高性能PVA纤维增强水泥基材料的制备与性能

Preparation and Properties of High Performance PVA Fiber Reinforced Cementitious Materials

为了获得高性能PVA纤维增强水泥基复合材料的制备方法,研究了砂的颗粒级配、水胶比和粉煤灰掺量对高延性纤维增强水泥基复合材料(Engineered Cementitious Composites,ECC)的弯曲性能、抗压、抗折强度及开裂模式的影响。结果表明:随着砂的细度模数降低,ECC的跨中挠度增大,早期强度提高,但后期强度变化不明显。随着水胶比的增大,ECC的初始开裂荷载降低,跨中挠度增大,平均裂缝宽度增加。0.25水胶比的ECC的抗压强度可以满足高强度等级的要求。0.35水胶比的抗压强度可以满足对普通强度等级的要求。随着粉煤灰掺量的增加,ECC的初始开裂荷载降低、抗折和抗压强度逐渐降低,ECC的跨中挠度提高,平均裂缝宽度变小。在水胶比一定的条件下,采用细砂,适当增加粉煤灰掺量有助于提高ECC的韧性和延性。

In order to obtain the preparation method of high performance PVA fiber reinforced cementitious material（also called Engineered Cementitious Composites,ECC）,the effects of gradation of sand,water-binder ratio（W/B） and content of fly ash on the bending properties,compressive strength,flexural strength and cracking pattern of ECC were investigated in this paper.The results showed that with the fineness modulus of sand decreased,ECC＇s mid-span deflection increased,the early strength increased but the strength in the long term did not change significantly.As the water-binder ratio of ECC increased,the initial cracking load of ECC lowered,deflection at mid-span and the average crack width increased.The compressive strength of ECC with W/B of 0.25 could meet the requirements of high-strength concrete grades.The compressive strength of ECC with W/B of 0.35 could meet the requirements of ordinary strength concrete grades.With the fly ash content of ECC increased,the initial cracking load of ECC lowered,the flexural and compressive strength gradually decreased,the deflection of ECC enhanced,as well as the average crack width became smaller.As the W/B of ECC is fixed,using finer sand and increasing fly ash content appropriately will help to further improve the toughness and ductility of ECC.