impact of aggressive environment on ......structure, corrosion of steel, and decrease in service...

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International Journal of Civil Engineering and Technology (IJCIET)

Volume 8, Issue 9, September 2017, pp. 777–788, Article ID: IJCIET_08_09_087

Available online at http://http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=8&IType=9

ISSN Print: 0976-6308 and ISSN Online: 0976-6316

© IAEME Publication Scopus Indexed

IMPACT OF AGGRESSIVE ENVIRONMENT ON

CONCRETE – A REVIEW

Venkata Rambabu V

Research Scholar, SCALE, VIT University, Vellore, India

Amit B Mahindrakar

Professors, SCALE, VIT University, Vellore, India

ABSTARCT

The present day construction industry needs an environmental friendly material

which should with stand its material properties through outs its estimated life span.

The material should be aesthetically pleasing, maintain balance in ecology of

environment in order to take health care of it and wastages should be minimized.

Concrete is one such material which full fill all the needs and lots of research has

been going on for predicting its behavior in various environmental conditions.

Concrete may be affected by the presence of pollutants in the environment such as

carbon di-oxide, NOX, oxides of sulpher and suspended particulate matter.

At present concrete is gaining special importance due to its ability to resist severe

environmental conditions such as marine environment, harsh environment (high &

elevated temperature), high humid regions, sulphate rich environment, acidic

environment, alkaline environment, sewer environment, freeze & thaw Cycles, and

et.,.

These environments lead to deterioration of concrete by effecting plastic

shrinkage, strength loss at later ages, decrease in compressive strength, pore

structure, corrosion of steel, and decrease in service life i.e., life expectancy and

durability.

To overcome these problems concrete made with different types of admixtures in

ordinary Portland cement like Fly-ash, Granulated Blast furnace Slag, Rice husk ash

and Silica fume, or Pozzolana cements, slag cements, pumice stone concrete and low

calcium flyash based concrete will serve.

Key words: Portland slag cement, Concrete, Marine environment.

Cite this Article: Venkata Rambabu V, Amit B Mahindrakar, Impact of Aggressive

Environment on Concrete – A Review. International Journal of Civil Engineering and

Technology, 8(9), 2017, pp. 777–788.

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=9

Impact of Aggressive Environment on Concrete – A Review


1. INTRODUCTION

The present day construction industry needs an environmental friendly material which should

with stand its material properties through outs its estimated life span. The material should be

aesthetically pleasing, maintain balance in ecology of environment in order to take health care

of it and wastages should be minimized. Concrete is one such material which full fill all the

needs and lots of research has been going on for predicting its behavior in various

environmental conditions.

Concrete may be affected by the presence of pollutants in the environment such as carbon

di-oxide, NOX, oxides of sulpher and suspended particulate matter.

At present concrete is gaining special importance due to its ability to resist severe

environmental conditions such as marine environment, harsh environment (high & elevated

temperature), high humid regions, sulphate rich environment, acidic environment, alkaline

environment, sewer environment, freeze & thaw Cycles, and et.,.

2. EFFECT OF AIR TEMPERATURE

Concrete exposed to various weather conditions such as temperature which is going to vary

seasonally will affect the physical and mechanical properties of concrete, Marine environment

is said to be harsh because its high temperature varying between 20oC to 54

oC accompanied

by high humidity 80% to 90% together with the presence of chloride, Steel corrodes under

marine environment due to coupled effect of high humidity and high temperature which

occurs often.

Concrete made under different environmental exposure conditions at time of casting is

going to affect the plastic shrinkage of concrete, compressive strength and pulse velocity.

Experimental investigations done by Abdulla A Almsallam (2001) states that the compressive

strength of concrete is going to decrease when concrete cast at elevated temperatures. High

pulse velocity value was observed in concrete cast at 30oC than concrete cast at 45

oC due to

having less pore volume in concrete cast at 30oC than concrete cast at 45

oC.

3. EFFECT OF WIND VELOCITY

The deterioration of a material depends on how and to what extent it interacts with its

surroundings. The outdoor environment if considered in terms of sunshine, temperature,

rainfall and wind, varies widely in duration, intensity and sequence. As far as the durability of

materials is concerned, weight should be given to severe climatic conditions and depends on

the confidence level required in the performance of the material, but in general it is the time-

averaged climatic factors which should be considered. A marine environment is the place

where concrete becomes wet with seawater. This could happen to concrete submerged under

water, in a tidal zone, in a splash zone, or at any place inland where wind could carry the salt

water spray.

