Geopolymer recycled brick aggregate concrete (GRC) can reduce CO2 emission and effectively utilize construction waste, which is a new type of green environmental friendly material. To study its basic compressive performance and stress-strain relationship, the cubes and prisms of geopolymer recycled brick aggregate concrete (GRC) and ordinary recycled brick aggregate concrete (ORC) under five recycled brick aggregate (RBA) replacement ratios (0, 25%, 50%, 75% and 100%) were tested compressively. The failure mode, working performance, compressive strength, elastic modulus, Poisson's ratio and other indexes as well as the full stress-strain curves were obtained. The test results show that with the increase of RBA replacement ratio, the compressive strength and modulus of elasticity of GRC and ORC decrease, and the slump, strain corresponding to peak stress, transverse deformation coefficient and Poisson's ratio increase. Compared with ORC, under the same water-to-binder ratio, GRC exhibits 29% to 52% smaller elastic modulus, more than 30% reduction in slump, close Poisson's ratio and steeper decline branch of compressive stress-strain curve. Moreover, the RBA replacement ratio has a greater effect on GRC. Based on the uniaxial compressive model of ordinary concrete, the compressive constitutive models suitable for GRC and ORC are proposed.
{"title":"Compressive performance and stress-strain relationship of geopolymer recycled brick aggregate concrete","authors":"Y. Zheng, Lili Zheng, Yu-qing Wang","doi":"10.1680/jmacr.22.00269","DOIUrl":"https://doi.org/10.1680/jmacr.22.00269","url":null,"abstract":"Geopolymer recycled brick aggregate concrete (GRC) can reduce CO2 emission and effectively utilize construction waste, which is a new type of green environmental friendly material. To study its basic compressive performance and stress-strain relationship, the cubes and prisms of geopolymer recycled brick aggregate concrete (GRC) and ordinary recycled brick aggregate concrete (ORC) under five recycled brick aggregate (RBA) replacement ratios (0, 25%, 50%, 75% and 100%) were tested compressively. The failure mode, working performance, compressive strength, elastic modulus, Poisson's ratio and other indexes as well as the full stress-strain curves were obtained. The test results show that with the increase of RBA replacement ratio, the compressive strength and modulus of elasticity of GRC and ORC decrease, and the slump, strain corresponding to peak stress, transverse deformation coefficient and Poisson's ratio increase. Compared with ORC, under the same water-to-binder ratio, GRC exhibits 29% to 52% smaller elastic modulus, more than 30% reduction in slump, close Poisson's ratio and steeper decline branch of compressive stress-strain curve. Moreover, the RBA replacement ratio has a greater effect on GRC. Based on the uniaxial compressive model of ordinary concrete, the compressive constitutive models suitable for GRC and ORC are proposed.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41729490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Autogenous curing, also known as internal curing (IC), has revolutionized the way high-performance and high-strength concrete (HPC and HSC) are cured. It has improved concrete's service life by lowering early-age cracking and enhancing its durability. However, normal-strength concrete (NSC) is still the most commonly used type of concrete in the industry, and it is typically cured using conventional methods with poor oversight. As a result, researchers are looking at ways to reproduce the positive results observed in internally cured HSC/HPC. Studies show that IC is feasible in NSC despite the higher permeability, which results in the loss of internal curing water. However, no comprehensive research has attempted to assess how the type, size, and amount of internal curing agents affect the properties of NSC. Thus, this study aims to optimize the IC parameters for the autonomous curing of NSC. The outcomes of this study support the notion that IC is possible in high w/c ratio concrete and that, compared to lightweight aggregates (LWA), superabsorbent polymers (SAP) significantly impact the durability properties of NSC. Moreover, varying the size of the IC agent (LWA) had little effect on NSC properties, and increasing the amount of IC water content considerably improved the NSC's durability properties.
