http://hdl.handle.net/2027.42/63588 2013-05-24T21:47:14Z http://hdl.handle.net/2027.42/94214 Rheology, fiber dispersion, and robust properties of Engineered Cementitious Composites Li, Mo; Li, Victor C. The capability of processing robust Engineered Cementitious Composites (ECC) materials with consistent mechanical properties is crucial for gaining acceptance of this new construction material in various structural applications. ECC's tensile strain-hardening behavior and magnitude of tensile strain capacity are closely associated with fiber dispersion uniformity, which determines the fiber bridging strength, complementary energy, critical flaw size and degree of multiple-crack saturation. This study investigates the correlation between the rheological parameters of ECC mortar before adding PVA fibers, dispersion of PVA fibers, and ECC composite tensile properties. The correlation between Marsh cone flow rate and plastic viscosity was established for ECC mortar, justifying the use of the Marsh cone as a simple rheology measurement and control method before fibers are added. An optimal range of Marsh cone flow rate was found that led to improved fiber dispersion uniformity and more consistent tensile strain capacity in the composite. When coupled with the micromechanics based ingredient-tailoring methodology, this rheological control approach serves as an effective ECC fresh property design guide for achieving robust ECC composite hardening properties. 2012-07-25T00:00:00Z http://hdl.handle.net/2027.42/94213 Tailoring ECC for Special Attributes: A Review Li, Victor C. This article reviews the tailoring of engineered cementitious composites (ECC), a type of high performance fiber reinforced cementitious composites with a theoretical design basis, for special attributes or functions. The design basis, a set of analytic tools built on micromechanics, provides guidelines for tailoring of fiber, matrix, and fiber/matrix interfaces to attain tensile ductility in ECC. If conditions for controlled multiple cracking are disturbed by the need to introduce ingredients to attain a special attribute or function, micromechanics then serve as a systematic and rational means to efficiently recover composite tensile ductility. Three examples of ECCs with attributes of lightweight, high early strength, and self-healing functions, are used to illustrate these tailoring concepts. The fundamental approach, however, is broadly applicable to a wide variety of ECCs designed for targeted fresh and/or hardened characteristics required for specific applications. 2012-09-18T00:00:00Z http://hdl.handle.net/2027.42/94212 Can Concrete be Bendable? Li, Victor C. 2012-01-01T00:00:00Z http://hdl.handle.net/2027.42/94211 Strain hardening fiber reinforced alkali-activated mortar – A feasibility study Lee, Bang Yeon; Cho, Chang-Geun; Lim, Hyun-Jin; Song, Jin-Kyu; Yang, Keun-Hyeok; Li, Victor C. The development of cementless slag-based alkali-activated mortar has previously been demonstrated. While greener than Portland cement based compositions, slag-based alkali-activated mortar tends to be highly brittle. In the present work, the feasibility of developing a new strain-hardening fiber reinforced composite using slag-based alkali-activated mortar reinforced by polyvinyl alcohol fiber is presented. In the development, three mixtures having a viscosity range that promotes uniform fiber dispersion were determined according to the types of alkali-activator and water to binder ratio. A series of experiments, including density, compression, uniaxial tension and panel bending tests were carried out to characterize the mechanical properties of the composite. Test results establish the feasibility of attaining tensile strain up to 4.7% in fiber reinforced alkali-activated slag composite, compared with 0.020% for the mortar matrix alone. 2012-01-01T00:00:00Z