In prestressed concrete continuous beams, building code provisions often allow for a reduction in the moment at a critical section (calculated through elastic analysis). This reduction is permitted as long as the moments in all other sections are adjusted to maintain equilibrium and support the designated loads. However, the allowable moment redistribution percentage (MRP) for prestressed concrete beams (PCBs) remains a topic of debate. Many codes currently assign a similar MRP limitation to both PCBs and reinforced concrete members. This approach might be over-simplistic for PCBs due to their unique behaviour. This paper proposes a method for identifying the maximum available MRP. An in-depth study was conducted on the maximum available MRP of PCBs based on calibrated finite element models. The results show that the parameters such as passive reinforcement ratio, steel yield strength, slenderness ratio, eccentricity of prestressing tendons, concrete grade, and load pattern, which were not considered in the codes, influence the maximum available MRP to an extent. Using the same permissible MRP as reinforced concrete beams may be inappropriate. Finally, an equation is proposed to estimate the maximum available MRP for PCBs.
{"title":"Moment redistribution capacity in prestressed concrete continuous beams","authors":"Da Luo, Bing Li","doi":"10.1680/jmacr.24.00138","DOIUrl":"https://doi.org/10.1680/jmacr.24.00138","url":null,"abstract":"In prestressed concrete continuous beams, building code provisions often allow for a reduction in the moment at a critical section (calculated through elastic analysis). This reduction is permitted as long as the moments in all other sections are adjusted to maintain equilibrium and support the designated loads. However, the allowable moment redistribution percentage (MRP) for prestressed concrete beams (PCBs) remains a topic of debate. Many codes currently assign a similar MRP limitation to both PCBs and reinforced concrete members. This approach might be over-simplistic for PCBs due to their unique behaviour. This paper proposes a method for identifying the maximum available MRP. An in-depth study was conducted on the maximum available MRP of PCBs based on calibrated finite element models. The results show that the parameters such as passive reinforcement ratio, steel yield strength, slenderness ratio, eccentricity of prestressing tendons, concrete grade, and load pattern, which were not considered in the codes, influence the maximum available MRP to an extent. Using the same permissible MRP as reinforced concrete beams may be inappropriate. Finally, an equation is proposed to estimate the maximum available MRP for PCBs.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141919411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The use of microcapsules as a preservative agent for healing materials has led to a great revolution in the repair of materials. Microcapsules have been used in medicine, agriculture, metallurgy, and mechanics. In civil engineering applications, microcapsules are usually used for the self-healing of concrete, asphalt and cementitious materials. Concrete and cement are widely used in civil engineering and they are distinguished as the predominant construction materials worldwide. The objective of this study is to design and produce urea-formaldehyde microcapsules for the recovery of reactive powder concrete (RPC). The obtained results demonstrated that the RPC specimens containing microcapsules exhibit different behaviors, compared to RPC specimens without microcapsules. For all RPC specimens containing microcapsule, measured values of strengths were lower than specimens without microcapsules. The minimum reduction in the compressive strength was observed in specimens with microcapsules content ranging from 4% to 6% by cement weight. The healing ratio of the compressive strength increased by increasing the weight percentage of microcapsules. Scanning electron microscope (SEM) imaging and energy dispersive spectroscopy (EDS) analysis were used to observe the process of crack healing. The SEM/EDS results showed that cracks are filled by healing products.
