This research investigated the water permeability coefficient of fly ash-based geopolymer concrete. The effect of sodium hydroxide （Na（OH）） concentrations and Si/AI ratios on water permeability and compressive str...This research investigated the water permeability coefficient of fly ash-based geopolymer concrete. The effect of sodium hydroxide （Na（OH）） concentrations and Si/AI ratios on water permeability and compressive strength of geopolymer concretes were studied. The geopolymer concrete were prepared from Mae Moh fly ash with sodium silicate （Na2SiO3） and sodium hydroxide （Na（OH）） solutions. In the first group, concentration of Na（OH） was varied at 8, 10, 12, and 14 molar and the Si/AI ratio was kept constant at 1.98. In the second group, a concentration of Na（OH） was kept constant at 14 molar and the Si/AI ratio was varied at 2.2, 2.4, 2.6, and 2.8. The hardened concretes were air-cured in laboratory. The compressive strength and water permeability were tested at the age of 28 and 60 days. The results showed that compressive strengths of geopolymer concrete significantly increased with the increase of a concentration of Na（OH） and Si/AI ratio. The water permeability coefficients increase with the decrease of compressive strength. In addition, the high reduction of water permeability coefficients with time was found in geopolymer concrete with lower Na（OH） concentration than that higher Na（OH） concentration.展开更多
The geopolymer synthesized by alkali-activated fly ash was firstly used as a novel photocatalyst for degradation of methylene blue （MB） dye from wastewater. The geopolymer is composed of nanoparticulates with an ave...The geopolymer synthesized by alkali-activated fly ash was firstly used as a novel photocatalyst for degradation of methylene blue （MB） dye from wastewater. The geopolymer is composed of nanoparticulates with an average particle size of about 50 nm, More than 90% of pore volume in the fly ash-based geopolymet predominately centralized on the pore size in the range of 17-700 nm. The degradation efficiency of MB dye by fly ash-based geopolymer catalyst was up to 92.79% under UV irradiation due to the synergistic effect of adsorption and semiconductor photocatalysis. The pseudo-first-order and pseudo-second-order rate equations as well as intra-particle diffusion rate equation were employed to correlate analysis for the adsorption kinetics of MB dye, The experimental data agreed well with pseudo-second-order rate equation in both cases of with UV and without UV irradiations. The intra-particle diffusion process is not the rate determining step. The photocatalytic degradation of MB dye in solution obeys third-order reaction kinetics.展开更多
Mine filling materials urgently need to improve mechanical properties and achieve low-carbon transformation.This study explores the mechanism of the synergistic effect of optimizing aggregate fractal grading and intro...Mine filling materials urgently need to improve mechanical properties and achieve low-carbon transformation.This study explores the mechanism of the synergistic effect of optimizing aggregate fractal grading and introducing CO_(2)nanobubble technology to improve the performance of cement-fly ash-based backfill materials(CFB).The properties including fluidity,setting time,uniaxial compressive strength,elastic modulus,porosity,microstructure and CO_(2)storage performance were systematically studied through methods such as fluidity evaluation,time test,uniaxial compression test,mercury intrusion porosimetry(MIP),scanning electron microscopy-energy dispersive spectroscopy analysis(SEM-EDS),and thermogravimetric-differential thermogravimetric analysis(TG-DTG).The experimental results show that the density and strength of the material are significantly improved under the synergistic effect of fractal dimension and CO_(2)nanobubbles.When the fractal dimension reaches 2.65,the mass ratio of coarse and fine aggregates reaches the optimal balance,and the structural density is greatly improved at the same time.At this time,the uniaxial compressive strength and elastic modulus reach their peak values,with increases of up to 13.46%and 27.47%,respectively.CO_(2)nanobubbles enhance the material properties by promoting hydration reaction and carbonization.At the microscopic level,CO_(2)nanobubble water promotes the formation of C-S-H(hydrated calcium silicate),C-A-S-H(hydrated calcium aluminium silicate)gel and CaCO_(3),which is the main way to enhance the performance.Thermogravimetric studies have shown that when the fractal dimension is 2.65,the dehydration of hydration products and the decarbonization process of CaCO_(3)are most obvious,and CO_(2)nanobubble water promotes the carbonization reaction,making it surpass the natural state.The CO_(2)sequestration quality of cement-fly ash-based materials treated with CO_(2)nanobubble water at different fractal dimensions increased by 12.4wt%to 99.8wt%.The results not only provide scientific insights for the design and implementation of low-carbon filling materials,but also provide a solid theoretical basis for strengthening green mining practices and promoting sustainable resource utilization.展开更多
