Assessment of Mechanical properties of reinforcing steel used in construction works at F.C.T. Abuja

Abstract

the study assessed the mechanical properties, (yield stress, ultimate tensile stress and ductility) of reinforcing steel (ribbed bars) used in construction works in the federal capital Territory (FCT), Abuja, Nigeria wwith a view to ascertaining extent of conformity with (BS 4449) code requirements. The test samples obtained from four different companies (coded A,B,C,D) in the Federal capital and its adjoining states. The samples (10 mm, 12 mm, 16 mm and 20 mm) diameter bars were subjected to tensile strength test using a universal testing machine and a digital venier calliper. Test results showed that the yield stress of company (A) products are 320, 350, 405 and 410 N/mm2 for 10 mm, 12 mm, 16 mm and 20 mm bars which is less than BS 4449 specification of 460 N/mm2. The corresponding values for the ultimate tensile stress are 420, 440, 480 and 508 N/mm2 as against BS 449 value of 510 N/mm2 excerpt for 10 mm bars, the products of the company are less ductile since their ductilityis less than 12 % minimum specified by BS 4449. For company (B) products tested, only 16 mm and 20 mm bars conform to BS 4449 standards and the products are fairly ductile. For company (C), the yield stress of their tested products does not conform to BS 4449 standard. Though their ultimate tensile stress values conform to code specification, none met the code's minimum 12 % elongation indicating that their products are less ductile. For company (D) products, 10 mm and 12 mm bars fell short of BS 4449 specification in terms of yield and ultimate stress values but they are adequately ductile while for 16 mm and 20 mm bars that conform to code specifications , however, are less ductile. These results have far reaching consequences on construction works. In this light, it is strongly suggested that the composition of the elements and the type of alloy used in the production of steel in these companies be reviewed.