Pub Date : 2024-11-13DOI: 10.1016/j.conbuildmat.2024.138933
Yining Ding , Wei Guo , Dongsheng Li , F. Pacheco-Torgal
This study explores the possibilities of the structural use of macro polyoxymethylene (POM) fibers in concrete and investigates the toughness and self-sensing performance to crack opening in POM fiber reinforced concrete (FRC) under bending. The residual flexural strengths of POM FRC are compared with macro polypropylene (PP) FRC with the same size and dosage of PP fiber. Macro steel fibers and nano carbon powder are employed as both conductive and structural materials to realize the self-sensing capabilities for monitoring crack development and to increase the toughness in POM FRC under bending. The results show that the addition of POM fibers significantly enhances the post-cracking toughness of concrete. Furthermore, the hybrid use of macro POM fibers and steel fibers exhibits a positive synergetic effect on the residual flexural strengths of concrete; even the mixed use with low dosages of various macro fibers may cause deflection hardening and multiple cracks are observed. The addition of nano carbon powder increases the slope of fractional change in resistance (FCR) of concrete beams. The FCR and CMOD for single cracking beams show an almost linear relationship, while the FCR and CMOD for multiple cracking beams follow a first-order exponential relationship.
{"title":"Exploring the effect of polyoxymethylene fiber on concrete toughness and self-sensing capability of concrete cracking under bending","authors":"Yining Ding , Wei Guo , Dongsheng Li , F. Pacheco-Torgal","doi":"10.1016/j.conbuildmat.2024.138933","DOIUrl":"10.1016/j.conbuildmat.2024.138933","url":null,"abstract":"<div><div>This study explores the possibilities of the structural use of macro polyoxymethylene (POM) fibers in concrete and investigates the toughness and self-sensing performance to crack opening in POM fiber reinforced concrete (FRC) under bending. The residual flexural strengths of POM FRC are compared with macro polypropylene (PP) FRC with the same size and dosage of PP fiber. Macro steel fibers and nano carbon powder are employed as both conductive and structural materials to realize the self-sensing capabilities for monitoring crack development and to increase the toughness in POM FRC under bending. The results show that the addition of POM fibers significantly enhances the post-cracking toughness of concrete. Furthermore, the hybrid use of macro POM fibers and steel fibers exhibits a positive synergetic effect on the residual flexural strengths of concrete; even the mixed use with low dosages of various macro fibers may cause deflection hardening and multiple cracks are observed. The addition of nano carbon powder increases the slope of fractional change in resistance (FCR) of concrete beams. The FCR and CMOD for single cracking beams show an almost linear relationship, while the FCR and CMOD for multiple cracking beams follow a first-order exponential relationship.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"454 ","pages":"Article 138933"},"PeriodicalIF":7.4,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651208","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}
Pub Date : 2024-11-13DOI: 10.1016/j.conbuildmat.2024.139148
Lei Yang , Zhuo Liu , Pengjie Rong , Shuqiong Luo , Xuemao Guan , Jianping Zhu , Xiangming Zhou , Songhui Liu , Genshen Li
This study investigates the effects of magnesium sulfate (MgSO4) addition on the carbonation efficiency and mechanical properties of low-calcium CO2-sequestering cementitious material (LCC), which is prepared by calcining a mixture of 78.2% limestone and 21.8% sandstone at 1275 °C for 2 h. LCC samples were prepared with varying concentrations of MgSO4 solution (0, 0.5, 1, 2, and 3 mol/L) and subjected to CO2 curing for 24 h. The carbonation behavior, compressive strength, and microstructural characteristics were examined using XRD, TGA, FT-IR, SEM, and LF NMR techniques in combination. Results demonstrate that the addition of MgSO4 significantly influences the carbonation process and mechanical performance of LCC. Optimum performance was achieved after subjecting the paste prepared with LCC at a concentration of 0.5 mol/L MgSO4 to a carbonation period lasting 24 h. This resulted in a notable increase in compressive strength by approximately 28% (145 MPa) compared to control samples along with an observed enhancement in CO2 uptake by around 4%. Microstructural analysis reveals that the inclusion of MgSO4 promoted the formation of more stable carbonate phases such as Mg-calcite and vaterite while also enhancing silica gel polymerization within the matrix structure of LCC materials. Additionally, it was found excessive concentrations (>1 mol/L) of MgSO4 led to decreased carbonation efficiency and reduced strength due to gypsum formation as well as limited pore water availability. This study provides valuable insights into optimizing the carbonation process of LCC materials while demonstrating the potential efficacy of MgSO4 as an effective additive for enhancing the performance of low-carbon CO2-sequestering cementitious materials.
