This document discusses abrasion, erosion, and cavitation in concrete structures. It provides information on: 1) Abrasion is the wearing away of concrete surfaces through repeated rubbing, rolling, or sliding. Factors like water-cement ratio, aggregate grading, air content, curing, and finishing procedures affect abrasion resistance. 2) Erosion occurs when flowing water carrying solid particles damages concrete surfaces. Factors like particle size, velocity, and quality of concrete determine the degree of erosion. Erosion involves abrasive and cavitation actions. 3) Cavitation is the formation and collapse of air bubbles in water causing intense local stresses that damage concrete. Locations prone to cavitation

1. Abrasion, Erosion & Cavitation
Birla Vishvakarma Mahavidyalaya Engineering College
(An Autonomous Institution)
Affiliated with Gujarat Technological University
GUIDED BY:
Prof. DEEPA SINHA
STRUCTURE ENGINEERING DEPARTMENT
PREPARAID BY:
CHETAN GONDALIYA
(16CE006)
SUBJECT: Repair and Rehabilitation of Structures (SE453)
TOPIC:
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2. • Wearing away of the surface of a material
• Wearing of surface caused by...
- repeated rubbing, rolling, sliding, or frictional (attrition)
processes
- repeated action of lightly loaded rubber tires or foot traffic,
in the form of dusting, loss of surface texture, and polishing
• Manifested by
- localized crushing, scratching or attrition (when abrasive
medium is present), in case of heavily loaded steel wheels
Abrasion
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3. Fig: Wear of concrete surface by abrasion
 Abrasion damage
Fig: Abrasion damage due to concrete baffle
blocks and floor area of dam sluiceway
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4. 1. Factors Impacting Concrete Strength
• Factors that directly affect concrete strength would influence concrete abrasion
resistance as well. For example, low water to cement ratio, low slump value, well-
graded aggregate, and air content.
Fig: Water to Cement Ratio
 Factors Affecting Abrasion Resistance of Concrete Surface
1.1 W/C Ratio
• Low to moderately w/c ratio ensure the decrease of free
water in concrete. This improves concrete compactness
and reduces permeability which consequently improves
concrete strength and hence abrasion resistance.
• W/C ratio can be decreased by using water-reducing
admixtures, mixture proportions to reduce bleeding, the
timing of finishing operations that avoid the addition of
water during troweling, and vacuum dewatering.
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5. 1.2 Well-Graded Aggregate
• The use of well-graded fine and coarse
aggregate can optimize workability and
minimize water content. This would improve
concrete strength considerably
Fig: Grades of Aggregate
1.3 Air Content
• Not only does air content leads to the reduction of concrete strength but also contributes to concrete
surface delamination and blistering especially when finishing works are times improperly.
• So, air content should not be considered for concrete when abrasion resistance is required unless
special considerations are followed. For instance, hard troweling of the surface should not be done on
concrete having a total air content greater than 3 percent.
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6. 2. Proper Curing Procedure
• Proper curing procedure is a major element in the
construction of floor surfaces with satisfactory
abrasion resistance. This is because it contributes to
increased concrete strength and toughness. These
characteristics are the most important factors for
ensuring resistance to surface abrasion. Keeping
concrete continuously wet is a desired curing regime
for the majority of concrete floors, as per American
concrete institute.
Fig: Curing Concrete Slab
3. Use of Supplementary Cementitious Materials
• It is demonstrated that, if properly and adequately cured, polymer concrete, polymer-
impregnated concrete, epoxy concrete, calcium aluminate cement, and calcium
sulphoaluminate cement provide exceptional abrasion resistance.
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7. 4. Two-course Floors
• The use of two-course floors using high strength topping in excess of 40MPa would
provide excellent abrasion resistance. Nonetheless, this type of floor is more expensive
compared with other conventional floors. It should be known that the two-course floor
is used when abrasion and impact resistance is needed.
5. Special Concrete Aggregates
• Type of aggregate is among factors that affect abrasion resistance of concrete. The use
of hard and tough aggregates can increase the life span of floors, such as warehouse
floors, that subjected to severe abrasion by steel or hard rubber-wheeled traffic.
• Abrasion-resistant aggregates are commonly applied as dry shakes or in high-strength,
bonded toppings. Dry shakes are a mixture of aggregates with cement which is applied
dry to the concrete surface during finishing operations.
• When abrasion resistance is a fundamental concern, then high-quality quartz, traprock,
emery aggregate is recommended to be used because such aggregate improves the
strength of concrete surface. The abrasion resistance of concrete surface can be further
increased by using metallic aggregates with cement.
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8. 6. Proper Finishing Procedures
• The use of proper finishing time and procedure is another factor that influences abrasion
resistance of concrete. Floating and troweling operations begin when the surface sheen
of concrete is lost.
• So, finishing works should be delayed until concrete surface reach this point. The delay
period is based on temperature, humidity, air movement, and supplementary
cementitious materials used.
• Finally, standing water should never be worked into concrete surfaces because it reduces
the compressive strength of the surface paste.
7. Vacuum Dewatering
• Vacuum dewatering reduces w/cm ratio which leads to increase concrete strength and
abrasion resistance, but one should be aware that the quality of the finished surface is
still highly dependent on the timing of finishing.
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Compressive strength Water cement ratio Hardness of aggregate

