1. Durability of Concrete-A Literature Review
(Chloride Attack)
K Prakash Kumar Singh, Prof. Dr. Prakash Nanthagopalan
Department of Civil Engineering, Indian Institute of Technology Bombay
Abstract
Durability of concrete represents its ability to resist weathering action,
chemical attack, abrasion or any other process of deterioration. The
consequences of factors which influence the durability of concrete are
dangerous and costly. Different types of standard tests are performed to
check the impact of these factors. The mechanisms of fluid and ions
flow through the concrete are capillary suction, diffusion, migration
and permeation. The parameters which are remarkably used to study
the chloride penetration are surface chloride, apparent diffusion
coefficient, chloride threshold and chloride penetration. The chloride
penetration causes the pitting corrosion. The corrosion process of steel
is an electrochemical reaction The corrosion model defines the
different stages of corrosion, i.e. initiation, propagation and
acceleration. The cracking-corrosion-cracking model represents the
consequences of the factors that influence the durability of concrete.
Objective
To study the factors influencing the durability of concrete and its
consequences. To study the Chloride Penetration in details which
includes different types of mechanisms of fluids and ions flow through
the concrete, the parameters and the standard tests. The corrosion of
reinforcements in which types of corrosion, corrosion model, cracking-
corrosion-cracking model and electrochemical process are studied.
Factors Influencing Durability
Durability
Standard Tests for
• V. M. Malhotra; “Durability of Concrete”, Proceedings 2nd
International Conference Montreal, Canada 1991.
• Luca B.,B. Elsener, P. Pedeferri, R. Polder; “Corrosion of
Steel in Concrete Prevention, Diagnosis, Repair”.
• K.D. Stanish, R.D. Hooton and M.D.A. Thomas; “Testing the
Chloride Penetration Resistance of Concrete:A Literature
Review”.
Corrosion
Cracking-Corrosion-Cracking Model
References
Alkali Aggregate Reaction
Test Methods for evaluating aggregate reactivity
• ASTM C 295; IS:2386 (PART-VIII)-1963 : - Standard guide for
petrographic examination of aggregates for concrete
• ASTM C 227; IS:2386 (PART-VII)-1963 : - Test method for
potential Alkali Reactivity of cement-aggregate combinations
(Mortar-Bar Method)
• ASTM C 289 : - Test method for potential ASR of aggregates
(Chemical Method)
• AASHTO T 303; ASTM C 1260 : - Test method for potential Alkali
Reactivity of Aggregates (Mortar-Bar Method)
• ASTM C 1293: - Test method for concrete aggregates by
determination of length change of concrete due to Alkali-Silica-
Reaction (Concrete Prism Test). It is long term test (1 year).
Test Methods for evaluating preventive measures
• ASTM C 441 : - Test Method for Effectiveness of Mineral
Admixtures or Ground Blast-Furnace Slag in preventive excessive
expansion of concrete due to the ASR
• ASTM C 1567-13: - Test method for determining the potential ASR
of combinations of cementitious material and aggregate (Accelerated
Mortar-Bar Method).
Freeze and Thaw
• ASTM C 666/C666M-15 : - Test Method for resistance of concrete to
rapid freezing and thawing
• ASTM C672/C672M-12 : - Test method for scaling resistance of
concrete surfaces exposed to Deicing Chemicals
Acid Attack
• ASTM C267-01(2012) : - Test method for chemical resistance of
mortars, grouts, and Monolithic Surfacing and Polymer Concrete
Abrasion Resistance
• ASTM C418-12 : - Test method for abrasion resistance of concrete by
sandblasting
• ASTM C944/C944M-12 : - Test method for abrasion resistance of
concrete or Mortar Surfaces by the rotating cutter method
• ASTM C779/C779M-12 : - Test method for abrasion resistance of
Horizontal Concrete Surfaces
• ASTM C1138M-12 : - Test method for abrasion resistance of
concrete (Underwater Method)
Cyclic Wetting and Drying
•ASTM D559/D559M-15; IS:4332 (PART-IV)-1968 : - Test methods
for wetting and drying compacted soil-cement mixtures
Chloride Attack
Parameters
• Surface Chloride, : - Chloride Concentration on the surface of the
concrete. Depends on composition of concrete, position of structure,
orientation of surface, etc. Highest in splash zone of marine structure
due to wet-dry cycle.
