Cement & concrete composites最新文献

{"title":"Quantitative evaluation for fracture properties of 3D printed ultra-high-performance concrete loaded in different directions","authors":"Shutong Yang,&nbsp;Zhengyuan Chen,&nbsp;Tian Lan,&nbsp;Tiange Yang","doi":"10.1016/j.cemconcomp.2025.106110","DOIUrl":"10.1016/j.cemconcomp.2025.106110","url":null,"abstract":"<div><div>The integration of ultra-high-performance concrete (UHPC) with 3D printing technology introduces the revolutionary potential, offering exceptional mechanical properties, enhanced design flexibility, and automated construction processes. However, without additional reinforcement, the fracture performance of 3D-printed UHPC (3DP-UHPC) becomes critical to the crack resistance structures. To address the gaps in existing research, this study developed a closed-form fracture model to evaluate its fracture properties in varying loading conditions and copper-plated straight steel fiber dosages. The fracture mechanisms of 3DP-UHPC under different loading directions were systematically analyzed using fracture tests on 155 beams. By introducing the meso-structural characteristic parameter (<em>C</em>_ch) and discrete coefficients indicating the heterogeneity and discontinuity of 3DP-UHPC, the fracture model was developed allowing for determining size-independent tensile strength (<em>f</em>_t) and fracture toughness (<em>K</em>_IC). The results revealed that <em>C</em>_ch proved to be the average aggregate size for specimens loaded aligned with the printing direction and the average fiber spacing in other loading directions. The fracture properties of 3DP-UHPC exhibited pronounced directional dependency, with <em>f</em>_t and <em>K</em>_IC significantly higher when the specimens were loaded in the vertical direction of the printing compared to parallel loading. The fibers substantially improved the fracture resistance, particularly at the 1.5 % dosage, where fibers aligned perpendicular to the cracked section contributed most to crack resistance, achieving <em>f</em>_t of 49.43 MPa and <em>K</em>_IC of 5.28 MPa∙m^1/2. The reliability of the model was statistically validated by incorporating results of specimens with varying notch-to-height ratios and heights into the normality analysis, confirming the size independence of the derived fracture parameters.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"162 ","pages":"Article 106110"},"PeriodicalIF":10.8,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066164","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":"A novel ultra-high residual strength-enhanced geopolymer incorporated corundum aggregates after elevated temperature exposure","authors":"Yi Li ,&nbsp;Ruiwen Jiang ,&nbsp;Xinyi Ran ,&nbsp;Peipeng Li","doi":"10.1016/j.cemconcomp.2025.106137","DOIUrl":"10.1016/j.cemconcomp.2025.106137","url":null,"abstract":"<div><div>In order to improve the high temperature resistance of building materials and develop a material that does not need to be repaired after fire, this paper develops a novel high temperature resistant geopolymer with metakaolin-fly ash blended precursor and corundum aggregates, characterized by thermal enhanced ultra-high residual strength. The surface morphology, mass loss, volume shrinkage, compressive strength, mineral composition, nanomechanical properties, microstructure, and pore distribution of geopolymer mortar before and after exposure to elevated temperatures ranging from 20 to 1000 °C are tested and analyzed. The effects of different aggregate types, volume fractions and particle size gradations on performance evolution and thermal incompatibility in geopolymer mortar are clarified and discussed. The results show that corundum aggregates utilization can significantly improve the mechanical properties and high temperature resistance of geopolymer mortar. The finer corundum aggregates with a smaller fineness modulus of 1.55 tends to better alleviate aggregates deterioration and mitigate thermal incompatibility between aggregate and geopolymer paste, thus improves the microstructure and pore distribution, residual compressive strength of the geopolymer mortar after high temperatures. With the increase of exposure temperatures, the designed geopolymer materials innovatively experiences a continuously enhanced strength attributed to the excellent precursor sintering and aggregate thermal compatibility, instead of severe strength degradation in most normal cementitious materials. By using corundum aggregate and optimized particle size distribution, the ultra-high residual compressive strength and strength retention rate could be achieved after exposure to 1000 °C for 1 h up to 148.5 MPa and 272 %, respectively.