Post on 20-Aug-2018
SEWER SYSTEM
Hydrogen sulphide formationin oxygen-free surface
Escape of hydrogensulphide
Acidattack on concrete
Bacteriologicalformation of sulphuric acid in O2
containing environment at theconcrete surface
ACID ATTACK
ACID ATTACK
(Typical new and
undeteriorated condition of
sewer pipe)
(Concrete deterioration
of sewer pipe)
Effect of various acids on Concrete
Rate of
Attack
Type of acid
Inorganic Organic
Medium Phosphoric Tannic
Rapid
Hydrofloric,
Hydrochloric,
Nitric, Sulfiric
Asetic,
formic,
lactic
Slow Carbonic -
Negligible - Oxalic, Tartaric
ACID ATTACK
MASS LOSS, STRENGTH LOSS
INCREASE IN PERMEABILITY
SPECIMENS SUBJECTED TO 7% SULFURIC ACIDCONCENTRATIONS FOR 21 DAYS AFTER STANDARD CURING OF 28 DAYS
HNO3 HCl H2SO4 CH3COOH
ACID ATTACK
SURFACE VIEW OF SPECIMENS SUBJECTED TODIFFERENT ACID TYPES AND CONCENTRATIONS
pH meter
ACID ATTACK
Concrete silo
Agriculture Industry
grain silos
Organic acid
attack
humidity
Concrete pits for pickle production
ACID ATTACK
Phosphoric-Acid-Industry
ACID ATTACK
Concrete silo
Rubber- and Brick-Lining
for a concrete Reactor in
the Filtration unit
ACID ATTACK
A mineral processing plant’s
neutralization system pits and
chambers with a throughput of
500,000 litres per hour. The process is
continuous (24 hours a day). Tropical
location, the effluent is never below
45° C.
Concrete pit
ACID ATTACK
Concrete olive pool
Oleic acid attack
Triglyceride esters of oleic acid
compose the majority of olive
oil, although there may be less
than 2.0% as actual free acid in
the virgin olive oil, with higher
concentrations making the olive
oil inedible.
Attack by feed acids (aceticceticlacticlactic acidacid) ) and Urea
Concrete floors and columnsat animal barns
ACID ATTACK
A fertilizer basement in construction for a cow barn
ACID ATTACK
Corrosion of floodgate
due to acidic water
ACID ATTACK
Reinforced concrete floodgates
Precautions against acid attack
Epoxy impregnated
concrete floor or
direct epoxy coating
Coating of concrete
surface with polimer
or bituminous based
materials
ImpermeabilityImpermeability is not a is not a sufficientsufficientprecautionprecaution methodmethod againstagainst acidacid attackattack
SULFATE ATTACKDRY & SOLID SALTS ⇒ NOT DANGEROUS! HUMID ENVIRONMENT⇒DANGEROUS
Diffusion of sulfates into
concrete
Sulfate solutionfrom the
environment
Expansionreaction of
C3A
HydratedC3A
Crackformation
SOURCES OF SULFATE
SOIL (WHITE SALT RESIDUALS ON SURFACE; LAND DRY & WITHOUT TREES & PLANTS EXCEPT SOME BUSHES)
CEMENT (FROM GYPSUM CaSO4.2H2O, max. SO3 ≤≤≤≤ 3%)
SEA WATER, UNDERGROUND WATER
SULFATE ATTACK
General view of sulfate bearing soils
Mortar samples exposed to sulfate
BEFORESULFATE
EXPOSURE
AFTERSULFATEATTACK
SULFATE REACTIONS
IONS OF SO3> 200 (600 ppm) mg/l ⇒⇒⇒⇒ DANGEROUS
Sulfate ions
