Cement & concrete composites最新文献_第5页

X-ray computed tomography-based characterisation of graphene nanoplatelets re-agglomeration in hardened cement composites

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-02-05 DOI: 10.1016/j.cemconcomp.2025.105967

Zhaohua Wang , Meini Su , Yong Wang , Cise Unluer , Suning Li

Graphene Nanoplatelets (GNPs) have been found to be an effective additive for enhancing the mechanical strength of cementitious materials, attributed to the role they play as nucleation sites. However, there is not a direct correlation on the enhancing effect of graphene with increasing graphene dosage, resulting in different optimal dosages for different binders and mix designs. This study aims to develop a method to clarify the governing factor that determines the optimal graphene dosage in mortar mixes. X-ray computed tomography (XCT) was used to identify the size, surface area and distribution/re-agglomeration of graphene nanoplatelets in the prepared mixes. Compressive strength tests and TGA analysis were carried out to evaluate correlations among the total surface area of graphene nanoplatelets, mechanical performance, and cement hydration. Out of the three graphene dosages (0.035, 0.07, and 0.1 wt% by mass of cement) used in this study, samples with 0.07 wt% graphene revealed the highest total surface area of graphene nanoplatelets, hydration degree, and compressive strength. Results revealed that the enhancing effect of graphene addition in cement-based mixes was associated with the total surface area of the graphene nanoplatelets. A larger surface area contributed to stronger mechanical reinforcement by providing an increased number of nucleation sites in the pore solution.

{"title":"X-ray computed tomography-based characterisation of graphene nanoplatelets re-agglomeration in hardened cement composites","authors":"Zhaohua Wang , Meini Su , Yong Wang , Cise Unluer , Suning Li","doi":"10.1016/j.cemconcomp.2025.105967","DOIUrl":"10.1016/j.cemconcomp.2025.105967","url":null,"abstract":"<div><div>Graphene Nanoplatelets (GNPs) have been found to be an effective additive for enhancing the mechanical strength of cementitious materials, attributed to the role they play as nucleation sites. However, there is not a direct correlation on the enhancing effect of graphene with increasing graphene dosage, resulting in different optimal dosages for different binders and mix designs. This study aims to develop a method to clarify the governing factor that determines the optimal graphene dosage in mortar mixes. X-ray computed tomography (XCT) was used to identify the size, surface area and distribution/re-agglomeration of graphene nanoplatelets in the prepared mixes. Compressive strength tests and TGA analysis were carried out to evaluate correlations among the total surface area of graphene nanoplatelets, mechanical performance, and cement hydration. Out of the three graphene dosages (0.035, 0.07, and 0.1 wt% by mass of cement) used in this study, samples with 0.07 wt% graphene revealed the highest total surface area of graphene nanoplatelets, hydration degree, and compressive strength. Results revealed that the enhancing effect of graphene addition in cement-based mixes was associated with the total surface area of the graphene nanoplatelets. A larger surface area contributed to stronger mechanical reinforcement by providing an increased number of nucleation sites in the pore solution.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"158 ","pages":"Article 105967"},"PeriodicalIF":10.8,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143192359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Innovative ZIF-8 modified ER@EC microcapsules: Enhancing slow-release and longevity for superior self-healing in cementitious materials

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-02-04 DOI: 10.1016/j.cemconcomp.2025.105966

Shiyu Zhang , Zijian Song , Haoliang Zhang , Zilang Huang , Hui Rong , Linhua Jiang , Yunsheng Zhang