{"title":"Optimizing internal curing parameters for autonomous curing of normal-strength concrete","authors":"Tesfaalem Gereziher Atsbha, S. Zhutovsky","doi":"10.1680/jmacr.22.00254","DOIUrl":"https://doi.org/10.1680/jmacr.22.00254","url":null,"abstract":"Autogenous curing, also known as internal curing (IC), has revolutionized the way high-performance and high-strength concrete (HPC and HSC) are cured. It has improved concrete's service life by lowering early-age cracking and enhancing its durability. However, normal-strength concrete (NSC) is still the most commonly used type of concrete in the industry, and it is typically cured using conventional methods with poor oversight. As a result, researchers are looking at ways to reproduce the positive results observed in internally cured HSC/HPC. Studies show that IC is feasible in NSC despite the higher permeability, which results in the loss of internal curing water. However, no comprehensive research has attempted to assess how the type, size, and amount of internal curing agents affect the properties of NSC. Thus, this study aims to optimize the IC parameters for the autonomous curing of NSC. The outcomes of this study support the notion that IC is possible in high w/c ratio concrete and that, compared to lightweight aggregates (LWA), superabsorbent polymers (SAP) significantly impact the durability properties of NSC. Moreover, varying the size of the IC agent (LWA) had little effect on NSC properties, and increasing the amount of IC water content considerably improved the NSC's durability properties.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48326223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work experimentally evaluates the friction shear behavior of Electric Arc Furnace (EAF) concrete, compared to its reference counterpart made with natural aggregates only. For this scope, two concrete mixes were casted, both containing a blended cement with 30% of fly ash to improve their sustainability. For each mix, other than analyzing the main mechanical properties (compressive, tensile strength and elastic modulus), push-off specimens were tested to obtain the shear strength, failure modes, stress-slip and stress-crack opening curves. The results obtained here clearly identify an enhancement of the shear strength τ of EAF concrete compared to the reference, even though the relation between τ and concrete tensile strength fct is similar between the two concretes. Results are also compared with ones in literature, dealing with ordinary and recycled aggregate concrete (RAC). Further, existing models from both designing codes and literature were applied to the experimental results, obtaining conservative predictions in all cases. The safety margin for the EAF concrete was found to be higher than for the reference concrete.
{"title":"Shear transfer in fly ash-concrete with electric arc furnace aggregates","authors":"F. Faleschini, Daniel Trento, V. Lopez, M. Zanini","doi":"10.1680/jmacr.22.00280","DOIUrl":"https://doi.org/10.1680/jmacr.22.00280","url":null,"abstract":"This work experimentally evaluates the friction shear behavior of Electric Arc Furnace (EAF) concrete, compared to its reference counterpart made with natural aggregates only. For this scope, two concrete mixes were casted, both containing a blended cement with 30% of fly ash to improve their sustainability. For each mix, other than analyzing the main mechanical properties (compressive, tensile strength and elastic modulus), push-off specimens were tested to obtain the shear strength, failure modes, stress-slip and stress-crack opening curves. The results obtained here clearly identify an enhancement of the shear strength τ of EAF concrete compared to the reference, even though the relation between τ and concrete tensile strength fct is similar between the two concretes. Results are also compared with ones in literature, dealing with ordinary and recycled aggregate concrete (RAC). Further, existing models from both designing codes and literature were applied to the experimental results, obtaining conservative predictions in all cases. The safety margin for the EAF concrete was found to be higher than for the reference concrete.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45029550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The influence of the hardening accelerator and steel fiber on the concrete adhesion strength for the repair of rigid highway and airfield pavements has been investigated. The concretes were mixed based on the CEM II/A-S 42.5 and included MasterGlenium SKY 608 superplasticizer. Experiment with two variable concrete composition factors was carried out. The amount of steel fiber varied from 0 to 100 kg/m3, the amount of Sika Rapid hardening accelerator varied from 0 to 9.6 kg/m3. It was found that modified repair concretes have a sufficiently high adhesion strength to "old" concrete, from 2.30 MPa when tested by the pull-off method and from 2.05 MPa when tested by the flexural strength test method. Fiber-reinforcement increases the adhesion strength of repair concrete by 7-15% due to reducing of shrinkage during hardening. Treating the contact surface of "old" concrete with a primer additionally increases adhesion strength by 6-10%. The maximum adhesion strength of fiber-reinforced concrete to the base reaches 3 MPa. Due to the high early and design strength, modified steel fiber-reinforced concrete provides the possibility of quick resumption of traffic while ensuring the integrity of the road structure due to the joint work of the repair material with the old concrete repair area.