SO3- + Ca(OH)2 + H2O CaSO4.2H2O (124% Volume increase)
Gypsum
Na2SO4
Na2SO4.10H2O + Ca(OH)2 CaSO4.2H2O + 2NaOH + 8.H2O
Gypsum
MgSO4
MgSO4.7H2O + Ca(OH)2 CaSO4.2H2O+Mg(OH)2 + 5.H2O
Gypsum
REACTIONS WITH Ca(OH)2
3(CaSO4.2H2O)+3 CaO.Al2O3.12H2O+20H2O
3CaO.Al2O3.3 CaSO4.32H2O
Ettringite ( Candlot salt) 227% Volume increase
Na2SO4
2(3CaO.Al2O3.12H2O) + 3Na2SO4 . 10H2O
3CaO.AL2O3.3CaSO4.31H2O + 2Al(OH)3 + 6NaOH + 17H2O
MgSO4
REACTION WITH C3A
CaSO4.2H2O
3CaO.2SiO2.aq + MgSO4.7H2O
CaSO4.2H2O + Mg(OH)2 + SiO2.aq
Ettringite
Worst Effect: Attack to CSH besides C3A & Ca(OH)2
SULFATE REACTIONS
* WHITE STAINS
* CRACKS AT CORNERS & EDGES
* PEELING - DROPS
* SOFTENING - FRIABILITY
WATER MOVEMENT (WETTING&DRYINGCYCLES ACCELERATES THE REACTION)
SIGNS
DANGER LIMITS INWATER
INSOIL
TS3440 3000 ppmSO4-2
MILD 600 ppmSO4-2 2000 ppmSO4
-2
SEVERE 2000 ppmSO4-2 5000 ppmSO4
-2
SULFATE ATTACK
DANGER LIMITS ACCORDING TO ACI 201
Negligible 0.00 – 0.10 0 - 150
EffectSoluble (SO4
-2) %
IN SOIL IN WATER
SO4-2 mg/lt
Moderate 0.10 – 0.20 150 - 1500
Severe 0.20 – 2.00 1500 - 10000
Very severe over 2.00 over 10000
DAMAGED WATER CHANNEL
PIPES LEFT ON SOILS RICHWITH SULFATE
DAMAGED BRIDGE COLUMN
DAMAGED SIDEWALK
SULFATE TEST RESULTS(84 days of testing period)
Test specimen Control specimen
PREVENTATIVE MEASURES
IMPERMEABLE CONCRETE
USING CEMENT with LOW C3A CONTENT
STABILIZATION of LIME (Ca(OH)2) with POZZOLANS
CONCRETE MUST BE INSULATED if NECESSARY
C3A ≤ %8 CEMENT MODERATE RESISTANT to SULFATE
C3A ≤ %5 CEMENT HIGHLY RESISTANT to SULFATE
CLASSIFICATION OF ENVIRONMENTALEXPOSURE –TS EN206
AGGRESSIVECHEMICAL
ENVIRONMENT
XA1 XA2 XA3Max.
W/C 0.60 0.50 0.45
XA1 : LOW AGGRESIVE CHEMICAL ATTACK
Min. Strength
(MPa)C25/30 C35/45 C35/45
Min. CEMENT
DOSAGE (kg/m3)280 320 320
OTHER SULFATE RESISTANT CEMENT
XA2 :MODERATE AGGRESSIVE CHEMICAL ATTACK OR SEA WATER
XA3 : EXCESSIVE AGGRESSIVE CHEMICAL ATTACK
DEF (DELAYED ETTRINGITE FORMATION)
What is DEFWhat is DEF ( ( DelayedDelayed EttringiteEttringite FormationFormation ))??
Damage (expansion & cracking) of concrete due to the formation
of ettringite after the concrete has hardened
Damage due to DEF was first reported in heat-cured railway ties in
Germany in the early 1980’s Heinz et al, 1989
HUMIDENVIRONMENT
CEMENTTYPETEMPERATURE
- Wetting and drying cycles- Tightness problems,
- Massive structure- High cement quantity- Exothermic cement- Concreting in summer
- C3A > 7%- SO3 > 2,5%- Na2Oéq > 0,6%
TemperatureCement type
HumidEnvironment
DEFRisk
���� No characteristic properties of visual damages induced by DEF
���� The study of civil engineering structures shows that not onlyprecast concretes are concerned by DEF
���� There is a risk for large civil engineering structures
���� Nevertheless, numerous factors are implicated in the DEFmechanisms.
