This article presents the investigation findings on the combined effect of seawater and carbonation curing on two types of binders – blended binder containing blast furnace slag (BFS) and laboratory synthesized pure β-C2S. Samples were prepared using freshwater and seawater as mixing water. After casting, the samples were exposed to accelerated CO2 curing for 7 days and then exposed to seawater for up to 56 days. The results revealed that the use of seawater as mixing water has substantially different effects on the performances of β-C2S compared to blended cement. Specifically, the use of seawater as the mixing water resulted in a threefold increase in the amount of carbonates formation in β-C2S paste compared to the samples prepared by mixing with fresh water. The seawater mixed and CO2 cured β-C2S paste samples showed continuous increase in strength even after extended exposure to seawater and reached up to 75 MPa strength, which is nearly 100% increase compared to the samples prepared with freshwater mixing. However, such drastic benefits of using seawater were not observed in the case of blended binders. For pure β-C2S, the presence of Mg ions along with slightly higher pH resulted in the formation of vaterite and Mg-calcite contributing to superior performances. Additionally, after exposure to seawater, the silica gel phase captured Mg from seawater to form M-S-H. On the hand, the presence of Al in blended cement led to the formation of layered double hydroxides, including hydrotalcite and hydrocalumite, which limited the benefits of using seawater. Additionally, the presence of Al also resulted in the formation of ettringite formation when exposed to seawater. Because of these effects, a slight reduction in strength was observed in case of carbonation cured blended cement after their exposure to seawater.
{"title":"New insights into the interaction between seawater and CO2-activated calcium silicate composites","authors":"Farzana Mustari Nishat, Ishrat Baki Borno, Adhora Tahsin, Warda Ashraf","doi":"10.1016/j.cemconcomp.2025.105929","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.105929","url":null,"abstract":"This article presents the investigation findings on the combined effect of seawater and carbonation curing on two types of binders – blended binder containing blast furnace slag (BFS) and laboratory synthesized pure β-C<sub>2</sub>S. Samples were prepared using freshwater and seawater as mixing water. After casting, the samples were exposed to accelerated CO<sub>2</sub> curing for 7 days and then exposed to seawater for up to 56 days. The results revealed that the use of seawater as mixing water has substantially different effects on the performances of β-C<sub>2</sub>S compared to blended cement. Specifically, the use of seawater as the mixing water resulted in a threefold increase in the amount of carbonates formation in β-C<sub>2</sub>S paste compared to the samples prepared by mixing with fresh water. The seawater mixed and CO<sub>2</sub> cured β-C<sub>2</sub>S paste samples showed continuous increase in strength even after extended exposure to seawater and reached up to 75 MPa strength, which is nearly 100% increase compared to the samples prepared with freshwater mixing. However, such drastic benefits of using seawater were not observed in the case of blended binders. For pure β-C<sub>2</sub>S, the presence of Mg ions along with slightly higher pH resulted in the formation of vaterite and Mg-calcite contributing to superior performances. Additionally, after exposure to seawater, the silica gel phase captured Mg from seawater to form M-S-H. On the hand, the presence of Al in blended cement led to the formation of layered double hydroxides, including hydrotalcite and hydrocalumite, which limited the benefits of using seawater. Additionally, the presence of Al also resulted in the formation of ettringite formation when exposed to seawater. Because of these effects, a slight reduction in strength was observed in case of carbonation cured blended cement after their exposure to seawater.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carbonation is a natural process in concrete where atmospheric CO2 diffuses into the pores of the material and reacts with cement hydrates to form calcium carbonate. Although this process can help to sequester atmospheric CO2 and mitigate rising levels in urban areas, it slows down over time, resulting in low CO2 uptake over the service life of concrete. This study proposes a sustainable method to improve carbonation kinetics and CO2 capture in cement materials by incorporating highly porous biochar. The biochar, derived from seaweed pyrolysis, has a highly developed surface area, including micropores optimised for CO2 adsorption, mesopores and macropores, as well as oxygen-rich surface groups. These properties allow the biochar to efficiently adsorb CO2 and retain water. The biochar particles embedded in the cement matrix act as reservoirs for water and CO2, influencing hydration and carbonation. The addition of biochar increases water retention in the composite, which promotes the formation of capillary pores and enhances the carbonation process. Experimental data and numerical simulations show that the adsorption of CO₂ in the micropores of biochar facilitates the flow of CO2 through the composite, allowing deeper carbonation. The interaction between biochar and cement matrix enhances CO2 diffusion and promotes calcium carbonate formation both within the biochar and at the biochar-cement interface, further improving CO2 uptake. The study demonstrates that the incorporation of porous biochar into cement materials significantly increases their potential for CO2 capture, offering a promising approach to sustainable construction and carbon sequestration.
