Journal articles: 'Spalling of concrete matrix'

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Zhu, Hehua, Xiangyang Wei, J. Woody Ju, Qing Chen, Zhiguo Yan, and Yi Shen. "Statistical micromechanical damage model for SH-SFRC under tensile load considering the interfacial slip-softening and matrix spalling effects." International Journal of Damage Mechanics 30, no. 9 (April 20, 2021): 1423–49. http://dx.doi.org/10.1177/10567895211011225.

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Strain hardening behavior can be observed in steel fiber reinforced concretes under tensile loads. In this paper, a statistical micromechanical damage framework is presented for the strain hardening steel fiber reinforced concrete (SH-SFRC) considering the interfacial slip-softening and matrix spalling effects. With a linear slip-softening interface law, an analytical model is developed for the single steel fiber pullout behavior. The crack bridging effects are reached by averaging the contribution of the fibers with different inclined angles. Afterwards, the traditional snubbing factor is modified by considering the fiber snubbing and the matrix spalling effects. By adopting the Weibull distribution, a statistical micromechanical damage model is established with the fracture mechanics based cracking criteria and the stress transfer distance. The comparison with the experimental results demonstrates that the proposed framework is capable of reproducing the SH-SFRC’s uniaxial tensile behavior well. Moreover, the impact of the interfacial slip-softening and matrix spalling effects are further discussed with the presented framework.

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Rohden, Abrahão Bernardo, Jessica Regina Camilo, Rafaela Cristina Amaral, Estela Oliari Garcez, and Mônica Regina Garcez. "Effects of Plastic Waste on the Heat-Induced Spalling Performance and Mechanical Properties of High Strength Concrete." Materials 13, no. 15 (July 23, 2020): 3262. http://dx.doi.org/10.3390/ma13153262.

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This paper investigates a potential application of hard-to-recycle plastic waste as polymeric addition in high strength concrete, with a focus on the potential to mitigate heat-induced concrete spalling and the consequent effects on the mechanical properties. The waste corresponds to soft and hard plastic, including household polymers vastly disposed of in landfills, although technically recyclable. Mechanical and physical properties, cracking, mass loss, and the occurrence of spalling were assessed in high strength concrete samples produced with either plastic waste or polypropylene fibers after 2-h exposure to 600 °C. The analysis was supported by Scanning Electron Microscopy and X-Ray Computed Tomography images. The plastic waste is composed of different polymers with a thermal degradation between 250 to 500 °C. Polypropylene (PP) fibers and plastic waste dispersed in concrete have proved to play an essential role in mitigating heat-induced concrete spalling, contributing to the release of internal pressure after the polymer melting. The different morphology of plastic waste and polypropylene fibers leads to distinct mechanisms of action. While the vapor pressure dissipation network originated by polypropylene fibers is related to the formation of continuous channels, the plastic waste seems to cause discontinuous reservoirs and fewer damages into the concrete matrix. The incorporation of plastic waste improved heat-induced concrete spalling performance. While 6 kg/m3 of plastic increased the mechanical performance after exposure to high temperature, the incorporation of 3 kg/m3 resulted in mechanical properties comparable to the reference concrete.

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Diederichs, Ulrich, Iris Marquardt, and Vít Petranek. "Rehydration of Ultra High Performance Concrete." Advanced Materials Research 897 (February 2014): 275–79. http://dx.doi.org/10.4028/www.scientific.net/amr.897.275.

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Ultra High Performance Concrete (UHPC) and High Strength Concrete (USC) are because of the high density of their matrices very susceptible to spalling during fire exposure. By aid of a heat treatment with maximum temperatures of about 450°C a network of capillaries and micro cracks could be formed, which leads like a porous medium to a relief of water vapor already at harmless low pressures and could prevent the materials from spalling. In the framework of the presented study on UHPC some orientating tests have been performed to obtain knowledge concerning alterations of the microstructure during thermal treatment at 150°C, 250°C, 350°C and 450°C and the subsequent storage in air with 100% relative humidity at 20°C as to allow water uptake and rehydration. The tests have shown that by aid of the said treatment generation of a respective porous system was achieved, which remained open for the transport of water vapor at high temperatures, also after water uptake and rehydration of the dehydrated cementitious matrix. However further studies are needed to get information about effects of the treatments on the mechanical properties and the durability of members.

