高强砼与钢纤维高强砼冲击和疲劳特性及其机理的研究

STUDY ON THE IMPACT AND FATIGUE PERFORMANCE AND MECHANISM OF HIGH STRENGTH CONCRETE AND STEEL FIBER REINFORCED HIGH STRENGTH CONCRETE

本文主要采用了颗粒型与纤维型材料双重复合技术,配置了四个系列的高强和钢纤维高强混凝土.研究了在重复荷载作用下,它们的冲击、疲劳特性及其抑制损伤的机理.实验结果充分表明,因颗粒型材料硅灰的掺入,调整与改善了集料-基体、纤维-基体间界面区和整体的性状与结构,减少与缩小了裂缝源的数目、尺度,消除了界面区的薄弱,使界面粘结强度提高、界面效应范围增大,集料-基体和纤维-基体双重空间叠加效应增强,从而提高了抗冲击与耐疲劳能力;因钢纤维的掺入,在高强砼结构形成与破坏过程中,有效地抑制了裂缝的引发与扩展,缓和了裂缝尖端应力集中程度,推迟了冲击和疲劳损伤过程,使用寿命明显提高;当钢纤维与硅灰复合掺入高强砼中,两种材料各施其长、相互促进,产生优异的双重复合效应,更大幅度地提高了高强砼抗冲击与耐疲劳能力.

In this paper,four series of high strength concrete and steel fiber reinforced high strength concrete are developed by using the double composite technology of particulate and fibrous materials.Their impact and fatigue performance and the mechanism of resisting damage under repeated load are investigated.Experimental results fully indicate that the characteristic and structure of both inter-facial zone between aggregate-matrix and fiber-matrix as well as that of the entirety of such concrete are adjusted and improved because of the addition of particulate material(silica fume).Also, the addition of silica fume reduces the amount of original crack, lessens its size, eliminates the interfacial weakness, increases the interfacial bond strength, widens the effective range of interface, enhances the double spacial superimposing effect of aggregate-matrix and fiber-matrix, and thus heighens the capacity of resisting impact and fatigue. It effectively restrains the initiation and propagation of crack in the course of forming and failing of high strength concrete structure, mitigates the stress concentration extent in the tip of crack, delayes the damage process caused by impact and fatigue as well as promotes the service life obviously,, when steel fiber anb silica fume are added into high strength concrete simultaneously(i.e.to add the composite of steel fiber and silica fume), they will make full use of their advantages, and make up each other's shortcomings, and produce an excellent doub'le composits effect.As a result, the ability of resisting impact and fatigue will be remarkably raised.