{"title":"Evaluation of self-healing in reactive powder concrete with urea-formaldehyde/epoxy microcapsules","authors":"H. Khosravi, Effat Mehrazin, M. Lezgy-Nazargah","doi":"10.1680/jmacr.23.00302","DOIUrl":"https://doi.org/10.1680/jmacr.23.00302","url":null,"abstract":"The use of microcapsules as a preservative agent for healing materials has led to a great revolution in the repair of materials. Microcapsules have been used in medicine, agriculture, metallurgy, and mechanics. In civil engineering applications, microcapsules are usually used for the self-healing of concrete, asphalt and cementitious materials. Concrete and cement are widely used in civil engineering and they are distinguished as the predominant construction materials worldwide. The objective of this study is to design and produce urea-formaldehyde microcapsules for the recovery of reactive powder concrete (RPC). The obtained results demonstrated that the RPC specimens containing microcapsules exhibit different behaviors, compared to RPC specimens without microcapsules. For all RPC specimens containing microcapsule, measured values of strengths were lower than specimens without microcapsules. The minimum reduction in the compressive strength was observed in specimens with microcapsules content ranging from 4% to 6% by cement weight. The healing ratio of the compressive strength increased by increasing the weight percentage of microcapsules. Scanning electron microscope (SEM) imaging and energy dispersive spectroscopy (EDS) analysis were used to observe the process of crack healing. The SEM/EDS results showed that cracks are filled by healing products.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141920604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In prestressed concrete continuous beams, building code provisions often allow for a reduction in the moment at a critical section (calculated through elastic analysis). This reduction is permitted as long as the moments in all other sections are adjusted to maintain equilibrium and support the designated loads. However, the allowable moment redistribution percentage (MRP) for prestressed concrete beams (PCBs) remains a topic of debate. Many codes currently assign a similar MRP limitation to both PCBs and reinforced concrete members. This approach might be over-simplistic for PCBs due to their unique behaviour. This paper proposes a method for identifying the maximum available MRP. An in-depth study was conducted on the maximum available MRP of PCBs based on calibrated finite element models. The results show that the parameters such as passive reinforcement ratio, steel yield strength, slenderness ratio, eccentricity of prestressing tendons, concrete grade, and load pattern, which were not considered in the codes, influence the maximum available MRP to an extent. Using the same permissible MRP as reinforced concrete beams may be inappropriate. Finally, an equation is proposed to estimate the maximum available MRP for PCBs.
{"title":"Moment redistribution capacity in prestressed concrete continuous beams","authors":"Da Luo, Bing Li","doi":"10.1680/jmacr.24.00138","DOIUrl":"https://doi.org/10.1680/jmacr.24.00138","url":null,"abstract":"In prestressed concrete continuous beams, building code provisions often allow for a reduction in the moment at a critical section (calculated through elastic analysis). This reduction is permitted as long as the moments in all other sections are adjusted to maintain equilibrium and support the designated loads. However, the allowable moment redistribution percentage (MRP) for prestressed concrete beams (PCBs) remains a topic of debate. Many codes currently assign a similar MRP limitation to both PCBs and reinforced concrete members. This approach might be over-simplistic for PCBs due to their unique behaviour. This paper proposes a method for identifying the maximum available MRP. An in-depth study was conducted on the maximum available MRP of PCBs based on calibrated finite element models. The results show that the parameters such as passive reinforcement ratio, steel yield strength, slenderness ratio, eccentricity of prestressing tendons, concrete grade, and load pattern, which were not considered in the codes, influence the maximum available MRP to an extent. Using the same permissible MRP as reinforced concrete beams may be inappropriate. Finally, an equation is proposed to estimate the maximum available MRP for PCBs.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141919896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nagesh Pratap Singh, G. Santha Kumar, S. Ganesh Kumar
In many circumstances, water passing through pervious concrete (PC) is contaminated with soil sediments. Hence, in such cases, the clogging of PC affects its functional characteristics and service life conditions. The clogging behaviour of different void based PC under the influence of soil-contaminated water is not yet clearly understood. This study explores the effect of using three different kinds of soil-contaminated water such as sand contaminated water, clayey silt contaminated water, and a mixture of sand and clayey silt contaminated water on the pore clogging phenomenon of different void based PC. Three different concentrations of soil contaminated water for each kind of PC were employed for carrying out clogging process in this present study. The clogging process was executed until reaching the minimum permeability level of the PC. This paper also elucidates the effectiveness of the washing process on the de-clogging behaviour of each clogged PC. In addition to this, various characteristics of different void-based PC, such as, strength, permeability, macroscopic pores distribution, and leaching parameters, were assessed. The outcomes of the experimental research work disseminate consensus behaviour of PC that would be helpful to provide a conceivable solution to develop the desirable performance of PC for wide applications.