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Cao, Y. Y. Y., Q. L. Yu, and H. J. H. Brouwers. "Effects of Inclination Angle on Pullout Performance of Hooked End Fiber Embedded in UHPC." Key Engineering Materials 812 (July 2019): 60–65. http://dx.doi.org/10.4028/www.scientific.net/kem.812.60.

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Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) is a material with superior mechanical strength and energy absorption capacity. The orientation of the fiber and the fiber-matrix bond relationship are important factors that affect the performance of UHPFRC. In this study, the pullout performances of hooked end fibers embedded in ultra-high performance concrete (UHPC) matrix under various inclination angles are investigated. It is shown that for the tested fiber and UHPC matrix, the optimum angle for reaching the maximum pullout energy is around 10 degrees; when the inclination angle further increases fiber rupture and matrix spalling occur more frequently. Results from this study can contribute to a better understanding and utilization of fibers effects in UHPFRC.

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Guo, Liping, Wenxiao Zhang, Wei Sun, Bo Chen, and Yafan Liu. "High-Temperature Performance and Multiscale Damage Mechanisms of Hollow Cellulose Fiber-Reinforced Concrete." Advances in Materials Science and Engineering 2016 (2016): 1–14. http://dx.doi.org/10.1155/2016/2503780.

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Spalling resistance properties and their damage mechanisms under high temperatures are studied in hollow cellulose fiber-reinforced concrete (CFRC) used in tunnel structures. Measurements of mass loss, relative dynamic elastic modulus, compressive strength, and splitting tensile strength of CFRC held under high temperatures (300, 600, 800, and 1050°C) for periods of 2.5, 4, and 5.5 h were carried out. The damage mechanism was analyzed using scanning electron microscopy, mercury intrusion porosimetry, thermal analysis, and X-ray diffraction phase analysis. The results demonstrate that cellulose fiber can reduce the performance loss of concrete at high temperatures; the effect of holding time on the performance is more noticeable below 600°C. After exposure to high temperatures, the performance of ordinary concrete deteriorates faster and spalls at 700–800°C; in contrast, cellulose fiber melts at a higher temperature, leaving a series of channels in the matrix that facilitate the release of the steam pressure inside the CFRC. Hollow cellulose fibers can thereby slow the damage caused by internal stress and improve the spalling resistance of concrete under high temperatures.

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Benin, Andrey, Matija Guzijan-Dilber, Leonid Diachenko, and Artem Semenov. "Finite element simulation of a motorway bridge collapse using the concrete damage plasticity model." E3S Web of Conferences 157 (2020): 06018. http://dx.doi.org/10.1051/e3sconf/202015706018.

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The aim of this work is to show how the concrete damage plasticity model developed by Lubliner et al. can be applied for calculation of a motorway bridge collapse occurred in the Amur region, Russia. The concrete structural behaviour is highly complex. Being a quasi-brittle material, concrete demonstrates softening behaviour that is numerically complex due to the loss of positive definiteness of the tangent rigidity matrix of the material, and hence the loss of the ellipticity of the equilibrium rate equation. This eventually leads to the loss of well-posedness of the rate boundary value problem. Besides that, concrete behaviour in compression differs from that in tension. There are a few different failure modes of concrete material: tension cracking, compression crushing, spalling of concrete, etc.

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Ahmad Mujahid, Ahmad Zaidi, Josef Hadipramana, Abdul Aziz Abdul Samad, and Noridah Mohamad. "Investigation on Impact Resistance Foamed Concrete Reinforced by Polypropylene Fibre." Key Engineering Materials 594-595 (December 2013): 24–28. http://dx.doi.org/10.4028/www.scientific.net/kem.594-595.24.

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Foamed Concrete (FC) needs high strength to prevent dynamic loading, thus it is important to enhance the ductility. Usage the Polypropylene Fibre (PF) examined its contribution in strength of FC on impact resistance. Microstructures were observed that air voids in matrix of FC produce micro-porous that reduce interfacial bonding into matrix and generate micro-crack that may propagation crack growth. Presence of PF in admixture results fibrillation and reduces micro-cracks. Tensile test was investigated that PF delays crack growth in matrix. In this investigation impact test were conducted using an instrumented drop-weight impact tower. When impactor hits the target surface in free surface condition causes compressive plastic wave transform to be tensile wave. It was affected by tensile strength therefore local effect has not found spalling in crater field. In addition influence of porous in matrix FC has ability to absorb the energy and it was not found distal crack around surface area. Penetration depth results showed FC with PF subjected to impact loading was lower than without FC. Presence of PF increases FC strength and local effect results there was not impression of fragments around distal surface due to brittle crushing.

