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Fracture Toughness and Modelling of Concrete Composites and Other Brittle Materials

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Materials Simulation and Design".

Deadline for manuscript submissions: closed (31 October 2022) | Viewed by 33830

Special Issue Editor


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Guest Editor
Department of Structural Engineering, Faculty of Civil Engineering and Architecture, Lublin University of Technology, Nadbystrzycka 40 Str., 20-618 Lublin, Poland
Interests: fracture toughness and fracture processes of concrete composites; concretes with mineral additives; concretes with fly ash addition exposed to various types of loads (mechanical; thermal; corrosion); nanotechnology in concrete; concrete made on ternary and quaternary binders; reinforced concrete structures loaded dynamically

Special Issue Information

Dear Colleagues,

It is my pleasure to invite you to submit a manuscript to the forthcoming Special Issue “Fracture Toughness and Modeling of Concrete Composites and other Brittle Materials” in Materials (Impact Factor 2.972).

Fracture toughness is an extremely important parameter determining the properties of a given material, especially of a construction material. The material constants determined in compressive and tensile tests are not enough because often, materials with high mechanical properties (high strength) have low fracture toughness. In this case, such materials have limited usefulness as structural materials, especially in terms of fatigue loads in a given structure.

Cracks are an evident threat to the structure, as they significantly reduce its strength. The size of cracks formed in construction elements can be presented in the form of a function of operating time or number of load cycles. As time passes, the current strength of the elements changes. After some time of operation, its value decreases to the level at which the construction element is not able to transfer accidental overloads occurring during operation. Such a situation may lead to the destruction of a particular element or even the entire structure, leading to a catastrophe. If failure has not occurred yet, the crack propagates until the value of the structure’s current strength decreases to the level at which the nominal load of the element leads to its destruction. In practice, this means that every construction element of the structure has a period of safe operation, in which the probability of catastrophic failure should be kept as low as possible.

To this end, experimental research and numerical analyses have been conducted for many years to obtain concrete composites with the highest fracture toughness. Recently, material modification of concrete with mineral additives and chemical admixtures, as well as nanomaterials (e.g., nanosilica) has gained special development. More and more advanced techniques are also used to detect and analyze the development of cracks in the material, e.g., the digital image correlation method (DIC), acoustic emission (AE), and computed tomography (CT). The increasingly advanced modeling of fracture processes in composites with brittle matrixes (e.g., using the X-FEM method) allows a more in-depth understanding of fracture processes occurring in the material structure, especially at the interfaces of the composite.

Therefore, it is my pleasure to invite you to submit a manuscript for this Special Issue mainly focused on novel materials that modify the structure of concrete to improve its fracture toughness, and new devices and measuring techniques for analyzing cracks in concrete. Articles on modeling cracks in concrete will also be appreciated, as well as publications related to the assessment of the microstructure of damaged composites.

Moreover, I would like to invite authors of papers which analyze cracking processes in real structures, e.g., historic ones, whose aim is to assess and improve the durability of existing buildings.

The topics of interest include but are not limited to:

  • Linear and nonlinear fracture mechanics in the description of the fracture processes of Concrete composites and concrete structures;
  • Mechanisms of concrete cracking at the macro, micro and nano scale;
  • Cracking of concrete and concrete structures in complex stress conditions;
  • Cracking of concrete and concrete structures as a result of dynamic loads;
  • Improvement of fracture toughness of concrete as a result of using materials modification;
  • Influence of high and low temperatures on fracture processes in concrete;
  • The impact of the environment and corrosive factors on the development of cracks in concrete;
  • Experimental methods in fracture mechanics of concrete composites and other materials;
  • Modeling of fracture processes;
  • The role of contact layers in the process of developing cracks in the composites;
  • The use of nanotechnology to improve the fracture toughness of materials;
  • Forecasting and analysis cracks in existing structures.

