The aim of this study is to enhance the value of local earth materials used in the construction of certain homes in the Republic of Guinea. Thus, a trial study to improve the quality of mud bricks using paper fibers o...The aim of this study is to enhance the value of local earth materials used in the construction of certain homes in the Republic of Guinea. Thus, a trial study to improve the quality of mud bricks using paper fibers obtained by grinding and soaking in water and then drying were used as a stabilizer in the manufacture of these mud bricks from the sample of two sites Dounkiwal (DK) (in Mamou and the sample from the urban commune of Kouroussa). To do this, certain methods and means of identification were carried out, namely: geotechnical, mineralogical and chemical analyses. Sample DK from Mamou has a silty-clay geotechnical characteristic with a plasticity index Ip of 12.75%. However, mineralogical and chemical studies showed that sample Dounkiwal (DK) (Mamou) contains a high proportion of silica and iron oxides (79.63%) and Fe2O3 (11.85%), associated with other alkaline earth oxides and ions: CaO;MgO;SO32−;Cl−, i.e. 3.96%;0.96%;0.28% and 0.039% respectively. Its loss on ignition (LOI) and insoluble residues are 15.40% and 56.36%. The evaluation of the number of huts in Upper and Middle Guinea showed that the populations of these areas have been using mud bricks for several decades in the construction of dwellings. The average value found for the compressive strength of these bricks (from samples I, II and III from Kouroussa) is 0.16 MPa. This value is appreciable in the construction of mud houses.展开更多
This study was part of the framework that contributed not only to the improvement of thermal comfort in housing but also to the decarbonization of the construction and building materials industry. For this purpose, te...This study was part of the framework that contributed not only to the improvement of thermal comfort in housing but also to the decarbonization of the construction and building materials industry. For this purpose, terracotta brick seems to meet these needs. Thus, the objective of this work was to evaluate the influence of the incorporation of coal fly ash from a thermal power plant on the physical and mechanical properties of fired bricks from grey clay in the Thicky area of Senegal. The coal fly ash was incorporated into the raw clay material in proportions of 0, 5, 10, and 15 % by weight. These two raw materials were first characterized by X-ray fluorescence spectroscopy (XRF). The XRF analyses showed that the most abundant oxides in clay were SiO2 (55.034%) and Fe2O3 (10.155%). In coal fly ash, SiO2 (38.574%) is predominant. The ash also contained Al2O3 (7.717%) and alicano-earthy melting oxides such as CaO (9.271%) and MgO (7.298%) etc. These melting oxides were necessary to facilitate the formation of the liquid phase when baking platelets. The latter, when burned at a temperature of 880°C, were characterized by determining the number of physico-mechanical parameters, such as linear shrinkage during cooking, water absorption, fire loss and compressive strength. A Hierarchical Ascending Classification of these different parameters was performed and three classes were obtained. Class 1 with better compressive strength (6.358 MPa), was in sample A (5%). Class 2 consisted of sample D (reference) and had a higher plasticity index (28.51%) and water absorption rate (11.19%). Finally, class 3, which included samples B (10%) and C (15%), had very high shrinkage and fire losses compared to other platelets. These results highlighted the possibility of using up to 5% of the coal fly ash in the production of new fired bricks with good performance.展开更多
This study investigated the therapeutic effects on metabolic syndrome(MetS)and the impact on the intestinal barrier and gut microbiota of Fu brick tea aqueous extracts(FTE)on MetS in rats fed with a high-fat diet(HFD)...This study investigated the therapeutic effects on metabolic syndrome(MetS)and the impact on the intestinal barrier and gut microbiota of Fu brick tea aqueous extracts(FTE)on MetS in rats fed with a high-fat diet(HFD).Here,the results showed that FTE supplement significantly reduced HFD-induced weight gain,adiposity,dyslipidemia,fasting blood glucose(FBG)increment,and non-alcoholic fatty liver disease(NAFLD).Moreover,FTE supplement resulted in a decline in lipopolysaccharide(LPS)level and attenuation of colonic