ELECTRICAL RESISTANCE OF HYBRID STEEL FIBER REINFORCED SELF- COMPACTING CONCRETE

Öz

Concrete has high compressive strength as well as very low conductivity. In this study, the effect of long and short steel fibers on electrical resistivity, conductivity and temperature rise of self-compacting concrete (SCC) was investigated depending on fiber combinations (single and binary hybrid) and length of the short steel fibers (6 and 13 mm). For this purpose, four mixtures were designed: non-fiber reference, a single fiber-reinforced mixture with only long fibers and two hybrid steel fiber-reinforced mixtures with long and 6mm or 13 mm short steel fiber. Also, all steel fiber-reinforced mixtures contain a total of 1% steel fiber by volume. The workability tests of slump-flow, t500 and J-ring height difference were performed by the EFNARC. The samples were cured for 90 days and then, mechanical properties and electrical resistivity of samples were determined. Finally, the inclusion of steel fiber into SCC dropped the electrical resistivity and thus, increased its conductivity. In addition, hybrid fiber-reinforced SCC samples had the lowest electrical resistivity and highest conductivity and temperature rise. Also, 13 mm long micro steel fiber having high slenderness had a more positive effect on the electrical properties of concrete than 6 mm micro steel fiber.

Anahtar Kelimeler

• Macro and Micro Steel Fiber
• Hybrid Fiber Reinforced SCC
• Electrical Resistivity
• Conductivity
• Temperature Rise

KARMA ÇELİK LİFLİ KENDİLİĞİNDEN YERLEŞEN BETONUN ELEKTRİKSEL DİRENCİ

Öz

Beton yüksek basınç dayanımı yanı sıra çok düşük elektriksel iletkenliği sahiptir. Bu çalışmada kendiliğinden yerleşen betonun (KYB) elektriksel özdirenci, iletkenliği ve sıcaklık artışı üzerinde uzun ve kısa çelik liflerin etkisini, lif kombinasyonu (tek ve karma) ve kısa çelik liflerin boyuna (6 ve 13 mm) bağlı olarak belirlemek için dört adet karışım tasarlanmıştır. Bu karışımlar, lifsiz referans, sadece uzun tek lif takviyeli ve uzun lif ile iki farklı boya sahip kısa çelik lif içeren iki adet karma çelik lif takviyeli karışım olmak üzere dört farklı karışım tasarlanmıştır. Tüm çelik lif takviyeli KYB karışımları hacimce toplam %1 lif içermektedir. Karışımların belirlenmesinde EFNARC tarafından önerilen işlenebilirlik testleri (Çökme-yayılma, t500 ve J-halkası yükseklik farkı) dikkate alınmıştır. Karışımlara ait mekanik özellikler (basınç, yarmada çekme ve eğilme dayanımı) ile elektriksel özdirencin belirlenmesi için numuneler üretilmiş ve toplam 90 gün boyunca 23±2 0C’de su içerisinde kür edilmiştir. Sonuçta çelik lif takviyesinin betonun elektriksel özdirencini düşürdüğü ve dolayısıyla iletkenliğini artırdığı tespit edilmiştir. Bunun yanında karma lifli KYB numunelerinin en düşük elektriksel özdirenç ve en yüksek iletkenlik ile sıcaklık artışına sahip olduğu görülürken, narinliği yüksek olan 13 mm boyunda mikro çelik lifin betonun elektriksel özellikleri üzerinde 6 mm boyunda mikro çelik life göre daha olumlu etkiye sahip olduğu bulunmuştur.

Anahtar Kelimeler

• Makro ve Mikro Çelik Lif
• Karma Lifli KYB
• Elektriksel Özdirenç
• İletkenlik
• Sıcaklık Artışı

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