Pub Date : 2024-11-16DOI: 10.1016/j.conbuildmat.2024.139154
Yaomin Gao , Gelong Xu , Jiwei Cai , Qing Tian , Ruixue Liu , Jiaqi Zhang , Zixuan Du
The effect of fly ash (FA) and glass powder (GP) as siliceous materials on the strength, hydration products and microstructure of autoclaved materials are investigated. The results indicated that GP is more beneficial to the growth of compressive strength than FA. At the Ca/Si ratio of 0.7, the compressive strength of the GP mixture is 95.7 % higher than that of the FA mixture, and the compressive strength presents a monotonously increasing trend with the increase of the GP replacement ratio for FA. The silica in GP has a higher reactivity than FA to form more hydration products. The main hydration product in the GP mixture is mainly the amorphous C-S-H with a lower Ca/Si ratio, which is difficult to crystalize and transform into tobermorite. FA facilitates the formation of tobermorite, and with the substitution of GP for FA, the fibrous tobermorite is displaced by sheet-like tobermorite and even the foil-like phases at a high GP substitution ratio. Furthermore, the hydration products in the GP mixture have a lower density than that in the FA mixture, but it is conducive to reducing the porosity of the autoclaved material. The low porosity is an important reason that GP as siliceous raw material is eligible for preparing high-strength autoclaved material.
研究了粉煤灰（FA）和玻璃粉（GP）作为硅质材料对蒸压材料强度、水化产物和微观结构的影响。结果表明，GP 比 FA 更有利于抗压强度的增长。在 Ca/Si 比为 0.7 时，GP 混合物的抗压强度比 FA 混合物高 95.7%，并且抗压强度随着 GP 替代 FA 比例的增加呈单调上升趋势。GP 中的二氧化硅比 FA 具有更高的反应活性，能形成更多的水化产物。GP 混合物中的主要水化产物主要是 Ca/Si 比值较低的无定形 C-S-H，它很难结晶并转化成托勃莫来石。FA 有利于托勃莫来石的形成，随着 GP 取代 FA，纤维状托勃莫来石被片状托勃莫来石取代，甚至在 GP 取代率较高时，箔状相也会被取代。此外，GP 混合物中的水合产物密度低于 FA 混合物，但有利于降低蒸压材料的孔隙率。低孔隙率是 GP 作为硅质原料可用于制备高强度蒸压材料的重要原因。
{"title":"Comparison of waste glass and fly ash as silica sources for autoclaved materials","authors":"Yaomin Gao , Gelong Xu , Jiwei Cai , Qing Tian , Ruixue Liu , Jiaqi Zhang , Zixuan Du","doi":"10.1016/j.conbuildmat.2024.139154","DOIUrl":"10.1016/j.conbuildmat.2024.139154","url":null,"abstract":"<div><div>The effect of fly ash (FA) and glass powder (GP) as siliceous materials on the strength, hydration products and microstructure of autoclaved materials are investigated. The results indicated that GP is more beneficial to the growth of compressive strength than FA. At the Ca/Si ratio of 0.7, the compressive strength of the GP mixture is 95.7 % higher than that of the FA mixture, and the compressive strength presents a monotonously increasing trend with the increase of the GP replacement ratio for FA. The silica in GP has a higher reactivity than FA to form more hydration products. The main hydration product in the GP mixture is mainly the amorphous C-S-H with a lower Ca/Si ratio, which is difficult to crystalize and transform into tobermorite. FA facilitates the formation of tobermorite, and with the substitution of GP for FA, the fibrous tobermorite is displaced by sheet-like tobermorite and even the foil-like phases at a high GP substitution ratio. Furthermore, the hydration products in the GP mixture have a lower density than that in the FA mixture, but it is conducive to reducing the porosity of the autoclaved material. The low porosity is an important reason that GP as siliceous raw material is eligible for preparing high-strength autoclaved material.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139154"},"PeriodicalIF":7.4,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663776","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}
The inclusion of bacteria in developing advanced, self-sensing, and self-healing cement-based materials in crack healing is a sustainable and innovative approach in Civil Engineering applications. As a response to the surrounding environment, the bacterial metabolism leads to microbially induced calcium carbonate precipitation (MICCP). This phenomenon is mostly prevalent with genus Bacillus and other genera. Bacteria being ubiquitous, survive in different environmental conditions, and can precipitate calcium carbonate through different biochemical pathways. Largely, (ureolytic) and (non-ureolytic) bacteria are studied for calcium carbonate precipitation in the cracks and heal them sustainably. Though immense work has been done and published in this domain, the technology transfer from lab-scale to meso-scale has been inefficient due to various factors. Primarily, the bacteria’s specific growth conditions such as optimum pH, temperature, humidity, oxygen availability could limit the translation of this technology to the real-world. Secondly, parameters such as water quality used for mixing of the cementitious materials, curing conditions, incubation time and temperature, and humidity vary from lab to lab causing diverse observations. Thirdly, the BBSHCM's formulation with lab-grade chemicals is expensive. The researchers are exploring alternative nutrient substitutes. Enormous literature ranging from meso to macro-scale studies has been published. This review is a wide-ranging effort to compile the knowledge from published literature on the roles of ureolytic and non-ureolytic bacteria in calcite formation, the problems associated with the delivery of bio-healants at the site of damage, impact of MICCP bacteria on the healing ability and mechanical properties of cementitious material, studies from various field trials, and the economic viability of these systems are discussed and summarised at the end. The aim is to present a comprehensive understanding of the concept of bacteria-based self-healing cementitious material (BBSHCM). To conclude, the variations in results and prospects are recognized and proposed in the final section.
