Cement & concrete composites最新文献_第5页

Novel high-efficiency solid particle foam stabilizer: Effects of modified fly ash on foam properties and foam concrete 新型高效固体颗粒泡沫稳定剂：改性粉煤灰对泡沫性能和泡沫混凝土的影响

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

Cement & concrete composites

Pub Date : 2024-10-24 DOI: 10.1016/j.cemconcomp.2024.105818

Qiang Song , Yingjie Zou , Peng Zhang , Shipeng Xu , Yuxin Yang , Jiuwen Bao , Shanbin Xue , Jie Liu , Shujun Gao , Liang Lin

The preparation of foam concrete frequently encounters challenges such as foam collapse and stratification, which lead to a decline in material performance. Therefore, enhancing foam stability is paramount in the production of foam concrete. This study innovatively addresses this issue by investigating the use of waste fly ash particles (RFA) and modified fly ash (AMFA, BMFA, and CMFA) as foam stabilizers, and comparing their efficacy with that of traditional nano-silica stabilizers (NS), both independently and in combination. The results indicate that modified ultrafine fly ash particles (AMFA) exhibit foam stability properties (1-h settlement distance and bleeding rate) comparable to those of NS. Moreover, when combined with NS, the mixture surpasses the foam performance of NS alone. Utilizing these highly stable foams, lightweight foam concrete with a 600 kg/m³ density is produced, demonstrating exceptional mechanical properties (compressive strength of 3.42 MPa) and superior thermal insulation (thermal conductivity of 0.0914 W/m· K). The enhanced foam stability of the modified fly ash is primarily attributed to increased surface roughness, hydrogen bonding, and van der Waals forces. Developing highly stable foams holds significant potential, contributing to energy conservation, emissions reduction, and waste management.

泡沫混凝土的制备经常会遇到泡沫坍塌和分层等难题，从而导致材料性能下降。因此，在泡沫混凝土生产过程中，提高泡沫稳定性至关重要。本研究创新性地解决了这一问题，研究了使用废弃粉煤灰颗粒（RFA）和改性粉煤灰（AMFA、BMFA 和 CMFA）作为泡沫稳定剂，并比较了它们与传统纳米二氧化硅稳定剂（NS）单独或组合使用时的功效。结果表明，改性超细粉煤灰颗粒（AMFA）的泡沫稳定性能（1 小时沉降距离和渗流率）与 NS 相当。此外，当与 NS 混合使用时，混合物的泡沫性能超过了单独使用 NS 时的性能。利用这些高度稳定的泡沫，可生产出密度为 600 kg/m³ 的轻质泡沫混凝土，并显示出优异的机械性能（抗压强度为 3.42 MPa）和卓越的隔热性能（导热系数为 0.0914 W/ m-K）。改性粉煤灰泡沫稳定性的增强主要归功于表面粗糙度、氢键和范德华力的增加。开发高度稳定的泡沫具有巨大潜力，有助于节能、减排和废物管理。

{"title":"Novel high-efficiency solid particle foam stabilizer: Effects of modified fly ash on foam properties and foam concrete","authors":"Qiang Song , Yingjie Zou , Peng Zhang , Shipeng Xu , Yuxin Yang , Jiuwen Bao , Shanbin Xue , Jie Liu , Shujun Gao , Liang Lin","doi":"10.1016/j.cemconcomp.2024.105818","DOIUrl":"10.1016/j.cemconcomp.2024.105818","url":null,"abstract":"<div><div>The preparation of foam concrete frequently encounters challenges such as foam collapse and stratification, which lead to a decline in material performance. Therefore, enhancing foam stability is paramount in the production of foam concrete. This study innovatively addresses this issue by investigating the use of waste fly ash particles (RFA) and modified fly ash (AMFA, BMFA, and CMFA) as foam stabilizers, and comparing their efficacy with that of traditional nano-silica stabilizers (NS), both independently and in combination. The results indicate that modified ultrafine fly ash particles (AMFA) exhibit foam stability properties (1-h settlement distance and bleeding rate) comparable to those of NS. Moreover, when combined with NS, the mixture surpasses the foam performance of NS alone. Utilizing these highly stable foams, lightweight foam concrete with a 600 kg/m³ density is produced, demonstrating exceptional mechanical properties (compressive strength of 3.42 MPa) and superior thermal insulation (thermal conductivity of 0.0914 W/m· K). The enhanced foam stability of the modified fly ash is primarily attributed to increased surface roughness, hydrogen bonding, and van der Waals forces. Developing highly stable foams holds significant potential, contributing to energy conservation, emissions reduction, and waste management.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"155 ","pages":"Article 105818"},"PeriodicalIF":10.8,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142489215","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

Sustainable and mechanical properties of Engineered Cementitious Composites with biochar: Integrating micro- and macro-mechanical insight 含生物炭的工程水泥基复合材料的可持续性和力学性能：综合微观和宏观力学观点

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

Cement & concrete composites

Pub Date : 2024-10-24 DOI: 10.1016/j.cemconcomp.2024.105813

Tianyu Wang , Yihong Tang , Shaofeng Qin , Gang Li , Haoliang Wu , Christopher K.Y. Leung

Engineered Cementitious Composites (ECC) are ductile, strain-hardening cementitious composites with a tightly controlled crack opening profile. A significant concern in the development and application of ECC is its high carbon emissions associated with high cement content consumption. As an emerging green additive, biochar can significantly cut down on the carbon emission of concrete products. However, research that integrates micro- and macro-mechanical insights with biochar incorporation is limited. In this study, micro-mechanical tools indicated that a certain amount of substitution biochar could enhance the tensile properties of ECC. The study assessed various properties including compressive strength, porosity, density, tensile performance, crack pattern, sustainability and cost of ECC with different biochar proportions. The findings showed that incorporating 10 %–20 % biochar effectively increased the tensile strain capacity and decreased the crack opening width in ECC materials. This improvement can be attributed to the introduction of finer biochar particles (≤75 μm) at the fiber/matrix interfacial transition zone, which alters the fiber-bridging force by reducing the chemical and frictional bond strength between the fiber and matrix, as revealed by micro-mechanical tests and microstructural inspection. Moreover, the utilization of biochar contributes to reducing the carbon emission of ECC, enhancing sustainability while maintaining a ∼10 % minimal reduction in compressive strength. Overall, this study introduces a novel approach for reusing low-carbon biomass waste in the production of building materials, offering potential advantages in micro- and macro-mechanical performance, cost-effectiveness, and environmental sustainability.

