Pub Date : 2024-10-10DOI: 10.1016/j.cemconcomp.2024.105796
Nicolas Maamary, Ibrahim G. Ogunsanya
Chloride-induced corrosion of steel reinforcing bar (rebar) is the primary cause of deterioration in reinforced concrete structures, posing a significant infrastructure challenge. The chloride threshold level (CTL) of rebar, which represents the critical amount of chloride needed to initiate active corrosion, is crucial in corrosion and service life prediction models. However, substantial uncertainties and a multitude of influencing factors, along with the absence of a universally accepted testing framework, hinder the achievement of a consistent CTL range for service life models and complicate comparisons of published values. This study addresses these challenges by developing multiple machine learning models to predict CTL, considering 21 carefully selected features. A comprehensive database of 423 data points was compiled from an exhaustive literature review. Seven machine learning models—linear regression, decision tree, random forest, K-nearest neighbors, support vector machine, artificial neural network, and an ensemble model—were developed and optimized. The ensemble model achieved superior prediction performance, with a mean absolute error of 0.218% by weight of binder, root mean square error of 0.321%, and a coefficient of determination of 0.751 on unseen CTL data. Partial dependence plots generated using the support vector machine model quantified the effect of each feature on CTL. The random forest model identified SiO₂ binder content and exposed rebar area to chlorides as the most influential factors. The study also examined the impact of supplementary cementitious materials (SCMs), finding that only blast furnace slag positively affected CTL.
{"title":"Exploring Machine Learning to Study and Predict the Chloride Threshold Level for Carbon Steel Reinforcement","authors":"Nicolas Maamary, Ibrahim G. Ogunsanya","doi":"10.1016/j.cemconcomp.2024.105796","DOIUrl":"10.1016/j.cemconcomp.2024.105796","url":null,"abstract":"<div><div>Chloride-induced corrosion of steel reinforcing bar (rebar) is the primary cause of deterioration in reinforced concrete structures, posing a significant infrastructure challenge. The chloride threshold level (CTL) of rebar, which represents the critical amount of chloride needed to initiate active corrosion, is crucial in corrosion and service life prediction models. However, substantial uncertainties and a multitude of influencing factors, along with the absence of a universally accepted testing framework, hinder the achievement of a consistent CTL range for service life models and complicate comparisons of published values. This study addresses these challenges by developing multiple machine learning models to predict CTL, considering 21 carefully selected features. A comprehensive database of 423 data points was compiled from an exhaustive literature review. Seven machine learning models—linear regression, decision tree, random forest, K-nearest neighbors, support vector machine, artificial neural network, and an ensemble model—were developed and optimized. The ensemble model achieved superior prediction performance, with a mean absolute error of 0.218% by weight of binder, root mean square error of 0.321%, and a coefficient of determination of 0.751 on unseen CTL data. Partial dependence plots generated using the support vector machine model quantified the effect of each feature on CTL. The random forest model identified SiO₂ binder content and exposed rebar area to chlorides as the most influential factors. The study also examined the impact of supplementary cementitious materials (SCMs), finding that only blast furnace slag positively affected CTL.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105796"},"PeriodicalIF":10.8,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142405358","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}
Pub Date : 2024-10-10DOI: 10.1016/j.cemconcomp.2024.105795
Fabian B. Rodriguez , Reza Moini , Shubham Agrawal , Christopher S. Williams , Pablo D. Zavattieri , Jan Olek , Jeffrey P. Youngblood , Amit H. Varma
This paper presents the mechanical properties of composite beams additively manufactured by 3D-printing of layers of mortar on top of custom-designed (also 3D-printed) steel plates, which served as external flexural reinforcement. The mechanical performance of the composite beams was evaluated using three-point bending test. The results were compared with the data obtained from two types of reference specimens: 3D-printed beams with no external reinforcing plate, and composite beams with mortar cast (rather than 3D printed) on the top of the steel plate. Four different architectures (also referred to as configurations) were created by either 3D-printing (using two different filament orientations), casting, or a combination of both processes (referred to as a hybrid configuration). This configuration consisted of 3D-printed external walls (outline) of the beam and cast interior (infill). The effects of these architectures were investigated using both unreinforced and composite elements, in order to identify the contributions of the orientation of filaments and associated interfaces on the initiation and propagation of the cracks. Analysis of the initiation and propagation of the cracks was based on the data obtained from the digital image correlation (DIC) technique. Mechanical performance parameters that were investigated included the following: load-displacement responses, flexural stress-flexural strain responses, shear stress-shear strain responses, and the work of failure. The results of the test revealed that the incorporation of steel plates as an external reinforcement resulted in the transition from flexural to shear mode failure. In terms of flexural strength, all composite configurations demonstrated comparable performance independently of the architecture used while hybrid configuration outperformed cast composite counterparts by attaining significantly higher values of the work of failure. This indicates that hybrid elements developed enhanced energy dissipation characteristics compared to the other configurations. The results of specific modulus of rupture and shear strength obtained from unreinforced and reinforced hybrid elements, respectively, were comparable to those obtained from cast counterparts, indicating that the hybrid configuration may offer a viable alternative for the construction of structural concrete elements. Finally, the values of modulus of rupture and shear stress obtained for different configurations used in the study were compared to the design expressions in the ACI 318–19 code. It was found that hybrid elements as well as cast elements used in this study satisfy the minimum requirements and further studies at larger scales could confirm their use in structural applications.