Fly ash(FA),a major solid waste from coal-fired industries,represents a critical pathway for the green disposal of bulk solid waste and the low-carbon construction of transportation infrastructure,holding significant ...Fly ash(FA),a major solid waste from coal-fired industries,represents a critical pathway for the green disposal of bulk solid waste and the low-carbon construction of transportation infrastructure,holding significant strategic importance.In recent years,extensive research has been conducted on the mechanisms,optimization,and applications of FA-based road engineering materials.This review focuses on FA-based road engineering material systems,synthesizing previous studies from three perspectives:cement concrete pavement materials,asphalt mixture pavement materials,and stabilized soil road materials.The findings reveal that FA significantly enhances road material performance through its pozzolanic activity,micro-nano filling effects,and interfacial strengthening.In cement concrete systems,the synergistic interaction of pozzolanic reactions and microsphere filling achieves microstructural densification.Integrating particle size optimization,nano-modification,and alkali activation techniques can overcome the mechanical strength and durability limitations of traditional FA systems.For asphalt mixtures,leveraging FA’s porous adsorption characteristics and chemical bonding effects optimizes the asphalt-aggregate interface adhesion,while alkali activation further extends its application scope.In stabilized soil systems,FA enhances soil integrity by forming cementitious networks,with structural reinforcement achievable through alkali activation and composite stabilization.However,current research still faces unresolved challenges.These include elemental imbalances and performance limitations in single-FA-based road engineering materials,insufficient high-value applications of FA carbon sequestration technology in road materials,lack of systematic frameworks for environmental risk assessments of FA-based road systems,and constrained application scenarios for FA in road engineering.Future research should focus on innovating activation technologies to enhance the reactivity of FA,co-utilizing multi-source solid wastes,researching carbon sequestration technologies for FA-based road engineering materials,establishing environmental monitoring and evaluation systems,and promoting the application of FA in subgrade filling.The conclusions provide comprehensive insights for industrial solid waste recycling and low-carbon road construction,supporting sustainable,lowcarbon,and high-quality development in road engineering.展开更多
This study aims to investigate the feasibility of using decoration waste powder(DWP)as a partial replacement for fly ash(FA)in the preparation of geopolymer masonry mortar,and to examine the effect of different DWP re...This study aims to investigate the feasibility of using decoration waste powder(DWP)as a partial replacement for fly ash(FA)in the preparation of geopolymer masonry mortar,and to examine the effect of different DWP replacement rates(0%-40%)on the fresh and mechanical properties of the mortar.The results showed that each group of geopolymer masonry mortar exhibited excellent water retention performance,with a water retention rate of 100%,which was due to the unique geopolymer mortar system and high viscosity of the alkaline activator solution.Compared to the control group,the flowability of the mortar containing lower contents of DWP(10%and 20%)was higher.However,as the DWP replacement rate further increased,the flowability gradually decreased.The DWP could absorb the free water in the reaction system of geopolymer mortar,thereby limiting the occurrence of geopolymerization reaction.The incorporation of DWP in the mortar resulted in a decrease in compressive strength compared to the mortar without DWP.However,even at a replacement rate of 40%,the compressive strength of the mortar still exceeded 15 MPa,which met the requirements of the masonry mortar.It was feasible to use DWP in the geopolymer masonry mortar.Although the addition of DWP caused some performance loss,it did not affect its usability.展开更多
文摘This research investigated the water permeability coefficient of fly ash-based geopolymer concrete. The effect of sodium hydroxide （Na（OH）） concentrations and Si/AI ratios on water permeability and compressive strength of geopolymer concretes were studied. The geopolymer concrete were prepared from Mae Moh fly ash with sodium silicate （Na2SiO3） and sodium hydroxide （Na（OH）） solutions. In the first group, concentration of Na（OH） was varied at 8, 10, 12, and 14 molar and the Si/AI ratio was kept constant at 1.98. In the second group, a concentration of Na（OH） was kept constant at 14 molar and the Si/AI ratio was varied at 2.2, 2.4, 2.6, and 2.8. The hardened concretes were air-cured in laboratory. The compressive strength and water permeability were tested at the age of 28 and 60 days. The results showed that compressive strengths of geopolymer concrete significantly increased with the increase of a concentration of Na（OH） and Si/AI ratio. The water permeability coefficients increase with the decrease of compressive strength. In addition, the high reduction of water permeability coefficients with time was found in geopolymer concrete with lower Na（OH） concentration than that higher Na（OH） concentration.