{"title":"Porous biochar for improving the CO2 uptake capacities and kinetics of concrete","authors":"Matthieu Mesnage, Rachelle Omnée, Johan Colin, Hamidreza Ramezani, Jena Jeong, Encarnacion Raymundo-Piñero","doi":"10.1016/j.cemconcomp.2025.105932","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.105932","url":null,"abstract":"Carbonation is a natural process in concrete where atmospheric CO<sub>2</sub> diffuses into the pores of the material and reacts with cement hydrates to form calcium carbonate. Although this process can help to sequester atmospheric CO<sub>2</sub> and mitigate rising levels in urban areas, it slows down over time, resulting in low CO<sub>2</sub> uptake over the service life of concrete. This study proposes a sustainable method to improve carbonation kinetics and CO<sub>2</sub> capture in cement materials by incorporating highly porous biochar. The biochar, derived from seaweed pyrolysis, has a highly developed surface area, including micropores optimised for CO<sub>2</sub> adsorption, mesopores and macropores, as well as oxygen-rich surface groups. These properties allow the biochar to efficiently adsorb CO<sub>2</sub> and retain water. The biochar particles embedded in the cement matrix act as reservoirs for water and CO<sub>2</sub>, influencing hydration and carbonation. The addition of biochar increases water retention in the composite, which promotes the formation of capillary pores and enhances the carbonation process. Experimental data and numerical simulations show that the adsorption of CO₂ in the micropores of biochar facilitates the flow of CO<sub>2</sub> through the composite, allowing deeper carbonation. The interaction between biochar and cement matrix enhances CO<sub>2</sub> diffusion and promotes calcium carbonate formation both within the biochar and at the biochar-cement interface, further improving CO<sub>2</sub> uptake. The study demonstrates that the incorporation of porous biochar into cement materials significantly increases their potential for CO<sub>2</sub> capture, offering a promising approach to sustainable construction and carbon sequestration.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-09DOI: 10.1016/j.cemconcomp.2025.105930
Maciej Szeląg, Patryk Rumiński, Rafał Panek
This study examines the effects of highly reactive, mesoporous MCM-41 silica on the thermal resistance and microstructural stability of Portland cement paste (CP). The motivation is to enhance cement composites (CC) properties using supplementary cementitious materials (SCMs), addressing environmental challenges from global cement production. The research involved modifying CP with 0-2 wt.% MCM-41 and subjecting it to thermal loads from 20°C to 700°C. Evaluations included compressive and tensile strengths, density, water absorption, and shrinkage. Characterization techniques like X-ray diffraction (XRD) and mercury intrusion porosimetry (MIP) analysed phase composition and pore distribution. Results showed that MCM-41 significantly improved compressive strength, with a 26.9% increase at 0.75 wt.% content. Tensile strength also improved up to 33.8% for 0.25-1 wt.% MCM-41 content. Thermal stability tests indicated enhanced performance in the 200-500°C range by reducing microcrack formation. XRD analysis revealed that MCM-41 influenced the phase composition, particularly delaying the thermal decomposition of portlandite and enhancing the stability of calcium silicate hydrates (CSH). Microstructural analysis revealed a denser, more cohesive cement matrix with reduced water absorption and shrinkage, enhancing durability. Additionally, MIP studies showed that MCM-41 contributed to a finer pore structure, improving the overall mechanical properties despite increased porosity. To supplement the findings, peak models have been tested to assess the ability to numerically predict pore size distribution of thermally loaded CP. Thus, MCM-41 is effective for improving the thermal and mechanical properties of CP, offering potential for applications in thermally stressed environments, contributing to more sustainable construction materials.
