纤维增韧水泥基复合材料的弯曲性能试验研究

Study on the bending capacity of cementitious composites reinforced with fibers

对多种配合比的纤维增韧水泥基复合材料(ECC)进行了薄板四点弯曲试验,并对试验所测得的荷载-挠度曲线进行了弯曲性能指数的计算,定量分析了各种因素对于材料弯曲性能的影响,结果表明:粉煤灰比率(FA/C)的增加将提高材料的弯曲性能,但会降低其抗弯强度,其含量宜在0.45～0.55;水胶比(W/B)对弯曲性能影响较为敏感,W/B≤0.36时,增加水胶比将有效提高材料弯曲能力,W/B>0.36时,水胶比的增加将导致材料弯曲能力的骤降,合适的W/B宜在0.26～0.36;适量地增加砂胶比和矿渣含量有益于材料弯曲性能的提高,过量矿渣将产生负面影响。此外,纤维的种类及其体积含量也是材料弯曲性能的重要影响因素,材料发生位移硬化的临界PVA纤维体积含量为1%。

Four-points bending tests had been taken to test the bending capacity of various kinds of engineering cementitious composites （ECC）.Based on calculated bending capacity indices deriving from realationship curves between load and midspan deflection, analysed impacts of various factors on the bending capacity of ECC.Results showed：increasing fly ash content is advantegerous to ECC＇s bending capacity,but its bending strength decreases conversely, the proper fly ash to binder ratio should be between 0.45 and 0.55 ;while water-binder ratio is sensitive to ECC＇s flexibility, as it is below 0.36, increasing the water-binder ratio is effective for the advance of ECC＇s flexibility, when beyond 0.36, increas- ing water-binder ratio causes ECC＇s flexibility to decrease dramatically, consequently,the proper water-binder ratio should be between 0.26 and 0.36.Moreover,increasing the sand-binder ratio and the content of slag properly benefits for composites＇ flexibility,however, excessive amount of slag will surely decrease the flexibility of ECC.Bcsides, sorts of fibers and the volume content are also important ingredients which impact greatly on ECC＇s flexibility.The critical volume content of PVA fibers to insure ECC to have the load-deflection harden character is l%.This research will provide a reference for deeply researching on mechanical properties of the ECC.