Those factors can by classified in 3 groups :
19
•Homogenious paste expansiontheory
•Crystal growth theory
(accumulation of ettringite crystals )
ETTRINGITE
Conversion to monosulfate
Sulfate adsorption by CSH
ettringite
time
DEF EXPANSION MECHANISMS
ettringiteettringite
monosulfoaluminatemonosulfoaluminate
DEF(DELAYED ETTRINGITE FORMATION)
PREVENTATION OF ETTRINGITE FORMATION IN EARLYPERIODS OF HYDRATION
CONTINOUS WETTING-DRYING IN OPEN ATMOSPHERE (HEAT)
LATE FORMATION OF ETTRINGITEC3A.CaSO4.32H2O
CRACKS
Delayed ettringite formation is a form of internalsulfate attack
SHANGHAI JINMAO BUILDING
Binanın yüksekliği: 440 m
Temel betonu sınıfı: C50
Temel yüksekliği: 4 m
Betonun yerleştirilmesinden 40 saat
sonra ölçülen sıcaklık : 97 °C
Beton sülfoaluminat bazlı
genleşen kimyasal katkı içeriyor
DEF Risk !!!
SHANGHAI JINMAO BUILDING
Binanın yüksekliği: 440 m
Temel betonu sınıfı: C50
Temel yüksekliği: 4 m
Betonun yerleştirilmesinden 40 saat
sonra ölçülen sıcaklık : 97 °C
SHANGHAI JINMAO BUILDING
Binanın yüksekliği: 440 m
Temel betonu sınıfı: C50
Temel yüksekliği: 4 m
Sulfoaluminate based chemical
admixture
40 hours Recorded concrete
temperature after casting : 97 °C
SHANGHAI JINMAO BUILDING
Height: 440 m
Foundation concrete class: C50
Height of foundation: 4 m
DEF (DELAYED ETTRINGITE FORMATION)
PREFABRICATED COLUMNS
TEXAS –prefabricated beam
DEF (DELAYED ETTRINGITE FORMATION)
BESIDES PREFABRICATION
MASS CONCRETE PRODUCTION ON HOT WEATHERS
IN FIRE
CharacteristicDEF Cracks
K9-E
Ettringite formation in void
90x 330x
1000x 3000x
Expansion for 502 days : % 0.86
%4.5 %4.5 SOSO33
5000 5000 cmcm22/g /g BlaineBlaine
Different forms of Ettringite
DU9-E
%4.5 %4.5 SOSO33
5000 5000 cmcm22/g /g BlaineBlaine
OOAlAl
SS
CaCa
CaCa
C3S + Water C-S-H + CH + HeatC3A + Water + Gypsum Ettringite + HeatC3A + Water + Ettringite Monosulfoaluminate
CaCa
SS
SiSi
AlAlMgMgOO CaCa
DEF (DELAYED ETTRINGITE FORMATION)
DEF (DELAYED ETTRENGITE FORMATION)
DEF (DELAYED ETTRENGITE FORMATION)
Cracks & Pores due toDEF
Pores filledwithettrengiteformation
DEF (DELAYED ETTRINGITE FORMATION)
Ettringite has - bydirected crystalgrowth - partlyfilled an air void
Air void completelyfilled with ettringite
crystals in a damaged pavement
concrete
DEFDEF
ASRASR
PREVENTIVE MEASURES AGAINST DEF
ÇİMENTO KLİNKERİNİN SÜLFAT İÇERİĞİ DÜŞÜK OLMALI
KÜR SICAKLIĞI ÇOK YÜKSEK OLMAMALI
DÜŞÜK HİDRATASYON ISILI ÇİMENTO KULLANILMALI
PUZOLANİK MADDE KULLANMAK SURETİYLE SÜLFAT MİKTARINI AZALTMAK
