Journal Dec 2019

Effect of passive confinement provided from Engineered Cementitious Composites (ECC) cover on corrosion of steel reinforcement Zhitao Chen, Xin Qin, Khin Phyu Phyu Thaw, En-Hua Yang

This paper investigates the effect of passive confinement provided from ECC cover on corrosion of steel reinforcing bars. ECC and fibre-reinforced concrete (FRC) with different fibre dosage are used as cover materials to provide different levels of passive confinement to the steel reinforcement subject to corrosion. Results showed that specimen with ECC cover showed significant performance improvement with reduced mass loss and mass loss rate of steel reinforcement  and increased residual flexural load capacity. The fundamental change of failure mode of cover material from brittle to ductile is the key to enhance the corrosion resistance in R/C.

Development of Sustainable Engineered Cementitious Composite (ECC) with Ternary Industrial Solid Wastes and Cost-Effective PVA Fibres Yudong Han, Qing Wang, Boyu Yao

Engineered Cementitious Composite (ECC) with ductile strain-hardening and fine multiple cracking behaviors has been recognized as a type of advanced and resilient alternative to conventional concrete materials. However, the high cost of the constituents, mainly associated with high cement content and large consumption of expensive polyvinyl alcohol (PVA) fibres, limits the wide application of ECCs. To improve the sustainability and reduce the material cost as well, latest efforts were made by applying green binders with industrial wastes and/or recycled fibres. Herein, this study focuses on the potential use of industrial solid wastes (ISWs) including silica fume (SF), fly ash (FA) and ground granulated blast furnace slag (GGBFS), and lowcost PVA fibres produced by local synthetic fibre factory. Firstly, new matrixes incorporating with ternary industrial solid wastes were designed and optimized through partially substituting cement by successive steps. Then mechanical properties of costeffective PVA-ECC were experimentally evaluated. Results show that even if as much as 50% of Portland Cement is replaced with ISWs, ECC with local PVA fibres still maintains strain-hardening and multiple cracking behaviors accompanied by a tensile strain capacity up to 1.0%. Such improvement may significantly reduce the environmental impact and material cost, and is expected to greatly promote the field applications of ECC with local ingredients.

Influence of Fibre Length on the Mechanical Behavior of Steel-PVA Hybrid Fibre-Reinforced Strain-Hardening Cementitious Composites at High Temperatures Dhanendra Kumar, Alok A. Deshpande, Ravi Ranade

Residual mechanical properties, after exposure to temperatures of up to 800ºC, of Hybrid Fibre-Reinforced Strain-Hardening Cementitious Composites (HFR-SHCCs) utilizing steel and polyvinyl alcohol (PVA) fibres are reported in this article. The main objective is to investigate the influence of the length of the steel fibres (13 and 25 mm) on the behavior of HFR-SHCCs. While the HFR-SHCC with 13 mm steel fibres exhibits lesser micro-cracking and greater compressive strength at room temperature than that of the HFR-SHCC with 25 mm steel fibres, the latter material shows better tensile performance at high temperatures than the former material due to higher aspect ratio of the steel fibres.

Electrical Testing for the Assessment of Self-Healing and Self-Sensing Capability of Cementitious Composites Oguzhan Sahin, Gurkan Yıldırım, Mustafa Sahmaran

Engineered Cementitious Composites (ECC) is regarded as a multifunctional smart material due to its intrinsic autogenous self-healing and self-sensing attributes. Here, recent findings related to the utilization of electrical measurements in analyzing combined effectiveness of autogenous self-healing and self sensing attributes in ECC are discussed. It is concluded that electrical testing which are already widely used for self-sensing, can also be used successfully in estimating the autogenous self healing efficiency in ECC. It is believed that further research into developing/understanding methods to rapidly and accurately characterize the multifunctional properties of such smart materials will significantly fasten their development and wider practical adoption.

Sulfuric Acid Resistance of Strain Hardening Fibre Reinforced Geopolymer Composite Motohiro Ohno, Victor C. Li

This paper reports on sulfuric acid resistance of a strainhardening fibre-reinforced geopolymer composite, named Engineered Geopolymer Composite (EGC). EGC is a promising material for durable and resilient wastewater infrastructure applications due to its acid-resistant geopolymer matrix and high tensile ductility along with self-controlled microcracking. In the present study, the weight loss, residual compressive and flexural strengths, and deflection capacity of acid-exposed EGC specimens are experimentally investigated. In comparison with normal cement concrete and Engineered Cementitious Composite (ECC), EGC exhibited a three times slower rate of weight loss and no significant degradation in mechanical performances.

Stress-Strain Behaviour and Performance Evaluation of High Strength Steel Fibre Reinforced Concrete (SFRSHC) V. V. Arora, Brijesh Singh, Vikas Patel, Y. N. Daniel, B. N. Mohapatra

High strength concrete exhibits several desirable mechanical properties for structural application in seismic regions and repair / rehabilitation of hydraulic structures among others. The damage on concrete surfaces caused by the abrasive action of waterborne solid particles at high velocity is one of the major issue while designing the operation of hydraulic structures like spillways, glacis etc. This paper highlights the study of mechanical properties of steel fibre-reinforced high strength concrete (SFRSHC) with trough and hooked-end steel fibres with 0.55 mm diameter and 35 mm length (aspect ratio: 63) satisfying the requirements of ASTM A-820. The concrete mixes with three different water/binder ratios (0.47, 0.36 and 0.20) was used in the study. The stress-strain behavior under uniaxial compression test has been investigated by varying concrete compressive strength and fibre volume fraction. Splitting tension, uniaxial compression, abrasion, impact and toughness measurements were carried out using 0%, 1%, 1.25%, 1.5% and 2.5% steel fibres by volume of concrete and results are presented. Study highlights that High Strength Steel Fibre Reinforced Concrete (HSSFRC) can be utilized in hydraulic structures for sustainable construction and durable repair.

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