本文介绍了通过三维打印技术在定制设计（也是三维打印）的钢板（用作外部抗弯加固）上添加砂浆层而制造的复合梁的力学性能。采用三点弯曲试验对复合梁的机械性能进行了评估。测试结果与两种参考试样的数据进行了比较：一种是没有外部加固板的 3D 打印梁，另一种是在钢板顶部浇注砂浆（而不是 3D 打印）的复合梁。通过三维打印（使用两种不同的长丝方向）、浇注或两种工艺的组合（称为混合配置），创建了四种不同的结构（也称为配置）。这种结构包括三维打印的梁外壁（轮廓）和铸造的内壁（填充）。我们使用非加固元件和复合元件对这些结构的影响进行了研究，以确定细丝的取向和相关界面对裂纹的产生和扩展所起的作用。根据数字图像相关（DIC）技术获得的数据对裂纹的产生和扩展进行了分析。研究的机械性能参数包括：载荷-位移响应、挠曲应力-挠曲应变响应、剪切应力-剪切应变响应和破坏功。试验结果表明，钢板作为外部加固材料的加入导致了从弯曲模式到剪切模式的失效。在抗弯强度方面，所有复合材料配置都表现出了相当的性能，与所使用的结构无关，而混合配置的性能则优于铸造复合材料，其破坏功值明显更高。这表明，与其他配置相比，混合元件具有更强的消能特性。非加固混合构件和加固混合构件分别获得的比断裂模量和剪切强度结果与浇注混合构件获得的结果相当，这表明混合构件可为混凝土结构构件的建造提供一种可行的替代方案。最后，将研究中使用的不同配置所获得的断裂模量和剪应力值与 ACI 318-19 规范中的设计表达式进行了比较。结果发现，本研究中使用的混合构件和浇注构件都能满足最低要求，而更大规模的进一步研究可以证实它们在结构应用中的用途。
{"title":"Mechanical response of small-scale 3D-printed steel-mortar composite beams","authors":"Fabian B. Rodriguez , Reza Moini , Shubham Agrawal , Christopher S. Williams , Pablo D. Zavattieri , Jan Olek , Jeffrey P. Youngblood , Amit H. Varma","doi":"10.1016/j.cemconcomp.2024.105795","DOIUrl":"10.1016/j.cemconcomp.2024.105795","url":null,"abstract":"<div><div>This paper presents the mechanical properties of composite beams additively manufactured by 3D-printing of layers of mortar on top of custom-designed (also 3D-printed) steel plates, which served as external flexural reinforcement. The mechanical performance of the composite beams was evaluated using three-point bending test. The results were compared with the data obtained from two types of reference specimens: 3D-printed beams with no external reinforcing plate, and composite beams with mortar cast (rather than 3D printed) on the top of the steel plate. Four different architectures (also referred to as <em>configurations</em>) were created by either 3D-printing (using two different filament orientations), casting, or a combination of both processes (referred to as a <em>hybrid</em> configuration). This configuration consisted of 3D-printed external walls (outline) of the beam and cast interior (infill). The effects of these architectures were investigated using both unreinforced and composite elements, in order to identify the contributions of the orientation of filaments and associated interfaces on the initiation and propagation of the cracks. Analysis of the initiation and propagation of the cracks was based on the data obtained from the digital image correlation (DIC) technique. Mechanical performance parameters that were investigated included the following: load-displacement responses, flexural stress-flexural strain responses, shear stress-shear strain responses, and the work of failure. The results of the test revealed that the incorporation of steel plates as an external reinforcement resulted in the transition from flexural to shear mode failure. In terms of flexural strength, all composite configurations demonstrated comparable performance independently of the architecture used while hybrid configuration outperformed cast composite counterparts by attaining significantly higher values of the work of failure. This indicates that hybrid elements developed enhanced energy dissipation characteristics compared to the other configurations. The results of specific modulus of rupture and shear strength obtained from unreinforced and reinforced hybrid elements, respectively, were comparable to those obtained from cast counterparts, indicating that the hybrid configuration may offer a viable alternative for the construction of structural concrete elements. Finally, the values of modulus of rupture and shear stress obtained for different configurations used in the study were compared to the design expressions in the ACI 318–19 code. It was found that hybrid elements as well as cast elements used in this study satisfy the minimum requirements and further studies at larger scales could confirm their use in structural applications.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105795"},"PeriodicalIF":10.8,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142397926","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 : 2024-10-10DOI: 10.1016/j.cemconcomp.2024.105793
Hua Jiang , Dongyang Tian , Minghao Dong , Maorong Lv , Xiaocong Yang , Shuang Lu
