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Deterioration of reinforced concrete in sewer
environments
A. K. Parande MTech, P. L. Ramsamy BTech, S. Ethirajan BTech, C. R. K. Rao PhD and N. Palanisamy PhD
Millions of dollars are being spent worldwide on the repair
and maintenance of sewer systems and wastewater
treatment plants. Microbially-induced corrosion causes
damage via micro-organisms. Deterioration is caused by
acid excretion which etches the surface of concrete,
penetrating the mortar surface, especially in sewer
systems. The mechanisms of concrete and
reinforcement deterioration in sewer environments and
microbially-induced corrosion is discussed in detail in this
paper. A comprehensive review is given of the role of
hydrogen sulphide and micro-organisms in the
deterioration of concrete in sewer environments and of
repair and rehabilitation measures, including the following
preventative measures: (a) modification of the materials
used in construction of sewer pipes; (b) coatings; (c) sewer
treatments. A complete review of the microbial
deterioration of concrete and its remedies is also included.
1. INTRODUCTION
Nowadays, concrete is the material that is being used for
pipelines for sewage waste disposal. The corrosion of concrete in
sewers poses a major problem in the modern world. Millions of
dollars are being spent on the repair and maintenance of sewer
pipelines and wastewater treatment plants. The presence of
various bacteria—such as the sulphur-reducing and the
proteolytic bacteria in the sewer—together with animal and plant
wastes is the main reason for the corrosion of concrete.
Most of these sewer pipelines are concrete that has been either
cast in place or precast. Brick manholes have been replaced over
the years because of concerns about infiltration and a realisation
that the mortar holding the bricks together is subjected to
corrosion. Prefabricated plastic manholes have been introduced,
but in some cases they are difficult to install; for example, in high
groundwater areas they tend to float out of the hole if proper
ballast or anchorage has not been applied. Care should be taken
in these areas, and also with regard to water passing through
these manholes, therefore all the joints should be properly sealed
with rubber gaskets.
There are two major causes of internal corrosion in a sanitary
sewer. The first is conventional acid attack caused by low pH
industrial waste discharged directly into the sewer system. The
second cause is grouped together as sulphide corrosion, hydrogen
sulphide (H
2
S) corrosion or sulphide attack. These types are easy
to identify. Sulphide corrosion occurs above the sewage surface
while low pH sewage will cause corrosion below the waterline.
1
Sulphate attack, sometimes confused with sulphide corrosion,
occurs when soils with high sulphate levels contact the concrete
pipe structure and the deterioration is external. Sulphate attack
does not occur inside the sewer structure or pipe. Sulphide
corrosion starts when sulphate in the sewage is converted to
sulphur. The most corrosive agent that leads to the rapid
deterioration of concrete pipelines in sewers is (H
2
S), which also
attacks concrete floors in barn buildings housing animals. H
2
S
also attacks the concrete in sewer and wastewater treatment
plants. The aerobic bacteria present oxidise the H
2
S dissolved in
the moisture to sulphuric acid (H
2
SO
4
). The H
2
S dissolves in
moisture films on the exposed concrete surfaces where it
undergoes oxidation by aerobic bacteria to H
2
SO
4
, commonly
referred to as biogenic sulphuric acid (BSA), which attacks the
concrete surface.
2
The corrosion process is caused by the reaction
of the BSA with the cementitious material of the concrete,
which leads to eventual structural failure. This step is
characterised by the production of a corroding layer on the
surface of the concrete. This layer consists of gypsum (CaSO
4
of
various hydration states) and moisture. The thickness of this
layer expands into the concrete as more and more acid is
produced to react with the concrete. The formation of ettringite
(3CaO .Al
2
O
3
.CaSO
4
.12H
2
O or 3CaO .Al
2
O
3
.3CaSO
4
.31H
2
O)
during the acid reaction process is another facet of the problem.
Ettringite is expansive and causes internal cracking and pitting,
which provides a larger surface area for the chemical reaction to
occur. This will also provide further sites of penetration of the
acid into the concrete. The conversion of the concrete to gypsum
and ettringite weakens the structural integrity of the concrete
pipe. This reduces the load-bearing capacity of the concrete and
can result in the eventual collapse of the sewer.
The action of anaerobic proteolytic bacteria in sulphur-
containing organic compounds results in the H
2
S. Design of
sewer structures is an important parameter. In general, any
configuration that results in significant hydraulic energy loss will
accelerate corrosion and may also induce serious corrosion of the
downstream pipe. The concrete can be prevented by two
subgroups: prevention of corrosion of concrete and corrosion
A. K. Parande
Scientist, Central
Electrochemical Research
Institute, Karaikudi,
Tamilnadu, India
P. L. Ramsamy
Student, Central
Electrochemical Research
Institute, Karaikudi,
Tamilnadu, India
S. Ethirajan
Student, Central
Electrochemical Research
Institute, Karaikudi,
Tamilnadu, India
C. R. K. Rao
Scientist, Central
Electrochemical Research
Institute, Karaikudi,
Tamilnadu, India
N. Palanisamy
Scientist, Central
Electrochemical Research
Institute, Karaikudi,
Tamilnadu, India
Proceedings of the Institution of
Civil Engineers
Municipal Engineer 159
March 2006 Issue ME1
Pages 11–20
Paper 14373
Received 11/08/2005
Accepted 14/12/2005
Keywords:
concrete technology &
manufacture/corrosion/sewers &
drains
Municipal Engineer 159 Issue ME1 Deterioration of reinforced concrete in sewer environments Parande et al. 11
of reinforcement. The latter subgroup has the following
characteristics
(a) altering the material used for the pipelines
(b) providing corrosion-resistant coatings
(c) providing cathodic protection
(d) modifying the engineering aspects of the structure.
This paper discusses the mechanisms involved by H
2
S in sewers
that cause the deterioration of concrete, together with subsequent
control measures.
2. DETERIORATION OF CONCRETE: CAUSES AND
DETERMINATION
A general consensus has been that H
2
S is the most corrosive
agent that leads to the rapid deterioration of concrete pipelines in
sewers. The aerobic bacteria present oxidise the H
2
S, which is
dissolved in the moisture, to produce H
2
SO
4
.
2
At normal domestic
sewage pH levels, from one-quarter to one-third of the dissolved
sulphide exists as molecular H
2
S, which is released to the air
and deposited on the moist structure wall. Bacteria on the wall
convert the H
2
StoH
2
SO
4
, which reduces wall moisture pH values
to the 1–2 range, and the acid corrodes the structure wall above
the flow line. A highly corrosive environment is created by the
presence of volatile hydrocarbons and H
2
S. Both concrete
and steel are susceptible to accelerated corrosion rates under
such conditions. Few researchers have discussed the
methodology for carrying out experimental work to determine
the corrosion rate, along with their main corrosion mechanism
and the factors controlling the corrosion rate, and consequently
there is a paucity of published papers in this area.