inflammation and oxidative stress to protect the intestinal barrier function.FTE supplement also maintained the intestinal barrier integrity by improving histological appearance and promoting ZO-1,Occludin,and Claudin-1 protein expression levels.Meanwhile,FTE supplement alleviated the gut microbiota dysbiosis by enhancing the Firmicutes/Bacteroidetes(F/B)ratio and stimulating the colonization of probiotic bacteria such as Akkermansia,Lactobacillus,Adlercreutzia,and Bacteroides.These findings collectively suggest that Fu brick tea could alleviate MetS and MetS-associated traits with the mechanism relevant to the protection of intestinal barrier and gut microbiota regulation.展开更多
This study evaluates the influence of sand content on the mechanical behavior and water resistance of compressed earth bricks(CEBs)manufactured from Lendi clay(Douala,Cameroon).Twenty-seven specimens(prismatic and cub...This study evaluates the influence of sand content on the mechanical behavior and water resistance of compressed earth bricks(CEBs)manufactured from Lendi clay(Douala,Cameroon).Twenty-seven specimens(prismatic and cubic)were produced with three formulations:0%,30%and 60%sand substitution by dry mass,compacted at 2.5 MPa and cured for 7,14 and 28 days.Raw material characterization included particle size distribution,sand equivalent,Atterberg limits,bulk density and Proctor compaction.The clay displayed a liquid limit of 44.07%,plastic limit of 35.23%and plasticity index of 8.84%;optimum moisture content was 15.9%and maximum dry density 1.24 g·cm^(-3).Mechanical testing showed that pure-clay bricks achieved the highest compressive and flexural strengths at all ages(up to≈1.98 MPa and 0.56 MPa respectively).Although the 30%sand mix exhibited marginally higher early compressive strength(7 days),strength decreased substantially by 28 days.Capillary absorption tests revealed an important distinction:while 0%sand bricks exhibited continuous water uptake,they retained cohesion during immersion;conversely,30%and 60%sand bricks disintegrated into a slurry within seconds of immersion,evidencing severe loss of internal bonding.These findings indicate that,for this highly plastic tropical clay,sand acts primarily as a microstructural diluent that undermines long-term cohesion and durability despite short-term packing benefits.The study underscores the need for locally tailored formulations or stabilizers when designing durable CEBs for humid tropical climates.展开更多
With brick-wall solar greenhouses in Changli area as the research object,using temperature dynamic monitoring and statistical methods,the greenhouse structure suitable for promoting early cultivation of local peach tr...With brick-wall solar greenhouses in Changli area as the research object,using temperature dynamic monitoring and statistical methods,the greenhouse structure suitable for promoting early cultivation of local peach trees was selected by studying the temperature data of the solar greenhouses during the winter solstice,and a prediction model for daily average temperature was constructed.The results showed that greenhouse Ⅰ had reasonable structural parameters and good daylight during the day.However,due to the low wall thickness and poor insulation material,the minimum temperature was significantly lower than other greenhouses.The thermal insulation performance of greenhouse Ⅱ and Ⅲ was better than that of greenhouse Ⅰ,but the depth-span ratio and the front roof lighting angle were smaller.During the winter solstice,the average temperature of the three greenhouses was between 10 and 15℃,which was suitable for early cultivation of peach trees.The prediction model of daily average temperature was obtained:Daily average temperature=1.02+0.69×Daily average temperature of the previous day+0.02×Maximum temperature of the previous day-0.01×Minimum temperature of the previous day.To sum up,the structural parameters of brick-wall solar greenhouses suitable for early cultivation of peach trees in Changli area were as follows:span 6.5-8.5 m,depth-span ratio 0.47,front roof lighting angle 30°and wall thickness greater than 55 cm.展开更多