4. EFFECT OF WATER QUALITY

The concomitant presence of sulfate and chloride ions in marine environments causes

deterioration of reinforced concrete structures and reinforcement corrosion. The reaction of

the concrete with the sulfate ions in marine environments is similar to that of sulfate ions in

non-marine environments, but the effects are different due to the presence of chloride ions in

the former. The sulfate attack in marine environment gives rise to expansive ettringite,

gypsum, and brucite and sometimes is associated with calcite formation. The sulfate

permeation may be controlled by: increasing compactness, low water cement ratio, properly

Venkata Rambabu V, Amit B Mahindrakar


designed and constructed joints, proper curing, surface treatment, and use of precast concrete

in place of cast-in-situ concrete. Limitation on C3A content is not the ultimate answer to the

problem of sulfate attack.The beneficial effect of precasting in marine environments was

noticeable in all the three types of plain and blended cements. In some of the cases, the losses

have been reduced to even more than 40% in simulate precast situations.

The reports on the results of an experimental investigation carried by Sunil Kumar (2000)

states that effects of the quality of mixing water effects initial curing on the strength of

concrete in marine environments were investigated by considering different levels of fly ash

replacement and cement type. Concrete specimens made with plain cements, of different

brands of cement, and blended cements made with fly ash were exposed to marine

environments for a period of 1 year. The performance of these cements in concrete was

evaluated by reduction in compressive strength. Results of this study showed that the use of

pre-casting in place of casting-in-situ mitigates the effect of marine environments on concrete

specimens considerably.

5. EFFECT OF CURING

Curing and environmental conditions have significant effects on the physical and mechanical

properties of concrete. Curing conditions can be changed by the engineers on construction as

regarding the changes in ambient conditions. Plastic shrinkage cracks, insufficient strength at

later ages, durability loss problems can be seen frequently as a result of insufficient curing.

Concretes exposed to seasonal fluctuations can be more vulnerable due to these problems.

When placing concrete in a dry, hot weather climate, precautions are needed to prevent rapid,

early drying of the concrete surface. Studies of Niyaji ugur kockal et al., (2007) says adding

silica fume (10% of cement weight) to concrete mix greatly reduces the 3-year drying

shrinkage, the stress due to shrinkage strain, and the rate of first month drying shrinkage of

concrete. This is true whether concrete is subjected to controlled laboratory or hot-dry field

curing conditions.

The experimental work done by P.Castro et al., (2001) on Concrete cylinders with an

embedded reinforcing bar and different water/cement ratios which were cured for different

periods and then exposed in a salt spray chamber (according to 180-9227). Cylinders from the

same batches were also exposed to a marine atmosphere for 24 months at a location 50 m

from the shoreline. In both exposures the corrosion rate, the corrosion potential and the

chloride content close to the reinforcing bars were monitored as a function of the exposure

time, in order to obtain information about the corrosion kinetics. These data allowed us to find

relationships between exposure time in marine natural weathering (field tests) and in a salt

spray chamber (accelerated tests). Therefore, rapid surveys (in periods of 30-45 days) of the

type of reinforced concrete evaluated here can be made using 7 days of curing. The results

showed that the salt spray chamber tests modified the corrosion kinetics of reinforced

concretes with curing times below 7 days.

6. EFFECT OF FREEZE AND THAW CYCLES

In construction of buildings the main material has long been the concrete. Therefore,

production of concrete is becoming very crucial if the buildings are of critical importance

such as hospital, nuclear power station, etc. The barite is known to be an ideal material to

shield g-rays, and the difficulties of finding sufficient deposits direct it to be used within

concrete as an aggregate. However, the freezing–thawing cycles may damage the

microstructure of concrete and thus it may affect the capability of concrete against radiation

shielding. C. Basyigit et al.,(2006) has done some experimental and theoretical works



performed on the linear attenuation coefficients for different types of concretes. It was noticed

that the linear attenuation coefficients decreased with F–T cycles for all concrete types and

also different effect observed for different w/c ratio and different aggregate.

Today quality of concrete and mortars contain in the most cases one or more admixtures.

Concrete and mortar admixtures are designed substances with aim of influencing their fresh

and hardened properties by their physical and chemical action. The research work of U.

Maeder, et al., said in the case of fresh concrete the flow, the cohesiveness and setting

behavior, are controlled but also the hardened concrete such as strength, impermeability,

shrinkage or, or freeze thaw resistance can be positively influenced by the use of concrete

admixtures.