{"title":"Microstructure transformation of MCM-41 modified cement paste subjected to thermal load and modelling of its pore size distribution","authors":"Maciej Szeląg, Patryk Rumiński, Rafał Panek","doi":"10.1016/j.cemconcomp.2025.105930","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.105930","url":null,"abstract":"This study examines the effects of highly reactive, mesoporous MCM-41 silica on the thermal resistance and microstructural stability of Portland cement paste (CP). The motivation is to enhance cement composites (CC) properties using supplementary cementitious materials (SCMs), addressing environmental challenges from global cement production. The research involved modifying CP with 0-2 wt.% MCM-41 and subjecting it to thermal loads from 20°C to 700°C. Evaluations included compressive and tensile strengths, density, water absorption, and shrinkage. Characterization techniques like X-ray diffraction (XRD) and mercury intrusion porosimetry (MIP) analysed phase composition and pore distribution. Results showed that MCM-41 significantly improved compressive strength, with a 26.9% increase at 0.75 wt.% content. Tensile strength also improved up to 33.8% for 0.25-1 wt.% MCM-41 content. Thermal stability tests indicated enhanced performance in the 200-500°C range by reducing microcrack formation. XRD analysis revealed that MCM-41 influenced the phase composition, particularly delaying the thermal decomposition of portlandite and enhancing the stability of calcium silicate hydrates (CSH). Microstructural analysis revealed a denser, more cohesive cement matrix with reduced water absorption and shrinkage, enhancing durability. Additionally, MIP studies showed that MCM-41 contributed to a finer pore structure, improving the overall mechanical properties despite increased porosity. To supplement the findings, peak models have been tested to assess the ability to numerically predict pore size distribution of thermally loaded CP. Thus, MCM-41 is effective for improving the thermal and mechanical properties of CP, offering potential for applications in thermally stressed environments, contributing to more sustainable construction materials.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-09DOI: 10.1016/j.cemconcomp.2025.105924
Jionghuang He, Yingliang Zhao, Yong Tao, Peiliang Shen, Chi Sun Poon
Pretreatment-induced initial hydration would significantly influence subsequent carbonation. However, the evolution of microstructure and performance resulting from the synergistic action of hydration and carbonation remains systematically unexplored. This study investigates carbonation kinetics, microstructure and micro/macro mechanical properties of carbonated cement pastes (CCPs) under the synergistic action of initial hydration and subsequent carbonation, while elucidating the underlying mechanisms. The results revealed that unhydrated cement exhibited a peak carbonation rate of 0.65 W/g, increasing by approximately 83% when the cement underwent an 8 h of initial curing, demonstrating the enhancement in the carbonation reactivity due to initial hydration. However, the carbonation efficiency of CCPs increased initially and then decreased as initial hydration extended. This trend emerged because initial hydration enhanced carbonation reactivity, whereas excessive hydration concurrently obstructed CO2 transport. Furthermore, optimal initial hydration was essential for the synergistic interaction between hydration and carbonation, resulting in reduced porosity and a more homogeneous microstructure, as well as improved mechanical properties. These findings underscore the need to carefully consider the synergistic action of initial hydration and subsequent carbonation when designing pretreatment protocols.
{"title":"Insights into the synergistic action of initial hydration and subsequent carbonation of Portland cement","authors":"Jionghuang He, Yingliang Zhao, Yong Tao, Peiliang Shen, Chi Sun Poon","doi":"10.1016/j.cemconcomp.2025.105924","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.105924","url":null,"abstract":"Pretreatment-induced initial hydration would significantly influence subsequent carbonation. However, the evolution of microstructure and performance resulting from the synergistic action of hydration and carbonation remains systematically unexplored. This study investigates carbonation kinetics, microstructure and micro/macro mechanical properties of carbonated cement pastes (CCPs) under the synergistic action of initial hydration and subsequent carbonation, while elucidating the underlying mechanisms. The results revealed that unhydrated cement exhibited a peak carbonation rate of 0.65 W/g, increasing by approximately 83% when the cement underwent an 8 h of initial curing, demonstrating the enhancement in the carbonation reactivity due to initial hydration. However, the carbonation efficiency of CCPs increased initially and then decreased as initial hydration extended. This trend emerged because initial hydration enhanced carbonation reactivity, whereas excessive hydration concurrently obstructed CO<sub>2</sub> transport. Furthermore, optimal initial hydration was essential for the synergistic interaction between hydration and carbonation, resulting in reduced porosity and a more homogeneous microstructure, as well as improved mechanical properties. These findings underscore the need to carefully consider the synergistic action of initial hydration and subsequent carbonation when designing pretreatment protocols.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
By virtue of its superior strength, high toughness, and low porosity, ultra-high-performance concrete (UHPC) has a wide range of application prospects in construction engineering. However, the interfacial transition zone (ITZ) formed between the cementitious matrix and steel fiber seriously restricts the steel fiber’s strength utilization rate in UHPC. Hence, in this work, graphene oxide (GO) is employed to be coated on the steel fiber surface to strengthen the UHPC. The results demonstrate that through a three-step GO coating approach, the roughness and hydrophilicity of the steel fiber surface can be enhanced by about 280.6% and 40.6% compared with plain steel fiber. The coated GO can provide pore-infilling and nucleation effects during the hydration processes of the UHPC, thus decreasing the porosity by 37.5% compared with non-GO reinforcement. After the three-step coating treatment, the compressive and bending strength of the coated-GO reinforced UHPC is enhanced by 33.7% and 26.2%, respectively. The molecular dynamic simulation results further reveal that benefiting from the crack-bridging effects of the coated GO, the interface between the steel fiber surface and cement matrix is prone to a ductile failure, with the failure energy of the C-S-H composites increasing by about 320%-1340%. The findings advanced by this work can enhance the understanding of nano-cement technology and promote the potential application of the GO-coated fiber to generate high-performance UHPC.