基金financially supported by Industrial Key Project of Shaanxi Province(No.2010K01-080)Open Fund of State Key Laboratory of Architecture Science and Technology in West China(XAUAT)+1 种基金Xi'an University of Architecture and Technology(No.10KF05)Scientific Research Program Funded by Shaanxi Provincial Education Department(No.12JK0579)
文摘The geopolymer synthesized by alkali-activated fly ash was firstly used as a novel photocatalyst for degradation of methylene blue （MB） dye from wastewater. The geopolymer is composed of nanoparticulates with an average particle size of about 50 nm, More than 90% of pore volume in the fly ash-based geopolymet predominately centralized on the pore size in the range of 17-700 nm. The degradation efficiency of MB dye by fly ash-based geopolymer catalyst was up to 92.79% under UV irradiation due to the synergistic effect of adsorption and semiconductor photocatalysis. The pseudo-first-order and pseudo-second-order rate equations as well as intra-particle diffusion rate equation were employed to correlate analysis for the adsorption kinetics of MB dye, The experimental data agreed well with pseudo-second-order rate equation in both cases of with UV and without UV irradiations. The intra-particle diffusion process is not the rate determining step. The photocatalytic degradation of MB dye in solution obeys third-order reaction kinetics.
基金financially supported by the China Scholarship Council(CSC)。
文摘Mine filling materials urgently need to improve mechanical properties and achieve low-carbon transformation.This study explores the mechanism of the synergistic effect of optimizing aggregate fractal grading and introducing CO_(2)nanobubble technology to improve the performance of cement-fly ash-based backfill materials(CFB).The properties including fluidity,setting time,uniaxial compressive strength,elastic modulus,porosity,microstructure and CO_(2)storage performance were systematically studied through methods such as fluidity evaluation,time test,uniaxial compression test,mercury intrusion porosimetry(MIP),scanning electron microscopy-energy dispersive spectroscopy analysis(SEM-EDS),and thermogravimetric-differential thermogravimetric analysis(TG-DTG).The experimental results show that the density and strength of the material are significantly improved under the synergistic effect of fractal dimension and CO_(2)nanobubbles.When the fractal dimension reaches 2.65,the mass ratio of coarse and fine aggregates reaches the optimal balance,and the structural density is greatly improved at the same time.At this time,the uniaxial compressive strength and elastic modulus reach their peak values,with increases of up to 13.46%and 27.47%,respectively.CO_(2)nanobubbles enhance the material properties by promoting hydration reaction and carbonization.At the microscopic level,CO_(2)nanobubble water promotes the formation of C-S-H(hydrated calcium silicate),C-A-S-H(hydrated calcium aluminium silicate)gel and CaCO_(3),which is the main way to enhance the performance.Thermogravimetric studies have shown that when the fractal dimension is 2.65,the dehydration of hydration products and the decarbonization process of CaCO_(3)are most obvious,and CO_(2)nanobubble water promotes the carbonization reaction,making it surpass the natural state.The CO_(2)sequestration quality of cement-fly ash-based materials treated with CO_(2)nanobubble water at different fractal dimensions increased by 12.4wt%to 99.8wt%.The results not only provide scientific insights for the design and implementation of low-carbon filling materials,but also provide a solid theoretical basis for strengthening green mining practices and promoting sustainable resource utilization.