{"title":"Influence of fibers and hardening accelerator on the concrete for rigid pavements","authors":"Ž. Kos, S. Kroviakov, V. Kryzhanovskyi, A. Crnoja","doi":"10.1680/jmacr.22.00181","DOIUrl":"https://doi.org/10.1680/jmacr.22.00181","url":null,"abstract":"The influence of the hardening accelerator and steel fiber on the concrete adhesion strength for the repair of rigid highway and airfield pavements has been investigated. The concretes were mixed based on the CEM II/A-S 42.5 and included MasterGlenium SKY 608 superplasticizer. Experiment with two variable concrete composition factors was carried out. The amount of steel fiber varied from 0 to 100 kg/m3, the amount of Sika Rapid hardening accelerator varied from 0 to 9.6 kg/m3. It was found that modified repair concretes have a sufficiently high adhesion strength to \"old\" concrete, from 2.30 MPa when tested by the pull-off method and from 2.05 MPa when tested by the flexural strength test method. Fiber-reinforcement increases the adhesion strength of repair concrete by 7-15% due to reducing of shrinkage during hardening. Treating the contact surface of \"old\" concrete with a primer additionally increases adhesion strength by 6-10%. The maximum adhesion strength of fiber-reinforced concrete to the base reaches 3 MPa. Due to the high early and design strength, modified steel fiber-reinforced concrete provides the possibility of quick resumption of traffic while ensuring the integrity of the road structure due to the joint work of the repair material with the old concrete repair area.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46905112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Split Hopkinson pressure bar (SHPB) is commonly used to characterize materials under high strain rates. However, conventional SHPB tests on brittle materials has encountered several experimental challenges for the high strain rate loading. In relatively brittle materials like concrete, the deformation of the specimen is very small when subjected to the impact loading; hence, it is very difficult to obtain the prerequisites of valid SHPB tests like dynamic equilibrium and constant strain rate in the specimen. To overcome these issues, the current study presents the importance of the pulse shaper approach in SHPB application for dynamic characterization of concrete material. The pulse shaper serves as a function of increasing the loading duration of the incident pulse. An incident pulse with a longer loading duration is a preferred loading pulse for achieving dynamic stress equilibrium in the specimen. Selection of appropriate dimension of pulse shaper assists in facilitating dynamic stress equilibrium and constant strain rate in the specimen. In the present experimental study, copper pulse shapers are used for evaluation of concrete under high strain rate loading using an SHPB setup. Parameters such as the effect of dimensions (diameter and thickness) of pulse shapers on the loading pulses, dynamic equilibrium, constant strain rate, and material responses are studied. Experimental results revealed the prediction of suitable pulse shapers for 50-200 /sec strain rates. In addition, numerical simulation is also performed, and results are validated with the experimental data.
