Cement & concrete composites最新文献_第10页

Effect of the interactions between crystal and gel hydration products on the volume change of cementitious materials 晶体和凝胶水化产物之间的相互作用对胶凝材料体积变化的影响

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2024-09-18 DOI: 10.1016/j.cemconcomp.2024.105764

Depeng Zhang , Hui Li , Zhenyu Pi , Mingfeng Xu , Jian Zhou , Mingzhong Zhang

{"title":"Effect of the interactions between crystal and gel hydration products on the volume change of cementitious materials","authors":"Depeng Zhang , Hui Li , Zhenyu Pi , Mingfeng Xu , Jian Zhou , Mingzhong Zhang","doi":"10.1016/j.cemconcomp.2024.105764","DOIUrl":"10.1016/j.cemconcomp.2024.105764","url":null,"abstract":"<div><div>The volume change of cementitious materials is often studied based on the properties of the individual hydration product, either from the gel products causing shrinkage or the crystal products causing expansion. Previous studies of the team have theoretically revealed that the interactions between crystal and gel products produce the “micro self-stressing”, which affects the volume change of cementitious materials. This work presents theoretical and experimental studies into the impact of the interactions between crystal and gel products on the volume change of cementitious materials. Firstly, a theoretical model for the volume change of cementitious materials was proposed. Secondly, in the followed experiment, the crystallization pressure, which affects the interactions between crystal and gel products, was tailored by immersing specimens in different exchange solvents or solutions to change the solubility product. Water, isopropyl alcohol, ethanol, calcium hydroxide and calcium acetate were selected as the exchange solvents or solutions. Subsequently, cement pastes were vacuum dried. Volume changes of cement pastes were tested during the whole process. Inductively-coupled plasma mass spectrometry and ion chromatography were utilized to test the ion concentrations and calculate the crystallization pressure. Finally, the experimental results were compared with the calculated results to validate the model. Results indicated that cement pastes immersed in different solvents or solutions exhibited different volume changes. An increase in crystallization pressure by 45.3 % resulted in a 46.1 % increase in the expansion of cement paste. Moreover, the reduction in the interactions should be one of the factors contributing to the drying shrinkage of cement paste.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105764"},"PeriodicalIF":10.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142358708","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

Biomimetic anisotropic hydrogel as a smart self-healing agent of sustainable cement-based infrastructure 仿生各向异性水凝胶作为可持续水泥基基础设施的智能自愈合剂

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2024-09-17 DOI: 10.1016/j.cemconcomp.2024.105763

Ming Liu , Miaomiao Hu , Shuang Zou , Haichuan Lu , Jiayu Yu , Jintang Guo

{"title":"Biomimetic anisotropic hydrogel as a smart self-healing agent of sustainable cement-based infrastructure","authors":"Ming Liu , Miaomiao Hu , Shuang Zou , Haichuan Lu , Jiayu Yu , Jintang Guo","doi":"10.1016/j.cemconcomp.2024.105763","DOIUrl":"10.1016/j.cemconcomp.2024.105763","url":null,"abstract":"<div><div>The durability improvement of cement-based infrastructure is an effective strategy to achieve sustainable development and reduce the carbon footprint. In this work, a biomimetic anisotropic hydrogel, alginate/polyacrylamide/halloysite nanotubes hybrid hydrogel (SA/AM/HNTs-RDC), was fabricated as a self-healing agent to enhance the self-healing ability and extend the service life of cement-based infrastructure. The effects of SA/AM/HNTs-RDC hydrogel on the formation and deposition of healing products and the self-healing behavior of cement in the different conditions (water condition and CO<sub>2</sub>-rich condition) were investigated. Compared with the matrix hydrogel (alginate/polyacrylamide, SA/AM), the crosslinking ions and anisotropic microstructure of SA/AM/HNTs-RDC hydrogel can stimulate the massive formation and dense deposition of healing products (ettringite (AFt) and monosulfo aluminate (AFm) in the simulated water condition, calcite and AFt in CO<sub>2</sub>-rich condition) to accelerate the performance recovery of the damaged construction. The self-healing measurements exhibited that the cracks around 200 μm in the cement paste with 1 % anisotropic hydrogel (RDC1) can be sealed completely after 14-day-curing in water, and its recovery ratio of the compressive strength increased by about 10 % compared with control samples. In CO<sub>2</sub>-rich condition, the closure rate of cracks was accelerated and the complete healing of cracks with similar width only needed 7 days. The compressive strength recovery increased by 13.7 % over control samples.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105763"},"PeriodicalIF":10.8,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142306475","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