Developing novel, environmentally friendly, and efficient corrosion inhibitors is of great significance for improving the durability of marine concrete against chloride ion erosion. This paper aims to explore the potential of layered double hydroxides (LDHs) as nanocontainers, incorporating organic corrosion inhibitors between LDHs layers to synergistically enhance their effectiveness. In this study, Mg/Al-pAB-LDH was synthesized through the interlayer modification of LDHs with an organic corrosion inhibitor, p-aminobenzoic acid (pAB), employing a calcination-rehydration method. Chloride ion (Cl−) adsorption behavior was quantitatively and qualitatively analyzed and the effect on mortar properties was investigated. The corrosion resistance of steel bars in the mortar was assessed under chloride salt simulated concrete pore solution (SCPs) and chloride salt wet-dry cycles via electrochemical tests and microscopic characterization of Mg/Al-pAB-LDH. The results demonstrate that Mg/Al-pAB-LDH efficiently captures Cl− and releases corrosion-inhibiting ions pAB, with the adsorption process conforming to pseudo-second-order kinetics and Langmuir adsorption isotherm. Mg/Al-pAB-LDH enhances the pore structure of mortar, effectively improving mechanical properties and resistance to chloride ion penetration, with the optimal effect observed at a 4 % addition rate. Mg/Al-pAB-LDH demonstrates outstanding corrosion resistance to steel bars in both SCPs and mortar. In SCPs, it serves as a corrosion inhibitor by adsorbing Cl− and releasing pAB, whereas in mortar, it functions as a corrosion inhibitor by enhancing the physical barrier effect of mortar, adsorbing Cl−, and releasing pAB. This study demonstrates the promising potential of utilizing Mg/Al-pAB-LDH as a novel corrosion inhibitor to mitigate the corrosion of steel bars in marine concrete.
{"title":"Effects of interlayer-modified layered double hydroxides with organic corrosion inhibiting ions on the properties of cement-based materials and reinforcement corrosion in chloride environment","authors":"Hua Jiang , Dongyang Tian , Minghao Dong , Maorong Lv , Xiaocong Yang , Shuang Lu","doi":"10.1016/j.cemconcomp.2024.105793","DOIUrl":"10.1016/j.cemconcomp.2024.105793","url":null,"abstract":"<div><div>Developing novel, environmentally friendly, and efficient corrosion inhibitors is of great significance for improving the durability of marine concrete against chloride ion erosion. This paper aims to explore the potential of layered double hydroxides (LDHs) as nanocontainers, incorporating organic corrosion inhibitors between LDHs layers to synergistically enhance their effectiveness. In this study, Mg/Al-pAB-LDH was synthesized through the interlayer modification of LDHs with an organic corrosion inhibitor, p-aminobenzoic acid (pAB), employing a calcination-rehydration method. Chloride ion (Cl<sup>−</sup>) adsorption behavior was quantitatively and qualitatively analyzed and the effect on mortar properties was investigated. The corrosion resistance of steel bars in the mortar was assessed under chloride salt simulated concrete pore solution (SCPs) and chloride salt wet-dry cycles via electrochemical tests and microscopic characterization of Mg/Al-pAB-LDH. The results demonstrate that Mg/Al-pAB-LDH efficiently captures Cl<sup>−</sup> and releases corrosion-inhibiting ions pAB, with the adsorption process conforming to pseudo-second-order kinetics and Langmuir adsorption isotherm. Mg/Al-pAB-LDH enhances the pore structure of mortar, effectively improving mechanical properties and resistance to chloride ion penetration, with the optimal effect observed at a 4 % addition rate. Mg/Al-pAB-LDH demonstrates outstanding corrosion resistance to steel bars in both SCPs and mortar. In SCPs, it serves as a corrosion inhibitor by adsorbing Cl<sup>−</sup> and releasing pAB, whereas in mortar, it functions as a corrosion inhibitor by enhancing the physical barrier effect of mortar, adsorbing Cl<sup>−</sup>, and releasing pAB. This study demonstrates the promising potential of utilizing Mg/Al-pAB-LDH as a novel corrosion inhibitor to mitigate the corrosion of steel bars in marine concrete.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105793"},"PeriodicalIF":10.8,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142398330","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 : 2024-10-08DOI: 10.1016/j.cemconcomp.2024.105792
Yingjie Li , Xiaohui Zeng , Binbin Yin , Jilin Wang , K.M. Liew
