hao. "Behavior of High Performance Steel-Fiber Concrete Exposed to High Temperature in Terms of Spalling and Permeability." Key Engineering Materials 629-630 (October 2014): 252–58. http://dx.doi.org/10.4028/www.scientific.net/kem.629-630.252.

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An experimental investigation was conducted on behavior of high performance steel-fiber concrete subjected to high temperature, in terms of explosive spalling and permeability. A series of concretes incorporated steel fiber at various dosages were prepared, and further processed to have a series of moisture contents. Explosive spalling tests were conducted on control plain concrete and steel fiber concrete. After explosive spalling tests, each of the specimens that didn’t encounter spalling was sawn into two pieces. Crack observations and permeability tests were conducted on the sawn surfaces. The results prove that steel fiber is efficient to avoid spalling concrete under high temperature. The permeability increases significantly after thermal exposure, while it also exhibits an ascending trend with the increase of moisture content. Therefore it is concluded that steel fiber can play a positive effect on explosive spalling of high performance concrete under high temperature, as well as on permeability after thermal exposure.

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Lu, Fang Xia, and Mario Fontana. "Concrete Permeability and Explosive Spalling in Fire." Key Engineering Materials 711 (September 2016): 541–48. http://dx.doi.org/10.4028/www.scientific.net/kem.711.541.

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Permeability of concrete is a good indicator of the risk of explosive spalling, concrete with low permeability is more prone to explosive spalling. To study explosive spalling of concrete, experimental tests on the concrete permeability have been carried out at ETH. The influences from temperature and moisture content have been investigated. The permeability of concrete is found to increase with the temperature and to decrease with moisture content. Based on the test results, a permeability model has been proposed. The explosive spalling has been predicted and an engineering boundary permeability for the liability to spalling is recommended to be 2 × 10-17 m2 for a concrete slab heated according to ISO fire curve. The boundary permeability is influenced by moisture content, tensile strength and heating rate.

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21

Ding, Y., and J. A. Gear. "Spalling depth prediction model." Wear 267, no. 5-8 (June 2009): 1181–90. http://dx.doi.org/10.1016/j.wear.2008.12.064.

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22

He, Fu Lian, Xiao Ming Wang, De Quan Zhang, and Shang Sen He. "Study on Parameters of Support for Control of Roof Fall and Rib Spalling in Large Fully Mechanized Top Coal Caving End Face." Advanced Materials Research 616-618 (December 2012): 421–25. http://dx.doi.org/10.4028/www.scientific.net/amr.616-618.421.

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Key factors affecting the control of roof fall and rib spalling are identified relying on the statistics for characteristics of roof fall and rib spalling distribution, and the regression analysis of the relationships of roof fall and rib spalling to support parameters by measuring actual ground pressures. The effect of support in controlling roof fall and rib spalling is analyzed by setting up a caving arch mechanical model of cataclastic coal and rock mass on fully mechanized caving face, and the key parameters of support are also determined using numerical simulation.

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23

Ye, Wan Jun, Geng She Yang, Xian Li, and Ning Zhuang. "Treatment Materials for Spalling on Loess Slope." Advanced Materials Research 150-151 (October 2010): 425–28. http://dx.doi.org/10.4028/www.scientific.net/amr.150-151.425.

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Spalling on loess slope threats the safety of highway and destroys its ecological environment. This paper proposes treatment materials for medium thickness spalling on loess slope. This materials treat the spalling in loess slope by the Reinforced function of straw, Bonding effect of silt, retain soil moisture and insulation effect of straw silt nutrition materials of silt mixed with straw, and fixation effect of T-shaped spiral steel anchor net, so that the treated slope can be protected and greened. It can effectively reinforce the loess slope, and prevent it from spalling.

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Miah, Md Jihad, Francesco Lo Monte, Roberto Felicetti, Hélène Carré, Pierre Pimienta, and Christian La Borderie. "Fire Spalling Behaviour of Concrete: Role of Mechanical Loading (Uniaxial and Biaxial) and Cement Type." Key Engineering Materials 711 (September 2016): 549–55. http://dx.doi.org/10.4028/www.scientific.net/kem.711.549.