Conventional cold-weather concreting is expensive and very energy inefficient. Common

practice requires artificial heating of the raw materials and the surrounding environment to

create suitable curing conditions for normal concrete. Antifreeze concrete is a new approach

to cold-weather concreting without the need for artificial heating. This saves time, money, and

energy. The antifreeze concrete technology has been proven in numerous full-scale field

demonstrations and is compatible with current concrete construction practices. Laboratory

studies of Lynette A. Barna et al., (2011) established the practicality of using antifreeze

concrete and developed the tools to mix and cure concrete in subfreezing temperatures. Eight

candidate antifreeze formulations were developed in the laboratory and subjected to initial

screening tests that showed they were capable of being workable, entraining air, and meeting

the design freezing point. Performance testing showed that the strength gain when cured at -

4°C is as good as conventional concrete cured at +5°C and that antifreeze mixtures can be

made durable. High dosages of chemical admixture used in antifreeze concrete mixtures were

not harmful to the concrete. It is recommended that agencies conduct testing on their own to

become familiar with the antifreeze mixtures before widespread use.

7. EFFECT OF HARSH ENVIRONMENT

The diffusion of chloride is influenced by many factors including the composition of the

concrete and its porosity. The study of A.K.Tamimi et al., (2008) Specifies Since aggregates

represent around 75% of the volume of concrete in a typical concrete mix, aggregate

properties play a significant role in chloride diffusion and durability of concrete structures that

addition of silica fume (SF) and other durability enhancing materials such as fly ash (FA) and

GGBS in certain percentages can increase the durability of concrete drastically.

8. EFFECT OF SEA WATER ABSORPTION

A marine environment is a place where concrete becomes wet with seawater. This could

happen to concrete submerged under water, in a tidal zone, in a splash zone, or at any place

inland where wind could carry the salt water spray. The major characteristics of environment

are hot marine environment exceeds 500c and subjected sea water or through ground water,

water laden atmosphere for structures depending on humidity, direction and speed of wind.

The use of epoxy resins in the building industry is increasing rapidly. The advantages of

epoxies include adhesion, versatility, chemical resistance, low shrinkage, rapid hardening and

moisture resistance. They may be used as protective coatings to protect concrete against

severe environments, as decorative coatings, as skid-resistant coatings, as grouting and repair

materials, as adhesives for cementing various materials to hardened concrete, and as a

bonding medium between fresh and hardened concrete. Epoxies are also used in producing

epoxy-modified concrete and in protecting reinforcing bars against corrosion. The use of

epoxy resins in the repair of concrete members depends on the size of the crack. Epoxy may



be applied by injection for very small cracks, by grouting and pumping for moderate cracks,

and as epoxy mortar for large cracks. The experimental work of Moetaz El-Hawary et

al.,(1998) Says Deteriorated concrete is usually repaired using some type of epoxy resin.

The method of application of epoxy depends on the size of the crack and level of

deterioration. Epoxy may be introduced as mortar for wide cracks, by grouting for medium

size cracks, and by injection for small cracks. Repaired structures are usually subjected to the

same environmental conditions that caused their deterioration in the first place, which

necessitates the study of the performance of epoxy-repaired concrete.

9. EFFECT OF W/C RATIO

W/C ratio is one of the factor which govern the workability of concrete. W.Chalee et al.,

(2007) studied effect of W/C ratio on covering depth required against the corrosion of

embedded steel of fly ash concrete in marine environment up to 4-year exposure. The chloride

penetration of fly ash concrete was comparatively low and decreased with the increasing of

fly ash content. The increase of fly ash replacement and the decrease of W/C ratio could

reduce the covering depth required for the initial corrosion of the steel bar. Interestingly, fly

ash concretes with 35% and 50% cement replacement and having W/C ratio of 0.65 provided

better corrosion resistance at 4-year exposure than the control concrete with W/C ratio of

0.45. In addition, the covering depth of concrete with compressive strength of 30 MPa (W/C

ratio of 0.65) could be reduced from 50 to 30 mm by the addition of fly ash up to 50%.

The sulfate permeation may be controlled by: increasing compactness, low water cement

ratio, properly designed and constructed joints, proper curing, surface treatment, and use of

precast concrete in place of cast-in-situ concrete.

10. EFFECT OF SOIL BELOW GROUND IN COASTAL AREAS

Soil water may contain up to l.0 percent total sulfate salts (about 0.65 to 0.80 percent S04) . In

isolated locations, and also if concrete resting on wet sulfate-bearing soils is subject to surface

drying, the sulfate salt concentrations in the interior may exceed l.0 percent and, in rare

instances, may be 5.0 percent or more.

The research carried out by G.L.Kalousk. et al., (1972) says concretes for long-time

survival in a sulfate environment should be made with high quality pozzolans and sulfate-

resisting cement. The pozzolans should not increase significantly, but preferably decrease, the

amount of water required cement to be used in making sulfate-resisting concrete with

pozzolan of proven performance should have a maximum C3A content of 6.5% and maximum

C4AF content of 12%.

