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Fundamentals of Concrete

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Fundamentals of Concrete

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    1. Fundamentals of Concrete

    3. Fresh Properties - ASTM Slump Temperature Density & Yield Air Content Time of Setting

    6. Hardened Properties - ASTM Strength Air Content Density, Absorption and Voids Volume Change Durability Permeability

    8. Durability Freeze – Thaw Chloride-Ion Alkali-Aggregate Sulfate

    9. How does Concrete Get Its Strength PC + water = hydration reaction > GLUE + Heat Cementitious material literally glues all of the inert (non-reactive) aggregates together to produce a solid load bearing mass that we call PCC Strength is inversely proportional to the water-to-cement ratio

    10. Strength vs. w/c Ratio for PCC

    11. What’s Important Good quality materials PC, water, coarse aggregate, and fine aggregate Proper Proportioning of the Materials Proper Mixing Placing and Finishing Proper Curing QC Testing

    12. Other Types of Concrete Lightweight Concrete Structural and Non-structural (120 – 50 pcf) High Density Concrete (400 pcf) Mass Concrete Pre-placed Concrete No Slump Concrete Roller-Compacted Concrete Shotcrete (Wet and Dry)

    13. PC does NOT come from Portland Oregon History Portland Cement Limestone + Sand + Clay + Iron ore + heat(1500 C) = PC Clinker + Grinding = PC powder Dry process and wet process (p. 22 and 23) Hydraulic Cement – hardens in air and under water Types I, II, III, IV and V What does 1 bag of PC weigh?

    17. General Types of Cement Type I – General Purpose Type II – Moderate Heat, Moderate Sulfate Resistance Type III – High Early Strength Type IV – Very Low Heat Type V – High Sulfate Resistance

    18. Blended Cements Type IP or P – Portland Pozzolan Cement Moderate heat and moderate sulfate resistance Class F Fly Ash – 15 to 25% (FDOT – 18-22%) High Early Strength Class C Fly Ash – 15 to 40%

    20. Blended Cements Type IS or S - Portland Blast Furnace Slag Cement Low Heat (FDOT) 25 – 70%

    21. Other Types of Cement High Early Strength Cements – RR Magnesium Phosphate – SET-45 Calcium Aluminate Cements- Cement Fondu Calcium Sulfoaluminate – Rapid Set

    22. RR Mixing Equipment

    24. Mixing Water Potable ie. Water suitable for drinking Chloride < 0.05% Sulfate < 0.08% Organic salts < 0.05% sugar

    25. Strength vs. w/c Ratio for PCC

    27. Aggregates Coarse Aggregate Retained on #4 Sieve 0.187 in (3/16”) or 4.76 mm Igneous, Sedimentary and Metamorphic rock Granite Limestone River gravel

    28. CA continued Maximum size from 6-in to 3/8-in Max size governed by ACI code Graded down to #4 sieve according to ASTM C136 Standard Specification for Concrete Aggregates ASTM C33 (Table 5.5, p. 84-5). Common gradations, #467, #57, #67 and #8 (#89-FL) 1-1/2 in max, 1-in max, ž-in max, and 3/8-in max respectively Aggregate Testing according ASTM Standards TABLE 5.2 (Page 81), Table 5.6 and 5.7, (page. 92). Dry-Rodded Unit Weight test of coarse aggregate ASTM C29

    29. Dry-Rodded Unit Weight of CA Test

    30. Aggregates Fine Aggregate Passing #4 Sieve <3/16 - in. Natural Siliceous and Crushed Limestone Fines Aggregate Testing according to ASTM TABLE 5.2 (Page 81) Graded according to ASTM C33 OR FDOT 902 Table 5.3 See next slide Fineness modulus Indication of the average particle size (2.0 to 3.0)

    32. Fine Aggregate Grading Limits (ASTM and FDOT)

    34. Sieve Analysis Test

    35. Aggregate Testing AASHTO Standards T11, Materials Finer Than 75 ľm (No. 200) Sieve in Mineral Aggregates by Washing T19/ T 19M-00, Bulk Density (“Unit Weight”) and voids in Aggregate T21, Organic Impurities in Fine Aggregates for Concrete T27, Sieve analysis of Fine and Coarse Aggregates T84, Specific Gravity and Absorption of Fine Aggregate T85, Specific Gravity and Absorption of Coarse Aggregate T96, Resistance to Degradation of Small-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine ASTM Standards ASTM D4791, Standard Test Method for Flat Particles, Elongated Particles, or Flat and Elongated Particles in Coarse Aggregate ASTM D5821, Standard Test Method for Determining the Percentage of Fractured Particles in Coarse Aggregate

    37. Fineness Modulus Calculation

    39. Lab 1 Information Handouts Unit Weight of CA Gradation and FM of Fine Aggregate NO OPEN TOE SHOES

    40. Unit Weight of CA – ASTM C29 Volume of Measure Unit Weight – loose condition Unit Weight – compacted condition

    41. Gradation and FM of Fine Aggregate – ASTM C136

    44. Fineness Modulus Calculation

    45. Fine Aggregate Grading Limits (ASTM and FDOT)

    46. Recycled Concrete Aggregate Old concrete that has been removed and crushed to produce aggregate. Coarse aggregate in new concrete Fine aggregate in new concrete Best combination is CA with natural fine aggregate Good strength Drying shrinkage problem Base-coarse replacement for natural limestone Pervious concrete pavement using recycled concrete as coarse aggregate.

    47. Pervious Concrete

    54. Mineral Admixtures Pozzolanic (cement replacement) Class F Fly ash – 15 to 25% bwc Class C Fly ash –15 to 40% bwc Blast Furnace Slag (cement replacement) 25 to 70% bwc Silica Fume (cement addition) 6 to 12% bwc

    55. Chemical Admixtures – ASTM C-494 (Ch. 6) Table 6-1 Water Reducing – Type A Set Retarding – Type B Set Accelerating – Type C Water Reducer-Set Retarding – Type D Water Reducer-Accelerating – Type E High Range Water Reducers – Type F HR Water Reducer-Set Retarding -Type G

    57. Air-Entraining Agents – ASTM C260 (Ch. 8) Admix that produces stable bubble system Liquid and solid Low dosage rates relative to other chemical admixtures (0.005 to 0.05% bwc). Increase in durability – @freeze/thaw Reduces compressive strength 3-5% per percent of entrained air

    60. Fibers (see Table 7-1) Natural – “Egyptian pyramids” Straw, bamboo, and wood Glass – “alkali attack” Steel Fibers Synthetic – 1 to 1.5 lb per cu. yd. polypropylene nylon

    61. Ethics and Safety PC – The most expensive component of the mix Don’t get shorted on this material Life Cycle Costs vs. Material Costs PCC inherently a safe material considering: Highly alkaline Eye protection Skin irritations

    62. How about the Costs?

    63. ASTM C143 Size of slump cone Time to complete test Sampling – 5 min Start of test – 2.5 min Read to nearest ź in Rodding – 25 times per layer = 75 times

    64. ASTM C138 Bucket size Unit wt calc. Yield calc Rodding procedure

    65. ASTM C231 Air content by pressure method Rodding procedure Procedure Aggregate correction factor results

    66. ASTM C173 Air content – volumetric Rodding technique Method results

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