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Fire poses one of the most severe environmental conditions that can act on concrete structures as an external load and can induce severe damages (cracks, spalling) or even lead to collapse. Fire spalling of concrete is a complex phenomenon, which might occur due to pressure build-up in the pores, thermal and load-induced stresses. In this context, ordinary concrete specimens (B40-II and B40-III: fc28days ≈ 40 MPa) were exposed to standard fire curve (ISO 834-1), while a constant uniaxial or biaxial compressive load was applied. Six different levels of uniaxial compressive stress on cubes and four different levels of biaxial compressive stress on slabs have been investigated. The test results showed that loaded specimens are more susceptible to spalling than unloaded specimens, with increasing amount of spalling for higher values of applied load. It has been found that biaxially loaded specimens are more prone to spalling than uniaxially loaded specimens. B40-II concrete (3% of slag) exhibited higher spalling than the B40-III concrete (43% of slag).

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Li, Guosheng, Zhenhua Li, Feng Du, and Zhengzheng Cao. "Study on the Failure Characteristics of Coal Wall Spalling in Thick Coal Seam with Gangue." Advances in Civil Engineering 2020 (December 14, 2020): 1–10. http://dx.doi.org/10.1155/2020/6668458.

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Coal wall spalling is one of the main factors restricting the safe and efficient mining of thick coal seam, and the gangue has an important impact on the coal wall spalling. To obtain the failure characteristics of coal wall spalling in thick coal seam containing gangue, numerical calculation and theoretical research were used to analyze the morphological differences of coal wall spalling with different gangue positions. Besides, the damage depth, width, and stress environment of coal wall panel caused by the position of gangue were mainly studied, and the failure mechanics model of coal seam containing gangue was established by using the stability theory of pressure bar. The results show that, compared with coal wall spalling in coal seam without gangue, coal seam with the lower and middle gangue has a significant weakening effect on the wall spalling, and coal seam with the upper gangue has little effect on the wall spalling. In the case of coal seam with gangue, the upper gangue has the highest risk area of coal wall spalling with the maximum depth and width of 2.0 m and 2.3 m. For coal seam with the upper gangue, the dangerous areas of coal wall spalling are mainly distributed in the vicinity of the gangue; for coal seam without the gangue, they are mainly distributed in the middle of the coal seam. The gangue cannot change the law of the external stress distribution of the coal seam, but it has an obvious impact on the internal stress distribution of the coal seam. With the different positions of the gangue, the stress distribution in the coal seam has a great difference, and the maximum difference is 1.8 MPa. This shows that the stress environment of the coal seam containing gangue has the following typical characteristics: “the external stress is controlled by the overburden fracture, and the internal stress environment is controlled by the gangue.” Through the mechanical analysis of the coal seam containing gangue, it is further verified that the coal seam containing gangue is more prone to spalling at the position of gangue.

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Yu, Xin Meng, Xiao Xiong Zha, and Zhao Hui Huang. "The Influence of Spalling on the Fire Resistance of RC Structures." Advanced Materials Research 255-260 (May 2011): 519–23. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.519.

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A great many of experiments has shown that reinforced concrete (RC) structures suffered from spalling in fire. However, at present there are still no convincing spalling predicting models available due to the inhomogeneous nature and complicated thermo-hydro-mechanical interactions in concrete at elevated temperatures. In order to evaluate the fire resistance of RC structures which are subjected to concrete spalling, a thermal analysis procedure is developed which considers the effects of spalling on the growth of temperature in RC members. The predicted temperatures are then used to model the structural behaviour. The spalled portion of concrete is modelled as "void", which has no thermal and mechanical properties. A series of parametric studies carried out on RC structural members with different boundary conditions shows that the influence of spalling on fire resistance is very significant apart from the RC slabs subject to higher laterally restraint.