Cement-based materials (CBM) in humid environments, influenced by their inherent defects and the presence of pore solution, exhibit poor electrical insulation performance. Low electrical resistivity of cement-based materials poses a threat to the safety of resilient infrastructures, shortens the lifespan of materials, and increases the costs of maintenance and repair. In this work, we first elucidate two primary mechanisms for enhancing electrical resistivity: (1) inhibition of ion electromigration and (2) disruption of conduction paths. We then systematically summarize and discuss 16 potential methods for improving their electrical resistivity based on these mechanisms. It is indicated that among these 16 methods, early carbonation curing, the addition of high-activity mineral admixtures, and surface hydrophobic modification are particularly effective approaches. The combination of two or more methods can simultaneously exert their functions, thus maximizing the overall effectiveness. Future work is outlined with the aim of meeting the growing demand for cement-based materials with high electrical resistivity in the construction of resilient infrastructures.
{"title":"Electrical resistivity of cement-based materials through ion conduction mechanisms for enhancing resilient infrastructures","authors":"Yingjie Li , Xiaohui Zeng , Binbin Yin , Jilin Wang , K.M. Liew","doi":"10.1016/j.cemconcomp.2024.105792","DOIUrl":"10.1016/j.cemconcomp.2024.105792","url":null,"abstract":"<div><div>Cement-based materials (CBM) in humid environments, influenced by their inherent defects and the presence of pore solution, exhibit poor electrical insulation performance. Low electrical resistivity of cement-based materials poses a threat to the safety of resilient infrastructures, shortens the lifespan of materials, and increases the costs of maintenance and repair. In this work, we first elucidate two primary mechanisms for enhancing electrical resistivity: (1) inhibition of ion electromigration and (2) disruption of conduction paths. We then systematically summarize and discuss 16 potential methods for improving their electrical resistivity based on these mechanisms. It is indicated that among these 16 methods, early carbonation curing, the addition of high-activity mineral admixtures, and surface hydrophobic modification are particularly effective approaches. The combination of two or more methods can simultaneously exert their functions, thus maximizing the overall effectiveness. Future work is outlined with the aim of meeting the growing demand for cement-based materials with high electrical resistivity in the construction of resilient infrastructures.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105792"},"PeriodicalIF":10.8,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142384966","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 : 2024-10-05DOI: 10.1016/j.cemconcomp.2024.105788
Kesheng Yin , Peiliang Shen , Limin Zhang , Yamei Cai , Dongxing Xuan , Chi Sun Poon
Seawater cement slurry (SCS) is a commonly used binder in offshore deep cement mixing (DCM) construction. Seawater cement slurries are usually prepared before they are grouted into the seabed and mixed with marine clay. The aim of this study is to explore the feasibility of applying carbonation technology to fabricate SCS suitable for offshore DCM while achieving carbon sequestration and obtaining better mechanical properties for stabilised marine sediments.
This study demonstrated that after appropriate carbonation, carbonized SCS can be used in DCM to replace conventional SCS. Short-term carbonation promotes cement dissolution and hydration rates under seawater conditions rich in magnesium, calcium, and other inorganic ions. The carbonates include calcite, vaterite and amorphous carbonates, which provide additional nucleation sites for the hydration of SCS, resulting in an increment for amorphous CS(A)H gel with a dense pore structure and binding interaction with soil particles. After carbonation with 20 % CO2 for 5 min (0.5 wt% of cement), the UCS and secant modulus of cement-soil mixtures by 15.7 % and 111 % at the age of 1 day, and by 6.82 % and 10 % at the age of 28 days when treating marine clay with 80 % moisture content at a dosage of 260 kg/m3.
