Structural Engineering

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Browsing Structural Engineering by Subject "Aggregate"

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    Effect of Fines Modulus of Crushed Sand on the Mechanical Properties of Concrete.
    (Addis Ababa University, 2021-07) Asres, Teshome; Girma, Zerayohannes
    This experimental study is to investigate the optimum fineness modulus range of crushed sand to be used in concrete mixes. For compressive strength determination of the hardened concrete, 45 concrete cubes and for flexural strength determination, 30 concrete simple beam specimen were prepared for testing. Five different fineness moduli and grading were tested 2.2, 2.5, 2.8, 3.0 and 3.2. All concrete cubes were left in curing until testing at the age of 7, 28 and 56 days respectively whereas the simple beam specimen were left in curing for the age of 7 and 28 days. Samples were loaded to failure and the average compressive and flexural strength was used for comparison purposes. To measure the workability of fresh concrete mixes, slump test had been used directly after mixing. Results confirmed that the optimum fineness modulus range for the crushed sand to be used as fine aggregate in the concrete mix to get maximum compressive and flexural strength is from 2.6 to 3.0. The slump test revealed an increment in the workability of fresh concrete with higher fineness modulus of crushed sand used in the concrete mix. The slump measure for the optimum fineness modulus is in the range of the recommended slump value which makes a workable mix. All finely crushed sand used in this research study checked to match the ASTM grading requirements for fine aggregate.