{"title":"Optimizing carbonation efficiency and mechanical properties of low-calcium cementitious materials with MgSO4 addition","authors":"Lei Yang , Zhuo Liu , Pengjie Rong , Shuqiong Luo , Xuemao Guan , Jianping Zhu , Xiangming Zhou , Songhui Liu , Genshen Li","doi":"10.1016/j.conbuildmat.2024.139148","DOIUrl":"10.1016/j.conbuildmat.2024.139148","url":null,"abstract":"<div><div>This study investigates the effects of magnesium sulfate (MgSO<sub>4</sub>) addition on the carbonation efficiency and mechanical properties of low-calcium CO<sub>2</sub>-sequestering cementitious material (LCC), which is prepared by calcining a mixture of 78.2% limestone and 21.8% sandstone at 1275 °C for 2 h. LCC samples were prepared with varying concentrations of MgSO<sub>4</sub> solution (0, 0.5, 1, 2, and 3 mol/L) and subjected to CO<sub>2</sub> curing for 24 h. The carbonation behavior, compressive strength, and microstructural characteristics were examined using XRD, TGA, FT-IR, SEM, and LF NMR techniques in combination. Results demonstrate that the addition of MgSO<sub>4</sub> significantly influences the carbonation process and mechanical performance of LCC. Optimum performance was achieved after subjecting the paste prepared with LCC at a concentration of 0.5 mol/L MgSO<sub>4</sub> to a carbonation period lasting 24 h. This resulted in a notable increase in compressive strength by approximately 28% (145 MPa) compared to control samples along with an observed enhancement in CO<sub>2</sub> uptake by around 4%. Microstructural analysis reveals that the inclusion of MgSO<sub>4</sub> promoted the formation of more stable carbonate phases such as Mg-calcite and vaterite while also enhancing silica gel polymerization within the matrix structure of LCC materials. Additionally, it was found excessive concentrations (>1 mol/L) of MgSO<sub>4</sub> led to decreased carbonation efficiency and reduced strength due to gypsum formation as well as limited pore water availability. This study provides valuable insights into optimizing the carbonation process of LCC materials while demonstrating the potential efficacy of MgSO<sub>4</sub> as an effective additive for enhancing the performance of low-carbon CO<sub>2</sub>-sequestering cementitious materials.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"454 ","pages":"Article 139148"},"PeriodicalIF":7.4,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651288","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}
Phase change materials (PCMs) can absorb and release significant amount of latent heat, making them highly promising for applications in the thermal insulation field. As a common and inexpensive PCMs, solid paraffin wax (PW) has high thermal conductivity but is prone to leak. Therefore, it is of significant to combine it with materials that have low thermal conductivity and good encapsulation properties. Herein, ethylene propylene diene monomer rubber (EPDM) was utilized as encapsulation material for PW, and the EPDM/PW foam was prepared using supercritical CO2. In addition, SiO2 aerogels were added to improve foaming behavior and reduce thermal conductivity. The results indicated that the EPDM network structure could completely encapsulated the PW, and the phase change foam exhibited a uniform closed-cell structure with a minimum density of 0.05 g/cm3. The addition of SiO2 aerogel reduced the thermal conductivity to 0.046 W/(m·K). Simultaneously, the heating and cooling rates of the phase change foam were monitored using an infrared imager. Compared to EPDM foam, the time required to heat to 52 °C increased by 450 s, the surface temperature decreased by 3 °C at constant temperature, and the time to cool down to 20 °C increased by 900 s. These results indicate that the foam possesses good thermal insulation and energy storage properties. Therefore, the EPDM/PW phase change foam has promising applications in pipeline insulation, building exterior wall, etc.
