Cement & concrete composites最新文献_第2页

Performance evaluation of mixing carbonated reactive magnesia slurry in Portland cement pastes

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2025-03-26 DOI: 10.1016/j.cemconcomp.2025.106065

Shuang Luo , Minlu Wang , Ba Tung Pham , Nele De Belie , Tung-Chai Ling

{"title":"Performance evaluation of mixing carbonated reactive magnesia slurry in Portland cement pastes","authors":"Shuang Luo , Minlu Wang , Ba Tung Pham , Nele De Belie , Tung-Chai Ling","doi":"10.1016/j.cemconcomp.2025.106065","DOIUrl":"10.1016/j.cemconcomp.2025.106065","url":null,"abstract":"<div><div>This study uses carbonated reactive magnesia (RM) as a partial cement replacement to improve the mechanical properties of blended cement pastes. To achieve more complete and homogeneous carbonation, 30 wt% RM was first mixed at a fixed 1.67 water-RM ratio for 0–90 min (aqueous carbonation). After this, the mixture was mixed with the remaining 70 wt% ordinary Portland cement (OPC) to achieve a final water-binder ratio of 0.5. During the first 10 min of aqueous carbonation, the pH of the RM slurry dropped significantly. After 40 min, needle-like nesquehonite was detected and predominated in the system at 90 min. Mixing the carbonated RM slurries with OPC (RMP cement paste) created more nano-calcite, which covered the nesquehonite surface and served as nucleation sites to accelerate the hydration of RMP cement paste. Consequently, the setting time and fluidity of RMP cement pastes decreased with carbonation time of RM slurries used. Upon one day of hydration, nesquehonite, calcite, and vaterite coexisted in the paste. At 28 days, vaterite gradually transformed into calcite and reacted with aluminum phases to form mono-carboaluminate, densifying the microstructure and boosting the 28-day strength by 194 % compared to the control paste.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"160 ","pages":"Article 106065"},"PeriodicalIF":10.8,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143713410","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

Understanding reactivity of calcined marine clay as a supplementary cementitious material through structural transformation of clay minerals

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2025-03-26 DOI: 10.1016/j.cemconcomp.2025.106066

Zhijian Chen, Kunlin Luo, Hailong Ye

{"title":"Understanding reactivity of calcined marine clay as a supplementary cementitious material through structural transformation of clay minerals","authors":"Zhijian Chen, Kunlin Luo, Hailong Ye","doi":"10.1016/j.cemconcomp.2025.106066","DOIUrl":"10.1016/j.cemconcomp.2025.106066","url":null,"abstract":"<div><div>Compared to the fairly pure kaolinitic clay, dredged marine clay is a mixture of kaolinite, other 2:1 clay minerals (e.g. illite), and impurities like quartz. Upon thermal activation, the calcined marine clay emerges as a low-grade clay-type supplementary cementitious material (SCM). However, a thorough understanding about the underlying mechanism and key factors governing its reactivity evolution is necessary before its widespread application. In this work, the reactivity, physical properties, and mineralogical evolution of marine clay upon calcination between 650 °C and 900 °C were investigated, with particular emphasis on linking reactivity to the structural transformation of aluminosilicates in the clay. The reactivity arises from dehydroxylation and amorphization of kaolinite and 2:1 clay minerals with increasing proportion of disordered Al (4- and 5-fold coordination). After complete dehydroxylation (>650 °C), the structural disordering of the aluminosilicate continues to enhance with increasing amorphous content and more polymerised Q<sup>4</sup> framework with Al substitution. However, condensed silica networks (Si-O-Si) forms at higher temperature may hamper the reactivity. Additionally, the specific surface area of marine clay decreases significantly above 650 °C, becoming relatively low at high temperature (>750 °C) as a result of structural rearrangement of the clay minerals and interparticle sintering. The highest reactivity is achieved at 750 °C. By exhibiting comparable compressive strength to reference Portland cement mortar at 28 days at 30 % replacement level, the calcined marine clay shows potential as a sustainable SCM alternative in low-carbon concrete production.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"160 ","pages":"Article 106066"},"PeriodicalIF":10.8,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143703252","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

