CONCRETE

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CE 599 SEMINAR PRESENTATION
CONCRETE IN MARINE ENVIRONMENT
Osmanuddin Adil Syed May 30th 2006
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• Content
• Introduction
• Marine Environment
• Deterioration of concrete structure
• Case Studies
• 
  
• Conclusions
• Ongoing research Work

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INTRODUCTION It is estimated that approx. 50
of the expenditure in the construction industry
are spent on repair, maintenance and remediation
of the existing structures. coastal and
offshore sea structures are exposed to the
simultaneous action of a number of physical and
chemical deterioration processes, which provide
an excellent opportunity to understand the
complexity of concrete durability problems in
practice. oceans make up 80 percent of the
surface of the earth therefore, a large number
of structures are exposed to seawater either
directly or indirectly.
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MARINE ENVIRONMENT
The prevailing environment in and in the vicinity
of an ocean or sea. Coastal areas, which can be
characterized to have a marine climate, reach
normally some 10km from the coastline, due to
wind-blown salt mist. However, at special
occasions, e.g. during severe storms, the area
influenced by the marine climate can be over 100
Km from the coastline.
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MARINE ENVIRONMENT (Contd.)
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MARINE ENVIRONMENT (Contd.)
Submerged Zone. The submerged zone is below the
surface of the water. The surface of a concrete
structure in this zone is constantly exposed to
water. Tidal zone. The Tidal zone is limited by
the extend of the tidal actions. The surface of
the concrete structure in this zone is cyclical
exposed to seawater.
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MARINE ENVIRONMENT (Contd.)
Splash zone. The splash zone is limited by the
extent of splash from breaking waves, above the
tidal zone. The surface of a concrete structure
in this zone is randomly exposed to
seawater. Atmospheric zone. The atmospheric
zone is limited by the extent of spray from
breaking waves, above the splash zone. The
surface of a concrete structure in this zone is
randomly exposed to spray from breaking waves.
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MARINE ENVIRONMENT (Contd.)
SUBMERGED ZONE Reinforced concrete structures
that are partially or fully submerged in seawater
are especially prone to reinforcing steel
corrosion due to a variety of reasons. These
include high chloride concentration levels from
the seawater wet/dry cycling of the concrete,
high moisture content and oxygen availability.
TIDAL ZONE The tidal zone is characterized by
periodical wetting and drying, and possible
freeze/thaw-actions. The surfaces in the tidal
zones, are mostly wet with a limited access of
oxygen. The extension of tidal zone varies
between 0 m up to 15 m.
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MARINE ENVIRONMENT (Contd.)
SPLASH ZONE The splash zone is characterized
by a randomly wetting and drying, depending on
the wave-actions. The extension of the splash
zone depends on the wave-heights and how well
protected the structure in question is. It is
also dependent on the variations in tidal water.