In order to improve the efficient and high-value recycling utilization rate of waste red bricks from construction waste,this study crushed and ground the waste red bricks to produce recycled brick powder(RBP)with diff...In order to improve the efficient and high-value recycling utilization rate of waste red bricks from construction waste,this study crushed and ground the waste red bricks to produce recycled brick powder(RBP)with different fineness,used the Andreasen model to explore the influence of RBP on the compact filling effect of cementitious material system based on the basic characteristics of RBP.The influence of grinding time(10,20,30 min)and content(0%,5%,10%,15%,20%)of RBP on the macroscopic mechanical properties of cementitious materials was investigated.We analyzed the significant impact of RBP particle characteristics on the compressive strength of the specimen with the aid of grey entropy theory,and revealed the influence mechanism of RBP on the microstructure of cementitious materials by scanning electron microscope(SEM)and nuclear magnetic resonance(NMR).The results show that the fineness of RBP after grinding is smaller than that of cement.The fineness of recycled brick powder increases gradually with the extension of grinding time,which is manifested as the increase of<3μm particles and the decrease of>18μm particles.Compared with the unitary cement cementitious material system,the particle gradation of the RBP-cement binary cementitious material system is closer to the closest packing state.With the increase of RBP content and grinding time,the compactness of the binary cementitious system gradually decreases,indicating that the incorporation of RBP reduces the mechanical strength of the specimen.The results of grey entropy show that the specific surface area D(0.1)and<45μm particles are the significant factors affecting the mechanical properties of cementitious materials mixed with RBP.RBP mainly affects the macroscopic properties of cementitious materials by affecting the internal compactness,the number of hydration products and the pore structure.The results of SEM show that when the RBP content is less than 15%,the content of C-S-H in cement paste increase,and the content of Ca(OH)2 decreases,and the content of C-S-H decreases and the content of Ca(OH)2 increases when the RBP content is more than 15%.The NMR results show that with the extension of grinding time,the pore size of micropore increases gradually,that of middle-small pores decreases gradually,and that of large pores remains unchanged.With the increase of RBP content,the micropores first decrease and then increase,and the middle-small pores and large pores gradually decrease.In summary,the compactness of cementitious material system can be improved by adjusting the fineness of RBP.Considering the performance of cementitious materials and the utilization rate of RBP,it is recommended that the grinding time of RBP is 20 min and the content is 10%-15%.展开更多
In order to study the effects of the contents of used mortar recycled aggregate(OMRA)and brick recycled aggregate(BRA)on the deformation properties of recycled aggregate concrete(RAC),under uniaxial compression condit...In order to study the effects of the contents of used mortar recycled aggregate(OMRA)and brick recycled aggregate(BRA)on the deformation properties of recycled aggregate concrete(RAC),under uniaxial compression conditions,The RAC of OMRA(0%,5%,10%,and 15%)and BRA(0%,3%,6%,9%,12%,and 15%)were studied.The experimental results show that,under uniaxial compression,the interfacial relationships of RAC containing OMRA and BRA between different materials are more complex,and the failure mechanism is also more complex.The content of OMRA and BRA had significant influence on the deformation behavior of RAC.When the content of OMRA and BRA is high,it is difficult for existing formulas and models to accurately represent the actual value.In this study,the influence of OMRA and BRA content is taken into account,and the existing formulas for calculating concrete deformation are modified,so that these formulas can more accurately calculate the elastic modulus,peak strain and ultimate strain of recycled concrete.The stress-strain formula of Guo concrete fits the stress-strain curve of concrete very well.We modified the formula on the basis of Guo formula to make the formula more suitable for the stress-strain curve of recycled concrete containing old mortar and brick,and the theoretical model proposed has better fitting accuracy.The study provides a valuable reference for nonlinear analysis of recycled aggregate concrete structures under different proportions of OMRA and BRA.展开更多
