Civil Engineering / İnşaat Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/13

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Institution Author: search.filters.institutionAuthor.Erdem, Tahir KemalSubject: search.filters.subject.Engineered Cementitious Composites

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Now showing 1 - 4 of 4
  • Article
    Citation - WoS: 55
    Citation - Scopus: 64
    High-Early Ductile Cementitious Composites With Characteristics of Low Early-Age Shrinkage for Repair of Infrastructures
    (Springer Verlag, 2015) Şahmaran, Mustafa; Al-Emam, Muhannad; Yıldırım, Gürkan; Şimşek, Yunus Emre; Erdem, Tahir Kemal; Lachemi, Mohamed
    Reduced performance in concrete infrastructures is mainly caused by the formation of cracks, which may arise due to deteriorating mechanisms during service life. In most cases, reduced performance calls for urgent repairs to the degraded section. Therefore, it is highly desirable to develop dimensionally stable, ductile repair materials that can attain adequately high strength in a limited amount of time, compensate for significant deformation due to mechanical and environmental loadings, and prevent early-age shrinkage cracks. In this paper, the performance of such a material (high-early-strength engineered cementitious composites, HES-ECC, with very low early-age shrinkage capacity) was investigated by studying mechanical properties and dimensional stability. Composites were produced with different water to cementitious materials and slag to Portland cement ratios. In order to enhance composite properties in terms of ductility and early-age shrinkage characteristics, saturated lightweight aggregates replaced sand in the mixtures. The experimental results show that the majority of HES-ECC mixtures developed in this study attained compressive strength values of more than 20.0 MPa and minimum flexural strength of 6.0 MPa within 6 h. Moreover, the HES-ECC mixtures exhibited strain-hardening behavior with strain capacities comparable to normal strength ECC, as well as substantially reduced autogenous shrinkage strain, both of which are unlikely to trigger the formation of cracks in tension at early ages. The integration of these conflicting parameters suggests that HES-ECC can easily meet the need for fast and durable repairs.
  • Article
    Citation - WoS: 62
    Citation - Scopus: 75
    Specimen Size Effect on the Residual Properties of Engineered Cementitious Composites Subjected To High Temperatures
    (Elsevier Ltd., 2014) Erdem, Tahir Kemal
    In this study, size effect on the residual properties of Engineered Cementitious Composites (ECC) was investigated on the specimens exposed to high temperatures up to 800 C. Cylindrical specimens having different sizes were produced with a standard ECC mixture. Changes in pore structure, residual compressive strength and stress-strain curves due to high temperatures were determined after air cooling. Experimental results indicate that despite the increase of specimen size, no explosive spalling occurred in any of the specimens during the high temperature exposure. Increasing the specimen size and exposure temperature decreased the compressive strength and stiffness. Percent reduction in compressive strength and stiffness due to high temperature was similar for all specimen sizes.
  • Article
    Citation - WoS: 278
    Citation - Scopus: 309
    Self-Healing Capability of Cementitious Composites Incorporating Different Supplementary Cementitious Materials
    (Elsevier Ltd., 2013) Şahmaran, Mustafa; Yıldırım, Gürkan; Erdem, Tahir Kemal
    The presence of deleterious substances and their transport are among the most important factors controlling the durability of cementitious composites. The present paper studies the relationship among the applied mechanical deterioration in terms of splitting tensile deformation, curing conditions and chloride ion permeability of Engineered Cementitious Composites (ECCs) that contain different supplementary cementitious materials (SCMs). Three SCMs, representing a wide range of compositions, were used in the study. The splitting tensile deformations are introduced to generate microcracks in ECC specimens, where cylindrical specimens were pre-loaded to different deformation levels. After that, the mechanically pre-cracked and pristine ECC specimens were exposed to three different curing conditions (continuous wet, continuous air, and freeze-thaw cycle) for up to 2 months. Rapid chloride permeability test (RCPT), microscopic observation and microstructural analysis were used to assess the rate and extent of self-healing. Test results indicate that the SCM type greatly affects the self-healing capability of cementitious composites as measured by chloride ion permeability. Although ECC samples with fly ash have more unhydrated cementitious materials, and therefore, expectedly, a higher capacity for self-healing, more evident self-healing product was observed from the ECC mixture incorporating slag. Therefore, in addition to the crack width distribution and curing condition, the reaction products associated with SCMs have a great impact on the self-healing capability of cementitious composites.
  • Article
    Citation - WoS: 77
    Citation - Scopus: 93
    Improving the Workability and Rheological Properties of Engineered Cementitious Composites Using Factorial Experimental Design
    (Elsevier Ltd., 2013) Şahmaran, Mustafa; Bilici, Zafer; Özbay, Erdoğan; Erdem, Tahir Kemal; Yücel, Hasan Erhan; Lachemi, Mohamed
    In the development of Engineered Cementitious Composites (ECC), micromechanics-based design theory is adopted to properly select the matrix constituents, fiber, and fiber-matrix interface properties to exhibit strain hardening and multiple cracking behaviors. Despite the micromechanics design constraints, practical applications show that the workability and rheological properties of matrix can affect the fiber dispersion uniformity, which have also direct concerns on composite mechanical properties. For this reason, in this research, parameters of micromechanics-based optimized ECC mixture design, which most possibly affecting the workability and rheological properties, are investigated. An experimental program that contains 36 different ECC mixtures was undertaken to quantitatively evaluate the combined effects of the following factors on workability and rheological properties: water-binder (w/b), sand-binder (s/b), superplasticizer-binder (SP/b) ratios and maximum aggregate size (Dmax). A mini-slump cone, a Marsh cone and a rotational viscometer were used to evaluate the workability and rheological properties of ECC mixtures. Compressive strength and four point bending tests were used for mechanical characteristics of ECC mixtures at 28 days. The effects of studied parameters (w/b, s/b, SP/b and Dmax) were characterized and analyzed using regression models, which can identify the primary factors and their interactions on the measured properties. Statistically significant regression models were developed for all tested parameters as function of w/b, s/b, SP/b and Dmax. To find out the best possible ECC mixture under the range of parameters investigated for the desired workability and mechanical characteristics, a multi-objective optimization problem was defined and solved based on the developed regression models. Test results indicate that w/b, s/b and SP/b parameters affect the rheological and workability properties. On the other hand, for the range of studied aggregate sizes, Dmax is found to be statistically insignificant on the rheological and workability properties of ECC.