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McKinney, John, and Faris Ali. "Artificial Neural Networks for the Spalling Classification & Failure Prediction Times of High Strength Concrete Columns." Journal of Structural Fire Engineering 5, no. 3 (August 19, 2014): 203–14. http://dx.doi.org/10.1260/2040-2317.5.3.203.

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This paper presents the results from two supervised Artificial Neural Networks (ANN) developed for the spalling classification and failure prediction of high strength concrete columns (HSCC) subjected to fire. The experimental test data used for the ANN are based on the HSCC tests undertaken at the Fire Research Laboratories at the University of Ulster. 80% of the chosen experimental test data was used to train the network with the remaining 20% used for testing. In the spalling classification example the key ANN input parameters were; furnace temperature, restraint, loading level, force, spalling degree, failure time and spalling type. This was also the case for the failure prediction example except for spalling type. The networks were trained using the resilient propagation algorithm. A 6-10-3 and 5-10-1 ANN architecture gave the best results for the classification and failure prediction times respectively. The results demonstrate that HSCC can be assessed using ANN.

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Sohn, Y. C., Jin Yu, S. K. Kang, D. Y. Shih, and T. Y. Lee. "Spalling of intermetallic compounds during the reaction between lead-free solders and electroless Ni-P metallization." Journal of Materials Research 19, no. 8 (August 2004): 2428–36. http://dx.doi.org/10.1557/jmr.2004.0297.

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Intermetallic compound (IMC) spalling from electroless Ni-P film was investigated with lead-free solders in terms of solder-deposition methods (electroplating, solder paste, and thin foil), P content in the Ni-P film (4.6, 9, and 13 wt% P), and solder thickness (120 versus .200 μm). The reaction of Ni-P with Sn3.5Ag paste easily led to IMC spalling after 2-min reflow at 250 °C while IMCs adhered to the Ni-P layer after 10-min reflow with electroplated Sn or Sn3.5Ag. It has been shown that not only the solder composition but also the deposition method is important for IMC spalling from the Ni-P layer. The spalling increased with P content as well as with solder volume. Ni3Sn4 intermetallics formed as a needle-shaped morphology at an early stage and changed into a chunk-shape. Needle-shaped compounds exhibited a higher propensity for spalling than chunk-shaped compounds because many channels among the needle-shaped IMCs facilitated Sn penetration. A reaction between the penetrated Sn and the Ni3P layer formed a Ni3SnP layer and Ni3Sn4 IMCs spalled off the Ni3SnP surface. Dewetting of solder from the Ni3SnP layer, however, did not occur even after spalling of most IMCs.

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Khayyat, Maha M. "Crystalline Silicon Spalling as a Direct Application of Temperature Effect on Semiconductors’ Indentation." Crystals 11, no. 9 (August 25, 2021): 1020. http://dx.doi.org/10.3390/cryst11091020.

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Kerf-less removal of surface layers of photovoltaic materials including silicon is an emerging technology by controlled spalling technology. The method is extremely simple, versatile, and applicable to a wide range of substrates. Controlled spalling technology requires a stressor layer, such as Ni, to be deposited on the surface of a brittle material; then, the controlled removal of a continuous surface layer can be performed at a predetermined depth by manipulating the thickness and stress of the Ni layer, introducing a crack near the edge of the substrate, and mechanically guiding the crack as a single fracture front across the surface. However, spalling Si(100) at 300 K (room temperature RT) introduced many cracks and rough regions within the spalled layer. These mechanical issues make it difficult to process these layers of Si(100) for PV, and in other advanced applications, Si does not undergo phase transformations at 77 K (Liquid Nitrogen Temperature, LNT); based on this fact, spalling of Si(100) has been carried out. Spalling of Si(100) at LNT improved material quality for further designed applications. Mechanical flexibility is achieved by employing controlled spalling technology, enabling the large-area transfer of ultrathin body silicon devices to a plastic substrate at room temperature.

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Choi, Pangil, Lochana Poudyal, Fouzieh Rouzmehr, and Moon Won. "Spalling in Continuously Reinforced Concrete Pavement in Texas." Transportation Research Record: Journal of the Transportation Research Board 2674, no. 11 (September 10, 2020): 731–40. http://dx.doi.org/10.1177/0361198120948509.

