Cement & concrete composites最新文献

{"title":"Effect of recycled concrete powder on the rheological properties of cement paste: New findings","authors":"Tian Li , Rita Nogueira , Jorge de Brito , Paulina Faria , Jiaping Liu","doi":"10.1016/j.cemconcomp.2024.105873","DOIUrl":"10.1016/j.cemconcomp.2024.105873","url":null,"abstract":"<div><div>Recycled concrete powder (RCP) influences cement paste's rheology, but the mechanisms remain unclear. This paper intends to fill this gap by employing a new method for measuring water absorption, the minimum water requirement method, an organic carbon analyser, and a laser particle size analyser. The cementitious material's water absorption (<span><math><mrow><mi>W</mi></mrow></math></span>), packing density (<span><math><mrow><msub><mi>φ</mi><mi>m</mi></msub></mrow></math></span>), water reducer adsorption (<span><math><mrow><msub><mi>Q</mi><mrow><mi>a</mi><mi>d</mi></mrow></msub></mrow></math></span>), and particle size distribution are determined. Results show that, as the RCP's content increases from 0 % to 25 %, the cementitious material's <span><math><mrow><mi>W</mi></mrow></math></span>, <span><math><mrow><msub><mi>φ</mi><mi>m</mi></msub></mrow></math></span>, <span><math><mrow><msub><mi>Q</mi><mrow><mi>a</mi><mi>d</mi></mrow></msub></mrow></math></span>, volume fraction, and average particle size increase by 21.7 %, 0.9 %, 26.2 %, 1.4 %, and 30.6 %, respectively. Consequently, the particle's surface covered by the water reducer (<span><math><mrow><mi>θ</mi></mrow></math></span>) and distance (<span><math><mrow><mi>H</mi></mrow></math></span>) decrease by 26.5 % and 32.6 %, respectively, resulting in an increase in the paste's yield stress (<span><math><mrow><msub><mi>τ</mi><mn>0</mn></msub></mrow></math></span>) and plastic viscosity (<span><math><mrow><msub><mi>η</mi><mrow><mi>p</mi><mi>l</mi></mrow></msub></mrow></math></span>) by 1946.6 % and 45.3 %, respectively. Based on an existing yield stress model, RCP affecting <span><math><mrow><msub><mi>τ</mi><mn>0</mn></msub></mrow></math></span> can be attributed to changes in the particle system's colloidal and contact interactions. A decrease in <span><math><mrow><mi>H</mi></mrow></math></span> increases colloidal interactions. Conversely, an increase in <span><math><mrow><msub><mi>φ</mi><mi>m</mi></msub></mrow></math></span> and a decrease in fine particle content reduce contact interactions. Colloidal interactions are more significant, thus <span><math><mrow><msub><mi>τ</mi><mn>0</mn></msub></mrow></math></span> increases. Based on the functional expression for the <span><math><mrow><msub><mi>η</mi><mrow><mi>p</mi><mi>l</mi></mrow></msub></mrow></math></span> developed here, RCP affecting <span><math><mrow><msub><mi>η</mi><mrow><mi>p</mi><mi>l</mi></mrow></msub></mrow></math></span> can be attributed to changes in hydrodynamic interactions and contact interactions. A decrease in <span><math><mrow><mi>H</mi></mrow></math></span> increases hydrodynamic interactions. An increase in <span><math><mrow><msub><mi>φ</mi><mi>m</mi></msub></mrow></math></span> combined with a decrease in fine particle content decrease contact interactions. Additionally, an increase in <span><math><mrow><msub><mi>Q</mi><mrow><mi>a</mi><mi>d</mi></mrow></msub></mrow></math></span> reduces pore solution's v","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"156 ","pages":"Article 105873"},"PeriodicalIF":10.8,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142735676","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}

