CHARACTERIZATION OF FIBER-REINFORCED CEMENT COMPOSITES BY THEIR TENSILE STRESS-STRAIN BEHAVIOR AND QUANTIFICATION OF CRACK FORMATION

摘要

The behavior of fiber reinforced cement composites (FRCC) can be described and quantified by a variety of parameters, such as strength and strain capacity, toughness index, and fracture energy, obtained from tests in tension or bending in a large number different configurations including varying specimen geometries and test setups. Depending on the details of the individual testing procedures, a particular composite may be characterized and classified inconsistently. To enable the evaluation of FRCC performance, a common basis for comparison is required, which will reflect the relevant material characteristics. Standardized test methods have been established for conventional FRCC with tension softening behavior. These test methods provide parameters, which are difficult to implement in structural design and cannot be universally applied to High Performance FRCC with strain hardening and multiple cracking behavior in tension. In this paper, a tensile test and analysis procedure is conceptually outlined to characterize HPFRCC by their tensile stress-strain relationship and quantification of cracking. The deformation characteristics of the composite, i.e. the crack formation including number, position, width, and spacing, are monitored and quantified by a digital image analysis process. Based on these material properties, the level of mechanical performance of HPFRCC can be evaluated and compared.