3
Factors affecting increased sulphide in sewage are outlined
below.
(a) High sewage temperature, accelerating the sulphate/
sulphide conversion process.
(b) High biochemical-oxygen-demand (BOD) sewage,
particularly high-soluble BOD sewage.
(c) Flat sewer slopes producing oxygen-deficient, or ‘septic’
sewage; and the low velocities lengthen detention time and
increase settling of organic solids and grit in the sewer invert.
(d) Long detention times in wet wells, force mains, inverted
siphons or surcharging gravity sewers.
(e) Steep slopes and high flow velocities.
(f) Turbulence caused by inadequate or poor design of
structures: examples are junction structures with colliding
flows, and drop structures and intercepts or force mains that
discharge significantly above the wastewater surface in the
main line.
(g) Changes in slope that lead to hydraulic jumps, abrupt flow
direction changes (angle points) and short radius curves.
Other factors tend to increase the amount of H
2
S escaping
from the wastewater. H
2
S is released primarily as a gas and will
spread in the air. When released as a gas, it will form sulphur
dioxide and H
2
SO
4
in the atmosphere. Sulphur dioxide, a major
component in acid rain, can be broken down further and
accelerates corrosion rates. H
2
S remains in the atmosphere for
approximately 18 h. In some instances, it may be released as a
liquid waste from an industrial facility.
Beck
4
studied the cause of concrete sewer pipe corrosion. The
objectives of the project were to compare the cost for routine
cleaning of interceptors and the accumulative corrosive effects
that excessive deposition have on sewer pipes. Manhole locations
were set up and data were collected from them for pipe wall
deterioration and deposition, throughout the 12 000 ft
(3657.6 m), 42 in. (1.07 m) and 30 in. (0.76 m) concrete
interceptor. Sewer sediment is a type of settleable particulate and
form bed deposit. It has been established that excessive pipe
deterioration and an excessive amount of deposition existed in
the upstream half of the interceptor and low amounts of
deposition and minor deterioration were present in the
lower half.
To monitor the corrosion of the iron pins in the specimen,
electrochemical impedance spectroscopy (EIS) and open-circuit
potential (OCP) serve as valuable tools. Jahani et al.
5
studied the
degradation of a mortar specimen exposed to an acidic sulphate
solution, using iron pins set within the sample with their ends
close to the surface. The corrosion behaviour was monitored
using the EIS and the OCP of the pins. The pH of the test solution
was maintained in the range 4–5 for eight days and 2–3 for
73 days. By using the experimental data, the role of the diffusion
reaction in the deterioration of concrete surfaces was determined.
It is indicated from the OCP of the pins that the pin closest to
the surface of the mortar deteriorates after 36 days. Also it was
observed that 0.82 mm of the mortar was corroded at the end
of the experiment. This establishes the validity of the moving
boundary paradigm for the sulphide corrosion of concrete.
5
The cause of deterioration is mainly determined by petrographic
examinations. A study conducted by Cady and Richard
6
showed
that the affected area in an entrained air void system was the
main reason for the deterioration caused by inadequacy of
entrained air in these areas. Their examinations showed that the
magnesium oxide (MgO) content of the Portland cement in the
affected areas was 3.5 times more than that present in the
unaffected areas. MgO (9.1%) was more than its permissible value
prescribed as per ASTM C-150. Enhanced deterioration was
observed in manhole sections that were located below the frost
line. Freezing and thawing attack caused typical fracture planes
parallel to exposed surfaces. These crack patterns were
characteristic of the expansive reactions. Ramachandran
7
stated
that dead burnt magnesia expands some 17%. This was in the
context of the slow hydration of unreactive material requiring
additional water for hydration over the original mix water. The
volume changes with reactive magnesia as it hydrates in the
cement matrix containing Portland cement and can be
engineered to be neutral. Owing to the fact that hydration of dead
burnt magnesia is a slow process, the change in the volume that
occurs when magnesia hydrates is
MgO(S) þH2O(I) ! Mg(OH)2
4031 þ180 ! 583 molar mass
112þ180 ! 249 molar volumes
This reaction, as in the case with dead burnt magnesia produced
as a result of high-temperature thermal deposition, occurs after
most of the free mixing water has been taken up by the hydration
of the cementitious minerals, mainly comprising tricalicum
silicate and dicalcium silicate, or vacated through bleeding or
evaporation.
7
12 Municipal Engineer 159 Issue ME1 Deterioration of reinforced concrete in sewer environments Parande et al.
It has been generally accepted that concrete corrosion is caused
by bacterial oxidation of H
2
S in sewer systems. Costs related to
sewer replacement and remedies are quite high, but there is
limited knowledge and documentation on the relationship
between H
2
S levels and corrosion rates. This information is
necessary in order to select the appropriate means of H
2
S control
and to conduct a cost–benefit analysis. The effect of the
wastewater composition on corrosion damages in the sewer
pipelines was considered, especially for the steel and cast iron
pipes. The concrete pipes are also susceptible to corrosion
damage, especially in the presence of H
2
S and/or fatty acids.
8
3. ROLE OF MICRO-ORGANISM IN DETERIORATION
OF CONCRETE IN SEWER PIPELINES
Culture-dependent studies have implicated that
sulphur-oxidising bacteria, combined with the bacteria of
the acidiphilium genus, are the main agents of concrete
corrosion in sanitary sewers.
9
Acidophilic iron oxidising bacteria are responsible for the
corrosion of reinforcement. They attack steel to convert ferrous to
ferric oxide and, along with the sulphur-oxidising bacteria, lead
to the corrosion of concrete in many sewers. When the concrete
samples were exposed to a sewer environment containing H
2
Sof
more than 600 ppm, the surface pH of the specimen reduced from
an initial value of 12–13 to a very low value of ,2. This
reduction in pH is attributed to the fact that sulphur-oxidising
bacteria grow on the surface of the specimen, which converts the
H
2
StoH
2
SO
4
. The reduction in pH also takes place internally
where bacterial growth is absent. This may be attributed to the
penetration of H
2
SO
4
into these areas. Formates, such as calcium
formate, inhibited the growth of sulphur-oxidising bacteria and
iron-oxidising bacteria when present in concentrations of more
than 50 ppm.
10
This type of H
2
SO
4
is known as BSA. The main species of
acid-producing bacteria in sewers is thiobacillus supported by
acidiphilum. Fluorescent in situ hybridisation (FISH) studies were
used to identify and enumerate selected bacteria in homogenised
biofilm samples taken from the corroding crowns of concrete.
Direct epiflourescent microscopy demonstrated the ability of
FISH to identify significant numbers of active acidophilic
bacteria among concrete particles, products of concrete corrosion
and other mineral debris. FISH analyses with the species-specific
probe Thio820, and a domain level probe that recognises all
bacteria. Thio-ferro-oxidans and Thio-thio-oxidans comprised
between 12% and 42% of the total active bacteria present in
corroding concrete samples.