{"title":"Effect of shrinkage-mitigating materials, fiber type, and repair thickness on flexural behavior of beams repaired with fiber-reinforced self-consolidating concrete","authors":"Jingjie Wei,&nbsp;Kamal H. Khayat","doi":"10.1016/j.cemconcomp.2024.105868","DOIUrl":"10.1016/j.cemconcomp.2024.105868","url":null,"abstract":"<div><div>While self-consolidating concrete (SCC) has emerged as a highly effective approach for the repair of concrete structures, there have been few investigations regarding the effect of the combination of different fiber and shrinkage-mitigating material types (shrinkage-reducing admixture, SRA; superabsorbent polymer, SAP; and expansive agent, EA) on the flexural behavior of repaired structures. This study aims to explore the influence of three different shrinkage-mitigating materials (1.25%–2.5 % SRA, 4%–8% EA, and 0.2%–0.4 % SAP), four fiber types (two macro synthetic fibers, MSF_A and MSF_B; 5D hooked steel fibers, 5D; a combination of 80 % 3D hooked steel +20 % short steel fibers STST) on fresh and hardened properties, cement hydration, and drying shrinkage of fiber-reinforced self-consolidating concrete (FR-SCC). Specifically, the effect of different shrinkage-mitigating materials, fiber types, and two repair thicknesses corresponding to 1/3 and 2/3 of the total height of prismatic element on the flexural performance of composite specimens repaired using FR-SCC was studied. The bond strength between existing concrete and FR-SCC was also investigated to reveal the flexural behavior of the composite beams. The results indicate that prismatic specimens repaired with FR-SCC made with 1.25 % SRA showed excellent flexural performance compared to those repaired using FR-SCC made with 4%–8% EA and 0.2%-0.4%SAP. The adverse effect of the incorporation of 4%–8% EA and 0.2%–0.4 % SAP on flexural behavior of repair specimens can be attributed to a lower existing concrete-FR-SCC interfacial and fiber-matrix bond strengths. Using SRA, EA, or SAP in FR-SCC improved bond strength with substrate by 10%–60 % compared to FR-SCC without any shrinkage-mitigating materials. The use of 1.25 % SRA showed the highest bond strength, which increased by 10%–37 % and 33%–44 %, respectively, compared to that made with SAP and EA. As the increase in the repair thickness of specimens, the incorporation of SRA, EA, or SAP had different efficiencies to enhance the flexural toughness and residual strength of the repair specimens. Furthermore, the incorporation of 5D fiber and 1.25 % SRA in SCC showed excellent flexural performance, followed by MSF_A, STST, and MSF_B fibers. The increase in the repair thickness from 1/3 to 2/3 of the total height of the composite beam enhanced the flexural toughness and residual strength by a maximum of 133 % and 160 %, respectively, attributing to fiber type and the increase in fiber volume at the cross-section of specimens.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"156 ","pages":"Article 105868"},"PeriodicalIF":10.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142713157","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}

{"title":"Thermally stimulated stiffening and fly ash's alkaline activation by Ca(OH)2 addition facilitates 3D-printing","authors":"Xiaodi Dai ,&nbsp;Sharu Bhagavathi Kandy ,&nbsp;Narayanan Neithalath ,&nbsp;Aditya Kumar ,&nbsp;Mathieu Bauchy ,&nbsp;Edward Garboczi ,&nbsp;Torben Gaedt ,&nbsp;Samanvaya Srivastava ,&nbsp;Gaurav Sant","doi":"10.1016/j.cemconcomp.2024.105870","DOIUrl":"10.1016/j.cemconcomp.2024.105870","url":null,"abstract":"<div><div>3D-printing could offer substantial benefits to the construction industry including the fabrication of customized/bespoke components, eliminating formwork, and reducing material waste. Despite these advantages, control of the pumpability, extrudability, and buildability of 3D-printed concrete (3DPC) remains challenging. This study demonstrates how the use of fly ash (FA) enables enhanced thermal stiffening, and rapid alkali-activation in the presence of portlandite (Ca(OH)₂, CH). In general, blends of CH and FA exhibit less structural build-up at low temperatures, but upon reaching a trigger temperature of 75 °C, these blends achieve rapid stiffening, at rates of ∼800 Pa/s. The rapid stiffening arises from the flocculation of CH particles, and the onset of the pozzolanic/alkali-activation reactions between CH and FA, resulting in the formation of C-A-S-H and N-A-S-H during stiffening. Careful selection of the FA-CH blend ratio, which displays an optimum at ∼20 mass % CH, enables the composition of cement-free formulations for 3D-printing applications. The outcomes have important implications on alternate feedstock pathways to compose carbon-efficient formulations for construction.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"156 ","pages":"Article 105870"},"PeriodicalIF":10.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142718892","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}