{"title":"Carbonized seawater cement slurries for offshore deep cement mixing: Carbonation mechanism, strength enhancement and microstructure evolution","authors":"Kesheng Yin , Peiliang Shen , Limin Zhang , Yamei Cai , Dongxing Xuan , Chi Sun Poon","doi":"10.1016/j.cemconcomp.2024.105788","DOIUrl":"10.1016/j.cemconcomp.2024.105788","url":null,"abstract":"<div><div>Seawater cement slurry (SCS) is a commonly used binder in offshore deep cement mixing (DCM) construction. Seawater cement slurries are usually prepared before they are grouted into the seabed and mixed with marine clay. The aim of this study is to explore the feasibility of applying carbonation technology to fabricate SCS suitable for offshore DCM while achieving carbon sequestration and obtaining better mechanical properties for stabilised marine sediments.</div><div>This study demonstrated that after appropriate carbonation, carbonized SCS can be used in DCM to replace conventional SCS. Short-term carbonation promotes cement dissolution and hydration rates under seawater conditions rich in magnesium, calcium, and other inorganic ions. The carbonates include calcite, vaterite and amorphous carbonates, which provide additional nucleation sites for the hydration of SCS, resulting in an increment for amorphous CS(A)H gel with a dense pore structure and binding interaction with soil particles. After carbonation with 20 % CO2 for 5 min (0.5 wt% of cement), the UCS and secant modulus of cement-soil mixtures by 15.7 % and 111 % at the age of 1 day, and by 6.82 % and 10 % at the age of 28 days when treating marine clay with 80 % moisture content at a dosage of 260 kg/m<sup>3</sup>.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105788"},"PeriodicalIF":10.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142377461","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 : 2024-10-04DOI: 10.1016/j.cemconcomp.2024.105787
Chathuranga Balasooriya Arachchilage, Guangping Huang, Jian Zhao, Chengkai Fan, Wei Victor Liu
The design of cementitious mixtures incorporating mine tailings as fine aggregates is a multi-objective optimization (MOO) problem, in which both the uniaxial compressive strength (UCS) and cost of the mixtures need to be considered simultaneously. Given that data-driven methods have shown promising results when solving similar MOO problems, this study developed an extreme gradient boosting regressor (XGBR) model on a dataset extracted from the literature to predict the UCS. Among the efforts taken to improve the models, a genetic algorithm (GA)-based XGBR model demonstrated the optimal prediction performance, with an R2 of 0.959. Next, the GA-XGBR model and a cost equation were used as objective functions in the MOO problem. The non-dominated sorting genetic algorithm with elite strategy (NSGA-II) was selected to solve the optimization problem. A case study was conducted, generating mixture designs that offered improved trade-offs between cost and UCS compared to experimental designs. Finally, a graphical user interface was developed to provide access to the prediction model and optimization method. Overall, this work can be used as a guide for optimal mixture designs as it facilitates informed decision-making before the actual applications.
{"title":"Hybrid extreme gradient boosting regressor models for the multi-objective mixture design optimization of cementitious mixtures incorporating mine tailings as fine aggregates","authors":"Chathuranga Balasooriya Arachchilage, Guangping Huang, Jian Zhao, Chengkai Fan, Wei Victor Liu","doi":"10.1016/j.cemconcomp.2024.105787","DOIUrl":"10.1016/j.cemconcomp.2024.105787","url":null,"abstract":"<div><div>The design of cementitious mixtures incorporating mine tailings as fine aggregates is a multi-objective optimization (MOO) problem, in which both the uniaxial compressive strength (UCS) and cost of the mixtures need to be considered simultaneously. Given that data-driven methods have shown promising results when solving similar MOO problems, this study developed an extreme gradient boosting regressor (XGBR) model on a dataset extracted from the literature to predict the UCS. Among the efforts taken to improve the models, a genetic algorithm (GA)-based XGBR model demonstrated the optimal prediction performance, with an R<sup>2</sup> of 0.959. Next, the GA-XGBR model and a cost equation were used as objective functions in the MOO problem. The non-dominated sorting genetic algorithm with elite strategy (NSGA-II) was selected to solve the optimization problem. A case study was conducted, generating mixture designs that offered improved trade-offs between cost and UCS compared to experimental designs. Finally, a graphical user interface was developed to provide access to the prediction model and optimization method. Overall, this work can be used as a guide for optimal mixture designs as it facilitates informed decision-making before the actual applications.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105787"},"PeriodicalIF":10.8,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142370070","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}
Pub Date : 2024-10-04DOI: 10.1016/j.cemconcomp.2024.105789
Hyunuk Kang , Jingwei Yang , Junil Pae , Seohyun Kim , Sung-Hoon Kang , Juhyuk Moon
Glycol-based components are commonly used as grinding agents in ordinary Portland cement (OPC). However, their effects on the grindability and hydration mechanism have not been fully understood. In this study, the effects of mono-ethylene glycol (MEG) of various concentrations (0, 0.025, and 0.05 %) on OPC grinding characteristics as well as hydration reaction were examined. The use of MEG improved the grinding performance of OPC powder, and this effect became more noticeable with increasing quantities of MEG. Moreover, the addition of MEG substantial influenced the hydration properties of the OPC. Although there was no substantial difference in the reactivity of the aluminate phases, the reactivity of the silicate phases improved at all stages. This effect intensified with increasing concentrations of MEG. Additionally, the amount of calcium carbonate increased with the addition of MEG, indicating that MEG somehow promotes carbonation as well. With all these effects, it was concluded that the MEG proportionally enhanced the mechanical performance.