工程水泥基复合材料（ECC）是一种韧性好、应变硬化的水泥基复合材料，具有严格控制的裂缝张开曲线。在开发和应用 ECC 的过程中，一个重要的问题是其与高水泥含量消耗相关的高碳排放量。作为一种新兴的绿色添加剂，生物炭可以大大减少混凝土产品的碳排放量。然而，将微观和宏观力学观点与生物炭掺合结合起来的研究还很有限。在这项研究中，微观力学工具表明，一定量的替代生物炭可以提高 ECC 的拉伸性能。研究评估了不同生物炭比例的 ECC 的各种性能，包括抗压强度、孔隙率、密度、拉伸性能、裂纹模式、可持续性和成本。研究结果表明，加入 10% 到 20% 的生物炭可有效提高 ECC 材料的拉伸应变能力，并减少裂缝开口宽度。这种改善可归因于在纤维/基体界面过渡区引入了更细的生物炭颗粒（≤75μm），从而通过降低纤维与基体之间的化学和摩擦结合强度来改变纤维桥接力。此外，生物炭的使用有助于减少 ECC 的碳排放，在保持抗压强度降低 10% 左右的同时提高可持续性。总之，本研究介绍了一种在建筑材料生产中再利用低碳生物质废物的新方法，在微观和宏观机械性能、成本效益和环境可持续性方面具有潜在优势。

{"title":"Sustainable and mechanical properties of Engineered Cementitious Composites with biochar: Integrating micro- and macro-mechanical insight","authors":"Tianyu Wang , Yihong Tang , Shaofeng Qin , Gang Li , Haoliang Wu , Christopher K.Y. Leung","doi":"10.1016/j.cemconcomp.2024.105813","DOIUrl":"10.1016/j.cemconcomp.2024.105813","url":null,"abstract":"<div><div>Engineered Cementitious Composites (ECC) are ductile, strain-hardening cementitious composites with a tightly controlled crack opening profile. A significant concern in the development and application of ECC is its high carbon emissions associated with high cement content consumption. As an emerging green additive, biochar can significantly cut down on the carbon emission of concrete products. However, research that integrates micro- and macro-mechanical insights with biochar incorporation is limited. In this study, micro-mechanical tools indicated that a certain amount of substitution biochar could enhance the tensile properties of ECC. The study assessed various properties including compressive strength, porosity, density, tensile performance, crack pattern, sustainability and cost of ECC with different biochar proportions. The findings showed that incorporating 10 %–20 % biochar effectively increased the tensile strain capacity and decreased the crack opening width in ECC materials. This improvement can be attributed to the introduction of finer biochar particles (≤75 μm) at the fiber/matrix interfacial transition zone, which alters the fiber-bridging force by reducing the chemical and frictional bond strength between the fiber and matrix, as revealed by micro-mechanical tests and microstructural inspection. Moreover, the utilization of biochar contributes to reducing the carbon emission of ECC, enhancing sustainability while maintaining a ∼10 % minimal reduction in compressive strength. Overall, this study introduces a novel approach for reusing low-carbon biomass waste in the production of building materials, offering potential advantages in micro- and macro-mechanical performance, cost-effectiveness, and environmental sustainability.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"155 ","pages":"Article 105813"},"PeriodicalIF":10.8,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488119","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

Enhancement in clinker hydration degrees and later stage-ettringite stability of calcium sulfoaluminate cements by the incorporation of dolomite 通过掺入白云石提高硫铝酸钙水泥的熟料水化度和后期铁素体稳定性

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

Cement & concrete composites

Pub Date : 2024-10-23 DOI: 10.1016/j.cemconcomp.2024.105815

Naru Kim , Joonho Seo , H.K. Lee

The hydration degrees of clinkers and ettringite stability in calcium sulfoaluminate (C

\overline{S}

A) cements in the presence of externally supplied dolomite were investigated in this study. The mineralogical and microstructural characteristics of C

\overline{S}

A cements containing different dosages of dolomite were characterized using X-ray diffractometry, Rietveld refinement-based quantification analysis, thermogravimetry analysis, mercury intrusion porosimetry, scanning electron microscopy observation, and energy dispersive spectroscopy point analysis. Furthermore, the binder systems were simulated using thermodynamic modeling to observe the phase changes of hydration products and the underlying hydration kinetics. The incorporation of dolomite accelerated clinker consumption and enhanced the stability of ettringite throughout the testing period, due possibly to the nucleation seeding effect and provision of carbonate ions by dolomite. The modeling outcomes showed the stability of ettringite at later stage by the incorporation of dolomite in the simulated timeframe, yet the active dissolution of dolomite assumed in the modeling procedure overestimated the Mg-bearing hydrates in the samples.