{"title":"Rheology and early-age structure development in binary and ternary blends modified with novel graphene types","authors":"Sahil Surehali ,&nbsp;Collin Gustafson ,&nbsp;Sayee Srikarah Volaity ,&nbsp;Ranjith Divigalpitiya ,&nbsp;Aditya Kumar ,&nbsp;Narayanan Neithalath","doi":"10.1016/j.cemconcomp.2024.105869","DOIUrl":"10.1016/j.cemconcomp.2024.105869","url":null,"abstract":"<div><div>Interest in the use of graphene to enhance the properties of cementitious materials is growing, but major impediments in implementation are the cost of graphene and changes in binder rheology attributable to these nanomaterials. This study explores the influence of novel, cost-effective, environment-friendly, and mass-producible graphene on the rheology and early-age structure development of cementitious binders. Two novel graphene types—fractal graphene (FG) and reactive graphene (RG)—are used in plain cement mixtures as well as those containing 30 % (by mass) of fly ash and/or limestone powder, at low dosages of ≤0.02 % by mass of binder. The early- and later-age compressive strengths are higher (by ∼5–35 %) for the graphene-modified mixtures, and they more-than-compensate for early strength reduction induced by higher cement replacement levels. Yield stress, plastic viscosity, storage modulus, and short-term thixotropy are found to be significantly higher (up to 2 times or more for yield stress, plastic viscosity, and storage modulus, and up to 3 times for short-term thixotropy) for the FG- and RG-modified pastes, with a dominant enhancement noted for the RG-modified pastes. Time-dependent storage modulus evolution using small amplitude oscillatory shear tests, supplemented with associated models indicate faster structural buildup for the FG- and RG-modified pastes due to the contributions of FG and RG to inter-particle interactions and hydration. Storage modulus evolution beyond the onset of acceleration is found to be well-related to adjusted cumulative heat of hydration and electrical conductivity values, providing rapid and inexpensive means of reliably estimating early-age structure development in cementitious systems. It is determined that ultra-low dosages (≤0.02 % by mass of binder) of FG and RG can aid in tuning the rheological and structure-development parameters, which will be beneficial towards unique applications such as 3D concrete printing and ultra-high performance concretes.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"156 ","pages":"Article 105869"},"PeriodicalIF":10.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142713156","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}

{"title":"Durability of concrete containing carbonated recycled aggregates: A comprehensive review","authors":"Tong Zhang ,&nbsp;Jiaze Cui ,&nbsp;Meng Chen ,&nbsp;Jinlai Yang ,&nbsp;Zhiguo Yan ,&nbsp;Mingzhong Zhang","doi":"10.1016/j.cemconcomp.2024.105865","DOIUrl":"10.1016/j.cemconcomp.2024.105865","url":null,"abstract":"<div><div>The utilisation of carbonated recycled aggregates in concrete has been increasingly considered as an effective strategy for CO₂ sequestration in the built environment and enhancement of concrete sustainability. Following up a pervious review on the role of carbonated recycled concrete aggregates in the mechanical properties of concrete, this paper presents a comprehensive review on the effects of carbonation treatment on the chemical compositions and physical properties of recycled concrete aggregates, as well as the role of carbonated recycled concrete aggregates in microstructure and durability-related properties including volume deformation, transport properties, chemical resistance, freeze-thaw resistance and fire resistance of concrete. A special focus is placed on the relationship between microstructure and durability-related properties of carbonated recycled aggregate concrete considering the effects of pre-treatment method, replacement level, curing age, water-to-binder ratio and quality of the original aggregates. The insights into the deterioration mechanism and strategies for improving the durability of carbonated recycled aggregate concrete are provided. This review summarises the recent advances in the field, followed by a discussion on the remaining challenges and opportunities for future research.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"156 ","pages":"Article 105865"},"PeriodicalIF":10.8,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142696508","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}