{"title":"Probing the Abyss: Bacteria-based self-healing in cementitious construction materials – A Review","authors":"Trupti Sharma , Anirban Banerjee , Prakash Nanthagopalan","doi":"10.1016/j.conbuildmat.2024.139054","DOIUrl":"10.1016/j.conbuildmat.2024.139054","url":null,"abstract":"<div><div>The inclusion of bacteria in developing advanced, self-sensing, and self-healing cement-based materials in crack healing is a sustainable and innovative approach in Civil Engineering applications. As a response to the surrounding environment, the bacterial metabolism leads to microbially induced calcium carbonate precipitation (MICCP). This phenomenon is mostly prevalent with genus <em>Bacillus</em> and other genera. Bacteria being ubiquitous, survive in different environmental conditions, and can precipitate calcium carbonate through different biochemical pathways. Largely, (ureolytic) and (non-ureolytic) bacteria are studied for calcium carbonate precipitation in the cracks and heal them sustainably. Though immense work has been done and published in this domain, the technology transfer from lab-scale to meso-scale has been inefficient due to various factors. Primarily, the bacteria’s specific growth conditions such as optimum pH, temperature, humidity, oxygen availability could limit the translation of this technology to the real-world. Secondly, parameters such as water quality used for mixing of the cementitious materials, curing conditions, incubation time and temperature, and humidity vary from lab to lab causing diverse observations. Thirdly, the BBSHCM's formulation with lab-grade chemicals is expensive. The researchers are exploring alternative nutrient substitutes. Enormous literature ranging from meso to macro-scale studies has been published. This review is a wide-ranging effort to compile the knowledge from published literature on the roles of ureolytic and non-ureolytic bacteria in calcite formation, the problems associated with the delivery of bio-healants at the site of damage, impact of MICCP bacteria on the healing ability and mechanical properties of cementitious material, studies from various field trials, and the economic viability of these systems are discussed and summarised at the end. The aim is to present a comprehensive understanding of the concept of bacteria-based self-healing cementitious material (BBSHCM). To conclude, the variations in results and prospects are recognized and proposed in the final section.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139054"},"PeriodicalIF":7.4,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664090","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}
Pub Date : 2024-11-16DOI: 10.1016/j.conbuildmat.2024.139214
Ziyi Wang , Yue Yuan , Xiang Zhang , Bin Zeng , Chun-Lin Wang
Laser cladding (LC) technology has garnered significant attention for its application in the repair of corrosion damage in steel structures. However, research on the high-cycle fatigue performance of LC materials remains limited. This study employed 316L stainless steel powder to produce LC specimens and conducted uniaxial tensiletensile high-cycle fatigue tests to explore various laser deposition directions and surface roughnesses. The resulting SN curves provide insights into the high-cycle fatigue behaviour of LC materials. Additionally, SEM images were utilized to analyse the fatigue failure fracture characteristics. The experimental results reveal that cladding materials deposited parallel to the loading direction exhibit superior high-cycle fatigue performance. Fatigue fractures in the specimens generally originate from laser fusion defects, which not only reduce the lifespan of the specimen but also influence the failure location. Fatigue failure assessments of the laser-cladded materials were conducted via equivalent life diagrams, which revealed a high degree of correlation with the actual failure conditions. Existing fatigue design curves for base materials can be applied to the high-cycle fatigue performance design of laser-cladded 316L stainless steel, demonstrating a performance that surpasses the average level of steel butt welds.