SU İLE TEMAS KESİLMELİ
HAVA SÜRÜKLEYİCİ KATKI KULLANIMI
DİĞER REAKSİYONLARDAN KAYNAKLANAN MİKROÇATLAKLARINOLUŞUMUNUN ENGELLENMESİ
ÇİMENTO KLİNKERİNİN SÜLFAT İÇERİĞİ DÜŞÜK OLMALI
SU İLE TEMAS KESİLMELİ
DİĞER REAKSİYONLARDAN KAYNAKLANAN MİKROÇATLAKLARINOLUŞUMUNUN ENGELLENMESİ
ÇİMENTO KLİNKERİNİN SÜLFAT İÇERİĞİ DÜŞÜK OLMALI
SU İLE TEMAS KESİLMELİ
DÜŞÜK HİDRATASYON ISILI ÇİMENTO KULLANILMALI
DİĞER REAKSİYONLARDAN KAYNAKLANAN MİKROÇATLAKLARINOLUŞUMUNUN ENGELLENMESİ
ÇİMENTO KLİNKERİNİN SÜLFAT İÇERİĞİ DÜŞÜK OLMALI
SU İLE TEMAS KESİLMELİ
PUZOLANİK MADDE KULLANMAK SURETİYLE SÜLFAT MİKTARINI AZALTMAK
DÜŞÜK HİDRATASYON ISILI ÇİMENTO KULLANILMALI
DİĞER REAKSİYONLARDAN KAYNAKLANAN MİKROÇATLAKLARINOLUŞUMUNUN ENGELLENMESİ
ÇİMENTO KLİNKERİNİN SÜLFAT İÇERİĞİ DÜŞÜK OLMALI
SU İLE TEMAS KESİLMELİ
KÜR SICAKLIĞI ÇOK YÜKSEK OLMAMALI
PUZOLANİK MADDE KULLANMAK SURETİYLE SÜLFAT MİKTARINI AZALTMAK
DÜŞÜK HİDRATASYON ISILI ÇİMENTO KULLANILMALI
DİĞER REAKSİYONLARDAN KAYNAKLANAN MİKROÇATLAKLARINOLUŞUMUNUN ENGELLENMESİ
ÇİMENTO KLİNKERİNİN SÜLFAT İÇERİĞİ DÜŞÜK OLMALI
SU İLE TEMAS KESİLMELİ
HAVA SÜRÜKLEYİCİ KATKI KULLANIMI
KÜR SICAKLIĞI ÇOK YÜKSEK OLMAMALI
PUZOLANİK MADDE KULLANMAK SURETİYLE SÜLFAT MİKTARINI AZALTMAK
DÜŞÜK HİDRATASYON ISILI ÇİMENTO KULLANILMALI
DİĞER REAKSİYONLARDAN KAYNAKLANAN MİKROÇATLAKLARINOLUŞUMUNUN ENGELLENMESİ
ÇİMENTO KLİNKERİNİN SÜLFAT İÇERİĞİ DÜŞÜK OLMALI
SU İLE TEMAS KESİLMELİ
USING AIR ENTRAINING AGENTS
PROPER CURING TEMPERATURES
USING POZZOLANIC MINERAL ADMIXTURES (REDUCINGSULFATE CONTENT)
CEMENT WITH LOW HEAT OF HYDRATION
PREVENTATION OF MICROCRACK FORMATIONS CAUSED BYOTHER REACTIONS
LOW SULFATE BEARING CEMENT
WATER INSULATION
THAUMASITE ATTACK (TSA)
-Sulfate or sulfide source
-Ground CaCO3 Carbonationor bicarbonates from groundwater
-water
-CSH
-Low tempeature (<15oC)
Bridge and tunnel structures
Scandinavian countries, England, North America, in particular cold climates
THAUMASITE ATTACK (TSA)
Deterioation of CSH structure
Loss of strength
Mushy like concrete
C-S-H + C-S-A-H + CaCO3
(CaSiO3.CaCO3.CaSO4.15H2O)
THAUMASITE FORMATION
Ferenc Puskas Stadium in Budapest (1954)
The planned limestone content of the cement amounted to 15%, but contaminated soft limestone was used
THAUMASITE
FERENC PUSKAS STADIUM
After World War II, in order to minimise the significant cement deficiency a clinker saving cement mix named Sigma Cement’ was produced to use in
construction of stadium in Hungary.