Prof. Grzegorz Ludwik Golewski
Guest Editor

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Keywords

  • fracture toughness
  • fracture processes
  • crack
  • concrete composite
  • concrete structures
  • materials with brittle matrixes
  • materials modification
  • microstructure
  • experimental testing
  • modeling

Published Papers (14 papers)

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Research

Jump to: Review

19 pages, 5747 KiB  
Article
Defect Detection and Characterization in Concrete Based on FEM and Ultrasonic Techniques
by Jeongnam Kim, Younho Cho, Jungwon Lee and Young H. Kim
Materials 2022, 15(22), 8160; https://doi.org/10.3390/ma15228160 - 17 Nov 2022
Cited by 2 | Viewed by 1275
Abstract
In order to estimate the crack depth in concrete using time-of-flight, finite element analysis and experiments were performed on non-cracked concrete blocks and 45 mm and 70 mm vertical cracks. As a result of measuring the time-of-flight change by changing the positions of [...] Read more.
In order to estimate the crack depth in concrete using time-of-flight, finite element analysis and experiments were performed on non-cracked concrete blocks and 45 mm and 70 mm vertical cracks. As a result of measuring the time-of-flight change by changing the positions of the transmitter and receiver, it was confirmed that the finite element analysis results agreed with the experimental results, and high accuracy was confirmed by various formulas for calculating the depth of defects using the obtained experimental measurements for comparison. In addition to the verification of the simulation and experimental theory, research was conducted through actual field cases, and methodologies for crack detection and depth evaluation for concrete structures were presented, and furthermore, the expected effects of improving the soundness and safety of structures were shown. Full article
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18 pages, 3510 KiB  
Article
Fracture Performance of Cementitious Composites Based on Quaternary Blended Cements
by Grzegorz Ludwik Golewski
Materials 2022, 15(17), 6023; https://doi.org/10.3390/ma15176023 - 31 Aug 2022
Cited by 71 | Viewed by 2124
Abstract
This study presents test results and in-depth discussion regarding the measurement of the fracture mechanics parameters of new concrete composites based on quaternary blended cements (QBC). A composition of the two most commonly used mineral additives, i.e., fly ash (FA) and silica fume [...] Read more.
This study presents test results and in-depth discussion regarding the measurement of the fracture mechanics parameters of new concrete composites based on quaternary blended cements (QBC). A composition of the two most commonly used mineral additives, i.e., fly ash (FA) and silica fume (SF), in combination with nanosilica (nS), has been proposed as a partial replacement for ordinary Portland cement (OPC) binder. Four series of concrete were made, one of which was the reference concrete (REF) and the remaining three were QBC. During the research, the main mechanical parameters of compressive strength (fcm) and splitting tensile strength (fctm), as well as fracture mechanics parameters and the critical stress intensity factor KIcS, along with critical crack-tip opening displacements (CTODc) were investigated. Based on the tests, it was found that the total addition of siliceous materials, i.e., SF + nS without FA, increases the strength and fracture parameters of concrete by approximately 40%. On the other hand, supplementing the composition of the binder with SF and nS with 5% of FA additive causes an increase in all mechanical parameters by approximately 10%, whereas an increase by another 10% in the FA content in the concrete mix causes a significant decrease in all the analyzed factors by 10%, compared to the composite with the addition of silica modifiers only. Full article
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14 pages, 4796 KiB  
Article
Assessment of Destructive Impact of Different Factors on Concrete Structures Durability
by Janusz R. Krentowski
Materials 2022, 15(1), 225; https://doi.org/10.3390/ma15010225 - 29 Dec 2021
Cited by 10 | Viewed by 1964
Abstract
The durability of concrete structure members is dependent on several factors that should be analyzed at each stage of the construction process. Omitting any of these factors might lead to the augmentation of harmful interactions and, as an effect, to safety hazards and [...] Read more.