{"title":"Experimental study on high-cycle fatigue performance of laser cladding additively manufactured 316L stainless steel","authors":"Ziyi Wang , Yue Yuan , Xiang Zhang , Bin Zeng , Chun-Lin Wang","doi":"10.1016/j.conbuildmat.2024.139214","DOIUrl":"10.1016/j.conbuildmat.2024.139214","url":null,"abstract":"<div><div>Laser cladding (LC) technology has garnered significant attention for its application in the repair of corrosion damage in steel structures. However, research on the high-cycle fatigue performance of LC materials remains limited. This study employed 316L stainless steel powder to produce LC specimens and conducted uniaxial tensile<img>tensile high-cycle fatigue tests to explore various laser deposition directions and surface roughnesses. The resulting <em>S<img>N</em> curves provide insights into the high-cycle fatigue behaviour of LC materials. Additionally, SEM images were utilized to analyse the fatigue failure fracture characteristics. The experimental results reveal that cladding materials deposited parallel to the loading direction exhibit superior high-cycle fatigue performance. Fatigue fractures in the specimens generally originate from laser fusion defects, which not only reduce the lifespan of the specimen but also influence the failure location. Fatigue failure assessments of the laser-cladded materials were conducted via equivalent life diagrams, which revealed a high degree of correlation with the actual failure conditions. Existing fatigue design curves for base materials can be applied to the high-cycle fatigue performance design of laser-cladded 316L stainless steel, demonstrating a performance that surpasses the average level of steel butt welds.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139214"},"PeriodicalIF":7.4,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663954","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}
Pub Date : 2024-11-16DOI: 10.1016/j.conbuildmat.2024.139211
Xi Yang , Zaiqiang Hu , Yi Wang , Yao Zhang , Xiaoliang Wang , Bin Hou , Yuxuan Wei , Chaochao Liu
Salinized loess exhibits poor engineering properties, including low strength, salt migration, and instability, due to the combined characteristics of loess and saline soil. This poses serious threats to the safety and stability of buildings, roads, and other infrastructure. To address this issue, this study aims to solidify salinized loess using geopolymer produced through alkali activation of industrial waste, including slag powder and fly ash. An orthogonal experimental design was used to systematically investigate the mechanical properties, microstructural characteristics, and solidification mechanism of geopolymer solidified salinized loess. The tests included unconfined compressive strength (UCS), direct shear, pH, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) to evaluate the influences of different factors on the solidification effect. The results showed that the sodium silicate solution modulus was the primary factor affecting the strength of solidified salinized loess, followed by the amounts of fly ash and slag powder. The Baumé degree (°Bé) had the least impact. Under the optimal conditions (1 modulus, 35 °Bé, slag powder and fly ash ratio of 1:0), the UCS of the sample at 28 days reached 3204.06 kPa, which increased by 16.32 times compared with the unsolidified sample. Lowering the modulus and increasing the proportion of slag powder and the Baumé degree increased the sample pH. Micro-analysis revealed that the strength increase was mainly due to the bonding of soil particles by gel substances (, , and) formed during alkali activation, as well as the filling effect of unreacted slag powder and fly ash. The findings of this study provide valuable theoretical and practical insights for treating salinized loess in engineering, offering essential references for optimizing geopolymer solidifier ratios.
{"title":"Mechanical properties and micro-mechanisms of geopolymer solidified salinized loess","authors":"Xi Yang , Zaiqiang Hu , Yi Wang , Yao Zhang , Xiaoliang Wang , Bin Hou , Yuxuan Wei , Chaochao Liu","doi":"10.1016/j.conbuildmat.2024.139211","DOIUrl":"10.1016/j.conbuildmat.2024.139211","url":null,"abstract":"<div><div>Salinized loess exhibits poor engineering properties, including low strength, salt migration, and instability, due to the combined characteristics of loess and saline soil. This poses serious threats to the safety and stability of buildings, roads, and other infrastructure. To address this issue, this study aims to solidify salinized loess using geopolymer produced through alkali activation of industrial waste, including slag powder and fly ash. An orthogonal experimental design was used to systematically investigate the mechanical properties, microstructural characteristics, and solidification mechanism of geopolymer solidified salinized loess. The tests included unconfined compressive strength (UCS), direct shear, pH, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) to evaluate the influences of different factors on the solidification effect. The results showed that the sodium silicate solution modulus was the primary factor affecting the strength of solidified salinized loess, followed by the amounts of fly ash and slag powder. The Baumé degree (°Bé) had the least impact. Under the optimal conditions (1 modulus, 35 °Bé, slag powder and fly ash ratio of 1:0), the UCS of the sample at 28 days reached 3204.06 kPa, which increased by 16.32 times compared with the unsolidified sample. Lowering the modulus and increasing the proportion of slag powder and the Baumé degree increased the sample pH. Micro-analysis revealed that the strength increase was mainly due to the bonding of soil particles by gel substances (<span><math><mrow><mi>C</mi><mo>-</mo><mi>S</mi><mo>-</mo><mi>H</mi></mrow></math></span>, <span><math><mrow><mi>N</mi><mo>-</mo><mi>A</mi><mo>-</mo><mi>S</mi><mo>-</mo><mi>H</mi></mrow></math></span>, and<span><math><mrow><mi>C</mi><mo>-</mo><mi>A</mi><mo>-</mo><mi>S</mi><mo>-</mo><mi>H</mi></mrow></math></span>) formed during alkali activation, as well as the filling effect of unreacted slag powder and fly ash. The findings of this study provide valuable theoretical and practical insights for treating salinized loess in engineering, offering essential references for optimizing geopolymer solidifier ratios.