本研究调查了在外部供应白云石的情况下，硫铝酸钙（C A）水泥中熟料的水化程度和蚀变石的稳定性。采用 X 射线衍射仪、基于 Rietveld 精炼的定量分析、热重分析、汞侵入孔隙度测定法、扫描电子显微镜观察和能量色散光谱点分析，对含有不同剂量白云石的 C A 水泥的矿物学和微观结构特征进行了表征。此外，还利用热力学模型模拟了粘合剂系统，以观察水合产物的相变和基本的水合动力学。在整个测试期间，白云石的加入加速了熟料的消耗，并增强了乙丁橡胶的稳定性，这可能是由于白云石的成核种子效应和碳酸根离子的提供。建模结果表明，在模拟时间范围内掺入白云石后，乙长石在后期具有稳定性，但建模过程中假设的白云石主动溶解高估了样品中的含镁水合物。

{"title":"Enhancement in clinker hydration degrees and later stage-ettringite stability of calcium sulfoaluminate cements by the incorporation of dolomite","authors":"Naru Kim , Joonho Seo , H.K. Lee","doi":"10.1016/j.cemconcomp.2024.105815","DOIUrl":"10.1016/j.cemconcomp.2024.105815","url":null,"abstract":"<div><div>The hydration degrees of clinkers and ettringite stability in calcium sulfoaluminate (C <span><math><mrow><mover><mi>S</mi><mo>‾</mo></mover></mrow></math></span> A) cements in the presence of externally supplied dolomite were investigated in this study. The mineralogical and microstructural characteristics of C <span><math><mrow><mover><mi>S</mi><mo>‾</mo></mover></mrow></math></span> A cements containing different dosages of dolomite were characterized using X-ray diffractometry, Rietveld refinement-based quantification analysis, thermogravimetry analysis, mercury intrusion porosimetry, scanning electron microscopy observation, and energy dispersive spectroscopy point analysis. Furthermore, the binder systems were simulated using thermodynamic modeling to observe the phase changes of hydration products and the underlying hydration kinetics. The incorporation of dolomite accelerated clinker consumption and enhanced the stability of ettringite throughout the testing period, due possibly to the nucleation seeding effect and provision of carbonate ions by dolomite. The modeling outcomes showed the stability of ettringite at later stage by the incorporation of dolomite in the simulated timeframe, yet the active dissolution of dolomite assumed in the modeling procedure overestimated the Mg-bearing hydrates in the samples.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"155 ","pages":"Article 105815"},"PeriodicalIF":10.8,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488111","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

Bond and cracking behavior of tailored limestone calcined clay cement-based composites including bicomponent polypropylene fibers with enhanced mechanical interlocking 包括双组分聚丙烯纤维的定制石灰石煅烧粘土水泥基复合材料的粘结和开裂行为，具有更强的机械互锁性

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

Cement & concrete composites

Pub Date : 2024-10-23 DOI: 10.1016/j.cemconcomp.2024.105812

Mihaela-Monica Popa , Cesare Signorini , Mirza A.B. Beigh , Ahmad Chihadeh , Markus Stommel , Michael Kaliske , Viktor Mechtcherine , Christina Scheffler

This study examines the potential of combining tailored binder formulations with engineered polypropylene (PP) fibers to develop a range of Fiber-Reinforced Cementitious (FRC) systems with enhanced ductility and strain-hardening properties, while encompassing sustainability and economic viability. The experimental investigation compares the surface microstructure of novel bicomponent PP fibers, produced using a pilot fiber spinning device, with that of standard PP fibers. Micro-scale single-fiber pull-out tests are conducted to ascertain the extent to which this surface modification contributes to enhanced energy absorption. The effectiveness of these novel fibers at the composite scale is assessed when embedded into two limestone calcined clay cement (LC³) binder systems, in terms of the fresh and hardened properties of the resulting FRLC³, with low cement content (35 % of the total binder). The effect of incorporating super absorbent polymer (SAP) on tailoring the internal porosity of the matrix, thereby promoting the potential for stress transfer via multiple crack pathways, is assessed. A Finite Element Method (FEM) analysis, calibrated with the materials and bond laws retrieved experimentally, is conducted to simulate the tensile and cracking behavior of the optimal material combination investigated in this study, demonstrating a high degree of correlation with the tensile tests.

本研究探讨了将定制粘结剂配方与工程聚丙烯（PP）纤维相结合，开发一系列具有更强延展性和应变硬化特性的纤维增强水泥基（FRC）系统的潜力，同时兼顾可持续性和经济可行性。实验研究比较了使用试验纤维纺丝装置生产的新型双组分聚丙烯纤维与标准聚丙烯纤维的表面微观结构。进行了微尺度单纤维拉出试验，以确定这种表面改性在多大程度上有助于增强能量吸收。在将这些新型纤维嵌入两种石灰石煅烧粘土水泥（LC3）粘结剂体系时，对其在复合材料中的有效性进行了评估，评估结果显示，在水泥含量较低（占粘结剂总量的 35%）的情况下，FRLC3 的新鲜和硬化性能都很好。评估了加入超强吸水聚合物（SAP）对调整基质内部孔隙率的影响，从而提高了通过多种裂缝途径进行应力传递的可能性。通过有限元法（FEM）分析，并根据实验中获得的材料和粘结规律进行校准，模拟了本研究中最佳材料组合的拉伸和开裂行为，结果表明与拉伸试验高度相关。