Using microcapsules (MCs) for self-healing is one of the most cutting-edge strategies for repairing concrete cracks and improving the durability of reinforced concrete (RC) structures. MCs with ethyl cellulose (EC) as the shell material possess non-toxicity, high stability, and satisfactory encapsulation capacity. However, EC-based MCs suffer from the premature release of core materials due to their porous nature. This study synthesized the zeolitic imidazolate framework-8 (ZIF-8) and embedded it into the EC shell to enable a long-acting healing function of epoxy resin (ER) @ EC MCs. The morphology, thermal stability, chemical structure, release rates, and particle size of the ER@EC/ZIF-8 MCs were evaluated. The first and secondary self-healing performances of mortars with different MC dosages were determined. The results demonstrated the successful embedding of ZIF-8 into the MCs, with a 20 % dosage of ZIF-8 modification achieving the most sustained release. Furthermore, ER@EC/ZIF-8 MCs effectively reduced pores larger than 77.45 nm and decreased the overall porosity by 3.13 %. ZIF-8 modification enhanced strength healing, particularly the long-acting aspect, with the secondary healing rate peaking at 31.48 % at a 3 % dosage of modified MCs under dual 30 % f_c0 pre-damage. Meanwhile, the highest first healing rate (22.02 %) was also observed at a dosage of 3 % modified MCs under 30 % f_c0 pre-damage. Generally, the modified MCs showed a superior healing effect than the unmodified MCs. As a newly developed self-healing MC, the ER@EC/ZIF-8 MCs are expected to confer multifunctional properties to RC structures.

{"title":"Innovative ZIF-8 modified ER@EC microcapsules: Enhancing slow-release and longevity for superior self-healing in cementitious materials","authors":"Shiyu Zhang , Zijian Song , Haoliang Zhang , Zilang Huang , Hui Rong , Linhua Jiang , Yunsheng Zhang","doi":"10.1016/j.cemconcomp.2025.105966","DOIUrl":"10.1016/j.cemconcomp.2025.105966","url":null,"abstract":"<div><div>Using microcapsules (MCs) for self-healing is one of the most cutting-edge strategies for repairing concrete cracks and improving the durability of reinforced concrete (RC) structures. MCs with ethyl cellulose (EC) as the shell material possess non-toxicity, high stability, and satisfactory encapsulation capacity. However, EC-based MCs suffer from the premature release of core materials due to their porous nature. This study synthesized the zeolitic imidazolate framework-8 (ZIF-8) and embedded it into the EC shell to enable a long-acting healing function of epoxy resin (ER) @ EC MCs. The morphology, thermal stability, chemical structure, release rates, and particle size of the ER@EC/ZIF-8 MCs were evaluated. The first and secondary self-healing performances of mortars with different MC dosages were determined. The results demonstrated the successful embedding of ZIF-8 into the MCs, with a 20 % dosage of ZIF-8 modification achieving the most sustained release. Furthermore, ER@EC/ZIF-8 MCs effectively reduced pores larger than 77.45 nm and decreased the overall porosity by 3.13 %. ZIF-8 modification enhanced strength healing, particularly the long-acting aspect, with the secondary healing rate peaking at 31.48 % at a 3 % dosage of modified MCs under dual 30 % <em>f</em><sub>c0</sub> pre-damage. Meanwhile, the highest first healing rate (22.02 %) was also observed at a dosage of 3 % modified MCs under 30 % <em>f</em><sub>c0</sub> pre-damage. Generally, the modified MCs showed a superior healing effect than the unmodified MCs. As a newly developed self-healing MC, the ER@EC/ZIF-8 MCs are expected to confer multifunctional properties to RC structures.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"158 ","pages":"Article 105966"},"PeriodicalIF":10.8,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143083146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A novel electromigration-based microbial self-healing strategy for existing concrete structures

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-02-04 DOI: 10.1016/j.cemconcomp.2025.105965

Zhenxiao Bi , Jing Xu , Hao Sun , Qing Chen , Hehua Zhu

The prevailing self-healing of concrete cracks based on microbial-induced carbonate precipitation (MICP) has been limited to new structures since healing agents have to be pre-embedded during fresh mixing stage. In this study, a novel microbial self-healing strategy based on electromigration of bacterial spores is proposed for existing concrete. To this end, the feasibility of this new method is first verified, and the self-healing performances of the microbial mortar based on electromigration of spores are assessed. Results reveal that the applied electric field improves the physiological activity of spores but not affects the mineralogy and morphology of biomineralized products. Although a prolonged electrical treatment time or an enhanced electric field intensity results in a loss of physiological activity, the number of spores migrated into the mortar increases. The viability of spores is well preserved upon electromigration, and most of the spores are identified in the subsurface layer of the mortar with a thickness over 200 μm. With an electric field intensity of 1 V/cm and treatment time longer than 18 h, the crack width and crack area healing ratios for initial cracks within 600 μm were close to 100 %, and the resistance coefficient to water penetration improves by nearly 4 orders of magnitude. This study successfully extends the application scenarios of microbial self-healing of concrete.

