Purpose-The utilization of alkali-free accelerators,primarily based on aluminum sulfate,in shotcrete often leads to significant shrinkage and cracking,jeopardizing long-term durability.This study aims to mitigate this...Purpose-The utilization of alkali-free accelerators,primarily based on aluminum sulfate,in shotcrete often leads to significant shrinkage and cracking,jeopardizing long-term durability.This study aims to mitigate this issue by investigating the efficacy of silica fume(SF)and fly ash(FA),individually and combined,in controlling the shrinkage deformation of shotcrete.Design/methodology/approach-Shotcrete mixtures were prepared with cement partially replaced by SF,FA,or their combination(SF-FA).Aluminum sulfate was used as an accelerator.The shrinkage behavior under sealed and dry conditions was monitored.The underlying mechanisms were elucidated through hardened airvoid analysis,mercury intrusion porosimetry(MIP),and internal humidity tracking.Findings-Contrary to some previous studies,both individual and combined incorporation of mineral admixtures reduced the 28-day shrinkage.The SF-FA composite exhibited the most substantial reduction(23.72%sealed,17.76%dry),followed by SF alone(18.11%sealed)and FA alone(11.35%sealed).Mechanism analysis revealed that the admixtures refined the pore structure,reduced the volume of harmful pores,and,crucially,optimized the air-void system by increasing the population of fine bubbles.This created an internal buffering effect that alleviates capillary stress.The synergistic effect in the SF-FA group is attributed to complementary pore-filling at dual scales.Originality/value-This work demonstrates that,within an aluminum sulfate-accelerated shotcrete system,silica fume can effectively reduce shrinkage when its pore-refining effect is counterbalanced by a welloptimized micro-bubble network.It provides the first comprehensive evidence of the synergistic shrinkagereducing mechanism of SF and FA in such systems,offering a practical strategy for mix design optimization to enhance the volume stability of shotcrete.展开更多
This study investigated the factors contributing to intravenous admixture preparation errors(IAPEs)within Pharmacy Intravenous Admixture Services(PIVAS).A retrospective analysis was conducted on IAPEs documented in th...This study investigated the factors contributing to intravenous admixture preparation errors(IAPEs)within Pharmacy Intravenous Admixture Services(PIVAS).A retrospective analysis was conducted on IAPEs documented in the PIVAS unit of a large multi-specialty hospital in China,which houses over 2000 beds,covering the period from January 1,2015 to December 31,2022.Drug preparation records were examined using a generalized linear mixed model(GLMM)to identify both univariate and multivariate factors associated with IAPE occurrences.A total of 824 IAPE cases were recorded during the study period,yielding an overall error rate of 0.018%.Univariate analysis identified drug categories(general drugs,anti-infective drugs,and antineoplastic drugs),preparation time(workdays),and years of work experience as significant determinants(P<0.05).Multivariate analysis further confirmed that drug categories(general and antineoplastic drugs),preparation time(workdays),and work experience remained statistically significant predictors of IAPE incidence(P<0.05).IAPEs in PIVAS were influenced by multiple factors,predominantly those related to personnel and drug characteristics.Targeted interventions,informed by multivariate analysis,are essential to mitigating these errors and enhancing medication safety.展开更多
Crystalline admixtures(CA),also known as permeability reducer admixtures,are used in binder-based materials to improve concrete durability by reducing water permeability depth,increasing compressive strength,and stimu...Crystalline admixtures(CA),also known as permeability reducer admixtures,are used in binder-based materials to improve concrete durability by reducing water permeability depth,increasing compressive strength,and stimulating crack healing.The purpose of this study is to evaluate the potential of crystalline admixtures to enhance the self-healing characteristics and durability attributes of concrete and to contribute to the understanding of their role in the design of long-term efficiency and sustainability.The 28 days specimens of M40 grade concrete were prepared by adding CA and cast as 150 mm cubes,25×25×285 mm prisms and disks with a diameter of 100 mm and height of 50 mm.All samples were then tested for compressive strength,water permeability,dry shrinkage,sodium sulfate attack test,Rapid Chloride Migration Test(RCMT),and rapid chloride penetration test(RCPT)to study the behavior of incorporating crystalline admixtures in concrete.The conclusion drawn from this study was that the addition of a crystalline admixture of 0.8%resulted in an increase in the compressive strength by 7.98%and a decrease in water penetration depth through the cube by 71.5%,while the dry shrinkage of the specimen incorporated with the crystalline admixture was 65.21%less than that of the specimen without the crystalline admixture.These results substantiate the beneficial role of CA in increasing the durability of concrete through increased strength,lower permeability,and better dimensional stability,thus making crystalline admixtures beneficial for incorporation into high-performance concrete applications.展开更多
