Effect of the Presence of Ferric Iron in Water used for the Production of Concrete on Its Compressive Strength

Abstract

This study examined the effect of ferric iron inherent in mixing water on the compressive strength of concrete. Portland Limestone Cement was considered in the production of the 150mm concrete cube samples. Dirt free river sand and crushed stone with maximum size of 14mm was used as fine and coarse aggregate respectively. The water samples used for the study were sourced from the following locations as stated: Sample 1: Niger Delta University Portable water at Niger Delta University Campus, Wilberforce Island (labelled P1). Sample2: Raw water from borehole at Niger Delta University Campus, Wilberforce Island and allowed to oxidized about 3 hours. Sample 3: Raw water from borehole at Amassoma in southern Ijaw Local Area, Bayelsa state and allowed to oxidized for about 3 hours. Sample 4: Oxidized water from Ogobiri in Sagbama Local Area, Bayelsa state. Sample 5: Oxidized water from Azikoro in Yenagoa Local Area, Bayelsa state. 150mm x 150mm concrete cubes samples were prepared with the various water samples stated above. A mix ratio of 1:11/2:3 was used for this experimental study. The samples were cured in accordance with BS EN 12390-2. Compressive strength values were determined for all specimens by means of a compression testing machine. Samples were tested to failure at 7, 14, 21 and 28days. The concrete compressive strengths test results for 7, 14, 21, and 28 days for sample 1 was 24.22 N/mm2, 27.63 N/mm2, 34.04 N/mm2 and 34.59N/mm2. For sample 2 was 18.79 N/mm2, 23.55 N/mm2, 27.30 N/mm2 and 28.59N/mm2, for sample 3 was 21.12 N/mm2, 22.81 N/mm2, 25.19 N/mm2 and 26.56N/mm2, for sample 4 was 19.80N/mm2, 22.71N/mm2, 26.80N/mm2 and 27.40N/mm2and for sample was 20.89N/mm2, 21.88 N/mm2, 26.20 N/mm2 and 27.30N/mm2respectively. The test results, show a noticeable decrease in compressive strength of concrete cubes cast with water that contained ferric iron when compared with water free from ferric iron. It was concluded that Ferric iron as impurities in mixing water have significant effect on the strength of concrete.