在许多情况下，通过透水混凝土（PC）的水都会受到土壤沉积物的污染。因此，在这种情况下，透水混凝土的堵塞会影响其功能特性和使用寿命。目前还不清楚不同空隙基 PC 在土壤污染水影响下的堵塞行为。本研究探讨了使用三种不同的土壤污染水（如砂污染水、粘质粉土污染水以及砂和粘质粉土混合污染水）对不同空隙基 PC 的孔隙堵塞现象的影响。在本研究中，每种 PC 都采用了三种不同浓度的土壤污染水进行堵塞处理。堵塞过程一直持续到 PC 的最小渗透性水平为止。本文还阐明了清洗过程对每种堵塞 PC 的去堵塞性能的影响。此外，还评估了不同空基 PC 的各种特性，如强度、渗透性、宏观孔隙分布和浸出参数。实验研究工作的成果就 PC 的行为达成了共识，这将有助于为 PC 的广泛应用提供一个可行的解决方案，以开发 PC 的理想性能。
{"title":"Influence of soil contaminated water on clogging phenomenon of different void based pervious concrete","authors":"Nagesh Pratap Singh, G. Santha Kumar, S. Ganesh Kumar","doi":"10.1680/jmacr.24.00009","DOIUrl":"https://doi.org/10.1680/jmacr.24.00009","url":null,"abstract":"In many circumstances, water passing through pervious concrete (PC) is contaminated with soil sediments. Hence, in such cases, the clogging of PC affects its functional characteristics and service life conditions. The clogging behaviour of different void based PC under the influence of soil-contaminated water is not yet clearly understood. This study explores the effect of using three different kinds of soil-contaminated water such as sand contaminated water, clayey silt contaminated water, and a mixture of sand and clayey silt contaminated water on the pore clogging phenomenon of different void based PC. Three different concentrations of soil contaminated water for each kind of PC were employed for carrying out clogging process in this present study. The clogging process was executed until reaching the minimum permeability level of the PC. This paper also elucidates the effectiveness of the washing process on the de-clogging behaviour of each clogged PC. In addition to this, various characteristics of different void-based PC, such as, strength, permeability, macroscopic pores distribution, and leaching parameters, were assessed. The outcomes of the experimental research work disseminate consensus behaviour of PC that would be helpful to provide a conceivable solution to develop the desirable performance of PC for wide applications.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141809075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work successfully prepared fair-faced concrete with mirror effect. The gray value standard deviation, porosity, crack rate and glossiness of the concrete surface were used to characterize the apparent quality of fair-faced concrete. The effect of polycarboxylate superplasticizer and polyacrylamide viscosity-modifying admixture on mirror effect of fair-faced concrete was investigated. The changes of hydration products and microstructure of fair-faced concrete were monitored by the measurements of X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM) and mercury intrusion porosity (MIP), and the potential mechanism was analyzed. The results indicate that the polyacrylamide reduces the number and size of Ca(OH)2 and change the morphology of Ca(OH)2 crystals from large-size parallel stacking state to small-size edge corrosion structure. The polyacrylamide can refine the pore size of concrete, the most probable pore size at the optimum dosage is 13.73 nm, which is much lower than that at other dosages. The usage of the polycarboxylate superplasticizer will introduce air, which has adverse effect on the concrete surface. But polycarboxylate superplasticizer can also improve the flowability of concrete and make bubbles easy to discharge. The combined action of polycarboxylate superplasticizer and polyacrylamide contributes the fair-faced concrete for better mirror effect.
{"title":"Influence of polycarboxylate superplasticizer and polyacrylamide on mirror effect of fair-faced concrete","authors":"Hongxiang Zheng, Weizhun Jin, Liang Wang, Binbin Na, Zhengxiang Lin, Jinghui Zhang, Qinghua Huang, Linhua Jiang","doi":"10.1680/jmacr.24.00122","DOIUrl":"https://doi.org/10.1680/jmacr.24.00122","url":null,"abstract":"This work successfully prepared fair-faced concrete with mirror effect. The gray value standard deviation, porosity, crack rate and glossiness of the concrete surface were used to characterize the apparent quality of fair-faced concrete. The effect of polycarboxylate superplasticizer and polyacrylamide viscosity-modifying admixture on mirror effect of fair-faced concrete was investigated. The changes of hydration products and microstructure of fair-faced concrete were monitored by the measurements of X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM) and mercury intrusion porosity (MIP), and the potential mechanism was analyzed. The results indicate that the polyacrylamide reduces the number and size of Ca(OH)2 and change the morphology of Ca(OH)2 crystals from large-size parallel stacking state to small-size edge corrosion structure. The polyacrylamide can refine the pore size of concrete, the most probable pore size at the optimum dosage is 13.73 nm, which is much lower than that at other dosages. The usage of the polycarboxylate superplasticizer will introduce air, which has adverse effect on the concrete surface. But polycarboxylate superplasticizer can also improve the flowability of concrete and make bubbles easy to discharge. The combined action of polycarboxylate superplasticizer and polyacrylamide contributes the fair-faced concrete for better mirror effect.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141816520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Saswat Dwibedy, Suraj Kumar Parhi, Soumyaranjan Panda, S. K. Panigrahi
Geopolymer is an inorganic polymer whose formation is based on the reaction between the precursors and some reagents which may be alkaline or acidic. The geopolymerization process involves the reaction between alumina-silicate (Al-Si) materials known as precursors and reagents producing a three-dimensional polymeric network. In this manuscript, a detailed classification along with various oxide contents present in the precursors globally used for geopolymer concrete (GPC) production is extracted. As precursors used in the process of geopolymerization involve a wide range of variations in their physio-chemical features, it becomes difficult to control the GPC properties without going into a micro-level understanding of the precursor characteristics affecting the geopolymerization mechanism. A comprehensive study is conducted on the influence of these physiochemical precursor characteristics on the geopolymerization process and GPC property development. Finally, a critical observation is drawn to design a suitable precursor, along with possible methods employed to achieve desired GPC property development.
