This International Conference on Emerging Smart Materials in Applied Chemistry (ESMAC-2020),10-12th August,2020 webinar was organised by Dep't of Chemistry,Kalinga Institute of Industrial Technology,Bhubaneswar

1. - Prof.Mainak Ghosal
Jt.Secretary,

2.  What is Concrete Durability ?
 Some Case Studies
 Consequences of Inadequate Durability
 Factors Affecting Durability of Concrete
 Role of nano-TiO2 in Concrete Durability
 My Research
 Results & Discussions
 Conclusion

3. Definition
 A durable concrete is one that performs satisfactorily in the working environment during its
anticipated exposure conditions during service(IS:456-2000)
 Durability of concrete is its ability to resist weathering action, chemical attack, abrasion or
any other process of deterioration(American Concrete Institute-ACI)
 When exposed to environment durable concrete is likely to retain its original form, quality
& serviceability during its lifetime.
 Durable concrete envisages limits for max. water-cement ratio, min. cement content, cover
thickness, type of cement used & presence of amounts of Cl-1/SO4
-2 in concrete(IS-SP-28)
 As low permeability as possible under situation(IS-SP-23)

4. Failure is the pillar of success – Do we need such failure to succeed ?

5. Courtsey:Sandip Das Gupta, Zonal Technical Head(East),JSW Cement

6.  Loss of strength of concrete
 Concrete liable to be easily affected by deterrents
 Corrosion of re-bars
 Loss of serviceability
 Unpleasant appearance
 Danger to persons & property
 Expensive repair costs
 Poor perception of concrete as a material
 Poor perception of agencies involved
 Reduction of service life
 External Risks – weathering, attacks by nature/chemicals/bacteria etc.

8.  Cement Content & type leading to Lime Leaching
 Water Quality & Quantity
 Permeability
 Temperature(Atmospheric & Core)
 Carbonation
 Alkali-Aggregate Reaction
 Sulfate & Chloride Attack
 Organic Acids
 Aggregate Quality
 Concrete Compaction
 Curing Period
 Moisture
 Abrasion
 Wetting & Drying Cycles
 Freezing & Thawing

9. OPC Water C-S-H
gel
Ca(OH)2

10. Cement Hydration
Courtesy: Price,
W.H., ACI J.,
22(6), 417–432,
1951

11. Microstructure of Concrete consists of
• Aggregates(CA,FA)
• Hydrated cement paste
• Entrapped air voids
Factors affecting
Microstructure of
Concrete
• Hydrated cement paste(C-S-H)
• Ettringite
• Mono-sulfate
• Gel porosity & Capillary pores
• Entrained/Entrapped air voids
• Transition zone(TZ)
https://www.intechop
en.com/books/high-
performance-
concrete-technology-
and-
applications/microstru
cture-of-concrete

12. Visible Cracks in Hydrated Cement Paste & aggregates due to
volume change (to understand Cracks we need to look at
Microstructure)
-----------------------------------------------------------------------------------------------
 Alkali-Silica Reaction : Reaction product forms at TZ & expands
Frost Action : Water freezes in capillary pores & expands
Sulfate & Chloride Attack : Reaction products form in Hydrated
Cement Paste(mainly OPC with greater clinker content & unreacted
lime) & expand
Porosity & Permeability : Leads to Corrosion in Rebars

15. Signs of sulfate attack
 Extensive cracking & expansion(damage starts at edges & corners)
 Ettringite crystal formation & deposition in cracks/internal voids
 Whitish appearances on surface
Where ?
Inland/Coastal polluted areas mainly
Chemical Reactions:
Ettringite formation
Expansion Mechanism: Crystallization Pressure theory
Swelling theory
Ettringite Formation

18. Signs of chloride attack
 40% contribution among all failures
 Corrodes reinforcement
Where ?
Coastal areas mainly
Chemical Reactions:
Calcium Chloroaluminates(Friedel’s Salt) formation
Expansion Mechanism: Crystallization Pressure theory
Swelling theory
Calcium Chloroaluminates Formation

19. Soluble CaCl2

21. Due to its Self-Healing properties
M. Pelaez et al., A review on the
visible light active titanium dioxide
photocatalysts for environmental
applications*, Applied Catalysis B,
Environmental (2010),
doi:10.1016/j.apcatb.2012.05.036

22. Increase in surface area atom efficiency

23. Titanium Dioxide
• Excellent Self-Cleansing Properties due to oxidation of organic
materials
• Improves the Compressive strength of Cement & Concrete
under adverse conditions
c
Conventional
Glass
Self-Cleaning
Glass
Boostani H., Modirrousta S. Review of nanocoatings for building application. Procedia Eng. 2016;
145:1541-1548. doi:10.1016/j.proeng.2016.04.194

24. Application
Coatings Fabrications

25. Coatings examples…
Broekhuizen, F.; Broekhuizen, P. Nano-Products in the European Construction Industry—State of the Art 2009; IVAM: Amsterdam, The
Netherlands, 2009.

26. Fabrications examples.
Broekhuizen, F.; Broekhuizen, P. Nano-Products in the European Construction
Industry—State of the Art 2009; IVAM: Amsterdam, The Netherlands, 2009.

27. Painting Restorations…
A. M. Waked, WIT Transactions
on The Built Environment, Vol
118, © 2011 WIT Press
doi:10.2495/STR110481,
www.witpress.com, ISSN 1743-
3509 (on-line)

28. World usage of n-TiO2

29. Cement
n – TiO2
Ghosal et al “A Comparative Assessment of Nano-SiO2 & Nano-TiO2 Insertion in Concrete”, European Journal of Advances in Engineering and Technology, (2015), pp. 44-48.

30. Item Description
Supplier Kerala Minerals &
Metals Ltd.
% Purity 97%
Rutile Content 98%
pH 7
Average particle
size (TEM)
30-40 nm
Moisture % 1.75-2
Bulk Density 0.31gm/cc
Water Solubility In-soluble

32. S
T
R
E
N
G
T
H,
(N/mm2) 7 Days 28 Days 90 Days 180 Days 365 Days
20
25
30
35
40
45
Ref.
Sample
1% n-TiO2
Sample
2.5% n-TiO2
Sample
Strength at various Ages of Nano TiO2 added OPC Mortar

33. Ref. Sample 1% n-TiO2 Sample

34. 0
10
20
30
40
50
60
70
80
90 Day 180 Day 365 Day
CompressiveStrength,N/mm2
Strength at various Ages of M40 Concrete & TiO2 added Nanoconcrete at
MgCl2 Exposure
M 40 Concrete
1% TiO2 Nanoconcrete

35. 0
10
20
30
40
50
60
70
80
90 Day 180 Day 365 Day
CompressiveStrength,N/mm2
Strength at various Ages of M40 Concrete & TiO2 added Nanoconcrete at MgSO4
Exposure
M 40 Concrete
1% TiO2 Nanoconcrete

36. • Though Pozzolona Cement(Ash based) is good for
Resisting Chloride Attacks & Slag Cement is for
Resisting Sulfate Attacks.
• nano-TiO2 (@ 1% b.w.c optimization) is good for
Resisting the Both.

37. Thank
You!