This study focuses on the workability and compressive strength of ceramsite self-compacting concrete with fine aggregate partially substituted by steel slag sand(CSLSCC)to prevent the pollution of steel slag in the en...This study focuses on the workability and compressive strength of ceramsite self-compacting concrete with fine aggregate partially substituted by steel slag sand(CSLSCC)to prevent the pollution of steel slag in the environment.The SF,J-ring,visual stability index,and sieve analysis tests are primarily employed in this research to investigate the workability of freshly mixed self-compacting concrete containing steel slag at various steel slag sand replacement rates.The experiment results indicate that CSLSCC with the 20%volume percentage of steel slag(VPS)performs better workability,higher strength,and higher specific strength.The 7-day compressive strength of CSLSCC with the 0.4 of the water-binder ratio(W/B),decreases with the increase of steel slag content,while the 28-day compressive strength increases significantly.The ceramsite self-compacting concrete with good comprehensive performance can be obtained when the substitution rate of steel slag sand for fine aggregate is less than 20%(volume percentage).展开更多
A phosphine oxide-containing bio-based curing agent was synthesized by addition reaction between furan derivatives and diphenylphosphine oxide.The molecular structure of the as-prepared bio-based curing agent was conf...A phosphine oxide-containing bio-based curing agent was synthesized by addition reaction between furan derivatives and diphenylphosphine oxide.The molecular structure of the as-prepared bio-based curing agent was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy.Dynamic mechanical analysis results indicated that with the increase of bio-based curing agent content,the glass transition temperature of epoxy/bio-based curing agent composites decreased,which was related to the steric effect of diphenylphosphine oxide species that possibly hinder the curing reaction as well as the reduction in the cross-linking density by mono-functional N-H.By the addition of 7.5 wt-%bio-based curing agent,the resulting epoxy composite achieved UL-94 V-0 rating,in addition to limiting oxygen index of 32.0 vol-%.With the increase of content for the bio-based curing agent,the peak of heat release rate and total heat release of the composites gradually decreased.The bio-based curing agent promoted the carbonization of the epoxy matrix,leading to higher char yield with good thermal resistance.The high-quality char layer served as an effective barrier to retard the diffusion of decomposition volatiles and oxygen between molten polymers and the flame.This study provides a renewable strategy for fabricating flame retardant and transparent epoxy thermoset.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFB3802005)the National Natural Science Foundation of China(Grant No.51978002)+1 种基金the Natural Science Foundation for the Higher Education Institutions in Anhui Province of China(Grant No.KJ2020A0845)the Housing and Urban-Rural Construction Science and Technology Plan in Anhui Province of China(Grant No.2021-YF69).
文摘This study focuses on the workability and compressive strength of ceramsite self-compacting concrete with fine aggregate partially substituted by steel slag sand(CSLSCC)to prevent the pollution of steel slag in the environment.The SF,J-ring,visual stability index,and sieve analysis tests are primarily employed in this research to investigate the workability of freshly mixed self-compacting concrete containing steel slag at various steel slag sand replacement rates.The experiment results indicate that CSLSCC with the 20%volume percentage of steel slag(VPS)performs better workability,higher strength,and higher specific strength.The 7-day compressive strength of CSLSCC with the 0.4 of the water-binder ratio(W/B),decreases with the increase of steel slag content,while the 28-day compressive strength increases significantly.The ceramsite self-compacting concrete with good comprehensive performance can be obtained when the substitution rate of steel slag sand for fine aggregate is less than 20%(volume percentage).
基金the National Natural Science Fundation of China(Grant Nos.51978002 and 51403004)the Jiaxing Science and Technology Project(Grant No.2020AD10020)Postdoctoral Science Foundation of China(Grant No.2017M610399).
文摘A phosphine oxide-containing bio-based curing agent was synthesized by addition reaction between furan derivatives and diphenylphosphine oxide.The molecular structure of the as-prepared bio-based curing agent was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy.Dynamic mechanical analysis results indicated that with the increase of bio-based curing agent content,the glass transition temperature of epoxy/bio-based curing agent composites decreased,which was related to the steric effect of diphenylphosphine oxide species that possibly hinder the curing reaction as well as the reduction in the cross-linking density by mono-functional N-H.By the addition of 7.5 wt-%bio-based curing agent,the resulting epoxy composite achieved UL-94 V-0 rating,in addition to limiting oxygen index of 32.0 vol-%.With the increase of content for the bio-based curing agent,the peak of heat release rate and total heat release of the composites gradually decreased.The bio-based curing agent promoted the carbonization of the epoxy matrix,leading to higher char yield with good thermal resistance.The high-quality char layer served as an effective barrier to retard the diffusion of decomposition volatiles and oxygen between molten polymers and the flame.This study provides a renewable strategy for fabricating flame retardant and transparent epoxy thermoset.