{"title":"Performance of precursor characteristics in the realization of geopolymer concrete: a review","authors":"Saswat Dwibedy, Suraj Kumar Parhi, Soumyaranjan Panda, S. K. Panigrahi","doi":"10.1680/jmacr.24.00120","DOIUrl":"https://doi.org/10.1680/jmacr.24.00120","url":null,"abstract":"Geopolymer is an inorganic polymer whose formation is based on the reaction between the precursors and some reagents which may be alkaline or acidic. The geopolymerization process involves the reaction between alumina-silicate (Al-Si) materials known as precursors and reagents producing a three-dimensional polymeric network. In this manuscript, a detailed classification along with various oxide contents present in the precursors globally used for geopolymer concrete (GPC) production is extracted. As precursors used in the process of geopolymerization involve a wide range of variations in their physio-chemical features, it becomes difficult to control the GPC properties without going into a micro-level understanding of the precursor characteristics affecting the geopolymerization mechanism. A comprehensive study is conducted on the influence of these physiochemical precursor characteristics on the geopolymerization process and GPC property development. Finally, a critical observation is drawn to design a suitable precursor, along with possible methods employed to achieve desired GPC property development.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141826542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ajeesh Koorikkattil, S. K. Nayar, Veena Venudharan
The present research is intended to address the adequacy of flexural toughness-based material models such as equivalent and residual flexural strength, and the deflection limits at which these parameters are estimated for design of fibre reinforced concrete (FRC), for various applications such as slabs-on-grade/pavements. The work is an experimental study using FRC concrete mixes with individual and hybrid combinations of hooked-end steel (SF) and macro polypropylene fibres (PF). The experimental investigation consisted of toughness testing unnotched and notched prisms and square slabs, prepared with a typical grade of concrete used for FRC pavement applications. To validate the material models, a comparison was made between the theoretical moment/load calculated based on material flexural toughness parameters and the actual moment obtained from slabs using actual yield line formed during testing. From the study it is observed that overall, both equivalent (from unnotched prism test) and residual (from notched prism test) flexural strength, are suitable for designing FRC slabs, however the equivalent strength parameter shows better correlation to the slab response. The results also indicate that the hybrid mixes of PF and SF, with a higher volume fraction of 0.6% Vf, shows a marginal increase in flexural performance, in comparison to the mixes with lower volume fraction but no or minimal synergy due to hybridisation.