The durability of concrete structure members is dependent on several factors that should be analyzed at each stage of the construction process. Omitting any of these factors might lead to the augmentation of harmful interactions and, as an effect, to safety hazards and the degradation of a structure or its parts. The article, based on several years of studies on exploited concrete structures, presents the effects of an incorrect analysis of selected factors resulting in the occurrence of faults significantly influencing the possibility of safe use of the objects. The described cases include, but are not limited to, the consequences of an improper assessment of building conditions after a biogas explosion in a fermentation chamber, the effect of a wood dust explosion, fire temperature and firefighting action on the prestressed girders, the stages of degradation of bearing structures supporting gas tanks exploited in an aggressive environment, and the consequences of omitting the temperature load in relation to the upper surface of a plate covering the fire pond. In each case, methods of restoration of the damaged elements were proposed, and their application to engineering practice was described. The practical aspects of the conducted research and implemented interventions were indicated. Full article
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22 pages, 9096 KiB  
Article
Application of the C-S-H Phase Nucleating Agents to Improve the Performance of Sustainable Concrete Composites Containing Fly Ash for Use in the Precast Concrete Industry
by Grzegorz Ludwik Golewski and Bartosz Szostak
Materials 2021, 14(21), 6514; https://doi.org/10.3390/ma14216514 - 29 Oct 2021
Cited by 65 | Viewed by 1889
Abstract
Siliceous fly ash (FA) is the main additive to currently produced concretes. The utilization of this industrial waste carries an evident pro-ecological factor. In addition, such actions have a positive effect on the structure and mechanical parameters of mature concrete. Unfortunately, the problem [...] Read more.
Siliceous fly ash (FA) is the main additive to currently produced concretes. The utilization of this industrial waste carries an evident pro-ecological factor. In addition, such actions have a positive effect on the structure and mechanical parameters of mature concrete. Unfortunately, the problem of using FA as a Portland cement replacement is that it significantly reduces the performance of concretes in the early stages of their curing. This limits the possibility of using this type of concrete, e.g., in prefabrication, where it is required to obtain high-strength composites after short periods of curing. In order to minimize these negative effects, this research was undertaken to increase the early strength of concretes with FA through the application of a specifically formulated chemical nano-admixture (NA) in the form of seeds of the C-S-H phase. The NA was used to accelerate the strength growth in concretes. Therefore, this paper presents results of tests of modified concretes both with the addition of FA and with innovative NA. The analyses were carried out based on the results of the macroscopic and microstructural tests in five time periods, i.e., after 4, 8, 12, 24 and 72 h. The results of tests carried out with the use of NA clearly indicate the possibility of using FA in a wide range of management areas in sustainable concrete prefabrication. Full article
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21 pages, 10163 KiB  
Article
Advanced Evaluation of the Freeze–Thaw Damage of Concrete Based on the Fracture Tests
by Barbara Kucharczyková, Hana Šimonová, Dalibor Kocáb and Libor Topolář
Materials 2021, 14(21), 6378; https://doi.org/10.3390/ma14216378 - 25 Oct 2021
Cited by 3 | Viewed by 1492
Abstract
This paper presents the results of an experimental program aimed at the assessment of the freeze–thaw (F–T) resistance of concrete based on the evaluation of fracture tests accompanied by acoustic emission measurements. Two concretes of similar mechanical characteristics were manufactured for the experiment. [...] Read more.
This paper presents the results of an experimental program aimed at the assessment of the freeze–thaw (F–T) resistance of concrete based on the evaluation of fracture tests accompanied by acoustic emission measurements. Two concretes of similar mechanical characteristics were manufactured for the experiment. The main difference between the C1 and C2 concrete was in the total number of air voids and in the A300 parameter, where both parameters were higher for C1 by about 35% and 52%, respectively. The evaluation of the fracture characteristics was performed on the basis of experimentally recorded load–deflection and load–crack mouth opening displacement diagrams using two different approaches: linear fracture mechanics completed with the effective crack model and the double-K model. The results show that both approaches gave similar results, especially if the nonlinear behavior before the peak load was considered. According to the results, it can be stated that continuous AE measurement is beneficial for the assessment of the extent of concrete deterioration, and it suitably supplements the fracture test evaluation. A comparison of the results of fracture tests with the resonance method and splitting tensile strength test shows that all testing methods led to the same conclusion, i.e., the C1 concrete was more F–T-resistant than C2. However, the fracture test evaluation provided more detailed information about the internal structure deterioration due to the F–T exposure. Full article
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14 pages, 3943 KiB  