{"title":"Bond and cracking behavior of tailored limestone calcined clay cement-based composites including bicomponent polypropylene fibers with enhanced mechanical interlocking","authors":"Mihaela-Monica Popa , Cesare Signorini , Mirza A.B. Beigh , Ahmad Chihadeh , Markus Stommel , Michael Kaliske , Viktor Mechtcherine , Christina Scheffler","doi":"10.1016/j.cemconcomp.2024.105812","DOIUrl":"10.1016/j.cemconcomp.2024.105812","url":null,"abstract":"<div><div>This study examines the potential of combining tailored binder formulations with engineered polypropylene (PP) fibers to develop a range of Fiber-Reinforced Cementitious (FRC) systems with enhanced ductility and strain-hardening properties, while encompassing sustainability and economic viability. The experimental investigation compares the surface microstructure of novel bicomponent PP fibers, produced using a pilot fiber spinning device, with that of standard PP fibers. Micro-scale single-fiber pull-out tests are conducted to ascertain the extent to which this surface modification contributes to enhanced energy absorption. The effectiveness of these novel fibers at the composite scale is assessed when embedded into two limestone calcined clay cement (LC<sup>3</sup>) binder systems, in terms of the fresh and hardened properties of the resulting FRLC<sup>3</sup>, with low cement content (35 % of the total binder). The effect of incorporating super absorbent polymer (SAP) on tailoring the internal porosity of the matrix, thereby promoting the potential for stress transfer via multiple crack pathways, is assessed. A Finite Element Method (FEM) analysis, calibrated with the materials and bond laws retrieved experimentally, is conducted to simulate the tensile and cracking behavior of the optimal material combination investigated in this study, demonstrating a high degree of correlation with the tensile tests.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"155 ","pages":"Article 105812"},"PeriodicalIF":10.8,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142487464","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

Mechanisms of efflorescence of alkali-activated slag 碱激活炉渣的风化机理

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

Cement & concrete composites

Pub Date : 2024-10-23 DOI: 10.1016/j.cemconcomp.2024.105811

Chen Liu , Zhenming Li , Guang Ye

Efflorescence presents not only as a cosmetic concern but also as a structural issue, which impacts the performance of alkali-activated materials (AAMs). In this study, the mechanisms of efflorescence of alkali-activated slag (AAS) pastes are investigated. First, the efflorescence of AAS pastes with different alkali dosages (3 %, 5 % and 7 %), activator types (sodium hydroxide (NH) and sodium silicate (NS)), exposure atmospheres (ambient, N₂ and 0.2 vol% CO₂), and relative humidities (40 %, 60 % and 80 %) was observed. Subsequently, leaching tests were performed and the impacts of efflorescence on AAS pastes at different heights were studied. It was found that a lower relative humidity facilitated more rapid and severe efflorescence. The positioning of efflorescence products was dependent on the porosity of the matrix. Compared to NH pastes, NS pastes subjected to semi-contact water conditions were more vulnerable to cracking problems, which turned out to be exacerbated by the formation of efflorescence products. A new method to quantify efflorescence was developed and it corresponded well with both efflorescence observations and leaching experiments. Furthermore, a competitive reaction between Ca and Na in the presence of carbonate ions was identified. CaCO₃, a representative product of natural carbonation, was rarely found in the regions where efflorescence products (sodium carbonate) formed. Regarding compressive strength, NS pastes were more adversely affected by efflorescence than NH pastes.

风化不仅是一个外观问题，也是一个结构问题，会影响碱活性材料（AAM）的性能。本研究探讨了碱活性矿渣（AAS）浆料的风化机理。首先，观察了不同碱用量（3%、5% 和 7%）、活化剂类型（氢氧化钠 (NH) 和硅酸钠 (NS)）、暴露气氛（环境、N2 和 0.2 vol.% CO2）和相对湿度（40%、60% 和 80%）下 AAS 浆料的风化现象。随后，进行了沥滤试验，并研究了不同高度的渗出对 AAS 浆料的影响。结果发现，相对湿度越低，风化越快、越严重。风化产物的位置取决于基质的孔隙率。与 NH 浆料相比，在半接触水条件下的 NS 浆料更容易出现开裂问题，而这些问题又会因风化产物的形成而加剧。研究人员开发了一种量化风化的新方法，该方法与风化观察和浸出实验结果十分吻合。此外，还确定了 Ca 和 Na 在碳酸根离子存在下的竞争反应。在形成风化产物（碳酸钠）的区域很少发现 CaCO3，而 CaCO3 是自然碳化的代表性产物。在抗压强度方面，NS 浆料比 NH 浆料更容易受到风化的不利影响。

{"title":"Mechanisms of efflorescence of alkali-activated slag","authors":"Chen Liu , Zhenming Li , Guang Ye","doi":"10.1016/j.cemconcomp.2024.105811","DOIUrl":"10.1016/j.cemconcomp.2024.105811","url":null,"abstract":"<div><div>Efflorescence presents not only as a cosmetic concern but also as a structural issue, which impacts the performance of alkali-activated materials (AAMs). In this study, the mechanisms of efflorescence of alkali-activated slag (AAS) pastes are investigated. First, the efflorescence of AAS pastes with different alkali dosages (3 %, 5 % and 7 %), activator types (sodium hydroxide (NH) and sodium silicate (NS)), exposure atmospheres (ambient, N<sub>2</sub> and 0.2 vol% CO<sub>2</sub>), and relative humidities (40 %, 60 % and 80 %) was observed. Subsequently, leaching tests were performed and the impacts of efflorescence on AAS pastes at different heights were studied. It was found that a lower relative humidity facilitated more rapid and severe efflorescence. The positioning of efflorescence products was dependent on the porosity of the matrix. Compared to NH pastes, NS pastes subjected to semi-contact water conditions were more vulnerable to cracking problems, which turned out to be exacerbated by the formation of efflorescence products. A new method to quantify efflorescence was developed and it corresponded well with both efflorescence observations and leaching experiments. Furthermore, a competitive reaction between Ca and Na in the presence of carbonate ions was identified. CaCO<sub>3</sub>, a representative product of natural carbonation, was rarely found in the regions where efflorescence products (sodium carbonate) formed. Regarding compressive strength, NS pastes were more adversely affected by efflorescence than NH pastes.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"155 ","pages":"Article 105811"},"PeriodicalIF":10.8,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142487064","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