{"title":"A novel electromigration-based microbial self-healing strategy for existing concrete structures","authors":"Zhenxiao Bi , Jing Xu , Hao Sun , Qing Chen , Hehua Zhu","doi":"10.1016/j.cemconcomp.2025.105965","DOIUrl":"10.1016/j.cemconcomp.2025.105965","url":null,"abstract":"<div><div>The prevailing self-healing of concrete cracks based on microbial-induced carbonate precipitation (MICP) has been limited to new structures since healing agents have to be pre-embedded during fresh mixing stage. In this study, a novel microbial self-healing strategy based on electromigration of bacterial spores is proposed for existing concrete. To this end, the feasibility of this new method is first verified, and the self-healing performances of the microbial mortar based on electromigration of spores are assessed. Results reveal that the applied electric field improves the physiological activity of spores but not affects the mineralogy and morphology of biomineralized products. Although a prolonged electrical treatment time or an enhanced electric field intensity results in a loss of physiological activity, the number of spores migrated into the mortar increases. The viability of spores is well preserved upon electromigration, and most of the spores are identified in the subsurface layer of the mortar with a thickness over 200 μm. With an electric field intensity of 1 V/cm and treatment time longer than 18 h, the crack width and crack area healing ratios for initial cracks within 600 μm were close to 100 %, and the resistance coefficient to water penetration improves by nearly 4 orders of magnitude. This study successfully extends the application scenarios of microbial self-healing of concrete.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"158 ","pages":"Article 105965"},"PeriodicalIF":10.8,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143083147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Prediction of microbial-induced calcium carbonate precipitation for self-healing cementitious material

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-02-03 DOI: 10.1016/j.cemconcomp.2025.105945

Hsiao Wei Lee , Seyed Ali Rahmaninezhad , Li Meng , Wil V. Srubar III , Christopher M. Sales , Yaghoob (Amir) Farnam , Mija H. Hubler , Ahmad R. Najafi

Microbial-induced calcium carbonate precipitation (MICCP) is a biomineralization process utilizing microbial metabolic activities to precipitate calcium carbonate (CaCO₃). In recent years, there has been increasing interest in the application of MICCP in self-healing cementitious materials. In this research, the chemical and enzyme kinetics of MICCP were numerically modeled, focusing on the ureolytic bacteria responsible for the ureolysis reaction, which facilitates the precipitation of CaCO₃. The model considers the growth and decay of bacteria, the ureolysis reaction catalyzed by the urease enzyme of the bacteria, the shift in bicarbonate equilibrium due to pH variation of the solution, and the calcium carbonate precipitation. In the simulation, the concentration of chemicals and bacteria as a function of time was computed. Additionally, the distribution of chemicals due to fluid transport were determined. The capability of the model was demonstrated through several benchmark simulations, including its application in self-healing concrete with a vascularized channel system. Experimental studies were also conducted to first calibrate the model parameters and then validate the model results. The predicted CaCO₃ precipitation defines a crack filling ratio,

h_{d}

, which is discussed in many damage-healing literature. Once the mechanical properties of MICCPs are determined, the strength recovery of self-healing concrete incorporating MICCP can then be further modeled.

