Environmental factors affecting durability of concrete

1. DURABILITY OF CONCRETE
Presented by : Arun Sharma
Roll no.: 140134
Class : D4 CE (B1)

2. CONTENTS
• INTRODUCTION
• CONSEQUENCES OF INADEQUATE DURABILITY
• FACTORS GOVERNING DURABILITY
• LITERATURE REVIEW
• IS 456:2000 RECOMMENDATIONS
• DISCUSSION
• REFERENCES

3. DURABILITY
• Durability of structure, component etc. is its capability to maintain a minimum performance
level over a specified time when exposed to degradation environment.
• Durability of concrete is its ability to resist weathering action, chemical attack, or any other
process of deterioration
• Performances are the measures of fulfillment of functions.
• Performance varies with time and degradation is gradual decrease of performance with time.

4. SERVICE LIFE
• Concrete is not maintenance free.
• It is produced at the expense of energy.
• Concrete degrades with time.

5. CONSEQUENCES OF INADEQUATE DURABILITY
• Loss of strength of concrete
• Loss of serviceability
• Unpleasant appearance
• Danger to persons and property
• Expensive repair costs
• Poor perception of concrete as a material
• Reduction of service life
• External agencies like weathering, attack by natural or Industrial liquids, Gases, bacterial
Growth etc.
• Ingression of moisture/air facilitating corrosion of steel and cracking concrete cover.

6. FACTORS AFFECTING DURABILITY
6
DURABILITY
The Concrete System Aggressiveness of the
Environment
Materials Process Physical Chemical
• Binder type
• Binder content
• Aggregates
• Admixture
• Mix design
• Mixing
• Transporting
• Compaction
• Curing
• Temperature
• workmanship
• Abrasion
• Freezing and
Thawing
• Sulphate Attack
• ASR
• Chloride Attack

7. • SOME OF THE MAJOR DURABILITY PROBLEMS ARE:
• FREEZE AND THAW
• ALKALI -SILICA REACTION
• SULPHATE ATTACK

8. FREEZING AND THAWING:
• Deterioration of concrete from freeze thaw actions may occur when the concrete is critically
saturated, which is when approximately 91% of its pores are filled with water.
• When water freezes to ice it occupies 9% more volume than that of water.
• As the seasons pass, concrete goes through the process of freezing and thawing resulting in
repeated loss of concrete surface
• With the addition of an air entrainment admixture, concrete is highly resistant to freezing
and thawing.

9. https://www.google.co.in/search?q=freezing+and+thawing+of+concrete&rlz=1c1chbf_enin765in765&source=lnms&tbm=isch&sa=x&ved
=0ahukewii0bbog9rwahwmoo8khfmqbwcq_auicigb&biw=1366&bih=613#imgrc=rtqjv7jre-kt7m:
FREEZING AND THAWING:

10. Source:https://civildigital.com/freeze-thaw-damage-concrete-effects-preventive-measures/
Pavement damage due to freeze thaw cycles

11. ALKALI-SILICA REACTION
• The alkali–silica reaction (ASR) is a reaction which occurs over time in concrete between
the highly alkaline cement paste and reactive non-crystalline (amorphous) silica, which is
found in many common aggregates.
• ASR is known as the “cancer of concrete” as once ASR is initiated, it could be
deadly
• This manifests into cracking and bulging of concrete.
• The crack width can range from 0.1mm to as much as 10mm.

12. Alkali Silica Reaction (ASR)
Alkalis
+
Reactive
Silica
+
Moisture
ASR
Gel
which
expands
Concrete
expansion
and
cracking
What is ASR?

13. Alkali Silica Reaction (ASR)
Sodium hydroxide and potassium oxide in cement, they form their hydroxyl ion
and then reacts with the siliceous materials forming alkali silicate gel and attract
water, by absorption or by osmosis and tend to increase the volume.