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Scheinherrová, Lenka, Monika Čáchová, Michaela Petříková, Lukáš Fiala, Eva Vejmelková, Stefania Grzeszczyk, and Robert Černý. "Mechanical and Basic Physical Properties of High-Strength Concrete Exposed to Elevated Temperatures." Key Engineering Materials 760 (January 2018): 108–13. http://dx.doi.org/10.4028/www.scientific.net/kem.760.108.

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In this paper, the effect of elevated temperatures on the mechanical and basic properties of two different newly-designed high-strength concretes is studied. The studied materials were prepared from Portland cement, steel fibers, reactive finely milled quartz powder and quartz sand, silica fume, plasticizer, and with a relatively low water/cement ratio of 0.24. The samples were stored in water environment for the first 28 days of hydration to achieve better mechanical properties. Then, after pre-drying at 105 °C to constant mass, the materials were exposed to elevated temperatures of 600 °C and 1000 °C where they were kept for 2 hours. The basic physical properties, such as matrix density, bulk density and open porosity were determined as a function of temperature. Mechanical properties (compressive and flexural strength) were also studied. The measured parameters exhibited a high dependence on temperature and the obtained results pointed to the structural changes of the studied materials. Spalling was not observed because of the pre-drying treatment.

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Abbas, Yassir M. "Microscale Cohesive-Friction-Based Finite Element Model for the Crack Opening Mechanism of Hooked-End Steel Fiber-Reinforced Concrete." Materials 14, no. 3 (February 1, 2021): 669. http://dx.doi.org/10.3390/ma14030669.

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The entire mechanical properties of steel fiber-reinforced concrete (SFRC) are significantly dependent on the fiber–matrix interactions. In the current study, a finite element (FE) model was developed to simulate the pullout response of hooked-end SFRC employing cohesive–frictional interactions. Plain stress elements were adapted in the model to exemplify the fiber process constituents, taking into consideration the material nonlinearity of the hooked-end fiber. Additionally, a surface-to-surface contact model was used to simulate the fiber’s behavior in the pullout mechanism. The model was calibrated against experimental observations, and a modification factor model was proposed to account for the 3D phenomenalistic behavior of the pullout behavior. Realistic predictions were obtained by using this factor to predict the entire pullout-slip curves and independent results for the peak pullout load. The numerical results indicated that the increased fiber diameter would alter the mode of crack opening from fiber–matrix damage to that combined with matrix spalling, which can neutralize the sensitivity of the entire pullout response of hooked-end steel fiber to embedment depth. Additionally, the fiber–matrix bond was enhanced by increasing the fiber’s surface area, sensibly leading to a higher pullout peak load and toughness. The developed FE model was also proficient in predicting microstructural stress distribution and deformations during the crack opening of SFRC. This model could be extended to fully model a loaded SFRC composite material by the inclusion of various randomly oriented dosages of fibers in the concrete block.

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Hoang, Nhat-Duc, Quoc-Lam Nguyen, and Xuan-Linh Tran. "Automatic Detection of Concrete Spalling Using Piecewise Linear Stochastic Gradient Descent Logistic Regression and Image Texture Analysis." Complexity 2019 (July 16, 2019): 1–14. http://dx.doi.org/10.1155/2019/5910625.

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Recognition of spalling on surface of concrete wall is crucial in building condition survey. Early detection of this form of defect can help to develop cost-effective rehabilitation methods for maintenance agencies. This study develops a method for automatic detection of spalled areas. The proposed approach includes image texture computation for image feature extraction and a piecewise linear stochastic gradient descent logistic regression (PL-SGDLR) used for pattern recognition. Image texture obtained from statistical properties of color channels, gray-level cooccurrence matrix, and gray-level run lengths is used as features to characterize surface condition of concrete wall. Based on these extracted features, PL-SGDLR is employed to categorize image samples into two classes of “nonspall” (negative class) and “spall” (positive class). Notably, PL-SGDLR is an extension of the standard logistic regression within which a linear decision surface is replaced by a piecewise linear one. This improvement can enhance the capability of logistic regression in dealing with spall detection as a complex pattern classification problem. Experiments with 1240 collected image samples show that PL-SGDLR can help to deliver a good detection accuracy (classification accuracy rate = 90.24%). To ease the model implementation, the PL-SGDLR program has been developed and compiled in MATLAB and Visual C# .NET. Thus, the proposed PL-SGDLR can be an effective tool for maintenance agencies during periodic survey of buildings.