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139211"},"PeriodicalIF":7.4,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663831","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}
Pub Date : 2024-11-16DOI: 10.1016/j.conbuildmat.2024.139207
Wei Si , Qiutai Gu , Yike Yin , Xiangyu Luo , Moxuan Xia , Xin Li , Maoning Zhong , Yongping Hu
To enhance the wear resistance of traditional asphalt pavement reflective coatings and extend their cooling effect, this study employed Potassium Hexatitanate Whiskers (PHW) as a functional material to manufacture pavement reflective coatings. It was found that PHW exhibited excellent wear resistance though agglomeration resulted in adverse effects. Therefore, untreated PHW (U-PHW) underwent inorganic-organic surface modification to produce modified PHW (M-PHW). The results indicated that M-PHW exhibited excellent optical properties, with a reflectance of 78.9 %. M-PHW exhibited more uniform dispersion in the resin matrix, which significantly enhanced the coating reflectivity. Moreover, the interfacial bonding strength between M-PHW and the resin matrix was significantly improved, enhancing the wear resistance of the coating. Especially with a whisker content of 16 units, the tensile strength of the M-PHW coating reached 96.20 MPa, representing a 43.0 % increase compared to the U-PHW coating, while achieving a maximum outdoor cooling value of 5.6 °C.
{"title":"Performance optimization of novel wear-resistant reflective cooling coatings for asphalt pavement","authors":"Wei Si , Qiutai Gu , Yike Yin , Xiangyu Luo , Moxuan Xia , Xin Li , Maoning Zhong , Yongping Hu","doi":"10.1016/j.conbuildmat.2024.139207","DOIUrl":"10.1016/j.conbuildmat.2024.139207","url":null,"abstract":"<div><div>To enhance the wear resistance of traditional asphalt pavement reflective coatings and extend their cooling effect, this study employed Potassium Hexatitanate Whiskers (PHW) as a functional material to manufacture pavement reflective coatings. It was found that PHW exhibited excellent wear resistance though agglomeration resulted in adverse effects. Therefore, untreated PHW (U-PHW) underwent inorganic-organic surface modification to produce modified PHW (M-PHW). The results indicated that M-PHW exhibited excellent optical properties, with a reflectance of 78.9 %. M-PHW exhibited more uniform dispersion in the resin matrix, which significantly enhanced the coating reflectivity. Moreover, the interfacial bonding strength between M-PHW and the resin matrix was significantly improved, enhancing the wear resistance of the coating. Especially with a whisker content of 16 units, the tensile strength of the M-PHW coating reached 96.20 MPa, representing a 43.0 % increase compared to the U-PHW coating, while achieving a maximum outdoor cooling value of 5.6 °C.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139207"},"PeriodicalIF":7.4,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663772","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}
Pub Date : 2024-11-16DOI: 10.1016/j.conbuildmat.2024.139195
Jun Yang , Zhe Li , Xiaohui He , Ying Zhao , Zhicheng Sun , Ziniu Wang , Wenhui Bian
In order to study the effect of different surface protection components, such as Thin Spray-on Liner (TSL), in the support system of prestressed bolts on the critical rock mass, based on the similarity theory, physical modeling tests were designed and carried out for the support of the critical rock mass by the combination of NPR bolts and PR bolts with three types of surface protection components, such as TSL, sprayed concrete, and metal mesh, respectively. The test results show that the three types of surface protection components can significantly increase the threshold value of crack development of the critical rock specimen and effectively improve the peak bearing capacity of the critical rock body, and at the same time, the NPR bolts with higher strength and elongation have a more significant effect on the improvement of the peak bearing capacity of the critical rock specimen. In addition, TSL and spray-mixed support and specimen surface can realize close fit, in the loading of the early support response is more timely, in the late loading, compared with the spray-mixed material in the rupture of debris collapse, TSL in the occurrence of tearing can still be tightly adhered to the specimen proximity surface of the rock specimen, to prevent specimen debris fall. For the phenomenon of TSL coating rupture in the experiments, the energy balance equation was established to analyze the connection between the actual energy absorption effect and the theoretical value of the combination of TSL and bolts under the pre-stressed bolts support system, and it was found that the combination of pre-stressed bolts and TSL greatly improved the actual energy absorption effect of the support system as a whole, and the analytical results of the various experimental subgroups showed better results than the theoretical values. The analysis results of the subgroups show a good fit.