{"title":"Mechanical Performance Enhancement of UHPC Via ITZ Improvement Using Graphene Oxide-Coated Steel Fibers","authors":"Yuan Gao, Zhangjianing Cheng, Jiajian Yu, Xiaonong Guo, Yanming Liu, Weiqiang Chen","doi":"10.1016/j.cemconcomp.2025.105931","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.105931","url":null,"abstract":"By virtue of its superior strength, high toughness, and low porosity, ultra-high-performance concrete (UHPC) has a wide range of application prospects in construction engineering. However, the interfacial transition zone (ITZ) formed between the cementitious matrix and steel fiber seriously restricts the steel fiber’s strength utilization rate in UHPC. Hence, in this work, graphene oxide (GO) is employed to be coated on the steel fiber surface to strengthen the UHPC. The results demonstrate that through a three-step GO coating approach, the roughness and hydrophilicity of the steel fiber surface can be enhanced by about 280.6% and 40.6% compared with plain steel fiber. The coated GO can provide pore-infilling and nucleation effects during the hydration processes of the UHPC, thus decreasing the porosity by 37.5% compared with non-GO reinforcement. After the three-step coating treatment, the compressive and bending strength of the coated-GO reinforced UHPC is enhanced by 33.7% and 26.2%, respectively. The molecular dynamic simulation results further reveal that benefiting from the crack-bridging effects of the coated GO, the interface between the steel fiber surface and cement matrix is prone to a ductile failure, with the failure energy of the C-S-H composites increasing by about 320%-1340%. The findings advanced by this work can enhance the understanding of nano-cement technology and promote the potential application of the GO-coated fiber to generate high-performance UHPC.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The application of binder consisting of limestone, calcined clay and cement (LC3) promotes the development of low-carbon engineering cementitious composites (ECC). In order to improve the comprehensive properties of LC3-ECC, this paper investigates the feasibility of using nano CaCO3 (NC) to replace the limestone powder up to 20% for LC3-ECC preparation through rheology and mechanical tests along with the micro-design calculation and microstructure analysis. Results indicate that the yield stress and plastic viscosity of LC3-ECC are largely improved with increasing NC replacement rate. Meanwhile, the compressive, flexural and tensile strengths of LC3-ECC with NC raise firstly and then decline, while the strengths are maximum at NC replacement rate of 5% but the tensile strain capacity remains at 2.3%. The hydration promotion effect and pore structure refinement effect of NC particles improve the mechanical strength of LC3-ECC, but the performance degradation occurs when the replacement rate of the NC exceeds 10%. In micromechanics, the fibre bridging stress of LC3-ECC reinforced by NC with replacement rate of 5% decreases by 18.5% compared to that of without NC, but it grows with the increasing NC replacement rate. In combination with fresh, hardened and microstructure behaviour, LC3-ECC exhibits the optimum mechanical behaviour with the NC replacement rate of 10%–15%.