乙二醇基成分通常用作普通硅酸盐水泥（OPC）的研磨剂。然而，它们对可磨性和水化机理的影响尚未得到充分了解。本研究考察了不同浓度（0、0.025 和 0.05%）的单乙二醇（MEG）对 OPC 粉磨特性和水化反应的影响。MEG 的使用改善了 OPC 粉末的研磨性能，随着 MEG 用量的增加，这种效果更加明显。此外，添加 MEG 对 OPC 的水合特性也有很大影响。虽然铝酸盐相的反应性没有本质区别，但硅酸盐相的反应性在各个阶段都有所改善。这种影响随着 MEG 浓度的增加而增强。此外，碳酸钙的数量随着 MEG 的添加而增加，这表明 MEG 也在某种程度上促进了碳化。综上所述，可以得出结论：MEG 按比例提高了机械性能。
{"title":"The impact of mono-ethylene glycol on ordinary Portland cement: Exploring grindability, workability, hydration, and mechanical properties","authors":"Hyunuk Kang , Jingwei Yang , Junil Pae , Seohyun Kim , Sung-Hoon Kang , Juhyuk Moon","doi":"10.1016/j.cemconcomp.2024.105789","DOIUrl":"10.1016/j.cemconcomp.2024.105789","url":null,"abstract":"<div><div>Glycol-based components are commonly used as grinding agents in ordinary Portland cement (OPC). However, their effects on the grindability and hydration mechanism have not been fully understood. In this study, the effects of mono-ethylene glycol (MEG) of various concentrations (0, 0.025, and 0.05 %) on OPC grinding characteristics as well as hydration reaction were examined. The use of MEG improved the grinding performance of OPC powder, and this effect became more noticeable with increasing quantities of MEG. Moreover, the addition of MEG substantial influenced the hydration properties of the OPC. Although there was no substantial difference in the reactivity of the aluminate phases, the reactivity of the silicate phases improved at all stages. This effect intensified with increasing concentrations of MEG. Additionally, the amount of calcium carbonate increased with the addition of MEG, indicating that MEG somehow promotes carbonation as well. With all these effects, it was concluded that the MEG proportionally enhanced the mechanical performance.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105789"},"PeriodicalIF":10.8,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142370072","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}
This paper introduces a theoretical model for forecasting fiber orientation in 3D-printed ultra-high-performance concrete (3DP-UHPC). Initially, the dynamic evolution process of fiber alignment in 3DP-UHPC was characterized using X-ray computed tomography (X-CT) and image analysis. The results indicated that fiber alignment during extrusion process was primarily constrained by the rigid boundary of nozzle. Leveraging stereology theory, the regularity of fiber alignment affected by boundary effects was elucidated. Following layer deposition, the flattening effect resulting from the nozzle's extrusion force and gravity of upper layers influenced fiber alignment along printing direction. To quantify this impact, a flattening correction coefficient was introduced to modify fiber orientation coefficient in an ideal state. Finally, considering the overlapping effect of boundary and flattening on fiber orientation in 3DP-UHPC, a theoretical model was developed to predict fiber orientation. The model demonstrated robust adaptability, providing valuable insights into the design of 3DP-UHPC with improved fiber reinforcement efficiency.