Nano-engineered the interfacial transition zone between recycled fine aggregates and paste with graphene oxide for sustainable cement composites 用氧化石墨烯对再生细骨料和浆料之间的界面过渡区进行纳米工程处理，以实现水泥复合材料的可持续发展

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2024-09-16 DOI: 10.1016/j.cemconcomp.2024.105762

Dong Lu , Fulin Qu , Yilin Su , Kai Cui

{"title":"Nano-engineered the interfacial transition zone between recycled fine aggregates and paste with graphene oxide for sustainable cement composites","authors":"Dong Lu , Fulin Qu , Yilin Su , Kai Cui","doi":"10.1016/j.cemconcomp.2024.105762","DOIUrl":"10.1016/j.cemconcomp.2024.105762","url":null,"abstract":"<div><p>The high water absorption and porosity of recycled aggregate often led to a compromised interface transition zone (ITZ), thereby adversely impacting the mechanical properties and durability of recycled aggregate concrete. This research presents a feasible, straightforward, and targeted strategy to reinforce the ITZ between recycled fine aggregate (RFA) and paste by utilizing RFA particles adsorbed with graphene oxide (GO), termed WGO@RFA. The experimental outcomes demonstrate that incorporating WGO@RFA can enhance the 28-day compressive and flexural strengths of recycled mortars by approximately 25 % and 20 %, respectively, compared to mortars containing only RFA. Furthermore, it can decrease the water sorptivity and chloride ion diffusion coefficients of recycled mortars (28 days) by about 20 % and 27 %, respectively. Notably, using WGO@RFA particles offers significant advantages, such as enhanced mechanical strengths, reduced transport properties, and a densified microstructure within the ITZ, compared to the conventional method of modifying the cement matrix with GO and then binding it with RFA. Highlighting the application of WGO@RFA shows a targeted strengthening of the ITZ, as the sub-nanometer thickness of GO adsorbed on the uneven RFA surface facilitates localized cement hydration at the ITZ. The findings of this research offer novel avenues for reusing aggregate and developing sustainable concrete.</p></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105762"},"PeriodicalIF":10.8,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142239791","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

Mechanical and shrinkage properties of cellulose nanocrystal modified alkali-activated fly ash/slag pastes 纤维素纳米晶改性碱激活粉煤灰/炉渣浆料的机械和收缩性能

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2024-09-14 DOI: 10.1016/j.cemconcomp.2024.105753

Hu Feng , Istehsan Bilal , Zhihui Sun , Aofei Guo , Zhenyun Yu , Yunxing Du , Yifan Su , Yuelong Zheng

{"title":"Mechanical and shrinkage properties of cellulose nanocrystal modified alkali-activated fly ash/slag pastes","authors":"Hu Feng , Istehsan Bilal , Zhihui Sun , Aofei Guo , Zhenyun Yu , Yunxing Du , Yifan Su , Yuelong Zheng","doi":"10.1016/j.cemconcomp.2024.105753","DOIUrl":"10.1016/j.cemconcomp.2024.105753","url":null,"abstract":"<div><div>Alkali-activated materials based on fly ash (FA) and ground granulated blast furnace slag (GGBFS) offer lower carbon footprints but face challenges like low tensile strength and shrinkage susceptibility. This research explores the potential of cellulose nanocrystals (CNC) as additives to enhance the mechanical and shrinkage properties of alkali-activated fly ash/slag (AAFS) pastes to advance sustainable construction materials. A comprehensive examination is conducted on the impact of different contents of CNC (0.05 %, 0.1 %, 0.2 %, and 0.3 % by mass of FA + GGBFS) on the properties of AAFS pastes with two different alkaline activator contents (4 % and 8 % by mass of FA + GGBFS). It is found that incorporating 0.3 % CNC into AAFS pastes respectively improves the 28-day compressive and flexural strengths by 18.54 % and 60.87 % (8 % alkaline activator) and by 16.99 % and 50.12 % (4 % alkaline activator), and reduces the autogenous shrinkage and drying shrinkage by 26.42 % and 50.32 % (8 % alkaline activator) and by 11.74 % and 22.05 % (4 % alkaline activator). Also, the flexural/compressive strength ratio of AAFS pastes is increased with increasing CNC content. The microstructural analysis shows increased hydration product formation and a smoother, more compact morphology in CNC-modified samples, which together with water retention and distribution effect and nano-reinforcing effect of CNC explains the improvements in mechanical properties and volume stability. The research findings highlight the great potential of CNC as a reinforcing agent for sustainable construction materials, aligning with the demand from industries for eco-friendly alternatives to traditional cementitious materials.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105753"},"PeriodicalIF":10.8,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319837","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