{"title":"Experimental and numerical studies on pulse shaping techniques used in SHPB for testing concrete material","authors":"Kavita Ganorkar, M. Goel, T. Chakraborty","doi":"10.1680/jmacr.22.00212","DOIUrl":"https://doi.org/10.1680/jmacr.22.00212","url":null,"abstract":"Split Hopkinson pressure bar (SHPB) is commonly used to characterize materials under high strain rates. However, conventional SHPB tests on brittle materials has encountered several experimental challenges for the high strain rate loading. In relatively brittle materials like concrete, the deformation of the specimen is very small when subjected to the impact loading; hence, it is very difficult to obtain the prerequisites of valid SHPB tests like dynamic equilibrium and constant strain rate in the specimen. To overcome these issues, the current study presents the importance of the pulse shaper approach in SHPB application for dynamic characterization of concrete material. The pulse shaper serves as a function of increasing the loading duration of the incident pulse. An incident pulse with a longer loading duration is a preferred loading pulse for achieving dynamic stress equilibrium in the specimen. Selection of appropriate dimension of pulse shaper assists in facilitating dynamic stress equilibrium and constant strain rate in the specimen. In the present experimental study, copper pulse shapers are used for evaluation of concrete under high strain rate loading using an SHPB setup. Parameters such as the effect of dimensions (diameter and thickness) of pulse shapers on the loading pulses, dynamic equilibrium, constant strain rate, and material responses are studied. Experimental results revealed the prediction of suitable pulse shapers for 50-200 /sec strain rates. In addition, numerical simulation is also performed, and results are validated with the experimental data.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47316396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper investigates the dissolution rates of alkali-activated fly ash and alkali-activated slag in hydrochloric acid(HCl) with various pH values. XRF, XRD, and FTIR were used to analyze the HCl-insoluble matter of alkali-activated fly ash and alkali-activated slag. The geopolymerization reaction degree of alkali-activated fly ash/slag can be determined based on the content of HCl-insoluble matter. The acid dissolution tests of alkali-activated fly ash/slag show that adding slag increases the geopolymerization degree of fly ash in most cases. With a certain slag content, the reaction degree of fly ash decreases with the increase of activator modulus and increases with the liquid/solid ratio. The increase of the activator concentration has a more pronounced effect when the slag content is low. At low activator concentration, the reaction degree of fly ash increases with the increase of slag content. The slag content corresponding to the highest reaction degree of fly ash is gradually reduced with the increased activator concentration.
{"title":"Analysis of reaction degree and factors of alkali-activated fly ash/slag","authors":"Bowen Wang, Yang Liu, Dong Luo, Yiwei Yang, Dunwen Huang, Hui Peng","doi":"10.1680/jmacr.22.00170","DOIUrl":"https://doi.org/10.1680/jmacr.22.00170","url":null,"abstract":"This paper investigates the dissolution rates of alkali-activated fly ash and alkali-activated slag in hydrochloric acid(HCl) with various pH values. XRF, XRD, and FTIR were used to analyze the HCl-insoluble matter of alkali-activated fly ash and alkali-activated slag. The geopolymerization reaction degree of alkali-activated fly ash/slag can be determined based on the content of HCl-insoluble matter. The acid dissolution tests of alkali-activated fly ash/slag show that adding slag increases the geopolymerization degree of fly ash in most cases. With a certain slag content, the reaction degree of fly ash decreases with the increase of activator modulus and increases with the liquid/solid ratio. The increase of the activator concentration has a more pronounced effect when the slag content is low. At low activator concentration, the reaction degree of fly ash increases with the increase of slag content. The slag content corresponding to the highest reaction degree of fly ash is gradually reduced with the increased activator concentration.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43067281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The bond behavior between fiber-reinforced polymer (FRP) composites and concrete is a complex problem that is influenced by material properties, joint geometric configuration and the surrounding environment. The three fundamental bond-performance indicators of concern are interfacial fracture energy, bond-strength and debonding strain. This paper introduces a new semi-empirical model for predicting interfacial fracture energy (Gf) between externally bonded FRP and intact concrete in terms of the most influential material and geometric parameters; namely, concrete's compressive strength and maximum aggregate size, stiffness of FRP composites and bond width and length of FRP composites relative to the dimensions of the concrete member. The prediction of (Gf) helped generate accurate predictions for the other two bond-performance indicators. The present model was developed using non-linear regression analysis before validation using almost a one-third of the total database consisting of 425 points, collected from credible publications. The accuracy of the present model of (Gf) outperformed those of well-known literature ones. The excellent agreement in trend behavior of the present model with those reported in related literature works postulated further the model's validity. The estimation of debonding strain and bond-strength in terms of fracture energy demonstrated superior accuracy over those provided by different relevant literature models.
