Also known as No fines, gap graded
or porous 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 sources to pass directly through, thereby reducing the runoff from a
site and allowing groundwater recharge
• The high porosity is attained by a highly interconnected void content.
Recognized as the best management practice
by US Environment Protection agency (EPA)
• It is a mixture of Cement, Corse aggregate and with or without sand (Fine
aggregate) and has enough cementitious paste to coat the coarse
aggregate while preserving the interconnectivity of the voids.
• This concrete is being used as paving material to solve or reduce the
storm water runoff to the drainage system and minimize water logging
• It is an important application for sustainable construction and is one of
many low impact development techniques used by builders to
protect water quality.
Difference between Pervious and
Pervious concrete pavements
• A mixture of Cement, Corse aggregate and with or without
• Controlled amounts of water and cementitious material are
used to create a paste that forms a thick coating around
aggregate particles without flowing off during mixing and
• Typical pervious concrete pavements has a 15-20% void
structures. It is consequently lightweight, with density of
1600 to 1900 kg/m³
• It depends on the properties and proportions of the materials used,
and on the compaction procedures used in placement. In place
densities on the order of 1600 kg/m³ to 2000 kg/m³ are common,
which is in the upper range of lightweight concretes.
• It depends on the materials and placing operations. Typical flow
rates for water through pervious concrete are 120 L /m^2/min, or
• 0.2 cm/s to 320 L /m^2/min, or 0.54 cm/s.
• Pervious concrete mixtures can develop compressive strengths in
the range 3.5 MPa to 28 MPa, which is suitable for a wide range of
applications. Typical values are about 17 MPa.
• It generally ranges between about 1 MPa and 3.8 MPa
• factors influence the flexural strength are
• degree of compaction,
• the aggregate: cement (A/C) ratio.
• Drying shrinkage of pervious concrete develops sooner, but is much less than
conventional concrete. (0.002, roughly half to that of conventional concrete mixtures)
• Roughly 50% to 80% of shrinkage occurs in the first 10 days, compared to 20% to 30% in
the same period for conventional concrete.
• Because of this lower shrinkage and the surface texture, many pervious concretes are
made without control joints and allowed to crack randomly.
Freeze-thaw resistance: It depends on the saturation level of the voids in the concrete
at the time of freezing.
deterioration of concrete exposed to freeze-thaw
joint deterioration due to cracking
Snow-covered pervious concrete
clears quicker, possibly because its
voids allow the snow to thaw more
quickly that it would on
The open structure of pervious concrete makes it more
susceptible to acid and sulphate attack over a larger area than
in conventional concrete.
Because of the rougher surface texture and open structure of
pervious concrete, abrasion and raveling of aggregate
particles can be a problem.
This is one reason why applications such as highways
generally are not suitable for pervious concretes.
Mix design and placement
different surface textures can
be obtained through the use
of different maximum sizes
Samples of pervious concrete with different water
contents, formed into a ball: too little water, proper
amount of water, and too much water.
Typical Ranges of Materials
Proportions in Pervious Concrete
270 - 415
Narrowly graded aggregate
1190 - 1480
0.25 - 0.34 (with chemical admixtures)
0.34 - 0.40 (without chemical admixtures)
Cementitious materials/Aggregate ratio
1 : 0.21 – 0.25
Fine aggregate : coarse aggregate ratio
0 to 1 : 1
Polypropylene fibres (optional when no
fine aggregate is present)
0.1% by volume or 0.9 kg/m³
• A pervious pavement mixture should be discharge completely
within one hour after initial mixing.
• The use of retarding chemicals admixtures or hydrationstabilizing admixtures may extend discharge time to 1 ½ hours
• Cement may be replaced by about 10-30% of fly ash, 20-50%
blast furnace slag and 5% of silica fume.
• Addition of the fine aggregate will decrease the porosity and
Placement and Consolidation
• Sub-base preparation and forms should be double checked,
prior to placement.
• Placement should be continuous and spreading should be
• Mechanical vibrating, laser screeds and manual screeds are
commonly used, although manual screeds can cause tears in
the surface if the mixtures is too stiff.
• Consolidation is generally accomplished by rolling over the
concrete with a steel roller, which compacts the concrete to
the height of the forms.
• Because of rapid hardening and high evaporation rates, delays
in consolidation can cause problems.
Placement and strike off using vibrating screed
As pervious concrete pavements do not bleed, they can have a high propensity for
plastic shrinkage cracking.
In fact, “curing” for pervious slabs and pavements begins before the concrete is
placed – the sub grade must be moistened to prevent it from absorbing moisture
from the concrete.
After placement, fog misting followed by plastic sheeting is the recommended
curing procedure and sheeting should remain in place for at least 7 days.
Plastic sheets for curing
Construction Inspection and Testing
• Slump and cylinder strengths are not meaningful for pervious
concrete. Strength is a function of the degree of compaction,
and compaction of pervious concrete is difficult to reproduce
• A unit weight test is usually used for quality assurance, with
acceptable values dependent on the mix design, but generally
between 1600 kg/m³ and 2000 kg/m³
Post-Construction Inspection and
• After seven days, core samples can be taken and measured for
thickness and unit weight as quality assurance and
acceptance tests. A typical testing rate is three cores for each
• Compression testing for strength is not recommended,
because of the dependence of compressive strength on
• Maintenance of pervious concrete pavement consists
primarily of prevention of clogging of the void structure.
• Cleaning options may include power blowing and pressure
washing. Pressure washing of a clogged pervious concrete
pavement has restored 80% to 90% of the permeability in
• Pervious concrete in freeze-thaw environments must not
become fully saturated. Saturation of installed pervious
concrete pavement can be prevented by placing the concrete
on a thick layer of 200 to 600 mm of open-graded stone base.
• Reduces storm water runoff.
• Eliminates need for detention ponds and other costly storm
water management practices.
• Replenishes water tables and aquifers.
• Allows for more efficient land development.
• Minimizes flash flooding and standing water.
• Prevents warm and polluted water from entering streams.
• Mitigates surface pollutants.
• Light reflectivity is higher than with asphalt surfaces,
reducing any heat island effect.
• Runoff from adjacent areas onto pervious concrete needs to
• The parking areas are generally limited to auto parking and
• If reinforcement is required, epoxy coated bars should be
• Concrete is variable in permeability; over vibration
significantly reduces permeability.
• It is still a new material that requires acceptance from cities
• Pervious pavement
for parking lots.
• Alleys and driveways.
• Trees gates in sidewalk .
• Swimming pool decks.
• Tennis court.
• Greenhouse floors.