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Wang, Zhong Qiang, and Zhi Wu Yu. "The Experimental Research and Theoretical Analysis of Unbonded Prestressed Concrete Flat Beams at High Temperature." Advanced Materials Research 250-253 (May 2011): 2242–52. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.2242.

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The experiments of 26 unbonded prestressed concrete flat beams under fire with elevating the temperature according to the ISO time-temperature standard curve were accomplished in the large structures electrical heating furnace that was manufactured independently. The macroscopical phenomena of water penetration, the lube flowing, the spalling of concrete and the corlor change of aspect were observed. The laws of behaviors such as temperature distribution on section,the deformation characteristic and stress varieties of prestressed tendons were investigated through the tests. The experiments indicated that temperature distribution was not uniform, the dynamic continuous deformation and the complicated varieties of prestressed stress occurred at high temperature. Based on the increment temperature-stress coupling constitutive models and chief deformation compatibility of the unboded prestressed tendons, the nonlinear finite element calculation formula took the unknown nodes displacements and the tensile forces in the unbonded tendons as unsolved column matrix simultaneously. The Increment format of nonlinear finite element method and calculation model for whole process analysis of unbonded prestressed concrete flexural members at high temperature were presented. The solution of nonlinear equilibrium equations for unboded prestressed concrete flexural members at high tempure was proposed, and a FORTRAN program named NAUPCLF was developed also and the results were in good agreement. The conclusions can supply the way and basis for further fire-resistant design and analysis of prestressed concrete structures.

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Fořt, Jan, Anton Trník, David Čítek, and Zbyšek Pavlík. "Residual Mechanical Properties of Hybrid Fiber Reinforced HPC Exposed to High Temperatures." Key Engineering Materials 722 (December 2016): 52–58. http://dx.doi.org/10.4028/www.scientific.net/kem.722.52.

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The effect of high temperature load on mechanical properties and porosity of a newly designed Ultra High Performance Fiber Reinforced Concrete (UHPFRC) is studied. The hybrid reinforcement of UHPFRC is based on a mixture of polypropylene and steel fibers. In order to identify influence of high temperature exposure on UHPFRC, its residual mechanical parameters such as compressive strength, flexural strength and Young’s modulus of elasticity are accessed. Moreover, residual bulk density, matrix density and total open porosity are examined and related to the monitored structural changes. Simultaneous Thermal Analysis (STA) is employed in order to describe transformation processes during high temperature loading. The conducted tests provide practical information for controlled regulation of water vapor transport in a low permeable cementitious composite in order to decrease risk of spalling.

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Samad, Abdul Aziz Abdul, Josef Hadipramana, Ahmad Zaidi Ahmad Mujahid, and Noridah Mohamad. "Investigation on Energy Absorption of Slab Foamed Concrete Reinforced by Polypropylene Fibre Subjected to Impact Loading." Advanced Materials Research 831 (December 2013): 67–72. http://dx.doi.org/10.4028/www.scientific.net/amr.831.67.

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Polypropylene Fibre (PF) as reinforcement has contributed to the intensity of Foamed Concrete (FC) slab when subjected to impact loading. The presence of PF in the admixture reduces the micro-porosity that generates the micro-crack of the slab. However, the fibrillation of PF in the admixture enhances the bonding mechanism system between PF and the FC matrix. The impact test conducted uses an instrumented drop-weight impact tower. Results show that FC without PF produces a distinct radial crack and clear fragments within the crater field unlike FC with PF. However, both slab materials did not generate spalling nor scabbing upon impact and the influence of porosity produces only local damage due to the mechanism of brittle crushing effect of porous walls. In this study, the energy absorption between FC with and without PF was investigated and from observation produces only minor differences. Results also verify that FC with PF did not loss its ability to absorb energy upon impact.