{"title":"Prediction of microbial-induced calcium carbonate precipitation for self-healing cementitious material","authors":"Hsiao Wei Lee , Seyed Ali Rahmaninezhad , Li Meng , Wil V. Srubar III , Christopher M. Sales , Yaghoob (Amir) Farnam , Mija H. Hubler , Ahmad R. Najafi","doi":"10.1016/j.cemconcomp.2025.105945","DOIUrl":"10.1016/j.cemconcomp.2025.105945","url":null,"abstract":"<div><div>Microbial-induced calcium carbonate precipitation (MICCP) is a biomineralization process utilizing microbial metabolic activities to precipitate calcium carbonate (CaCO<sub>3</sub>). In recent years, there has been increasing interest in the application of MICCP in self-healing cementitious materials. In this research, the chemical and enzyme kinetics of MICCP were numerically modeled, focusing on the ureolytic bacteria responsible for the ureolysis reaction, which facilitates the precipitation of CaCO<sub>3</sub>. The model considers the growth and decay of bacteria, the ureolysis reaction catalyzed by the urease enzyme of the bacteria, the shift in bicarbonate equilibrium due to pH variation of the solution, and the calcium carbonate precipitation. In the simulation, the concentration of chemicals and bacteria as a function of time was computed. Additionally, the distribution of chemicals due to fluid transport were determined. The capability of the model was demonstrated through several benchmark simulations, including its application in self-healing concrete with a vascularized channel system. Experimental studies were also conducted to first calibrate the model parameters and then validate the model results. The predicted CaCO<sub>3</sub> precipitation defines a crack filling ratio, <span><math><msub><mrow><mi>h</mi></mrow><mrow><mi>d</mi></mrow></msub></math></span>, which is discussed in many damage-healing literature. Once the mechanical properties of MICCPs are determined, the strength recovery of self-healing concrete incorporating MICCP can then be further modeled.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"158 ","pages":"Article 105945"},"PeriodicalIF":10.8,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effects and mechanisms of the hybrid-modified SAP with calcium sulfate dihydrate on the properties of UHPC

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-01-31 DOI: 10.1016/j.cemconcomp.2025.105962

Deyu Kong , Zhentao Han , Zhiyang Chen , Chenxu Ni , Haotian Wu , Yaqian Liang , Kui He , Jintao Liu

In the synthesis process of superabsorbent polymer (SAP), calcium sulfate dihydrate (C$H₂) dispersion in water or colloidal silica sol (CSS) was used for the modification of SAP. The effects of modification on water absorption of SAP in water or saturated calcium hydroxide (CH) solution and the impacts and mechanism of the modified SAP on the performance of UHPC were investigated. The results showed that the modification results in a significant decrease in water absorption in both tap water and saturated CH solution for the SAP with water-based dispersion, but an increase in saturated CH solution though a decrease in tap water for that with the CSS-based dispersion. The SEM observation showed that a large amount of long ettringite crystals formed around the voids left by the SAP modified with the water-based dispersion. However, few ettringite crystals but more hydration products were observed to fill in the voids and a C-S-H gel shell-structure was also found in the voids left by the SAP modified with the CSS-based dispersion. Because of these, it was interestingly found that the crack resistance was further improved and a significant improvement in both flexural and compressive strength was observed, though the internal curing effect was weakened because some internal curing water carried by the SAP was consumed during the formation of the ettringite crystals and the C-S-H gels in the voids.

{"title":"Effects and mechanisms of the hybrid-modified SAP with calcium sulfate dihydrate on the properties of UHPC","authors":"Deyu Kong , Zhentao Han , Zhiyang Chen , Chenxu Ni , Haotian Wu , Yaqian Liang , Kui He , Jintao Liu","doi":"10.1016/j.cemconcomp.2025.105962","DOIUrl":"10.1016/j.cemconcomp.2025.105962","url":null,"abstract":"<div><div>In the synthesis process of superabsorbent polymer (SAP), calcium sulfate dihydrate (C$H<sub>2</sub>) dispersion in water or colloidal silica sol (CSS) was used for the modification of SAP. The effects of modification on water absorption of SAP in water or saturated calcium hydroxide (CH) solution and the impacts and mechanism of the modified SAP on the performance of UHPC were investigated. The results showed that the modification results in a significant decrease in water absorption in both tap water and saturated CH solution for the SAP with water-based dispersion, but an increase in saturated CH solution though a decrease in tap water for that with the CSS-based dispersion. The SEM observation showed that a large amount of long ettringite crystals formed around the voids left by the SAP modified with the water-based dispersion. However, few ettringite crystals but more hydration products were observed to fill in the voids and a C-S-H gel shell-structure was also found in the voids left by the SAP modified with the CSS-based dispersion. Because of these, it was interestingly found that the crack resistance was further improved and a significant improvement in both flexural and compressive strength was observed, though the internal curing effect was weakened because some internal curing water carried by the SAP was consumed during the formation of the ettringite crystals and the C-S-H gels in the voids.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"157 ","pages":"Article 105962"},"PeriodicalIF":10.8,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143071710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Relation between pore structure uniformity and compressive strength of iron tailings mortar

