邓宗才+王辉+刘岩

摘要：為掌握生态钢纤维混凝土的弯曲韧性和断裂性能，分别对掺率（体积分数）为1.0%，1.7%，2.4%的2种异形生态钢纤维混凝土和掺率为0.7%，1.3%的原生高强钢纤维增强混凝土进行了无切口梁四点弯曲韧性试验和切口梁三点弯曲断裂试验。研究结果表明：生态钢纤维掺率为1.0%时，无切口梁四点弯曲荷载-挠度曲线和切口梁三点弯曲荷载-挠度及荷载-切口张开位移曲线在达到峰值后都出现局部陡降，试件残余强度较小，断裂韧度值较低，纤维对改善混凝土弯曲韧性和断裂性能的作用较小；当生态钢纤维掺率为1.7%时，混凝土弯曲韧性和断裂性能均得到显著提高，混凝土在变形达到15δult，p（δult，p为素混凝土峰值荷载对应的挠度）或70Dult，p（Dult，p为素混凝土峰值荷载对应的切口张开位移）水平时，依然具有较高的持荷能力和较好的韧性，波浪型生态钢纤维混凝土断裂能和断裂韧度是素混凝土的27.59倍和8.35倍；生态钢纤维掺率为2.4%时，混凝土弯曲韧性指标、断裂能和断裂韧度进一步增加；掺率为1.7%的生态钢纤维混凝土增韧和抗断裂效果与掺率为0.7%的原生高强钢纤维混凝土相当。

关键词：生态钢纤维混凝土；原生高强钢纤维混凝土；弯曲韧性；断裂性能；掺率

中图分类号：TU502 文献标志码：A

文章编号：1673-2049（2017）02-0111-08

Abstract：In order to grasp the flexural toughness and fracture property of ecological steel fiber reinforced concrete， four-point bending toughness test for beam and three-point bending fracture test for notched beam were carried out with different volume fractions of ecological steel fibers 1.0%， 1.7%，2.4% and different volume fractions of native high strength steel fibers 0.7%， 1.3%. The results show that when the volume fraction of ecological steel fiber is 1.0%， four-point bending load-deflection curves of beam and three-point bending load-deflection curves and load-crack mouth opening displacement curves of notched beam are partial steep drop after the peak point， residual strength and fracture toughness are low.Ecological steel fibers have less improvement on toughness and fracture properties. When the volume fraction of ecological steel fiber is 1.7%， the flexural toughness and fracture property of concrete are greatly improved，concretes still have high toughness when the deformation is 15δult，p（δult，p is deflection corresponding to peak load of plain concrete） and 70Dult，p（Dult，p is peak crack mouth opening displacement corresponding to peak load of plain concrete）， fracture energy and fracture toughness of wavy ecological steel fiber concrete are 27.59 times and 8.35 times to plain concrete. When the volume fraction of ecological steel fiber is 2.4%， flexural toughness index， fracture energy and fracture toughness further increase. The toughening and fracture resistance effects of 1.7% volume fraction of ecological steel fiber are almost close to those of 0.7% native high strength steel fiber.

Key words：ecological steel fiber reinforced concrete； native high strength steel fiber reinforced concrete； flexural toughness； fracture toughness； volume fraction