A step-by-step load was utilized to mimic the load history of the backfill column in the in-situ curing process.The inner damage of the specimen during curing and uniaxial compressive testing was monitored by electric...A step-by-step load was utilized to mimic the load history of the backfill column in the in-situ curing process.The inner damage of the specimen during curing and uniaxial compressive testing was monitored by electrical resistivity and ultrasonic equipment.Results show that:1)Uniaxial compressive strength(UCS)and elastic modulus(EM)of the samples curing under pressure are higher than those of the control samples without pressure,ranging in ratio from 0.5%to 20.2%and 7.1%to 52.3%,respectively,and are influenced by the initial loading age(ILA)and stress strength ratio(SSR).The SSR during curing should not exceed 80%.2)The earlier the ILA is,the higher the total strain becomes.The higher the SSR applies,the larger the total strain gets.The creep strain increases with the increase of SSR and can be described by Burger’s viscoelastic creep model.When SSR is less than 80%,the earlier the ILA is,the smaller the creep strain becomes after the last step-loading.3)The stability of the early age backfill column under pressure can be monitored based on the change of ultrasonic pulse velocity(UPV)and electrical resistivity.展开更多
We experimentally investigated the effect of curing conditions on the durability of UHPC under flexuralload.Moreover,the mechanisms of the effect of curing conditions were revealed from the microstructuralpoint of vie...We experimentally investigated the effect of curing conditions on the durability of UHPC under flexuralload.Moreover,the mechanisms of the effect of curing conditions were revealed from the microstructuralpoint of view with environmentalscanning electron microscopy（ESEM）and X-ray computerized tomography（X-ray CT）.The experimentalresults show that the flexuralload has negative influence on the durability of UHPC,but UHPC stillexhibits excellent durability under flexuralload.Besides,the curing conditions do show influences on the durability of UHPC.Compared with standard and steam curing,oven curing led to a lower chloride resistance and freeze-thaw performance of UHPC.The microstructure of UHPC paste was detected with ESEM.It is revealed that,compared with standard and steam cured UHPC,the lower reaction degree and internalmicrocracks are the causes for the lower chloride resistance of oven cured UHPC.The defects distribution in UHPC before and after freeze-thaw action was investigated with X-ray CT.The number of defects in oven cured UHPC increases the fastest during the freeze-thaw action due to its more defective microstructure展开更多
基金Project(51974192)supported by the National Natural Science Foundation of ChinaProject(201803D31044)supported by the Program for Key Research Project of Shanxi Province in the Field of Social Development,ChinaProject(201801D121092)supported by the Applied Basic Research Project of Shanxi Province,China。
文摘A step-by-step load was utilized to mimic the load history of the backfill column in the in-situ curing process.The inner damage of the specimen during curing and uniaxial compressive testing was monitored by electrical resistivity and ultrasonic equipment.Results show that:1)Uniaxial compressive strength(UCS)and elastic modulus(EM)of the samples curing under pressure are higher than those of the control samples without pressure,ranging in ratio from 0.5%to 20.2%and 7.1%to 52.3%,respectively,and are influenced by the initial loading age(ILA)and stress strength ratio(SSR).The SSR during curing should not exceed 80%.2)The earlier the ILA is,the higher the total strain becomes.The higher the SSR applies,the larger the total strain gets.The creep strain increases with the increase of SSR and can be described by Burger’s viscoelastic creep model.When SSR is less than 80%,the earlier the ILA is,the smaller the creep strain becomes after the last step-loading.3)The stability of the early age backfill column under pressure can be monitored based on the change of ultrasonic pulse velocity(UPV)and electrical resistivity.
基金Funded by the National Natural Science Foundation of China(No.51378113)the Fundamental Research Funds for the Central Universities(No.3212002206)
文摘We experimentally investigated the effect of curing conditions on the durability of UHPC under flexuralload.Moreover,the mechanisms of the effect of curing conditions were revealed from the microstructuralpoint of view with environmentalscanning electron microscopy（ESEM）and X-ray computerized tomography（X-ray CT）.The experimentalresults show that the flexuralload has negative influence on the durability of UHPC,but UHPC stillexhibits excellent durability under flexuralload.Besides,the curing conditions do show influences on the durability of UHPC.Compared with standard and steam curing,oven curing led to a lower chloride resistance and freeze-thaw performance of UHPC.The microstructure of UHPC paste was detected with ESEM.It is revealed that,compared with standard and steam cured UHPC,the lower reaction degree and internalmicrocracks are the causes for the lower chloride resistance of oven cured UHPC.The defects distribution in UHPC before and after freeze-thaw action was investigated with X-ray CT.The number of defects in oven cured UHPC increases the fastest during the freeze-thaw action due to its more defective microstructure