Active SAP desorption control in concrete through acoustic emission for optimized curing

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2025-03-26 DOI: 10.1016/j.cemconcomp.2025.106067

Eleni Korda , Annelise Cousture , Eleni Tsangouri , Didier Snoeck , Geert De Schutter , Dimitrios G. Aggelis

{"title":"Active SAP desorption control in concrete through acoustic emission for optimized curing","authors":"Eleni Korda , Annelise Cousture , Eleni Tsangouri , Didier Snoeck , Geert De Schutter , Dimitrios G. Aggelis","doi":"10.1016/j.cemconcomp.2025.106067","DOIUrl":"10.1016/j.cemconcomp.2025.106067","url":null,"abstract":"<div><div>The quality and durability of concrete strongly depend on the mixing and curing processes. Relative humidity and temperature changes can induce premature drying, resulting in shrinkage cracking. Monitoring and controlling the concrete curing process is essential in preventing undesirable behaviours. Methods such as acoustic emission (AE) have proven promising for monitoring the curing of cementitious materials due to their high sensitivity and simple application. Shrinkage cracking can be mitigated using admixtures such as superabsorbent polymers (SAPs) which provide internal curing to the concrete matrix for several hours after casting. Their action taking place in the microstructure, although beneficial, is difficult to trace or control. However, recently it was shown that the release of SAP water (desorption) into the cementitious matrix is accompanied by high AE recordings, enabling monitoring of the process. This study presents a novel methodology that uses real-time AE data to actively control internal curing, optimizing curing conditions and material properties. By treating the concrete surface with water, at the moments dictated by the increased AE signals, the SAP desorption is delayed, allowing multiple activation cycles, extending internal curing, and enhancing hydration. Results indicate improved mechanical properties, with increased compressive strength and ultrasonic pulse velocity for actively controlled SAP concrete compared to conventional SAP concrete. Finally, scanning electron microscopy (SEM) measurements near the surface, show a 70 % and 81 % reduction of cracking compared to untreated SAP concrete and conventional concrete, respectively, demonstrating the importance of active curing on the shrinkage-prone near-the-surface area.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"160 ","pages":"Article 106067"},"PeriodicalIF":10.8,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143713411","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

Inhibition mechanism of carboxylate-based inhibitors on HRB400E steel in simulated concrete pore solutions: A comprehensive consideration of passivation behavior and corrosion resistance

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2025-03-24 DOI: 10.1016/j.cemconcomp.2025.106063

Xiaocheng Zhou , Qi Ma , Man Li , Yongqi Liu , Jinjie Shi

{"title":"Inhibition mechanism of carboxylate-based inhibitors on HRB400E steel in simulated concrete pore solutions: A comprehensive consideration of passivation behavior and corrosion resistance","authors":"Xiaocheng Zhou , Qi Ma , Man Li , Yongqi Liu , Jinjie Shi","doi":"10.1016/j.cemconcomp.2025.106063","DOIUrl":"10.1016/j.cemconcomp.2025.106063","url":null,"abstract":"<div><div>Given the long-term durability needs, environmental concerns, and low-carbon requirements, the development of eco-friendly and highly effective corrosion inhibitors becomes imperative. This study selected three types of cost-effective and non-toxic carboxylate-based organic inhibitors, and comprehensively explored their impacts on the passivation behavior and corrosion resistance of HRB400E reinforcing steel in simulated concrete pore solutions. Furthermore, computational simulations were utilized to investigate the adsorption configurations of inhibitors on the steel surface, revealing their inhibition mechanisms. While carboxylate groups can enhance the effective adsorption of inhibitors onto the steel surface, the corrosion susceptibility of steel with different inhibitors varies. Despite citrate's negative effect on steel passivity, it exhibits remarkable inhibition capability, whether the steel is naturally passivated or not. These findings of this study could provide a comprehensive theoretical foundation for the application of these inhibitors in reinforced concrete structures.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"160 ","pages":"Article 106063"},"PeriodicalIF":10.8,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143695637","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