Article
Evaluation of Mode II Fracture Toughness of Hybrid Fibrous Geopolymer Composites
by Sallal R. Abid, Gunasekaran Murali, Mugahed Amran, Nikolai Vatin, Roman Fediuk and Maria Karelina
Materials 2021, 14(2), 349; https://doi.org/10.3390/ma14020349 - 12 Jan 2021
Cited by 57 | Viewed by 2206
Abstract
This research aims to examine the fracture toughness of hybrid fibrous geopolymer composites under mode II. For this purpose, eight geopolymer mixtures were cast and tested to evaluate the influence of steel and synthetic fiber hybridization on mode II fracture response. The first [...] Read more.
This research aims to examine the fracture toughness of hybrid fibrous geopolymer composites under mode II. For this purpose, eight geopolymer mixtures were cast and tested to evaluate the influence of steel and synthetic fiber hybridization on mode II fracture response. The first mixture was plain and was kept as a reference, while steel, polypropylene and glass fibers were used in the rest seven mixtures. The first three of which were mono-reinforced with one of the three fibers, while the rest of the four were hybrids reinforced with combinations of steel and synthetic fibers. The Brazilian center notched disc and the double notched cube test configurations were used to evaluate the mode II fracture toughness of the eight mixtures. The results of the tests showed that steel fibers played the vital role in enhancing the fracture toughness, where the mixtures S1.6 and S1.3G0.3 showed the best performance. The results also showed that increasing the notch depth decreased the fracture toughness with an approximate linear decrement fashion. It was found that the use of double-notched cubes resulted in much higher fracture toughness than the Brazilian notched discs, where the ratio of normalized fracture toughness of the disc specimens to cube specimens was approximately 0.37 to 0.47. This is attributed to the concentration of stresses along one defined path in the disc specimens compared to the multi-path stresses in the cube specimens. In addition, the accompanied tensile stresses in the disc specimens may lead to a mode I fracture before the designed mode II fracture. Full article
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21 pages, 10605 KiB  
Article
Studies of Fracture Toughness in Concretes Containing Fly Ash and Silica Fume in the First 28 Days of Curing
by Grzegorz Ludwik Golewski and Damian Marek Gil
Materials 2021, 14(2), 319; https://doi.org/10.3390/ma14020319 - 9 Jan 2021
Cited by 85 | Viewed by 2951
Abstract
This paper presents the results of the fracture toughness of concretes containing two mineral additives. During the tests, the method of loading the specimens according to Mode I fracture was used. The research included an evaluation of mechanical parameters of concrete containing noncondensed [...] Read more.
This paper presents the results of the fracture toughness of concretes containing two mineral additives. During the tests, the method of loading the specimens according to Mode I fracture was used. The research included an evaluation of mechanical parameters of concrete containing noncondensed silica fume (SF) in an amount of 10% and siliceous fly ash (FA) in the following amounts: 0%, 10% and 20%. The experiments were carried out on mature specimens, i.e., after 28 days of curing and specimens at an early age, i.e., after 3 and 7 days of curing. In the course of experiments, the effect of adding SF to the value of the critical stress intensity factor—KIcS in FA concretes in different periods of curing were evaluated. In addition, the basic strength parameters of concrete composites, i.e., compressive strength—fcm and splitting tensile strength—fctm, were measured. A novelty in the presented research is the evaluation of the fracture toughness of concretes with two mineral additives, assessed at an early age. During the tests, the structures of all composites and the nature of macroscopic crack propagation were also assessed. A modern and useful digital image correlation (DIC) technique was used to assess macroscopic cracks. Based on the conducted research, it was found the application of SF to FA concretes contributes to a significant increase in the fracture toughness of these materials at an early age. Moreover, on the basis of the obtained test results, it was found that the values of the critical stress intensity factor of analyzed concretes were convergent qualitatively with their strength parameters. It also has been demonstrated that in the first 28 days of concrete curing, the preferred solution is to replace cement with SF in the amount of 10% or to use a cement binder substitution with a combination of additives in proportions 10% SF + 10% FA. On the other hand, the composition of mineral additives in proportions 10% SF + 20% FA has a negative effect on the fracture mechanics parameters of concretes at an early age. Based on the analysis of the results of microstructural tests and the evaluation of the propagation of macroscopic cracks, it was established that along with the substitution of the cement binder with the combination of mineral additives, the composition of the cement matrix in these composites changes, which implies a different, i.e., quasi-plastic, behavior in the process of damage and destruction of the material. Full article
