Browsing by Author "Eyice, Doga"

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Citation Count: 30
Evaluation of enhanced autogenous self-healing ability of UHPC mixtures
(Elsevier Sci Ltd, 2021) Beglarigale, Ahsanollah; Beglarigale, Ahsanollah; Tutkun, Bayram; Yazici, Halit; İnşaat Mühendisliği / Civil Engineering
Enhancing and characterization of self-healing ability of ultra high performance concrete (UHPC) is the main aim of this study. The self-healing mechanisms of macro/micro cracks were investigated through different techniques with some novel procedures. Two different mix designs have been considered to increase the amount of unreacted particles in the matrix. In spite of the positive effect of supplementary cementitious materials (SCM) on self-healing ability of UHPC, it was observed that the detected self-healing ratios depend on critical parameters such as damage type/level and the methods used to verify the phenomenon of self-healing. Depending on the composition of the UHPC mixtures, the age of specimens and the assessing method, up to 70-76% recoveries were obtained in the compressive strength and permeability of specimens pre-loaded up to -400% of their corresponding compressive strength. In addition, up to 88-100% crack sealing was observed in the pre-cracked UHPC specimens assessed via various methods. (C) 2021 Elsevier Ltd. All rights reserved.
Citation Count: 4
Novel Test Method for Assessing Bonding Capacity of Self-Healing Products in Cementitious Composites
(Asce-amer Soc Civil Engineers, 2019) Beglarigale, Ahsanollah; Beglarigale, Ahsanollah; Eyice, Doga; Yazici, Halit; İnşaat Mühendisliği / Civil Engineering
Many tests and methods can be used to assess or verify the self-healing mechanisms of cement-based materials. This study, which is part of wider project, deals with the development and application of a test method for studying the self-healing ability of cementitious composites. The principle of this method lies in the bonding capacity of self-healing products under direct tension loads. A specially designed cylinder specimen was split after 7 days of water curing, and then the two parts of the split specimen were carefully put together immediately. A connector apparatus was designed to keep the surface of each part connected to each other with equal pressure for the "healing" process in water. After 30 days, the specimens were tested by a special direct tension test method to evaluate the bond loads. In addition, the crack-closing ratios were monitored on precracked disc-shaped specimens. The bond loads of 7 different ultra-high-performance concrete (UHPC) mixtures were compared with the crack-closing ratios. The healing process in the novel test, which simulated the self-healing of very narrow cracks, was observed to differ from the crack-closing test method. Considerable bond loads were obtained in both fly ash (308 N) and ground granulated blast furnace slag (GGBFS) (210 N) bearing mixtures. Additionally, the maximum crack-closing ratio (100%) was observed in the GGBFS bearing mixture. (c) 2019 American Society of Civil Engineers.
Citation Count: 14
Sodium silicate/polyurethane microcapsules synthesized for enhancing self-healing ability of cementitious materials: Optimization of stirring speeds and evaluation of self-healing efficiency
(Elsevier, 2021) Beglarigale, Ahsanollah; Beglarigale, Ahsanollah; Seki, Yoldas; Yalcinkaya, Caglar; Copuroglu, Oguzhan; Yazici, Halit; İnşaat Mühendisliği / Civil Engineering
In this study, stirring speeds during the synthesizing process of the sodium silicate/polyurethane microcapsules were optimized. The yield values of micmcapsules at different stirring rates were evaluated. Based on the yield values and shape of microcapsules, optimized microcapsules were obtained. The measurements of the shell thickness of microcapsules were performed on the fractured microcapsules by using scanning electron microscopy. The optimized micmcapsules were further characterized by means of optical microscopy and nanoindentation. Load vs. displacement and modulus of elasticity vs. displacement characteristics of the microcapsules were obtained. The average modulus of elasticity was found to be 633 MPa. The self-healing efficiency of the optimized micmcapsules was evaluated by means of compressive strength tests. The incorporation of micmcapsules reduced the compressive strength of fiber-reinforced mortar by 12-22%. However, it was observed that the microcapsules enhanced the self-healing capacity (recovery in compressive strength) of the mortar.