{"title":"3D printing with geopolymer-stabilized excavated earth: Enhancement of printability and engineering performance through controlled retardation","authors":"Pitabash Sahoo,&nbsp;Souradeep Gupta","doi":"10.1016/j.cemconcomp.2024.105861","DOIUrl":"10.1016/j.cemconcomp.2024.105861","url":null,"abstract":"<div><div>Excavated soil from widescale tunneling and excavation can be used in 3D-printed constructions. This research investigates the feasibility of 3D printing using geopolymer stabilized excavated soil (GP-E) containing 42% clay rich in kaolinite minerals. At dosages 0.50–1.5 wt%, sucrose is added to control the hydration and time-dependent rheological properties, enabling adequate open printing time (OPT) for large-scale printing. Experimental findings show that 1% and 1.5% sucrose addition to GP-E offers OPT of 130 min and 170 min respectively compared to 32 min for GP-E. By enabling better dispersion, the addition of sucrose allows smooth extrusion with shape retention of 90 – 92% at a lower NaOH solution-to-binder ratio (0.68) than GP-E (0.75). Sucrose and clay (in the soil) act synergistically to reduce the time-dependent static yield stress but maintain it at an adequate level of 5–8 kPa required for stacking up the layers without collapse. Flow retention and thixotropy are maintained at 100% during the printing window, which balances extrusion and buildability. As a result, the sucrose-GP-E mix could be built up to a height of 1.05 m compared to 0.19 m for GP-E. 1 % sucrose-added GP-E possesses 28 – 40% and 70% higher wet compressive strength and inter-layer bonding respectively compared to GP-E depending on the loading direction. These are linked to the refinement of capillary porosity and a 13–15% reduction in shrinkage. In summary, the findings present a potential route for controlling the printing time of geopolymer-stabilized earthen materials while reducing the embodied carbon and enhancing the mechanical performance.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"156 ","pages":"Article 105861"},"PeriodicalIF":10.8,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142696509","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}

{"title":"Wet carbonation of MSWI fly ash for sustainable limestone calcined clay cement-type composites","authors":"Miao Lu ,&nbsp;Yan Xia ,&nbsp;Jianhua Yan,&nbsp;Lei Wang","doi":"10.1016/j.cemconcomp.2024.105866","DOIUrl":"10.1016/j.cemconcomp.2024.105866","url":null,"abstract":"<div><div>The high alkalinity, chlorine, and potentially toxic elements (PTEs) content of municipal solid waste incineration fly ash (MSWI FA) hindered its potential application in construction materials. This study proposed the recovery of MSWI FA via wet carbonation and developed a novel sustainable carbonated-MSWI FA-based binder. Experimental results showed that MSWI FA achieved 12 wt% CO₂ capture through wet carbonation. Besides, wet carbonation removed 82 % of chlorine from MSWI FA and reduced the leaching risk of PTEs in both pretreatment leachate and carbonated-MSWI FA. The designed sustainable paste exhibited an outstanding 28-day compressive strength of 45.6 MPa. The chloride and sulfate salts in the carbonated-MSWI FA played an important role in hydration kinetics of pastes. Sulfate in carbonated-MSWI FA reacted with aluminate to form ettringite, and the residual chloride was captured by CO₃-Cl-AFm. The proposed wet carbonation route provided a promising and sustainable way for CO₂ capture and facilitating the application of MSWI FA in construction materials.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"156 ","pages":"Article 105866"},"PeriodicalIF":10.8,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142685074","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}

{"title":"Performance, microstructure and carbon sequestration potential of agro biochar based cement mortars","authors":"Tadi Sunil Bhagat ,&nbsp;Rathish Kumar Pancharathi","doi":"10.1016/j.cemconcomp.2024.105867","DOIUrl":"10.1016/j.cemconcomp.2024.105867","url":null,"abstract":"<div><div>This study is aimed at assessing the synergy of the biochar utilization and early age CO₂ curing on the mechanical performance, hydration and CO₂ uptake in cementitious materials. Three different biochars Bamboo biochar (BBC), Peanut Husk Biochar (PHBC) and Rice Husk Biochar (RHBC) were utilized with dosages up to 5 % by mass of cement and their influence under water curing and early age CO₂ curing was studied. Analytical studies using FTIR, XRD, TGA, SEM-EDS were extended on optimum biochar mixes for characterizing the microstructure, hydration, carbonation and CO₂ uptake of various biochar based mixes. The optimum dosage was found to be 1 % for BBC &amp; PHBC while it is 2 % in RHBC from a strength perspective. Calcium carbonate polymorphs – amorphous CaCO₃ and aragonite are found to be dominant products besides other hydration products. The biochars porous surface ability to enable hydration products precipitation is revealed. Early age CO₂ curing resulted in 23 % improved degree of hydration and 19 % improved CO₂ uptake with 2 % rice husk biochar based mix compared to control mix without biochar. The improved early age strength with 48 h CO₂ curing at flue gas CO₂ concentration of 17 % and under ambient conditions were found to be promising aspects for implementation of this method in an industrial set up for production of carbon sinking cementitious products.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"156 ","pages":"Article 105867"},"PeriodicalIF":10.8,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142684950","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}