11. EFFECT OF CHLORIDE

The performance of concrete exposed to below ground conditions in a coastal area. The

concrete specimens were prepared with varying water/cement ratio, cement content, and

polymer/epoxy additions and varying consolidation efforts prior to exposure to below ground

conditions in a coastal area for more than four years. The performance of the concrete

specimens exposed to the highly concentrated chloride and sulfate environment was evaluated

by Maher A. Bader(2003) measuring the chloride diffusion and reduction in compressive

strength due to sulfate attack. Results indicated that the mix design parameters, such as

water–cement ratio and cement content, significantly affected both the chloride diffusion and

the sulfateresistance of concrete. Similarly, the level of consolidation and the period of curing



influenced the performance of concrete in the aggressive environment. Further, the

performance of latex and epoxy modified concrete was better than that of polymer concrete.

12. EFFECT OF SULPHATES

External sulfate attack on cement-based materials has been a key durability issue and a

subject of extensive investigation for many decades. Dissolved sulfate salts can enter into

chemical reactions with cement-based materials causing expansion, cracking and spalling,

and/or softening and disintegration. The classical form of sulfate attack involves alkali

sulfates such as sodium sulfate (Na2SO4) which reacts with portlandite (CH), monosulfate

and unreacted C3A to form gypsum (CSH) and ettringite (C6AS3H32), which can cause

expansion, cracking, and deterioration of concrete.

( ) ( ) ( )

The above equations indicate the possible decomposition of CH and C–S–H leading to

softening along with expansion. Hydroxyl ions (OH−) may leach away to the surrounding

solution resulting in a pH increase. In the case of alkali sulfates, alkali ions such as Na+ can

migrate to the pore solution, which increases the risk of alkaliaggregate reaction. The study of

M.T.Bassuoni et al.,(2009) says Hydrated pozzolanic pastes with limited portlandite content

and sulfate resistant cements with low C3A content (less than 8%) have a high resistance, but

are not completely immune to alkali sulfates.

The classical idea of sulphate attack considering the migration of sulphate ions from

ground or river water into concrete with subsequent phase transformation and damage has not

been confirmed. This kind of exposure was found to be rare and no serious deterioration has

been observed in connection with it. However, concrete is liable to be destroyed when in

contact with sulphide bearing environments or if intimately mixed with gypsum. The

experimental work done by F. Bellmann et al., (2012) says disintegration and serious

expansion and suggested requiring immediate repair. Upon the contact of concrete with

sulphate containing environments, a diffusion of sulphate and potentially of other ions in the

hardened cement paste takes place. Some of the phases in the microstructure are sensitive to

an interaction with sulphate. Calcium hydroxide reacts with sulphate ions to gypsum, AFm

phases are converted to ettringite, and C–S–H is potentially transformed into thaumasite. All

of these reactions induce a modification of the microstructure of the hardened cement paste.

Most often, expansion and micro-cracking are observed, although softening and disintegration

have been reported as well. In order to avoid these deterioration processes, mix design

properties such as water/cement-ratio and cement content are modified and sulphate-resisting

cements or binders are used. Susceptibility is reduced by restricting the amount of the clinker

phase C3A in the cement and by adding mineral admixtures such as blast furnace slag and

coal fly ash.

13. EFFECT OF POZZALANAS

Based on research study by G.L.Kalousk. et al., (1972) Fly ash, pumice, and two calcined

products markedly improved sulfate resistance. Concretes for long-time survival in a sulfate

environment should be made with high quality pozzolans and sulfate-resisting cement. The

pozzolan should not increase significantly, but preferably decrease, the amount of water

required Cement to be used in making sulfate-resisting concrete with pozzolan of proven

performance should have a maximum C3A content of 6.5 percent and maximum C4AF content

of 12 percent.



The investigations of S. Muralidharan et al.,(2005) carried out for the estimation of free

chloride and total chloride contents in different types of concretes, namely ordinary Portland

cement (OPC), Pozzolana Portland cement (PPC) and Portland slag cement (PSC). Macro-cell

concrete specimens were cast and subjected to severe alternate wetting and drying cycles of

10-months exposure. Concrete core samples were collected from the above specimens under

different depths, namely20, 40 and 60 mm. Six extraction methods for determination of free

chloride and two extraction methods for determination of total chlorides in concrete have been

carried out. Boiling water method was found to be a suitable for the determination of free

chloride contents in concrete. As the depth increases the amount of chloride ion decreases.

Filtration method is found to be not suitable for the determination of chloride ion in concrete.

There is no quick method for determining the chloride concentration in concrete either in the

field or in laboratory. Water-soluble chloride alone is a good indicator of the concentration of

chloride ion in concrete. ISE method appears to be most convenient but it requires lot of

calibration before analysis.

As the depth of concrete increased, the amount of chloride ions decreased. The amount of

free chloride contents in OPC concrete is more when compared to PPC and PSC concretes.

