DURABILITY of CONCRETE STRUCTURES PART 4. Prof. Dr. Halit YAZICI

Transcription

1 DURABILITY of CONCRETE STRUCTURES PART 4 Prof. Dr. Halit YAZICI

2 MARINE ENVIRONMENT PHYSICAL & MECHANICAL (freeze-thaw, waves, erosion, salt crystallization) CHEMICAL Sulfate (Mg 2 SO4) BIOLOGICAL (positive&negative effects) RF CORROSION

3 BIOLOGICAL FORMATIONS MARINE ENVIRONMENT Structures close to Shores WINDS CARRYING SALTY WATER COASTAL ATMOSPHERE CONCRETE STEEL COASTAL ATMOSPHERIC ZONE SPLASH ZONE RISING HIGH TIDAL ZONE Cracks Due to Steel Rusting Cracks Due to Freeze-Thaw, Wetting- Drying Erosion by waves (Sand, gravel, ice, etc. TIDAL ZONE SUB- SURFACE ZONE LOWERING SEA BASE LOW BELOW SEA LEVEL Decomposition of hydrated cement paste due to chemical processes Chemical effects: CO 2 effect Sulfate attack Mg ions exchange

4 SEA ENVIRONMENT SEA WATER: MOST IMPORTANT CHLORIDE SOURCE CORROSION : MAJOR RISK FACTOR OF COASTAL REINFORCED CONCRETE STRUCTURES WRONG DESIGN & PRODUCTION LEADS TO HEAVY DAMAGE IN A SHORT PERIOD (5-10 YEARS)

5 DETERIORATION RISKS Physical & Chemical Processes RISKS ACCORDING TO ZONES Coastal Atmospher e Splashing zone Tidal zone Submerge d zones Chloride Corrosion High High High Low Erosion (waves, floating materials) None High High Low Drying Wetting (Salt Crystallization) Low High High None Freeze - Thaw Low High High Low Chemical Reaction Low Low High High Biological Formations None High High High

6 SALINITY & ION CONCENTRATION OF TURKISH SEAS Sea Region Total Salinity (%) Mg +2 (mg/l) SO 4 +2 (mg/l) Cl - (mg/l) Na + (mg/l) Ca +2 (mg/l) Black sea Zonguldak Marmara Erdek Aegean Ayvalık Mediterranean Bodrum

7 SEA ENVIRONMENT

8 SEA ENVIRONMENT Excessive deterioration in wetting-drying zone

9 SEA ENVIRONMENT Excessive deterioration in wetting-drying zone YARIMCA PETKIM SEA PLATFORM (after earthquake)

10 SEA ENVIRONMENT

11 CLASSIFICATION OF ENVIRONMENTAL EXPOSURE TS EN206 Max. W/C PRECAUTIONS DUE TO CHLORIDE CORROSION (EXCEPT SEA WATER) XD1 XD2 XD Min. STRENGTH C30 C30 C35 Min. CEMENT DOSAGE (kg/m3) XD1 : HUMID, RARELY DRY (Splashing of water containing Chloride ions) XD2 : MODERATE HUMIDITY (Swimming pools, industrial water) XD3 : CONTINUOUSLY DRY-WET ENVIRONMENT (Bridges, Floors, car parking structures)

12 CLASSIFICATION OF ENVIRONMENTAL EXPOSURE TS EN206 Max. W/C PRECAUTIONS AGAINST SEA-WATER ATTACK XS1 XS2 XS Min. STRENGTH C30 C35 C35 Min. CEMENT DOSAGE (kg/m3) XS1 : INDIRECT CONTACT with SEA WATER (Structures close to shores XS2 : SUBMERGED STRUCTURES (Special zones of coastal structures) XS3 : COMPONENTS of COASTAL STRUCTURES EXPOSED TO TIDAL WAVES & SPLASHES

13 CLASSIFICATION OF ENVIRONMENTAL EXPOSURE

14

15

16 CLASSIFICATION OF ENVIRONMENTAL EXPOSURE TS EN206 Max. W/C Min. Strength (MPa) FREEZE-THAW XF1 XF2 EFFECT XF3 XF C30 C25 C30 C30 Min. CEMENT DOSAGE (kg/m 3 ) Min. Entrained Air (%) OTHER FREEZE-THAW RESISTANT AGGREGATE XF1 : MODERATELY WATER SATURATED (Vertical Concrete Surfaces) XF2 : MODERATELY WATER SATURATED, DE-ICING AGENTS (Vertical Concrete Surfaces) XF3 : HIGHLY WATER SATURATED (Horizontal Concrete Surfaces) XF4 : HIGHLY WATER SATURATED, DE-ICING AGENTS (Horizontal Concrete Surfaces)

17 CLASSIFICATION OF ENVIRONMENTAL EXPOSURE TS EN206 Max. W/C Min. Strength (MPa) AGGRESSIVE CHEMICAL ENVIRONMENT XA1 XA2 XA C30 C30 C35 Min. CEMENT DOSAGE (kg/m 3 ) OTHER SULFATE RESISTANT CEMENT XA1 : LOW AGGRESIVE CHEMICAL ATTACK XA2 : MODERATE AGGRESSIVE CHEMICAL ATTACK OR SEA WATER XA3 : EXCESSIVE AGGRESSIVE CHEMICAL ATTACK

