离心成型钢纤维混凝土劈裂抗拉强度试验研究

通过试验研究了离心工艺参数、骨料级配、钢纤维长度和体积率等因素对离心成型钢纤维混凝土环形截面构件的轴向和环向劈裂抗拉强度的影响规律.结果表明：增大离心加速度有利于提高钢纤维混凝土的轴向劈裂抗拉强度;选用长度较小的钢纤维时,适当延长中速阶段的离心时间也可提高钢纤维混凝土的轴向劈裂抗拉强度;选用长度较大的钢纤维时,适当延长中速阶段的离心时间或增大离心加速度可提高钢纤维混凝土的环向劈裂抗拉强度.选取粗骨料级配5—10mm可获得较高的轴向劈裂抗拉强度,选取粗骨料级配5—15mm可获得较高的环向劈裂抗拉强度.对于外径为550mm以内的离心成型环形截面构件,钢纤维长度宜为25—32mm,体积率不宜大于1.2%.经统计分析提出了离心成型钢纤维混凝土的劈裂抗拉强度计算公式.

Experimental Study on Splitting-tensile Strength of Centrifugal Shaping SFRC

A series of experiments were conducted to study the axial and circumferential splitting-tensile strength of centrifugal shaping steel fiber reinforced concrete (SFRC) members of circular section, in which considered the coefficients of centrifugation, the grades of coarse aggregate, the length and volume fraction of steel fiber. The results show that the axial splitting-tensile strength increases with increase of centrifugal acceleration in middle-speed stage, it also increases by properly elongating centrifugal time in middle-speed stage while the steel fiber length is shorter. The circumferential splitting-tensile strength increases by properly elongating centrifugal time or raising centrifugal acceleration in middle-speed stage when longer steel fiber is used. The higher axial splitting-tensile strength can be obtained by selecting the grade 5-10mm of coarse aggregate, the higher circumferential splitting-tensile strength can be obtained by selecting the grade 5-15mm of coarse aggregate. The steel fiber length is better in range of 25-32mm, the volume fraction of steel fiber is better no more than 1.2% for the centrifugal shaping SFRC members within 550mm outer diameter. The formula is proposed for calculating the splitting-tensile strength of spun-cast SFRC by statistical analysis of the test data.