{"title":"Development of flexible lightweight EPDM/PW energy storage foams with low thermal conductivity by supercritical CO2","authors":"Shaokang Song, Zhen Yu, Xin Zhang, Shibao Wen, Yingjie Zhao, Zhen Xiu Zhang","doi":"10.1016/j.conbuildmat.2024.139042","DOIUrl":"10.1016/j.conbuildmat.2024.139042","url":null,"abstract":"<div><div>Phase change materials (PCMs) can absorb and release significant amount of latent heat, making them highly promising for applications in the thermal insulation field. As a common and inexpensive PCMs, solid paraffin wax (PW) has high thermal conductivity but is prone to leak. Therefore, it is of significant to combine it with materials that have low thermal conductivity and good encapsulation properties. Herein, ethylene propylene diene monomer rubber (EPDM) was utilized as encapsulation material for PW, and the EPDM/PW foam was prepared using supercritical CO<sub>2</sub>. In addition, SiO<sub>2</sub> aerogels were added to improve foaming behavior and reduce thermal conductivity. The results indicated that the EPDM network structure could completely encapsulated the PW, and the phase change foam exhibited a uniform closed-cell structure with a minimum density of 0.05 g/cm<sup>3</sup>. The addition of SiO<sub>2</sub> aerogel reduced the thermal conductivity to 0.046 W/(m·K). Simultaneously, the heating and cooling rates of the phase change foam were monitored using an infrared imager. Compared to EPDM foam, the time required to heat to 52 °C increased by 450 s, the surface temperature decreased by 3 °C at constant temperature, and the time to cool down to 20 °C increased by 900 s. These results indicate that the foam possesses good thermal insulation and energy storage properties. Therefore, the EPDM/PW phase change foam has promising applications in pipeline insulation, building exterior wall, etc.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"454 ","pages":"Article 139042"},"PeriodicalIF":7.4,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651290","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}
Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139111
Baifa Zhang , Faheem Muhammad , Ting Yu , Mohammad Fahimizadeh , Muhammad Arshad Shehzad Hassan , Jingkang Liang , Xun'an Ning , Peng Yuan
The increasing demand for sustainable construction materials has led to the exploration of iron tailings (ITs) as supplementary cementitious materials (SCMs) in Limestone Calcined Clay Cement (LC3). This study investigates the effects of varying ITs content in LC3 on compressive strength, microstructure, and environmental impact. Replacing 28 % of LC3 with ITs resulted in a 42 MPa compressive strength after 28 days, comparable to ordinary Portland cement (OPC), while reducing OPC content by 50 %. Microstructural analysis revealed that ITs contributed to the formation of additional C-(A)-S-H gel, enhancing the mechanical properties of the cement matrix. The findings also showed that concentrations of Zn (0.003–0.094 mg/L), Pb (0.002–0.090 mg/L), Cu (0.005–0.018 mg/L), Mn (0.115–0.712 mg/L), Ni (0.011–0.021 mg/L) in the leachates of LC3 containing ITs were below the critical limits for surface water and groundwater. Moreover, the life cycle assessment (LCA) demonstrated significant reductions in global warming potential (43.6 %), energy consumption (37.2 %), and cost (35.5 %). This study provides an innovative solution for waste utilization and environmentally friendly cement production.