14. EFFECT OF ADMIXTURES

The study of Lynette A. Barna et al., (2011) says conventional cold-weather concreting is

expensive and very energy inefficient. Common practice requires artificial heating of the raw

materials and the surrounding environment to create suitable curing conditions for normal

concrete. Antifreeze concrete is a new approach to cold-weather concreting without the need

for artificial heating. This saves time, money, and energy. The antifreeze concrete technology

has been proven in numerous full-scale field demonstrations and is compatible with current

concrete construction practices. A laboratory study established the practicality of using

antifreeze concrete and developed the tools to mix and cure concrete in subfreezing

temperatures. Eight candidate antifreeze formulations were developed in the laboratory and

subjected to initial screening tests that showed they were capable of being workable,

entraining air, and meeting the design freezing point. Performance testing showed that the

strength gain when cured at - 4°C is as good as conventional concrete cured at +5°C and that

antifreeze mixtures can be made durable. High dosages of chemical admixture used in

antifreeze concrete mixtures were not harmful to the concrete. It is recommended that

agencies conduct testing on their own to become familiar with the antifreeze mixtures before

widespread use.

The work done by U. Maeder, et al., said in the present day quality of concrete and

mortars contain in the most cases one or more admixtures. Concrete and mortar admixtures

are designed substances with aim of influencing their fresh and hardened properties by their

physical and chemical action. For example, in the case of fresh concrete the flow, the

cohesive ness and setting behavior, are controlled but also the hardened concrete such as

strength, impermeability, shrinkage or, or freeze thaw resistance can be positively influenced

by the use of concrete admixtures.

The study of Venu M et al., (2009) says concrete is the most common building material.

Attention is being paid to develop the specialized concrete varieties, to enhance the service

life of the buildings, and to provide satisfactory performance under aggressive environments.

At present, cement concrete practice is under-going a rapid and phenomenal development in

India. The concrete mix with an addition of appropriate chemical admixtures often improves

its plastic properties such as workability, pumpability, cohesion and adhesion. Addition of

admixtures will also reduce the bleeding of concrete and gives fine surface finish. An attempt



has been made to investigate the strength parameters of concrete design mix M25 with

admixtures. Three different types of admixtures CONPLAST SP430, SIKAMENT NN and

SAVEMIX SP111 are considered in his study and a comparative analysis is made. The

ultimate goals of using admixtures are to improve one or more aspects of concrete

performance or to maintain the same level of performance

15. EFFECT OF VARIATION IN POROSITY

The study of Pendfei huang et al.,(2005) says one of the main causes for deterioration in

concrete structures is the corrosion of concrete due to its exposure to harmful chemicals that

may be found in nature, such as in some ground waters, industrial effluents, acid rain, acid

mist, and seawater. The chlorides and sulfates belong to the most aggressive chemicals that

affect the long-term durability of concrete structures. The degradation of a porous medium

depends on two consecutive phenomena: (1) material transport by diffusion, resulting from

concentration gradients between the solid interstitial solution and the aggressive solution, and

(2) dissolution-precipitation chemical reactions, induced by the concentration variations

reached in the diffusion process. In the presence of waters containing chlorides, cement mass

is chemically exposed to the pH of the incoming water that produces a progressive

neutralization of the alkaline nature of the cement paste, removing alkalies and dissolving

portlandite and CSH gel (dissolution produces the increase in porosity and permeability). In

the presence of Cl-, The release of calcium from Ca(OH)2 and CSH could be controlled by

the precipitation of alteration solid phases. The chloride dissolved in waters speeds up the rate

of the leaching of portlandite and thus increases the porosity of concrete, and then leads to the

loss of stiffness and strength. The degradation rate of the concrete exposing in harmful

chemicals depends mainly on the fraction of the chemicals in water, the exposure time, and

the chemical resistance of concrete.

This phenomenon confirmed that the mass loss of the normal strength concrete is more

serious than that of the highstrength concrete. It was found that the degree of the corrosion

damage decreases with increasing depth. A deteriorating effect of HCl corrosion is highest at

the surface of the samples.

16. EFFECT OF ALKALINE MEDIUM

Sunil K.Tengli (2009) an experimental research program is undertaken to understand

thoroughly the behaviour to low calcium fly ash based Geopolymer concrete. Low calcium

class F fly ash obtained from Raichur Thermal Power Plant is used as the Base material. A

combination of sodium silicate solution (Na2 SiO3) and sodium hydroxide solution (NaOH) is

chosen as the alkaline liquid. Sodium based solutions are chosen because they are cheaper

than Potassium based solutions. Combined aggregates(Group I) with three different sizes of

20mm(15%), 10mm(20%) and 6mm(35%) and fine aggregates(30%) passing 100% from

2.36mm sieve. In Group II, 10mm (35%) and 6mm (35%) and fine aggregate (30%) passing

100% from 1.18mm sieve. In Group III, only 6mm (70%) with fine aggregate (30%) passing

100% from 1.18 sieves are chosen.Two types of heat curing are used in this study i.e. dry

curing and Steam curing. Numbers of trial mixtures of geopolymer concrete are manufactured

and test specimens in the form of 100mm*100mm*100mm cubes and 100mm*200mm

cylinders are made. Suitable mix proportions are developed by varying Sodium Hydroxide

concentration and/or ratio of Sodium Silicate to Sodium Hydroxide solution and to study the

geopolymer concrete properties such as the compressive and indirect tensile strength, and the

workability of fresh concrete.