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MARINE ENVIRONMENT (Contd.)
The corrosion rate below water level is limited
by low oxygen availability, and conversely lower
chloride and moisture content limit the corrosion
rate above high tide. Corrosion is most severe
within the splash and tidal zones where alternate
wetting and drying result in high chloride and
oxygen content.
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DETERIORATION OF CONCRETE
From long-term studies of Portland cement mortars
and concretes exposed to seawater, the evidence
of magnesium ion attack is well established by
the presence of white deposits of Mg(OH)2, also
called brucite , and magnesium silicate hydrate.
In seawater, well-cured concretes containing
large amounts of slag or pozzolan in cement
usually outperform reference concrete containing
only Portland cement partly because the former
contain less uncombined calcium hydroxide after
curing.
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DETERIORATION OF CONCRETE (Contd.)
Since seawater analyses seldom include the
dissolved CO2 content, the potential for loss of
concrete mass by leaching away of calcium from
hydrated cement paste due to carbonic acid attack
is often overlooked. According to Feld in 1955,
after 21 years of use, the concrete piles and
pile caps of the James River Bridge at Newport
News, Virginia, required a 1.4 million repair
and replacement job which involved 70 percent of
the 2500 piles.
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DETERIORATION OF CONCRETE (Contd.)
Similarly, 750 precast concrete piles driven in
1932 near Ocean City, New Jersey had to be
repaired in 1957 after 25 years of service some
of the piles had been reduced from the original
550 mm diameter to 300 mm. In both cases, the
loss of material was associated with higher than
normal concentrations of dissolved CO2 present in
the seawater.
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DETERIORATION OF CONCRETE (Contd.)
The presence of thaumasite (calcium
silicocarbonate), hydrocalumite (calcium
carboaluminate hydrate), and aragonite (calcium
carbonate) have been reported in cement pastes
derived from deteriorated concretes exposed to
seawater for long periods.
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DETERIORATION OF CONCRETE (Contd.)
ACTION OF CO2 a) Ca(OH)2 CO2 H2O
? CaCO3 2 H2O
Precipitate
? ?
aragonite Calcite
COATING
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DETERIORATION OF CONCRETE (Contd.)
ACTION OF SULFATE MgSO4 b) Mg2 ? Ca2
substitution MgSO4Ca(OH)2 ? CaSO4
Mg(OH)2
? ?
? soluble
Solid secondary Precipitate
LEACHING gypsum
COATING
EXPANSION c) Action of secondary gypsum
CaSO4 C3A 32 H2O ?
C3A.3CaSO4.32 H2O
ettringite

EXPANSION
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DETERIORATION OF CONCRETE (Contd.)
ACTION OF CHLORIDE MgCl2 d) Mg2 ? Ca2
substitution MgCl2 Ca(OH)2 ?
CaCl2 Mg(OH)2
Soluble
precipitate
LEACHING COATING e) Action
of CaCl2 CaCl2 C3A 10H2O ?
C3A.CaCl2.10H2O
Chloro aluminate