10
Babushkin et al.
11
have elaborately studied the mechanism of
chemical and biochemical processes taking place in sewage.
Davis et al.
12
have studied the effect of microbial population in
the loose outer corrosion layer (OCL) and the bound inner
corrosion layer (ICL) of concrete from a corroded sewage
collection system. In order to determine the mineralogical
composition and the strength of samples, chemical and physical
studies were carried out. It was also found that the strength of
concrete was reduced by 20% at crown and springline.
Furthermore, it was demonstrated that after the initial corrosion
of concrete, further corrosion was controlled by the penetration
rate of the acid produced by the acidophilic sulphur-oxidising
micro-organisms (ASOM) and the ASOM itself. This was not the
case in neutrophilic sulphur-oxidising micro-organisms (NSOM).
12
The alkaline nature of concrete with a pH of around 11–13
creates an unfavourable condition for the growth of
micro-organisms.
13
However, the presence of CO
2
and H
2
S brings
acidic properties to the concrete.
14
The detrimental effects of CO
2
on concrete were studied by Ismail et al.
15
Their experiments
showed that atmospheric CO
2
reduces the pH of concrete to 9.5.
A drastic reduction in pH was observed at an atmosphere
containing 5000 ppm of CO
2
. The theory behind this pH
reduction was studied by Thistlethwayte and Goleb.
16
Bacteria of the thiobacillus species stick to the concrete surface
and, if adequate nutrients, moisture and oxygen are available,
begin to reproduce once the pH of the solution is reduced to
approximately 9.
17,18
The five major species of thiobacillus,
which play important roles on concrete, are (a)Thio-oparus,
(b)Thio-novellus,(c)Thio-neapolitanus,(d)Thio-intermedius and
(e)Thio-oxidans. Of these, the first four are categorised as
NSOM and the fifth as ASOM.
Jahani et al.
19
studied the deterioration of concrete in acid
sulphate solutions. The experiments were conducted at a pH of
4–5 for eight days and 2–3 for 13 days. The efficacy of the
diffusion-reaction-based model with a moving boundary for the
corrosion process was analysed from the experiment. The
corrosion rate constant for the specimen and the effective
diffusion rate of H
2
SO
4
in the corrosion layer were calculated
from the acid neutralisation rates in the solution. It was observed
that the cross-sectional area of 0.8mm
2
of the sample was
corroded at the end of the experiment. The moving boundary
model was validated by the experimental data obtained and it can
be inferred that the effective diffusion rate reduced with age of
the corrosion product being formed.
19
Maintenance holes are provided to access a sewerage system for
investigations, clearance of blockages and maintenance
purposes. Van Mechelan and Polder
20
have studied the rate of
attack of concrete in sewer manholes and subsections by BSA
attack. Scanning electron microscopy (SEM) revealed details of
the attacked concrete layer. The corrosion is predominantly
caused by diffusion of sulphate into sound concrete beyond the
gypsum-rich layers. Microstructural properties were also studied.
Investigations show that the highest rate of attack of concrete by
H
2
SO
4
is 3 mm per year,
20
which may vary depending on the pore
structure and permeability of concrete.
3.1. Chemistry behind H
2
S attack
Bacteria reduce the sulphur-containing organic compounds and
sulphates to form sulphides. As a result of this property, septicity
arises in the biowastes from the activity of the bacteria under
anaerobic conditions. A part of the sulphur, after reduction, is
released into a large percentage of sulphide ions into the
environment, and a part is released as free H
2
S. Only the
bacteria assimilate a very meagre part of the reduced sulphur.
Proteolytic bacteria in the absence of oxygen act on the organic
compounds of sulphur to form initially H
2
S. The proportions of
these sulphide ions are very sensitive to the pH of the
solution, temperature and ionic strength. As a result, various ions
are formed. They are predominantly H
2
S, HS
2
and S
22
. The
Municipal Engineer 159 Issue ME1 Deterioration of reinforced concrete in sewer environments Parande et al. 13
sulphate-reducing bacteria do not reduce the contaminants of
fresh manure. This defect is, however, overcome by the fact that
the bacteria from the digestive system can assimilate these
organic compounds into lactic acid, which is one of the
common substances used by the H
2
S-reducing bacteria.
21
CH3CHOHCOOH þ043 H2SO4þ0067 NH3!
Desulphovibriod
desulphuricans
033 CH14N02O04þ096 CH3COOH
þ043 H2Sþ07CO
2þ094 H2O
Generally sulphate-reducing bacteria suffer from an inability to
use the acetic acid as a source of carbon. There are, however,
exceptions, one of which is Desulphotomaculum acetoxidans,
an acetic-acid-based H
2
S, the production of which is
illustrated below
CH3COOH þSO2
4!
Sulphate reducers H2Sþ2HCO
3
Aerobic Thiobacilli bacteria generally convert the H
2
S
developed during the decomposition of the organic
substances to sulphate. Oxidation of H
2
S occurs in several
stages as follows
21–25
2H2SþO2!
Green sulphur bacteria 2H2Oþ2S þ528J
S2þ3O2þ2H2O!
Purple sulphur bacteria 2H2SO4þ1231J
The H
2
SO
4
formed as shown above is very corrosive to the
concrete tanks and sewer pipelines.
In addition to the above, the sulphate ions also attack the
concrete directly thereby resulting in major corrosion. They also
react with the calcium present in the cement to form gypsum, as
shown below
2H2OþCa2þþSO2
4! CaSO42H2O
and with the calcium aluminium hydrate to form ettringite. In the
above reactions, the formation of products causes a major
increase in the volume of the cement and thereby leads to
cracking and damage in the structure. The volume increase rate is
124% for gypsum and 227% for ettringite. There is a large
increase in the stress on the surface of the cement. This is even
further worsened by the fact that H
2
S also attacks the concrete
and the steel reinforcement. It reacts with lime to produce a
soluble product
Ca(OH)2þ2H2S! Ca(HS)2þ2H2O
Ferrous sulphide is formed as a result of the H
2
S reaction with the
reinforcing steel through the cracks produced by sulphate
attacks. Water and oxygen, also migrating through the cracks,
form iron oxides and hydroxides. The products formed here also
increase the volume of the concrete surface thereby leading to
cracks and corrosion.
4. PREVENTING CONCRETE DETERIORATION
How does an engineer design a wastewater system to counter the
corrosion effects of H
2
S gas and H
2
SO
4
? The simple answer is to
reduce the conditions that generate H
2
S. However, this is not
always possible or economical. Excluding piping, approximately
40% of a wastewater system is made up of concrete structures;
therefore, some means of reducing concrete corrosion must be
utilised. It must be effective and economical. It can be achieved
either by treatment of the sewer or the modification of the
concrete. Concrete protection methods commonly used for
structures include modifications of concrete mix, design;
coatings painted or rolled onto the concrete surface; and liners
that have integral locking projections cast into the concrete.