This study explores the novel application of Triumfetta pentandra(TP,“Nkui”)fibers,a tropical plant that is abundant yet underutilized in civil engineering,to enhance the performance of compressed earth bricks(CEBs)...This study explores the novel application of Triumfetta pentandra(TP,“Nkui”)fibers,a tropical plant that is abundant yet underutilized in civil engineering,to enhance the performance of compressed earth bricks(CEBs).The main objective is to assess how incorporating these vegetal fibers can improve the mechanical properties of CEBs while maintaining durability.TP fibers were extracted,characterized,and integrated into the soil used for brick specimens.A rigorous experimental protocol was implemented,featuring a unique fiber pre-treatment,the use of a single,homogeneous clayey soil type,and controlled 28-day curing under standard humidity and temperature,which distinguishes this study from previous works.Physical measurements(moisture content,bulk density,water absorption)and mechanical tests(fiber tensile strength,compressive and flexural strength of CEBs)were conducted following French standards.The results indicate that 4%TP fiber content yields optimal mechanical performance,with compressive strength reaching 6.61 MPa and flexural strength 1.49 MPa at 28 days,compared to 5.16 MPa and 0.51 MPa for unreinforced samples.This demonstrates the potential of TP fibers to reinforce earth-based materials,providing a sustainable,locally sourced,and cost-effective construction solution.However,higher fiber content increases porosity and capillary water absorption(up to 16.75 g at 6%fibers),highlighting the importance of optimized fiber dosing and potential complementary treatments for long-term durability.展开更多
建立了由一个制造商和一个分销商组成的基于电子市场的二级供应链模型,讨论了分销商采用Bricks and Clicks模式分销产品,并在电子渠道进行季节后销售的情况,分析了供应链的契约协调问题及供应链成员的利润情况.研究发现改进的回购契约...建立了由一个制造商和一个分销商组成的基于电子市场的二级供应链模型,讨论了分销商采用Bricks and Clicks模式分销产品,并在电子渠道进行季节后销售的情况,分析了供应链的契约协调问题及供应链成员的利润情况.研究发现改进的回购契约可以使Bricks and Clicks分销模式下基于电子市场的二级供应链模型达到协调,使分销商的订货量达到供应链最优,并且使供应链成员的利润达到Pareto改进,达到"双赢".最后,通过算例验证了结论.展开更多
In order to promote the quality of brick tea and reduce its fluoride content, the fluoride contents in leaves of 25 tea varieties at the .stage of one bud and five leaves were determined by the method of fluodde-ion s...In order to promote the quality of brick tea and reduce its fluoride content, the fluoride contents in leaves of 25 tea varieties at the .stage of one bud and five leaves were determined by the method of fluodde-ion selective electrode method. The results showed that the fluodde contents in the 25 varieties were in the range of 181.92-345.06 mg/kg, end the fluoride content in ＇Zhongcha 302＇ was the lowest. Based on traditional production process of brick tea, 3 new low-fluoride brick tea production processes with ＇Zhongcha 302＇ as the raw material at the stage of one bud and five leaves were constructed. The fluoride content, physicochemical in- dex, sensory end main chemical contents in the brick tea samples were determined. The best processing process of Iow-fluodde brick tea was process 3, which included aldng, fixing, rolling, second fixing, second roiling, sun-drying, pile-fermentation, steaming, pile-fermentation, drying and shaping into brick by vapor treating. The re- sults showed that the fluoride content and physicochemical index of the brick tea sample of the third low-fluoride brick tea production process accorded with National Standard GB/T 9833.4-2013. The sensory evaluation of the brick tea sample was better than that of brick tea manufacture by the traditional process. The water extract, tea polyphenols, amino acids, caffeine and water-soluble sugar in the brick tea sample increased by 9.41%, 36.39%, 26.94%, 27.23% and 15.29%, respectively. Low-fluodds bdck tea could be produced by selecting low fluoride tea varieties, controlling the tondemess of fresh leaves, and optimizing the processing technique.展开更多
