Effect of steel fibers on the strengths of lightweight concretes

SUMMARY Concretes, made up from lightweight aggregates, have superior properties such as lightness, economy, sound and thermal insulation, and resistance to earthquake and, resistance to fire. Furthermore it is known that addition of steel fibers into the concrete affects its properties affirmatively. When we take into account the rich lightweight aggregate resources in Turkey, investigating the effects of fiber addition on the properties of the lightweight concrete arises as a need. Because of the reasons mentioned above in this study, the dosage was taken constant at 300 kg/m3, natural aggregate was reduced 25, 50, 75, and 100 % by volume and then pumice from Erciş, Van, and from Pasinler, Erzurum was used instead of natural aggregate. 60 mm in length and 0.8 mm in diameter hooked-end steel fibers were added into the each mix in the ratio of 0, 0.5, 1.0, and 1.5 % by volume and concretes, which have 3 ± 1 cm constant slump, were produced. The properties of fresh and hardened concretes were determined and then these were compared with the control specimens. By this way investigating the effect of adding steel fibers on the concrete properties was aimed. The reason of preferring pumice as lightweight aggregate in this study is the use of pumice in East Anatolian Region widely especially in briquet production. The test results obtained in this study have indicated that the increase in steel fiber ratio in the mixes doesn't affect the unit weight significantly, but increases compressive strength, splitting - tensile strength, flexural strength, modulus of elasticity, and deformation capability. As a result by using steel fiber in lightweight aggregate concretes the properties, which are desirable in a structural member such as lightness, sound and thermal insulation, and strength can be obtained at the same time. Thus more economic solutions may be possible by reducing dead loads.