Exploring the potential of construction-compatible materials in structural supercapacitors for energy storage in the built environment 探索建筑兼容材料在建筑环境结构超级电容器储能方面的潜力

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

Cement & concrete composites

Pub Date : 2024-10-21 DOI: 10.1016/j.cemconcomp.2024.105809

Arslan Yousaf, Shoukat Alim Khan, Muammer Koç

As urbanization accelerates, the need for innovative solutions that integrate energy storage within the built environment (BE) becomes increasingly vital for sustainable and multifunctional infrastructure. This review paper delves into the pioneering concept of structural supercapacitors (SSCs), which seamlessly embed energy storage capabilities directly into construction materials such as ordinary portland cement, geopolymers, magnesium phosphate cement, aluminate cement, bricks, wood, and polymers. These materials are readily available and possess inherent structural strength, making them ideal candidates for functionalization as energy storage devices. SSCs rely on the combination of mechanical strength and electrochemical capabilities, allowing structures to serve dual functions—bearing mechanical loads while storing and releasing electrical energy. This review discusses the key components of SSCs, including conductive fillers, electrodes, and electrolytes, and evaluates their electrochemical and mechanical performance. Several critical research gaps have been identified, including the need for alternative conductive fillers to improve ionic conductivity and specific capacitance, advanced additives to enhance multifunctionality and optimization of the interaction between fillers and substrates. Additionally, post-curing treatments and the control of porosity and microstructure require further exploration to balance electrochemical performance with mechanical robustness. Challenges related to integrating SSCs into practical applications, such as environmental durability and mechanical load-bearing capacity, are also highlighted. Furthermore, the potential of 3D printing technology to create customizable SSC structures is identified as a promising area for future research. This review contributes to advancing SSCs and their potential integration into sustainable infrastructure by highlighting the gaps and future directions of the existing literature.

随着城市化进程的加快，在建筑环境（BE）中集成储能的创新解决方案对于可持续和多功能基础设施的需求变得越来越重要。本综述论文深入探讨了结构超级电容器（SSC）这一开创性概念，它将储能功能直接无缝嵌入普通硅酸盐水泥、土工聚合物、磷酸镁水泥、铝酸盐水泥、砖块、木材和聚合物等建筑材料中。这些材料随处可得，并具有固有的结构强度，是功能化为储能装置的理想候选材料。SSC 依靠机械强度和电化学能力的结合，使结构具有双重功能--承受机械负荷，同时存储和释放电能。本综述讨论了 SSC 的关键成分，包括导电填料、电极和电解质，并评估了它们的电化学和机械性能。研究发现了几个关键的研究空白，包括需要替代导电填料来提高离子导电性和比电容，需要先进的添加剂来增强多功能性，以及需要优化填料和基底之间的相互作用。此外，还需要进一步探索后固化处理以及孔隙率和微观结构的控制，以平衡电化学性能和机械坚固性。此外，还强调了与将 SSCs 集成到实际应用中有关的挑战，如环境耐久性和机械承载能力。此外，三维打印技术在创建可定制的 SSC 结构方面的潜力也被认为是未来研究的一个前景广阔的领域。本综述强调了现有文献中存在的不足和未来的研究方向，从而有助于推动南南合作及其与可持续基础设施的潜在结合。

{"title":"Exploring the potential of construction-compatible materials in structural supercapacitors for energy storage in the built environment","authors":"Arslan Yousaf, Shoukat Alim Khan, Muammer Koç","doi":"10.1016/j.cemconcomp.2024.105809","DOIUrl":"10.1016/j.cemconcomp.2024.105809","url":null,"abstract":"<div><div>As urbanization accelerates, the need for innovative solutions that integrate energy storage within the built environment (BE) becomes increasingly vital for sustainable and multifunctional infrastructure. This review paper delves into the pioneering concept of structural supercapacitors (SSCs), which seamlessly embed energy storage capabilities directly into construction materials such as ordinary portland cement, geopolymers, magnesium phosphate cement, aluminate cement, bricks, wood, and polymers. These materials are readily available and possess inherent structural strength, making them ideal candidates for functionalization as energy storage devices. SSCs rely on the combination of mechanical strength and electrochemical capabilities, allowing structures to serve dual functions—bearing mechanical loads while storing and releasing electrical energy. This review discusses the key components of SSCs, including conductive fillers, electrodes, and electrolytes, and evaluates their electrochemical and mechanical performance. Several critical research gaps have been identified, including the need for alternative conductive fillers to improve ionic conductivity and specific capacitance, advanced additives to enhance multifunctionality and optimization of the interaction between fillers and substrates. Additionally, post-curing treatments and the control of porosity and microstructure require further exploration to balance electrochemical performance with mechanical robustness. Challenges related to integrating SSCs into practical applications, such as environmental durability and mechanical load-bearing capacity, are also highlighted. Furthermore, the potential of 3D printing technology to create customizable SSC structures is identified as a promising area for future research. This review contributes to advancing SSCs and their potential integration into sustainable infrastructure by highlighting the gaps and future directions of the existing literature.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"155 ","pages":"Article 105809"},"PeriodicalIF":10.8,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142452634","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

The effect of water absorption and specific gravity of supplementary cementitious materials on required water 辅助胶凝材料的吸水性和比重对所需水量的影响

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

Cement & concrete composites

Pub Date : 2024-10-19 DOI: 10.1016/j.cemconcomp.2024.105808

Krishna Siva Teja Chopperla , Gopakumar Kaladaran , Anna K. Kochaver , O. Burkan Isgor , W. Jason Weiss

