This study aims to reveal the mechanism that how the content of steel fibers and strength grades affect the macro performance of the ultra-high performance fiber reinforced cementitious composite （UHPFRCC） and to st...This study aims to reveal the mechanism that how the content of steel fibers and strength grades affect the macro performance of the ultra-high performance fiber reinforced cementitious composite （UHPFRCC） and to study the UHPFRCC durability under the combined effect of loads and environments. Three types of high and ultra-high performance fiber reinforced cement composites with different strength grades （100, 150, 200 MPa） and different steel fiber volume fractions （0%, 1%, 2%, 3%） are prepared. The main properties of mechanical performance and short-term durability are studied. A preloading frame is designed to apply a four- point load external flexural stress with a stress selection ratio of 0.5 for UHPFRCC150 specimens. The results show that the growth in strength grade with a proper content of steel fiber greatly increases the strength and toughness of the HPFRCC and the UHPFRCC while decreasing the dry-shrinkage ratio. For the loaded specimens, the existence of steel fiber can reduce the negative influence of tensile stress on the Cl- penetration resistance of the UHPFRCC in addition to improving its ability to resist the freeze-thaw damage.展开更多
Ultra-high performance cementitious composites (UHPCC) were prepared by replacing 60% of cement with ultra-fine industrial waste powders.The dynamic damage and compressive stress-strain relations of UHPCC were studied...Ultra-high performance cementitious composites (UHPCC) were prepared by replacing 60% of cement with ultra-fine industrial waste powders.The dynamic damage and compressive stress-strain relations of UHPCC were studied using split Hopkinson pressure bar (SHPB).The damage of UHPCC subjected to repeated impact was measured by the ultrasonic pulse velocity method.Results show that the dynamic damage of UHPCC increases linearly with impact times and the abilities of repeated impact resistance of UHPCC are improved with increasing fiber volume fraction.The stress waves on impact were recorded and the average stress,strain and strain rate of UHPCC were calculated based on the wave propagation theory.The effects of strain rate,fibers volume fraction and impact times on the stress-strain relations of UHPCC were studied.Results show that the peak stress and elastic modulus decrease while the strain rate and peak strain increase gradually with increasing impact times.展开更多
基金The Technical Research Program from NV Bekaert SA of Belgium (No. 8612000003)the National Natural Science Foundation of China (No. 50908047)
文摘This study aims to reveal the mechanism that how the content of steel fibers and strength grades affect the macro performance of the ultra-high performance fiber reinforced cementitious composite （UHPFRCC） and to study the UHPFRCC durability under the combined effect of loads and environments. Three types of high and ultra-high performance fiber reinforced cement composites with different strength grades （100, 150, 200 MPa） and different steel fiber volume fractions （0%, 1%, 2%, 3%） are prepared. The main properties of mechanical performance and short-term durability are studied. A preloading frame is designed to apply a four- point load external flexural stress with a stress selection ratio of 0.5 for UHPFRCC150 specimens. The results show that the growth in strength grade with a proper content of steel fiber greatly increases the strength and toughness of the HPFRCC and the UHPFRCC while decreasing the dry-shrinkage ratio. For the loaded specimens, the existence of steel fiber can reduce the negative influence of tensile stress on the Cl- penetration resistance of the UHPFRCC in addition to improving its ability to resist the freeze-thaw damage.
基金supported by the National Natural Science Foundation of China (Grant No.50808101)Jiangsu Provincial Program for Basic Research (Natural Science Foundation) (Grant No.BK2008417)+1 种基金China Postdoctoral Science Foundation (Grant No.20080431100)Excellence Plan "Zijin Star" of NJUST
文摘Ultra-high performance cementitious composites (UHPCC) were prepared by replacing 60% of cement with ultra-fine industrial waste powders.The dynamic damage and compressive stress-strain relations of UHPCC were studied using split Hopkinson pressure bar (SHPB).The damage of UHPCC subjected to repeated impact was measured by the ultrasonic pulse velocity method.Results show that the dynamic damage of UHPCC increases linearly with impact times and the abilities of repeated impact resistance of UHPCC are improved with increasing fiber volume fraction.The stress waves on impact were recorded and the average stress,strain and strain rate of UHPCC were calculated based on the wave propagation theory.The effects of strain rate,fibers volume fraction and impact times on the stress-strain relations of UHPCC were studied.Results show that the peak stress and elastic modulus decrease while the strain rate and peak strain increase gradually with increasing impact times.
