砂浆流变性能和外界磁场强度对钢纤维分布特征的影响

Effects of Rheological Properties of Mortar and Magnetic Field Strength on Steel Fiber Distribution Characteristics

通过改变减水剂掺量来调整砂浆屈服应力和塑性粘度,分析了屈服应力、塑性粘度和外界磁场强度对钢纤维分散性和方向性的影响。结果表明:当屈服应力小于16.5 Pa时,钢纤维在浆体流动剪切和自身重力作用下可以克服屈服应力沿流动方向旋转定向,随着流动距离增大,方向系数逐渐增大,但当流动距离大于0.4 m后,方向系数趋于稳定;当屈服应力小于2.5 Pa、塑性粘度小于10 Pa·s时,钢纤维发生沉降。此外,提高外界磁场强度可以使钢纤维方向系数明显增大,减水剂掺量一定时,与不加磁场相比,通过6.39 mT磁场的水泥砂浆钢纤维方向系数可增大18%~40%。

To adjust the yield stress and plastic viscosity of mortar,the amount of superplasticizer was changed.Effects of yield stress,plastic viscosity and magnetic field strength on the dispersion and directivity of steel fibers were analyzed.The results showed that when the yield stress was less than 16.5 Pa,steel fiber could overcome the yield stress and rotate and orient along the flow direction under the action of mortar flow shear and self-gravity.With the increase of flow distance,orientation coefficient gradually increased,but when the flow distance was greater than 0.4 m,orientation coefficient tended to be stable.When yield stress was less than 2.5 Pa and plastic viscosity was less than 10 Pa·s,the steel fiber would settle.In addition,increasing the intensity of the external magnetic field could significantly improve orientation coefficient of steel fiber.When the content of the superplasticizer was certain,orientation coefficient of steel fiber of cement mortar passing through a 6.39 mT magnetic field was increased by 18%—40%compared with that without a magnetic field.