Alkaline activation via in-situ caustification of one-part binders of composite precursors of waste glass and limestone 通过原位苛化对废玻璃和石灰石复合前驱体的单组分粘合剂进行碱性活化

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2024-09-14 DOI: 10.1016/j.cemconcomp.2024.105754

Luis Edgar Menchaca-Ballinas , Piyush Chaunsali , J. Ivan Escalante-García

{"title":"Alkaline activation via in-situ caustification of one-part binders of composite precursors of waste glass and limestone","authors":"Luis Edgar Menchaca-Ballinas , Piyush Chaunsali , J. Ivan Escalante-García","doi":"10.1016/j.cemconcomp.2024.105754","DOIUrl":"10.1016/j.cemconcomp.2024.105754","url":null,"abstract":"<div><p>Mixtures of powders of waste glass (WG), limestone (LS), Na<sub>2</sub>CO<sub>3</sub> and CaO were used to formulate novel one-part in situ alkali-activated cement (WG-AAC). The in-situ interaction Na<sub>2</sub>CO<sub>3</sub>-CaO-H<sub>2</sub>O promoted the formation of CaCO<sub>3</sub> and NaOH, which promoted the WG and LS dissolution and influenced the micro- and molecular features of the resulting cementitious products. Pastes and mortars developed 1-year strengths of up to 29 MPa and were stable underwater. Characterization by XRD, SEM, EDS, and <sup>29</sup><em>Si</em>-NMR indicated that a Na<sub>2</sub>CO<sub>3</sub>:CaO ratio close to 1:1 resulted in polymerized C-S-H, CaCO<sub>3</sub>, silica gel, and Ca-modified silica gel, which were intimately intermixed and possibly crosslinked through Q<sup>3</sup> bonds. Such phases interacted synergistically improving the underwater stability of the WG-AAC, indicating that in-situ caustification is a suitable and practical alkaline activation for SiO<sub>2</sub>-rich precursors.</p></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105754"},"PeriodicalIF":10.8,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0958946524003275/pdfft?md5=b9bbd13b09e31e16d0b73fa1f99315fd&pid=1-s2.0-S0958946524003275-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142239787","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

Electrical and piezoresistive properties of ultra-high toughness cementitious composite incorporating multi-walled carbon nanotubes: Testing, analyzing, and phenomenological modeling 含有多壁碳纳米管的超高韧性水泥基复合材料的电性能和压阻性能：测试、分析和现象建模

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2024-09-11 DOI: 10.1016/j.cemconcomp.2024.105757

Chaokun Hong, Qinghua Li, Zhibin Zhuang, Hongwei Xie, Shilang Xu

{"title":"Electrical and piezoresistive properties of ultra-high toughness cementitious composite incorporating multi-walled carbon nanotubes: Testing, analyzing, and phenomenological modeling","authors":"Chaokun Hong, Qinghua Li, Zhibin Zhuang, Hongwei Xie, Shilang Xu","doi":"10.1016/j.cemconcomp.2024.105757","DOIUrl":"10.1016/j.cemconcomp.2024.105757","url":null,"abstract":"<div><p>This study explores the electrical and piezoresistive properties of ultra-high toughness cementitious composites (UHTCC) enhanced with multi-walled carbon nanotubes (MWCNTs) ranging from 0 to 1 wt% of cementitious binders. The observed polarization behavior is found to be analogous to the charging process of a capacitor. The polarization process and resistivity drift over time in the piezoresistive response are explained using an existing equivalent electrical circuit model incorporating a capacitor. The average results of electrical conductivity initially decrease and subsequently increase with higher MWCNTs concentrations, a phenomenon attributed to increased porosity and reduced matrix conductivity. The percolation threshold is identified at a volume fraction of 0.00387. Notably, even in the absence of MWCNTs, UHTCC materials exhibit piezoresistive properties due to the presence of metal impurities and ionic compounds. The insufficient polarization process results in an increasing trend in fractional change in resistance (FCR). The highest FCR sensitivity to external load occurs within the percolation threshold. Additionally, three equations are proposed to calculate electrical conductivity, incorporating the effects of interfaces, porosity, and matrix conductivity reduction, which align well with the experimental findings. These insights contribute to a deeper understanding of the electrical properties of UHTCC-MWCNTs composites, enabling more precise conductivity measurements and improved sensor sensitivity.</p></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105757"},"PeriodicalIF":10.8,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142239790","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 of carbonation, water purification and CO2 self-sequestration in hydrophobic piezo-photocatalytic carbonation coating for concrete 增强混凝土疏水性压电光催化碳化涂层的碳化、水净化和二氧化碳自封存功能

