New Micromechanics Design Theory for Pseudostrain Hardening Cementitious Composite

Abstract

The micromechanics design theory has realized random short fiber-reinforced cement composites showing pseudostrain hardening (PSH) behavior with over 5% of strain capacity under tension. Nevertheless, this existing theory currently is limited to specific constituent properties, which does not account for chemical bond and fiber rupture. This article presents a new design theory that eliminates this restriction, achieving fiber rupture type PSH-random short fiber-reinforced cement composites with high-performance hydrophilic fibers like polyvinyl alcohol fibers. Uniaxial tensile tests are conducted employing polyvinyl alcohol fiber composites, the results of which support the validity of the proposed theory. Furthermore, parametric study employing the proposed theory quantitatively evaluates the effects of composite's micromechanics parameters, such as bond strength and fiber strength, on composite performance. This parametric study reveals that continuously increasing the degree of fiber rupture (fiber rupture intensity) enhances the strength performance of composites but not energy performance. However, an optimum rupture intensity exists for maximizing energy performance, which is critical for PSH behavior. The consistency between theoretical predictions and experimental results consequently demonstrates that the proposed theory can be utilized practically as a powerful and comprehensive tool for PSH composite design.

Mechanisms of Multiple Cracking and Fracture of DFRCC under Fatigue Flexure

“…For example, the process of multiple cracking and the fracture mechanism have not been investigated under fatigue loading, although there have been several studies under static loading (Li et al 1992;Kanda et al 1999;Maalej et al 1994). Therefore, they need to be clarified to obtain the principles for material design as well as structural application.…”

Full Scale Processing Investigation for ECC Pre-cast Structural Element

“…Fresh properties and compressive tests were based on the standard method specified in JIS while uniaxial tensile tests were based on two methods tentatively The two tensile tests have distinct features. In the TC tensile test 5) , a plate shaped specimen is directly supported by pneumatic chucks and subjected to tensile loads with hinge or fixed boundary conditions as shown in Fig.1. This method is easy to execute, can deal with a number of specimens in a limited time and has large accumulation of past records.…”

A review on durability properties of strain hardening fibre reinforced cementitious composites (SHFRCC)

“…An important feature of SHFRCC composites exhibiting strain hardening and multiple cracking behaviour is the increase of postcracking strength beyond first crack strength accompanied by the development of closely spaced multiple cracks. SHFRCC containing mono fibres [2][3][4][5] and hybrid fibres have also been developed [6][7][8][9]. SHFRCC exhibits superior crack width and spacing control in the pseudo strain-hardening phase, as depicted in Fig.…”

“…2. Superior tensile strain hardening response of ECC can be engineered by tailoring the composite ingredients with the aid of micromechanically based formulations [5,7,[10][11][12]. This paper reviews and presents some of the most important durability properties of the SHFRCC materials, such as crack width control, permeability in cracked state, corrosion resistance, freeze-thaw resistance, performance in hot environments, shrinkage cracking resistance, and combined mechanical and environmental loads.…”

“…ECC is ultra ductile cement based composites reinforced with short random fibres (metallic and/or nonmetallic) which exhibit strainhardening and multiple-cracking behaviors in uni-axial tension as well as in bending [2-5, 7-8, [10][11][12]. It is a strain hardening type of fibre reinforced cementitious composite that is microstructurally tailored based on micromechanics [3][4][5][10][11][12]. ECC typically has tensile strain capacity of more than 3%, with spacing between multiple cracks at saturation less than 3 mm and maximum crack width less than 100 micrometers.…”