BCN 5905 –STRUCTURES I

1. BCN 5905 –STRUCTURES I Dr. Larry Muszynski RNK 327

2. Theme for the Class Steel rusts, Wood rots, but Concrete is forever!!!!!!!!!!! But unfortunately, we sometimes make concrete forms out of Timber

3. Class Structure • 30 - 75 minute periods. • 20 lectures, three exams, lab, two or three take home assignments and a Field trip?

4. Course Outline • Fundamentals and Properties of Concrete • Concrete Construction • Timber and Formwork

5. There is No such Animal as a Cement @$&!*^#% • Composition of Concrete • PC + Water + Aggregates (FA & CA) + Porosity • Heterogeneous and isotropic • Wood is homogeneous and non-isotropic • Steel is homogeneous and isotropic • 1 cu.ft. weighs 94 # • Properties of Fresh Concrete and Hardened Concrete

6. Fresh Properties • Slump • Temperature • Density & Yield • Air Content • Time of Setting

7. Hardened Properties • Strength • Air Content • Density, Absorption and Voids • Heavy ~ 150 pcf or about 2 tons pcy • Volume Change • Durability • Permeability

8. 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

9. Strength vs. w/c Ratio for PCC Strength, psi w/c ratio

10. 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

11. How about the Costs?

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 • Portland Cement • Limestone + Sand + Clay + Iron ore + heat(1500 C) = PC Clinker + Grinding = PC powder • Dry process and wet process • Hydraulic Cement – hardens in air and under water • Types I, II, III, IV and V • IA and IIA – blended with air-entraining agents • White Portland Cement

14. Blended Cements • Blended Cements • Type IP or P – Portland Pozzolan Cement • Moderate heat and moderate sulfate resistance • Class C Fly Ash – 15 to 40% • Class F Fly Ash – 15 to 25% (FDOT) • Type IS or S - Portland Blast Furnace Slag Cement • Low Heat (FDOT) • 25 – 70%

15. Other Cements • Masonry Cement (mortar) • Types N, S and M (See Table next slide) • Expansive Cements – Type K • High Early Strength Cements - RR • Calcium Sulfoaluminate – Rapid Set • Calcium Aluminate Cements- Cement Fondu • Magnesium Phosphate – SET-45 • Oil-Well Cements • Acid Resistant Cements • Silicate based • Sulfur

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

17. Aggregates • Coarse Aggregate • Retained on #4 Sieve • Igneous, Sedimentary and Metamorphic rock • Granite • Limestone • River gravel

18. CA continued • Maximum size from 6-in to 3/8-in • Max size governed by ACI code • Slab, form size and/or reinforcement • Graded down to #4 sieve according to ASTM C136 • Common gradations, 467, 57, 67 and 89 • 1-1/2 in max, 1-in max, ¾-in max, and 3/8-in max respectively

19. Aggregates • Fine Aggregate • Passing #4 Sieve ~ ¼-in. • Natural Siliceous and Crushed Limestone • Graded according to ASTM C33 • See next slide • Fineness modulus • Indication of the average particle size (2.0 to 3.0)

20. Fine Aggregate Grading Limits

21. Fine Aggregate Limits % Passing Sieve Size

22. 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

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

24. Chemical Admixtures • ASTM C-494 and 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

25. Air-Entraining Agents • ASTM C260 • 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 • 5% per percent of entrained air

26. Fibers • Steel • Individual and bundled • Glass – “alkali attack” • Synthetic – 1 to 1.5 lb per cu. yd. • polypropylene • nylon • Natural – “Egyptian pyramids” • Straw, bamboo, and wood

27. Concrete Building Systems • Beam and Girder Floor system • Composite construction with Steel Beams • One-way joist floor • Flat Slabs • Flat Plate slabs • Two-way joist floor • Precast and Prestressed concrete • Connections