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-01-31 DOI: 10.1016/j.cemconcomp.2025.105964

Yi Li, Mengxuan Yu, Wei Li, Xin Bian

Pore structure uniformity is one of the key factors affecting the compressive strength of mortar. This study proposed two new methods to characterize the uniformity of pore distribution and established their relationship with compressive strength. Compressive and pore structure tests were carried out on ordinary mortar, iron tailings mortar, and iron tailings mortar containing basalt fibers and polyacrylate emulsion. The first method uses the quadrat-based method calculated based on pore area and regional distribution, while the second method utilizes the average nearest neighbor index determined based on the distance between pore boundaries. Correlation analysis was used to model the relation between pore distribution uniformity and compressive strength. The results showed that iron tailings, basalt fibers and polyacrylate emulsion all reduced the compressive strength and pore distribution uniformity of mortar. The standard deviation of porosity and the average nearest neighbor index can accurately characterize the uniformity of pore distribution of mortar. Both methods show strong linear correlations with the compressive strength, in particular with the average nearest neighbor index. By introducing new methods to accurately characterize the uniformity of the pore distribution of mortar, this study provides the theoretical basis for in-depth understanding of the influence of pores on the macroscopic properties of materials.

{"title":"Relation between pore structure uniformity and compressive strength of iron tailings mortar","authors":"Yi Li, Mengxuan Yu, Wei Li, Xin Bian","doi":"10.1016/j.cemconcomp.2025.105964","DOIUrl":"10.1016/j.cemconcomp.2025.105964","url":null,"abstract":"<div><div>Pore structure uniformity is one of the key factors affecting the compressive strength of mortar. This study proposed two new methods to characterize the uniformity of pore distribution and established their relationship with compressive strength. Compressive and pore structure tests were carried out on ordinary mortar, iron tailings mortar, and iron tailings mortar containing basalt fibers and polyacrylate emulsion. The first method uses the quadrat-based method calculated based on pore area and regional distribution, while the second method utilizes the average nearest neighbor index determined based on the distance between pore boundaries. Correlation analysis was used to model the relation between pore distribution uniformity and compressive strength. The results showed that iron tailings, basalt fibers and polyacrylate emulsion all reduced the compressive strength and pore distribution uniformity of mortar. The standard deviation of porosity and the average nearest neighbor index can accurately characterize the uniformity of pore distribution of mortar. Both methods show strong linear correlations with the compressive strength, in particular with the average nearest neighbor index. By introducing new methods to accurately characterize the uniformity of the pore distribution of mortar, this study provides the theoretical basis for in-depth understanding of the influence of pores on the macroscopic properties of materials.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"157 ","pages":"Article 105964"},"PeriodicalIF":10.8,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143071709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Integrated assessment of magnesium phosphate cement repaired concrete from the perspective of mechanical, geometric and electrochemical compatibility

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-01-30 DOI: 10.1016/j.cemconcomp.2025.105958

Sijia Liu , Ken Yang , Long Yu , Linglin Xu , Qiang Yuan , Kai Wu , Zhenghong Yang

Magnesium phosphate cement (MPC) has gained more and more attention in the field of rapid repair and strengthening of normal concrete and reinforced concrete structures. Although the performance of MPC itself is of great concern, its compatibility with existing concrete is poorly understood. An effective testing method is necessary to assess the reliability of utilizing MPC mortar repairing construction comprehensively. In this work, systematic assessment methods regarding the mechanical, geometric and electrochemical compatibility between MPC repair mortar and concrete substrate were proposed. Five interesting repaired patterns were designed. The observed results showed that the composite system demonstrates excellent interfacial bonding and overall mechanical properties. The 3-h bond strength of the vertical repair interface repaired pattern reached 3.1 MPa, and comparable or even higher flexural strength was observed in the horizontal interface and compound interface repaired patterns. A novel MPC-NC ring was employed to monitor the interface bond stress evolution, which is a time-dependent function that develops rapidly in the early stages and is affected by relative humidity. The steel rebar in the repaired system (half repair mortar/half concrete substrate) exhibited superior corrosion protection even after 180 days of exposure in 3.5 wt% NaCl solution. The electrochemical compatibility mechanism can be contributed to the passivation process and the inhibition of charge transfer in the repaired area. This study lays a solid foundation for applying MPC repair material in practical engineering and carries out a compatibility evaluation.