随着对可持续建筑材料需求的不断增长，人们开始探索在石灰石煅烧粘土水泥（LC3）中使用铁尾矿作为补充胶凝材料（SCMs）。本研究调查了 LC3 中不同 ITs 含量对抗压强度、微观结构和环境影响的影响。用 ITs 替代 LC3 中 28% 的 ITs 后，28 天后的抗压强度达到 42 兆帕，与普通波特兰水泥（OPC）相当，而 OPC 的含量减少了 50%。微观结构分析表明，ITs 有助于形成额外的 C-(A)-S-H 凝胶，从而提高水泥基体的机械性能。研究结果还表明，含有 ITs 的 LC3 浸出液中的锌（0.003-0.094 mg/L）、铅（0.002-0.090 mg/L）、铜（0.005-0.018 mg/L）、锰（0.115-0.712 mg/L）、镍（0.011-0.021 mg/L）浓度低于地表水和地下水的临界限值。此外，生命周期评估（LCA）显示，全球升温潜能值（43.6%）、能耗（37.2%）和成本（35.5%）均显著降低。这项研究为废物利用和环保型水泥生产提供了一种创新解决方案。
{"title":"Harnessing iron tailings as supplementary cementitious materials in Limestone Calcined Clay Cement (LC3): An innovative approach towards sustainable construction","authors":"Baifa Zhang , Faheem Muhammad , Ting Yu , Mohammad Fahimizadeh , Muhammad Arshad Shehzad Hassan , Jingkang Liang , Xun'an Ning , Peng Yuan","doi":"10.1016/j.conbuildmat.2024.139111","DOIUrl":"10.1016/j.conbuildmat.2024.139111","url":null,"abstract":"<div><div>The increasing demand for sustainable construction materials has led to the exploration of iron tailings (ITs) as supplementary cementitious materials (SCMs) in Limestone Calcined Clay Cement (LC<sup>3</sup>). This study investigates the effects of varying ITs content in LC<sup>3</sup> on compressive strength, microstructure, and environmental impact. Replacing 28 % of LC<sup>3</sup> with ITs resulted in a 42 MPa compressive strength after 28 days, comparable to ordinary Portland cement (OPC), while reducing OPC content by 50 %. Microstructural analysis revealed that ITs contributed to the formation of additional C-(A)-S-H gel, enhancing the mechanical properties of the cement matrix. The findings also showed that concentrations of Zn (0.003–0.094 mg/L), Pb (0.002–0.090 mg/L), Cu (0.005–0.018 mg/L), Mn (0.115–0.712 mg/L), Ni (0.011–0.021 mg/L) in the leachates of LC<sup>3</sup> containing ITs were below the critical limits for surface water and groundwater. Moreover, the life cycle assessment (LCA) demonstrated significant reductions in global warming potential (43.6 %), energy consumption (37.2 %), and cost (35.5 %). This study provides an innovative solution for waste utilization and environmentally friendly cement production.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"453 ","pages":"Article 139111"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658890","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}
Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139086
Hao Cheng , Minfei Liang
Monitoring of gradual increase in elastic modulus of concrete over time is crucial for designing structures exposed to early age loading and predicting long-term deformations, such as creep. Two primary methods are used to assess elastic modulus: the static method, involving compression tests, and the dynamic method, utilizing approaches like EMM-ARM (E-modulus Measurement through Ambient Response Method), impact-echo, and ultrasonic approach. The static method, although destructive, yields the static or secant modulus, directly applicable for structural design. However, it cannot be utilized to track changes in elastic modulus within the existing structure caused by factors such as hydration, freeze-thaw, or chemical attack. In contrast, the non-destructive dynamic method can monitor these changes in the existing structure. Yet, the elastic modulus obtained through this method, known as the dynamic elastic modulus, represents the initial tangent modulus and is generally higher than the static modulus. To estimate the static elastic modulus through the non-destructive ultrasonic approach, we propose a new signal processing technique using direct wave interferometry (DWI) in this study. To validate the elastic modulus estimated through this technique, embeddable ultrasonic sensors are installed in the specimen within the temperature stress testing machine (TSTM). The experimental results show that the elastic modulus derived from the newly proposed DWI-based ultrasonic approach consistently provides more accurate estimates of the static elastic modulus compared to the UPV-based dynamic elastic modulus. The relative errors between the DWI-based and compression test-based elastic moduli on 7-day is 2.6 %. This approach also enables the tracking of static elastic modulus changes due to freeze-thaw cycles or chemical attacks.