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19 pages, 2857 KiB  
Article
The Effect of Steel and Polypropylene Fibers on the Properties of Horizontally Formed Concrete
by Adrian Chajec and Łukasz Sadowski
Materials 2020, 13(24), 5827; https://doi.org/10.3390/ma13245827 - 21 Dec 2020
Cited by 21 | Viewed by 2451
Abstract
The article presents a comparative analysis of the impact of the addition of steel and polypropylene fibers on the properties of the concrete mixes and hardened concrete used in the concrete floor industry. The behavior of concrete intended for floors is different from [...] Read more.
The article presents a comparative analysis of the impact of the addition of steel and polypropylene fibers on the properties of the concrete mixes and hardened concrete used in the concrete floor industry. The behavior of concrete intended for floors is different from conventional structural concrete because it is formed horizontally; until now, the effect of steel and polypropylene fibers on the properties of concrete formed horizontally has not yet been fully understood. Therefore, the aim of this article is to examine this issue and compare the behavior of concrete modified with steel and polypropylene fibers in concrete that is formed horizontally. The following properties of fresh concrete mixes were analyzed: consistency, the content of air-voids, and bulk density. Consequently, the following properties of hardened concrete were analyzed: compressive strength, bending tensile strength, and brittleness. It was confirmed that steel and polypropylene fibers have a different type of effect on the properties of fresh concrete mixes and hardened concrete. Finally, a combined economic and mechanical analysis was performed. Full article
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24 pages, 9148 KiB  
Article
Changes in the Fracture Toughness under Mode II Loading of Low Calcium Fly Ash (LCFA) Concrete Depending on Ages
by Grzegorz Ludwik Golewski
Materials 2020, 13(22), 5241; https://doi.org/10.3390/ma13225241 - 19 Nov 2020
Cited by 56 | Viewed by 2290
Abstract
This study investigated the influence of the curing time on the fracture toughness of concrete produced with different content of low calcium fly ash (LCFA). During the study, the amounts of 20% and 30% of pozzolanic additive were used. In order to observe [...] Read more.
This study investigated the influence of the curing time on the fracture toughness of concrete produced with different content of low calcium fly ash (LCFA). During the study, the amounts of 20% and 30% of pozzolanic additive were used. In order to observe the effect of the applied pozzolanic additive on the analyzed concrete properties, the obtained results were compared with the values obtained for the reference concrete. Compressive strength—fcm and fracture toughness, by using mode II loading—KIIc (shearing), were determined between the 3rd and 365th days of curing. In the course of experiments, changes in the development of cracks in individual series of concrete were also analyzed. In addition, the microstructures of all composites and the nature of macroscopic crack propagation in mature concretes were assessed. It was observed that the greatest increase in fracture toughness at shear was in the case of reference concrete during the first 28 days, whereas, in the case of concretes containing LCFA, in the period of time above 4 weeks. Furthermore, concrete without the LCFA additives were characterized by a brittle fracture. In contrast to it, concretes with LCFA additives are mainly characterized by a quasi-plastic process of failure. Moreover, most of the samples showed a typical pattern of the destruction that occurs as a result of shearing. The presented test results may be helpful in selecting the composition of concrete mixtures containing LCFA to be used in concrete and reinforced concrete structures subjected to shear loads. Full article
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16 pages, 2617 KiB  
Article
Influence of Fly Ash Additive on the Properties of Concrete with Slag Cement
by Anna Szcześniak, Jacek Zychowicz and Adam Stolarski
Materials 2020, 13(15), 3265; https://doi.org/10.3390/ma13153265 - 23 Jul 2020
Cited by 35 | Viewed by 2706
Abstract
This paper presents research on the impact of fly ash addition on selected physical and mechanical parameters of concrete made with slag cement. Experimental tests were carried out to measure the migration of chloride ions in concrete, the tightness of concrete exposed to [...] Read more.
