Study of strength and ductility of galvanized iron wire reinforced concrete

Abstract

Fiber Reinforced Concrete is one of the most promising construction techniques of modern times and steel fiber is, by far, the front runner in the field of reinforcing fibers. A very recent investigation on the properties of locally available Galvanized Iron wire (GI wire) which is basically mild steel wire with a thin coating of Zinc has discovered that it has the potential to be a viable low-cost alternative of commercially available steel fibers. Therefore, a research has been conducted to study the performance of locally available GI wire fiber reinforced concrete (GWRC). This paper presents the findings of the research that made an effort to explore several basic characteristics of GWRC primarily related to strength, ductility and durability. The prime focus of the study was on the effect of fiber content on the foregoing properties of GWRC. Consequently, within the scope of the work, fiber dosage was varied within low volume content (1 to 3.5% by weight) while the concrete mix-design and fiber properties were kept unchanged. A wide variety of tests including compressive and splitting tensile strength, modulus of elasticity, and beam flexure test; Rapid Chloride Permeability Test (RCPT) and water absorption test (Sorptivity) were performed on suitable test specimens. Encouraging results were observed for compressive and tensile strengths and modulus of elasticity with significant increase in capacity. Durability test i.e. Sorptivity revealed that GI wire fiber inclusion has helped GWRC to reduce water absorption and thereby rendered GWRC more durable than normal concrete. RCPT proved indecisive in assessing durability of GWRC but the results can be considered for an indication to dispersion of fibers in the matrix. The major finding of the research was related to flexural capacity and ductility of GWRC. The beam flexure tests have shown a maximum of 30% increment of toughness; first-crack load increment up to 22%; and a maximum of 27% increase in the ultimate load with respect to the capacities of control beams (beams without GI wire fibers). Furthermore, cost analysis and comparison with steel fibers clearly depict that use of GI wire fiber instead of steel fiber comes with a substantial financial advantage from the perspectives of Bangladesh; a fact that makes the study even more worthwhile.