Modifying the concrete mix usually involves increasing the
alkalinity, since the corrosion rate is inversely related to concrete
alkalinity. The following points are to be considered during the
construction of sanitary works
(a) use of ASTM type V rather than ASTM type II cement, or
ASTM type II low alkali cement rather than type II
(b) addition of microsilica to precast concrete sewer pipe
doubles the corrosion rate of conventional concrete pipe
when exposed to acid
(c) high-alumina cement increases corrosion rates at typical pH
moisture levels of 1–2 on structure walls.
4.1. Treatment of sewers
Sydney et al.
26
studied the control of concrete sewer corrosion
by the crown spray process. In this method, a high pH mixture is
sprayed onto the crown area of the sewer. Deactivation of
sulphur-oxidising bacteria and neutralisation of the acid are
some of the main principles in this process. The sewer crown
environment must be rendered unfavourable for the growth of
sulphur-oxidising bacteria. A residual alkali on the sewer crown
has been left to neutralise the acid produced. These are some of
the major applications of the crown spray process. Measurements
were made before and after the treatment for the surface pH of the
sewer ground to check the effectiveness of the treatment. Various
chemical treatments with biocides were studied for deactivation
and regrowth of organisms. It has been established that
magnesium hydroxide slurry of pH 10.5 is used to neutralise
acidic wastes and is the most effective and non-hazardous
chemical tested to date. The above chemical, applied at a rate of
50%, has reduced the population of sulphur-oxidising bacteria to
about one-millionth of the initial value, and achieved a constant
pH of 9 for approximately nine nine months.
26
In another study,
the effect of the total dissolved organic carbon (DOC), suspended
solids; dissolved oxygen present in the sewers on the
deterioration of concrete was studied by Chen et al.
27
They also
established a treatment technique for the reduction of the DOC,
where the sewer was passed through a 1.5 km section having
inner diameter of 450 mm constructed over a slope of 0.0075.
Approximately 14% of the DOC was removed for a retention time
of 18 min. Batch tests were carried out for raw sewage, suspended
solids or settled solids. As a result, the raw sewage yielded 1.3mg
DOC/mg of sample, whereas the suspended solids yielded a
2.6 mg DOC/mg dry weight. From this study they concluded that
for a 15 km pipeline approximately 39.133 kg of DOC can be
stabilised per day.
4.1.1. Modification of material structures. Werner and
Krausewald
28
studied an innovative presentation consisting of a
concrete pipe shaft system for municipal wastewater along with
an integrated air/H
2
O press-testing function for the detection of
leakages in the structure of the pipe or the pipe joints: a socket
seal. The main function was to detect exfiltration or infiltration
and achieve an integrated electronic memory for a network
storage in-house sewer information system. Heil and Kloss
29
14 Municipal Engineer 159 Issue ME1 Deterioration of reinforced concrete in sewer environments Parande et al.
studied the concrete corrosion caused by SO
4
22
in sewage
systems. According to German communal environmental laws
the limit for SO
4
22
is 400–600 mg/l. In view of the current state of
technology, however, the adonising plant cannot comply to this
limit. Heil and Kloss suggested that the maximum SO
4
22
values
for the anodising plants should be determined individually
according to the composition of sewage or the quality of
concrete pipes. Investigations have shown, however, that
SO
4
22
-contaminated anodising effluents with concentrations of
.600 mg/l have not caused any corrosion of concrete pipes.
29
The corrosion phenomena caused by both chemical and bacterial
activity have been given special emphasis recently. New aspects
of the subjects are highlighted by investigations on particularly
aggressive sites, which suggest that calcium-aluminates-based
binders can be appropriate in such environments.
30
In view of the
above, Cabiron and Heliard
31
commented that the proliferation of
bacteria produces bio-H
2
SO
4
as a result of which the bacterial
corrosion occurs. It has been reported that the concrete matter
made of alumina cements has a better resistance than Portland
cement. This is because the resistance to sulphates is attributed to
the absence of Ca(OH)
2
in hydrated high alumina cement and
also to the protective influence of the relatively inert alumina gel
formed during hydration. Lean mixes are much less resistant to
sulphates and also the chemical resistant decreases drastically
after conversion of both CAH
10
and C
2
AH
8
3CAH10 ! C3AH6þ2AH3þ18H
Maeda
32
postulated that synthetic sheets, having integrally
moulded anchors and concrete placed on the anchor side so as to
protrude the anchors from the concrete surfaces, should comprise
the lining sheets. The anchors are buried in the mortar applied to
the surfaces so as to bond the lining sheets firmly to the inner
surfaces of sewers and sewer systems.
In another study, Northwood et al.
33
studied the deterioration of
concrete sewer pipelines in America owing to the presence of
chloride ions and the performance of the modified structure in
the same environment. A conventional dry process plant
modified the composition of cement so that the intrusion of
chloride ions was controlled. Inter-ground silica fume cement
was used to reduce the handling difficulties of silica fumes. The
material was tested for its chloride permeability and chloride ion
diffusivity. This resulted in a very small increase in the total
construction cost owing to the modification of the material and a
change in the casting process.
Silica reacts with Ca(OH)
2
in the presence of water to form
cementing compounds consisting of calcium-silicate hydrate.
The silica fume (SF) concrete improves the strength efficiency
and durability characteristics. Typically 5–10% of SF is added.
During the chemical reaction between SF and components in the
pore water, the content of components keeping a high pH value is
reduced, especially Ca(OH)
2
and potassium. A high level of alkali
content in the cement accelerates the reaction rate of the SF. It
has been reported that the addition of up to 8% SF significantly
reduces permeability. Owing to reduced pH value in concrete
with SF, it is expected that the chloride binding capacity also
should be reduced. Chloride binding in cementing materials is
dominated by the content of C
3
A (tricalicum aluminate) and C
4
F
(tetra calcium ferrite) regardless of the chloride source, both
forming Fridels salts. Sulphates in cement, however, form
stronger bonds than the chloride so only a fraction of the C
3
A and
C
4
F is accessible for chloride-binding capacity. Since these
materials form additional calcium aluminates hydrates in their
reaction, SF will decreases the chloride-binding capacity.
Dumas
34
studied in detail the characteristics and durability of
aluminous cements in relation to their suitability for repair of
sewers. An effective solution based on a hydraulic binder has
been suggested for sewers and sewer systems. A detailed study
has been made of concrete containing pozzolans such as silica
fume and fly ash, more than in conventional cement, for
converting the calcium hydroxide generated by the hydration of
cement to calcium silicate fumes H-type hydrates.
35
Soutsos
et al.
36
concluded that different mix proportions for concrete
with regard to silica fumes offer better durability for concrete in
terms of chloride and sulphate-induced corrosion. The corrosion
process of reinforced concrete may be divided into two stages:
initiation period and propagation. Silica fume affects both stages.