In the paper, the effects of nutrition lick brick and salt brick as supple-ment feed on the performance of Tan sheep were studied. 36 fattening Tan sheep with the average weight of about 23 kg were chosen, they were r...In the paper, the effects of nutrition lick brick and salt brick as supple-ment feed on the performance of Tan sheep were studied. 36 fattening Tan sheep with the average weight of about 23 kg were chosen, they were randomly divided into 3 groups according to the weight, and each group had 12 sheep. Control group was fed with normal daily ration, experimental group 1 was fed with normal daily ration＋nutrition lick brick, experimental group 2 was fed with normal daily ration＋salt brick, the experimental period was 60 d. The results showed that 1） compared with CK, daily gain of group 1 improved 17.09%（P〈0.01）, feed conversion ratio reduced 11.69%（P〈0.05）, and average gross profit per sheep improved 51.65 yuan; daily gain of group 2 improved 7.03%（P〈0.05）, feed conversion ratio reduced 4.06%（P〉0.05）, and average gross profit per sheep improved 19.78 yuan; 2） compared with group 2, daily gain of group 1 improved 9.40%（P〈0.05）, feed conversion ratio re-duced 7.96%（P〈0.05）, and average gross profit per sheep improved 31.87 yuan;these indicated that nutrition lick brick and salt brick as supplement feed for Tan sheep both can improve the production performance of Tan sheep, and the supple-mentary feeding effect of nutrition lick brick was better.展开更多
文摘The aim of this study is to enhance the value of local earth materials used in the construction of certain homes in the Republic of Guinea. Thus, a trial study to improve the quality of mud bricks using paper fibers obtained by grinding and soaking in water and then drying were used as a stabilizer in the manufacture of these mud bricks from the sample of two sites Dounkiwal (DK) (in Mamou and the sample from the urban commune of Kouroussa). To do this, certain methods and means of identification were carried out, namely: geotechnical, mineralogical and chemical analyses. Sample DK from Mamou has a silty-clay geotechnical characteristic with a plasticity index Ip of 12.75%. However, mineralogical and chemical studies showed that sample Dounkiwal (DK) (Mamou) contains a high proportion of silica and iron oxides (79.63%) and Fe2O3 (11.85%), associated with other alkaline earth oxides and ions: CaO;MgO;SO32−;Cl−, i.e. 3.96%;0.96%;0.28% and 0.039% respectively. Its loss on ignition (LOI) and insoluble residues are 15.40% and 56.36%. The evaluation of the number of huts in Upper and Middle Guinea showed that the populations of these areas have been using mud bricks for several decades in the construction of dwellings. The average value found for the compressive strength of these bricks (from samples I, II and III from Kouroussa) is 0.16 MPa. This value is appreciable in the construction of mud houses.
文摘This study was part of the framework that contributed not only to the improvement of thermal comfort in housing but also to the decarbonization of the construction and building materials industry. For this purpose, terracotta brick seems to meet these needs. Thus, the objective of this work was to evaluate the influence of the incorporation of coal fly ash from a thermal power plant on the physical and mechanical properties of fired bricks from grey clay in the Thicky area of Senegal. The coal fly ash was incorporated into the raw clay material in proportions of 0, 5, 10, and 15 % by weight. These two raw materials were first characterized by X-ray fluorescence spectroscopy (XRF). The XRF analyses showed that the most abundant oxides in clay were SiO2 (55.034%) and Fe2O3 (10.155%). In coal fly ash, SiO2 (38.574%) is predominant. The ash also contained Al2O3 (7.717%) and alicano-earthy melting oxides such as CaO (9.271%) and MgO (7.298%) etc. These melting oxides were necessary to facilitate the formation of the liquid phase when baking platelets. The latter, when burned at a temperature of 880°C, were characterized by determining the number of physico-mechanical parameters, such as linear shrinkage during cooking, water absorption, fire loss and compressive strength. A Hierarchical Ascending Classification of these different parameters was performed and three classes were obtained. Class 1 with better compressive strength (6.358 MPa), was in sample A (5%). Class 2 consisted of sample D (reference) and had a higher plasticity index (28.51%) and water absorption rate (11.19%). Finally, class 3, which included samples B (10%) and C (15%), had very high shrinkage and fire losses compared to other platelets. These results highlighted the possibility of using up to 5% of the coal fly ash in the production of new fired bricks with good performance.
基金supported by the Earmarked Fund for the Modern Agricultural Industry Technology System(CARS19),Research on Quality Chemical Characteristics and Healthy Function of Xianyang Brick Tea(2021kjc-js231)Research on Metabolite Alteration and Mechanism in Fu Brick Tea under the Action of Eurotium cristatum(31471706).