Four typical admixtures,polycarboxylate superplasticiser(PCE),tartaric acid(TA),sorbitol and polyacrylamide(PAM),were selected to systematically investigate their regulatory mechanisms on the formation of ettringite t...Four typical admixtures,polycarboxylate superplasticiser(PCE),tartaric acid(TA),sorbitol and polyacrylamide(PAM),were selected to systematically investigate their regulatory mechanisms on the formation of ettringite through Fourier transform infrared spectroscopy,X-ray diffraction,particle size analysis and nucleation kinetic model.The experimental results indicate that the admixtures alter the formation of ettringite through physical adsorption,complexation and solution viscosity modulation without changing its chemical structure.Low concentrations of PCE inhibit size growth by forming an adsorption layer on the surface of ettringite,whereas high concentrations of PCE alter the size change of ettringite by modulating the distribution of ionic concentrations.TA significantly reduces the size of ettringite by complexing Ca^(2+).Sorbitol and PAM promote the local growth of ettringite at low concentrations,leading to larger sizes.But at high concentrations,the size growth of ettringite is inhibited due to the increase in viscosity or the enhancement of complexation.Matlab nucleation kinetic modelling further shows that the addition of admixtures enhances the initial nucleation during ettringite synthesis,with values ranging from 14.45%to 114.25%.However,the subsequent nucleation rate of ettringite is significantly affected,decreasing by 12.79%to 71.74%.The results provide a theoretical basis for the design of ettringite materials and the optimisation of the application of admixtures.展开更多
An evaluation method for self-healing capacity was designed,which includes the control of initial cracks and subsequent permeability testing.This method was employed to evaluate the self-healing behavior of mortars in...An evaluation method for self-healing capacity was designed,which includes the control of initial cracks and subsequent permeability testing.This method was employed to evaluate the self-healing behavior of mortars incorporating crystalline admixtures(CAs)under various conditions,including water immersion,limewater soaking,and wet-dry cycles,with varying CA dosages and crack widths.The experimental results indicate that cement possesses inherently self-healing capability.Limewater environments inhibits healing compared with water immersion;however,wet-dry cycles enhance the effectiveness of higher CA dosages.Increasing the CA content can not improve healing performance,and wide cracks(0.3 mm)substantially reduce the intrinsic self-healing potential of cement.展开更多
In this paper,the effects of four different mineral ginseng materials on the mechanical properties of mortar were studied,and the results showed that high territory,fly ash,and silica fume had an inhibitory effect on ...In this paper,the effects of four different mineral ginseng materials on the mechanical properties of mortar were studied,and the results showed that high territory,fly ash,and silica fume had an inhibitory effect on the drying shrinkage of mortar,and mineral powder increased the drying shrinkage of mortar.The high territory in the mineral admixture has the best effect on the inhibition of mortar drying shrinkage.The compressive strength and flexural strength of the mortar can be improved by adding a certain amount of mineral admixture,which increases the compressive strength by about 20%-40%and the flexural strength by about 20%-30%compared with the control group,and the improvement effect difference between different components is not large.展开更多