The average temperature in Hungary is about 70% of the year
longer than 15oC which is advantageous for thaumasite
formation!
EnvironmentalEnvironmental effectseffects, , corrosioncorrosion, , alsoalso thaumasitethaumasiteformationformation !!!!
cement produced has low strength and high fineness !
separation of the coarse fraction of the cement clinker is insufficient
the strength of the concretedecreased
gradually afterten year
construction
THAUMASITE
FERENC PUSKAS STADIUM
THAUMASITE
FERENC PUSKAS STADIUM
Specimens was exposed to highconcentration of MgSO4 solution
THAUMASITE FORMATION
LimestoneLimestone ratioratioincreasesincreases (%0(%0--40)40)
Tübitak 104I083
20oC MgSO4 (200 g/l) – 1 year
20oC Na2SO4 (200 g/l) – 1 year
Limestone increases
5oC Na2SO4 (200 g/l) – 1 year
5oC MgSO4 (200 g/l) – 1 year
C3A
%11.2
C3A
%4.6
C3A
%11.2
C3A
%4.6
C3A
%11.2
C3A
%4.6
C3A
%11.2
C3A
%4.6
Limestone increases
Limestone increases Limestone increases
C3A %4.6
5oC Na2SO4 – 1 year 5oC MgSO4 – 1 year
20oC Na2SO4 – 1 year 20oC MgSO4 – 1 year
C3A %11.2
5oC Na2SO4 – 1 year 5oC MgSO4 – 1 year
20oC MgSO4 - 1 year20oC Na2SO4 – 1 year
Limestonereplacement : %40
MgSO4 solution
(III-M-40)
THAUMASITETHAUMASITE
CaCa
CaCa
Mg Mg
SiSi S S
Al Al
PREVENTIVE MEASURES AGAINST
THAUMASITE FORMATION
FROM THE VIEW POINT OF STRENGTH AND DURABILITY, THE MAXIMUM LIMESTONE INCORPORATION AMOUNT SHOULD NOT EXCEED 10%, ESPECIALLY FOR THE STRUCTURES THAT ARE
CONSTRUCTED IN SULFATE BEARING SOILS AT COLD REGIONS.
LOW C3A CEMENT
MINERAL ADMIXTURES
REDUCE THE PERMEABILITY of CONCRETE
LOW SULFATE BEARING CEMENT
WATER PROOFING
ALKALIALKALI -- SILICASILICA REACTIONREACTION
ASRASR
ASR CAN BE EXPLAINED IN A TWO-STEP PROCESS
Diffusion of waterand alkalis into
concrete
Water and/or alkalisfrom the environment
(e.g. from de-icingsalts)
Crack formation(map cracking and
surface parallelcracking)
Diffusion of alkalis(e.g. from cement
and admixtures)
ASR gel; expansion
Reactive aggregate
1. ALKALI + SILICA ASR GEL2. ASR GEL + WATER EXPANSION
DETERIORATION OF CONCRETE
ASR REACTIVITY
3 REQUIREMENTS MUST BE MET !1) HIGH ALKALI OXIDE CONTENT
(Na2O + 0.658 K2O) > %0.6
2) REACTIVE SILICA(OPAL, TRIDYMITE, CRISTOBALITE, VOLCANICGLASS, RIYOLITE, ANDESITE & THEIR TUFFS)
GEL FORMATION (YEARS AFTER)(SODIUM + POTASSIUM + CALCIUM SILICATE)
SWELLING
MAP CRACKS
3) WATER