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The performance of continuously reinforced concrete pavement (CRCP) in Texas has been quite satisfactory, primarily thanks to the continuous improvements in design and construction. However, severe spalling has been a major problem, and the Texas Department of Transportation (TxDOT) has sponsored several research projects since 1985 to identify solutions for this serious problem. Even though the research efforts were successful in identifying spalling mechanisms, developing a policy that TxDOT could easily implement has been a challenge. To develop a more practical solution to this problem, TxDOT initiated a research study, and the research efforts consisting of identifying CRCP projects with severe and no spalling, obtaining and conducting materials testing on concrete cores from those projects, analyzing the testing data, and performing theoretical analyses to validate the testing results. Among the material properties evaluated, the coefficient of thermal expansion (CTE) of concrete proved to have the best correlation with spalling. Detailed analyses of mechanistic behavior of concrete conducted with an object-oriented finite element program (OOF2) and commercial finite element program verified the reasonableness of the field-testing results. All concrete cores from CRCP with severe spalling had a CTE larger than 5.5 microstrains/°F, whereas no spalling was observed in concrete with a CTE less than that value. Based on this finding, TxDOT now requires the use of coarse aggregate that will produce concrete with a CTE of less than 5.5 microstrains/°F for CRCP construction. It is expected that this implementation will reduce the spalling in CRCP substantially.

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Wang, Ligang, and Dan G. Zollinger. "Mechanistic Design Framework for Spalling Distress." Transportation Research Record: Journal of the Transportation Research Board 1730, no. 1 (January 2000): 18–24. http://dx.doi.org/10.3141/1730-03.

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Spalling is a distress form in concrete pavements that often manifests as the breakdown of the joint of a slab within 15 cm (6 in.) of the joint or crack and can occur at both longitudinal and transverse joints. Efforts have been under way at Texas A&M University to formulate mechanistic spalling models derived from data gathered in recent Texas Department of Transportation studies related to spall development. Extensive field studies have led to the establishment of a spalling mechanism consisting of a step-by-step process that can be characterized with engineering mechanics. These findings indicate that spalling is the result of damage initiated in the form of a shear delamination that is oriented parallel to and at a shallow depth below the surface of the pavement. Conditions necessary for formation of the delaminations include low interfacial strength between the aggregate and mortar and sufficient evaporation of pore water from the hydrating concrete, resulting in differential drying shrinkage near the pavement surface. Delaminations have been noted to initiate early in the life of the pavement and, once formed, extend later into spalls as a result of incompressibles, freeze-thaw cycles, traffic loading, and other such effects. A design framework for delamination formation and subsequent spalling development is presented in a practical format in which to mechanistically design concrete pavement systems relative to spalling distress.

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32

Liu, Hai Yuan, Hou Sheng Jia, Long Fan, and Bin Han. "The Theory and Practice of Forepoling Pre-Stressed System Bolt in Preventing the Rib Spalling." Advanced Materials Research 734-737 (August 2013): 883–87. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.883.

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Based on the particularity of loose and broken of the surrounding rock of roadway, there will be rib spalling after excavating of roadway without support problem. Through analyzing for the specific reasons of the rib spalling, the theory of forepoling pre-stressed system and forepoling support project were put forward. The broken rock zone test in normal roadway support indicating that this technology can effectively prevent the rib spalling before and after digging, having good supporting effect and economic benefits.

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33

Ding, Yan, and Neville F. Rieger. "Spalling formation mechanism for gears." Wear 254, no. 12 (November 2003): 1307–17. http://dx.doi.org/10.1016/s0043-1648(03)00126-1.

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Norton, F. H. "DISCUSSION ON “THEORY OF SPALLING”*." Journal of the American Ceramic Society 16, no. 1-12 (October 17, 2006): 423–24. http://dx.doi.org/10.1111/j.1151-2916.1933.tb19257.x.