In the present study, we aimed to analyze the irrational medical orders and evaluate the effect of pharmacy intervention on pharmacy intravenous admixture services of outpatient and emergency departments in our hospit...In the present study, we aimed to analyze the irrational medical orders and evaluate the effect of pharmacy intervention on pharmacy intravenous admixture services of outpatient and emergency departments in our hospital. The irrational medical orders of PIVAS at the outpatient and emergency departments were retrospectively analyzed in Jun. 2015. We strengthened the pharmacy intervention on irrational medical orders since July 2015. All the cases were selected by systematic sampling method. Cased studied in Jun. 2015 served as the control group, whereas those studied in Jan. 2016 served as the intervention group. The irrational rate and the irrational number of daily average were compared between the control group and intervention group. The common type of irrational outpatient and emergency intravenous orders mainly included irrational use of solvents, irrational dosing interval and inappropriate compatibility of drugs. The irrational rate was reduced from 17.4% to 3.3% （P〈0.01）, and the irrational number of daily average was decreased from 5.23 to 1.00 （P〈0.01）. Pharmacy intervention can reduce the irrational rate of medical orders in our hospital, which is of great significance to promote rational drug use and improve medical quality.展开更多
The expansion and micro-cracks of the mortar with composite mineral admixtures （fly ash, zeolite and slag） due to the alkali-silica reaction （ASR） are studied. Results show that composite mineral admixtures cannot...The expansion and micro-cracks of the mortar with composite mineral admixtures （fly ash, zeolite and slag） due to the alkali-silica reaction （ASR） are studied. Results show that composite mineral admixtures cannot absolutely diminish the ASR of mortar bars with the low-alkali cement and a highly reactive aggregate. But the expansion rate and the deleterious expansion of the mortar bar are mostly reduced with increasing composite mineral admixture. The influence of mineral admixtures on the fluidity of the paste and the strength of the mortar is also studied.展开更多
The rice husk ash （ RHA） and silica （ Si02） nanoparticles are prepared from rice husk charcoal （RHC） by the methods of ventilated calcining and chemical precipitation, respectively, to remove the residual carbon...The rice husk ash （ RHA） and silica （ Si02） nanoparticles are prepared from rice husk charcoal （RHC） by the methods of ventilated calcining and chemical precipitation, respectively, to remove the residual carbon which is harmful to cement composites. The structures and morphologies of these products are investigated by the Fourier transform infrared spectroscopy, X-ray diffraction, scanning/ transmission electron microscopy and N2 adsorption- desorption analyzer. The results show that the as-produced RHA and Si02 nanoparticles exist in amorphous phase without residual carbon, and exhibit porous structures with specific surface areas of 170.19 and 248. 67 m2 /g , respectively. The micro particles of RHA are aggregated by numerous loosely packed Si02 gel particles with the diameter of 50 to 100 nm. The Si02 nanoparticles are well dispersed with the average size of about 30 nm. Both the RHA and Si02 nanoparticles can significantly reduce the conductivity of saturated Ca（OH）2 solution and increase the early strength of the cement composites. They also exhibit high pozzolanic activity, indicating that they can be used as ecological nano mineral admixtures.展开更多
文摘Purpose-The utilization of alkali-free accelerators,primarily based on aluminum sulfate,in shotcrete often leads to significant shrinkage and cracking,jeopardizing long-term durability.This study aims to mitigate this issue by investigating the efficacy of silica fume(SF)and fly ash(FA),individually and combined,in controlling the shrinkage deformation of shotcrete.Design/methodology/approach-Shotcrete mixtures were prepared with cement partially replaced by SF,FA,or their combination(SF-FA).Aluminum sulfate was used as an accelerator.The shrinkage behavior under sealed and dry conditions was monitored.The underlying mechanisms were elucidated through hardened airvoid analysis,mercury intrusion porosimetry(MIP),and internal humidity tracking.Findings-Contrary to some previous studies,both individual and combined incorporation of mineral admixtures reduced the 28-day shrinkage.The SF-FA composite exhibited the most substantial reduction(23.72%sealed,17.76%dry),followed by SF alone(18.11%sealed)and FA alone(11.35%sealed).Mechanism analysis revealed that the admixtures refined the pore structure,reduced the volume of harmful pores,and,crucially,optimized the air-void system by increasing the population of fine bubbles.This created an internal buffering effect that alleviates capillary stress.The synergistic effect in the SF-FA group is attributed to complementary pore-filling at dual scales.Originality/value-This work demonstrates that,within an aluminum sulfate-accelerated shotcrete system,silica fume can effectively reduce shrinkage when its pore-refining effect is counterbalanced by a welloptimized micro-bubble network.It provides the first comprehensive evidence of the synergistic shrinkagereducing mechanism of SF and FA in such systems,offering a practical strategy for mix design optimization to enhance the volume stability of shotcrete.
