矿渣与粉煤灰掺量对高延性水泥基复合材料力学性能与应变硬化特性的影响

Effects of Dosage of Slag and Fly Ash on Mechanical Properties and Strain-hardening Characteristics of High-ductility Cementitous Composites(HDCC)

高延性水泥基复合材料(High Ductility Cementitious Composites,HDCC)是指在弯曲和拉伸荷载作用下具有应变硬化特性的水泥基复合材料,具有单轴拉伸延性好,耐久性能优异等优点。在材料设计中用大掺量的粉煤灰来替代水泥,以实现更加优异的高延性。本文研究了在聚乙烯醇(polyvinyl alcohol,PVA)纤维体积掺量为1.2%和1.4%时,同时掺入高炉矿渣与粉煤灰制备高延性水泥基复合材料,通过改变高炉矿渣与粉煤灰的掺量,得到试件的抗压强度、抗折强度与弯曲韧性,用以对比矿渣与粉煤灰不同质量比例对高延性水泥基复合材料力学性能、弯曲韧性和表面裂纹特征的影响规律。结果显示,当矿渣和粉煤灰掺量分别为总胶凝材料质量的40%和10%时,试件呈现出良好的应变硬化与多缝开裂特性,最大挠度达到10.79mm,极限拉应变为1.26%,裂纹数量达到14条。表明了矿渣的掺入有利于在保证高延性水泥基复合材料具有应变硬化特性的前提下,可以有效提高高延性水泥基复合材料中的强度和弯曲韧性,对于此类材料的工程应用十分有益。

High-ductility cementitious composites （HDCC） refers to the cementitious composites with strain hardening properties under bending and tension loading, which has good uniaxial tensile ductility, excellent durability, etc. High content of fly ash is used to replace the cement in order to achieve more excellent ductility. In this study, the volume content of PVA fiber was 1.2% and 1.4%, the blast furnace slag and fly ash added into HDCC. By changing the blast furnace slag and fly ash content, the compressive strength, flexural strength and flexural toughness of specimen obtained to reveal the influence of different mass ratio of slag and fly ash on the mechanical properties, toughness and surface crack characteristics of HDCC. The results showed that when the slag and fly ash were 40% and 10% of the total mass of cementitious materials, the specimen showed a good strain hardening and multiple cracking characteristics, maximum deflection reached 10.79mm, tensile strain capacity of 1.26% and the number of cracks was 14. The incorporation of slag was beneficial to ensure the high ductility of HDCC and effectively improved the strength and flexural toughness of HDCC, which was very useful for engineering applications of these materials.