文摘This study investigated the therapeutic effects on metabolic syndrome(MetS)and the impact on the intestinal barrier and gut microbiota of Fu brick tea aqueous extracts(FTE)on MetS in rats fed with a high-fat diet(HFD).Here,the results showed that FTE supplement significantly reduced HFD-induced weight gain,adiposity,dyslipidemia,fasting blood glucose(FBG)increment,and non-alcoholic fatty liver disease(NAFLD).Moreover,FTE supplement resulted in a decline in lipopolysaccharide(LPS)level and attenuation of colonic inflammation and oxidative stress to protect the intestinal barrier function.FTE supplement also maintained the intestinal barrier integrity by improving histological appearance and promoting ZO-1,Occludin,and Claudin-1 protein expression levels.Meanwhile,FTE supplement alleviated the gut microbiota dysbiosis by enhancing the Firmicutes/Bacteroidetes(F/B)ratio and stimulating the colonization of probiotic bacteria such as Akkermansia,Lactobacillus,Adlercreutzia,and Bacteroides.These findings collectively suggest that Fu brick tea could alleviate MetS and MetS-associated traits with the mechanism relevant to the protection of intestinal barrier and gut microbiota regulation.
文摘This study evaluates the influence of sand content on the mechanical behavior and water resistance of compressed earth bricks(CEBs)manufactured from Lendi clay(Douala,Cameroon).Twenty-seven specimens(prismatic and cubic)were produced with three formulations:0%,30%and 60%sand substitution by dry mass,compacted at 2.5 MPa and cured for 7,14 and 28 days.Raw material characterization included particle size distribution,sand equivalent,Atterberg limits,bulk density and Proctor compaction.The clay displayed a liquid limit of 44.07%,plastic limit of 35.23%and plasticity index of 8.84%;optimum moisture content was 15.9%and maximum dry density 1.24 g·cm^(-3).Mechanical testing showed that pure-clay bricks achieved the highest compressive and flexural strengths at all ages(up to≈1.98 MPa and 0.56 MPa respectively).Although the 30%sand mix exhibited marginally higher early compressive strength(7 days),strength decreased substantially by 28 days.Capillary absorption tests revealed an important distinction:while 0%sand bricks exhibited continuous water uptake,they retained cohesion during immersion;conversely,30%and 60%sand bricks disintegrated into a slurry within seconds of immersion,evidencing severe loss of internal bonding.These findings indicate that,for this highly plastic tropical clay,sand acts primarily as a microstructural diluent that undermines long-term cohesion and durability despite short-term packing benefits.The study underscores the need for locally tailored formulations or stabilizers when designing durable CEBs for humid tropical climates.
基金Supported by Modern Agricultural Industry Technology System Innovation Team Construction in Hebei Province(HBCT2023130404).
文摘With brick-wall solar greenhouses in Changli area as the research object,using temperature dynamic monitoring and statistical methods,the greenhouse structure suitable for promoting early cultivation of local peach trees was selected by studying the temperature data of the solar greenhouses during the winter solstice,and a prediction model for daily average temperature was constructed.The results showed that greenhouse Ⅰ had reasonable structural parameters and good daylight during the day.However,due to the low wall thickness and poor insulation material,the minimum temperature was significantly lower than other greenhouses.The thermal insulation performance of greenhouse Ⅱ and Ⅲ was better than that of greenhouse Ⅰ,but the depth-span ratio and the front roof lighting angle were smaller.During the winter solstice,the average temperature of the three greenhouses was between 10 and 15℃,which was suitable for early cultivation of peach trees.The prediction model of daily average temperature was obtained:Daily average temperature=1.02+0.69×Daily average temperature of the previous day+0.02×Maximum temperature of the previous day-0.01×Minimum temperature of the previous day.To sum up,the structural parameters of brick-wall solar greenhouses suitable for early cultivation of peach trees in Changli area were as follows:span 6.5-8.5 m,depth-span ratio 0.47,front roof lighting angle 30°and wall thickness greater than 55 cm.
