钢纤维混凝土的损伤自感知试验研究

Experimental study on self-sensing damage of steel fiber reinforced concrete

试验将短钢纤维加入混凝土中用以改善其导电性能、抗弯性能、韧性和抗裂能力。利用四电极法研究了加入不同短钢纤维掺量的水泥基复合材料的损伤自感知能力。分析讨论了四电极法相较于二电极法在电学参数测量中的优势,并以测量中出现的欧姆极化现象对四电极法的电极分布做出建议。通过试验分析,分别建立了不同短钢纤维掺量的混凝土梁的养护时间与电阻率、受荷状态下电阻变化率与挠度和电阻变化率与裂缝宽度之间的关系。研究表明:短钢纤维的掺量增加,能够增强混凝土梁的导电性能、抗弯强度、韧性和抗裂能力。且短钢纤维的掺入能加速形成混凝土的导电网络。养护7d时,混凝土梁已具有一定的损伤自感知能力。当钢纤维掺量为60kg/m3时,混凝土的机敏性最佳。

In this experiment,steel fiber is added into concrete to improve its electrical conductivity,flexural performance,toughness and crack resistance.The damage self-sensing ability of cement-based composites with different short steel fiber content was studied by four-electrode method.The advantages of the four-electrode method compared with the two-electrode method in the measurement of electrical parameters are discussed,and some suggestions on the electrode distribution of the four-electrode method are made,according to the ohmic polarization phenomenon in the measurement.The relationship between curing time and resistivity of concrete beams with different steel fiber content,the change rate of resistance and deflection,and the change rate of resistance and crack width under load are established by experiments.The results show that the conductivity,flexural strength,toughness and crack resistance of concrete beams can be enhanced with the increase of short steel fiber content.And the addition of short steel fiber can accelerate the formation of conductive network of concrete.After 7 days of maintenance,concrete beams have a certain self-sensing ability of damage.When the steel fiber content is 60kg/m3,the agility of concrete is the best.