{"title":"Rheology and mechanical properties of limestone calcined clay based engineered cementitious composites with nano CaCO3","authors":"Yuting Wang, Meng Chen, Tong Zhang, Mingzhong Zhang","doi":"10.1016/j.cemconcomp.2025.105923","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.105923","url":null,"abstract":"The application of binder consisting of limestone, calcined clay and cement (LC<sup>3</sup>) promotes the development of low-carbon engineering cementitious composites (ECC). In order to improve the comprehensive properties of LC<sup>3</sup>-ECC, this paper investigates the feasibility of using nano CaCO<sub>3</sub> (NC) to replace the limestone powder up to 20% for LC<sup>3</sup>-ECC preparation through rheology and mechanical tests along with the micro-design calculation and microstructure analysis. Results indicate that the yield stress and plastic viscosity of LC<sup>3</sup>-ECC are largely improved with increasing NC replacement rate. Meanwhile, the compressive, flexural and tensile strengths of LC<sup>3</sup>-ECC with NC raise firstly and then decline, while the strengths are maximum at NC replacement rate of 5% but the tensile strain capacity remains at 2.3%. The hydration promotion effect and pore structure refinement effect of NC particles improve the mechanical strength of LC<sup>3</sup>-ECC, but the performance degradation occurs when the replacement rate of the NC exceeds 10%. In micromechanics, the fibre bridging stress of LC<sup>3</sup>-ECC reinforced by NC with replacement rate of 5% decreases by 18.5% compared to that of without NC, but it grows with the increasing NC replacement rate. In combination with fresh, hardened and microstructure behaviour, LC<sup>3</sup>-ECC exhibits the optimum mechanical behaviour with the NC replacement rate of 10%–15%.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142935162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-07DOI: 10.1016/j.cemconcomp.2025.105925
Dingqiang Fan, Jian-Xin Lu, Xue-Sen Lv, Takafumi Noguchi, Rui Yu, Chi Sun Poon
This study introduces a novel strategy for carbon capture and utilization by incorporating CO2 into foams to develop CO2 foam concrete (CFC) with high performance. A conceptual design approach for CFC was first proposed by incorporating tailor-made CO2 foam bubbles into an optimized cement-based paste. The engineered CO2 foam exhibited fine size and good stability, but increasing CO2 concentration decreased stability. Then, the CO2 foam was used to fabricate CFC with high strength (about twice that of normal foam concrete at a similar density), excellent durability (comparable to normal concrete), and low thermal conductivity. Moreover, it was demonstrated that CO2 foam induced positive internal carbonation effects to further enhance the CFC performance. These effects included promoting cement hydration efficiency and generating CaCO3 on the foam wall for strength enhancement. Also, the rational use of CO2 foams optimized the CFC pore structures, including reducing porosity, refining pore size, and improving pore uniformity. The CFC exhibited exceptional carbon capture, sequestering 87 kg of CO2 per m3 of concrete by internal and external carbonations (active carbon reduction), and could reduce electricity consumption and the corresponding carbon emissions (indirect carbon reduction). This innovative material offers a promising pathway towards sustainable construction and carbon neutrality.
{"title":"Carbon capture and storage CO2 foam concrete towards higher performance: Design, preparation and characteristics","authors":"Dingqiang Fan, Jian-Xin Lu, Xue-Sen Lv, Takafumi Noguchi, Rui Yu, Chi Sun Poon","doi":"10.1016/j.cemconcomp.2025.105925","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.105925","url":null,"abstract":"This study introduces a novel strategy for carbon capture and utilization by incorporating CO<sub>2</sub> into foams to develop CO<sub>2</sub> foam concrete (CFC) with high performance. A conceptual design approach for CFC was first proposed by incorporating tailor-made CO<sub>2</sub> foam bubbles into an optimized cement-based paste. The engineered CO<sub>2</sub> foam exhibited fine size and good stability, but increasing CO<sub>2</sub> concentration decreased stability. Then, the CO<sub>2</sub> foam was used to fabricate CFC with high strength (about twice that of normal foam concrete at a similar density), excellent durability (comparable to normal concrete), and low thermal conductivity. Moreover, it was demonstrated that CO<sub>2</sub> foam induced positive internal carbonation effects to further enhance the CFC performance. These effects included promoting cement hydration efficiency and generating CaCO<sub>3</sub> on the foam wall for strength enhancement. Also, the rational use of CO<sub>2</sub> foams optimized the CFC pore structures, including reducing porosity, refining pore size, and improving pore uniformity. The CFC exhibited exceptional carbon capture, sequestering 87 kg of CO<sub>2</sub> per m<sup>3</sup> of concrete by internal and external carbonations (active carbon reduction), and could reduce electricity consumption and the corresponding carbon emissions (indirect carbon reduction). This innovative material offers a promising pathway towards sustainable construction and carbon neutrality.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"203 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142935161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-06DOI: 10.1016/j.cemconcomp.2025.105922
Yanjie Tang, Katrin Schollbach, Sieger van der Laan, Wei Chen
This study investigates the hydration of basic oxygen furnace (BOF) slag activated by dipotassium hydrogen phosphate (DKP) up to 3 wt.%. The findings reveal that DKP-activated BOF slag pastes exhibit improved strength, leaching behavior, and carbonation resistance. DKP-activated BOF slag pastes facilitate the completion of the main exothermic reaction within 3 days. Increasing DKP from 1 to 3 wt.% extends the induction period while enhancing overall hydration heat. This is attributed to the consumption of C2S and brownmillerite, and the formation of hydrogarnet, C-S-H gel, and layered double hydroxides (LDHs). Concomitantly, porosity reduces from 40.73 to 22.36%, leading to significant strength gaining from 1.9 to 42.5 MPa over 28 days. Moreover, DKP-containing samples exhibit satisfactory carbonation resistance and limited heavy metal leaching, complying with the Dutch Soil Quality Decree (SQD). The study highlights the potential of phosphate activation to enhance the durability and environmental performance of BOF slag-based materials.
