Pervious concrete is a type of concrete with high porosity that allows water to pass through, reducing runoff. It was first used in Europe in the 1800s and became popular again in the 1920s for homes in Scotland and England. The mix design includes aggregates, cementitious materials, and water, with void contents between 15-30% and water-cement ratios of 0.28-0.40. Pervious concrete is used for flatwork applications and subgrade installations, and provides environmental, safety, and economic benefits like reduced runoff and maintenance costs, though it also has disadvantages like needing extended curing times.
4. What Is Pervious Concrete
• Pervious concrete is a special type of
concrete with a high porosity used
for concrete flatwork applications
that allows water from precipitation
and other resources to pass through
it, thereby reducing the runoff from a
site and recharging ground water
levels.
4
5. History Of Pervious Concrete
Pervious concrete was first used
in the 1800s in Europe. It became
popular again in the 1920s for two
story homes in Scotland and
England. It became increasingly
viable in Europe after the Second
World War due to the Scarcity of
cement. It did not become as
popular in the US until the 1970s
5
6. Mix Design
• Aggregates
• Cementious Materials
• Water
• Admixtures
Ranges Of Materials
Design Void Content: 15% to 30%
Water to Cement Ratio: 0.28 to 0.40
Binder to Aggregate Ratio: below 0.25
6
7. A mix design with little water can create a very
weak binder. This will create a very dry mix that is
susceptible to spalling and crumbling.
Correct amount of water
A mix design with too much water can collapse
the void space, making an almost impenetrable
concrete surface
7
8. Aggregates
• Pervious concrete has little or no fine aggregates in the
mixture. Aggregate size is typically between 3/8 to1/2
inch maximum
8
9. Cementious materials
• Typically type-I cement is used for the production of pervious concrete.
• Supplementary cementious materials such as fly ash or slag can be used in
exchange up to about 25% (fly ash) and up to about 50%(slag) of cement.
9
10. Water
• Water meeting standard requirements for conventional
concrete can be used for the production of pervious concrete
10
11. Admixtures
• Air entraining admixtures may be used to improve the
freeze/thaw durability of the paste/mortar.
11
13. Sub-grade Layer
• This is the undisturbed soil underneath the sub-base layer. Sub-grade layer
infiltration rate determines how much water can be absorbed within a given time.
This directly affects the size of the sub-base layer. If the infiltration rate is too low,
larger sub-base or drainage should be considered. If the sub-grade is too fine, it may
be necessary to place geo-textile in between the sub-base and sub-grade to
minimize the migration of fine soil particles into the sub-base. Omitting this could
lead to clogging and reduced retention capacity
13
15. Drainage
• A drainage system is not always necessary but may be needed
when the infiltration rate of the sub-grade layer is low and water
contained in the sub-base cannot be absorbed by soil quickly
enough.
15
21. 3. Mechanical / manual vibrating screeds
Commonly used technique, which is simple
and fast.
21
22. Keep in mind….
• Maintenance such as vacuuming or sweeping may be required
in certain areas to preserve pervious properties
• Pervious concrete is only as good as its design and installation.
vacuum for sweeping
pervious pavements
22
25. Environmental benefits
• Reduces storm water runoff
• Water management practices
• Mitigation surface pollutants
pervious water
allows recharging
the ground level
25
26. Safety
• Reduce tire sound
• Prevents glare
Economics
• Low maintenance cost
• More life span
26
27. DISADVANTAGES
• Extended curing time
• Limited use in heavy vehicle traffic areas
• Frequent maintenance is required
• Compressive strength is low
• Special care in expansive soils & high ground water
conditions
27
28. CONCLUSION
• The pervious concrete helps the water to
infiltrate
• Cities with pervious pavements would be safer
for traffic, be cleaner and less pollution
28