{"title":"Comparative analysis of the performance of Thin Spray-on Liner with shotcrete and mesh support","authors":"Jun Yang , Zhe Li , Xiaohui He , Ying Zhao , Zhicheng Sun , Ziniu Wang , Wenhui Bian","doi":"10.1016/j.conbuildmat.2024.139195","DOIUrl":"10.1016/j.conbuildmat.2024.139195","url":null,"abstract":"<div><div>In order to study the effect of different surface protection components, such as Thin Spray-on Liner (TSL), in the support system of prestressed bolts on the critical rock mass, based on the similarity theory, physical modeling tests were designed and carried out for the support of the critical rock mass by the combination of NPR bolts and PR bolts with three types of surface protection components, such as TSL, sprayed concrete, and metal mesh, respectively. The test results show that the three types of surface protection components can significantly increase the threshold value of crack development of the critical rock specimen and effectively improve the peak bearing capacity of the critical rock body, and at the same time, the NPR bolts with higher strength and elongation have a more significant effect on the improvement of the peak bearing capacity of the critical rock specimen. In addition, TSL and spray-mixed support and specimen surface can realize close fit, in the loading of the early support response is more timely, in the late loading, compared with the spray-mixed material in the rupture of debris collapse, TSL in the occurrence of tearing can still be tightly adhered to the specimen proximity surface of the rock specimen, to prevent specimen debris fall. For the phenomenon of TSL coating rupture in the experiments, the energy balance equation was established to analyze the connection between the actual energy absorption effect and the theoretical value of the combination of TSL and bolts under the pre-stressed bolts support system, and it was found that the combination of pre-stressed bolts and TSL greatly improved the actual energy absorption effect of the support system as a whole, and the analytical results of the various experimental subgroups showed better results than the theoretical values. The analysis results of the subgroups show a good fit.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139195"},"PeriodicalIF":7.4,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663832","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}
Pub Date : 2024-11-16DOI: 10.1016/j.conbuildmat.2024.139113
Alamgir Khan , Yingzi Yang , Shafi Ullah , Hassan Bilal , Zhichao Xu , Xiaobing Ma
Cement-based smart intrinsic composites incorporating nanocarbon-based fillers are recognized for their self-sensing abilities at ambient temperatures. However, these cement-based composites are susceptible to spalling under high-temperature conditions. Utilizing the spalling resistance of calcium aluminate cement (CAC), this study investigates the mechanical properties and piezoresistive behavior of CAC composites that incorporate multi-walled carbon nanotubes (MWCNT) and nanocarbon black (NCB) under ambient and after exposure to peak temperatures of 200°C, 400°C, and 500°C for 2 hours. The results indicate that a higher MWCNT/NCB content leads to increased compressive strength and reduced electrical resistivity. The piezoresistive performance of the composites exhibited an initial increase across CNB1 (MWCNT/NCB: 0.25/0.20 wt%), CNB2 (MWCNT/NCB: 0.50/0.40 wt%), and CNB3 (MWCNT/NCB: 0.75/0.60 wt%). However, a decline was observed in CNB4 (MWCNT/NCB: 1.0/0.80 wt%). Notably, CNB3, with its optimal concentration, demonstrated a significant enhancement in piezoresistivity, achieving a 44 % fractional change in electrical resistivity (FCR). After exposure to 200°C, the control specimen and CNB1-CNB4 exhibited peak compressive strength due to the additional hydration of anhydrous CAC and silica fume, and CNB3 reached a peak FCR of 49 %. Subsequently, after exposure to 500°C, all mixtures displayed a loss in strength; however, CNB3 and CNB4 exhibited a lower strength loss along with a slight decline in piezoresistive performance. These results highlight the potential application of CAC-based MWCNT/NCB smart intrinsic composites under extreme environmental conditions.