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2024-09-11 DOI: 10.1016/j.cemconcomp.2024.105756

Guanyu Liu , Hailiang Fei , Jiayu Wu , Jiaxu Zhang , Tianzheng Zhao , Wenya Guo , Xingyue Wang , Sanqiang Yang

{"title":"Enhancement of carbonation, water purification and CO2 self-sequestration in hydrophobic piezo-photocatalytic carbonation coating for concrete","authors":"Guanyu Liu , Hailiang Fei , Jiayu Wu , Jiaxu Zhang , Tianzheng Zhao , Wenya Guo , Xingyue Wang , Sanqiang Yang","doi":"10.1016/j.cemconcomp.2024.105756","DOIUrl":"10.1016/j.cemconcomp.2024.105756","url":null,"abstract":"<div><p>A eco-friendly carbonation coating (HBCC) with a piezo-photocatalysis was developed using gamma-dicalcium silicate and hydrophobic BiOI/BaTiO<sub>3</sub> (HB), aiming at purifying pollutants by multi-dimensional energy (mechanical energy and visible light) and self-sequestrating CO<sub>2</sub> produced by degrading pollutants. Based on the self-floating effect induced by the hydrophobicity of HB, the increase of catalyst content on the surface of HBCC was studied to promote the formation of a hydrophilic-hydrophobic interface. The selective adsorption of CO<sub>2</sub> and H<sub>2</sub>O molecules by the hydrophilic-hydrophobic interface of HBCC was confirmed by simulations and experiments, which accelerates carbonation. Also, carbonation degree (37.1 %), bonding strength (40.1 %), and anti-corrosion performance (15.4 %) enhanced induced by accelerating carbonation was further confirmed. Additionally, HBBC exhibits the prominent degradation effect of Rhodamine b (90.8 %), methylene blue (86.6 %), and sulfamethoxazole (74.7 %) under ultrasound and visible light within 60 min. Meanwhile, CO<sub>2</sub> emitted by piezo-photocatalytic degradation pollutants can be efficient sequestration by HBCC itself, and the carbonation can be enhanced to further improve its bonding strength. Finally, the enhancement mechanism of carbonation, water purification, and CO<sub>2</sub> self-sequestration of HBBC was explored and ascertained.</p></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105756"},"PeriodicalIF":10.8,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142274171","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

Changes in the structure of alkali activated slag mortars subjected to accelerated leaching 碱活性矿渣砂浆在加速浸出过程中的结构变化

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2024-09-10 DOI: 10.1016/j.cemconcomp.2024.105755

Thi Nhan Nguyen , Quoc Tri Phung , Diederik Jacques , Lander Frederickx , Ziyou Yu , Alexandre Dauzeres , Dimitrios Sakellariou , Jan Elsen , Yiannis Pontikes

{"title":"Changes in the structure of alkali activated slag mortars subjected to accelerated leaching","authors":"Thi Nhan Nguyen , Quoc Tri Phung , Diederik Jacques , Lander Frederickx , Ziyou Yu , Alexandre Dauzeres , Dimitrios Sakellariou , Jan Elsen , Yiannis Pontikes","doi":"10.1016/j.cemconcomp.2024.105755","DOIUrl":"10.1016/j.cemconcomp.2024.105755","url":null,"abstract":"<div><p>The chemically induced degradation of alkali-activated materials exposed to the surrounding environment is a critical concern for durability. In this study, the leaching of alkali activated slag mortars (AASs) subjected to a 6M NH<sub>4</sub>NO<sub>3</sub> solution was investigated by integrating techniques including ICP-OES, XRD/QXRD, TGA/DSC, ATR-FTIR, and <sup>29</sup>Si MAS-NMR. The results revealed that the main leachable elements from the AASs and their leaching rates decreased in the following order: Na, K, Ca, and Mg. In contrast, Si and Al, the key elements in the C-A-S-H gel, displayed a remarkable resistance to leaching. Upon NH<sub>4</sub>NO<sub>3</sub> attack, the primary phase (C-A-S-H) becomes more siliceous and has a greater mean chain length through decalcification and dealumination. The second phase, Mg, Al-layered double hydroxide (Mg, Al-LDH, or hydrotalcite), incorporated nitrate from the surrounding solution, sulfate from precursor dissolution, and Ca from gel decalcification to form nitrate/sulfate-bearing Ca, Al-LDH phases. Remarkably, the water-to-binder ratio exerted a nuanced influence, dictating the pace of element leaching, while exhibiting a relatively modest impact on the stability of the solid phases after 28 days of exposure. This work proposes a leaching mechanism for understanding the leaching process occurring in AASs based on an in-depth experimental exploration of mineralogical alterations.</p></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105755"},"PeriodicalIF":10.8,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142171600","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-slip behavior of lapped sand-coated deformed GFRP rebars in UHPC under double-row splice test 双排拼接试验下超高强度混凝土中搭接砂涂层变形 GFRP 钢筋的粘结滑移行为

