The effect of heavy metals on the properties and hydration of blast furnace slag-cement composites(BFS-CC)remain unclear.In this study,two BFS-CC(denoted as DBFS-CC and WBFS-CC)were prepared by dry and wet grinding of...The effect of heavy metals on the properties and hydration of blast furnace slag-cement composites(BFS-CC)remain unclear.In this study,two BFS-CC(denoted as DBFS-CC and WBFS-CC)were prepared by dry and wet grinding of BFS,respectively.The effect of Cu(II)on BFS-CC’s properties and hydration was investigated by adding representative copper contaminants(CuO,CuCl_(2),and CuS)to the composites.Adding 1.0wt%CuO and 0.5wt%CuS increased the 3-d compressive strength of DBFS-CC by 14.9%and 5.7%,respectively,but suppressed the 3-d strength of WBFS-CC.This trend reversed at 28-d curing,where adding 1.5wt%CuO,2.0wt%CuCl_(2),and 1.5wt%CuS enhanced the compressive strength of WBFS-CC by 23.4%,6.2%,and 13.6%,respectively,but adversely affected the strength of DBFS-CC.For 28-d hydration,adding CuCl_(2)decreased the hydration degree of DBFS-CC but enhanced that of WBFS-CC.Adding CuO promoted the hydration degree of both composites,while adding CuS exhibited inhibitory effects.DBFS-CC immobilized CuCl_(2)better due to a higher hydration degree,while WBFS-CC immobilized CuO and CuS better due to having finer unhydrated BFS particles and a denser matrix.This study not only focuses on the Cu(II)immobilization effect but also reveals the differ-ential effects of Cu(II)species on the hydration process,providing novel insights into heavy metal interactions in BFS-CC systems and their safe disposal.展开更多
The stability of the“surrounding rock-backfill”com posite system is crucial for the safety of mining stopes.This study systematically investigates the effects of steel slag(SS)content and interface angle on the stre...The stability of the“surrounding rock-backfill”com posite system is crucial for the safety of mining stopes.This study systematically investigates the effects of steel slag(SS)content and interface angle on the strength and failure characteristics of rock and SS-cemented paste backfill composite specimens(RBCS)through uniaxial compression strength tests(UCS),acoustic emission systems(AE),and 3 D digital image correlation monitoring technology(3 D-DIC).The intrinsic mechanism by which SS content influences the strength of SS-CPB was revealed through an analysis of its hydration reaction degree and microstructural characteristics under varying SS content.Moreover,a theoretical strength model incorporating different interface angles was developed to explore the impact of interface inclination on failure modes and mechanical strength.The main conclusions are as follows:The incorporation of SS enhances the plastic characteristics of RBCS and reduces its brittleness,with the increase of SS content,the stress-strain curve of RBCS in the“staircase-like”stag e becomes smoother;When the interface angle is 45°,the RBCS stress-strain curve exhibits a bimodal feature,and the failure mode changes from Y-shaped fractures to interface and axial splitting;The addition of SS results in a reduction of hydration products such as Ca(OH)_(2) in the backfill cementing system and an increase in harmful pores,which weakens the bonding performance and strength of RBCS,and the SS content should not exceed 45%;As the interface angle increases,the strength of RBCS decreases,and the critical interface slip angle decreases first and then increases with the increase in the E S/E R ratio.This study provides technical references for the large-scale application of SS in mine backfill.展开更多
基金financially sponsored by the Key R&D Program of Xinjiang Uygur Autonomous Region,China(No.2023B03007-2)the Tianshan Innovation Team,China(No.2023D14013)+9 种基金the Tianchi Hundred-Talent Program,China(No.RSSQ00066865)the Fundamental Research Funds for the Central Universities,China(No.FRF-BD-25-037)the Ganpo Talent Plan,the Taishan Industrial Experts Program,the National Natural Science Foundation of China(Nos.52204414,52204413,and 52204412)the Beijing Natural Science Foundation,China(No.2242046)the National Key R&D Program of China(No.2024YFC3907701)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(No.GZC20230243)the China Postdoctoral Science Foundation(No.2024M750178)the Guangdong Basic and Applied Basic Research Foundation,China(No.2023A1515011609 and 2023A1515110094)the Key Technology Innovation and Advanced Development Program of Chongqing,China(No.CSTB2022TIADKPX0112)the Open Project of State Key Laboratory of Green Building Materials.
文摘The effect of heavy metals on the properties and hydration of blast furnace slag-cement composites(BFS-CC)remain unclear.In this study,two BFS-CC(denoted as DBFS-CC and WBFS-CC)were prepared by dry and wet grinding of BFS,respectively.The effect of Cu(II)on BFS-CC’s properties and hydration was investigated by adding representative copper contaminants(CuO,CuCl_(2),and CuS)to the composites.Adding 1.0wt%CuO and 0.5wt%CuS increased the 3-d compressive strength of DBFS-CC by 14.9%and 5.7%,respectively,but suppressed the 3-d strength of WBFS-CC.This trend reversed at 28-d curing,where adding 1.5wt%CuO,2.0wt%CuCl_(2),and 1.5wt%CuS enhanced the compressive strength of WBFS-CC by 23.4%,6.2%,and 13.6%,respectively,but adversely affected the strength of DBFS-CC.For 28-d hydration,adding CuCl_(2)decreased the hydration degree of DBFS-CC but enhanced that of WBFS-CC.Adding CuO promoted the hydration degree of both composites,while adding CuS exhibited inhibitory effects.DBFS-CC immobilized CuCl_(2)better due to a higher hydration degree,while WBFS-CC immobilized CuO and CuS better due to having finer unhydrated BFS particles and a denser matrix.This study not only focuses on the Cu(II)immobilization effect but also reveals the differ-ential effects of Cu(II)species on the hydration process,providing novel insights into heavy metal interactions in BFS-CC systems and their safe disposal.
基金Project(52308316)supported by the National Natural Science Foundation of China,Project(BBJ2024088)supported by the Fundamental Research Funds for the Central Universities(PhD.Top Innovative Talents Fund of CUMTB),China。
文摘The stability of the“surrounding rock-backfill”com posite system is crucial for the safety of mining stopes.This study systematically investigates the effects of steel slag(SS)content and interface angle on the strength and failure characteristics of rock and SS-cemented paste backfill composite specimens(RBCS)through uniaxial compression strength tests(UCS),acoustic emission systems(AE),and 3 D digital image correlation monitoring technology(3 D-DIC).The intrinsic mechanism by which SS content influences the strength of SS-CPB was revealed through an analysis of its hydration reaction degree and microstructural characteristics under varying SS content.Moreover,a theoretical strength model incorporating different interface angles was developed to explore the impact of interface inclination on failure modes and mechanical strength.The main conclusions are as follows:The incorporation of SS enhances the plastic characteristics of RBCS and reduces its brittleness,with the increase of SS content,the stress-strain curve of RBCS in the“staircase-like”stag e becomes smoother;When the interface angle is 45°,the RBCS stress-strain curve exhibits a bimodal feature,and the failure mode changes from Y-shaped fractures to interface and axial splitting;The addition of SS results in a reduction of hydration products such as Ca(OH)_(2) in the backfill cementing system and an increase in harmful pores,which weakens the bonding performance and strength of RBCS,and the SS content should not exceed 45%;As the interface angle increases,the strength of RBCS decreases,and the critical interface slip angle decreases first and then increases with the increase in the E S/E R ratio.This study provides technical references for the large-scale application of SS in mine backfill.