{"title":"Self-sensing performance of the CAC-based MWCNT/NCB composite at high temperatures","authors":"Alamgir Khan , Yingzi Yang , Shafi Ullah , Hassan Bilal , Zhichao Xu , Xiaobing Ma","doi":"10.1016/j.conbuildmat.2024.139113","DOIUrl":"10.1016/j.conbuildmat.2024.139113","url":null,"abstract":"<div><div>Cement-based smart intrinsic composites incorporating nanocarbon-based fillers are recognized for their self-sensing abilities at ambient temperatures. However, these cement-based composites are susceptible to spalling under high-temperature conditions. Utilizing the spalling resistance of calcium aluminate cement (CAC), this study investigates the mechanical properties and piezoresistive behavior of CAC composites that incorporate multi-walled carbon nanotubes (MWCNT) and nanocarbon black (NCB) under ambient and after exposure to peak temperatures of 200°C, 400°C, and 500°C for 2 hours. The results indicate that a higher MWCNT/NCB content leads to increased compressive strength and reduced electrical resistivity. The piezoresistive performance of the composites exhibited an initial increase across CNB1 (MWCNT/NCB: 0.25/0.20 wt%), CNB2 (MWCNT/NCB: 0.50/0.40 wt%), and CNB3 (MWCNT/NCB: 0.75/0.60 wt%). However, a decline was observed in CNB4 (MWCNT/NCB: 1.0/0.80 wt%). Notably, CNB3, with its optimal concentration, demonstrated a significant enhancement in piezoresistivity, achieving a 44 % fractional change in electrical resistivity (FCR). After exposure to 200°C, the control specimen and CNB1-CNB4 exhibited peak compressive strength due to the additional hydration of anhydrous CAC and silica fume, and CNB3 reached a peak FCR of 49 %. Subsequently, after exposure to 500°C, all mixtures displayed a loss in strength; however, CNB3 and CNB4 exhibited a lower strength loss along with a slight decline in piezoresistive performance. These results highlight the potential application of CAC-based MWCNT/NCB smart intrinsic composites under extreme environmental conditions.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139113"},"PeriodicalIF":7.4,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663836","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}
Pub Date : 2024-11-16DOI: 10.1016/j.conbuildmat.2024.139156
Ali Raza , Abdelatif Salmi , Mohamed Hechmi El Ouni , Nejib Ghazouani , Bilal Ahmed , Wensu Chen
The purpose of this research is to use different amounts of fly ash (FA) and ground granulated blast furnace slag (GGBS) to replace ordinary Portland cement (OPC) in polyethylene (PE) fiber-reinforced lightweight engineered geopolymers (LEGP). The mechanical characteristics and durability of these composites are examined, and the results were compared with lightweight engineered cementitious composites (LECC). Expanded glass aggregates were used to produce lightweight LEGP and LECC composites. The composites were exposed to a 5 % solution for up to 180 days. The performance of LEGP and LECC specimens under normal and sulfate environments was assessed using a variety of tests and analyses, including evaluations of relative slump, density, compressive stress-strain behavior, flexural strength, load-deflection response, split tensile strength, ultrasonic pulse velocity, initial surface absorption, mass change, and mercury intrusion porosimetry (MIP). Microstructural and mineralogical analysis of the composite matrix was conducted using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) were employed to evaluate the thermal stability of the composites. The results showed that in both normal and sulfate conditions, LEGP specimens with 100 % GGBS showed higher residual compressive, flexural, and split tensile strengths while having minimum initial surface absorption and mass loss as compared with LECC specimens. MIP analysis showed that LEGP mixes with 100 % FA exhibited a more notable increase in pore volume under sulfate exposure leading to reduced performance. LECC specimens subjected to 5 % solution showed peaks of quartz, mullite, portlandite, and ettringite at higher intensities with calcite and nepheline minerals at lower intensities, while LEGP samples subjected to 5 % solution were characterized by the formation of quartz, mullite, portlandite, calcite, zeolite, gypsum, and ettringite peaks. FTIR and DTG results showed that and were transformed into gypsum and mullite after a sulfate attack for 180 days.