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Buttignol, T. E. T., J. L. A. O. Sousa, and T. N. Bittencourt. "Ultra High-Performance Fiber-Reinforced Concrete (UHPFRC): a review of material properties and design procedures." Revista IBRACON de Estruturas e Materiais 10, no. 4 (August 2017): 957–71. http://dx.doi.org/10.1590/s1983-41952017000400011.

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ABSTRACT This paper does a review of the recent achievements on the knowledge of UHPFRC properties and in the development of design procedures. UHPFRC is defined as a new material, with unique properties (high ductility, low permeability, very high strength capacity in compression, higher toughness) in comparison to conventional concrete. It is important to know both material and mechanical properties to fully take advantage of its outstanding properties for structural applications. However, since this is a new material, the current design codes are not well suited and should be reviewed before being applied to UHPFRC. In the first part, the following material properties are addressed: hydration process; permeability; fibers role; mix design; fiber-matrix bond properties workability; mixing procedure; and curing. In the second part, the mechanical properties of the material are discussed, together with some design recommendations. The aspects herein examined are: size effect; compressive and flexural strength; tensile stress-strain relation; shear and punching shear capacity; creep and shrinkage; fracture energy; steel bars anchorage and adherence. Besides, the tensile mechanical characterization is described using inverse analysis based on bending tests data. In the last part, material behavior at high temperature is discussed, including physical-chemical transformations of the concrete, spalling effect, and transient creep. In the latter case, a new Load Induced Thermal Strain (LITS) semi-empirical model is described and compared with UHPC experimental results.

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Han, Aylie, Buntara Sthenly Gan, Rudi Yuniarto, Anastasia Yesica, and Rakhma Nurfitriani Editia. "Inclusion-to-Specimen Volume Ratio Influence on the Strength and Stiffness Behaviors of Concrete: An Experimental Study." Applied Mechanics and Materials 845 (July 2016): 113–18. http://dx.doi.org/10.4028/www.scientific.net/amm.845.113.

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The stress-strain response of the basic concrete making material, i.e. the mortar and aggregates, are well known. In general, the aggregate behaves linearly up till failure, possessing a very high ultimate compression strength and stiffness. The behavior of mortar is non-linear, even at low loading levels. The resulting composite material, the concrete, exhibits a less stiff response, in combination with degradation in strength. This study looked into the influence of the inclusion-to-specimen volume ratio of a 100x100x50 mm mortar specimen. Two inclusion configurations were considered, parallel and diagonal to the line of loading, while the ratio varied from zero to 0.66. It was shown that the inclusion-to-specimen volume ratio strongly influenced the strength, the stiffness, and failure mode. The strength behavior had a minimum and a maximum bifurcation point, while the stiffness response increased, as a function of an increase in the inclusion-to-specimen volume ratio. Visual observation of the cracking pattern revealed that the initial cracking was always situated at the interface between the aggregate and mortar in tension and propagated through the mortar matrix. It was also perceived that the crack propagation path of the very dense, diagonally arranged inclusions deviated from the columnar configuration observed from the parallel inclusion formation. These densely diagonally arranged aggregates also resulted in spalling in the lateral direction.

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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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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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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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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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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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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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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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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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Zollinger, Dan G., Sanjaya P. Senadheera, and Tianxi Tang. "Spalling of Continuously Reinforced Concrete Pavements." Journal of Transportation Engineering 120, no. 3 (May 1994): 394–411. http://dx.doi.org/10.1061/(asce)0733-947x(1994)120:3(394).

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Xiong, Wei, Bo Wu, and Bo Wen. "Spalling of concrete cover of cyclically loaded columns and fire behaviour of columns with concrete spalling." Structure and Infrastructure Engineering 12, no. 12 (March 8, 2016): 1537–52. http://dx.doi.org/10.1080/15732479.2016.1151055.

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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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Chang, Chuan Peng, Shi Wu Huang, Xue Feng Li, Bo Tian, and Zi Yi Hou. "A Study of the Capability for Fire Resistance of Polypropylene Fibre Concrete." Advanced Materials Research 857 (December 2013): 116–23. http://dx.doi.org/10.4028/www.scientific.net/amr.857.116.