{"title":"Integrated assessment of magnesium phosphate cement repaired concrete from the perspective of mechanical, geometric and electrochemical compatibility","authors":"Sijia Liu , Ken Yang , Long Yu , Linglin Xu , Qiang Yuan , Kai Wu , Zhenghong Yang","doi":"10.1016/j.cemconcomp.2025.105958","DOIUrl":"10.1016/j.cemconcomp.2025.105958","url":null,"abstract":"<div><div>Magnesium phosphate cement (MPC) has gained more and more attention in the field of rapid repair and strengthening of normal concrete and reinforced concrete structures. Although the performance of MPC itself is of great concern, its compatibility with existing concrete is poorly understood. An effective testing method is necessary to assess the reliability of utilizing MPC mortar repairing construction comprehensively. In this work, systematic assessment methods regarding the mechanical, geometric and electrochemical compatibility between MPC repair mortar and concrete substrate were proposed. Five interesting repaired patterns were designed. The observed results showed that the composite system demonstrates excellent interfacial bonding and overall mechanical properties. The 3-h bond strength of the vertical repair interface repaired pattern reached 3.1 MPa, and comparable or even higher flexural strength was observed in the horizontal interface and compound interface repaired patterns. A novel MPC-NC ring was employed to monitor the interface bond stress evolution, which is a time-dependent function that develops rapidly in the early stages and is affected by relative humidity. The steel rebar in the repaired system (half repair mortar/half concrete substrate) exhibited superior corrosion protection even after 180 days of exposure in 3.5 wt% NaCl solution. The electrochemical compatibility mechanism can be contributed to the passivation process and the inhibition of charge transfer in the repaired area. This study lays a solid foundation for applying MPC repair material in practical engineering and carries out a compatibility evaluation.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"157 ","pages":"Article 105958"},"PeriodicalIF":10.8,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143071711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Improving the performance of SiO2 nanoparticles in portland-limestone cementitious systems using silica-limestone composites

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-01-29 DOI: 10.1016/j.cemconcomp.2025.105961

Qitong Liu , Payam Hosseini , Bu Wang

This study examines the effectiveness of doping SiO₂ nanoparticles onto limestone substrates to mitigate nanoparticle agglomeration, thereby enhancing their performance through improved dispersion within the cement paste matrix. SiO₂ nanoparticles were doped onto the limestone particles using the wet doping method, and the resulting SiO₂-nanoparticle-limestone composite was incorporated into cement paste systems. To thoroughly examine the effects of SiO₂-nanoparticle-limestone composite on the properties of cement paste mixtures, SiO₂ nanoparticles with two different specific surface areas (90 m²/g and 300 m²/g) and at various dosages (1.4 %, 2.8 %, and 5.6 % by weight of the total binder) were doped onto the limestone particles. Results show that doping SiO₂ nanoparticles onto the limestone particles reduced the required amount of superplasticizer, decreased calcium hydroxide content through intensified pozzolanic activity, refined the pore structure, and enhanced compressive strength in cement paste systems, compared to the direct addition of colloidal SiO₂ nanoparticles during mixing process. These findings suggest that the SiO₂-nanoparticle-doped limestone composite has the potential to develop cement-based materials with substantially reduced clinker content, enhanced mechanical strength, and a refined pore structure.