The study of Raquel R.Aveldano et al.,(2011) says when corrosion of reinforced concrete

structures takes place, the transformation of metallic iron into oxide is accompanied by a

volume increase that can reach up to 600% of the volume of the original iron, depending on

the oxidation state . This increase in volume of the oxides is the main cause of the expansion

and cracking of the concrete. That occurs because these products initially stay on the surface

of the bar, trying to occupy the empty spaces of the adjacent concrete pore structure. Later,

they press on the cover concrete, because their volume is greater than that of the basic metal,

and cracks are generated when its tensile stress limit is exceeded. These cracks begin on the

surface of the bar but soon reach the surface of the concrete cover. This cracking develops

longitudinally throughout the bars, and looks different from the cracking originated by

bending stress, which is frequently perpendicular to the bars. The appearance of cracks can

accelerate the corrosion processes while the chemical and/or electrochemical conditions of the

steel–concrete interface are modified . characterizing cracking on concrete beams produced

by corrosion of steel reinforcement exposed to different atmospheres. These environmental

conditions were obtained by means of two electrolytic media: one alkaline, simulating the

situation that occurs in an industrial environment, with beams exposed to a saturated solution

of Calcium Hydroxide; and another with beams exposed to a Sodium Chloride solution,

simulating de-icing or a marine environment. Test samples in reduced lab scale were tested

too, in order to identify the different corrosion products generated in each case (and their

influence on concrete cracking). Observation showed that the consistency of these products

and the variation of the concrete consistency with regard to the environment employed,

govern the cracking process.

17. CONCRETE EXPOSED TO SEWER ENVIRONMENT

Cement concrete is extensively used in the construction of buildings, transportation facilities

and sewage systems. Cement concrete is highly alkaline and can easily deteriorate under

acidic environments. Many municipalities are discovering that cement concrete structures in

the wastewater collection and treatment facilities, such as wet wells, holding tanks, manholes,

and sewer pipelines, are subjected to microbial-induced deterioration and the concrete is

degraded with time. The sulfuric acid-producing bacteria found on sewer crowns thrive at

low pH values which are inhibitory to most competitors. To protect concrete facilities from

sulfuric acid attack, coating the concrete is one method now being adopted.

The work carried out by Pendfei huang et al.,(2005) says one of the main causes for

deterioration in concrete structures is the corrosion of concrete due to its exposure to harmful

chemicals that may be found in nature, such as in some ground waters, industrial effluents,

acid rain, acid mist, and seawater. The chlorides and sulfates belong to the most aggressive

chemicals that affect the long-term durability of concrete structures. The degradation of a

porous medium depends on two consecutive phenomena: (1) material transport by diffusion,

resulting from concentration gradients between the solid interstitial solution and the

aggressive solution, and (2) dissolution-precipitation chemical reactions, induced by the

concentration variations reached in the diffusion process. In the presence of waters containing

chlorides, cement mass is chemically exposed to the pH of the incoming water that produces a

progressive neutralization of the alkaline nature of the cement paste, removing alkalies and

dissolving portlandite and CSH gel (dissolution produces the increase in porosity and

permeability). In the presence of Cl-, The release of calcium from Ca(OH)2 and CSH could be

controlled by the precipitation of alteration solid phases. The chloride dissolved in waters

speeds up the rate of the leaching of portlandite and thus increases the porosity of concrete,

and then leads to the loss of stiffness and strength. The degradation rate of the concrete



exposing in harmful chemicals depends mainly on the fraction of the chemicals in water, the

exposure time, and the chemical resistance of concrete.

This phenomenon confirmed that the mass loss of the normal strength concrete is more

serious than that of the highstrength concrete. It was found that the degree of the corrosion

damage decreases with increasing depth. A deteriorating effect of HCl corrosion is highest at

the surface of the samples.

The research carried out by C.Vipulanandan et al.,(2005) says polyurethane-based

coatings are used to protect concrete facilities against corrosive environments.