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The purpose of this paper is to examine the effect of various polypropylene fibre additions (length and content) to concrete on compressive strength and explosive spalling when subjected to high temperatures, which simulate the building or tunnel fires. The experimental results show that the compressive strength of polypropylene fiber concrete (PFC) and plain concrete decreases with increasing temperature. Fibre content in a certain range has a small effect on the compressive strength of the concrete, therefore the polypropylene (PP) fibers has a great influence on the anti-spalling behavior of concrete under fire loading to ensure the integrity of the structure. Keywords: concrete, polypropylene fibre, high temperature, compressive strength, spalling

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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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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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Hager, Izabela, Katarzyna Mróz, and Tomasz Tracz. "Concrete propensity to fire spalling: testing and observations." MATEC Web of Conferences 163 (2018): 02004. http://dx.doi.org/10.1051/matecconf/201816302004.

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This article presents results of fire spalling tests on small concrete slabs and studies of material parameters that may increase its occurrence. Experimental techniques enabling to study and determination of material features are presented and discussed. Experimental studies on spalling behaviour of elements were carried out on seven different concrete mixes with constant content of cement paste and mortar. Research aimed at determining influence of the following parameters: w/c ratio (0.30; 0.45; 0.60), cement type (CEM I, CEM III) and type of aggregates (riverbed gravel, granite, basalt) on fire concrete spalling. Paper discusses also the influence of cold rim that forms while testing slab-like element is subjected to one-side heating.

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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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Peng, Gai Fei, and Yan Teng. "Fire Resistance of Ultra-High-Strength Concrete: a Review." Key Engineering Materials 477 (April 2011): 333–39. http://dx.doi.org/10.4028/www.scientific.net/kem.477.333.

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This paper presents a review of advances in research on fire resistance of high-strength concrete (HSC) and ultra-high-strength concrete (UHSC). Further research needs in the near future on UHSC, especially on reactive powder concrete (RPC), are also discussed. It is commonly recognized that HSC suffers strength loss in a manner basically similar to that of normal strength concrete. But the main problem of HSC is explosive spalling under high temperature, which can be solved by employing either polymer fiber or steel fiber. Since RPC200 is a type of RPC which has been successfully prepared in many counties and is to be applied to engineering practice, fire resistance of RPC200 needs a series of investigations urgently. The objectives of such investigations are to restrain explosive spalling and minimizing spalling probability, so as to ensure satisfactory fire resistance of RPC. It is expected that a research will be carried out on explosive spalling behavior, fracture properties, and micro-structure, to establish a mechanism as well as technical measures for improving fire resistance of RPC.

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Zhang, Li, Ya Wei, Francis Tat Kwong Au, and Jing Li. "Experimental study of two-way post-tensioned flat slabs in fire." Journal of Structural Fire Engineering 9, no. 3 (September 10, 2018): 237–51. http://dx.doi.org/10.1108/jsfe-01-2017-0016.

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Purpose This study aims to investigate the influence of tendon layout, pre-stressing force, bond condition and concrete spalling on the structural behaviour of two-way post-tensioned flat slabs at elevated temperatures. Design/methodology/approach Fire tests of four scale specimens of two-way post-tensioned concrete flat slabs were performed and analysed. Three of them were provided with bonded tendons, while the other was unbonded for comparison. The fabrication of specimens, phenomena observed during testing, temperature distributions, deflections and occurrence of concrete spalling were examined. Findings Different degrees of concrete spalling observed at the soffit had significant effects on the temperature distribution and stress redistribution. This was the major reason for the progressive concrete spalling observed, resulting in loss of structural integrity and stiffness. Originality/value The structural behaviour of two-way post-tensioned concrete flat slabs at elevated temperatures is less understood compared to their one-way counterparts. Therefore, the present study has focused on the structural behaviour of two-way post-tensioned concrete flat slabs with bonded tendons in fire, a field in which relatively little information on experimental work can be found.

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Kodur, Venkatesh, and Monther Dwaikat. "Fire-induced spalling in reinforced concrete beams." Proceedings of the Institution of Civil Engineers - Structures and Buildings 165, no. 7 (July 2012): 347–59. http://dx.doi.org/10.1680/stbu.11.00013.