{"title":"Real-time monitoring of static elastic modulus evolution in hardening concrete through longitudinal-wave velocity changes retrieved by the stretching technique","authors":"Hao Cheng , Minfei Liang","doi":"10.1016/j.conbuildmat.2024.139086","DOIUrl":"10.1016/j.conbuildmat.2024.139086","url":null,"abstract":"<div><div>Monitoring of gradual increase in elastic modulus of concrete over time is crucial for designing structures exposed to early age loading and predicting long-term deformations, such as creep. Two primary methods are used to assess elastic modulus: the static method, involving compression tests, and the dynamic method, utilizing approaches like EMM-ARM (E-modulus Measurement through Ambient Response Method), impact-echo, and ultrasonic approach. The static method, although destructive, yields the static or secant modulus, directly applicable for structural design. However, it cannot be utilized to track changes in elastic modulus within the existing structure caused by factors such as hydration, freeze-thaw, or chemical attack. In contrast, the non-destructive dynamic method can monitor these changes in the existing structure. Yet, the elastic modulus obtained through this method, known as the dynamic elastic modulus, represents the initial tangent modulus and is generally higher than the static modulus. To estimate the static elastic modulus through the non-destructive ultrasonic approach, we propose a new signal processing technique using direct wave interferometry (DWI) in this study. To validate the elastic modulus estimated through this technique, embeddable ultrasonic sensors are installed in the specimen within the temperature stress testing machine (TSTM). The experimental results show that the elastic modulus derived from the newly proposed DWI-based ultrasonic approach consistently provides more accurate estimates of the static elastic modulus compared to the UPV-based dynamic elastic modulus. The relative errors between the DWI-based and compression test-based elastic moduli on 7-day is 2.6 %. This approach also enables the tracking of static elastic modulus changes due to freeze-thaw cycles or chemical attacks.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"453 ","pages":"Article 139086"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659484","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}
Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139075
Changqing Wang , Zhicheng Du , Zhiyu Zhang , Youchao Zhang , Zhiming Ma
In the field of green building materials, the development of high-toughness recycled aggregate concrete (HTRAC) is crucial for sustainable construction. This study employs in-situ 4D CT technology to observe the meso-structural changes in HTRAC under uniaxial loading, with a focus on the spatial distribution of pores and fibers, as well as the formation and evolution of cracks. Additionally, digital volume correlation (DVC) is utilized to visually analyze the internal strain environment. The results demonstrate the material's heterogeneity and its localized effects on stress/strain distribution, revealing significant differences in crack morphology and strain distribution between recycled coarse aggregate (RCA) interfaces and fiber regions. The inclusion of microsteel fibers enhances crack resistance and toughness, resulting in an increase of the toughness index by 114 %, effectively dispersing stress and impeding crack propagation, thereby improving the material's overall structural performance. A damage evolution model, derived from strain statistical analysis during the HTRAC failure process, offers theoretical and technical support for the design and application of HTRAC in construction.
{"title":"In-situ 4D CT scanning and digital volume correlation for 3D kinematic field analysis in high-toughness recycled aggregate concrete","authors":"Changqing Wang , Zhicheng Du , Zhiyu Zhang , Youchao Zhang , Zhiming Ma","doi":"10.1016/j.conbuildmat.2024.139075","DOIUrl":"10.1016/j.conbuildmat.2024.139075","url":null,"abstract":"<div><div>In the field of green building materials, the development of high-toughness recycled aggregate concrete (HTRAC) is crucial for sustainable construction. This study employs in-situ 4D CT technology to observe the meso-structural changes in HTRAC under uniaxial loading, with a focus on the spatial distribution of pores and fibers, as well as the formation and evolution of cracks. Additionally, digital volume correlation (DVC) is utilized to visually analyze the internal strain environment. The results demonstrate the material's heterogeneity and its localized effects on stress/strain distribution, revealing significant differences in crack morphology and strain distribution between recycled coarse aggregate (RCA) interfaces and fiber regions. The inclusion of microsteel fibers enhances crack resistance and toughness, resulting in an increase of the toughness index by 114 %, effectively dispersing stress and impeding crack propagation, thereby improving the material's overall structural performance. A damage evolution model, derived from strain statistical analysis during the HTRAC failure process, offers theoretical and technical support for the design and application of HTRAC in construction.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"453 ","pages":"Article 139075"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659229","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}
Solid waste binders have been accepted for their eco-friendliness and good mechanical properties. The effect of alkaline activators on binder hydration process is currently a hot research topic in this field. However, there is a lack of systematic summary and analysis on how to utilize the synergistic cooperation among various ions to promote the hydration reaction. This paper designs a scientific system using the chemical composition from gypsum, municipal solid waste incineration fly ash and steel slag, highlighting the differences of alkaline activations on low-hydration coal gasification slag. Results show that replacing 40 % of blast furnace slag with coal gasification slag increases 28-day strength to 34.86 MPa and 31.00 MPa with 5 % Ca(OH)2 and 15 % steel slag, respectively, representing gains of 51.4 % and 34.7 %. Conversely, NaOH addition results in a 28-day strength of less than 10.00 MPa, with a 60.9 % decrease at 90 days. The reasons for the heavy weakening (57 %) and enhancement (51 %) of strength are then discussed, summarising the notable differences in alkali cations, hydration mechanism and heavy metal curing mechanism. Finally, a sodium-rich C–N–S–H gel model was constructed with considering the microstructure, hydration products, and temperature. It is expected that this paper can provide a reference for the prospective study of alkaline activation.