基金Funded by National Natural Science Foundation of China(No.52108219)Lanzhou University of Technology Hongliu Outstanding Young Talent Program,China(No.062407)The High Quality of Green Machine-made Aggregate and the Evolution Mechanism of Concrete Life Cycle Performance in the Harsh Environment of Northwest China(No.U21A20150)。
文摘In order to improve the efficient and high-value recycling utilization rate of waste red bricks from construction waste,this study crushed and ground the waste red bricks to produce recycled brick powder(RBP)with different fineness,used the Andreasen model to explore the influence of RBP on the compact filling effect of cementitious material system based on the basic characteristics of RBP.The influence of grinding time(10,20,30 min)and content(0%,5%,10%,15%,20%)of RBP on the macroscopic mechanical properties of cementitious materials was investigated.We analyzed the significant impact of RBP particle characteristics on the compressive strength of the specimen with the aid of grey entropy theory,and revealed the influence mechanism of RBP on the microstructure of cementitious materials by scanning electron microscope(SEM)and nuclear magnetic resonance(NMR).The results show that the fineness of RBP after grinding is smaller than that of cement.The fineness of recycled brick powder increases gradually with the extension of grinding time,which is manifested as the increase of<3μm particles and the decrease of>18μm particles.Compared with the unitary cement cementitious material system,the particle gradation of the RBP-cement binary cementitious material system is closer to the closest packing state.With the increase of RBP content and grinding time,the compactness of the binary cementitious system gradually decreases,indicating that the incorporation of RBP reduces the mechanical strength of the specimen.The results of grey entropy show that the specific surface area D(0.1)and<45μm particles are the significant factors affecting the mechanical properties of cementitious materials mixed with RBP.RBP mainly affects the macroscopic properties of cementitious materials by affecting the internal compactness,the number of hydration products and the pore structure.The results of SEM show that when the RBP content is less than 15%,the content of C-S-H in cement paste increase,and the content of Ca(OH)2 decreases,and the content of C-S-H decreases and the content of Ca(OH)2 increases when the RBP content is more than 15%.The NMR results show that with the extension of grinding time,the pore size of micropore increases gradually,that of middle-small pores decreases gradually,and that of large pores remains unchanged.With the increase of RBP content,the micropores first decrease and then increase,and the middle-small pores and large pores gradually decrease.In summary,the compactness of cementitious material system can be improved by adjusting the fineness of RBP.Considering the performance of cementitious materials and the utilization rate of RBP,it is recommended that the grinding time of RBP is 20 min and the content is 10%-15%.
基金Funded by the Project of National Key Research and Development Program of China(No.2019YFC1906202)。
文摘In order to study the effects of the contents of used mortar recycled aggregate(OMRA)and brick recycled aggregate(BRA)on the deformation properties of recycled aggregate concrete(RAC),under uniaxial compression conditions,The RAC of OMRA(0%,5%,10%,and 15%)and BRA(0%,3%,6%,9%,12%,and 15%)were studied.The experimental results show that,under uniaxial compression,the interfacial relationships of RAC containing OMRA and BRA between different materials are more complex,and the failure mechanism is also more complex.The content of OMRA and BRA had significant influence on the deformation behavior of RAC.When the content of OMRA and BRA is high,it is difficult for existing formulas and models to accurately represent the actual value.In this study,the influence of OMRA and BRA content is taken into account,and the existing formulas for calculating concrete deformation are modified,so that these formulas can more accurately calculate the elastic modulus,peak strain and ultimate strain of recycled concrete.The stress-strain formula of Guo concrete fits the stress-strain curve of concrete very well.We modified the formula on the basis of Guo formula to make the formula more suitable for the stress-strain curve of recycled concrete containing old mortar and brick,and the theoretical model proposed has better fitting accuracy.The study provides a valuable reference for nonlinear analysis of recycled aggregate concrete structures under different proportions of OMRA and BRA.