{"title":"Yield line-based design of fibre reinforced concrete: assessment of suitability of material models","authors":"Ajeesh Koorikkattil, S. K. Nayar, Veena Venudharan","doi":"10.1680/jmacr.24.00096","DOIUrl":"https://doi.org/10.1680/jmacr.24.00096","url":null,"abstract":"The present research is intended to address the adequacy of flexural toughness-based material models such as equivalent and residual flexural strength, and the deflection limits at which these parameters are estimated for design of fibre reinforced concrete (FRC), for various applications such as slabs-on-grade/pavements. The work is an experimental study using FRC concrete mixes with individual and hybrid combinations of hooked-end steel (SF) and macro polypropylene fibres (PF). The experimental investigation consisted of toughness testing unnotched and notched prisms and square slabs, prepared with a typical grade of concrete used for FRC pavement applications. To validate the material models, a comparison was made between the theoretical moment/load calculated based on material flexural toughness parameters and the actual moment obtained from slabs using actual yield line formed during testing. From the study it is observed that overall, both equivalent (from unnotched prism test) and residual (from notched prism test) flexural strength, are suitable for designing FRC slabs, however the equivalent strength parameter shows better correlation to the slab response. The results also indicate that the hybrid mixes of PF and SF, with a higher volume fraction of 0.6% Vf, shows a marginal increase in flexural performance, in comparison to the mixes with lower volume fraction but no or minimal synergy due to hybridisation.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141830077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper reports the durability properties of slag-glass powder (GP) geopolymer mortars at different GP contents and compares them with Portland cement mortars (PCM). The slag-GP mixes are activated with 6 M NaOH solution at 0.35 liquid-to-solid ratio. The performance of 28-day cured specimens under high-temperature exposures, wetting-drying and freezing-thawing cycles, water slaking, surface abrasion, and alkali-silica reactions (ASR) are examined. Scanning electron microscopic analysis is carried out to identify the microstructural changes in the material. The study outcomes indicate that an appropriate GP content (10%) enhances the performance of slag-GP binary geopolymers and improves its durability. However, ASR expansion is found to be increased marginally. The geopolymer specimens achieved higher strength and durability than PCM due to a dense and compact microstructure with significant gel formations.
本文报告了不同玻璃粉含量的矿渣-玻璃粉（GP）土工聚合物砂浆的耐久性能，并将其与波特兰水泥砂浆（PCM）进行了比较。矿渣-玻璃粉混合物用 6 M NaOH 溶液活化，液固比为 0.35。研究了在高温暴露、湿润-干燥和冻融循环、水荡、表面磨损和碱-硅反应（ASR）条件下 28 天固化试样的性能。通过扫描电子显微镜分析来确定材料的微观结构变化。研究结果表明，适当的 GP 含量（10%）可提高矿渣-GP 二元土工聚合物的性能，并改善其耐久性。不过，ASR 膨胀率略有增加。与 PCM 相比，土工聚合物试样具有更高的强度和耐久性，这得益于其致密紧凑的微观结构和显著的凝胶形成。
{"title":"Durability properties of slag-waste glass binary geopolymer","authors":"Datla Neeraj Varma, Suresh Prasad Singh","doi":"10.1680/jmacr.24.00086","DOIUrl":"https://doi.org/10.1680/jmacr.24.00086","url":null,"abstract":"This paper reports the durability properties of slag-glass powder (GP) geopolymer mortars at different GP contents and compares them with Portland cement mortars (PCM). The slag-GP mixes are activated with 6 M NaOH solution at 0.35 liquid-to-solid ratio. The performance of 28-day cured specimens under high-temperature exposures, wetting-drying and freezing-thawing cycles, water slaking, surface abrasion, and alkali-silica reactions (ASR) are examined. Scanning electron microscopic analysis is carried out to identify the microstructural changes in the material. The study outcomes indicate that an appropriate GP content (10%) enhances the performance of slag-GP binary geopolymers and improves its durability. However, ASR expansion is found to be increased marginally. The geopolymer specimens achieved higher strength and durability than PCM due to a dense and compact microstructure with significant gel formations.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141832178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, approaches to synthesizing rapid tannery sludge/metakaolin geopolymer repair materials were explored to investigate tannery sludge treatment and utilization. The setting time and 1-d compressive strength were taken as indicators for evaluating the performance of the geopolymer as a repair material. The effects of the Si/Al ratio, Na/Si ratio, water/cement ratio, and tannery sludge content were determined, and the durability of the geopolymer was also studied. The optimum formula met the requirements of a pavement repair material when the Si/Al ratio, Na/Si ratio, water/cement ratio, and tannery sludge content were 2.58, 0.33, 0.67, and 10%, respectively. The final setting times of this formula were 102 min. The 1-d compressive strength was 21.0 MPa, and the chromium leaching concentration was 7.52 mg·L−1. Additionally, the geopolymer exhibited good resistance to high temperatures and acid rain, and freeze-thaw processes. Therefore, a geopolymer repair material that exhibited high strength in the early stage and stable performance in the later stages was synthesized. XRD, FT-IR, MIP, and SEM were also conducted for micro-analysis, and it was found that the decrease in geopolymer gelation, and increases in the pore size and porosity resulted in a decrease in the properties of the repair materials.
