ISEC 08


BOND BEHAVIOR OF LIGHTWEIGHT FIBER REINFORCED CONCRETE

KLAUS HOLSCHEMACHER, AHSAN ALI, SHAHID IQBAL


Abstract

In construction industry lightweight concrete and fiber reinforced concrete are being used for many years. The former is known for brittle nature, light in weight and low thermal conductivity properties. It also offers better workability when compared to the normal weight concrete for the same slump value. These properties are however affected by addition of discrete fibers. Among the affected properties is also the bond between steel and concrete surrounding it. The integrity of a reinforced concrete member is not ensured in the absence of adequate bond. Due to limited literature on the subject matter, an experimental program was carried out to understand the bond behavior in lightweight concrete after fiber inclusion. For the purpose modified pull-out specimens made of Lightweight Fiber Reinforced Concrete (LWFC) were tested. Hooked end steel fibers having length 35 mm and diameter 0.5 mm (l/d = 0.7) were incorporated in dosages of 0, 20, and 40 kg/m3. Besides pull-out specimens, testes were also carried out for fresh and hardened properties of LWFC. Tests results indicate higher pull-out loads for higher fiber contents. The average increase in ultimate bond strength was observed at 28% and 2% for 40 kg/m3 and 20 kg/m3 fiber contents respectively. The fresh concrete density, compressive strength of mixes reduced and air-content values increased with increase in fiber content.

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