This article surveys the research and development of Engineered Cementitious Composites (ECC) over the last decade since its invention in the early 1990's. The importance of micromechanics in the materials design strategy is emphasized. Observations of unique characteristics of ECC based on a broad range of theoretical and experimental research are examined. The advantageous use of ECC in certain categories of structural, and repair and retrofit applications is reviewed. While reflecting on past advances, future challenges for continued development and deployment of ECC are noted. This article is based on a keynote address given at the International Workshop on Ductile Fiber Reinforced Cementitious Composites (DFRCC) - Applications and Evaluations, sponsored by the Japan Concrete Institute, and held in October 2002 at Takayama, Japan.

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On Engineered Cementitious Composites (ECC)

This paper presents the development of the PVA-ECC in the context of material design under the guidance of micromechanical tools. Specifically, this work illustrates how the fiber/matrix interface may be engineered to accommodate the requirements imposed by the micromechanical models, thus highlighting the importance of interface tailoring on the composite performance. This micromechanics-based material design approach is broadly applicable to achieving high-performance composites with low fiber content for cost-effective structural applications.

Interface tailoring for strain-hardening polyvinyl alcohol-engineered cementitious composite (PVA-ECC)

Concrete is very sensitive to crack formation. As wide cracks endanger the durability, repair may be required. However, these repair works raise the life-cycle cost of concrete as they are labor intensive and because the structure becomes in disuse during repair. In 1994, C. Dry was the first who proposed the intentional introduction of self-healing properties in concrete. In the following years, several researchers started to investigate this topic. The goal of this review is to provide an in-depth comparison of the different self-healing approaches which are available today. Among these approaches, some are aimed at improving the natural mechanism of autogenous crack healing, while others are aimed at modifying concrete by embedding capsules with suitable healing agents so that cracks heal in a completely autonomous way after they appear. In this review, special attention is paid to the types of healing agents and capsules used. In addition, the various methodologies have been evaluated based on the trigger mechanism used and attention has been paid to the properties regained due to self-healing.

https://biblio.ugent.be/publication/4144354/file/4144368.pdf

Self-Healing in Cementitious Materials—A Review

http://www.drfixitinstitute.com/download/rebuild_2010/Rebuild%20vol%204%20no%204%20Oct-Nov%202010/Rebuild%20Vol.%204%20No.%204%20Oct-Dec%203rd.pdf

Autogenous healing of engineered cementitious composites under wet–dry cycles

A review : Self-healing in cementitious materials and engineered cementitious composite as a self-healing material

A high-performance polyvinyl alcohol fiber-reinforced engineered cementitious composite (PVA-ECC) was developed for structural applications under the performance-driven design approach. Fiber, matrix, and fiber/matrix interfacial properties were tailored to micromechanics models to satisfy the pseudo strain-hardening condition. This research experimentally investigated the effects of fiber surface treatment and sand content on the composite performance. Results from uniaxial tensile tests show an ultimate strain exceeding 4%, as well as an ultimate strength of 4.5 MPa for the composites, with a moderate fiber volume fraction of 2%. The specimens reveal saturated multiple cracking with crack width at ultimate strain limited to below 100 nanometers. The underlying reason of the distinctly different tensile behavior between normal fiber-reinforced concrete and PVA-ECC is highlighted by the comparison of complementary energy from their fiber bridging stress and crack opening curves.

Tensile strain-hardening behavior of polyvinyl alcohol engineered cementitious composite (pva-ecc)

Engineered cementitious composites (ECCs) are a breed of high-performance fiber-reinforced cementitious composites (HPFRCC) with significant strain-hardening behavior under tension. As ECCs impart ductility and durability to the structure, the high cement usage in the mixture causes environmental and economical impacts. In this paper, the mechanical performance of ECCs incorporating high volume fly ash and bottom ash is reported. Emphasis is placed on the influence of fly ash content on the key micromechanics properties relevant to composite ductility. It is revealed that a high volume faction of fly ash tends to reduce the polyvinyl alcohol (PVA)fiber/matrix interface bond and matrix toughness in favor of attaining high tensile strain capacity. The limit of cement substitution with ash is constrained by compressive strength development.

Engineered Cementitious Composites with High-Volume Fly Ash

This paper is on modeling and measuring fiber-bridging constitutive law of Engineered Cementitious Composites (ECC), a high performance fiber-reinforced cementitious composite featuring high tensile ductility. Fiber-bridging constitutive law plays an important role in the multiple cracking behavior of ECC. Therefore, proper control of fiber-bridging behavior through tailoring material microstructure is the key to successfully designing tensile strain-hardening ECC. In this paper, an analytical fiber-bridging model of ECC which connects material constituent parameters and composite properties, built on a previous simplified version, was proposed. To improve accuracy of crack opening prediction, new mechanisms of fiber/matrix interactions, specifically fiber two-way debonding and pull-out, matrix micro-spalling, and Cook-Gordon effects were included. This revised model was compared with experimental measurement of fiber-bridging behavior and the validity of the model was confirmed. It is expected that this model will greatly improve ECC design technology in terms of steady-state crack width control, key for structural long-term durability, and in terms of composite tensile properties important for structural safety at ultimate limit state.

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Fiber-Bridging Constitutive Law of Engineered Cementitious Composites

Polyvinyl alcohol (PVA) fiber is considered as one of the most suitable polymeric fibers to be used as the reinforcement of engineered cementitious composites (ECC), though the unique microstructure characteristics of PVA fiber add challenge to the material design. In this paper, the micromechanics based design procedure for a PVA-ECC suitable for structural applications is described, and practical design considerations including requirements on interface bond, matrix toughness, and flaw system are outlined for achieving balanced composite performances. The properties of an exemplary PVA-ECC design are summarized, including tensile behavior and compressive strength development, bending response, Young’s modulus, autogenous and drying shrinkage, and freeze-thaw durability.

Shuxin Wang

Papers

Tensile strain-hardening behavior of polyvinyl alcohol engineered cementitious composite (pva-ecc)

Interface tailoring for strain-hardening polyvinyl alcohol-engineered cementitious composite (PVA-ECC)

Engineered Cementitious Composites with High-Volume Fly Ash

Fiber-Bridging Constitutive Law of Engineered Cementitious Composites

Polyvinyl Alcohol Fiber Reinforced Engineered Cementitious Composites: Material Design and Performances