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"162 ","pages":"Article 106137"},"PeriodicalIF":10.8,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143980134","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":"Zinc acetate as a set retarder for magnesium potassium phosphate cements","authors":"Biwan Xu ,&nbsp;Frank Winnefeld ,&nbsp;Barbara Lothenbach","doi":"10.1016/j.cemconcomp.2025.106114","DOIUrl":"10.1016/j.cemconcomp.2025.106114","url":null,"abstract":"<div><div>The development of not-toxic retarders with a high retardation efficiency is crucial for a sustainable development of high-performance magnesium potassium phosphate (MKP) cement-based materials. Zinc acetate is such a promising new set retarder for MKP cements. The impact of zinc acetate on the properties and hydration of the MKP cements at a Mg/PO₄ molar ratio of 8 was investigated up to 5 years. Zinc acetate had a much stronger retardation effect than borax at the same dosage, but also decreased flowability, increased drying shrinkage and led to a slower strength gain. The combined effect of zinc and acetate ions led to a lowered pH and the delayed formation of K-struvite at very early hydration times. K-struvite, amorphous magnesium (and/or zinc)-containing phosphates, an acetate-containing phase and some brucite were formed in the hardened matrix at late ages. The zinc ions were immobilized in the hydrated paste matrix, ensuring the safe use of zinc acetate as a retarder for MKP cements.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"162 ","pages":"Article 106114"},"PeriodicalIF":10.8,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066500","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":"Post-heating flexural behavior of CFRP bar in ultra-high-performance fiber-reinforced concrete (UHPFRC) members after thermal exposure","authors":"Sun-Jae Yoo ,&nbsp;Jean-Luc Malan Parr ,&nbsp;Mingzhong Zhang ,&nbsp;Jun-Mo Yang ,&nbsp;Young-Soo Yoon","doi":"10.1016/j.cemconcomp.2025.106136","DOIUrl":"10.1016/j.cemconcomp.2025.106136","url":null,"abstract":"<div><div>The post-heating flexural performance of carbon fiber-reinforced polymer (CFRP) bars after thermal exposure plays a critical role in determining whether concrete members should be demolished or strengthened. This study investigates post-heating flexural performance of a CFRP bar in ultra-high-performance fiber-reinforced concrete (UHPFRC) after thermal exposure. A total of six UHPFRC members were prepared, and were exposed up to 200, 400, and 600 °C with unheated members serving as a control group, and the results were also compared to that of UHPFRC reinforced with steel bars. After thermal exposure at 200 °C, the ultimate load of the CFRP bar reinforced UHPFRC increased by approximately 16.7 % compared to the unheated member, but it dropped by 41.4 and 83.5 % after thermal exposure at 400 and 600 °C. For steel bar reinforced UHPFRC members, ultimate load decreased by approximately 33.4 %, with bar rupture observed after exposure at 600 °C. Thermal cracks appeared along the longitudinal direction after exposure at 400 °C, but no thermal cracks were observed after exposure at 600 °C. For CFRP bar reinforced UHPFRC members, the initiation of slip was accelerated with increasing temperatures, whereas almost zero slip was observed for steel bars at ambient and after thermal exposure at 600 °C. For sectional analysis, the materials were modeled to account for the modified tensile strength of CFRP bars after exposure at 400 and 600 °C. The flexural strength predicted by the sectional analyses showed good agreement with the experimental results, with an average ratio of 0.98 between experimental and predicted results.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"162 ","pages":"Article 106136"},"PeriodicalIF":10.8,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143980039","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":"Design of alkali-activated phosphorus slag binders for Cr(VI) Immobilization: Thermodynamic modelling and experimental insights","authors":"Lang Pang ,&nbsp;Dengquan Wang ,&nbsp;Qiang Wang","doi":"10.1016/j.cemconcomp.2025.106124","DOIUrl":"10.1016/j.cemconcomp.2025.106124","url":null,"abstract":"<div><div>Alkali-activated materials offer a low-carbon and cost-effective approach for heavy metal immobilization. In this study, alkali-activated phosphorus slag (AA-PS) mixtures were designed to immobilize Cr(VI). This research integrates thermodynamic modelling and experiments to investigate the reaction processes, immobilization mechanisms, and leaching behaviors. The results show that the hydration products of NaOH-activated PS include C-(N)-A-S-H gel, hydrotalcite, and strätlingite. Among them, hexagonal plate-like hydrotalcite is the key mineral phase to immobilize Cr(VI), which is first directly observed in a real AA-PS hydrated binder. A 6 % NaOH content achieves satisfactory compressive strength and high Cr(VI) immobilization efficacy exceeding 99.99 % even at 3 days. Under acidic conditions, the hydration products provide buffering capacity, and hydrotalcite can efficiently immobilize Cr(VI) when the inner pH is above 10.5. Meanwhile, CaCrO₄ can contribute to Cr(VI) immobilization when the pH is above 7. Only when the internal pH drops below 7, significant Cr leaching begins. These findings provide scientific basis for the value-added utilization of phosphorus slag and the immobilization of Cr(VI).