{"title":"Early strength and durability of tannery sludge metakaolin based geopolymer concrete pavement repair material","authors":"Mantong Jin, Ganghong Yang, Zhuohui Wang, Peisen Zhao, Xinrun Zheng, Zhiyan Pan, Jiangfan Wu","doi":"10.1680/jmacr.23.00289","DOIUrl":"https://doi.org/10.1680/jmacr.23.00289","url":null,"abstract":"In this study, approaches to synthesizing rapid tannery sludge/metakaolin geopolymer repair materials were explored to investigate tannery sludge treatment and utilization. The setting time and 1-d compressive strength were taken as indicators for evaluating the performance of the geopolymer as a repair material. The effects of the Si/Al ratio, Na/Si ratio, water/cement ratio, and tannery sludge content were determined, and the durability of the geopolymer was also studied. The optimum formula met the requirements of a pavement repair material when the Si/Al ratio, Na/Si ratio, water/cement ratio, and tannery sludge content were 2.58, 0.33, 0.67, and 10%, respectively. The final setting times of this formula were 102 min. The 1-d compressive strength was 21.0 MPa, and the chromium leaching concentration was 7.52 mg·L−1. Additionally, the geopolymer exhibited good resistance to high temperatures and acid rain, and freeze-thaw processes. Therefore, a geopolymer repair material that exhibited high strength in the early stage and stable performance in the later stages was synthesized. XRD, FT-IR, MIP, and SEM were also conducted for micro-analysis, and it was found that the decrease in geopolymer gelation, and increases in the pore size and porosity resulted in a decrease in the properties of the repair materials.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141654309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wet storage effects on fly ash, mean processing may be necessary to achieve physical properties required for use in concrete. This paper considers drying, de-agglomeration and milling of various wet stored fly ashes at laboratory and pilot/benchtop scales, towards meeting these. In the laboratory, different batch quantities and milling times with as received/pre-screened materials were examined using a ball mill. Greater particle size reductions were obtained with increased milling time but at gradually reducing rates. Pre-screening and batch quantity had relatively minor effects on particle size reductions, with little difference found between these materials and dry stored fly ash. Extended milling time resulted in: a darkening of colour; slight increases in loss-on-ignition, the main oxides content, and crystalline components; reductions in water requirement (to a point); and greater reactivity. Similar effects were generally noted in concrete for the superplasticizing admixture dose to achieve a target slump and compressive (cube) strength. At pilot/benchtop scale, a dryer-pulverizer and jet mill were used, which gave general agreement with the behaviour noted in the laboratory, but with the effects tending to be less. Fineness levels in Standards were achievable, with subsequent performance appearing to depend on the milling process used.
{"title":"Mechanical processing of wet stored fly ash for use as a cement component in concrete","authors":"M. J. McCarthy, T. Hope, L. Csetenyi","doi":"10.1680/jmacr.23.00303","DOIUrl":"https://doi.org/10.1680/jmacr.23.00303","url":null,"abstract":"Wet storage effects on fly ash, mean processing may be necessary to achieve physical properties required for use in concrete. This paper considers drying, de-agglomeration and milling of various wet stored fly ashes at laboratory and pilot/benchtop scales, towards meeting these. In the laboratory, different batch quantities and milling times with as received/pre-screened materials were examined using a ball mill. Greater particle size reductions were obtained with increased milling time but at gradually reducing rates. Pre-screening and batch quantity had relatively minor effects on particle size reductions, with little difference found between these materials and dry stored fly ash. Extended milling time resulted in: a darkening of colour; slight increases in loss-on-ignition, the main oxides content, and crystalline components; reductions in water requirement (to a point); and greater reactivity. Similar effects were generally noted in concrete for the superplasticizing admixture dose to achieve a target slump and compressive (cube) strength. At pilot/benchtop scale, a dryer-pulverizer and jet mill were used, which gave general agreement with the behaviour noted in the laboratory, but with the effects tending to be less. Fineness levels in Standards were achievable, with subsequent performance appearing to depend on the milling process used.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141835885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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