10.  Current test methods
• Numerous ASTM test methods
•Test method for abrasion resistance of concrete by sand blasting (ASTM C 418)
•Test method for obtaining and testing drilled cores and sawed beams of concrete (ASTM C 944)
•Test method for abrasion resistance of horizontal concrete surfaces (ASTM C 779)
•Test method for abrasion resistance of concrete - Underwater method (ASTM C 1138)
“Chosen based on how closely the expected service conditions are matched by the test”
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11. • Use higher compressive strength
• Use lower w-c ratio
• Use harder aggregates
• Use well-graded sand instead of fine sand
• Use larger aggregates than smaller aggregates
• Ensure water curing than air-curing
• Avoid formation of laitance
-weak layer of concrete on surface due to bleeding/segregation of fresh concrete
(dusting)
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 How to ensure good abrasion resistance?
fig: Laitance on concrete surface

12. • Erosion is one form of wearing of concrete that is
observed in contact with flowing water.
• The water body that results erosion may carry solid
particles which leads to serious erosion to concrete.
• The concrete quality, especially in surface zone is
very important to resist erosion of concrete. We will
provide factors and ways to control erosion in the
very next post.
• Like, abrasion the resistance against erosion is also
related to the strength of concrete but mix
composition of concrete is also vital.
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Erosion

13. • Erosion is a mechanical damage of concrete which is
frequently associated with corrosion.
• Marine concrete is the ideal example of such
damage.
• With this corrosion effects, erosion is happened
when mechanical damage to concrete is occurred by
the waves of water with gravel and sand carried by
them.
• Sometimes crystallized salt takes the part of
impacting from carried particles.
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14. • Open channels
• Closed conduits
• Spillways
• Gutters
• Aprons
• Stilling Basins
• sluice ways
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 Erosion occurs primarily in

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• Quantity of the transported particles
• Shape of these particles
• Size of these particles
• Hardness of these particles
• Velocity of particle movement
• Formation of eddies
• At last quality of concrete
 factors that determine the degree of erosion

16. • Abrasive action
- Impact of debris present in water on concrete surface
• Cavitation action
- Formation and collapse of air cavities causing intense, local stresses
• Chemical action
- Dissolution of hydrated Portland cement compounds
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 Erosion is physical distress of concrete due to…

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 Erosion – Abrasive action

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 Erosion – abrasive + cavitation actions

19. • Cavities will form in running water whenever the
pressure in the water drops below the vapor pressure.
• When these bubbles collapse under higher pressure,
they do so with great impact.
• As the bubbles collapse, the air space gets occupied by
high- velocity water, extremely high pressure is
generated on a small area, momentarily.
• Cavitation damage is more pronounced when large
number of minute bubbles coalesce to form larger
bubbles, which then collapse.
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 Why does cavitation lead to damage in concrete?
Cavitation

20. • Cavitation damage in concrete Occurs primarily
in locations, where rapid development and
dissipation of air bubbles occurs,
- Stilling basins
- Open channels, spillways
- Closed conduits (tunnels, storm drains, etc.)
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 Cavitation damage in concrete

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 Spillway damage at Oroville dam, Oregon, USA (in 2019)

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 Ways to protect against cavitation
• High-strength concrete containing small aggregates.
• Smooth concrete surfaces with minimal irregularities.
• Good aggregate-paste bond Aggregate hardness is not as important for
cavitation resistance, unlike for erosion resistance.
• Sudden increase in velocity of water should be minimized.
• Purposeful aeration of concrete
-The air bubbles act to cushion the impact of the imploding bubbles in the
cavitation process.
-This is achieved by designing for aeration in the structures.

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 Conclusion
• Properties of aggregates and the strength of concrete influences abrasion,
erosion and cavitation resistance.
• Shape of the structure and surface irregularities influence a lot on erosion
and cavitation

24. Thank
you
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