本文介绍了预测三维打印超高性能混凝土（3DP-UHPC）中纤维取向的理论模型。首先，利用 X 射线计算机断层扫描（X-CT）和图像分析表征了 3DP-UHPC 中纤维排列的动态演变过程。结果表明，挤压过程中的纤维排列主要受到喷嘴刚性边界的限制。利用立体学理论，阐明了纤维排列受边界效应影响的规律性。层沉积后，喷嘴挤出力和上层重力产生的扁平效应影响了纤维沿印刷方向的排列。为了量化这种影响，引入了扁平化修正系数来修正理想状态下的纤维取向系数。最后，考虑到边界和扁平化对 3DP-UHPC 中纤维取向的重叠影响，建立了一个理论模型来预测纤维取向。该模型具有强大的适应性，为设计具有更高纤维增强效率的 3DP-UHPC 提供了宝贵的见解。
{"title":"Modeling fiber alignment in 3D printed ultra-high-performance concrete based on stereology theory","authors":"Enlai Dong , Zijian Jia , Lutao Jia , Suduan Rao , Xudong Zhao , Rui Yu , Zedi Zhang , Yueyi Gao , Wei Wang , Yamei Zhang , Yu Chen , Nemkumar Banthia","doi":"10.1016/j.cemconcomp.2024.105786","DOIUrl":"10.1016/j.cemconcomp.2024.105786","url":null,"abstract":"<div><div>This paper introduces a theoretical model for forecasting fiber orientation in 3D-printed ultra-high-performance concrete (3DP-UHPC). Initially, the dynamic evolution process of fiber alignment in 3DP-UHPC was characterized using X-ray computed tomography (X-CT) and image analysis. The results indicated that fiber alignment during extrusion process was primarily constrained by the rigid boundary of nozzle. Leveraging stereology theory, the regularity of fiber alignment affected by boundary effects was elucidated. Following layer deposition, the flattening effect resulting from the nozzle's extrusion force and gravity of upper layers influenced fiber alignment along printing direction. To quantify this impact, a flattening correction coefficient was introduced to modify fiber orientation coefficient in an ideal state. Finally, considering the overlapping effect of boundary and flattening on fiber orientation in 3DP-UHPC, a theoretical model was developed to predict fiber orientation. The model demonstrated robust adaptability, providing valuable insights into the design of 3DP-UHPC with improved fiber reinforcement efficiency.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105786"},"PeriodicalIF":10.8,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142370069","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 : 2024-10-03DOI: 10.1016/j.cemconcomp.2024.105790
Atolo A. Tuinukuafe , David X. Rademacher , Tina M. Nenoff , Jessica M. Rimsza
Pozzolans rich in silica and alumina react with lime to form cementing compounds and are incorporated into portland cement as supplementary cementitious materials (SCMs). However, pozzolanic reactions progress slower than portland cement hydration, limiting their use in modern construction due to insufficient early-age strength. Hence, alternative SCMs that enable faster pozzolanic reactions are necessary including synthetic zeolites, which have high surface areas and compositional purity that indicate the possibility of rapid pozzolanic reactivity. Synthetic zeolites with varying cation composition (Na-zeolite, H-zeolite), SiO2/Al2O3 ratio, and framework type were evaluated for pozzolanic reactivity via Ca(OH)2 consumption using ion exchange and in-situ X-ray diffraction experiments. Na-zeolites exhibited limited exchange reactions with KOH and Ca(OH)2 due to the occupancy of acid sites by Na+ and hydroxyl groups. Meanwhile, H-zeolites readily adsorbed K+ and Ca2+ from a hydroxide solution by exchanging cations with H+ at Brønsted acid sites or cation adsorption at vacant acid sites. By adsorbing cations, the H-zeolite reduced the pH and increased Ca2+ solubility to promote pozzolanic reactions in a system where Ca(OH)2 dissolution/diffusion was a rate limiting factor. High H-zeolite reactivity resulted in 0.8 g of Ca(OH)2 consumed per 1 g of zeolites after 16 h of reaction versus 0.4 g of Ca(OH)2 consumed per 1 g of Na-zeolite. The H-zeolite modulated the pore fluid alkalinity and created a low-density amorphous silicate phase via mechanisms analogous to two-step C-S-H nucleation experiments. Controlling these reaction mechanisms is key to developing next generation pozzolanic cementitious systems with comparable hydration rates to portland cement.