The use of supplementary cementitious materials (SCM) is projected to increase because they reduce the global warming potential of concrete. When cement is replaced with SCM, the flow of the mixture may change. The porosity of the paste may also change as the liquid-to-solid volumes change when mass replacement is used. This paper discusses the role of water absorption and the specific gravity of the SCM on the water requirements of a mixture. Over thirty SCMs were tested, including sixteen natural pozzolans, ten coal ashes, three blended pozzolans, and one ground glass. The porosity of the SCM was measured using a drying rate test. The water absorbed by the natural pozzolans ranged from 3.25 to 17.25 %, 5.55–9.25 % for blended pozzolans, 4.10–18.95 % for coal ashes, and 4.20 % for ground glass. The water requirement measured using ASTM C311 ranged from −4.25 to 46.2 %. The specific gravity of the SCM is particularly important when it is significantly different from the specific gravity of the OPC, as this can change the liquid-to-solid volume ratio. Accounting for the absorption of water by the SCM and the specific gravity of the SCM (via volume replacement) resulted in 55 % of the specimens having a water demand within ±5 % of the original mixture to achieve the same flow, and 94 % of the samples had a water demand within ±20 %. This was substantially less than mass replacement. Using volume replacement and accounting for SCM absorption would have water requirements more similar to the original mixtures.

由于胶凝补充材料（SCM）可降低混凝土的全球升温潜能值，因此其使用量预计会增加。用 SCM 替代水泥时，混合物的流动性可能会发生变化。当使用大规模替代时，随着液固体积的变化，浆体的孔隙率也会发生变化。本文讨论了吸水性和单体材料比重对混合料需水量的影响。对三十多种单质进行了测试，包括十六种天然毛细管、十种煤灰、三种混合毛细管和一种磨碎的玻璃。单质材料的孔隙率是通过干燥速率测试测量的。天然灰泥的吸水率为 3.25% 至 17.25%，混合灰泥为 5.55% 至 9.25%，煤灰为 4.10% 至 18.95%，碎玻璃为 4.20%。使用 ASTM C311 测量的需水量介于 -4.25% 到 46.2% 之间。当 SCM 的比重与 OPC 的比重相差较大时，SCM 的比重尤为重要，因为这会改变液体与固体的体积比。考虑到单体材料的吸水性和单体材料的比重（通过体积置换），55% 的试样的需水量在原始混合物的 +5% 以内，以达到相同的流动性，94% 的试样的需水量在 +20% 以内。这大大低于质量置换。采用体积置换并考虑单体材料的吸收，其需水量与原始混合物更为接近。

{"title":"The effect of water absorption and specific gravity of supplementary cementitious materials on required water","authors":"Krishna Siva Teja Chopperla , Gopakumar Kaladaran , Anna K. Kochaver , O. Burkan Isgor , W. Jason Weiss","doi":"10.1016/j.cemconcomp.2024.105808","DOIUrl":"10.1016/j.cemconcomp.2024.105808","url":null,"abstract":"<div><div>The use of supplementary cementitious materials (SCM) is projected to increase because they reduce the global warming potential of concrete. When cement is replaced with SCM, the flow of the mixture may change. The porosity of the paste may also change as the liquid-to-solid volumes change when mass replacement is used. This paper discusses the role of water absorption and the specific gravity of the SCM on the water requirements of a mixture. Over thirty SCMs were tested, including sixteen natural pozzolans, ten coal ashes, three blended pozzolans, and one ground glass. The porosity of the SCM was measured using a drying rate test. The water absorbed by the natural pozzolans ranged from 3.25 to 17.25 %, 5.55–9.25 % for blended pozzolans, 4.10–18.95 % for coal ashes, and 4.20 % for ground glass. The water requirement measured using ASTM <span><span>C311</span><svg><path></path></svg></span> ranged from −4.25 to 46.2 %. The specific gravity of the SCM is particularly important when it is significantly different from the specific gravity of the OPC, as this can change the liquid-to-solid volume ratio. Accounting for the absorption of water by the SCM and the specific gravity of the SCM (via volume replacement) resulted in 55 % of the specimens having a water demand within ±5 % of the original mixture to achieve the same flow, and 94 % of the samples had a water demand within ±20 %. This was substantially less than mass replacement. Using volume replacement and accounting for SCM absorption would have water requirements more similar to the original mixtures.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105808"},"PeriodicalIF":10.8,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142450190","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

Elucidating factors on the strength of carbonated compacts: Insights from the carbonation of γ-C2S, β-C2S and C3S 阐明碳化密实物强度的影响因素：从γ-C2S、β-C2S 和 C3S 的碳化过程中获得的启示

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

Cement & concrete composites

Pub Date : 2024-10-18 DOI: 10.1016/j.cemconcomp.2024.105806

Sixue Zhao , Zhichao Liu , Fazhou Wang , Shuguang Hu

Accelerated carbonation presents a promising approach for enhancing the early strength of cement-based materials while simultaneously sequestering CO₂. This study examines the carbonation of γ-C₂S, β-C₂S, and C₃S compacts to identify the critical factors influencing strength development over extended curing periods. Analysis of the evolution of mechanical properties, microstructure, and phase assemblages reveals three key factors: 1) Degree of carbonation, which directly correlates with the density of the compacts; 2) Crystalline form and crystal size of calcium carbonate, influencing the strength of the crystal interface; and 3) Silica gels, which act as a phase boundary, with hydration products forming in the later stages of β-C₂S carbonation potentially affecting strength. The findings indicate that calcite promotes rapid strength gain in the early stages, while aragonite contributes to long-term performance. The presence of hydration products within the silica gel phase boundary may explain the observed strength reduction in β-C₂S compacts during extended carbonation. These insights provide valuable guidance for optimizing the design and application of carbonated cement-based materials for sustainable construction.