基金The National Natural Science Foundation of China(Grant No.72474013)the Beijing Health Technology Promotion Project(Grant No.BHTPP2024007)。
文摘This study investigated the factors contributing to intravenous admixture preparation errors(IAPEs)within Pharmacy Intravenous Admixture Services(PIVAS).A retrospective analysis was conducted on IAPEs documented in the PIVAS unit of a large multi-specialty hospital in China,which houses over 2000 beds,covering the period from January 1,2015 to December 31,2022.Drug preparation records were examined using a generalized linear mixed model(GLMM)to identify both univariate and multivariate factors associated with IAPE occurrences.A total of 824 IAPE cases were recorded during the study period,yielding an overall error rate of 0.018%.Univariate analysis identified drug categories(general drugs,anti-infective drugs,and antineoplastic drugs),preparation time(workdays),and years of work experience as significant determinants(P<0.05).Multivariate analysis further confirmed that drug categories(general and antineoplastic drugs),preparation time(workdays),and work experience remained statistically significant predictors of IAPE incidence(P<0.05).IAPEs in PIVAS were influenced by multiple factors,predominantly those related to personnel and drug characteristics.Targeted interventions,informed by multivariate analysis,are essential to mitigating these errors and enhancing medication safety.
文摘Crystalline admixtures(CA),also known as permeability reducer admixtures,are used in binder-based materials to improve concrete durability by reducing water permeability depth,increasing compressive strength,and stimulating crack healing.The purpose of this study is to evaluate the potential of crystalline admixtures to enhance the self-healing characteristics and durability attributes of concrete and to contribute to the understanding of their role in the design of long-term efficiency and sustainability.The 28 days specimens of M40 grade concrete were prepared by adding CA and cast as 150 mm cubes,25×25×285 mm prisms and disks with a diameter of 100 mm and height of 50 mm.All samples were then tested for compressive strength,water permeability,dry shrinkage,sodium sulfate attack test,Rapid Chloride Migration Test(RCMT),and rapid chloride penetration test(RCPT)to study the behavior of incorporating crystalline admixtures in concrete.The conclusion drawn from this study was that the addition of a crystalline admixture of 0.8%resulted in an increase in the compressive strength by 7.98%and a decrease in water penetration depth through the cube by 71.5%,while the dry shrinkage of the specimen incorporated with the crystalline admixture was 65.21%less than that of the specimen without the crystalline admixture.These results substantiate the beneficial role of CA in increasing the durability of concrete through increased strength,lower permeability,and better dimensional stability,thus making crystalline admixtures beneficial for incorporation into high-performance concrete applications.
基金Funded by the National Natural Science Foundation of China(Nos.51578412,51878479,52078372,and 52478272)the International Science and Technology Cooperation Project of the Key R&D Program of Science and Technology Innovation Yongjiang 2035(No.2024H023)。
文摘Four typical admixtures,polycarboxylate superplasticiser(PCE),tartaric acid(TA),sorbitol and polyacrylamide(PAM),were selected to systematically investigate their regulatory mechanisms on the formation of ettringite through Fourier transform infrared spectroscopy,X-ray diffraction,particle size analysis and nucleation kinetic model.The experimental results indicate that the admixtures alter the formation of ettringite through physical adsorption,complexation and solution viscosity modulation without changing its chemical structure.Low concentrations of PCE inhibit size growth by forming an adsorption layer on the surface of ettringite,whereas high concentrations of PCE alter the size change of ettringite by modulating the distribution of ionic concentrations.TA significantly reduces the size of ettringite by complexing Ca^(2+).Sorbitol and PAM promote the local growth of ettringite at low concentrations,leading to larger sizes.But at high concentrations,the size growth of ettringite is inhibited due to the increase in viscosity or the enhancement of complexation.Matlab nucleation kinetic modelling further shows that the addition of admixtures enhances the initial nucleation during ettringite synthesis,with values ranging from 14.45%to 114.25%.However,the subsequent nucleation rate of ettringite is significantly affected,decreasing by 12.79%to 71.74%.The results provide a theoretical basis for the design of ettringite materials and the optimisation of the application of admixtures.
