GRADING OF FINE CRUSHED STONE AND ITS EFFECT ON CONCRETE PROPERTIES USED IN THE UNITED ARAB EMIRATES

This experimental study is a modification on a previous study to investigate the optimum grading of fine crushed stone to be used in concrete mixes. For compressive strength determination of the hardened concrete, 45 concrete cubes were prepared for testing. Five different Fineness Moduli and grading were tested 2.4, 2.6, 2.75, 2.92 and 3. All cubes were left in curing until testing at the age of 3, 7 and 28 days respectively. Samples were loaded to failure and the average compressive strength was used for comparison purposes. To measure the workability of fresh concrete mixes, flow table test had been used directly after mixing and the average of the maximum concrete spread parallel to the two edges of the table was recorded. Results confirmed that the optimum Fineness Modulus for the crushed stone to be used as fine aggregate in the concrete mix to get maximum compressive strength is 2.78. The flow table tests revealed an increment in the workability of fresh concrete with higher Fineness Modulus of fine crushed stone used in the concrete mix. The workability of the optimum Fineness Modulus, 2.78, was estimated to be approximately 415 mm which is a mix with considerable workability. All finely graded crushed stone used in this research study checked to match the ASTM grading requirements for fine aggregate.