18 CLASSIFICATION OF ENVIRONMENTAL EXPOSURE TS EN206 Max. W/C PRECAUTIONS DUE TO CHLORIDE CORROSION (EXCEPT SEA WATER) XD1 XD2 XD Min. STRENGTH C30 C30 C35 Min. CEMENT DOSAGE (kg/m3) XD1 : HUMID, RARELY DRY (Splashing of water containing Chloride ions) XD2 : MODERATE HUMIDITY (Swimming pools, industrial water) XD3 : CONTINUOUSLY DRY-WET ENVIRONMENT (Bridges, Floors, car parking structures)

19 GENERAL PRECAUTIONS

20 GENERAL PRECAUTIONS MILD ATTACK 1) TO PRODUCE IMPERMEABLE CONCRETE - Proper Gradation - Appropriate compaction - Low W/C ratio - Appropriate Curing - No Cracks - Structural Design - Water-Proofing admixtures - Stabilization of free Ca(OH) 2 with pozzolans - Impermeable concrete cover with sufficient thickness

21 CONCRETE COVER pren REINFORCED CONCRETE C min (mm) PRESTRESSE D CONCRETE C min (mm) NO RISK X0 CORROSION DUE TO CARBONATION XC1 XC2/XC3 XC4 CORROSION DUE TO CHLORIDES CORROSION DUE TO SEA WATER XD1/XD2/XD3 XS1/XS2/XS

22

23 CONCRETE COVER(mm) I II III IV V MAX W/C CONCRETE STRENGTH MIN CEMENT DOSAGE I : PROTECTED SURFACES AGAINST AGGRESSIVE ENVIRONMENT II : PROTECTED SURFACES EXCESSIVE RAIN & FROST DAMAGE, EXISTANCE OF CONDENSATION III : EXPOSED TO EXCESSIVE RAIN, DRYING & WETTING IV : SEA WATER, DE-ICING AGENT, FREEZE-THAWING V : ACIDIC WATER (ph 4.5), WEARING, EROSION

24 - Structural Design PRECAUTIONS H 2 O H 2 O H 2 O Isolation Protected Steel WRONG RIGHT PARTIALLY RIGHT H 2 O H 2 O H 2 O H 2 O WRONG RIGHT

25 PRECAUTIONS - Structural Design EVAPORATION PIPE RAIN WATER COLUMN ACCUMULATION OF AGGRESSIVE MATERIALS WRONG WRONG

26 PRECAUTIONS - Structural Design WRONG WRONG RIGHT RIGHT RIGHT

27 PRECAUTIONS - Structural Design Solution: Good drainage Good insulation Good Maintanence Severe Attack Insulated (de-icing agents) No-insulation Reinforced Concrete bridge

28 PRECAUTIONS - Structural Design Accumulation of rain water Splash WRONG RIGHT

29 PRECAUTIONS - Structural Design Rain water drainage Garden No-insulation Soil CAPILLARY SUCTION WATER FROM RAIN, PLANT WATERING, UNDERGROUND WATER

30 PRECAUTIONS - Structural Design INSTALLATION HOLES & PIPES WRONG WRONG DRAINAGE IS NEEDED RIGHT RISK OF: - BLOCKING - FREEZE-THAW - CHEMICAL REACTIONS - AGGRESSIVE MAT. (Cl- etc.) ACCUMULATION

31 PRECAUTIONS - Structural Design Air pollution, dust deposition Laminar Air stream Air pollution, dust deposition Heavy air stream

32 PRECAUTIONS - Structural Design Flow & washing out effect of rain Discoloring, deposition of dust

33 PRECAUTIONS - EXAMPLES OF POOR DESIGN

34 PRECAUTIONS - EXAMPLES OF POOR DESIGN

35 PRECAUTIONS - PROPER DESIGN

36 INCREASE IN DURABILITY PRECAUTIONS MODERATE EFFECT 2) (1) + USAGE OF SPECIAL CEMENTS - PC, EARLY HIGH STRENGTH - SLAG CEMENTS OR CEMENTS WITH LOW HYDRATION HEAT VALUES - TRASS CEMENTS - SULFATE RESISTANT CEMENTS - SUPER SULFATED CEMENTS - ALUMINA CEMENTS PROVIDED: OTHER FACTORS SAME! CURING PERIOD IS IMPORTANT!

37 BLENDED CEMENTS NATURAL POZZOLANS SLAGS FLY- ASHES ETC. LOW HYDRATION RATE CURING IS MORE IMPORTANT THAN PORTLAND CEMENTS PERMEABILITY INSUFFICIENT CURING PORTLAND CEMENT 0 GOOD CURING BLENDED CEMENT HIGH MINERAL ADMIXTURE %

38 PRECAUTIONS SEVERE ATTACK 3) (2) + INSULATION OF SURFACES

39 PRECAUTIONS SEVERE ATTACKS LIMITED PROTECTION RE-APPLICATION NECESSARY IN SHORT TIME PERIODS APPLICATION OF POLYMER BASED IMPERMEABILITY PAINTS

40 INSULATION APPLICATIONS CONTACT PLANE INSULATION MATERIAL CONCRETE STRUCTURE SEVERE ATTACK SURFACE TREATMENT HARDENING UP TO 6 mm DEPTH FOUNDATION CONCRETE (LEAN) WATER PROOF MEMBRANE SOIL UNDERGROUND WATER TO PROVIDE WATER PROOF BY PLASTIC BASED INSULATION MATERIALS CONCRETE SURFACES SHOULD BE CLEAN & DRY. GOOD BOND IS NECESSARY

41 DURABILITY of CONCRETE STRUCTURES PART 4 Prof. Dr. Halit YAZICI