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2024-09-08 DOI: 10.1016/j.cemconcomp.2024.105746

Xinyu Hu, Weichen Xue, Jiafei Jiang

{"title":"Bond-slip behavior of lapped sand-coated deformed GFRP rebars in UHPC under double-row splice test","authors":"Xinyu Hu, Weichen Xue, Jiafei Jiang","doi":"10.1016/j.cemconcomp.2024.105746","DOIUrl":"10.1016/j.cemconcomp.2024.105746","url":null,"abstract":"<div><p>Novel Ultra-High-Performance-Concrete (UHPC) structures reinforced with Fiber-Reinforced Polymer (FRP) rebars are promising candidates for applications in important infrastructures under exposed environments where normal concrete and steel rebars may falter. This paper aims to assess the bond-slip behavior between lapped sand-coated deformed Glass FRP (GFRP) rebars and UHPC using double-row splice tests, with parameters including bar diameter, splice length and lap clearance. Failure modes including the pullout of GFRP rebars and the splitting of UHPC were identified. For cases of pullout failure, the average bond strengths in samples with splice lengths of 5<em>d</em><sub><em>b</em></sub> were reduced by 17.6–22.1 % compared to those of 2.5<em>d</em><sub><em>b</em></sub>. Increasing the lap clearance from 0 to 1<em>d</em><sub><em>b</em></sub> and 2<em>d</em><sub><em>b</em></sub> led to 11.1 % and 30.2 % increases in average bond strengths. Furthermore, average bond-slip models for lapped sand-coated deformed GFRP rebars in UHPC were developed. The predicted curves matched the experimental ones, showing errors within 20 % for both average bond stresses and slips. When the cover is not less than 2<em>d</em><sub><em>b</em></sub>, the splice length is recommended to be at least 15<em>d</em><sub><em>b</em></sub> for sand-coated deformed GFRP rebars with diameters of 10 mm–16 mm in UHPC, approximately 1.25 times the corresponding development length proposed by the existing research.</p></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105746"},"PeriodicalIF":10.8,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142161669","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

Mechanism of organic additives-induced carbonation activators on affecting cement mortars 有机添加剂诱导碳化活化剂影响水泥砂浆的机理

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2024-09-07 DOI: 10.1016/j.cemconcomp.2024.105744

Shuangshuang Liu , Guangqi Xiong , Kaiyin Zhao , Lucen Hao , Yilin Su , Shipeng Zhang , Chi Sun Poon

{"title":"Mechanism of organic additives-induced carbonation activators on affecting cement mortars","authors":"Shuangshuang Liu , Guangqi Xiong , Kaiyin Zhao , Lucen Hao , Yilin Su , Shipeng Zhang , Chi Sun Poon","doi":"10.1016/j.cemconcomp.2024.105744","DOIUrl":"10.1016/j.cemconcomp.2024.105744","url":null,"abstract":"<div><p>In this study, we investigated the impact of introducing an in-situ activator, produced by carbonating cement particles in an aqueous solution, on the properties of cement mortars through secondary mixing. Two organic additives, ethylenediaminetetraacetic acid (EDTA) and glutamic acid (GLTA), were employed to enhance the leaching of calcium ions during carbonation, thereby improving the carbonation efficiency. A suite of characterization techniques revealed that the presence of organic additives could refine the carbonated particles and influence the morphology. The carbonated activators generated by this process were rich in silica gel and various polymorphic forms of calcium carbonate. These components, serving as fillers and nucleation for cement hydration, significantly accelerated the hydration process of cement mortar and promoted the formation of carboaluminate in the secondary mixing process. This approach effectively decreased the porosity of the cement mortar, refined the pore structure, and enhanced the mechanical strength.</p></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"154 ","pages":"Article 105744"},"PeriodicalIF":10.8,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142161668","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