In the initiation period, carbonation is occurring or chloride ions
are transported into the concrete. The carbonation results in
reduced pH values, allowing corrosion to start. SF may be
expected to reduce the resistance against carbonation owing to
the level of Ca(OH)
2
; SF will also improve the resistance against
CO
2
ingress. Addition of SF also improves pore refinement
structure thereby reducing permeability. The concentration of
chloride ions in the pore solution reducing the ion mobility may
be another reason.
4.1.2. Coating for corrosion prevention. The behaviour of
concrete with polymer when exposed to H
2
SO
4
medium has been
studied since 2002.
37
The mass transfer coefficient ratio of the
concrete to the polymer was over 12. The chemical resistance of
the coating was studied using coated concrete with pinholes. The
effect of the pinhole sizes on the performance of concrete was
studied by modelling the weight change in the coated concrete.
37
A further study by Wehr
38
deals with development of a polymer-
modified resin cement mortar which, when coated over the
concrete surface, increases the corrosion resistance of the sewer
concrete pipeline. The important pretreatments adopted for this
are that the surface of the concrete should be flushed and a wash
primer should be sprayed over the surface. The total lining
thickness was 10–14 mm.
Polymer modification of concrete influences to a large extent the
microstructure of the material. Owing to the film-forming
capacity of the polymer particles, an interpenetrating network of
cement hydrates and polymer particles exists in which the
aggregates are embedded.
39
Polymer modification also
influences the transition zone between the bulk cement-polymer
co-matrix and the aggregates. The growth of large crystals is
decreased and possibly the calcium ions react with certain
carboxylate groups of the polymers. The main improvements
attributed to the presence of the polymer film are bridging of
micro-cracks, reduction of pore size and blocking of pores, which
results in a reduced permeability of the concrete. All of these
properties should lead to an improved resistance of the concrete
against acid attack. In fact, the lower permeability should slow
down the penetration of H
2
S, the ingress of the micro-organisms
and the produced acid. Also, in the case of production of
expansive reaction products, polymer-modified concrete is
Municipal Engineer 159 Issue ME1 Deterioration of reinforced concrete in sewer environments Parande et al. 15
expected to be more resistant to this detrimental action because
of the capacity of the polymer film to bridge microcracks.
Cathodic protection by electrochemical methods can be applied
for the protection of steel-reinforced rods from corrosion in
sewage lines.
40
4.1.3. Engineering design. The major factors that come into
play in sewer pipes are: (a) internal pressure; (b) pressure result-
ing from external load; (c) temperature stresses; and (d) flexural
stresses. Sewer maintenance manholes should be of a size and
shape that provides reasonable access for personnel and
equipment to flow channels, with a minimal likelihood of
problems. General access is maintained on lengthy sewers by
providing intermediate maintenance holes. Maximum
maintenance hole spacing is dependent on whether entry into the
pipeline is possible. For pipelines of less than DN600, a numerical
designation of the size of a unit or a component within a structure
is given, which is a convenient integer approximately equal to
the manufacturing dimension in millimetres for internal diameter
(DN): in other words, the nominal diameter (ND) external of a
pipe or a manhole. The exact external diameter corresponding
to an ND is specified in the relevant standards subjected to a
tolerance limit. DN600 is the nominal size of pipe capacity used
in sewage systems. The maximum spacing is dependent on the
type of equipment available to maintenance crews. The DN sizing
is given in Table 1. It is considered that curved alignments will
require more maintenance than straight alignments. Visual
inspection from maintenance hole to maintenance hole is
generally not possible. As a consequence, closer maintenance
hole spacing is required on these alignments.
In order to increase the watertightness of shaft rings and cones
of precast components for sewer pipelines, different joint types
were adopted and wall thickness was increased. The hidden
defects in the joints were rectified by introducing a concrete joint
structure.
41
Some of the case studies are given and discussed
below.
The East Bay, California, USA, municipality effected the
rehabilitation of the wood street interceptor by using the Danby
and Linabond process. By doing so, the lifespan of the pipeline,
which was already 50 years old, was increased by 50–100 years.
In the Danby process, profiled polyvinyl chloride (PVC) strips are
spirally wound through existing manholes to form a liner that
needs grouting. PVC forms are installed over the interior surface
of the pipe and a cementitious grout is placed behind the forms in
sewer lifts. In the Linabond rehabilitation a high-strength
thermosetting is sprayed over the surface of the concrete pipe.
A rigid cellular plastic is formed when the resin expands owing to
an exothermic reaction.
42
An interesting observation was made in a Los Angeles county
concrete sewer. Following an industrial waste pretreatment, the
corrosion rate increased sharply. When investigated, it was found
that the corrosion was not only increased by sulphide generation but
also by an increase in the concentration of transition metals such as
Ni, Fe, Pb, Cd and Cr. None of these metals was present before the
pretreatment process. Morton et al.
43
also conducted a series of
experiments in order to determine the effects of transition metals.
They also found that Cr, Cn
2
, Cu, Zn and Ni inhibited the sulphur-
reducing bacteria (SRB) activity in the reactor. A model with a
Monod-type function has been made in a pilot scale with a
maximum corrosion rate of 16 mm/year at 258C at 2 ppm H
2
S.
Maintaining the H
2
S concentration at zero ppm can prevent
concrete corrosion. This can be done by controlled treatment with
nitrate. The nitrate doseis made based on the Nutriox concept where
the dosage is dependent on the flow, temperature, sewer design and
the sewage concentration. For a more cost-effective treatment it is
advisable to have a longer hydraulic retention time.
44
Van Mechelen and Polder
45
studied the level of aggressiveness
of BSA present in ten different manholes on four different
types of concrete. Significant differences in corrosion rates in
different concrete types were observed.
5. REPAIRS AND REHABILITATION
Permeable slag sand waste concentration for repairing was
studied by Pernice
46
in different ratios in concrete containing
5–20% cement, 4–20% vitrified and milled blast furnace slag,
5–20% crystal and milled blast furnace slag and 50–75% sand of
blast furnace slag. The concrete is sprayed onto the walls of the
galleries and smoothened. Pernice suggested that the application
of this repair material prevented further deterioration.
Kaempfer and Berndt
47
stated that Germany spends
approximately US$100 billion in maintenance and repair of
private and public sewage systems. About 40% of the damage in
concrete pipelines is caused by bio-generated H
2
SO
4
as a result of
long flow durations and improper ventilation of wastewater.
Kaempfer and Berndt have investigated the corrosion of concrete
in BSA. They have devised a simple reproducible comparative
simulation method for testing the service life in the cases of
dissolute and expansive chemical attack.
Atsunori and Maeda
48
commented that sulphur-oxidising
bacteria deteriorate a repair system of concrete structures used
for sewerage treatments or sewer piping by oxidising the H
2
S and
producing H
2
SO
4
. The rate of corrosion has exceeded 4 mm/year.