{"title":"Semi-empirical models for predicting mode-II bond indicators between FRP and concrete","authors":"Nasser Al-Huthaifi, R. Haddad","doi":"10.1680/jmacr.22.00290","DOIUrl":"https://doi.org/10.1680/jmacr.22.00290","url":null,"abstract":"The bond behavior between fiber-reinforced polymer (FRP) composites and concrete is a complex problem that is influenced by material properties, joint geometric configuration and the surrounding environment. The three fundamental bond-performance indicators of concern are interfacial fracture energy, bond-strength and debonding strain. This paper introduces a new semi-empirical model for predicting interfacial fracture energy (Gf) between externally bonded FRP and intact concrete in terms of the most influential material and geometric parameters; namely, concrete's compressive strength and maximum aggregate size, stiffness of FRP composites and bond width and length of FRP composites relative to the dimensions of the concrete member. The prediction of (Gf) helped generate accurate predictions for the other two bond-performance indicators. The present model was developed using non-linear regression analysis before validation using almost a one-third of the total database consisting of 425 points, collected from credible publications. The accuracy of the present model of (Gf) outperformed those of well-known literature ones. The excellent agreement in trend behavior of the present model with those reported in related literature works postulated further the model's validity. The estimation of debonding strain and bond-strength in terms of fracture energy demonstrated superior accuracy over those provided by different relevant literature models.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43078540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The beam–column joint (BCJ) is a critical region in a framed structure because during such events as earthquakes it is susceptible to earlier failure than adjacent members, leading to shear failure, and will endanger building users if not designed properly. BCJs designed using preseismic code provisions follow the non-ductile approach and might not resist postelastic rotation without enduring greater damage. Retrofitting techniques offer great opportunities for strengthening damaged BCJs. In this study, the effectiveness of a novel retrofitting scheme based on carbon fibre reinforced polymer (CFRP) confined ultrahigh-performance fibre-reinforced concrete (UHPFRC) in rehabilitating initially damaged BCJ specimens was assessed. Three retrofitting schemes using UHPFRC with and without confinement are proposed: (1) in situ casting of 25 mm thick UHPFRC jackets; (2) in situ casting of steel wire mesh-confined UHPFRC and (3) in situ casting of CFRP-confined UHPFRC. The confining action was achieved by sandwiching wire or CFRP mesh between two layers of UHPFRC. The results of this study indicate that BCJ specimens retrofitted with confined UHPFRC had improved overall seismic response, compared with specimens retrofitted only with UHPFRC. Further, the wire mesh-based retrofitting scheme proved to be more efficient than the CFRP mesh-based scheme.
{"title":"Confined ultrahigh-performance fibre-reinforced concrete in retrofitted beam–column joint: experimental study","authors":"Satendra Saharan, Gurbir Kaur, P. Bansal","doi":"10.1680/jmacr.21.00204","DOIUrl":"https://doi.org/10.1680/jmacr.21.00204","url":null,"abstract":"The beam–column joint (BCJ) is a critical region in a framed structure because during such events as earthquakes it is susceptible to earlier failure than adjacent members, leading to shear failure, and will endanger building users if not designed properly. BCJs designed using preseismic code provisions follow the non-ductile approach and might not resist postelastic rotation without enduring greater damage. Retrofitting techniques offer great opportunities for strengthening damaged BCJs. In this study, the effectiveness of a novel retrofitting scheme based on carbon fibre reinforced polymer (CFRP) confined ultrahigh-performance fibre-reinforced concrete (UHPFRC) in rehabilitating initially damaged BCJ specimens was assessed. Three retrofitting schemes using UHPFRC with and without confinement are proposed: (1) in situ casting of 25 mm thick UHPFRC jackets; (2) in situ casting of steel wire mesh-confined UHPFRC and (3) in situ casting of CFRP-confined UHPFRC. The confining action was achieved by sandwiching wire or CFRP mesh between two layers of UHPFRC. The results of this study indicate that BCJ specimens retrofitted with confined UHPFRC had improved overall seismic response, compared with specimens retrofitted only with UHPFRC. Further, the wire mesh-based retrofitting scheme proved to be more efficient than the CFRP mesh-based scheme.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47188673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Interfacial transition zone (ITZ) is significantly influenced by Water to Cementitious material ratio and governs the overall strength and fracture properties of concrete. Even though an ample number of studies on this line are available in the literature, there is a lack of unified conclusions pertaining to the influence of water-cement ratios on various fracture characteristics and the underlying mechanisms. In this study, an attempt has been made to investigate fracture characteristics such as,size of fracture process zone (FPZ) , fracture energy, traction free crack, toughening mechanisms, etc. in view of varying interfacial transition zone properties and water-cement ratio. Plain concrete beams of size 700×150×80 mm (L×D×B) with varying water-cement ratios have been considered and tested under centre point loading by controlling the crack mouth opening displacement. Acoustic emission (AE) technique has been used for understanding the internal damage parameters. A novel method has been proposed for identifying the traction free-crack tip and the FPZ size using AE event location data at different stages of loading. The role of ITZ on fracture mechanisms in different types of concrete has been critically discussed.Evaluation of fracture energy reveals that its relation with water-cement ratio is affected by the type of concrete.
