Solving high sulfate content of sand used in concrete by magnetic water process

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The purpose of this research is to investigate the ability of magnetic water to solve the problem of high sulfate- (SO 3 %) by washing sand with magnetized water (intensity of 9000 Gauss). Three mixtures of ordinary concrete have been prepared for testing (compressive, flexural, and splitting tensile strength). Mix design was according to the ACI 211.1A with specified cylinder compressive strength (30 MPa) = (37.5 MPa) cub's compressive strength at the age of 28 days. Although mixing ratios were constant in all mixtures, the only difference was the percentage of fine aggregate (sand), which was equal to (0.2%) in the first mix and (2.1%) in the second mix. The Iraqi standard specification No.45 (1984) limited the upper limit of sulfate content in the sand not exceeded (0.5%). Solving these problems can be managed by washing process using a magnetic field device to treat sand before mixing been performed. The mechanical test results show a significant enhancement in the treated sand mix's fresh and hardened concrete properties compared with the control mix (containing untreated sand). The percentage decrease in (compressive, flexural, and splitting tensile strength), respectively, of the mixes containing high sulfate contents compared to the control mix, was up to [(1.27, 0.66, and 1.21), (5.83, 4.28, and 4.29), and (17.37, 8.37, and 11.58)] % at (7, 28, and 90 days). In contrast, the mixes containing treated sand have approximately strengths [(0.16, 0.13, and 0.80), (0.93, 0.28, and 0.66), and (0.15, 0.27, and 0.30) %] at (7, 28, and 90 days) to the control mix, which means the availability of the new technique of treated sand.