文摘This study explores the novel application of Triumfetta pentandra(TP,“Nkui”)fibers,a tropical plant that is abundant yet underutilized in civil engineering,to enhance the performance of compressed earth bricks(CEBs).The main objective is to assess how incorporating these vegetal fibers can improve the mechanical properties of CEBs while maintaining durability.TP fibers were extracted,characterized,and integrated into the soil used for brick specimens.A rigorous experimental protocol was implemented,featuring a unique fiber pre-treatment,the use of a single,homogeneous clayey soil type,and controlled 28-day curing under standard humidity and temperature,which distinguishes this study from previous works.Physical measurements(moisture content,bulk density,water absorption)and mechanical tests(fiber tensile strength,compressive and flexural strength of CEBs)were conducted following French standards.The results indicate that 4%TP fiber content yields optimal mechanical performance,with compressive strength reaching 6.61 MPa and flexural strength 1.49 MPa at 28 days,compared to 5.16 MPa and 0.51 MPa for unreinforced samples.This demonstrates the potential of TP fibers to reinforce earth-based materials,providing a sustainable,locally sourced,and cost-effective construction solution.However,higher fiber content increases porosity and capillary water absorption(up to 16.75 g at 6%fibers),highlighting the importance of optimized fiber dosing and potential complementary treatments for long-term durability.
文摘建立了由一个制造商和一个分销商组成的基于电子市场的二级供应链模型,讨论了分销商采用Bricks and Clicks模式分销产品,并在电子渠道进行季节后销售的情况,分析了供应链的契约协调问题及供应链成员的利润情况.研究发现改进的回购契约可以使Bricks and Clicks分销模式下基于电子市场的二级供应链模型达到协调,使分销商的订货量达到供应链最优,并且使供应链成员的利润达到Pareto改进,达到"双赢".最后,通过算例验证了结论.
文摘In order to promote the quality of brick tea and reduce its fluoride content, the fluoride contents in leaves of 25 tea varieties at the .stage of one bud and five leaves were determined by the method of fluodde-ion selective electrode method. The results showed that the fluodde contents in the 25 varieties were in the range of 181.92-345.06 mg/kg, end the fluoride content in ＇Zhongcha 302＇ was the lowest. Based on traditional production process of brick tea, 3 new low-fluoride brick tea production processes with ＇Zhongcha 302＇ as the raw material at the stage of one bud and five leaves were constructed. The fluoride content, physicochemical in- dex, sensory end main chemical contents in the brick tea samples were determined. The best processing process of Iow-fluodde brick tea was process 3, which included aldng, fixing, rolling, second fixing, second roiling, sun-drying, pile-fermentation, steaming, pile-fermentation, drying and shaping into brick by vapor treating. The re- sults showed that the fluoride content and physicochemical index of the brick tea sample of the third low-fluoride brick tea production process accorded with National Standard GB/T 9833.4-2013. The sensory evaluation of the brick tea sample was better than that of brick tea manufacture by the traditional process. The water extract, tea polyphenols, amino acids, caffeine and water-soluble sugar in the brick tea sample increased by 9.41%, 36.39%, 26.94%, 27.23% and 15.29%, respectively. Low-fluodds bdck tea could be produced by selecting low fluoride tea varieties, controlling the tondemess of fresh leaves, and optimizing the processing technique.
文摘In the paper, the effects of nutrition lick brick and salt brick as supple-ment feed on the performance of Tan sheep were studied. 36 fattening Tan sheep with the average weight of about 23 kg were chosen, they were randomly divided into 3 groups according to the weight, and each group had 12 sheep. Control group was fed with normal daily ration, experimental group 1 was fed with normal daily ration＋nutrition lick brick, experimental group 2 was fed with normal daily ration＋salt brick, the experimental period was 60 d. The results showed that 1） compared with CK, daily gain of group 1 improved 17.09%（P〈0.01）, feed conversion ratio reduced 11.69%（P〈0.05）, and average gross profit per sheep improved 51.65 yuan; daily gain of group 2 improved 7.03%（P〈0.05）, feed conversion ratio reduced 4.06%（P〉0.05）, and average gross profit per sheep improved 19.78 yuan; 2） compared with group 2, daily gain of group 1 improved 9.40%（P〈0.05）, feed conversion ratio re-duced 7.96%（P〈0.05）, and average gross profit per sheep improved 31.87 yuan;these indicated that nutrition lick brick and salt brick as supplement feed for Tan sheep both can improve the production performance of Tan sheep, and the supple-mentary feeding effect of nutrition lick brick was better.