{"title":"Material characterization and thermal performance of polyethylene fiber-reinforced lightweight engineered geopolymer composites subjected to sulfate attacks","authors":"Ali Raza , Abdelatif Salmi , Mohamed Hechmi El Ouni , Nejib Ghazouani , Bilal Ahmed , Wensu Chen","doi":"10.1016/j.conbuildmat.2024.139156","DOIUrl":"10.1016/j.conbuildmat.2024.139156","url":null,"abstract":"<div><div>The purpose of this research is to use different amounts of fly ash (FA) and ground granulated blast furnace slag (GGBS) to replace ordinary Portland cement (OPC) in polyethylene (PE) fiber-reinforced lightweight engineered geopolymers (LEGP). The mechanical characteristics and durability of these composites are examined, and the results were compared with lightweight engineered cementitious composites (LECC). Expanded glass aggregates were used to produce lightweight LEGP and LECC composites. The composites were exposed to a 5 % <span><math><mrow><mi>N</mi><msub><mrow><mi>a</mi></mrow><mrow><mn>2</mn></mrow></msub><mi>S</mi><msub><mrow><mi>O</mi></mrow><mrow><mn>4</mn></mrow></msub></mrow></math></span> solution for up to 180 days. The performance of LEGP and LECC specimens under normal and sulfate environments was assessed using a variety of tests and analyses, including evaluations of relative slump, density, compressive stress-strain behavior, flexural strength, load-deflection response, split tensile strength, ultrasonic pulse velocity, initial surface absorption, mass change, and mercury intrusion porosimetry (MIP). Microstructural and mineralogical analysis of the composite matrix was conducted using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) were employed to evaluate the thermal stability of the composites. The results showed that in both normal and sulfate conditions, LEGP specimens with 100 % GGBS showed higher residual compressive, flexural, and split tensile strengths while having minimum initial surface absorption and mass loss as compared with LECC specimens. MIP analysis showed that LEGP mixes with 100 % FA exhibited a more notable increase in pore volume under sulfate exposure leading to reduced performance. LECC specimens subjected to 5 % <span><math><mrow><mi>N</mi><msub><mrow><mi>a</mi></mrow><mrow><mn>2</mn></mrow></msub><mi>S</mi><msub><mrow><mi>O</mi></mrow><mrow><mn>4</mn></mrow></msub></mrow></math></span> solution showed peaks of quartz, mullite, portlandite, and ettringite at higher intensities with calcite and nepheline minerals at lower intensities, while LEGP samples subjected to 5 % <span><math><mrow><mi>N</mi><msub><mrow><mi>a</mi></mrow><mrow><mn>2</mn></mrow></msub><mi>S</mi><msub><mrow><mi>O</mi></mrow><mrow><mn>4</mn></mrow></msub></mrow></math></span> solution were characterized by the formation of quartz, mullite, portlandite, calcite, zeolite, gypsum, and ettringite peaks. FTIR and DTG results showed that <span><math><mrow><mi>C</mi><mo>−</mo><mi>S</mi><mo>−</mo><mi>H</mi></mrow></math></span> and <span><math><mrow><mi>Ca</mi><msub><mrow><mo>(</mo><mi>OH</mi><mo>)</mo></mrow><mrow><mn>2</mn></mrow></msub></mrow></math></span> were transformed into gypsum and mullite after a sulfate attack for 180 days.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139156"},"PeriodicalIF":7.4,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663835","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}
Pub Date : 2024-11-16DOI: 10.1016/j.conbuildmat.2024.139126
Peng Zhao , Gang Xu , Qing Wang , Zhen Zeng
The stray current generated during the operation of rail transit projects located in coastal and saline soil areas often makes the concrete structures along the line in a deteriorating environment with the coexistence of chloride salt and stray current, which significantly accelerates the corrosion process of steel bars and endangers the safety of engineering structures. In this paper, the depassivation behavior and corrosion behavior of steel bars in simulated pore solution under the combined action of low DC stray current and chloride ion were studied by electrochemical method. The results show that when the DC stray current and chloride ion coexist, the steel bar is easy to depassivate, and the two promote each other, the coupling effect is obvious. At a constant chloride ion concentration, the pH, chloride ion concentration of the corrosive medium and current density will affect the corrosion current efficiency. In the high pH environment, the current efficiency gradually increases with the increase of chloride ion concentration, but as the pH decreases or the chloride ion concentration continues to increase, the current efficiency is slightly greater than 1.0. When the concentration of chloride ions is inconsistent, the higher the concentration of chloride ions in a local area, the more severe the corrosion of the rebar in that area. The difference in resistance between the steel bar and the cathode caused by the concentration difference of chloride ions is the main reason for the different electricity consumption in each region and the overall uneven corrosion.