This paper presents research on the impact of fly ash addition on selected physical and mechanical parameters of concrete made with slag cement. Experimental tests were carried out to measure the migration of chloride ions in concrete, the tightness of concrete exposed to water under pressure, and the compressive strength and tensile strength of concrete during splitting. Six series of concrete mixes made with CEM IIIA 42.5 and 32.5 cement were tested. The base concrete mix was modified by adding fly ash as a partial cement substitute in the amounts of 25% and 33%. A comparative analysis of the obtained results indicates a significant improvement in tightness, especially in concrete based on CEM IIIA 32.5 cement and resistance to chloride ion penetration for the concretes containing fly ash additive. In the concretes containing fly ash additive, a slower rate of initial strength increase and high strength over a long period of maturation are shown. In accordance with the presented research results, it is suggested that changes to the European standardization system be considered, to allow the use of fly ash additive in concrete made with CEM IIIA 42.5 or 32.5 cement classes. Such a solution is not currently acceptable in standards in some European Countries. Full article
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12 pages, 3251 KiB  
Article
Resistance of External Thermal Insulation Composite Systems with Rendering (ETICS) to Hail
by Barbara Francke and Renata Zamorowska
Materials 2020, 13(11), 2452; https://doi.org/10.3390/ma13112452 - 28 May 2020
Cited by 10 | Viewed by 2244
Abstract
This paper analyzes the resistance to hail of external thermal insulation composite systems (ETICS), i.e., external thermal insulation of foamed polystyrene with the same finishing coat and various reinforcing mesh and base coats used to make the reinforced layer. The manuscript presents our [...] Read more.
This paper analyzes the resistance to hail of external thermal insulation composite systems (ETICS), i.e., external thermal insulation of foamed polystyrene with the same finishing coat and various reinforcing mesh and base coats used to make the reinforced layer. The manuscript presents our own new method for assessing ETICS resistance to hail and test results obtained according to this method. The basic premise of the presented new research methodology is evaluation of the thermal insulation system surface damage and fracture toughness, in the function of hit velocity with a polyamide ball with a standardized diameter and weight. The results of hail resistance tests were compared with the values of hard body impact resistance obtained in the tests done according to ETAG 004. Results obtained by the new method help to evaluate precisely the resistance of thermal insulation sets to damage as a result of impact of heavy objects of permanent shape, with greater accuracy than the hard body impact test. They also confirmed that thermal insulation sets with dispersion adhesive in the reinforcement demonstrate greater resistance to damage as a result of hail impact than the sets with cement-based adhesives and that weight of the reinforcing mesh used in the system is not significant to affect the hail resistance. Full article
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16 pages, 4762 KiB  
Article
Numerical Simulation on Size Effect of Fracture Toughness of Concrete Based on Mesomechanics
by Juan Wang, Qianqian Wu, Junfeng Guan, Peng Zhang, Hongyuan Fang and Shaowei Hu
Materials 2020, 13(6), 1370; https://doi.org/10.3390/ma13061370 - 18 Mar 2020
Cited by 14 | Viewed by 2668
Abstract
The fracture performance of concrete is size-dependent within a certain size range. A four-phase composite material numerical model of mesofracture considering a mortar matrix, coarse aggregates, an interfacial transition zone (ITZ) at the meso level and the initial defects of concrete was established. [...] Read more.
The fracture performance of concrete is size-dependent within a certain size range. A four-phase composite material numerical model of mesofracture considering a mortar matrix, coarse aggregates, an interfacial transition zone (ITZ) at the meso level and the initial defects of concrete was established. The initial defects were assumed to be distributed randomly in the ITZ of concrete. The numerical model of concrete mesofracture was established to simulate the fracture process of wedge splitting (WS) concrete specimens with widths of 200–2000 mm and three-point bending (3-p-b) concrete specimens with heights of 200–800 mm. The fracture process of concrete was simulated, and the peak load (Pmax) of concrete was predicted using the numerical model. Based on the simulating results, the influence of specimen size of WS and 3-p-b tests on the fracture parameters was analyzed. It was demonstrated that when the specimen size was large enough, the fracture toughness (KIC) value obtained by the linear elastic fracture mechanics formula was independent of the specimen size. Meanwhile, the improved boundary effect model (BEM) was employed to study the tensile strength (ft) and fracture toughness of concrete using the mesofracture numerical model. A discrete value of β = 1.0–1.4 was a sufficient approximation to determine the ft and KIC values of concrete. Full article
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Review