加速碳化是提高水泥基材料早期强度并同时封存二氧化碳的一种可行方法。本研究考察了 γ-C₂S、β-C₂S 和 C₃S 密实材料的碳化过程，以确定影响延长固化期强度发展的关键因素。对机械性能、微观结构和相组合演变的分析揭示了三个关键因素：1）碳化程度，它与密实物的密度直接相关；2）碳酸钙的结晶形式和晶体尺寸，它影响晶体界面的强度；3）硅凝胶，它作为相界，在 β-C₂S 碳化后期形成的水合产物可能会影响强度。研究结果表明，方解石在早期阶段能促进强度的快速提高，而文石则有助于提高长期性能。硅胶相界中水合产物的存在可能解释了在长时间碳化过程中观察到的β-C₂S压实强度降低的原因。这些见解为优化可持续建筑碳化水泥基材料的设计和应用提供了宝贵的指导。

{"title":"Elucidating factors on the strength of carbonated compacts: Insights from the carbonation of γ-C2S, β-C2S and C3S","authors":"Sixue Zhao , Zhichao Liu , Fazhou Wang , Shuguang Hu","doi":"10.1016/j.cemconcomp.2024.105806","DOIUrl":"10.1016/j.cemconcomp.2024.105806","url":null,"abstract":"<div><div>Accelerated carbonation presents a promising approach for enhancing the early strength of cement-based materials while simultaneously sequestering CO₂. This study examines the carbonation of γ-C₂S, β-C₂S, and C₃S compacts to identify the critical factors influencing strength development over extended curing periods. Analysis of the evolution of mechanical properties, microstructure, and phase assemblages reveals three key factors: 1) Degree of carbonation, which directly correlates with the density of the compacts; 2) Crystalline form and crystal size of calcium carbonate, influencing the strength of the crystal interface; and 3) Silica gels, which act as a phase boundary, with hydration products forming in the later stages of β-C₂S carbonation potentially affecting strength. The findings indicate that calcite promotes rapid strength gain in the early stages, while aragonite contributes to long-term performance. The presence of hydration products within the silica gel phase boundary may explain the observed strength reduction in β-C₂S compacts during extended carbonation. These insights provide valuable guidance for optimizing the design and application of carbonated cement-based materials for sustainable construction.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"155 ","pages":"Article 105806"},"PeriodicalIF":10.8,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142449868","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

Interlayer bonding performance of 3D printed engineered cementitious composites (ECC): Rheological regulation and fiber hybridization 三维打印工程水泥基复合材料 (ECC) 的层间粘结性能：流变调节与纤维杂化

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

Cement & concrete composites

Pub Date : 2024-10-18 DOI: 10.1016/j.cemconcomp.2024.105805

Yao Ding , Xingjian Ou , Hongtuo Qi , Gang Xiong , Tomoya Nishiwaki , Yifan Liu , Jiepeng Liu

The weak interlayer adhesion caused by the layer-by-layer 3D printing (3DP) process and the incorporation of organic fiber in Engineered Cementitious Composites (ECC), detrimentally impacts the integrity of 3DP-ECC structures, particularly for large-scale structures requiring extended open time. To optimize the printing quality and extent the operation time, cellulose filaments (CF) were employed as nano-reinforcement, viscosity modifier and water retainer, and were hybridized with polyethylene fiber (PE) and steel fiber (ST). The highest bonding strength was raised up to 3.51 MPa. The time-dependent escalation of rheological parameters was mitigated, reducing interlayer porosity to 0.56 % and limiting the reduction in bonding strength to 12.01 % within 60 min open time. The compressive anisotropy was almost eliminated, verifying the potential of CF in modifying interlayer adhesion. A linear correlation between rheological behavior and interlayer bonding performance was established, and a 0.508 Pa s/min plastic viscosity growth rate was suggested to avoid cold joint and ensure printing quality.

逐层三维打印（3DP）工艺和工程水泥基复合材料（ECC）中有机纤维的加入会导致层间附着力减弱，从而对 3DP-ECC 结构的完整性产生不利影响，尤其是对于需要延长开放时间的大型结构而言。为了优化打印质量和延长操作时间，采用纤维素丝（CF）作为纳米增强剂、粘度调节剂和保水剂，并与聚乙烯纤维（PE）和钢纤维（ST）混合。最高粘结强度提高到 3.51 兆帕。流变参数随时间变化的影响得到了缓解，层间孔隙率降低到了 0.56%，粘结强度在 60 分钟开放时间内降低了 12.01%。压缩各向异性几乎被消除，验证了 CF 在改变层间粘合力方面的潜力。流变行为与层间粘合性能之间建立了线性关系，并建议采用 0.508 Pa-s/min 的塑性粘度增长率来避免冷接合并确保印刷质量。

{"title":"Interlayer bonding performance of 3D printed engineered cementitious composites (ECC): Rheological regulation and fiber hybridization","authors":"Yao Ding , Xingjian Ou , Hongtuo Qi , Gang Xiong , Tomoya Nishiwaki , Yifan Liu , Jiepeng Liu","doi":"10.1016/j.cemconcomp.2024.105805","DOIUrl":"10.1016/j.cemconcomp.2024.105805","url":null,"abstract":"<div><div>The weak interlayer adhesion caused by the layer-by-layer 3D printing (3DP) process and the incorporation of organic fiber in Engineered Cementitious Composites (ECC), detrimentally impacts the integrity of 3DP-ECC structures, particularly for large-scale structures requiring extended open time. To optimize the printing quality and extent the operation time, cellulose filaments (CF) were employed as nano-reinforcement, viscosity modifier and water retainer, and were hybridized with polyethylene fiber (PE) and steel fiber (ST). The highest bonding strength was raised up to 3.51 MPa. The time-dependent escalation of rheological parameters was mitigated, reducing interlayer porosity to 0.56 % and limiting the reduction in bonding strength to 12.01 % within 60 min open time. The compressive anisotropy was almost eliminated, verifying the potential of CF in modifying interlayer adhesion. A linear correlation between rheological behavior and interlayer bonding performance was established, and a 0.508 Pa s/min plastic viscosity growth rate was suggested to avoid cold joint and ensure printing quality.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105805"},"PeriodicalIF":10.8,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142449869","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

