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Mechanical and Electrical Properties Evaluation of Conductive Concrete Matrix
EL Afandi, Mohammed Adnan
EL Afandi, Mohammed Adnan
Date
2021-06
Authors
Type
Thesis
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Description
A Master of Science thesis in Civil Engineering by Mohammed Adnan EL Afandi entitled, “Mechanical and Electrical Properties Evaluation of Conductive Concrete Matrix”, submitted in June 2021. Thesis advisor is Dr. Sherif Yehia and thesis co-advisors are Dr. Taha Landolsi and Dr. Nasser Qaddoumi. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).
Abstract
Conductive concrete is a material that can conduct electricity through conductive fillers, commonly made from graphite, carbons, and steel fibers. Thanks to its conductive nature, this type of concrete can be utilized in multiple applications such as deicing, electromagnetic shielding, and traffic monitoring. However, issues can arise when adding conductive concrete to a new or existing structure. It is addition might affect the structural capacity and integrity. Therefore, concrete to concrete bond strength needs to be investigated to ensure continuous serviceability. This thesis presents an experimental study to characterize the mixes’ mechanical properties, the concrete-to-concrete bond strength, and the electrical properties of conductive concrete. Moreover, a self-consolidated concrete mix is used for all control samples and in concrete-to-concrete bond study. The mixes’ mechanical properties are evaluated using compression, modulus of elasticity, flexural third point loading, split tension, and direct shear tests. To evaluate the concrete-to-concrete bond strength, slant shear test with the addition of beforementioned tests are used except for split tension and direct shear tests. Furthermore, the conductive concrete electrical properties, namely its resistivity, are measured and analyzed as the material aged. The experimental results show that the compressive strength and the stiffness of the conductive concrete mix used in this study are approximately 13% and 35% lower than those of the self-consolidated concrete, respectively. The presence of steel fibers in the conductive concrete mix has improved the flexure strength and split tension 4 times, as well as direct shear 2.4 times of the self-consolidated concrete’s strength. Moreover, the best surface preparation technique in concrete-to-concrete bond strength is the shear key method. Additionally, the presence of conductive concrete layer at the tensile region yields the highest flexural strength, as observed in flexural tests. Furthermore, conductive fillers have improved the conductivity of the material. Moreover, steel fibers have improved the conductive concrete mix by further lowering the conductive concrete’s resistivity from 30 kΩ.mm to 0.5 kΩ.mm. Finally, a linear relationship is present between the compressive strength and the resistivity of the conductive concrete with respect to concrete aging.