• Apparent Diffusion Coefficient, ∶ Values in between
10 10 m^2/sec. Depends on pore structure, w/c,
compaction, curing, exposure conditions, etc.
• Threshold Chloride, : - Minimum amount of chloride required for
corrosion of reinforcements (pitting corrosion). Available oxygen and
moisture content have remarkable influence on it.
• Chloride Penetration: - Chloride Penetration Profile- Higher
concentration at surface and gradually decreases as we go inside the
concrete.
Mechanisms
• Capillary Suction: - Solution adsorbed rapidly by the under-
pressure in the pores
• Diffusion : - Ions movements due to concentration gradient.
• Stationary Diffusion- Constant mass transfer- Fick’s
1st law is used. Flux = ∗ . is a material
property.
• Non-Stationary Diffusion- Rate of mass transfer
varies with time. Fick’s 2nd Law is used. ,
2 ∗ 1 .
• Migration: - Ions movement due to electrical potential gradient.
• Permeation: - Ions movement due to pressure gradient.
Standard Tests [Test period]
• Salt Ponding Test (AASHTO T 259) [90days]
• Rapid Chloride Penetration Test (AASHTO T277; ASTM
1202-12) [6 hours]
• Bulk Diffusion Test (NT BUILD 443; ASTM C1556-16)[40-120
days after curing and conditioning]
• Rapid Migration Test (NT BUILD 492) [8 hours]
• Electrical Migration Test (NT BUILD 355)[Depends on V & I]
• Resistivity Technique (ASTM C1760-12) [30 minutes]
• Pressure Penetration Technique (BS EN12390-8) [Depends on
Pressure and Concrete]
• Sorptivity Test (BS 1881 (PART 122);ASTM C1585-13) [1
week including conditioning in Lab; 30 mins. In Field]
Steel
Concrete
e-e-
Fe2+,H+,
Cl-
OH-
O2
OH-
Anode
CathodeCathode
Passive Film
Pitting Corrosion
I II III I- Initiation of Corrosion
II- Propagation of Corrosion
III-Acceleration of Corrosion
Corrosion Model
Time
DegreeofCorrosion
Concrete Contains
Microcracks
Highly Permeable
Concrete
Corrosion of Embedded
Steel
Cracking Growth
1.Humidity and Temperature Gradients
2.Impact of floating objects
3.Chemical Attacks, Leaching of Cement
Paste
4.Freeze-Thaw,Overload and other factors
increasing the permeability of concrete
Electrochemical Mechanism of Corrosion of Steel in Concrete
Anodic Process
Cathodic Process
Transport of Current
within the metal
Transport of Current
within the concrete
Ia=Icon=Ic=Im
The Concrete
System
Aggressiveness
of the
environment
Materials
• Binder Type
• Binder
Content
• Aggregates
• Admixture
• Mixture
Design
Process
• Mixing
• Transporting
• Compaction
• Curing
• Temperature
• Workmanship
Physical
• Abrasion
• Erosion
• Cavitation
• Freeze-
Thaw
Chemical
• Dissolution
• Leaching
• Expansion
• Alteration
Consequences
Loss of strength
Concrete Liable to be easily affected by deterrents
Corrosion of rebar
Loss of Serviceability
Unpleasant appearance
Danger to Persons and Properties
Poor Perception of Concrete as a Material
Poor Perception of Agencies involved
Reduction of Service Life
External aggressive agents attack
Ingress of Moisture/Air facilitating Corrosion of Steel
Cracking of Cover