{"title":"Improving the performance of SiO2 nanoparticles in portland-limestone cementitious systems using silica-limestone composites","authors":"Qitong Liu , Payam Hosseini , Bu Wang","doi":"10.1016/j.cemconcomp.2025.105961","DOIUrl":"10.1016/j.cemconcomp.2025.105961","url":null,"abstract":"<div><div>This study examines the effectiveness of doping SiO<sub>2</sub> nanoparticles onto limestone substrates to mitigate nanoparticle agglomeration, thereby enhancing their performance through improved dispersion within the cement paste matrix. SiO<sub>2</sub> nanoparticles were doped onto the limestone particles using the wet doping method, and the resulting SiO<sub>2</sub>-nanoparticle-limestone composite was incorporated into cement paste systems. To thoroughly examine the effects of SiO<sub>2</sub>-nanoparticle-limestone composite on the properties of cement paste mixtures, SiO<sub>2</sub> nanoparticles with two different specific surface areas (90 m<sup>2</sup>/g and 300 m<sup>2</sup>/g) and at various dosages (1.4 %, 2.8 %, and 5.6 % by weight of the total binder) were doped onto the limestone particles. Results show that doping SiO<sub>2</sub> nanoparticles onto the limestone particles reduced the required amount of superplasticizer, decreased calcium hydroxide content through intensified pozzolanic activity, refined the pore structure, and enhanced compressive strength in cement paste systems, compared to the direct addition of colloidal SiO<sub>2</sub> nanoparticles during mixing process. These findings suggest that the SiO<sub>2</sub>-nanoparticle-doped limestone composite has the potential to develop cement-based materials with substantially reduced clinker content, enhanced mechanical strength, and a refined pore structure.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"157 ","pages":"Article 105961"},"PeriodicalIF":10.8,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143055592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Improved microstructure and compressive strength of pastes and mortars containing MgO-SiO2 cement produced by combined calcination of MgCO3 and kaolin

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-01-28 DOI: 10.1016/j.cemconcomp.2025.105959

J.P.B. Batista , G.C. Cordeiro , L.F. Ribeiro , J.C.B. Moraes

MgO-SiO₂ cement was produced by combined calcination of MgCO₃ and kaolin as raw materials, at a MgCO₃/kaolin mass ratio of 3.0 and 800 °C for 45 min. Separate calcination of MgCO₃ and kaolin was also conducted under the same conditions. Raw materials were characterized based on their chemical composition, bulk density, particle size distribution, XRD, FTIR, and BET specific surface area, and the MgO-SiO₂ cement produced was analyzed using XRD, FTIR, SEM/EDS, BET specific surface area, and particle size distribution. Pastes were produced to characterize microstructure and the reaction process (XRD, FTIR, TGA, isothermal calorimetry, chemical shrinkage, and SEM/EDS), and mortars to assess compressive strength. The results of BET and SEM/EDS analyses of the cements confirmed that combined calcination increased particle adhesion. Microstructural analyses of pastes after 28 days of curing at 25 °C showed the formation of a dense matrix of M-A-S-H reaction product, with aluminum incorporated into the M-A-S-H structure; brucite and hydrotalcite were also generated after the reaction process. Paste reaction results demonstrated that combined calcination produced cement with a higher degree of reaction after 72 h at 25 °C. The highest compressive strength (42.0 MPa) in mortars obtained by combined calcination was recorded after 28 days of curing at 25 °C, 223 % higher than that of separately calcined cement (13.0 MPa). As such, this study successfully applied combined calcination to produce a more strength MgO-SiO₂ cement.

{"title":"Improved microstructure and compressive strength of pastes and mortars containing MgO-SiO2 cement produced by combined calcination of MgCO3 and kaolin","authors":"J.P.B. Batista , G.C. Cordeiro , L.F. Ribeiro , J.C.B. Moraes","doi":"10.1016/j.cemconcomp.2025.105959","DOIUrl":"10.1016/j.cemconcomp.2025.105959","url":null,"abstract":"<div><div>MgO-SiO<sub>2</sub> cement was produced by combined calcination of MgCO<sub>3</sub> and kaolin as raw materials, at a MgCO<sub>3</sub>/kaolin mass ratio of 3.0 and 800 °C for 45 min. Separate calcination of MgCO<sub>3</sub> and kaolin was also conducted under the same conditions. Raw materials were characterized based on their chemical composition, bulk density, particle size distribution, XRD, FTIR, and BET specific surface area, and the MgO-SiO<sub>2</sub> cement produced was analyzed using XRD, FTIR, SEM/EDS, BET specific surface area, and particle size distribution. Pastes were produced to characterize microstructure and the reaction process (XRD, FTIR, TGA, isothermal calorimetry, chemical shrinkage, and SEM/EDS), and mortars to assess compressive strength. The results of BET and SEM/EDS analyses of the cements confirmed that combined calcination increased particle adhesion. Microstructural analyses of pastes after 28 days of curing at 25 °C showed the formation of a dense matrix of M-A-S-H reaction product, with aluminum incorporated into the M-A-S-H structure; brucite and hydrotalcite were also generated after the reaction process. Paste reaction results demonstrated that combined calcination produced cement with a higher degree of reaction after 72 h at 25 °C. The highest compressive strength (42.0 MPa) in mortars obtained by combined calcination was recorded after 28 days of curing at 25 °C, 223 % higher than that of separately calcined cement (13.0 MPa). As such, this study successfully applied combined calcination to produce a more strength MgO-SiO<sub>2</sub> cement.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"157 ","pages":"Article 105959"},"PeriodicalIF":10.8,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143050073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Corrosion resistance of zinc in a low-carbon binder with belitic calcium sulfoaluminate cement