基金Funded by the International Science and Technology Cooperation Project of the Key R&D Program of Science and Technology Innovation Yongjiang 2035。
文摘An evaluation method for self-healing capacity was designed,which includes the control of initial cracks and subsequent permeability testing.This method was employed to evaluate the self-healing behavior of mortars incorporating crystalline admixtures(CAs)under various conditions,including water immersion,limewater soaking,and wet-dry cycles,with varying CA dosages and crack widths.The experimental results indicate that cement possesses inherently self-healing capability.Limewater environments inhibits healing compared with water immersion;however,wet-dry cycles enhance the effectiveness of higher CA dosages.Increasing the CA content can not improve healing performance,and wide cracks(0.3 mm)substantially reduce the intrinsic self-healing potential of cement.
基金Hunan Provincial Department of Water Resources:Research on Formula Optimization and Performance Evaluation System of Ecological Concrete for River Water Quality Purification Based on the Dual Carbon Goal(Project No.:XSKJ2024064-44)。
文摘In this paper,the effects of four different mineral ginseng materials on the mechanical properties of mortar were studied,and the results showed that high territory,fly ash,and silica fume had an inhibitory effect on the drying shrinkage of mortar,and mineral powder increased the drying shrinkage of mortar.The high territory in the mineral admixture has the best effect on the inhibition of mortar drying shrinkage.The compressive strength and flexural strength of the mortar can be improved by adding a certain amount of mineral admixture,which increases the compressive strength by about 20%-40%and the flexural strength by about 20%-30%compared with the control group,and the improvement effect difference between different components is not large.
文摘In the present study, we aimed to analyze the irrational medical orders and evaluate the effect of pharmacy intervention on pharmacy intravenous admixture services of outpatient and emergency departments in our hospital. The irrational medical orders of PIVAS at the outpatient and emergency departments were retrospectively analyzed in Jun. 2015. We strengthened the pharmacy intervention on irrational medical orders since July 2015. All the cases were selected by systematic sampling method. Cased studied in Jun. 2015 served as the control group, whereas those studied in Jan. 2016 served as the intervention group. The irrational rate and the irrational number of daily average were compared between the control group and intervention group. The common type of irrational outpatient and emergency intravenous orders mainly included irrational use of solvents, irrational dosing interval and inappropriate compatibility of drugs. The irrational rate was reduced from 17.4% to 3.3% （P〈0.01）, and the irrational number of daily average was decreased from 5.23 to 1.00 （P〈0.01）. Pharmacy intervention can reduce the irrational rate of medical orders in our hospital, which is of great significance to promote rational drug use and improve medical quality.
文摘The expansion and micro-cracks of the mortar with composite mineral admixtures （fly ash, zeolite and slag） due to the alkali-silica reaction （ASR） are studied. Results show that composite mineral admixtures cannot absolutely diminish the ASR of mortar bars with the low-alkali cement and a highly reactive aggregate. But the expansion rate and the deleterious expansion of the mortar bar are mostly reduced with increasing composite mineral admixture. The influence of mineral admixtures on the fluidity of the paste and the strength of the mortar is also studied.
基金The Key Program of the National Natural Science Foundation of China(No.51438003)the National Basic Research Program of China(973 Program)(No.2015CB655105)
文摘The rice husk ash （ RHA） and silica （ Si02） nanoparticles are prepared from rice husk charcoal （RHC） by the methods of ventilated calcining and chemical precipitation, respectively, to remove the residual carbon which is harmful to cement composites. The structures and morphologies of these products are investigated by the Fourier transform infrared spectroscopy, X-ray diffraction, scanning/ transmission electron microscopy and N2 adsorption- desorption analyzer. The results show that the as-produced RHA and Si02 nanoparticles exist in amorphous phase without residual carbon, and exhibit porous structures with specific surface areas of 170.19 and 248. 67 m2 /g , respectively. The micro particles of RHA are aggregated by numerous loosely packed Si02 gel particles with the diameter of 50 to 100 nm. The Si02 nanoparticles are well dispersed with the average size of about 30 nm. Both the RHA and Si02 nanoparticles can significantly reduce the conductivity of saturated Ca（OH）2 solution and increase the early strength of the cement composites. They also exhibit high pozzolanic activity, indicating that they can be used as ecological nano mineral admixtures.