A repair method for corroded concrete by employing
high-density polyethylene (HDPE) sheets is described in their
paper. An innovative method was designed in which fresh mortar
containing bacterium inhibitors was applied directly by HDPE
sheets. This repair method is advantageous because it can be
applied to large sheets without making wrinkles, there are less
holes to support the concrete panels and there are fewer welding
spots. If sulphate were to remain in the concrete, it would react
with the fresh mortar in the cement and produce ettringite that
would peel the mortar from the concrete. It was observed that
when the sulphate content of the cement was within 2–5%, the
Sl No. Pipe size (DN)
Maximum maintenance hole
spacing: m
Straight sewers Curved sewers
1 150–450 100 80
2 525–900 150 100
3 1050–1650 300 300
4.1800 500 500
Table 1.
16 Municipal Engineer 159 Issue ME1 Deterioration of reinforced concrete in sewer environments Parande et al.
adhesive strength between the old concrete and mortar was
.1.47 N/mm
2
. Sulphate, which is present in Portland cement as
gypsum, is added during the manufacture to control the set, but is
limited to 3% expressed as SO
3
by the mass of cement. There is no
test available which can determine the safe sulphate content. A
limit of 4% by mass of cement is, however, considered
reasonable. The primary product of concrete decomposition by
H
2
SO
4
is calcium sulphate. This provides little structural stability
in the wet condition and it generally exists in paste form on the
concrete surface. This paste layer lowers corrosion rate and, as
H
2
SO
4
has to penetrate through this layer, this is sometimes
advantageous. Consequently, if this layer is removed by high
flow then the corrosion is accelerated.
6. ODOUR
Odour can be defined as the ‘perception of smell’ or in scientific
terms as ‘a sensation resulting from the reception of stimulus by
the olfactory sensory system’. Whether pleasant or unpleasant,
odours are induced by inhaling airborne volatile organics or
inorganics. With a growing population, industrialisation and
urbanisation, the odour problem has been reaching
an objectionable proportion. Urbanisation without proper
sanitation facilities is a major cause of odour problems. Rapidly
growing industrialisation has aggravated the problem through
odour produced in industrial operations. Undesirable odours
contribute to air-quality concerns and affect human lifestyles.
Odour is undoubtedly the most complex of all the air pollution
problems.
6.1. Measurement and monitoring of odour
6.1.1. Odour intensity. Odour intensity is the strength of
the perceived odour sensation. It is related to the odorant
concentration. The odour intensity is usually stated according to
a predetermined rating system. A widely used scale for odour
intensity
49
is the following
0 no odour
1 threshold level
2 definite odour
3 strong odour
4 overpowering odour
Gunster
50
stated that, if the natural microbial activity of micro-
organisms in sewer systems can be supported by controlled
dosage of a special nitrate solution, the problems of corrosion by
H
2
SO
4
and odour of H
2
S can be solved. The growth of
denitrifying micro-organisms in place of sulphate-reducing
micro-organisms is done by the addition of the above special
nitrate solution. As a result, denitrification prevents the
occurrence of anaerobic conditions and hence sulphide
formation. Barjenbruch and Matthias
51
published a review on
methods to minimise the odour formation and corrosion caused
by H
2
S in sewer systems. A dosage of Ca(NO
3
)
2
is given to prevent
H
2
S formation: this is adjusted for anoxic conditions. According
to Eiswirth et al.
52
oxygen-containing liquids (e.g. H
2
O
2
,H
2
O
with dissolved O
2
) or gases (air or pure oxygen) should be
transported through a perforated flexible tube into sewers as far
as 10 km and distributed homogeneously to combat odour and
prevent corrosion. The tube containing polyurethane is
individually perforated. Using accurate injection, the required
amount of oxygen can be decreased by 480%. Table 2 gives the
causes of odour from the industry.
6.1.2. Odour measurement. The olfactometric methods of
odour measurement fall into two categories: determination of the
threshold concentration of odoriferous gases; and determination
of the type and intensity of odour.
(a) Threshold concentration of odoriferous gases. European
threshold concentration ranges for some unpleasant odours
are presented in Table 3.
(b) Determination of the type and intensity of the odour.
Generally odour intensity increases with the odorant
concentration. The relationship between intensity and
concentration can be expressed as
P¼Klog S
where Pis the odour intensity, Kis a constant and Sis the odour
concentration.
Currently, the preferred and internationally standardised
methods of measuring odour are the Dutch Standard
Method (NVN 2820)
53
and the more recent European
Standard Method.
6.2. Odour control
An array of treatment technologies are available for control
of odour from gas streams collected through process
Sl No. Industry Odorous material
1 Pulp and paper Mercaptans, hydrogen sulphide
2 Tanneries Hides, flesh
3 Fertilisers Ammonia, nitrogen compounds
4 Petroleum Sulphur compounds from crude oil, mercaptans
5 Chemical Ammonia, phenols, mercaptans, hydrogen sulphide, chlorine, organic products
6 Foundries Quenching oils
7 Pharmaceuticals Biological extracts and wastes, spent fermentation liquors
8 Food Cannery waste, dairy waste, meat products, packing house wastes, fish cooking odours,
coffee roaster effluents
9 Detergent Animal fats
10 General Burning rubber, solvents, incinerator, smoke
11 Swine operations Hydrogen sulphide and ammonia
12 Wastewater treatment/plant Hydrogen sulphide
13 Municipal solid waste landfill Hydrogen sulphide
Table 2. Sources of odour
Municipal Engineer 159 Issue ME1 Deterioration of reinforced concrete in sewer environments Parande et al. 17
ventilation systems. These include: mist filtration; thermal
oxidation/incineration; catalytic oxidation–biofiltration;
adsorption; wet scrubbing/absorption; chemical treatment;
and irradiation.
The choice of the technology is often influenced by the following
factors
(a) volume of gas (or vapour) being produced and its flow rate
(b) chemical composition of the mixture causing the odour
(c) temperature
(d) water content of the stream.
In 1991 Lian et al.
55
studied the comprehensive system-wide
odour/corrosion control programme using multiple technologies
to achieve short- and long-term odour control. This programme
primarily formulates methods for the reduction in production
and release of H
2
S and installation of better odour control. The
programme consists of three phases
(a) analysis of odour and corrosion problem areas
(b) short-term implementations to provide immediate relief
(c) long-term analysis and recommendations.
There is no single treatment technique that could provide a remedy
for all of the conditions that were found. Implementation of a
combination of treatments could solve each individual problem.
7. CONCLUSIONS
The theory of microbial-induced concrete deterioration that has
been presented in this review explains both the chemical and
mechanical aspects of concrete. The suggestions of various
researchers for modification of structures, composition of cement
and biological activities taking place in sewers that lead to the
deterioration of concrete are to be practiced. Suitable measures
are to be adopted before installation of sewer pipelines, and
treatment of sewage should be carried out for durability and
performance of structure. Manholes should be provided at
regular intervals, which can avoid damage. Odour impact
assessment is an effective tool for the preparation of
environmental management plans, development of appropriate
regional and local planning and development control
instruments and odour regulation. Odour impact areas should be
plotted using nomograms of odour concentration corresponding
to the same values for odour impact criteria.
