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Journal Jun 2020

Behavior of Engineered Cementitious Composite Structural Elements – A Review Preethy Mary Arulanandam, S. B. Singh, Toshiyuki Kanakubo, Madappa V. R. Sivasubramanian

In this article, a comprehensive review is conducted to summarize the research and development on Engineered Cementitious Composites (ECC) over the decades emphasizing on its structural behavior. Critical observations on flexural and shear load capacity, ductility, cracking behavior and failure patterns of ECC structural members are examined and summarized. Then, the ability of ECC towards the flexural and shear strengthening applications are fully studied and reported. Further, the performance of ECC against impact and seismic loading conditions are exhaustively studied and significant interpretations are provided. This review concludes that the use of ECC enhances the performance of the structural elements significantly as a superior construction material.

Effect of Fiber Content on the ECC Bridging Stress-crack Opening Behavior and Flexural Strain Hardening Properties Rongxin Guo, Chaoshu Fu, Yang Yang, Feng Yan

Four different polyvinyl alcohol engineered cementitious composite (PVA-ECC) composites with different fiber contents were prepared. Single crack tension tests and four-point bending tests were used to determine the bridging stress-crack opening relationship ( σ – δ relationship) and bending load-deflection relationship of specimens with a curing age of 28d. The effects of the PVA fiber content on the bridging stress-crack opening behavior and flexural strain hardening properties of the ECCs were investigated. Experimental results showed that peak bridging stress increased in proportion to the fiber content, but the crack opening displacement decreased initially and then increased when fiber content changed from 1.4% to 2.3%. Furthermore, the fiber content had no significant effect on the ultimate bending strength of specimens, and the mid-span deflection increased with the increase of the fiber content. The optimal strain hardening property was obtained when the PVA fiber content reached 2%, but the addition of PVA fibers in excess of 2% resulted in a decrease in the strain hardening properties of the ECCs. A simple analytical method for determining the optimum content of fibers was proposed. The strain hardening index calculated by this method was in good agreement with the experimental value, and can well reflect the strain hardening property of the ECCs.

Optimization of Low-Cost Polyvinyl Alcohol (PVA) Fiber Reinforced Engineered Cementitious Composites (ECC) for Practical Applications Shan, K. A., Ratnayake, D., Jing Yu, Dhanada K. Mishra, Christopher K. Y. Leung

Engineered Cementitious Composite (ECC) with unique tensile strain-hardening and multiple-cracking properties is an advanced construction material that can enhance resiliency and durability of structures. However, the high cost of the constituents limits the wide spread application of ECC. A relatively low-cost ECC formulation having adequate compressive and tensile properties was developed in this study by using low-cost Chinese PVA fiber with the optimisation of water/binder, sand/binder and fly ash/binder ratios. Such a mix can save steel reinforcement from a reinforced concrete section to be cost-competitive. This opens up a wider range of applications for ECC in real-life.

Experimental Behaviour of Hybrid Fiber Reinforced Engineered Cementitious Composites for Concrete Pads Supporting Joint Strike Fighter F35-B Ezgi Gurbuz, Savas Erdem

The present research emphasizes on the performance characteristics of hybrid fiber reinforced Engineered Cementitious Composites (ECC) produced for concrete pads supporting joint strike fighters F35-B. Four mixes using polyvinyl alcohol fiber, basalt fiber and micro steel fiber were produced and subjected to temperatures reaching to 900°C. The performance of various combinations was evaluated by assessing the changes in compressive strength, impact flexural energy, Rebound Hammer Number. In addition, 3D image analysis technique and fractal theory were adopted for the numerical assessment of the cracks. It has been concluded that the hybridization of different fibers in ECC enhanced the mechanical performance under high temperatures.

Correlation of Dynamic and Static Modulus of Elasticity of UHPC Bharathi Ganesh, Ramesh M. N., Santhosh K., Manoj V.

Modulus of Elasticity of concrete is an important parameter which shows the ability of concrete to deform elastically. Ultra-High Performance Concrete (UHPC), also being of ultra-high strength, requires higher Modulus of Elasticity to maintain its stiffness, to prevent excessive deformation, leading to cost effective design and longer durability. The present experimental study correlates the Static and Dynamic Modulus of Elasticity of UHPC with and without coarse aggregates. The mix design of UHPC is validated and modified, optimising the density using Particle Packing approach for arriving at design mix proportions. Binders and fillers are replaced with 5% metakaolin, 10% micro silica and 20% quartz powder along with well graded aggregates (up to Nano level). The 28day compressive strength was assessed as per IS 516-1959 procedures and an average strength of 75 to 80MPa could be achieved for the mixes at W/B ratio of 0.3 and 90-100MPa at a W/B ratio of 0.22. Dynamic Modulus of Elasticity (Ed) computed using UPV test (Ed=53.2GPa to 60.1GPa) and Static Modulus Elasticity (Es) of cylindrical specimens determined experimentally as per the standard procedure mentioned in IS 516:1959 (range of Es=59 to 62.2GPa) are correlated graphically. The correlation between (Ed) and (Es) obtained for the mix with coarse aggregates and without coarse aggregates is negligible.

Performance Characteristics of ECC using Micro Fibers in Hybridization Maninder Singh, Babita Saini, H. D. Chalak

The present research emphasizes on the performance characteristics of ECC by hybridization of micro fibers. Seven mixes along with polyvinyl alcohol (PVA) fiber, polyester (PET) fiber and micro steel (MS) fiber were prepared. From the total volume fraction of PVA fiber used in this study 25% was switched by PET fiber at dosage 5%, 10%, 15%, 20%, 25% and another 25% by MS fiber. The performance of various combinations was evaluated by assessing flexural response, electrical resistivity, air permeability and sorptivity characteristics. From this study, it has been concluded that the hybridization of fibers showed the enhancement in flexural and durability performance of ECC.

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