EXPANSION

? SO3
C3A.3CaSO4.32H2O
ettringite

EXPANSION

?CO2 SiO2
CaCO3.CaSO4.CaSiO3.15H2O

thaumasite
EXPANSION
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STUDIES
A case study by Di Malo, on the chloride profiles
indicates a greater damage due to corrosion was
detected in the surface facing the sea and in
lower sections of the structure, particularly
ground floor columns.
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STUDIES (Contd.)
Use of Admixtures According to Fookes.P.G.
Sulfate resisting cements suffer less chemical
decomposition in sea water than OPC, but it is
not fully understood which type of cement is most
effective in controlling the migration of
chloride ions. Calculated addition of the
pozzolan can improve the durability of concrete
by removing a part of free lime, reducing
permeability and at the same time protecting the
reinforcement. Many authors have shown that Blast
furnace slag cement, especially when well cured,
resists the action of seawater fairly well.
However, this BFS cannot be always the governing
cement.
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STUDIES (Contd.)
Al- amoudi, KFUPM , conducted a study to
investigate the durability of two concrete (type
1 type 5) and three blended cements prepared by
Fly ash, Silica Fume and Blast furnace slag, in
marine environment. The specimens were exposed to
seawater for a period of 2 years. The data on
reinforcement corrosion confirmed the superior
performance of silica fume cements in sea water,
followed by BFS and fly ash Cements. The
corrosion resistance of Type 1 cement was
marginally better than that of Type 5 cement.
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CONCLUSIONS
The marine environments can be distinguished as
1) The submerged zone 2) The tidal zone 3)
The Splash Zone, and 4) The atmospheric zone
Investigations of reinforced concrete structure
have shown that, generally, concrete fully
immersed in seawater suffered only a little or no
deterioration concrete exposed to salts in air
or water spray suffered some deterioration,
especially when permeable and concrete subject
to tidal action suffered the most.
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CONCLUSIONS (Contd.)
The presence of thaumasite, hydrocalumite and
aragonite have been reported in cement pastes
derived from deteriorated concretes exposed to
seawater for long periods. Major deterioration
was observed in the samples having greater
thaumisite.
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REFRENCES
Long A.E., H., G.D. Montgomery, F.R. (2001).
"Why assess the properties of near-surface
concrete?" Construction and Building materials,
v.15 pp.65-79. Mehta.P.K., Monteiro.P.J.M
(October 20, 2001). A textbook on
Concrete-Microstructure, Properties and
Materials, Prentice-Hall, New Jersey. Fookes, P.
G., Barr, J.M., Simm, J.D. (1986). Marine
Concrete performance in different climatic
environments. International conference on
concrete society, London, Concrete in Marine
Environment. Gjorv. O.E., J. (1971). "Concrete in
Marine environment." ACI, v.68
pp.67-70. Al-Amoudi.O.S.B. (2002). "Durability
of Plain and blended cements in marine
environments. Advances in cement Research,
v.14.03 pp.89-100. Landau. A (1987). A system
of inhibiting steel corrosion in concrete. 23rd
Technical conference, New Zealand, New Zealand
concrete society. Virmani, Y. P., Jones,W.R.,
Jones,D.H. (1984). Public Roads, v.84.03,
pp.96. Di Malo. A.A., L. J. L. L. P. T.
"Chloride profiles and diffusion coefficients in
structures located in marine environments."
Structural concrete, v.5.01 pp.23-26.
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Jubail Research Center
A field exposure station has been established at
Khaleej Mardomah in Al-Jubail Industrial City.
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Mix No. Additives kg Mix No. Additives kg
M1 - M8 20 FA
M2 - M9 -
M3 - M10 Coal tar epoxy
M4 8 SF w/c 0.3 M11 SIKA 901
M5 - M12 SIKA 903
M6 0.2 PP Fibers M15 10 Super-Pozz
M7 8 SF M17 30 FA
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Property Zone Ranking per property Ranking per property Ranking per property Ranking per property Ranking per property Ranking per property Ranking per property Ranking per property Ranking per property Ranking per property Ranking per property Ranking per property Ranking per property Ranking per property
Property Zone M4 M7 M15 M17 M8 M1 M10 M5 M3 M2 M11 M9 M6 M12
Compressive Strength Tidal 5 4 3 6 8 2 9 1 11 12 7 10 14 13
Compressive Strength Below 2 1 5 7 8 4 14 3 6 9 12 13 11 10
Compressive Strength Above 1 2 4 8 7 3 14 5 6 9 11 10 13 12
Chloride Permeability Tidal 3 4 1 2 5 6 9 7 11 12 8 13 10 14
Chloride Permeability Below 3 1 4 6 2 5 12 8 7 10 13 11 9 14
Chloride Permeability Above 8 1 2 5 3 7 11 9 4 12 6 10 14 13
Electrical Resistivity Tidal 5 2 7 8 4 3 6 10 1 12 9 11 14 13
Electrical Resistivity Below 10 7 4 5 9 6 1 2 14 8 11 3 13 12
Electrical Resistivity Above 13 3 6 5 4 2 1 14 10 11 9 8 12 7
Water Absorptoin Tidal 2 8 7 9 3 1 12 5 6 4 11 14 13 10
Water Absorptoin Below 3 6 9 10 4 2 1 5 8 7 13 14 12 11
Water Absorptoin Above 3 11 13 14 9 2 2 8 5 4 7 12 10 6
Water Perbility Tidal 4 11 2 3 14 13 1 5 12 7 6 8 10 9
Water Perbility Below 3 5 10 8 6 11 1 4 9 7 13 12 14 2
Water Perbility Above 5 2 4 3 7 6 1 9 11 12 8 10 13 14
Total Total 68 70 81 86 93 99 100 105 136 145 148 161 168 179
Overall Ranking Overall Ranking 1 2 3 4 5 6 7 8 9 10 11 12 13 14
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