Development and validation of a mix design procedure for extruded earth bricks with cementitious stabilisation

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2025-03-23 DOI: 10.1016/j.cemconcomp.2025.106055

Solène Bouzinac , Arnaud Perrot , Simon Guiheneuf , Pascal Maillard , Jean-Emmanuel Aubert

{"title":"Development and validation of a mix design procedure for extruded earth bricks with cementitious stabilisation","authors":"Solène Bouzinac , Arnaud Perrot , Simon Guiheneuf , Pascal Maillard , Jean-Emmanuel Aubert","doi":"10.1016/j.cemconcomp.2025.106055","DOIUrl":"10.1016/j.cemconcomp.2025.106055","url":null,"abstract":"<div><div>Raw earth as a construction material is showing potential for significant development with the involvement of earth-stabilisation to improve the water resistance properties of unfired earth materials as well as enhancing the mechanical performances. However, the addition of a cementitious component as a stabilising agent can lead to rapid rheological changes including stiffening and loss of plasticity. This challenge hinders the industrial scale implementation of extrusion manufacturing process for stabilised earth bricks. To maintain the extrudability of these new clayey materials for longer period, the addition of admixtures is studied. However, there is a wide variety of products available. In this study, an experimental procedure is proposed to evaluate the performance of admixtures according to two criteria: the final water content of the formulation and the rheological evolution of the mixture observed after resting for 1 h. The results are presented in the form of a performances map. Finally, the formulations that best meet the established criteria were tested experimentally through extrusions, and a discussion was opened on the relevance of admixture on stabilised clay materials.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"160 ","pages":"Article 106055"},"PeriodicalIF":10.8,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143675501","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

Enhancing interfacial bond performance of steel fibers embedded in ultra-high-performance concrete through surface dezincification and chelation treatments

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2025-03-22 DOI: 10.1016/j.cemconcomp.2025.106062

Lu Ke , Xiulong Wu , Zheng Feng , Chuanxi Li , Doo-Yeol Yoo , Banfu Yan

{"title":"Enhancing interfacial bond performance of steel fibers embedded in ultra-high-performance concrete through surface dezincification and chelation treatments","authors":"Lu Ke , Xiulong Wu , Zheng Feng , Chuanxi Li , Doo-Yeol Yoo , Banfu Yan","doi":"10.1016/j.cemconcomp.2025.106062","DOIUrl":"10.1016/j.cemconcomp.2025.106062","url":null,"abstract":"<div><div>The flexural and tensile strength of ultra-high-performance concrete (UHPC) depend on the interfacial bond performance between the steel fibers and UHPC matrix. This study proposed a novel dezincification-chelation modification method for steel fibers, leveraging the dezincification effect of brass coating and the adsorption of chelating agents. To investigate the modification mechanisms, efficiency for fibers of varying diameters, and compare improvements, tests were conducted on dezincification, chelation, and dezincification-chelation methods. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) revealed that dezincification exposed the cold-drawn grooves of steel fibers, while chelation refined and expanded these grooves. Atomic force microscopy (AFM) showed that all treatments increased surface roughness, with dezincified-chelated fibers achieving a maximum 21.5-fold increase. All the surface treating methods improved the pullout behavior of the steel fibers, the optimal chelation and dezincification-chelation modification times of 6 h and 9 h, respectively, were independent of fiber size. The average bond strengths of the dezincified and dezincified-chelated short steel fibers increased by 45.3 % and 52.9 %, respectively, and the pullout energy increased by 96.6 % and 53.8 %, respectively, compared to the blank steel fiber. The average bond strengths of the dezincified and dezincified-chelated long steel fibers increased by 46.1 % and 64.3 %, respectively, and the pullout energy increased by 78.5 % and 70.8 %, respectively. Previous studies confirmed our findings that if the improvement in the root mean square roughness of chelated-modified steel fibers should exceed 10.0 times that of untreated steel fibers the pullout performance will decline.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"160 ","pages":"Article 106062"},"PeriodicalIF":10.8,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143675503","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