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35

Savenkov, G. G. "Fractal cluster model of spalling." Technical Physics 47, no. 12 (December 2002): 1529–32. http://dx.doi.org/10.1134/1.1529942.

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Khare, Saharash, O. P. Singh, K. Bapanna Dora, and C. Sasun. "Spalling investigation of connecting rod." Engineering Failure Analysis 19 (January 2012): 77–86. http://dx.doi.org/10.1016/j.engfailanal.2011.09.007.

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37

Czarnota, C., S. Mercier, and A. Molinari. "Modelling of spalling in tantalum." Journal de Physique IV (Proceedings) 134 (July 26, 2006): 63–68. http://dx.doi.org/10.1051/jp4:2006134011.

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38

Bedell, Stephen W., Keith Fogel, Paul Lauro, Davood Shahrjerdi, John A. Ott, and Devendra Sadana. "Layer transfer by controlled spalling." Journal of Physics D: Applied Physics 46, no. 15 (March 21, 2013): 152002. http://dx.doi.org/10.1088/0022-3727/46/15/152002.

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39

Martini, R., M. Gonzalez, F. Dross, A. Masolin, J. Vaes, D. Frederickx, and J. Poortmans. "Epoxy-Induced Spalling of Silicon." Energy Procedia 27 (2012): 567–72. http://dx.doi.org/10.1016/j.egypro.2012.07.111.

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40

Stump, D. M. "Spalling in zirconia-reinforced ceramics." Mechanics of Materials 20, no. 4 (June 1995): 305–13. http://dx.doi.org/10.1016/0167-6636(94)00065-4.

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41

Bobkova, N. M., L. M. Silich, E. M. Kurpan, and S. A. Gailevich. "Spalling resistant glass-ceramic materials." Glass and Ceramics 44, no. 4 (April 1987): 160–62. http://dx.doi.org/10.1007/bf00701656.

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Cherif, Guergah, Dimia Mohamed Salah, and Benmarce Abdelaziz. "Numerical Modelling of One-Way Reinforced Concrete Slab in FireTaking Into Account of Spalling." Civil Engineering Journal 7, no. 3 (March 3, 2021): 477–87. http://dx.doi.org/10.28991/cej-2021-03091667.

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This paper presents a study of the behaviour of Reinforced Concrete (RC) slabs subjected to severe hydrocarbon fire exposure. In which the spalling phenomena of concrete is to be considered. The hydrocarbon curve is applicable where small petroleum fires might occur, i.e. car fuel tanks, petrol or oil tankers, certain petro-chemical facilities, tunnels, parking structures, etc. Spalling is included using a simplified approach where elements with temperatures higher than 400 °C are assumed to occur and the corresponding thermo-mechanical response of RC slabs is evaluated. The nonlinear finite element software SAFIR has been used to perform a numerical analysis of the spalling risk, by removing layers of concrete covering when a set of spalling criteria is checked. The numerical results obtained by finite element analysis of the temperature distribution within the slab and mid-span deflection were compared with published experimental data. Predictions from the numerical model show a good agreement with the experimental data throughout the entire fire exposure to the hydrocarbon fire. This shows that this approach (layering procedure) is very useful in predicting the behaviour of concrete spalling cases. Doi: 10.28991/cej-2021-03091667 Full Text: PDF

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43

Tsai, M. H., Y. W. Lin, H. Y. Chuang, and C. R. Kao. "Effect of Sn concentration on massive spalling in high-Pb soldering reaction with Cu substrate." Journal of Materials Research 24, no. 11 (November 2009): 3407–11. http://dx.doi.org/10.1557/jmr.2009.0398.

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The massive spalling of Cu3Sn in the soldering reaction between high-Pb solders and Cu substrates was studied to identify the mechanism behind this rather interesting and frequently observed phenomenon. Four different alloys (99.5 Pb 0.5 Sn, 99 Pb 1S n, 97 Pb 3 Sn, and 95 Pb 5 Sn, in wt%) were soldered at 350 °C for durations ranging from 10 s to 600 min. At low Sn concentration (0.5 or 1 Sn), massive spalling occurred as early as 20 min. However, at high Sn concentration (3 or 5 Sn), massive spalling was not completed even after 600 min. To the best of our knowledge, these results are the most detailed observations ever reported on the sequence of events that occur during massive spalling. The Pb–Sn–Cu phase diagram is used to rationalize the phenomenon.