{"title":"Enhanced pozzolanic reactivity in hydrogen-form zeolites as supplementary cementitious materials","authors":"Atolo A. Tuinukuafe , David X. Rademacher , Tina M. Nenoff , Jessica M. Rimsza","doi":"10.1016/j.cemconcomp.2024.105790","DOIUrl":"10.1016/j.cemconcomp.2024.105790","url":null,"abstract":"<div><div>Pozzolans rich in silica and alumina react with lime to form cementing compounds and are incorporated into portland cement as supplementary cementitious materials (SCMs). However, pozzolanic reactions progress slower than portland cement hydration, limiting their use in modern construction due to insufficient early-age strength. Hence, alternative SCMs that enable faster pozzolanic reactions are necessary including synthetic zeolites, which have high surface areas and compositional purity that indicate the possibility of rapid pozzolanic reactivity. Synthetic zeolites with varying cation composition (Na-zeolite, H-zeolite), SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> ratio, and framework type were evaluated for pozzolanic reactivity via Ca(OH)<sub>2</sub> consumption using ion exchange and in-situ X-ray diffraction experiments. Na-zeolites exhibited limited exchange reactions with KOH and Ca(OH)<sub>2</sub> due to the occupancy of acid sites by Na<sup>+</sup> and hydroxyl groups. Meanwhile, H-zeolites readily adsorbed K<sup>+</sup> and Ca<sup>2+</sup> from a hydroxide solution by exchanging cations with H<sup>+</sup> at Brønsted acid sites or cation adsorption at vacant acid sites. By adsorbing cations, the H-zeolite reduced the pH and increased Ca<sup>2+</sup> solubility to promote pozzolanic reactions in a system where Ca(OH)<sub>2</sub> dissolution/diffusion was a rate limiting factor. High H-zeolite reactivity resulted in 0.8 g of Ca(OH)<sub>2</sub> consumed per 1 g of zeolites after 16 h of reaction versus 0.4 g of Ca(OH)<sub>2</sub> consumed per 1 g of Na-zeolite. The H-zeolite modulated the pore fluid alkalinity and created a low-density amorphous silicate phase via mechanisms analogous to two-step C-S-H nucleation experiments. Controlling these reaction mechanisms is key to developing next generation pozzolanic cementitious systems with comparable hydration rates to portland cement.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105790"},"PeriodicalIF":10.8,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142370073","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 : 2024-10-02DOI: 10.1016/j.cemconcomp.2024.105784
Chunxiang Qian , Yilin Su , Qingbo Liu , Yaya Yuan
Microbial self-healing technology for concrete is attracting widespread attention due to its environmentally friendly, non-toxic, and sustainable attributes. Currently, microbial agents utilized in concrete exhibit a high dependence on atmospheric conditions, relying on atmospheric oxygen to activate or capture carbon dioxide from the air for the generation of carbonate ions. This paper introduces an innovative low-dependency microbial restorative aimed at augmenting the self-healing capability of concrete by nearly doubling the available carbonate ions and providing 80 % of them internally, especially targeting deep cracks. A pioneering approach was employed by combining microorganisms that rapidly produce carbon dioxide with those that expedite carbon dioxide hydration. Microbial functional components were meticulously pelletized to create core-shell structure restorative particles, featuring an outer protective layer constructed with low-alkali cement. This study investigates the mechanism through simulation and experimentation, including substrate conversion, carbon dioxide transformation, and the generation and accumulation of carbonate ions and calcium ions. Essentially, this research not only presents a path towards reduced atmospheric dependence but also provides valuable insights for comprehending the mechanism behind microbial self-healing concrete.
{"title":"Self-healing of cracks in cement-based materials through bio-mineralization of low air-dependency microorganisms","authors":"Chunxiang Qian , Yilin Su , Qingbo Liu , Yaya Yuan","doi":"10.1016/j.cemconcomp.2024.105784","DOIUrl":"10.1016/j.cemconcomp.2024.105784","url":null,"abstract":"<div><div>Microbial self-healing technology for concrete is attracting widespread attention due to its environmentally friendly, non-toxic, and sustainable attributes. Currently, microbial agents utilized in concrete exhibit a high dependence on atmospheric conditions, relying on atmospheric oxygen to activate or capture carbon dioxide from the air for the generation of carbonate ions. This paper introduces an innovative low-dependency microbial restorative aimed at augmenting the self-healing capability of concrete by nearly doubling the available carbonate ions and providing 80 % of them internally, especially targeting deep cracks. A pioneering approach was employed by combining microorganisms that rapidly produce carbon dioxide with those that expedite carbon dioxide hydration. Microbial functional components were meticulously pelletized to create core-shell structure restorative particles, featuring an outer protective layer constructed with low-alkali cement. This study investigates the mechanism through simulation and experimentation, including substrate conversion, carbon dioxide transformation, and the generation and accumulation of carbonate ions and calcium ions. Essentially, this research not only presents a path towards reduced atmospheric dependence but also provides valuable insights for comprehending the mechanism behind microbial self-healing concrete.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105784"},"PeriodicalIF":10.8,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142370075","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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