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-01-27 DOI: 10.1016/j.cemconcomp.2025.105956

Wenxuan Li, Jinjie Shi

This study investigated the passivation ability and chloride-induced corrosion behavior of galvanized steel in the pore solutions of belitic calcium sulfoaluminate (BCSA) cement. Pure zinc was used to simulate the galvanized coating, and ordinary Portland cement (OPC) solution was also tested for the comparison purpose. A comparable passivation behavior was observed for pure zinc in the OPC solution and a mixture solution of 50 % OPC and 50 % BCSA cement (abbreviated as PSA solution). On the one hand, due to the high Ca²⁺ ion concentration and low alkalinity of the PSA solution, which is conducive to zinc passivity, a more stable protective layer of calcium hydroxyzincate (CHZ) was generated on the zinc surface. On the other hand, the passivation ability of zinc was reduced to some extent by the high SO₄²⁻ ion concentration in the PSA solution. During the corrosion stage induced by exogenous chlorides, a different variation tendency was found for the corrosion resistance of zinc in OPC and PSA solutions over exposure time. Owing to the synergetic attack by SO₄²⁻ and Cl⁻ ions, the critical chloride concentration of zinc in the PSA solution was only 0.3 M, as determined by a sharp drop of E_corr and R_p values, while zinc in the OPC solution exhibited a much higher chloride resistance with the critical chloride concentration of 0.8 M. However, this detrimental effect on the corrosion resistance of zinc in the PSA solution was less pronounced with prolonged exposure due to the formation of protective corrosion products.

{"title":"Corrosion resistance of zinc in a low-carbon binder with belitic calcium sulfoaluminate cement","authors":"Wenxuan Li, Jinjie Shi","doi":"10.1016/j.cemconcomp.2025.105956","DOIUrl":"10.1016/j.cemconcomp.2025.105956","url":null,"abstract":"<div><div>This study investigated the passivation ability and chloride-induced corrosion behavior of galvanized steel in the pore solutions of belitic calcium sulfoaluminate (BCSA) cement. Pure zinc was used to simulate the galvanized coating, and ordinary Portland cement (OPC) solution was also tested for the comparison purpose. A comparable passivation behavior was observed for pure zinc in the OPC solution and a mixture solution of 50 % OPC and 50 % BCSA cement (abbreviated as PSA solution). On the one hand, due to the high Ca<sup>2+</sup> ion concentration and low alkalinity of the PSA solution, which is conducive to zinc passivity, a more stable protective layer of calcium hydroxyzincate (CHZ) was generated on the zinc surface. On the other hand, the passivation ability of zinc was reduced to some extent by the high SO<sub>4</sub><sup>2−</sup> ion concentration in the PSA solution. During the corrosion stage induced by exogenous chlorides, a different variation tendency was found for the corrosion resistance of zinc in OPC and PSA solutions over exposure time. Owing to the synergetic attack by SO<sub>4</sub><sup>2−</sup> and Cl<sup>−</sup> ions, the critical chloride concentration of zinc in the PSA solution was only 0.3 M, as determined by a sharp drop of <em>E</em><sub>corr</sub> and <em>R</em><sub>p</sub> values, while zinc in the OPC solution exhibited a much higher chloride resistance with the critical chloride concentration of 0.8 M. However, this detrimental effect on the corrosion resistance of zinc in the PSA solution was less pronounced with prolonged exposure due to the formation of protective corrosion products.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"157 ","pages":"Article 105956"},"PeriodicalIF":10.8,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143044283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0