{"title":"Activation of BOF Slag with Dipotassium Hydrogen Phosphate: Enhancing Hydration, Carbonation Resistance, and Heavy Metal Leaching","authors":"Yanjie Tang, Katrin Schollbach, Sieger van der Laan, Wei Chen","doi":"10.1016/j.cemconcomp.2025.105922","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.105922","url":null,"abstract":"This study investigates the hydration of basic oxygen furnace (BOF) slag activated by dipotassium hydrogen phosphate (DKP) up to 3 wt.%. The findings reveal that DKP-activated BOF slag pastes exhibit improved strength, leaching behavior, and carbonation resistance. DKP-activated BOF slag pastes facilitate the completion of the main exothermic reaction within 3 days. Increasing DKP from 1 to 3 wt.% extends the induction period while enhancing overall hydration heat. This is attributed to the consumption of C<sub>2</sub>S and brownmillerite, and the formation of hydrogarnet, C-S-H gel, and layered double hydroxides (LDHs). Concomitantly, porosity reduces from 40.73 to 22.36%, leading to significant strength gaining from 1.9 to 42.5 MPa over 28 days. Moreover, DKP-containing samples exhibit satisfactory carbonation resistance and limited heavy metal leaching, complying with the Dutch Soil Quality Decree (SQD). The study highlights the potential of phosphate activation to enhance the durability and environmental performance of BOF slag-based materials.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142928992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-06DOI: 10.1016/j.cemconcomp.2025.105927
Qi Zhang, Pan Feng, Xuyan Shen, Yuxi Cai, Houru Zhen, Zhichao Liu
Maximizing the use of solid wastes to replace energy-intensive cement while maintaining the comparable mechanical properties is a promising strategy for developing negative carbon building materials. In this paper, full steel slag/carbide slag blocks were prepared by pressing and subsequent carbonation to enhance mechanical properties and capture CO2. The evolution of carbonation degree and compressive strength with varying liquid to solid ratios and carbonation durations were characterized, followed by a comparative analysis of carbonation strengthening mechanisms. The results show that carbonation significantly improves compressive strengths, exhibiting a linear relationship between carbonation degree and compressive strength. The maximum carbonation degrees and compressive strengths achieved were 24.56% and 79.68 MPa for full steel slag blocks, and 64.46%, 44.64 MPa for full carbide slag blocks, respectively. Although the maximum carbonation degree of full steel slag blocks is only about one-third of that of the full carbide slag blocks, their superior compressive strength can be attributed to denser microstructures, stronger bonding properties between steel slag particles and carbonated products, and a larger effective elastic modulus. This study provides a new insight into the carbonation strengthening mechanisms based on the inherent properties of different materials and introduces a novel concept for creating high-performance, eco-friendly building materials.