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Hajihasani, Nadia, and Norhisham Bakhary. "Detection of Concrete Spalling Using Changes in Modal Flexibility." Advanced Materials Research 163-167 (December 2010): 2598–602. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.2598.

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This paper presents a study in the effect of spalling to dynamic parameters such as natural frequencies and mode shapes. Numerical example of a slab is used as an example in this study. The slab will be modelled using ANSYS 11.0 and various types of spalling are imposed. The changes of vibration parameters are monitored and compared. To compare the sensitivity of modal parameters to spalling is determined using the flexibility method. Based on the results it is found that by incorporating mode shapes using flexibility method, damage location and severity can be obtained.

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Ozawa, Mitsuo, Zhou Bo, Yuichi Uchida, and Hiroaki Morimoto. "Preventive Effects of Fibers on Spalling of UFC at High Temperatures." Journal of Structural Fire Engineering 5, no. 3 (August 19, 2014): 229–38. http://dx.doi.org/10.1260/2040-2317.5.3.229.

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This paper investigates the relationship between spalling behavior and weight loss for ultra-high-strength fiber-reinforced concrete (UFC) containing different types short fibers (jute, PP, WSPVA) in high-temperature environments at 400, 600 and 800 °C. The explosive spalling that occurred under these conditions caused severe damage to the control specimen but only slight damage to the specimen with jute fiber. It was therefore inferred that adding 0.19% by volume of natural jute fibers (length: 12 mm) to UFC is effective in the prevention of spalling-related damage.

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46

Williams, R. E., R. M. Potter, and S. Miska. "Experiments in Thermal Spallation of Various Rocks." Journal of Energy Resources Technology 118, no. 1 (March 1, 1996): 2–8. http://dx.doi.org/10.1115/1.2792690.

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The greatest limitation of the spallation process is its inability to spall (or to consistently spall) many rocks encountered in petroleum drilling and mining operations. The New Mexico Institute of Mining and Technology has conducted a series of experiments to investigate the possibility of expanding the use of the spallation process to the penetration of rocks generally considered not to be spallable. The methods used during this work were 1) spalling at temperatures below that produced by the stoichiometric burning of fuel oil and air, and 2) spalling by alternately heating and quenching the rock surfaces. No success was experienced in spalling at the lower temperatures, but initial tests showed the alternate heating and chilling system to be successful, particularly in penetrating travertine limestone. However, continued testing indicated that, unless the rocks are extremely uniform in composition, spalling will result in highly irregular holes or holes that cannot be directionally controlled.

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Wu, Hangbin, Xingran Ao, Zhuo Chen, Chun Liu, Zeran Xu, and Pengfei Yu. "Concrete Spalling Detection for Metro Tunnel from Point Cloud Based on Roughness Descriptor." Journal of Sensors 2019 (May 2, 2019): 1–12. http://dx.doi.org/10.1155/2019/8574750.

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Automatic concrete spalling detection has become an important issue for metro tunnel examinations and maintenance. This paper focuses on concrete spalling detection research with surface roughness analysis based on point clouds produced by 3D mobile laser scanning (MLS) system. In the proposed method, at first, the points on ancillary facilities attached to tunnel surface are considered as outliers and removed via circular scan-line fitting and large residual error filtering. Then, a roughness descriptor for the metro tunnel surface is designed based on the triangulated grid derived from point clouds. The roughness descriptor is generally defined as the ratio of surface area to the projected area for a unit, which works well in identifying high rough areas on the tunnel surface, such as bolt holes, segment seams, and spalling patches. Finally, rough area classification based on Hough transformation and similarity analysis is performed on the identified areas to accurately label patches belonging to segment seams and bolt holes. After removing the patches of bolt holes and segment seams, the remaining patches are considered as belonging to concrete spalling. The experiment was conducted on a real tunnel interval in Shanghai. The result of concrete spalling detection revealed the validity and feasibility of the proposed method.

