Green technologies like pervious concrete and porous asphalt are being increasingly used in road construction in India. Pervious concrete allows water to pass through, reducing runoff. It consists of cement, coarse aggregates, and admixtures with high porosity (16% void space). Porous asphalt also has high porosity and consists of layers of asphalt, crushed aggregates, and geotextile. Both technologies reduce stormwater runoff and promote groundwater recharge compared to conventional pavements. They also provide environmental, economic, and safety benefits.

1. GREEN TECHNOLOGY IN
ROAD CONSTRUCTION
Shubham Singh
16CM22F
NITK
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2. Green Technology Adoption
Pattern In India
• The recent trend in India suggests a rapid adoption of
green technology in construction. Out of 85
internationally registered projects under LEED NC-USA,
32 (37 percent) are registered in India (USGBC, 2007).
More than 50 projects have been registered or certified
under the green building guidelines developed in India
(IGBC, 2007).
• Indian Green Building Council (IGBC) and LEED India has
framed guidelines according to the Indian context for
green construction and certification and therefore will
be compatible to the Indian construction practices.
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3. Green Technology
• Reduce, Reuse, Recycle and Renewable.
Structural or civil
techniques:
Electrical techniques Special systems
techniques
 Insulated wall
 Green cement
 Fly ash bricks
 Transparent roof
 Green roof
 Optimum use of natural light
 Replacing incandescent lamps
by compact fluorescent lamps
(CFL)
 Replacement of conventional
fluorescent lamp by energy
efficient fluorescent lamp/LED
 Solar lighting
 Solar wind hybrid
 Grey water by
evapotranspiration
 Rain Water
Harvesting
 Porous pavement
blocks
 Passive solar
design
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4. Pervious Pavements
• Low impact development (LID) is an approach to
managing storm water runoff to protect water
quality.
• 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)
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5. How does Porous Pavement
helps
• Environmental - reduced storm water runoff, recharge
groundwater, efficient land use by reducing the need for
retention ponds.
• Economic - the management effort made in preventing
excess runoff during heavy rainfall is prevented. Reduces
cost to maintain large detention ponds.
• Safety - increased safety for drivers, improves driving in
wet weather conditions, reduces night time glare and
lessens the risk of hydroplaning.
• LEED Credit - American rating agency to evaluate the
environmental performance of a building. Gain in credit
with the help of storm water design, water efficient
landscaping, recycled content, regional materials.
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6. Categories of Pervious Paving
Surfaces
• Porous Asphalt - very small proportion of ne
aggregates, interconnected void space provides the
permeability characteristics, can withstand repeated
traffic.
• Pervious Concrete - concrete with permeable spaces.
• Single-size aggregate - used without any binder, least
expensive, high utility in areas with low traffic
conditions like parking stalls.
• Porous turf - used in parking, counteracts “heat
island” with water transpiration.
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7. Porous Asphalt
Design
• Porous Asphalt consist of at least four layers
 a 2-4 inch layer of asphalt
 a 1-2 inch filter layer of 1/2 inched crushed aggregate
 a minimum 12 inch reservoir layer of 1-3 inch aggregate
 a layer of geotextile material
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8. Porous Asphalt
Design
• the void space of porous asphalt is approximately 16%,
as opposed to 2- 3% for conventional asphalt
• the crushed aggregate filter layer aids with pollutant
removal
• treated runoff is stored in reservoir layer, a highly
permeable layer of open-graded clean-washed aggregate
with at least 40% void space.
• nonwoven geotextile material placed between reservoir
bed and uncompact subsoil prevents migration of fines
into the stone reservoir which could clog the system.
• the treated water then percolates through the subsoil to
recharge the groundwater supply.
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9. Porous Asphalt
Performance of Porous Asphalt
• contaminants on the surface of pavement tend to
become part of runoff but with porous asphalt, they ow
down to the soil, where beneficial bacteria and other
natural processes cleanse them.
• open-graded asphalt roads have shown lower night
time surface temperatures as compared to impervious
pavements.
• benefits include noise reduction, a decrease in splash
and spray kicked up by vehicles in heavy downpours.