The study of R.E.Melchers et al.,(2008) says for existing reinforced concrete structures

exposed to saline or marine conditions, there is an increasing engineering interest in their

remaining safety and serviceability. A significant factor is the corrosion of steel

reinforcement. At present there is little field experience and other data available. This limits

the possibility for developing purely empirical models for strength and performance

deterioration for use in structural safety and serviceability assessment. An alternative

approach using theoretical concepts and probabilistic modeling is proposed herein. It is based

on the evidence that the rate of diffusion of chlorides is influenced by internal damage to the

concrete surrounding the reinforcement. This may be due to localized stresses resulting from

external loading or through concrete shrinkage. Usually, the net effect is that the time to

initiation of active corrosion is shortened, leading to greater localized corrosion and earlier

reduction of ultimate capacity and structural stiffness. The proposed procedure is applied to

an example beam and compared to experimental observations, including estimates of

uncertainty in the remaining ultimate moment capacity and beam stiffness. Reasonably good

agreement between the results of the proposed procedure and the experiment was found.

The work done by A.K.Parande et al., (2011) says Wastewater treatment plant consists of

pipe lines and lift stations. These plants consist of concrete pipes, manholes, pump stations,

interceptors and wet wells. Entire wastewater (WW) system is forced to chemical attack due

to the presence of sulphate and acid available in WW. It leads to the damage in the interior

wall or structure of a sewer pipe and lift station. A concrete structure when exposed to

different environments, the life of the structure is drastically reduced. Main cause of the

deterioration is corrosion or erosion. The defective structures are replaced periodically which

leads to indirect loss in the national growth. In other words, the failure of these structures may

lead to invest more on the repair and rehabilitation. In this study, the strength of the concrete

in various environments has been investigated using different techniques such as compressive

strength, flexural test, rapid chloride permeability, weight loss measurements, linear

polarization and open circuit potential. Microbiological examinations were also analyzed.

Two types of cement namely ordinary Portland Cement (OPC) and Portland Pozzolana

Cement (PPC) with one mix ratio were used for complete study. Concrete specimens exposed

in three environments namely: normal water (NW Potable water), domestic sewage water

(DSW) and textile wastewater (TWW). From the results, it is observed that PPC exposed in

different media shows better performance than OPC in both mechanical and electrochemical

studies.

18. CONCLUSIONS

Based on the present study we can conclude weathering agents will influence the fresh and

hardened properties of concrete and an essential research has to be done to enable concrete to

fill its role. Water cement ratio is one of factor dominating the performance of concrete.

Ordinary Portland can be replaced by Portland pozzolana cements but it needs study. Epoxy



resins may be used to come over the problems of corrosion but it needs study. Addition of

admixtures is needed to meet the demands. Reduction pores in concrete will serve better in

environment. Type of curing adopted in marine regions will play a lead role for sustainability

of concrete.

REFERENCES

[1] A.K. Tamimi et al., Prediction of longterm chloride diffusion of concrete in harsh

environment, “Construction and building materials”, Vol-22, 2008, 829-836.

[2] A.K.Parande, et al., Environmental effects on concrete using ordinary and Portland

pozzolana Portland cement, “Construction and building materials”, vol-25,2011,288-297.

[3] A.Ranganathan and R.malathy, Durability of alkali activated geopolymer concrete against

sulphuric acid attach, ”ACSGE-2009”, Oct 285-27, BITS Pilani, India.

[4] Abdulla A Almusallam, Effect of environmental conditions on the properties of fresh and

hardened concrete, “Cement and Concrete composites”, Vol-23, 2001, 353-361.

[5] Bulu Pradhan, B.Bhattacharjee, Performance evalution of rebar in chloride contaminated

concrete by corrosion rate,” Construction and building materials”, Vol-23, 2009, 2346-

2356.

[6] C. Vipulanandan, J.liu, Performance of polyurethane-coated concrete in sewer

environment, “Cement and concrete research”, Vol-35, 2005, 1754-1763.

[7] C.Basyigit et al., The effect of freezing – thawing (F-T) cycles on the radiation shielding

properties of concretes, “Building and environment”, Vol-41, 2006, 1070-1073.

[8] F.Bellmann et al., Field performance of concrete exposed to sulphate and low PH

conditions from natural and industrial sources, “Cement and concrete composites “, vol-

34, 2012, 86-93.

[9] F.Girardi et al., Resistance of different types of concretes to cyclic sulphuric acid and

sodium sulphate attack, “Cement and concrete composites “, vol-32, 2010, 595-602.

[10] G.L.Kalousk. et al., Concrete for long-time service in sulphate environment, “Cement and

concrete research”, Vol-2, 1972, 79-89.

[11] Giri Prasad .G et al., Assessment of self compacting concrete immersed in acidic

solutions,”ACSGE-2009”, Oct 285-27, BITS Pilani, India.