基金supported by the following grants:Research on Key Technologies and Large-Scale Application of Resource Utilization of Industrial Solid Waste in Expressways(No.202300196)Science and Technology Development Plan Project of the Silk Road Economic Belt Innovation-Driven Development Pilot Zone and Wuchangshi National Independent Innovation Demonstration Zone(No.2023LQ03002)Research Initiation Program for High-Level Talents Introduced on a FullTime Basis in Ningxia,China(No.2024BEH04052).
文摘Fly ash(FA),a major solid waste from coal-fired industries,represents a critical pathway for the green disposal of bulk solid waste and the low-carbon construction of transportation infrastructure,holding significant strategic importance.In recent years,extensive research has been conducted on the mechanisms,optimization,and applications of FA-based road engineering materials.This review focuses on FA-based road engineering material systems,synthesizing previous studies from three perspectives:cement concrete pavement materials,asphalt mixture pavement materials,and stabilized soil road materials.The findings reveal that FA significantly enhances road material performance through its pozzolanic activity,micro-nano filling effects,and interfacial strengthening.In cement concrete systems,the synergistic interaction of pozzolanic reactions and microsphere filling achieves microstructural densification.Integrating particle size optimization,nano-modification,and alkali activation techniques can overcome the mechanical strength and durability limitations of traditional FA systems.For asphalt mixtures,leveraging FA’s porous adsorption characteristics and chemical bonding effects optimizes the asphalt-aggregate interface adhesion,while alkali activation further extends its application scope.In stabilized soil systems,FA enhances soil integrity by forming cementitious networks,with structural reinforcement achievable through alkali activation and composite stabilization.However,current research still faces unresolved challenges.These include elemental imbalances and performance limitations in single-FA-based road engineering materials,insufficient high-value applications of FA carbon sequestration technology in road materials,lack of systematic frameworks for environmental risk assessments of FA-based road systems,and constrained application scenarios for FA in road engineering.Future research should focus on innovating activation technologies to enhance the reactivity of FA,co-utilizing multi-source solid wastes,researching carbon sequestration technologies for FA-based road engineering materials,establishing environmental monitoring and evaluation systems,and promoting the application of FA in subgrade filling.The conclusions provide comprehensive insights for industrial solid waste recycling and low-carbon road construction,supporting sustainable,lowcarbon,and high-quality development in road engineering.
基金Funded by the National Natural Science Foundation of China(No.52008046)Young Elite Scientists Sponsorship Program from JSAST(No.TJ-2023-024)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX21_2848)。
文摘This study aims to investigate the feasibility of using decoration waste powder(DWP)as a partial replacement for fly ash(FA)in the preparation of geopolymer masonry mortar,and to examine the effect of different DWP replacement rates(0%-40%)on the fresh and mechanical properties of the mortar.The results showed that each group of geopolymer masonry mortar exhibited excellent water retention performance,with a water retention rate of 100%,which was due to the unique geopolymer mortar system and high viscosity of the alkaline activator solution.Compared to the control group,the flowability of the mortar containing lower contents of DWP(10%and 20%)was higher.However,as the DWP replacement rate further increased,the flowability gradually decreased.The DWP could absorb the free water in the reaction system of geopolymer mortar,thereby limiting the occurrence of geopolymerization reaction.The incorporation of DWP in the mortar resulted in a decrease in compressive strength compared to the mortar without DWP.However,even at a replacement rate of 40%,the compressive strength of the mortar still exceeded 15 MPa,which met the requirements of the masonry mortar.It was feasible to use DWP in the geopolymer masonry mortar.Although the addition of DWP caused some performance loss,it did not affect its usability.