Suitable materials and design can be used to safeguard the
structure from deterioration by sulphide attack from sewage.
Repair work should be carried out at regular intervals to check
the sedimentation layer formed in the sewer pipelines. This can
prevent severe damage—that is, the collapse of the whole
structure.
8. ACKNOWLEDGEMENT
The authors thank the Director of the Central Electrochemical
Research Institute (CECRI) for kind permission to publish this
paper.
REFERENCES
1. KENETH K. K. and KARL E. K. Corrosion below sewer structure.
American Society of Civil Engineering,1991,61, No. 9, 57–59.
2. FRENAY J. W. and ZILVERBER H. Duurzaamheid van beton in
agraiche milieus (Durability of concrete in agricultural
environments). IMAG-DLO, Wageningen, the Netherlands,
1993, pp. 93–17.
3. HORLYCK L. and SALOME F. Corrosion rates of concrete and
steel in sewers. In Proceedings of Corrosion Prevention.
Australasian Corrosion Association, 1999, pp. 71–77.
4. BECK G. S. Deposition is the number one cause of concrete
sewer pipe corrosion. Proceedings of the 67th Water
Environmental Federation Annual Conference Exposition,
London, 1994, 3, 37–46.
5. JAHANI F., DEVINNY J., MANSFELD F., ROSEN I. G., SUN Z. and
WANG C. Investigations of sulphuric acid corrosion of
concrete II—Electrochemical and visual observations.
Journal of Environmental Engineering, American Society of
Civil Engineers, 2001, 127, No. 7, 580–584.
6. CADY P. D. and RICHARD W. E. Petrographic examinations aid
in establishing the causes of deterioration of pre-cast
concrete sewer manhole sections. 1061 Petrographic Applied
Cement Concrete Aggregates, 1990, 182–193, American
Society for Testing and Materials Special Technical
Publications.
7. RAMACHANDRAN V. S. Concrete Sciences. Heyden, London,
1981, pp. 356–365.
8. DIDENKO E. A., KHROMCHENKO Ya. L. and SVETLOPOLYANSKII
V. A. Effect of the composition of transported wastewater on
the status of sewer pipelines systems. Vodonsnabznenie i
sanitarnaya Tekhnika, 2002, 5, 33–35.
9. ASO I., TOGASHI S. S., TANIGAWER M. and YAMANAKA T.
Corrosion, by bacteria, of concrete in sewer sewage systems
and inhibitory effects of formates on their growth. Water
Research, 2002, 36, No. 10, 2636–2642.
10. HERNANDEZ M., MARCHAND E. A., ROBERTS D. and PECCIA J.
In situ assessment of active thiobacillus species in
corroding concrete sewers using fluorescent RNA probes.
International Bio-deterioration and Biodegradation, 2002,
49, No. 4, 271–276.
11. BABUSHKIN V. I., PLUGIN A. A., ZELEUSKY P. Y. U. and
DROZD G. Y. A. Concrete of sewage collectors and their
protection: corrosion mechanism. Proceedings of the 10th
International Congress in Chemistry Cement, Goeteborg,
Sweden (JUSTNERS H. and AMARKAI A. B. (eds)). 1997, 4,p.4.
12. DAVIS J. L., NICA D., SHIELDS K. and ROBERTS D. J. Analysis
of concrete from corroded sewer pipe. International
Bio-deterioration and Biodegradation, 1998, 42, No. 1, 75–84.
Compound
Detection
threshold:
mg/m
3
Compound
Detection
threshold:
mg/m
3
Acetic acid 25–10 000 Indole 0.6
Propanic acid 3–890 3-methyl
indole
0.4–0.8
Butanoic 4–3000 Methanethiol 0.5
3-methyl
butanoic acid
5 Dimethyl
sulphide
2–30
Pentanoic acid 0.8–70 Dimethyl
disulphide
3–14
Phenol 22–4000 Dimethyl
trisulphide
7.3
4-methyl phenol 0.2–35 Hydrogen
sulphide
0.1–180
Table 3. European threshold concentration ranges
18 Municipal Engineer 159 Issue ME1 Deterioration of reinforced concrete in sewer environments Parande et al.
13. ISLANDER R. L., DEVINNEY J. S., MANSFELD F., POSTYN A.
and SHIH H. Microbial ecology of crown corrosion in
sewers. Journal of Environmental Engineering, 1991, 117,
No. 6, 751–770.
14. LEA F. (ed.) The Chemistry of Cement and Concrete, 3rd edn.
Edward Arnold Press, London, 1970.
15. ISMAIL N., NONAKA T., NODA S. and MORI T. Effect of
carbonation on microbial corrosion of concrete. Journal of
Construction Management and Engineering, 1993, 20, 133–138.
16. THISTLETHWAYTE D. K. and GOLEB E. E. Sewer and storm water,
the composition of sewer air advances in water pollution
research. Proceedings of the 16th International Congress on
Water Pollution Research, Jerusalem, 1972, 281–289.
17. MORI T., NONAKA T., TAZAKI K., KOGA M., HIKOSAKA Y. and
NODA S. Interactions of nutrients, moisture, and pH on
microbial corrosion of concrete sewer pipes. Water Research,
1992, 26, No. 1, 29–37.
18. RIGDON J. H. and BEARDSLEY C. W. Corrosion of concrete by
autotrophes. Corrosion, 1956, 14, 60–62.
19. JAHANI F., DEVINNY J., MANSFELD F., ROSEN I. G., SUN Z. and
WANG C. Investigations of sulphuric acid corrosion of
concrete. I, modelling and chemical observations. Journal
of Environmental Engineering, 2001, 127, No. 7, 572–579.
20. VAN MECHELAN T. and POLDER R. B. Biogenic sulphuric
acid attack on concrete in sewer environments.
Proceedings of the International Conference on the
Implications of Ground Chemistry and Microbiology for
Construction (HAWKINS A. (ed.)). A. A. Balkema, Rotterdam,
1997, pp. 511–524.
21. JOBBAGY A., SZANTO L., VARGA G. I. and SIMON J. Sewer
system odour control in the lake Balaotn area. Water Science
and Technology, 1994, 30, No. 1, 195–204.
22. ZHU J., RISKOWSKI G., MACKIE R. and DAY D. Bacterial
colonization on metal surfaces in animal building:
implication for microbial induced corrosion. Transactions of
the American Society of Agricultural Engineers, 1994, 37,
No. 3, 929–937.
23. HEUER J. J. M. B. and KASKENS H. J. Prevention of concrete
corrosion and odour annoyance with bio-filtration. Proceedings
of the International Conference on Sewage into 2000, Water
Science and Technology, 1993, 27, No. 5–6, 207–218.