Thermodynamical analysis of the impact of chloride-rich environment on the paste mineralogy of magnesium phosphate cement

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2025-03-22 DOI: 10.1016/j.cemconcomp.2025.106061

Weiwei Han , Huisu Chen , Shaomin Song

{"title":"Thermodynamical analysis of the impact of chloride-rich environment on the paste mineralogy of magnesium phosphate cement","authors":"Weiwei Han , Huisu Chen , Shaomin Song","doi":"10.1016/j.cemconcomp.2025.106061","DOIUrl":"10.1016/j.cemconcomp.2025.106061","url":null,"abstract":"<div><div>Magnesium phosphate cement (MPC) is commonly used as rapid repair materials for damaged pavements. MPC together with pavements usually undergoes de-icing salts exposure in winter. However, the deterioration mechanism of MPC under chloride attack remains unclear. A thermodynamic simulation approach was employed to investigate the deterioration mechanism of MPC. The results revealed that compressive strength loss decreases with the increase of the concentration of the NaCl solution. Basic magnesium chlorides cannot be formed in MPC immersed in NaCl solutions. The formed MgNH<sub>4</sub>PO<sub>4</sub>·6H<sub>2</sub>O, MgKPO<sub>4</sub>·6H<sub>2</sub>O and part of the residual magnesia can dissolve in NaCl solution, facilitating the precipitation of NH<sub>4</sub>NaMg<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>·14H<sub>2</sub>O, KNaMg<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>·14H<sub>2</sub>O and brucite in MPC. Due to the precipitation of NH<sub>4</sub>NaMg<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>·14H<sub>2</sub>O and KNaMg<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>·14H<sub>2</sub>O, the volume of solid phases increases slightly and then decreases under chloride attack. NH<sub>4</sub>NaMg<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>·14H<sub>2</sub>O and KNaMg<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>·14H<sub>2</sub>O are more soluble in concentrated NaCl solution, leading to the solid volume decrease of the hardened binder phases of MPC.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"160 ","pages":"Article 106061"},"PeriodicalIF":10.8,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143675500","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

Enhancing the reaction of municipal solid waste incineration (MSWI) bottom ash in blast furnace slag-based alkali-activated blends: A novel strategy and underlying mechanism

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2025-03-20 DOI: 10.1016/j.cemconcomp.2025.106056

Boyu Chen , Guang Ye

{"title":"Enhancing the reaction of municipal solid waste incineration (MSWI) bottom ash in blast furnace slag-based alkali-activated blends: A novel strategy and underlying mechanism","authors":"Boyu Chen , Guang Ye","doi":"10.1016/j.cemconcomp.2025.106056","DOIUrl":"10.1016/j.cemconcomp.2025.106056","url":null,"abstract":"<div><div>Compared with blast furnace slag (BFS), the less reactive MSWI bottom ash (MBA) plays a minor role in alkali-activated blends. This research optimized the use of MBA as a precursor by enhancing its contribution to strength and microstructure development. The proposed strategy combines pre-treatment with pre-activation processes, enabling MBA to react before BFS addition. The NaOH-based pre-treatment led to the oxidation of metallic aluminum and the partial dissolution of the amorphous phase in MBA. The subsequent pre-activation resulted in the generation of C-A-S-H gel, which promoted later-stage gel formation in the paste. The reacted bottom ash particles exhibited distinct features in alkali-activated pastes. Compared with 100 % slag-based system, blending slag with MBA accelerated the slag reaction at late ages and facilitated the formation of a more polymerized C-(N-)A-S-H gel. The compressive strength results indicate that MBA is a promising alternative to Class F coal fly ash in BFS-based alkali-activated blends.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"160 ","pages":"Article 106056"},"PeriodicalIF":10.8,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660437","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

Use of sludge produced from reject brine as a supplementary cementitious material with enhanced carbonation capability

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2025-03-20 DOI: 10.1016/j.cemconcomp.2025.106051