Hydration process and fluoride solidification mechanism of multi-source solid waste-based phosphogypsum cemented paste backfill under CaO modification CaO 改性条件下多源固废基磷石膏胶结浆料回填的水化过程和氟化物固化机理

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

Cement & concrete composites

Pub Date : 2024-10-18 DOI: 10.1016/j.cemconcomp.2024.105804

Daolin Wang , Qing Na , Yikai Liu , Yan Feng , Qinli Zhang , Qiusong Chen

The large-scale, environmentally friendly utilization of phosphogypsum (PG) remains a global challenge. PG cemented paste backfill (PCPB) is a promising method to manage PG, but using ordinary Portland cement as the binder has drawbacks such as high cost, low mechanical strength, and high fluoride leaching risk. This paper presents a multi-source solid waste-based PCPB (MPCPB) material that enhances mechanical properties and reduces fluoride leaching risks. In MPCPB, industrial waste residues like steel slag (SS) and ground granulated blast furnace slag (GBFS) are used as precursors (SS: GBFS = 1:2). Additionally, 4–8 wt% CaO (relative to the dry weight of PG) is used as a neutralizing modifier and alkaline activator. The results indicate that an optimal amount of CaO can neutralize the residual acidity of PG, provide sufficient Ca(OH)₂ for MPCPB hydration, and react with PG to produce significant amounts of AFt. Furthermore, CaO promotes the geopolymerization reaction between SS and GBFS, generating more calcium silicate hydrate (C-S-H) and calcium aluminate silicate hydrate (C-A-S-H) gels. Fluoride stabilization in MPCPB results from synergistic effects involving hydration reactions, complexation, ionic mobility, rearrangement, and physical adsorption. Notably, CaO enhances the conversion of free fluoride ions into stable compounds like fluorapatite, fluorite (CaF₂), [AlF₆]^3-, and [FeF₆]^3- complexes. This approach offers a cost-effective, environmentally friendly, and efficient solution to the PG stockpiling challenge.

大规模、环保地利用磷石膏（PG）仍然是一项全球性挑战。磷石膏水泥浆回填（PCPB）是一种很有前景的磷石膏管理方法，但使用普通硅酸盐水泥作为粘结剂存在成本高、机械强度低、氟化物浸出风险高等缺点。本文介绍了一种基于多源固体废物的 PCPB（MPCPB）材料，它能提高机械性能并降低氟化物沥滤风险。在 MPCPB 中，钢渣（SS）和磨细高炉矿渣（GBFS）等工业废渣被用作前体（SS: GBFS=1:2）。此外，4-8 wt%的氧化钙（相对于 PG 干重）被用作中和改性剂和碱性活化剂。结果表明，最佳量的 CaO 可以中和 PG 的残余酸性，为 MPCPB 水合提供足够的 Ca(OH)2，并与 PG 反应生成大量的 AFt。此外，CaO 还能促进 SS 和 GBFS 之间的土工聚合反应，生成更多的水合硅酸钙（C-S-H）和水合硅酸铝钙（C-A-S-H）凝胶。水合反应、络合、离子迁移率、重排和物理吸附等协同效应使 MPCPB 中的氟化物趋于稳定。值得注意的是，CaO 能增强游离氟离子向氟磷灰石、萤石 (CaF2)、[AlF6]3- 和 [FeF6]3- 复合物等稳定化合物的转化。这种方法为解决 PG 储存难题提供了一种具有成本效益、环保且高效的解决方案。

{"title":"Hydration process and fluoride solidification mechanism of multi-source solid waste-based phosphogypsum cemented paste backfill under CaO modification","authors":"Daolin Wang , Qing Na , Yikai Liu , Yan Feng , Qinli Zhang , Qiusong Chen","doi":"10.1016/j.cemconcomp.2024.105804","DOIUrl":"10.1016/j.cemconcomp.2024.105804","url":null,"abstract":"<div><div>The large-scale, environmentally friendly utilization of phosphogypsum (PG) remains a global challenge. PG cemented paste backfill (PCPB) is a promising method to manage PG, but using ordinary Portland cement as the binder has drawbacks such as high cost, low mechanical strength, and high fluoride leaching risk. This paper presents a multi-source solid waste-based PCPB (MPCPB) material that enhances mechanical properties and reduces fluoride leaching risks. In MPCPB, industrial waste residues like steel slag (SS) and ground granulated blast furnace slag (GBFS) are used as precursors (SS: GBFS = 1:2). Additionally, 4–8 wt% CaO (relative to the dry weight of PG) is used as a neutralizing modifier and alkaline activator. The results indicate that an optimal amount of CaO can neutralize the residual acidity of PG, provide sufficient Ca(OH)<sub>2</sub> for MPCPB hydration, and react with PG to produce significant amounts of AFt. Furthermore, CaO promotes the geopolymerization reaction between SS and GBFS, generating more calcium silicate hydrate (C-S-H) and calcium aluminate silicate hydrate (C-A-S-H) gels. Fluoride stabilization in MPCPB results from synergistic effects involving hydration reactions, complexation, ionic mobility, rearrangement, and physical adsorption. Notably, CaO enhances the conversion of free fluoride ions into stable compounds like fluorapatite, fluorite (CaF<sub>2</sub>), [AlF<sub>6</sub>]<sup>3-</sup>, and [FeF<sub>6</sub>]<sup>3-</sup> complexes. This approach offers a cost-effective, environmentally friendly, and efficient solution to the PG stockpiling challenge.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105804"},"PeriodicalIF":10.8,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142449865","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