[12] H.Toutanji et al., Chloride permeability and impact resistance of poly propylene-fiber-

reinforced silica fume concrete, “Cement and concrete Research” Vol-28, 1998, 961-968.

[13] Hsien-Kuang Liu et al., Effect of sea water on compressive strength of concrete cylinders

reinforced by Non-adhesive wound hybrid polymer composites, “ Composites science and

technology” Vol-62, 2002, 2131-2141.

[14] Lynette A. Barna et al., Energy efficient approach to cold-weather concreting, ”Journal of

materials in civil engineering(ASCE)”, NO2011, 1544-1551.

[15] M. M Abd-El-Razek, S.A. Abo-El-Enein, Moisture performance through fresh concrete at

different environmental conditions, “Cement and concrete research” Vol-29, 1999, 1819-

1825.

[16] M.T. Bassouni, M.L.Nehedi, Resistance of Self consolidating concrete to sulphuric acid

attack with consecutive PH reduction, “ Cement and concrete research” vol-37, 2007,

1070-1084.

[17] M.T. Bassuoni and M.L.Nehdi, Durability of self-consolidating concrete to sulphate attach

under combined cyclic environments and flexural loadings, “ Cement and concrete

Research”, Vol-39, 2009, 206-226.

[18] Maher A. Bader, Performance of concrete in coastal environment,” Cement and concrete

composites”, Vol-25, 2003, 539-548.

[19] Martin O’Connel et al., Performance of concrete incorporating GGBS in aggressive waste

water environments, “Construction and building materials”, Vol-27, 2012, 368-374.



[20] Michael henry et al., Balencing durability and environmental impact in concrete

combining Low-Grade recycled aggregates and mineral admixtures, “Resources,

Conservation and Recycling”Vol-55, 2011, 1060-1069.

[21] Moetaz El-Hawary et al., Effect of sea water on Epoxy-repaired concrete, “Cement and

Concrete composites”, Vol-20, 1998, 41-52.

[22] Moetaz El-Haway et al., Performance of epoxy repaired concrete in marine environment,

“cement and concrete research”, Vol-30, 2000, 259-266.

[23] P.Castro et al., Corrosion of reinforced concrete in a tropical marine environment and in

accelerated tests, “Construction and Building materials, Vol-11, 1997, 75-81.

[24] R.Malheiro et al., Influence of mortar rendering on chloride penetration into concrete

structures,” Cement and concrete composites”, Vol-33, 2011, 233-239.

[25] Raquel R.Aveldano et al., Characterization of concrete cracking due to corrosion of

reinforcements in different environments, “Construction and building materials”, Vol-25,

2011, 630-637.

[26] S.Muralidharan et al., Studies on the aspects of chloride ion determination in different

types of concrete under macro-cell corrosion conditions, “Building and environment”,

Vol-40, 2005, 1275-1281.

[27] Sunil K.Tengli, and Kalappa M.S, Effect of variation in concentration of alkaline solutions

on the behavior of geopolymer concrete, “ACSGE-2009”, Oct25-27,BITS Pilani, India.

[28] Sunil kumar, Influence of water quality on the strength of plain and blended cement

concretes in marine environments, “Cement and concrete research” Vol-30, 2000, 345-

350.

[29] Venu M et al., Effect of Admixtures in concrete mix design, ”ACSGE-2009”, Oct 285-27,

BITS Pilani, India.

[30] Vesa penttala et al., Stress and strain state of concrete during freezing and thawing cycles,

“Cement and concrete research”, Vol-32, 2002, 1407-1420.

[31] W.chalee et al., Effect of W/C ratio on covering depth of flyash concrete in marine

environment, “Construction and building materials”, Vol-21, 2007, 965-971.

[32] W.Chalee et al., Utilization of fly ash concrete in marine environment for long term

design life analysis, “Materials and design”, Vol-31, 2010, 1242-1249.

[33] Yousef A. Al-salloum et al., Creep effect on the behavior of the concrete beams reinforced

with GFRP bars subjected to different environments, “Construction and building

materials”, Vol-21, 2007, 1510-1519.

[34] Ch. Srinivasarao, SS. Asadi and M. Kameswararao Study of High Grade Portland Slag

Cement Concrete Containing Granulated Blast Furnace Slag as Fine Aggregate.

International Journal of Civil Engineering and Technology , 8(5), 2017, pp. 100–112.

[35] K. Naga Sahadeva Reddy and Dr. C. Raja Gopal Reddy , Study On Strength Characteristic

of Concrete Masonry Units U sing Recycled Concrete Aggregates. International Journal

of Civil Engineering and Technology , 8(3), 2017, pp. 201–209

impact of aggressive environment on ......structure, corrosion of steel, and decrease in service...

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