</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"162 ","pages":"Article 106124"},"PeriodicalIF":10.8,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143946218","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":"Development of CO2-activated interface enhancer to improve the interlayer properties of 3D-printed concrete","authors":"Hao Lucen ,&nbsp;Lyu Hanxiong ,&nbsp;Zhang Huanghua ,&nbsp;Zhang Shipeng ,&nbsp;Xiao Jianzhuang ,&nbsp;Poon Chi Sun","doi":"10.1016/j.cemconcomp.2025.106122","DOIUrl":"10.1016/j.cemconcomp.2025.106122","url":null,"abstract":"<div><div>This paper presents an approach to enhance the interlayer properties of 3D-printed concrete (3DPC) by synchronously spraying CO₂-activated interface enhancer (CIE) onto the surface of printed concrete filament during the printing process, thus overcoming the inherent limitation of weak interlayer properties and unlocking new possibilities for automation construction. The CIE was developed by using dicalcium silicate (C₂S), a binder mineral with high carbonation activity. It was found that applying a 100 μm thick CIE resulted in a remarkable enhancement ratio of 249.3 % in the interlayer strength of 3DPC at 28 days. Subjected carbonation, CIE produced calcium carbonates and silica gel, which effectively filled the interlayer microstructure, leading to a reduced porosity. Furthermore, the activation of the CIE led to the growth of spear-like calcium carbonate crystals and rod-like ettringite crystals, which played a crucial role in enhancing the bonding performance by forming an interlocking microstructure. Contrary to common belief, a prolonged printing interval was beneficial for CIE, as it allowed for increased CO₂ penetration, thereby enhancing the carbonation degree. In conclusion, the CIE developed in this study can be considered a promising approach for enhancing the interlayer properties of 3DPC.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"162 ","pages":"Article 106122"},"PeriodicalIF":10.8,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143940452","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":"Enabling carbon dioxide mineralization and active set control in portlandite-based cementitious suspensions","authors":"Xiaodi Dai ,&nbsp;Sharu Bhagavathi Kandy ,&nbsp;Rui Xiao ,&nbsp;Manas Sarkar ,&nbsp;Shubham Wani ,&nbsp;Thiyagarajan Ranganathan ,&nbsp;Narayanan Neithalath ,&nbsp;Aditya Kumar ,&nbsp;Mathieu Bauchy ,&nbsp;Edward Garboczi ,&nbsp;Torben Gädt ,&nbsp;Samanvaya Srivastava ,&nbsp;Gaurav Sant","doi":"10.1016/j.cemconcomp.2025.106123","DOIUrl":"10.1016/j.cemconcomp.2025.106123","url":null,"abstract":"<div><div>The real-time control of concrete's stiffening allows users to better control pumping and extrusion during 3D-printing processes. Here, a portlandite-based cementitious formulation (i.e., slurry or suspension) that features the potential for rapid CO₂ uptake is adapted for 3D-printing applications. In particular, we showcase a portlandite-fly ash binder system combined with a thermoresponsive polymer, wherein precise control via thermal activation allows set control and rapid solidification. Through the thermally induced polymerization of polyacrylamide, the hybrid binder system rapidly undergoes stiffening at trigger onset temperatures ranging from 60 °C to 80 °C, exhibiting average stiffening rates of up to 2600 Pa s⁻¹. The addition of fly ash is noted to extend the open time, reduce the yield stress, and improve pumpability. The polymerization process contributes to initial strength gain. Subsequently, portlandite's carbonation and fly ash's pozzolanic reaction enhances mechanical strength. By combining set control and CO₂ mineralization, this work pioneers the development of CO₂-cured 3D-printed construction materials.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"162 ","pages":"Article 106123"},"PeriodicalIF":10.8,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143940450","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 phase formation of cement pastes incorporating CO2-activated steel slag as a supplementary cementitious material","authors":"Ning Li,&nbsp;Cise Unluer","doi":"10.1016/j.cemconcomp.2025.106121","DOIUrl":"10.1016/j.cemconcomp.2025.106121","url":null,"abstract":"<div><div>With the growing interest in utilizing metallurgical slag for mineral carbonation, there is an urgent need to explore the application of flue gas-carbonated slag. This study investigated the microstructure of steel slag powder (SSP) carbonated under 10 % CO₂ concentration and its impact on the hydration, rheological behavior and compressive strength of cement pastes. The primary carbonation products of SSP were nano-CaCO₃ and amorphous aluminosilicate gel, with aragonite and calcite forming as the main calcium carbonate crystals. Nano-CaCO₃ and amorphous gel actively participated in cement hydration, forming monocarboaluminate and C-S-H gel, respectively. These reactions enhanced the degree of hydration and strengthened the interface between SSP and the hydrated cement matrix. In addition, the incorporation of moderately carbonated SSP (3 h) improved flow stability and reduced thixotropy due to better particle dispersion, while extended carbonation increased viscosity and structural recovery. The compressive strength of cement pastes containing 20 wt% SSP carbonated for 3 h was 21.6 % higher than those with uncarbonated SSP, along with a 4.5 % CO₂ uptake in SSP. However, a higher degree of carbonation reduced the reactivity of SSP as a supplementary cementitious material (SCM). This study provides scientific insights and a practical method for preparing a high-quality SCM by utilizing flue gas and SSP as a cement substitute.