{"title":"Transforming AOD slag toward a highly reactive mineral admixture with appreciable CO2 sequestration: Hydration behavior, microstructure evolution, and CO2 footprint","authors":"Liwu Mo ,&nbsp;Peng Liu ,&nbsp;Yahui Gu ,&nbsp;Jiahua Kuang","doi":"10.1016/j.cemconcomp.2024.105863","DOIUrl":"10.1016/j.cemconcomp.2024.105863","url":null,"abstract":"<div><div>The use of argon oxygen decarbonization slag (AODS) is restricted due to its volume unsoundness and low hydration reactivity. In this study, the feasibility of transforming AODS toward a highly reactive mineral admixture with appreciable CO₂ sequestration was investigated, the hydration behavior, evolution of the compositions and microstructures of AODS with carbonation time were systematically studied, and CO₂ footprint of carbonated AODS was elucidated. Results indicated that γ-C₂S in AODS could quickly react with CO₂ to form CaCO₃. MgO and bredigite dissolved significantly when the pH value of the slurry dropped to 7.0, leading to a significant increase in the Mg²⁺ concentration of the slurry, and promoting the conversion of calcite to monohydrocalcite. However, due to the lower Ca/Si and Ca/Mg ratios, calcium silicate (CS) and akermanite exhibited extremely low carbonation reactivity. As the carbonation time increased, the particle size of CaCO₃ gradually increased, from approximately 150 nm at 5min to approximately 400 nm at 20min, [SiO₄] gradually transited from the Q⁰, Q¹ and Q² structures to the Q³ and Q⁴ structures, ultimately forming a large amount of amorphous SiO₂ gel, which led to an obvious increase in specific surface area of AODS. The compressive strength of cement mortar mixed with 20 wt% carbonated AODS (CAODS) was increased by 25.8 % compared with that of the mortar incorporating AODS. The CO₂ sequestration capacity of AODS can reach approximately 200 kg/t, and 193.4 kg CO₂ can be cut when 1 ton of CAODS-based composite cement with excellent cementitious properties is produced.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"156 ","pages":"Article 105863"},"PeriodicalIF":10.8,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678318","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}

{"title":"Nano-engineering steel fiber for UHPC: Implication for varying cryogenic and elevated exposure","authors":"Bei He ,&nbsp;Xinping Zhu ,&nbsp;Hongen Zhang ,&nbsp;Aiguo Wang ,&nbsp;Daosheng Sun ,&nbsp;Nemkumar Banthia ,&nbsp;Zhengwu Jiang","doi":"10.1016/j.cemconcomp.2024.105851","DOIUrl":"10.1016/j.cemconcomp.2024.105851","url":null,"abstract":"<div><div>The interfacial bonding between steel fibers and Ultra-High Performance Concrete (UHPC) matrix is pivotal for the mechanical properties in extreme environments. Herein, a surface nanoengineering approach using the sol-gel method was reported to enhance the resistance of fiber bonding to varying cryogenic and elevated exposures (−170 °C ∼ 200 °C). Additionally, the interfacial bonding and failure of the steel fiber-matrix interface were evaluated by in-situ acoustic emission (AE) monitoring and a series of microscopic characterizations. The result indicated that the deposition of a nano-SiO₂ coating with a film structure thickness of approximately 150 nm on fiber surface could be achieved. The coating exhibited excellent cryogenic resistance but inferior elevated resistance, as elevated temperatures caused the coating to crack and corrode. After modification, the interfacial bonding stability exposed to thermal variations was enhanced. At ambient temperature, the bond strength of the modified fibers increased by 44.68 % compared to before modification, while that increased by 1.54 %–13.49 % in a single thermal-variations cycle compared to the ambient modified group. Interface enhancement arises from imbalances in nanocoating thermal stability, moisture phase changes, properties of three-phase interface transition zone, and thermal expansion coefficient disparities. Those findings provide new insight into the attempts to improve the mechanical and durability properties of concrete under extreme temperature environments.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"156 ","pages":"Article 105851"},"PeriodicalIF":10.8,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142673127","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}