{"title":"The influence of alkaline activation on coal gasification slag–MSWI FA based binder and its associated hydration mechanism","authors":"Yuhang Liu , Siqi Zhang , Wen Ni , Dongshang Guan , Xiang Chen , Tong Zhao , Zeping Wu , Yongchao Zheng","doi":"10.1016/j.conbuildmat.2024.139112","DOIUrl":"10.1016/j.conbuildmat.2024.139112","url":null,"abstract":"<div><div>Solid waste binders have been accepted for their eco-friendliness and good mechanical properties. The effect of alkaline activators on binder hydration process is currently a hot research topic in this field. However, there is a lack of systematic summary and analysis on how to utilize the synergistic cooperation among various ions to promote the hydration reaction. This paper designs a scientific system using the chemical composition from gypsum, municipal solid waste incineration fly ash and steel slag, highlighting the differences of alkaline activations on low-hydration coal gasification slag. Results show that replacing 40 % of blast furnace slag with coal gasification slag increases 28-day strength to 34.86 MPa and 31.00 MPa with 5 % Ca(OH)<sub>2</sub> and 15 % steel slag, respectively, representing gains of 51.4 % and 34.7 %. Conversely, NaOH addition results in a 28-day strength of less than 10.00 MPa, with a 60.9 % decrease at 90 days. The reasons for the heavy weakening (57 %) and enhancement (51 %) of strength are then discussed, summarising the notable differences in alkali cations, hydration mechanism and heavy metal curing mechanism. Finally, a sodium-rich C–N–S–H gel model was constructed with considering the microstructure, hydration products, and temperature. It is expected that this paper can provide a reference for the prospective study of alkaline activation.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"453 ","pages":"Article 139112"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659483","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}
Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139080
Rohit Rodhia , Surya Kant Sahdeo , Brind Kumar
The soaring quantity of solid garbage resulting from fast population expansion requires immediate sustainable waste management strategies. A viable strategy is to reutilise solid waste products as alternative resources in construction, thereby preserving limited raw materials. The study evaluates the prospects of substituting ceramic waste tile powder (CWTP) partially for cement in foam concrete (FC) to improve environmental sustainability while satisfying essential concrete performance criteria. The study investigates the composition, morphology, and pozzolanic activity of CWTP, together with its impact on the mechanical, microstructural, and durability characteristics of FC. CWTP replaced cement at 10 %, 30 %, 50 %, 70 %, and 90 %, and its effects on compressive, flexural, tensile strengths, porosity, and water absorption were evaluated over time. This study tackles several of significant challenges, including how to integrate waste materials—which frequently degrade performance—while maintaining strength and durability of Foam Concrete. Significant findings indicate that substituting up to 50 % of cement with CWTP yields mechanical qualities that conform to ACI 523 R 2014 criteria, while simultaneously enhancing durability, including improved resistance to sulphates, chlorides, and abrasion. Microstructural study by SEM and XRD validated the advantageous pozzolanic response of CWTP, especially during the later phases of curing. This study presents a new durability index (DI) for evaluating FC mixtures in harsh environments, determining that 50 % CWTP substitution maximises both strength and durability. The results highlight the promise of CWTP as a sustainable substitute for cement, providing environmental advantages and technological viability in foam concrete applications.