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48

Yang, Juan, and Gai Fei Peng. "The Mechanism of Explosive Spalling and Measures to Resistant Spalling of Concrete Exposed to High Temperature by Incorporating Fibers: A Review." Advanced Materials Research 168-170 (December 2010): 773–77. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.773.

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Many experimental researches have been conducted on explosive spalling performance of concrete of high-strength / high performance concrete (HSC/HPC). This paper summarizes two main explosive spalling mechanisms (Vapor pressure build-up mechanism and Thermal stress mechanism) of concrete at elevated temperature, and also presents the measures to resistant the explosive spalling, i.e. by incorporating fibers (polypropylene fiber(PPF), steel fiber(SF) and hybrid fiber of the first two). Finally, the further studies of both the mechanism and the measures are proposed. Also, the preliminary study of ultra high-strength concrete (UHSC) on fire-resistance are mentioned.

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Lee, Taegyu, Gyuyong Kim, Gyeongcheol Choe, Euichul Hwang, Jaesung Lee, Dongwoo Ryu, and Jeongsoo Nam. "Spalling Resistance of Fiber-Reinforced Ultra-High-Strength Concrete Subjected to the ISO-834 Standard Fire Curve: Effects of Thermal Strain and Water Vapor Pressure." Materials 13, no. 17 (August 27, 2020): 3792. http://dx.doi.org/10.3390/ma13173792.

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The prevention and mitigation of spalling in high-strength concrete (HSC) rely on mixing polypropylene (PP) as an additive reinforcement. The dense internal structures of ultra-high-strength concrete (UHSC) result in risks associated with a high thermal stress and high water vapor pressure. Herein, the effects of pore formation and thermal strain on spalling are examined by subjecting fiber-laden UHSC to conditions similar to those under which the ISO-834 standard fire curve was obtained. Evaluation of the initial melting properties of the fibers based on thermogravimetric analysis (TGA) and differential thermal analysis (DTA) demon strated that although nylon fibers exhibit a higher melting point than polypropylene and polyethylene fibers, weight loss occurs below 200 °C. Nylon fibers were effective at reducing spalling in UHSC compared to polypropylene and polyethylene fibers as they rapidly melt, leading to pore formation. We anticipate that these results will serve as references for future studies on the prevention of spalling in fiber-reinforced UHSC.

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Sohn, Yoon-Chul, and Jin Yu. "Correlation Between Chemical Reaction and Brittle Fracture Found in Electroless Ni(P)/immersion gold–solder Interconnection." Journal of Materials Research 20, no. 8 (August 1, 2005): 1931–34. http://dx.doi.org/10.1557/jmr.2005.0246.

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Occurrence of brittle interfacial fracture at an electroless Ni(P)/immersion gold–solder joint has long been a serious problem not yet fully understood. In our previous report on the electroless Ni(P) [J. Mater. Res.19,2428 (2004)], it was shown that crystallization of the Ni(P) film and growth of the Ni3SnP layer were accelerated after the intermetallic compound (IMC) spalling, and accurate failure locus of the brittle fracture due to so-called “IMC spalling induced microstructure degradation of the Ni(P) film” is presented for the first time in this communication. For Sn–3.0Ag–0.5Cu solder joints, (Ni,Cu)3Sn4and/or (Cu,Ni)6Sn5ternary IMCs formed at the interface, and neither spalling nor interfacial fracture was observed. For Sn–3.5Ag joints, Ni3Sn4compound formed, and the brittle fracture occurred through the Ni3SnP layer in the solder pads where Ni3Sn4had spalled. Since the Ni3SnP layer is getting thicker during or after Ni3Sn4spalling, control of IMC spalling is crucial to ensure the reliability of Ni(P)/solder system.

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Journal articles on the topic 'Spallings'

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