Recommended
More Related Content
What's hot
What's hot (20)
Viewers also liked
Viewers also liked (20)
Similar to CON 124 Session 3 - Concrete Durability
Similar to CON 124 Session 3 - Concrete Durability (20)
More from alpenaccedu
More from alpenaccedu (15)
Recently uploaded
Recently uploaded (20)
CON 124 Session 3 - Concrete Durability
- 1. CON 124 Basic Concrete Mix Design Proportioning Session 3 Concrete Durability
- 2. CON 124 - Session 3 This session will discuss Sulfate Attack Corrosion of Steel Mechanisms Recommendations and solutions
- 3. Sulfate Attack Mechanism Sulfate ions (SO4 -2) react with hydration products (calcium hydroxide and aluminate hydrates) Reaction products result in swelling (mechanism is uncertain) Swelling pressures destroy cement matrix Affected by Cement type Sulfate ion concentration in water or soil Permeability of concrete Presence water
- 4. External Sulfate Attack External to internal progression of deterioration
- 5. Mitigation of Sulfate Attack Use low w/c Use sulfate resistant cement (Type V) Use supplementary cementitious materials
- 6. Test method ASTM C1580 for determining water-soluble sulfates in soil
- 7. Table 4.2.1.b Exposure Category S – Sulfate Exposure Class Description Water-soluble sulfate (SO4) in soil, % by weight Sulfate (SO4) in water, ppm S0 NA < 0.10 < 150 S1 Moderate 0.10 to 0.20 150 to 1500 S2 Severe 0.20 to 2.00 1500 to 10,000 S3 Very Severe > 2.00 >10,000
- 8. Sulfate Class Maximum w/cm (Normal wt.), by mass Minimum f'c, MPa (psi) ASTM C150 ASTM C595 ASTM C1157 Other S0 — — — — — — S1 0.50 28 (4000) II IP(MS), IS(<70) (MS) MS — S2 0.45 31 (4500) V — HS No calcium chloride S3 0.45 31 (4500) V + pozz or slag — HS + pozz or slag No calcium chloride Table 4.3.1.b Exposure Category S – Sulfate Exposure Cement Types for Sulfate Resistance of various classes of sulfate attack, most severe sulfate resistance class is S3
- 9. Exposure Class Max. Expansion When Tested Using ASTM C1012 S1 0.10% at 6 months S2 0.05% at 6 months, or 0.10% at 12 months* S3 0.10% at 18 months * 12 month applies when 6 month is not met Table 4.5.1 Requirements for Establishing Suitability of Cementitious Materials Combinations When Exposed to Water-Soluble Sulfate Exposure Class and maximum expansion according to test method ASTM C1012
- 10. ASTM C1012 Standard Test Method ASTM C1012 for testing expansion due to sulfate solution.
- 11. ASTM C1012 • Evaluate sulfate resistance of different cementitious materials (cement, pozzolans, slag) • Use ASTM C109/C109M mortar mixture proportions to make 25 x 15 x 185 mm prisms • Immerse in sodium sulfate solution • Measure length change
- 12. Effect of Cement C3A on Sulfate Resistance 121110987654 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 C3A SulfateAttack4Month%Expansion R-Sq = 0.320 Y = 0.116075 - 3.71E -02X + 5.80E -03X **2
- 13. Long-term Sulfate Exposure Study Visual Rating Scale 1.1 2.5 5.0
- 14. Corrosion of Bridge Structures Fulton Road Bridge, Cleveland, Ohio Corrosion due to deicing salts used on roadway Wooden platform was built underneath concrete arch to protect patrons to the zoo from falling concrete Deck and columns need to be replaced because structurally deficient. Consulting Engineers trying to save arches and apply cathodic protection
- 15. Corrosion: How Big a Problem? “The average bridge deck located in a snow-belt State with black reinforcing steel and 40 mm (1.5 in.) of concrete cover has shown spalling in about 7 to 10 years after construction and has required construction and has required rehabilitation in about 20 years after construction.” Repair / Replacement Cost: ~ $ 20 billion & increasing
- 16. Marine Corrosion
- 17. Marine Corrosion – Replacement Bridge
- 18. Corrosion of Steel in Concrete High alkalinity of concrete promotes formation & stabilization of natural protective oxide layer at steel surface.
- 19. Corrosion of Steel in Concrete Electrochemical process that requires: Moisture & Oxygen Breakdown of Protective Oxide Layer (the Passive Layer)
- 20. 1/2 O2 + H2O + 2e- 2OH- Water Oxygen Chlorides, CO2 iron OH- Cathode Anode “ionic path” Electronic Path Fe 2e- + Fe2+ e- Corrosion Reaction - Necessary Factors Corrosion Reaction due to movement of ions
- 21. Corrosion of Steel in Concrete: Net Effect Corrosion by-product (rust) induces tensile stresses within matrix…..
- 22. Sources of Chloride De-icing Salts for Snow & Ice Removal Groundwater Brackish Water Seawater & Airborne Mixture design
- 23. Sources of Chloride De-icing Salts for Snow & Ice Removal Groundwater Brackish Water Seawater & Airborne Mixture design
- 24. Sources of Chloride De-icing Salts for Snow & Ice Removal Groundwater Brackish Water Seawater & Airborne Mixture design
- 25. Sources of Chloride De-icing Salts for Snow & Ice Removal Groundwater Brackish Water Seawater & Airborne Mixture design
- 26. Rule #1 for Corrosion Protection of Steel in Concrete Good Concreting Practices Good quality concrete Low water-cementitious materials ratio High-range water-reducing admixture Proper placement & consolidation Good Curing !!!
- 27. ACI 318 Classes for Corrosion Exposure Category Category Severity Class Condition C Corrosion Protection of Reinforcement Not Applicable C0 Concrete dry or protected from moisture Moderate C1 Concrete exposed to moisture but not to external sources of chlorides Severe C2 Concrete exposed to moisture and an external source of chlorides from deicing chemicals, salt, brackish water, seawater, or spray from these sources
- 28. ACI 318 Requirements for Concrete for Corrosion Exposure Category Exposure Class Max.w /cm Min.f’ c (psi) Additional Minimum Requirements Max Water-Soluble Chloride Ion (Cl-) Content in Concrete (percent by weight of cement) Related Provisions Reinforced Concrete Prestressed Concrete C0 n/a 2,500 1.00 0.06 None C1 n/a 2,500 0.30 0.06 C2 0.40 5,000 0.15 0.06 7.7.6, 18.16
- 29. Please return to Blackboard and watch the following videos: Video 1: Concrete Durability Freezing-Thawing Freethaw.mpg