{"title":"Mechanical, microstructural and durable characteristics of foam concrete ceramic mixes exposed to H2SO4 and HCl solution","authors":"Rohit Rodhia , Surya Kant Sahdeo , Brind Kumar","doi":"10.1016/j.conbuildmat.2024.139080","DOIUrl":"10.1016/j.conbuildmat.2024.139080","url":null,"abstract":"<div><div>The soaring quantity of solid garbage resulting from fast population expansion requires immediate sustainable waste management strategies. A viable strategy is to reutilise solid waste products as alternative resources in construction, thereby preserving limited raw materials. The study evaluates the prospects of substituting ceramic waste tile powder (CWTP) partially for cement in foam concrete (FC) to improve environmental sustainability while satisfying essential concrete performance criteria. The study investigates the composition, morphology, and pozzolanic activity of CWTP, together with its impact on the mechanical, microstructural, and durability characteristics of FC. CWTP replaced cement at 10 %, 30 %, 50 %, 70 %, and 90 %, and its effects on compressive, flexural, tensile strengths, porosity, and water absorption were evaluated over time. This study tackles several of significant challenges, including how to integrate waste materials—which frequently degrade performance—while maintaining strength and durability of Foam Concrete. Significant findings indicate that substituting up to 50 % of cement with CWTP yields mechanical qualities that conform to ACI 523 R 2014 criteria, while simultaneously enhancing durability, including improved resistance to sulphates, chlorides, and abrasion. Microstructural study by SEM and XRD validated the advantageous pozzolanic response of CWTP, especially during the later phases of curing. This study presents a new durability index (DI) for evaluating FC mixtures in harsh environments, determining that 50 % CWTP substitution maximises both strength and durability. The results highlight the promise of CWTP as a sustainable substitute for cement, providing environmental advantages and technological viability in foam concrete applications.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"454 ","pages":"Article 139080"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651287","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}
Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139146
Haoliang Dong , Huajian Li , Zhiqiang Yang , Henan Shi , Liangshun Li , Fali Huang , Zhen Wang , Zhonglai Yi
In certain extreme environments, the bearing capacity of concrete structures diminishes significantly as temperatures soar, simultaneously exposing them to a heightened risk of brittle cracking. The paper aims to elucidate the fracture toughness of waterborne polyurethane modified concrete (WPMC) at different temperatures. Furthermore, a predictive model for the fracture toughness of WPMC, which incorporates both temperature and the waterborne polyurethane (WP) content, is proposed. The flexural strength and fracture toughness of WPMC were tested separately at 20℃, 40℃, 60℃, and 80℃. Utilizing digital image correlation (DIC) technology, the bottom longitudinal strain of WPMC under flexural loading was analyzed. The impact of temperature and WP content on the energy absorption capacity and deformation behavior of WPMC exposed to extreme environment was also investigated. By introducing the microstructural parameters C and Cw to characterize the elastic and plastic deformations of WPMC before and after cracking, a prediction model between the microstructural parameters and temperature, WP content was established. This model enables the prediction of the fracture toughness KIC of WPMC at different temperatures by measuring Fmax.