{"title":"Comparative Analysis of Carbonation Strengthening Mechanisms in Full Solid Waste Materials: Steel Slag vs. Carbide Slag","authors":"Qi Zhang, Pan Feng, Xuyan Shen, Yuxi Cai, Houru Zhen, Zhichao Liu","doi":"10.1016/j.cemconcomp.2025.105927","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.105927","url":null,"abstract":"Maximizing the use of solid wastes to replace energy-intensive cement while maintaining the comparable mechanical properties is a promising strategy for developing negative carbon building materials. In this paper, full steel slag/carbide slag blocks were prepared by pressing and subsequent carbonation to enhance mechanical properties and capture CO<sub>2</sub>. The evolution of carbonation degree and compressive strength with varying liquid to solid ratios and carbonation durations were characterized, followed by a comparative analysis of carbonation strengthening mechanisms. The results show that carbonation significantly improves compressive strengths, exhibiting a linear relationship between carbonation degree and compressive strength. The maximum carbonation degrees and compressive strengths achieved were 24.56% and 79.68 MPa for full steel slag blocks, and 64.46%, 44.64 MPa for full carbide slag blocks, respectively. Although the maximum carbonation degree of full steel slag blocks is only about one-third of that of the full carbide slag blocks, their superior compressive strength can be attributed to denser microstructures, stronger bonding properties between steel slag particles and carbonated products, and a larger effective elastic modulus. This study provides a new insight into the carbonation strengthening mechanisms based on the inherent properties of different materials and introduces a novel concept for creating high-performance, eco-friendly building materials.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142935085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-06DOI: 10.1016/j.cemconcomp.2025.105921
Brahim Mazian, Giana Almeida, Nils Frantz, Patrick Perré
Lime-hemp concrete (LHC) emerges as a sustainable building material due to its low embodied energy, carbon storage capabilities, and interesting properties for both winter and summer comfort. However, a comprehensive understanding of its moisture behavior is pivotal for its development and application in construction. This study investigates the moisture sorption behavior and isotherm characteristics of LHC across four formulations varying in density (321–478 kg/m³) and binder/particle weight ratios (BP = 1 and 2). Using a strict equilibrium criterion, over 3000 hours of Dynamic Vapor Sorption (DVS), experiments revealed some formulations failed to reach equilibrium during adsorption at RH levels above 60%, indicating irreversible processes characterized by offsets in equilibrium moisture content (EMC) at 0% RH after a complete cycle. These phenomena were attributed to insufficient water availability during mixing and/or excessive compaction. Formulations with a higher weight ratio (B/P=2) and significant compaction, such as BP2_420, exhibited the highest desorption offset (7.5% EMC), while those with a lower B/P weight ratio (B/P=1), such as BP1_379, showed reduced offsets below 2%, due to better water distribution. The study also showed that reversible sorption behavior, corrected for offsets, could be accurately described using the Guggenheim-Anderson-de Boer (GAB) model. Finally, the rule of mixtures reliably predicted sorption isotherms by combining the GAB parameters of hemp shive particles and binders, with deviations limited to a maximum error of 2.3%.
{"title":"In-depth Analysis of Lime-Hemp Concrete and Water Vapor Interactions: Effect of water default and prediction of the sorption behavior","authors":"Brahim Mazian, Giana Almeida, Nils Frantz, Patrick Perré","doi":"10.1016/j.cemconcomp.2025.105921","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.105921","url":null,"abstract":"Lime-hemp concrete (LHC) emerges as a sustainable building material due to its low embodied energy, carbon storage capabilities, and interesting properties for both winter and summer comfort. However, a comprehensive understanding of its moisture behavior is pivotal for its development and application in construction. This study investigates the moisture sorption behavior and isotherm characteristics of LHC across four formulations varying in density (321–478 kg/m³) and binder/particle weight ratios (BP = 1 and 2). Using a strict equilibrium criterion, over 3000 hours of Dynamic Vapor Sorption (DVS), experiments revealed some formulations failed to reach equilibrium during adsorption at RH levels above 60%, indicating irreversible processes characterized by offsets in equilibrium moisture content (EMC) at 0% RH after a complete cycle. These phenomena were attributed to insufficient water availability during mixing and/or excessive compaction. Formulations with a higher weight ratio (B/P=2) and significant compaction, such as BP2_420, exhibited the highest desorption offset (7.5% EMC), while those with a lower B/P weight ratio (B/P=1), such as BP1_379, showed reduced offsets below 2%, due to better water distribution. The study also showed that reversible sorption behavior, corrected for offsets, could be accurately described using the Guggenheim-Anderson-de Boer (GAB) model. Finally, the rule of mixtures reliably predicted sorption isotherms by combining the GAB parameters of hemp shive particles and binders, with deviations limited to a maximum error of 2.3%.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142928994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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