低模量早强型高延性混凝土的力学行为

Mechanical Performance of Engineered Cementitious Composites(ECC) with Low Modulus and Early Strength

摘要:

基于路面工程中超薄白色罩面的应用背景,研发了1种低模量早强型高延性混凝土（LMESECC）,并通过试验研究了LMESECC在不同龄期时的抗压、单轴拉伸和四点弯曲行为,测量了其干燥收缩值,讨论了其早期开裂潜能与约束收缩开裂行为.结果表明：3d龄期时,LMESECC的抗压强度和弯曲强度分别达到31MPa和7MPa,满足开放交通的需求;在受拉伸和弯曲作用时,LMESECC表现出较大的变形能力,且表现出多缝开裂现象,裂缝宽度可控制在60μm以下,其弹性模量约为14GPa,远小于普通混凝土;尽管LMESECC的干燥收缩值大于普通混凝土,但是在约束条件下表现出极好的抗开裂能力.LMESECC所表现出来的材料特性可大大延长混凝土路面超薄罩面的使用寿命.

Abstract:

Based on the application background of ultra thin white topping overlay in pavement engineering, the mechanical properties of low modulus and early strength engineered cementitious composites(LMES ECC) including compressive, tensile, and flexural behaviors were investigated. In addition, the drying shrinkage of LMES ECC and its cracking potential at early age was also discussed. The experimental results show that the 3 d compressive strength and 3 d flexural strength of LMES ECC reach 31MPa and 7MPa, respectively, which satisfies the requirements of traffic opening. Under tensile and flexural loadings, LMES ECC exhibits remarkable deformation capacity along with multiple micro cracks development, meanwhile the crack width is controlled below 60μm. The elastic modulus of LMES ECC is around 14 GPa which is much lower than that of normal concrete. Under the restrained condition, LMES ECC shows very excellent crack resistant ability, although it has higher drying shrinkage value. The typical material characteristic of LMES ECC is expected to make great improvement of the service life of the ultra thin white topping overlay in pavement engineering.