{"title":"Prediction model for fracture toughness of waterborne polyurethane modified concrete at different temperatures","authors":"Haoliang Dong , Huajian Li , Zhiqiang Yang , Henan Shi , Liangshun Li , Fali Huang , Zhen Wang , Zhonglai Yi","doi":"10.1016/j.conbuildmat.2024.139146","DOIUrl":"10.1016/j.conbuildmat.2024.139146","url":null,"abstract":"<div><div>In certain extreme environments, the bearing capacity of concrete structures diminishes significantly as temperatures soar, simultaneously exposing them to a heightened risk of brittle cracking. The paper aims to elucidate the fracture toughness of waterborne polyurethane modified concrete (WPMC) at different temperatures. Furthermore, a predictive model for the fracture toughness of WPMC, which incorporates both temperature and the waterborne polyurethane (WP) content, is proposed. The flexural strength and fracture toughness of WPMC were tested separately at 20℃, 40℃, 60℃, and 80℃. Utilizing digital image correlation (DIC) technology, the bottom longitudinal strain of WPMC under flexural loading was analyzed. The impact of temperature and WP content on the energy absorption capacity and deformation behavior of WPMC exposed to extreme environment was also investigated. By introducing the microstructural parameters <em>C</em> and <em>C</em><sub>w</sub> to characterize the elastic and plastic deformations of WPMC before and after cracking, a prediction model between the microstructural parameters and temperature, WP content was established. This model enables the prediction of the fracture toughness <em>K</em><sub>IC</sub> of WPMC at different temperatures by measuring <em>F</em><sub>max</sub>.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"453 ","pages":"Article 139146"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659308","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}
Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139079
Zhongshao Yao , Mingli Li , Shibo Huang , Ming Chang , Zhibin Yang
The grouting reinforcement technology is an essential method to enhance the mechanical performance of fractured rock masses and the effectiveness of reinforcement varies with different grouting materials. To further understand the mechanical improvement capabilities of each grout and the reinforcement mechanisms at the grout-rock interface, this study prepared samples with different grouting materials (sulphoaluminate cement (SAC), ultra-fine cement (UFC), and epoxy resin (EPR)) and the uniaxial compression tests were conducted. Based on these tests, the macro and micro mechanical characteristics of different grouting samples were revealed using particle image velocimetry (PIV), acoustic emission (AE), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR). The results indicate that grouting helps improve the mechanical performance and deformation resistance of fractured rock masses. It effectively limited lateral displacement of the samples, reduced stress concentration at fracture tips, enhanced shear effects during sample fracture, and altered the crack propagation process and failure modes. Compared to the fractured samples, the peak strength of SAC, UFC, and EPR samples increased by 17.8 %, 23.4 %, and 28.3 %, and the elastic modulus increased by 14.3 %, 7.9 %, and 24.8 %, respectively. Among these, the EPR samples exhibited a similarity in parameter indicators to intact samples of over 85 %, making EPR the optimal grouting material. The degree of grout-rock fusion is the primary factor influencing grouting reinforcement effectiveness. SAC is covering-type cement, UFC is embedded cement, EPR is a fusion material, and the fusion-type materials are more beneficial for improving the mechanical performance of fractured rocks.
{"title":"Study on the impact of grouting reinforcement on the mechanical behavior of non-penetrating fracture sandstone","authors":"Zhongshao Yao , Mingli Li , Shibo Huang , Ming Chang , Zhibin Yang","doi":"10.1016/j.conbuildmat.2024.139079","DOIUrl":"10.1016/j.conbuildmat.2024.139079","url":null,"abstract":"<div><div>The grouting reinforcement technology is an essential method to enhance the mechanical performance of fractured rock masses and the effectiveness of reinforcement varies with different grouting materials. To further understand the mechanical improvement capabilities of each grout and the reinforcement mechanisms at the grout-rock interface, this study prepared samples with different grouting materials (sulphoaluminate cement (SAC), ultra-fine cement (UFC), and epoxy resin (EPR)) and the uniaxial compression tests were conducted. Based on these tests, the macro and micro mechanical characteristics of different grouting samples were revealed using particle image velocimetry (PIV), acoustic emission (AE), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR). The results indicate that grouting helps improve the mechanical performance and deformation resistance of fractured rock masses. It effectively limited lateral displacement of the samples, reduced stress concentration at fracture tips, enhanced shear effects during sample fracture, and altered the crack propagation process and failure modes. Compared to the fractured samples, the peak strength of SAC, UFC, and EPR samples increased by 17.8 %, 23.4 %, and 28.3 %, and the elastic modulus increased by 14.3 %, 7.9 %, and 24.8 %, respectively. Among these, the EPR samples exhibited a similarity in parameter indicators to intact samples of over 85 %, making EPR the optimal grouting material. The degree of grout-rock fusion is the primary factor influencing grouting reinforcement effectiveness. SAC is covering-type cement, UFC is embedded cement, EPR is a fusion material, and the fusion-type materials are more beneficial for improving the mechanical performance of fractured rocks.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"453 ","pages":"Article 139079"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658888","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}
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