This paper investigated the suitability of the use of borrow pit sand locally known as Obimo sand in structural concrete. The physical properties of the unwashed Obimo sand (UOS) and the washed Obimo sand (WOS) were first investigated and compared to those of the conventional river sand (RS). Concrete cubes made from the three samples (UOS, WOS and RS) were crushed for their compressive strength. It was found out that the specimens fall within the acceptable limits of fine aggregates for structural concrete works given in both IS: 383 – 1970 and BS 882: 1973. The chemical composition obtained by elemental analysis using X-ray florescence spectrometry proved Obimo sand samples free of sulfate and saline contents. Also the concrete made from the WOS gave 6.5% more strength than that made from RS at 28 days age, while the UOS produced a concrete of slightly lower compressive strength. Specifically, the compressive strength ranged from 29.5 to 33 N/mm² for the alternative Obimo sand. Conclusively, a cost analysis carried out showed a reduction of 1.42% and 0.43% for the WOS and UOS concretes respectively when compared to that of RS.