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Silica Fume influence on RC Beams Behavior

United Arab Emirates University College of Engineering Department of Civil and Environmental Engineering Graduation Project II Second Semester 2007/2008. Silica Fume influence on RC Beams Behavior. Advisor: Dr. Ahmed Bushlaibi. Group members: Khamis Ahmed Khamis 199900588

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Silica Fume influence on RC Beams Behavior

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  1. United Arab Emirates UniversityCollege of EngineeringDepartment of Civil and Environmental EngineeringGraduation Project IISecond Semester 2007/2008 Silica Fume influence on RC Beams Behavior Advisor: Dr. Ahmed Bushlaibi Group members: Khamis Ahmed Khamis 199900588 Khalid HazaáMansour 200235841 Nasser Abdullah Alnaqbi 200212673 KhaledMoussalli200337587 1 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  2. contents • Introduction. • The split cylinder test. • The permeability test. • The bending test. • The flexural test. • Conclusion. 2 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  3. Introduction • Using silica fume as an enhancer for the concrete beams, slabs, columns and any other concrete structure. • Concrete is very good material in compression however it is very week in tension so that is way we use reinforcement in it. 3 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  4. Why Silica Fume ? Cement grains (left), silica fume particles (right) at the same magnification. The ACI 234R-96 report estimates that for a 15 percent silica fume replacement of cement, there are approximately 2,000,000 particles of silica fume for each grain of portland cement 4 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  5. Why Silica Fume ? • Change microstructure of the concrete • Physical aspect of silica fume : • Fills in the spaces between cement grains • Chemical contribution : • Cement releases calcium hydroxide. • Silica has very high silicon dioxide. • Calcium hydroxide will react with silicon dioxide to form calcium silicate hydrate. 5 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  6. Introduction • Concrete solidifies and hardens after mixing and placement due to a chemical process known as hydration. The water reacts with cement which bonds the other components together eventually creating a stone-like material. • Reinforcement is a good indication for failure because it gives us a warning. 6 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  7. Introduction • In GPI the concrete compression test was done. • Was that enough ??! • Four more test were done. • The split cylinder test. • The permeability test. • The bending test. • The flexural test. NO 7 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  8. The split cylinder test • The permeability test. • The bending test. • The flexural test. 8 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  9. Split Cylinder Test 9 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  10. Split cylinder test 10 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering • This test, often referred to as the split-cylinder test, indirectly measures the tensile strength of concrete by compressing a cylinder through a line load applied along its length.

  11. The testing machine 11 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering • This test can be completed in a standard concrete compression testing machine, with only one special requirement the hinged bearing that loads the specimen.

  12. The Experiment 12 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  13. Results The results above are in MPa 13 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  14. Results The results above are in MPa 14 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  15. Results The results above are in MPa 15 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  16. Results 16 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  17. The split cylinder test. • The permeability test. • The bending test. • The flexural test. 17 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  18. Permeability • Permeability describes the ease by which any species (i.e. liquid or gas) can pass through concrete. • Objective : Effect of silica fume in permeability of concrete on different percentage (0%,7.5%,10%,12.5%) 18 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  19. Inflow Concrete Specimen Flow path Water permeating through concrete Outflow Permeability • Most popular fluid is water • Most popular gas is O2 & CO2 19 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  20. Permeability test Shape: Cylinder v=πr2h R=15cm=0.15m r=7.5cm=0.075m h=2cm=0.02m V =(π )*(0.075)2*(0.02) =0.00035m3 V for 16 cylinder = (16)*(0.00035) =0.0056m3 R=15cm h=2cm 20 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  21. Calculation • Water content for 16 cylinder=1.12Kg/m3 • Cement content for 16 cylinder=3.3936kg Coarse Aggregate: For 16 cylinder = 5.1072 Kg Fine Aggregate: For 16 cylinder = 3.3432 Kg Super plasticizer: Sp=1.5 to 2 % of the total cement. SP= 1.65% * 3.3936 = 53 ml 21 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  22. Experiment 22 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  23. Curing • Water • 25 days • Oven • 3days 23 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  24. Transportation To protect sample against air moisture 24 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  25. Air permeability device 25 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  26. Line diagram for the oxygen permeability apparatus 26 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  27. The Permeability Cell 27 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  28. Permeability Coefficient (m/sec) Pressure head gradient Driving Force Pressure head (m) Volume Flow Rate (m3/sec) Flow Path i.e. specimen thickness (m) Cross Section (m2/sec) Permeability 28 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  29. 0% 7.5% 29 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  30. 10% 12.5% 30 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  31. The silica fume will effect on the permeability as shown in the chart, when the quantity of silica fume increase the permeability will decrease. 31 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  32. The split cylinder test. • The permeability test. • The bending test. • The flexural test. 32 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  33. Beam Design Design of RC Section Requires Determination of: • Concrete Dimensions • Beam width b • Depth of steel reinforcement d • Section height h = d + cover-to-center of steel • Area of steel reinforcement As • Ensure safety requirements (As) min ≤ As ≤ (As) max 33 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  34. Beam Design • Step 1: Assume Concrete Dimensions (Beam width & Section height) and Section Length • Beam width b = 100 mm • Section height h = 250 mm • Section Length L = 1.8 m 34 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  35. Beam Design Step 2: Estimate Beam Height According to ACI Deflection Requirements hmin = L/16 = 1800 / 16 = 113 mm hb = 250 mm > 113 mm 35 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  36. Beam Design Step 3: Assume bar size No. 10 For bar size No. 10, db = 9.5 mm 36 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  37. Beam Design Step 4: Calculate depth of steel reinforcement (d) Cover = concrete cover to steel center cc = clear concrete cover (20 mm for beams) ds = diameter of stirrups (bar size # 10) db = diameter of steel bar (bar size # 10) Hence, Cover = cc + ds + db/2 = 20 + 9.5 + 9.5/2 = 34 mm d = h - cover = 250 - 34 = 216 mm 37 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  38. Beam Design Step 5: Assume grade of a steel reinforcing bar & area of steel reinforcement As Grade 420 (i.e. fy = 420 MPa) is the most commonly used steel Use 2 bars No. 10 (As = 142 mm2) Step 6: Compute steel ratio (ρ) ρ = 142 / (100 * 216) = 0.00658 38 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  39. Beam Design Step 7: Ensure safety requirements (ρ) min ≤ ρ ≤ (ρ) max 39 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  40. 40 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  41. Beam Design Step 7: Ensure safety requirements (ρ) min ≤ ρ ≤ (ρ) max For fc' = 61.33 MPa 0.00466 ≤ ρ ≤ 0.03559 For fc' = 78.7 MPa 0.00528 ≤ ρ ≤ 0.04567 For fc' = 85.17 MPa 0.00549 ≤ ρ ≤ 0.04943 For fc' = 90 MPa 0.00565 ≤ ρ ≤ 0.05223 41 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  42. Experiment 42 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  43. Strain Gauges 43 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  44. Pouring the Concrete 44 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  45. The Smooth Concrete Surface 45 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  46. 46 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  47. 47 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  48. 48 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  49. The split cylinder test. • The permeability test. • The bending test. • The flexural test. 49 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

  50. What is Flexural Strength ? • One measure of the tensile strength. • Measure of an unreinforced concrete. • Loading beams with tow concentrated load. 50 Silica Fume influence on RC Beams Behavior Department of Civil and Environmental Engineering

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