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36

Hertz, K. D. "Limits of spalling of fire-exposed concrete." Fire Safety Journal 38, no. 2 (March 2003): 103–16. http://dx.doi.org/10.1016/s0379-7112(02)00051-6.

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37

Smith, Frederick P. "Concrete spalling: controlled fire tests and review." Journal of the Forensic Science Society 31, no. 1 (January 1991): 67–75. http://dx.doi.org/10.1016/s0015-7368(91)73119-8.

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38

Rollings, Raymond S. "Joint Spalling in Newly Constructed Concrete Pavements." Journal of Performance of Constructed Facilities 12, no. 3 (August 1998): 137–44. http://dx.doi.org/10.1061/(asce)0887-3828(1998)12:3(137).

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Rollings, Raymond S., Jerry P. Burkes, Michael I. Hammons, G. Sam Wong, and Marian P. Rollings. "Investigation of Joint Spalling on Concrete Runway." Journal of Performance of Constructed Facilities 12, no. 1 (February 1998): 12–19. http://dx.doi.org/10.1061/(asce)0887-3828(1998)12:1(12).

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40

Jansson, R. "Fire spalling of concrete – A historical overview." MATEC Web of Conferences 6 (2013): 01001. http://dx.doi.org/10.1051/matecconf/20130601001.

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41

Foglar, M., and M. Kovar. "Spalling of concrete subjected to blast loading." MATEC Web of Conferences 6 (2013): 07005. http://dx.doi.org/10.1051/matecconf/20130607005.

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42

Phan, Long T. "Pore pressure and explosive spalling in concrete." Materials and Structures 41, no. 10 (January 18, 2008): 1623–32. http://dx.doi.org/10.1617/s11527-008-9353-2.

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43

Zhang, L., S. S. Hu, D. X. Chen, Z. Q. Yu, and F. Liu. "An Experimental Technique for Spalling of Concrete." Experimental Mechanics 49, no. 4 (July 26, 2008): 523–32. http://dx.doi.org/10.1007/s11340-008-9159-8.

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44

Lalu, O., R. Darmon, and T. Lennon. "Spalling of high strength concrete in fire." IOP Conference Series: Materials Science and Engineering 1138, no. 1 (April 1, 2021): 012027. http://dx.doi.org/10.1088/1757-899x/1138/1/012027.

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Moccia, Francesco, Miguel Fernández Ruiz, and Aurelio Muttoni. "Spalling of concrete cover induced by reinforcement." Engineering Structures 237 (June 2021): 112188. http://dx.doi.org/10.1016/j.engstruct.2021.112188.

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46

Nguyen, Kate TQ, Tuan Ngo, Priyan Mendis, and David Heath. "Performance of high-strength concrete walls exposed to fire." Advances in Structural Engineering 21, no. 8 (September 26, 2017): 1173–82. http://dx.doi.org/10.1177/1369433217732500.

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High-strength concrete is becoming very popular around the world due to its many advantages over normal-strength concrete. There are significant behavioural differences between high-strength concrete and normal-strength concrete, most notably the brittleness and sudden spalling under elevated temperatures, whereby pieces of hardened concrete explosively dislodge. Although all high-rise and even many medium-rise buildings have high-strength concrete walls, the spalling of high-strength concrete walls in fire has generally been ignored by the designers and the fire resistance of walls has been calculated using the rules specified for normal-strength concrete. Catastrophic failures could occur due to this ignorance of an important issue. Major design codes including the American and Australian Codes do not cover spalling adequately. Even the Eurocode rules are based on limited research. After a brief discussion on the present design practice, this article presents a summary of spalling research. The relevant results from a comprehensive study conducted at the University of Melbourne are briefly discussed. The authors are not aware of any other comprehensive research projects covering the fire behaviour of normal-strength concrete and high-strength concrete walls exposed not only to standard fires but also hydrocarbon fires. The results showed that spalling in high-strength concrete is more significant when subjected to hydrocarbon fire compared to normal-strength concrete. The level of compressive load on the panels was also found to have a significant effect on the fire performance of the high-strength concrete panels. The finite analysis element program, ANSYS, was used to model the concrete walls subjected to load and fire (both ISO834 Standard fire and hydrocarbon fire). The test results were used to validate the computer model.