{"title":"Corrosion behavior of steel bars in simulated concrete pore solution under the coupling action of chloride salt and DC stray current","authors":"Peng Zhao , Gang Xu , Qing Wang , Zhen Zeng","doi":"10.1016/j.conbuildmat.2024.139126","DOIUrl":"10.1016/j.conbuildmat.2024.139126","url":null,"abstract":"<div><div>The stray current generated during the operation of rail transit projects located in coastal and saline soil areas often makes the concrete structures along the line in a deteriorating environment with the coexistence of chloride salt and stray current, which significantly accelerates the corrosion process of steel bars and endangers the safety of engineering structures. In this paper, the depassivation behavior and corrosion behavior of steel bars in simulated pore solution under the combined action of low DC stray current and chloride ion were studied by electrochemical method. The results show that when the DC stray current and chloride ion coexist, the steel bar is easy to depassivate, and the two promote each other, the coupling effect is obvious. At a constant chloride ion concentration, the pH, chloride ion concentration of the corrosive medium and current density will affect the corrosion current efficiency. In the high pH environment, the current efficiency gradually increases with the increase of chloride ion concentration, but as the pH decreases or the chloride ion concentration continues to increase, the current efficiency is slightly greater than 1.0. When the concentration of chloride ions is inconsistent, the higher the concentration of chloride ions in a local area, the more severe the corrosion of the rebar in that area. The difference in resistance between the steel bar and the cathode caused by the concentration difference of chloride ions is the main reason for the different electricity consumption in each region and the overall uneven corrosion.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139126"},"PeriodicalIF":7.4,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663837","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}
Pub Date : 2024-11-15DOI: 10.1016/j.conbuildmat.2024.139208
Xueqi Wang , Mulian Zheng , Chenxu Gong , Hongyin Li , Sai Ma , Jinghan Xu
Composite seal (CS) is effective in restoring pavement surface function and prolonging the service life, employing a double-layer structure composed of micro-surfacing and chip seal. Rejuvenating composite seal (RCS) applying rejuvenating agents to the chip seal is dedicated to revitalizing the aged asphalt of the original pavement surface. However, limited studies have focused on enhancing interlayer and temperature performance through optimizing mixture ratios. In this study, a modified emulsified asphalt with self-developed rejuvenating agent was applied, and the orthogonal test considering interlayer shear resistance and high temperature stability was conducted for initially mixture proportion of RCS, then the preliminary ratio was optimized. The proportion for micro-surfacing was determined by mixing test, wet track abrasion test, and loaded wheel sticking sand test. Simultaneously, the recommended asphalt spraying amount of rejuvenating chip seal was determined by utilizing accelerated loading abrasion test. In view of the abrasion resistance, interlayer adhesion, and cracking resistance, the coupled effects of aggregate size and paving rate of rejuvenating chip seal were studied. Long-term wet track abrasion test, freeze-thaw cycle test, and UV aging test were conducted to evaluate the durability. The results show that the asphalt-aggregate ratio of micro-surfacing is 7.1 %. For 4.75 mm or 7 mm rejuvenating chip seal, the recommended asphalt spraying amount is 1.5 kg/m2 or 1.6 kg/m2, and the range of paving rate is 60 %–70 %. For 9.5 mm or 13.2 mm rejuvenating chip seal, the results are 1.7 kg/m2 or 1.8 kg/m2, and 80 %–90 %, respectively. Under the conditions, RCS has better interlayer shear resistance and temperature performance, which can improve durability.
{"title":"Mixture proportion optimization and durability evaluation of rejuvenating composite seal","authors":"Xueqi Wang , Mulian Zheng , Chenxu Gong , Hongyin Li , Sai Ma , Jinghan Xu","doi":"10.1016/j.conbuildmat.2024.139208","DOIUrl":"10.1016/j.conbuildmat.2024.139208","url":null,"abstract":"<div><div>Composite seal (CS) is effective in restoring pavement surface function and prolonging the service life, employing a double-layer structure composed of micro-surfacing and chip seal. Rejuvenating composite seal (RCS) applying rejuvenating agents to the chip seal is dedicated to revitalizing the aged asphalt of the original pavement surface. However, limited studies have focused on enhancing interlayer and temperature performance through optimizing mixture ratios. In this study, a modified emulsified asphalt with self-developed rejuvenating agent was applied, and the orthogonal test considering interlayer shear resistance and high temperature stability was conducted for initially mixture proportion of RCS, then the preliminary ratio was optimized. The proportion for micro-surfacing was determined by mixing test, wet track abrasion test, and loaded wheel sticking sand test. Simultaneously, the recommended asphalt spraying amount of rejuvenating chip seal was determined by utilizing accelerated loading abrasion test. In view of the abrasion resistance, interlayer adhesion, and cracking resistance, the coupled effects of aggregate size and paving rate of rejuvenating chip seal were studied. Long-term wet track abrasion test, freeze-thaw cycle test, and UV aging test were conducted to evaluate the durability. The results show that the asphalt-aggregate ratio of micro-surfacing is 7.1 %. For 4.75 mm or 7 mm rejuvenating chip seal, the recommended asphalt spraying amount is 1.5 kg/m<sup>2</sup> or 1.6 kg/m<sup>2</sup>, and the range of paving rate is 60 %–70 %. For 9.5 mm or 13.2 mm rejuvenating chip seal, the results are 1.7 kg/m<sup>2</sup> or 1.8 kg/m<sup>2</sup>, and 80 %–90 %, respectively. Under the conditions, RCS has better interlayer shear resistance and temperature performance, which can improve durability.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139208"},"PeriodicalIF":7.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664253","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}
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