Tangwei Mi , Yongqiang Li , En-Hua Yang , Cise Unluer

{"title":"Use of sludge produced from reject brine as a supplementary cementitious material with enhanced carbonation capability","authors":"Tangwei Mi , Yongqiang Li , En-Hua Yang , Cise Unluer","doi":"10.1016/j.cemconcomp.2025.106051","DOIUrl":"10.1016/j.cemconcomp.2025.106051","url":null,"abstract":"<div><div>Sludge obtained from reject brine via a novel two-step approach involving precipitation and filtration was used as a supplementary material in reactive magnesia cement (RMC) and Portland cement (PC) mixes. Detailed evaluation of the performance and microstructure of the resultant cement pastes revealed the underlying mechanism. Incorporating 25 % (of the binder content) sludge in RMC mixes significantly increased the compressive strength under ambient and carbonation-based curing, which was more than doubled under the latter condition. While the strength of PC mixes decreased with the use of sludge, it still exceeded 30 MPa under carbonation. Increase in hydration heat observed in sludge-containing mixes was attributed to the presence of brucite acting as nucleation sites. ∼30 % reduction in CO<sub>2</sub> emissions and ∼25 % reduction in energy consumption was achieved by simply incorporating sludge in the designed mixes. Furthermore, sludge enhanced carbonation in RMC and PC mixes by increasing the amount of CO<sub>2</sub> sequestered at 28 days by 25.9 % and 41.1 %, respectively. Overall, the feasibility of re-purposing reject brine by directly using the produced sludge was demonstrated, offering a sustainable alternative for concrete production with a significantly reduced environmental impact.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"160 ","pages":"Article 106051"},"PeriodicalIF":10.8,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143665984","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

Investigating the thixotropy of fresh struvite cement-based composite: Insights on mechanisms of the pastes’ thixotropic behavior

IF 10.8 1区工程技术

Cement & concrete composites Pub Date : 2025-03-20 DOI: 10.1016/j.cemconcomp.2025.106058

Ugochukwu Ewuzie , Abdulkareem O. Yusuf , Damilola Daramola , Monday U. Okoronkwo

{"title":"Investigating the thixotropy of fresh struvite cement-based composite: Insights on mechanisms of the pastes’ thixotropic behavior","authors":"Ugochukwu Ewuzie , Abdulkareem O. Yusuf , Damilola Daramola , Monday U. Okoronkwo","doi":"10.1016/j.cemconcomp.2025.106058","DOIUrl":"10.1016/j.cemconcomp.2025.106058","url":null,"abstract":"<div><div>Struvite (ST) recovered during wastewater treatment has been sparsely applied in cement-based composites. This study systematically evaluated the thixotropic behavior of cement-struvite (CST) pastes, a mix of 5–20 % ST by mass of cement, and proposed the interaction mechanisms leading to the pastes' thixotropy. The hysteresis loop area was used to establish the pastes' thixotropy and investigate its relationship with increased ST content, temperature, and yield stress. In the thixotropic behavior model used, the equilibrium shear stress was employed to examine the CST pastes' irreversible change; the characteristic time of deflocculation was used to study the flocs destruction process; and the incipient structure parameter and flocs structuration rate were used to evaluate the structure-rebuilding process quantitatively. The results revealed an enhanced CST pastes' initial structural parameter (early re-flocculation), above 1.8 times higher than the control. On the other hand, their long-term structuration rates (0.002–0.004 s<sup>−1</sup>) were lower than that of the control paste (0.006 s<sup>−1</sup>), depicting the retardation effect at the hydration products' growth stage and improved workability. The CST pastes' yield stress, plastic viscosity, and thixotropic loop area were 1.2–1.7, 1.8–8.1, and 1.1–3.6 times above the control, respectively. The results suggest the mechanism of CST pastes’ thixotropy arising from the filler effects and attractive interaction that results in early flocculation and subsequent growth of hydration products at the bridge between cement and struvite particles. The increased short-term thixotropy of CST pastes suggests enhanced buildability, essential for 3D concrete printing.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"160 ","pages":"Article 106058"},"PeriodicalIF":10.8,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143661033","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