Jump to: Research

44 pages, 68441 KiB  
Review
Effect of Short Fiber Reinforcements on Fracture Performance of Cement-Based Materials: A Systematic Review Approach
by Waqas Ahmad, Mehran Khan and Piotr Smarzewski
Materials 2021, 14(7), 1745; https://doi.org/10.3390/ma14071745 - 1 Apr 2021
Cited by 62 | Viewed by 3818
Abstract
Fracture characteristics were used to effectively evaluate the performance of fiber-reinforced cementitious composites. The fracture parameters provided the basis for crack stability analysis, service performance, safety evaluation, and protection. Much research has been carried out in the proposed study field over the previous [...] Read more.
Fracture characteristics were used to effectively evaluate the performance of fiber-reinforced cementitious composites. The fracture parameters provided the basis for crack stability analysis, service performance, safety evaluation, and protection. Much research has been carried out in the proposed study field over the previous two decades. Therefore, it was required to analyze the research trend from the available bibliometric data. In this study, the scientometric analysis and science mapping techniques were performed along with a comprehensive discussion to identify the relevant publication field, highly used keywords, most active authors, most cited articles, and regions with largest impact on the field of fracture properties of cement-based materials (CBMs). Furthermore, the characteristic of various fibers such as steel, polymeric, inorganic, and carbon fibers are discussed, and the factors affecting the fracture properties of fiber-reinforced CBMs (FRCBMs) are reviewed. In addition, future gaps are identified. The graphical representation based on the scientometric review could be helpful for research scholars from different countries in developing research cooperation, creating joint ventures, and exchanging innovative technologies and ideas. Full article
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27 pages, 2036 KiB  
Review
Fracture Models and Effect of Fibers on Fracture Properties of Cementitious Composites—A Review
by Peng Zhang, Yonghui Yang, Juan Wang, Meiju Jiao and Yifeng Ling
Materials 2020, 13(23), 5495; https://doi.org/10.3390/ma13235495 - 2 Dec 2020
Cited by 19 | Viewed by 2413
Abstract
Cementitious composites have good ductility and pseudo-crack control. However, in practical applications of these composites, the external load and environmental erosion eventually form a large crack in the matrix, resulting in matrix fracture. The fracture of cementitious composite materials causes not only structural [...] Read more.
Cementitious composites have good ductility and pseudo-crack control. However, in practical applications of these composites, the external load and environmental erosion eventually form a large crack in the matrix, resulting in matrix fracture. The fracture of cementitious composite materials causes not only structural insufficiency, but also economic losses associated with the maintenance and reinforcement of cementitious composite components. Therefore, it is necessary to study the fracture properties of cementitious composites for preventing the fracture of the matrix. In this paper, a multi-crack cracking model, fictitious crack model, crack band model, pseudo-strain hardening model, and double-K fracture model for cementitious composites are presented, and their advantages and disadvantages are analyzed. The multi-crack cracking model can determine the optimal mixing amount of fibers in the matrix. The fictitious crack model and crack band model are stress softening models describing the cohesion in the fracture process area. The pseudo-strain hardening model is mainly applied to ductile materials. The double-K fracture model mainly describes the fracture process of concrete. Additionally, the effects of polyvinyl alcohol (PVA) fibers and steel fibers (SFs) on the fracture properties of the matrix are analyzed. The fracture properties of cementitious composite can be greatly improved by adding 1.5–2% PVA fiber or 4% steel fiber (SF). The fracture property of cementitious composite can also be improved by adding 1.5% steel fiber and 1% PVA fiber. However, there are many problems to be solved for the application of cementitious composites in actual engineering. Therefore, further research is needed to solve the fracture problems frequently encountered in engineering. Full article
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