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Eratodi, I. Gusti Lanang Bagus, Ali Awaludin, Ay Lie Han, and Andreas Triwiyono. "Evaluation and Study of Prestressed Slab Structure Precast Modular Concrete." MEDIA KOMUNIKASI TEKNIK SIPIL 26, no. 1 (July 30, 2020): 44–51. http://dx.doi.org/10.14710/mkts.v26i1.27765.

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Prestressed precast modular concrete slabs function rigid pavement, supporting vehicle loads above it on subgrade with relatively low bearing capacity. This slab measures 2000 x 850 x 150 mm3 of regular reinforced concrete (old production) or prestressed concrete (new production) quality K-500. After several times of use, damage occurs mainly at the end of the slab in the form of spalling. The objectives of the study and evaluation were: (1) observing damage; (2) material quality data; (3) numerical modeling by taking into account material properties, loading and soil conditions; and (4) providing slab design recommendations including materials and geometrics. The method of study and evaluation of slab damage was done by observing the damage, taking concrete core-case and testing it in the laboratory, and modeling the slab structure with various parameters (soil data, concrete quality and slab geometry). Field observations and analysis results show that concrete slab spalling occurs initially at the edge (850 mm wide) which in turn causes the effectiveness of the pre-tension force to be suboptimal and finally the concrete spalling volume increases. Apart from the frequency of collisions during installation and slab deformation when supporting vehicle loads. Concrete spalling problems also due to inappropriate concrete quality.

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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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Lim, Bryan, and Pei Jun Hong. "Sprayed-On Polymer as Concrete Spall Shield." Solid State Phenomena 136 (February 2008): 145–52. http://dx.doi.org/10.4028/www.scientific.net/ssp.136.145.

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Concrete when subjected to a blast loading from a close-in detonation will experience spalling due to formation of tension waves on the opposite face of the concrete panel. The spalled concrete may be ejected at high velocity causing undesirable effects to occupants. Tests using 1/2kg TNT blocks were conducted on 100mm thick concrete panels to study the effects of spalling and whether the spalled materials can be arrested using a sprayed-on polymeric coating. From the tests, it was observed that without the sprayed-on polymeric coating, extensive spalling occurred. However, with just a 3-4mm thick layer of sprayed-on polymer, the spalled materials were arrested and contained. Numerical models of the reinforced concrete slab were created using Autodyn 2D and the results of the simulation were compared to observations from the tests. There was good correlation between the test results and the simulation results as the size of the crater, both front and back, on the concrete slab were rather similar.

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Han, Cheon Goo, Min Cheol Han, Chan Chun Pei, and Seong Hwan Yang. "Effect of Types and Contents of Polymer Resin on Spalling Prevention of High-Strength Concrete Subjected to Fire." Key Engineering Materials 466 (January 2011): 85–95. http://dx.doi.org/10.4028/www.scientific.net/kem.466.85.

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In this study, the fundamental and spalling properties of high-strength concrete were examined, especially when various types and varying content of polymer resin were added. Two types of polymers were used in this study: ethylene vinyl acetate copolymer (EVA-P) and polyvinyl acetate copolymer (PVA-P) as powders and polyvinyl acetate copolymer (PVA-F) and polypropylene copolymer (PP-F) as fibers. Test results showed that the addition of EVA-P and PVA-F to concrete slightly decreased flowability, whereas the addition of PP-F and PVA-P enhanced the viscosity, leading to a remarkable reduction in flowability. The air content of concrete containing EVA-P, PVA-F, and PP-F showed no significant variation. The addition of PVA-P to concrete also caused a slight reduction in compressive strength, whereas the other additives had insignificant effects. After a fire test, the control concrete and concretes with EVA-P, PVA-P, and PVA-F exhibited severe explosive spalling regardless of the dosages. This was because the polymer does not provide sufficient void networks, which is important for vapor evacuation, which enables the release of steam pressure inside the concrete. However, when more than 0.10% of PP-F was added, spalling was effectively prevented. For the residual compressive strength, higher polymer dosage in the concrete produced better results regardless of the polymer type. The powder-type polymers did not contribute to preventing spalling in concrete subjected to fire. This is due to their geometric shape and high melting point. It is concluded that a high aspect ratio and low melting point is critical during polymer selection to prevent spalling in high-strength concrete.

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Journal articles on the topic 'Spalling of concrete matrix'

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