14. Concrete failure due to ASR
https://www.google.co.in/search?rlz=1C1CHBF_enIN765IN765&biw=1366&bih=613&tbm=isch&sa=1&q=alkali+silica+reaction+in+concrete&oq=A
alkali+silia+&gs_l=psy-ab.1.0.0i13k1l4.70654.76401.0.78086.14.14.0.0.0.0.165.1906.0j13.13.0....0...1.1.64.psy-
ab..1.13.1899...0j0i67k1j0i10i30k1j0i30k1j0i10i24k1j0i13i5i30k1j0i13i30k1.0.DtDDvhcsPOI#imgrc=fPHCtwo7_iVLWM:

15.  Prevention of moisture is most important, because this reaction takes place in presence of
moisture.
 Use of ground granulated blast furnace slag or fly ash, they actually reduce the alkali aggregate
reactivity.
 Do not use aggregate potentially prone to ASR. Geological origin of the aggregates looked by
geological test looking into microscope and identifying the
 mineralogical composition.

16. SULPHATE ATTACK
• Sulphate attack denotes an increase in the volume of cement paste in concrete
or mortar due to chemical action between the products of hydration of cement
and solution containing sulphate.
• As sulphate dries, new compounds are formed, often called Ettringite.
(calcium sulphoaluminate hydrate)
• These new crystals occupy empty space, and as they continue to form, they
cause the paste to crack, further damaging the concrete

17. MECHANISM OF SULPHATE ATTACK
NA2SO4+CA(OH)2 +2H2O = CASO4.2H2O +2NAOH

18.  Sulfate attack can be 'external' or 'internal'.
 External: due to penetration of sulphates into the concrete from outside
For example : high-sulphate soils and ground waters, or atmospheric or
industrial water pollution.
 Internal: due to a soluble source being incorporated into the concrete at the
time of mixing, gypsum in the aggregate.
For example:
 Portland cement might be over-sulphated.
 presence of natural gypsum in the aggregate.
 Admixtures also can contain small amounts of sulphates.

19. SULPHATE ATTACK

20. • Low water cement ratio improves sulphate resistance . Due to reduction in the water cement
ratio, sulphate will not be able to penetrate into to the concrete.
• Low C3A cement, blended cement improves sulphate resistance. Cement with fly ash
improves sulphate resistance because, it will reduce down the C 3 A content because cement
will be some percent and remaining percent is fly ash

21. STEEL CORROSION
• The corrosion of steel reinforcement in concrete is complex, but basically it is an
electrochemical reaction.
• Concentration cells are formed when two dissimilar metals are embedded in
concrete, such as steel rebar and aluminium conduit pipes,
• Concentration cells may be formed due to differences in concentration of dissolved
ions near steel, such as alkalis, chlorides, and oxygen.

22. • The differences in electrochemical potential can arise from differences in the
environment of the concrete. Electrochemical cells form also due to a variation in
salt concentration in the pore water or due to a non-uniform access to oxygen.
• Thus, one of the two metals (or some parts of the metal when only one metal is
present) becomes anodic and the other cathodic.

23. LITERATURE REVIEW
Author Published
in year
Title of study Outcome of study
M.M.H.A.
Tholaia, A.K.
Azad, S.
Ahmad, M.H.
Baluch
2014 A comparative study of
corrosion resistance of
different coatings for mortar
embedded steel plates
Epoxy-coating distinctly shows a much superior performance
against the steel corrosion compared with red-oxide and zinc
primer coatings
K.A. Chandler,
D.A. Bayliss
1985 Corrosion Protection of
Steel Structures with Zinc
coating of steel
The stability of zinc is dependent on the pH of the
surrounding solution where the zinc coating is exposed. linear
relationship between the metal thickness and the duration of
its effective service life for galvanized steel exposed to an
industrial atmosphere