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10. Pervious Concrete
Design and Materials
Fine aggregate typically is eliminated, and the size
distribution of the coarse aggregate is kept narrow to allow
little particle packing.
• Cementitious Materials: Portland cements, blended
cements, supplementary cementitious material like fly ash,
pozzolans and slag can be added.
• Aggregate: narrow grading. Larger aggregates provides a
rougher surface. Both rounded aggregate (gravel) and
crushed aggregate(stone) have been used.
• Water: water-cement ratios of 0.27 to 0.34 are commonly
used along with addition of proper chemical admixtures.
• Admixtures: Because of rapid setting time associated with
pervious concrete, retarders or hydration-stabilizing
admixtures are commonly used.
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11. Pervious Concrete
Structural Design Concepts
• Subgrade and Subbase Soils: should normally provide a
6-12 inch layer of permeable subbase. Offers good
support values.
• Traffic Loads: truck traffic impact pavement much
more than cars, the estimate of trucks using the
pervious concrete pavement is critical to designing a
long life pavement.
• Other Design Factors: terminal serviceability, load
transfer at joints (aggregate interlock) and edge
support.
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12. Pervious Concrete
Hydrological Design Concepts
• Runoff Characteristics: Estimating volume and rate of runoff.
• Infiltration and runoff: both depend on soil type. Runoff is
also dependent upon the slope of land, extent of vegetation.
The infiltration will vary with the amount of moisture already
in soil.
• Permeability and Storage: excess surface runoff must not
result due to lower permeability or inadequate storage.
Generally permeability is not a limiting criteria since
permeability is mostly higher than the infiltration rate.
• Storage capacity: capacity of pervious concrete pavement
plus that of base course. The capacity of pervious concrete
depends on the effective porosity (that portion that can be
readily filled in service).
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13. Pervious Concrete
Hydrological Design Concepts
• Effect of Slope: if the slab is not levelled, the rainfall
will quickly run to one end of the slab and after some
time will overflow limiting the beneficial effects of
pervious concrete. The depth of pervious concrete or
rather just the thickness of base course increased to
accommodate desired runoff goals.
• Design Storms: storms are designated by their `return
periods'. `20year storm' will be larger than a `10year
storm'. Selection of Appropriate Return Period: one of
primary concern is water quality, pervious pavement
often designated to capture `2year storm'. When flood
control is a major issue, performance checked `10year
storm'.
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14. Pervious Concrete
Construction
• Subgrade and Subbase preparation: uniformity of subgrade
support. Since pervious pavement contains minimal water and
high porosity, care required to prevent premature dry out.
• Batching and Mixing: requires tighter control of mixture
proportioning to extract useful properties of impervious
pavement. Water content is limited to narrow range to provide
adequate strength and permeability.
• Transportation: low slump may make discharge from transit
mixers slower than conventional concrete.
• Placement and Consolidation: Placement should be continuous,
and spreading and strike off should be rapid. Because of rapid
hardening and high evaporation rates, delays in consolidation
can cause problems.
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15. Pervious Concrete
Construction
• Joint Placement: joint spacing is usually larger than
conventional pavements since pervious concrete shrinks
less. Joint installation should be soon after the
consolidation.
• Finishing: For majority of pavements finishing step is
`compaction'. This leaves a rougher surface but can
improve traction.
• Curing and Protection: the open structure and rough
surface makes curing more essential.
• Opening to traffic: it is generally recommended that the
pavements are opened for construction or traffic load
not before 7 days. Continuous curing is recommended
until the pavement is opened.
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16. References
• IGBC (2011), ―Indian Green Building Council: LEEDw-NC
India‖, available at: www.igbc.in
• Khosla,Radhika "Constructing Change: EnergyEfficiency
and India's Buildings Sector, The HinduBusiness Line,
January 2012
• IGBC Green Homes Rating System Version 2.0 , Abridged
Reference Guide 2012 , available at www.igbc.in
• S Shrinivas, Green Building Movement In India By,
Principal Counselor, CII -Sohrabji Godrej green Business
Centre, 2005
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