{"title":"An improved understanding on the influence of water-cement ratio and ITZ on fracture mechanisms in concrete","authors":"D. Samal, S. Ray","doi":"10.1680/jmacr.22.00147","DOIUrl":"https://doi.org/10.1680/jmacr.22.00147","url":null,"abstract":"Interfacial transition zone (ITZ) is significantly influenced by Water to Cementitious material ratio and governs the overall strength and fracture properties of concrete. Even though an ample number of studies on this line are available in the literature, there is a lack of unified conclusions pertaining to the influence of water-cement ratios on various fracture characteristics and the underlying mechanisms. In this study, an attempt has been made to investigate fracture characteristics such as,size of fracture process zone (FPZ) , fracture energy, traction free crack, toughening mechanisms, etc. in view of varying interfacial transition zone properties and water-cement ratio. Plain concrete beams of size 700×150×80 mm (L×D×B) with varying water-cement ratios have been considered and tested under centre point loading by controlling the crack mouth opening displacement. Acoustic emission (AE) technique has been used for understanding the internal damage parameters. A novel method has been proposed for identifying the traction free-crack tip and the FPZ size using AE event location data at different stages of loading. The role of ITZ on fracture mechanisms in different types of concrete has been critically discussed.Evaluation of fracture energy reveals that its relation with water-cement ratio is affected by the type of concrete.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49603222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Martin, Amandine Bonnet, J. Renaud, R. Chlela, F. Toutlemonde, C. Sauvaget
Delayed Ettringite Formation (DEF) is strongly affected by moisture. Thus, understanding the effect of this parameter on the related degradations is of prime interest, not only for prevention strategies, but also for re-assessment of affected structures. While Alkali Aggregate Reaction (AAR) has deserved many research efforts on this aspect, understanding the effect of moisture on DEF still deserves to be studied, especially for exposure conditions being representative of field exposure. This paper describes an experimental program that aims to contribute to this objective. It consists in exposing concrete specimens with different DEF potentials to controlled moisture and water supply conditions, either constant or variable. The test results with these first conditions will help to determine coupling relations between moisture and expansion while test results of variable conditions will be used to benchmark these equations. To ensure exposure conditions as stable as possible, a specific experimental setup has been developed and is presented in this paper. Moreover, determination of the wetting-drying cycles applied to some specimens is presented and preliminary results are displayed and analysed.
{"title":"Influence of moisture on the development of delayed ettringite formation","authors":"R. Martin, Amandine Bonnet, J. Renaud, R. Chlela, F. Toutlemonde, C. Sauvaget","doi":"10.1680/jmacr.22.00282","DOIUrl":"https://doi.org/10.1680/jmacr.22.00282","url":null,"abstract":"Delayed Ettringite Formation (DEF) is strongly affected by moisture. Thus, understanding the effect of this parameter on the related degradations is of prime interest, not only for prevention strategies, but also for re-assessment of affected structures. While Alkali Aggregate Reaction (AAR) has deserved many research efforts on this aspect, understanding the effect of moisture on DEF still deserves to be studied, especially for exposure conditions being representative of field exposure. This paper describes an experimental program that aims to contribute to this objective. It consists in exposing concrete specimens with different DEF potentials to controlled moisture and water supply conditions, either constant or variable. The test results with these first conditions will help to determine coupling relations between moisture and expansion while test results of variable conditions will be used to benchmark these equations. To ensure exposure conditions as stable as possible, a specific experimental setup has been developed and is presented in this paper. Moreover, determination of the wetting-drying cycles applied to some specimens is presented and preliminary results are displayed and analysed.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42523137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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