Karma Lifli Betonların Tek Eksenli Çekme Altında Çatlak Yapısının İncelenmesi

Year 2020, Volume: 31 Issue: 1, 9773 - 9787, 01.01.2020

Burcu Akçay Aldanmaz

https://doi.org/10.18400/tekderg.419819

Cited By: 3

Abstract

Karma lifli betonların kırılmasında lif hacmi ve lif boyutunun etkisi
tek eksenli çekme deneyi ile belirlenmiştir. Kemik şeklindeki numuneler serbest
dönen mafsallı yükleme düzeneğinde tek eksenli çekme altında yüklenmiştir.
Deney sonuçları lif hacmi arttıkça hem çekme dayanımının hem de yük-deplasman
grafiğinin altında kalan alanın yani betonun tokluğunun arttığını göstermiştir. Kısa liflerin yalnızca
tepe yükünü arttırmadığı uzun lifler ile birlikte karma olarak kullanıldığında
tepe yükünden sonraki davranışa da etkiyerek tokluğu da arttırdığı görülmüştür.
Görüntü analizleri karma lifli betonlarda çatlağın hiçbir zaman doğrusal
olmadığını, betonun iç kısımlarına ilerledikçe dış yüzeyde görünmeyen çoklu
çatlamanın, dallanma ve köprülenmenin bulunduğunu göstermiştir. Kısa lifler
arttıkça ortalama çatlak alanı belirgin bir şekilde artarken uzun liflerin
miktarı arttıkça en büyük çatlak açıklığının arttığı belirlenmiştir.

Keywords

Çatlak yapısı, dijital görüntü analizi, karma lifli beton, lif geometrisi, lif hacmi

Crack Pattern Investigation of Hybrid Fibre Reinforced Concrete under Uniaxial Tension

Abstract

The
effect of size and volume of fibres on the fracture of hybrid fibre reinforced
concrete was determined by applying uniaxial tensile test. The bone shaped
specimens were loaded under uniaxial tension by using freely rotated support
loading test setup. The test results showed that the increase in fibre volume
results in an increase in both tensile strength and the area under the load
displacement curve, which is the measure of the material toughness.
It was shown that the use of short fibres not only increased the peak load but
also affected the post-peak behaviour and increased the toughness especially
when they were used together with long fibres. The image analyses pointed out
that in hybrid fibre reinforced concrete the crack patterns are not in general
linear. Instead, the cracks propagate inside the samples forming multiple
cracks and crack branches as well as developing bridging, though these features
are not observed on the surface of the samples. The results showed that with
increasing amount of short fibres the average crack area was increased, while
the use of long fibres in more abundance increased the width of the largest
crack. 

Keywords

Crack pattern, digital image analysis, hybrid fibre reinforced concrete, fibre geometry, fibre volume, uniaxial tensile test

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