Evaluation of the Fiber Bond Strength in Lightweight Aggregate Concrete

نوع: Type: Thesis

مقطع: Segment: masters

عنوان: Title: Evaluation of the Fiber Bond Strength in Lightweight Aggregate Concrete

ارائه دهنده: Provider: Milad Niyazi

اساتید راهنما: Supervisors: Dr. Mahmoud Nili

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Dr. Seyed Mahdi Hosseinian - Dr. Amir Rezaei Sameti

زمان و تاریخ ارائه: Time and date of presentation: 2025

مکان ارائه: Place of presentation: 44

چکیده: Abstract: .Today, in seismic-prone regions, reducing the structural weight is of paramount importance. In this regard, the use of lightweight concrete in structures, as one of the most effective methods for reducing seismic forces, has attracted the attention of researchers. However, since sufficient information on the behavior of lightweight concrete in various types of structures is lacking, its use in structures is practically limited. In the present thesis, 10 mix designs with a water-to-cement ratio of 0.37 were prepared. Two types of lightweight aggregates, Leca and Scoria, were used separately and in combination as part of the coarse aggregate at percentages of 35%, 40%, and 45%. Silica fume was used at 10% by weight of cement in the mixes. In addition to compressive strength, tensile strength, and water absorption tests to gather basic information, the pull-out force and bond strength of fibers in lightweight concrete were evaluated. Furthermore, using a numerical method, the friction coefficient and pull-out force of fibers with different end hooks were calculated. The results showed that using a combination of Scoria and Leca lightweight aggregates led to an increase in bond strength, compressive strength, and tensile strength. The bond strength results indicated the significant effect of the end hook, such that the maximum pull-out force of 3D, 4D, and 5D hooked-end fibers compared to straight fibers increased by factors of 2.1, 3.8, and 6, respectively, in lightweight concrete. These results highlight the effectiveness of hooked-end steel fibers in improving bond strength and make hooked-end fibers highly suitable for use in concrete with structural purposes. A comparison of experimental and numerical results for fiber pull-out force indicates the appropriate accuracy of the proposed relationships. The data obtained in this thesis can be used as key information for calculating the energy index and bond strength. This outcome can serve as a bridge between material properties and structural behavior in fiber-reinforced concrete