24. ALEKSEEV S. N., IVANOV F. M., MODRY S. and SCHIESSEL P.
Durability of Reinforced Concrete in Aggressive Media.
A. A. Balkema, Brookfield, VT, 1993.
25. SAND W., BOCK E. and WHITE D. C. Applied electron
microscopy in the biogenic destruction of concrete and
blocks—use of the transmission electron microscope for
identification of mineral acid producing bacteria.
Proceedings of the 8th International Conference on Cement
Microscopy, Orlando, 1986.
26. SYDNEY R., ESFANDI E. and SURAPANENI S. Control of
concrete sewer corrosion via the crown spray
process. Water Environment Research, 1996, 68, No. 3,
338–347.
27. CHEN G.-H., LEUNG D. H.-W. and HUANG J.-C. Removal of
dissolved organic carbon sanitary gravity sewer. Journal of
Environmental Engineering, 2001, 127, No. 4, 295–301.
28. WERNER D. and KRAUSEWALD J. A novel concrete pipe-shaft
system with integrated leakage alarm, location and sealing
function and a primary data base function. Korrespondenz
Abwasser, 1996, 43, No. 5, 751–752, 755–756, 759–761.
29. HEIL G. and KLOSS S. Are sulfate containing effluents from
anodizing plants aggressive to concrete? Korrespondenz
Abwasser, 1996, 43, No. 11, 1985–1990.
30. DUMAS T. Calcium aluminate mortars and concretes. An
application to sewer pipes in harsh environments. Proceedings
of the International Conference on the Implications of Ground
Chemistry and Microbiology for Construction (HAWKINS A.
(ed.)). A. A. Balkema, Rotterdam, 1997, pp. 511–524.
31. CABIRON J. L. and HELIARD L. A. New 100% alumina mortar
for bacterial corrosion protection. Technical Industrial
Mineral, 2000, 7, 104–107 (Fr).
32. MAEDA T. Anticorrosive Lining Sheets. Japan Patent 160 373,
June 2000.
33. NORTHWOOD D., CAIL K., MACDONAL D. and KEVIN A.
High performance concrete pre-cast sewer pipe. Advances in
concrete Technology, 1997, American Concrete Institute,
Special Publication 171, 201–208.
34. DUMAS T. Sewers and sewer systems: A durable and effective
solution based on a hydraulic binder. L’Eau L’Industrie Les
Nuisances, 1989, 129, 61–63.
35. IRIYA K., UEGAKI Y. and KUBO I. Acid Resistant Concrete and
Mortar for Sewer Pipeline. Japan Patent 146 720, May, 2003.
36. SOUTSOS M. N., PANTELI F. and KYRIACOS K. K. Examples of
silica fume usage in Cyprus. Concrete International, 1996, 18,
No. 4, 37–42.
37. VIPULANANDAN C. and LIU J. Film model for coated cement
concrete. Cement and Concrete Research, 2002, 32, No. 12,
1931–1936.
38. WEHR L. Sewer lining with a polymer resin modified cement
mortar, 3R, International, 1992, 3, No. 1/2, 59–63.
39. OHAMA Y. Handbook of Polymer-modified Concrete and
Mortars, Properties and Process Technology. Noyes,
New Jersey, 1995, p. 236.
40. SHATRIYAN S. N. Electrochemical Method for Cathodic
Protection of Steel Reinforcing Rods from Corrosion in
Prefabricated Concrete for Sewage Lines. Russian Patent
2075 542, March 1997.
41. TELSER W. A. The problems of joints in pre-cast shafts for
conduit type sewers solved (or) unsolved? Betonwerk
Fertigteil-Teckhnika, 1992, 58, No. 7, 74–79.
42. GIRMA E., BELLOWS P. and YOLOYE O. Not your average
wallpaper rehabilitation of the wood street interceptor.
Proceedings of the 74th Water Environment Federation
Annual Conference & Exposition, Atlanta, 2001, 3722–3735.
43. MORTON R. L., YANKO W. A., GRAHAM D. W. and ARNOLD R. G.
Relationships between metal concentrations and crown
corrosion in Los Angeles county sewers. Research
Journal of Water Pollution Control Federation, 1991, 63,
No. 5, 789–798.
44. AESOY A., OSTERHUS S. W. and BENTZEN G. Controlled
treatment with nitrate in sewers to prevent concrete
corrosion. Water Science and Technology: Water Supply,
2002, 2, No. 4, 137–144.
45. VAN MECHELEN A. C. A. and POLDER R. B. Degradation of
concrete in sewer environment by biogenic sulphuric acid
attack. Proceedings of FEMS Symposium in Microbiology
Civil Engineering, 1990, 59, 146–157.
46. PERNICE M. Manufacture of Easily Pumpable Slag Sand-based
Concrete for Repairing Sewer System Galleries and its Use
and Manufacture. France Patent (Fr. Demande Fr) 2728 255,
June 1996.
Municipal Engineer 159 Issue ME1 Deterioration of reinforced concrete in sewer environments Parande et al. 19
47. KAEMPFER W. and BERNDT M. Estimation of service life of
concrete pipes in sewer networks. Proceedings of the 8th
International Conference on Durability of Building
Materials and Components National Research Council of
Canada,Ottawa (LACASSE M. A. and VANIER D. (eds)). 1999,
1, 36–45.
48. ATSUNORI N. and MAEDA T. A repair system of concrete
corroded by bacteria using HDPE sheets and mortar
admixed with inhibitor. RILEM Proceedings on
Adhesion between Polymers and Concrete, RILEM, 1999,
pp. 497–510.
49. DAVID C. and VOCTER J. G. Odour investigation and control at
WWTP in Orange County, Florida. Environmental Progress,
2001, 20, No. 3, 133.
50. GUNSTAR P. Corrosion avoidance and odour removal
using Nutriox concept. ATV—DVWK-Schriftenr, 2000, 20,
925–930.
51. BARJENBRUCH and MATTHIAS. Avoiding odour development
in sewers. Wasserwirtsch, wassertech, 2001, 4,
35–38 (Ger).
52. EISWIRTH M., HOTZL H., SCHNEIDER T., WEBBER K.
and WETH N. Odour removal and corrosion
prevention in wastewater canals. Umwelt Praxis, 2001, 4,
33–35 (Ger).
53. NETHERLANDS NORMALIZATION INSTITUTE.Provisional
Standard: Air Quality Sensory Odour Measurement using
an Olfactometer. NNI, the Netherlands, 1996, NVN 2820.
54. EUROPEAN COMMITTEE FOR STANDARDIZATION (CEN). Air
Quality Determination of Odour Concentration by Dynamic
Olfactometry. CEN, Brussels, 2003, EN 13725.
55. LIAN Z., TIM C., KANIZ K. and SIDDIQUI F. Long-term
evaluation of an industrial-scale bio-filter for odour control
at a large metropolitan WWTP. Environmental Progress,
2001, 20, No. 3, 212.
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