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"162 ","pages":"Article 106121"},"PeriodicalIF":10.8,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143933227","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":"Quantitative influence of conditions on CO2-activation quality in recycled cement paste powder: content, morphology and chemical reactivity of target product and CO2 sequestration capacity","authors":"Yaogang Tian,&nbsp;Jing Jiang,&nbsp;Kuo Ji,&nbsp;Jin Tian,&nbsp;Junpeng Yang,&nbsp;Kan Jia,&nbsp;Xin Lu","doi":"10.1016/j.cemconcomp.2025.106120","DOIUrl":"10.1016/j.cemconcomp.2025.106120","url":null,"abstract":"<div><div>Cement clinker production is a major contributor to CO₂-intensive emissions and high energy consumption in the cement industry, necessitating urgent development of sustainable alternatives. In this study, thus, a CO₂-activation recycled cement paste powder (ca-RCPP) with pozzolanic activity and aragonite whisker was synthesized by enhancing recycled cement paste powder (RCPP) through CO₂. Meantime, the change rule of CO₂-activation quality of ca-RCPP was quantitatively investigated and the related effect mechanism was elucidated under different CO₂-activation conditions. The results showed that ca-RCPP was dominated by calcite under high CO₂ dissolution conditions. Increasing the concentration of crystal modifier (MgCl₂·6H₂O), CO₂-activation temperature and rotation speed promoted a moderate reduction in CO₃²⁻ saturation, which enhanced both the content and length-diameter ratio (L/D) of aragonite, thereby improving the chemical reactivity of ca-RCPP with 3CaO·Al₂O₃. However, excessively low CO₃²⁻ saturation levels were proved counterproductive. Concurrently, silica gel content and CO₂ sequestration efficiency (<em>β</em>) always decreased under these conditions. Prolonged CO₂-activation time increased aragonite content, <em>β</em>, silica gel content and pozzolanic activity of ca-RCPP, but shortened the L/D of aragonite. Elevated gas flux of CO₂ similarly enhanced <em>β</em> and silica gel content, but diminished both the content and L/D of aragonite. Correlation analysis demonstrated an overall synergistic relationship between these evaluation indexes of CO₂-activation quality under the influence of most CO₂-activation conditions. Additionally, the concentration of crystal modifier, CO₂-activation time and CO₂-activation temperature exerted greater influence on the CO₂-activation quality of ca-RCPP than gas flux of CO₂ or rotation speed.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"162 ","pages":"Article 106120"},"PeriodicalIF":10.8,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143933340","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":"Chloride-induced corrosion of galvanized steel in ordinary Portland cement and alkali-activated fly ash mortars with benzotriazole","authors":"Jinjie Shi ,&nbsp;Xiangdong Guan","doi":"10.1016/j.cemconcomp.2025.106117","DOIUrl":"10.1016/j.cemconcomp.2025.106117","url":null,"abstract":"<div><div>Galvanized steel can be passivated in ordinary Portland cement (OPC) due to the formation of a protective calcium hydroxyzincate (CHZ) layer. However, it is rarely concerned about the corrosion resistance of galvanized steel in alkali-activated fly ash (AAFA). Accordingly, this study evaluated the passivation performance and chloride-induced corrosion behavior of galvanized steel in OPC and AAFA mortars, and the impact of benzotriazole (BTA) on the corrosion resistance of galvanized steel was also investigated. The results demonstrated that, unlike OPC mortar, AAFA mortar failed to provide effective protection for galvanized steel due to the inability to form a stable CHZ protective layer. This phenomenon primarily results from the rapid dissolution of the galvanized coating by the alkali activator during the early hydration stage, combined with the lack of adequate calcium ions in the highly alkaline pore solutions. Moreover, BTA enhanced the corrosion resistance of galvanized steel in OPC mortar, whereas it exhibited no inhibition effect in AAFA mortar. These findings could enhance our understanding towards the design of novel low-carbon and high-durable concrete structures.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"162 ","pages":"Article 106117"},"PeriodicalIF":10.8,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143932652","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}