钢纤维对高强混凝土弯曲性能影响的试验研究

Influence of Steel Fiber on Flexural Property of High Strength Concrete

选用工程中常用的铣削型、切断弓型、剪切波纹型钢纤维,以不超过2.0%的体积分数掺入高强混凝土中,通过2种尺寸小梁试件的弯曲强度和韧性试验,研究了钢纤维类型及掺量对高强混凝土弯曲强度及变形性能的影响.结果表明:当3种类型钢纤维分别以2.0%的体积分数掺入高强混凝土中时,可使高强混凝土抗裂能力分别提高72%,41%和42%,弯曲极限强度分别提高90%,84%和57%.钢纤维对高强混凝土试件的尺寸效应系数影响显著,试验时应考虑试件尺寸对试验结果的影响.钢纤维高强混凝土弯曲韧度指数及承载力变化系数均随钢纤维体积分数的增大而增大,并大于理想弹塑性材料的相应值.不同类型钢纤维对高强混凝土弯曲强度及弯曲韧性的改善效果不同,可通过改进钢纤维的加工工艺、表面形状等来提高钢纤维对高强混凝土的增强增韧效果.

Milled steel fiber（MF）,bended steel fiber（BF） and sheared steel fiber（SF） were mixed in high strength concrete at the volume fraction below 2.0%.By means of flexural strength test and flexural toughness test of two kinds of beam specimens,the influences of type and volume fraction of steel fibers on the strength and deformation of high strength concrete were investigated.The results show that when the three kinds of steel fibers are mixed into high strength concrete at the volume fraction of 2.0%,the cracking resistance of high strength concrete can be improved by 72%,41% and 42%,and ultimate flexural strength can be improved by 90%,84% and 57% respectively.Steel fiber has a distinct influence on size effect of high strength concrete,which must be taken into account when carrying out experiments.Flexural toughness index and variation factor of flexural resistance are improved with the increase of volume fraction of steel fiber and they are higher than that of ideal elastic plastic material.Different steel fiber has a different effects on flexural performance of high strength concrete,and the strengthening and toughening effect on high strength concrete can be achieved by improving the processing technique,macroshape of steel fiber.