Kasım MERMERDAŞ, Zeynep ALGIN, Mehmet ŞEKER

Yüksek Sıcaklığın Cam Elyaf Takviyeli Polimer Donatı ile Beton Arasındaki Aderans Dayanımına Etkisi

Elyaf takviyeli polimer donatının, yüksek korozyon direncine ve yüksek çekme dayanımına sahipolmasının yanında hafif bir malzeme olmasından dolayı, geleneksel çelik donatının yerinekullanılabileceği düşünülmektedir. Elyaf takviyeli polimerlerin, betonun içinde donatı olarakkullanılabilirliğindeki en kritik sorunlardan biri de aderans dayanımıdır. Donatı ile beton arasındakiaderans dayanımı beton sınıfı, donatının türü, çapı, gömülme derinliği, yüzey özellikleri gibi birçokfaktöre bağlıdır. Bu çalışmada, cam elyaf takviyeli polimer (CETP) donatı çapının (18, 16, 14 ve 12 mm),beton sınıfının (C20 ve C40) ve yüksek sıcaklığın (150 ve 250 oC), CETP donatı ile beton arasındakiaderans dayanımına etkisi araştırılmıştır. Çalışmanın ilk aşamasında, C20 ve C40 sınıfında hazırlananbeton karışımlar ve dört farklı çaptaki CETP donatıları kullanılarak üretilen numunelere sıyrılma testiuygulanmış olup, donatı çapındaki ve beton sınıfındaki değişimin aderans dayanımı üzerindeki etkisiincelenmiştir. Çalışmanın ikinci aşamasında ise, C20 ve C40 sınıfındaki beton karışımlar için 12 ve 16 mmçapındaki CETP donatılar kullanılarak hazırlanan numuneler, 3 saat süre ile 150 ve 250 oC sıcaklıklaramaruz bırakılmıştır. Daha sonra oda sıcaklığına kadar soğutulan numunelere sıyrılma testi uygulanarak,yüksek sıcaklığın aderans dayanımı üzerindeki etkisi incelenmiştir. Bu çalışmanın sonucunda, CETPdonatı çapı arttıkça aderans dayanımının arttığı, betonun basınç dayanımındaki artışın da aderansdayanımını olumlu yönde etkilediği görülmüştür. Ayrıca, sıcaklık artışının CETP donatı ile betonarasındaki aderansı olumsuz yönde etkilediği belirlenmiştir.

The Effect of Elevated Temperature on Bond Strength between Glass Fibre Reinforced Polymer Bar and Concrete

The utilisation of fibre reinforced polymer (FRP) bars in concrete instead of the conventional steel rebar is generally considered to be viable due to their fundamental traits such as lightweight, higher corrosion resistance and tensile strength. One of the most critical issues in this FRP application is in fact the bond strength between FRP bars and concrete which depends on many factors including the strength of concrete, FRP diameters, types, embedment depth and surface properties etc. In this study, the effects of bar diameters (18, 16, 14 and 12 mm), the strength classes of concrete (C20 and C40) and the elevated temperature (150 and 250 oC) variation on the bond strength were investigated. In the first stage of the study, the pull-out tests were applied to the samples produced by using concrete mixtures prepared as C20 and C40 class and FRP reinforcements having four different diameters. Thus, the effects of variation in FRP diameter and the strength classes of concrete on the bond strength were investigated. In the second stage of the study, the samples prepared using 12 and 16 mm diameters of FRP reinforcements for C20 and C40 concrete mixtures were exposed to the temperatures of 150 and 250 oC for 3 hours. Then, the effect of elevated temperature on the bond strength was carried out by applying the pull-out tests to the samples cooled to the room temperature. The test results reveal that the bond strength is improved with increasing FRP diameter, the compressive strength of concrete and

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