24. Author Published
in year
Title of study Outcome of study
S.A. Asipita, M.
Ismail, M.Z.A.
Majid, Z.A.
Majid, C.
Abdullah, J.
Mirza,
2014 Green Bambusa Arundinacea
leaves extract as a sustainable
corrosion inhibitor in steel
reinforced concrete
Green inhibitor , Bambusa Arundinacea leaves extract exhibits
better resistance to steel corrosion compared with calcium
nitrite and ethanolamine.
T.A. Soylev, T.
Ozturan
2014 Durability, physical and
mechanical properties of
fiber- reinforced concrete at
low-volume fraction
Fibrous composites are usually made of continuous fibres
(carbon and stable glass) as reinforcement and polymers (epoxy
and polyester) as the matrix eliminate the corrosion problem
W.T.Kuo,H.Y
Wang and C.Y
Shu
2014 Engineering properties of
cementless concrete produced
from GGBFS and recycled
desulfurization slag,
Construction
The incorporation of more than 30% of low reactivity ground
granulated blast furnace slag led to a notable enhancement of
the mortars efficiency against sodium and magnesium sulphate
attacks.

25. IS 456:2000 RECOMMENDATIONS
Exposure condition :The general environment to which the concrete will be exposed during
its working life is classified into five levels of severity.

26. FREEZE AND THAW
Where freezing & thawing actions exist, using grade of concrete lower than M 50, enhanced
durability can be obtained by the use of suitable air entraining admixtures.
Exposure to sulphate attack
Table 4 of IS 456(2000) shows recommendations for the type of cement, maximum free
water/cement ratio and minimum cement content, which are required at different sulphate
concentration in near-neutral ground water having pH of 6 to 9

28. CONCRETE MIX PROPORTION
The free water-cement ration is an important factor in governing the durability of concrete and
should always be the lowest value. Appropriate values for minimum cement content and the
maximum free water-cement ratio are given below.

29. ALKALI-AGGREGATE REACTION
• Use of non-reactive aggregate from alternate sources.
• Use of low alkali ordinary Portland cement having total alkali content not more than 0.6
percent(as Na20 equivalent).
• Measures to reduce the degree of saturation of the concrete during service such as use of
impermeable membranes.

30. CONCLUSION
• This study has covered the body of literature that pertains to recent research activities regarding to
durability. The various recommendations to make concrete more durable are:
• Exercising adequate care at every stage of planning, analysis, design and construction for the expected
exposure conditions.
• The performance of structures should be monitored regularly from the stage of commencing.
• Adding optimal type and amount of Pozzolanic materials is a cost-effective approach to improve the
durability performance to some extent.

31. • The study of natural green inhibitor for steel corrosion also opens a promising research direction in
the near future.
• Good quality concrete mix with the lowest water cement ratio compatible with practical placement
and finishing techniques should be used.
• Concrete should be properly placed, consolidated and cured.
• Application of flexible surface coatings to avoid concrete surfaces, which can effectively control the
ingress of chlorides, sulphates, carbon dioxide, oxygen and moisture, can be considered as an
effective corrosion control measure.
CONCLUSION

32. REFERENCES
• Asipita, S.A.,Ismail,M.A., Majid, M.Z.A.,Mirza,J.A. (2014), Green Bambusa Arundinacea leaves
extract as a sustainable corrosion inhibitor in steel reinforced concrete, J. Clean. Prod. 67 139–146
• Dai Q.L., and Kyi,H.L, (2014), Transmission X-ray microscope nanoscale characterization and 3D
micromechanical modelling of internal frost damage in cement paste, J. Nanomech. Micromech. 4
(A4013005-1-A4013005-10).
• Kuo,W.T., Wang,H.Y. and Shu,C.Y. (2014),Engineering properties of cementless concrete produced
from GGBFS and recycled desulfurization slag, Construction. Building Material 63 189–196
• Soylev,T.A. and Ozturan,T. (2014), Durability, physical and mechanical properties of fiber- reinforced
concrete at low-volume fraction, Construction Building Material 73 67–75
• Tholaia, M. M. H., Azad, A. K., Ahmad, S., & Baluch, M. H. (2014), A comparative study of
corrosion resistance of different coatings for mortar-embedded steel plates. Construction and Building
Materials, 56, 74–80.

33. THANK YOU