Research Activities
(A) Warm Mix Asphalt ( WMA ) Technology:-
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Warm Mix Asphalt technology is comparatively new in India in which an additive is mixed with hot asphalt mixes in desired proportion so as to lower down the hot mix temperature from 160° C to 135° C-140° C for preparation of workable mix for laying. This leads to considerable energy saving in addition to minimizing the emission of GHG gases. Such technology is also eco-friendly as use of energy is minimized to certain extent in addition of supplementing the strength in pavement so constructed.The use fo bitumen is also lowered down equal to quantity of additive and hence the process of WMA is comparatively economical.

Selection of Additive:-

Shell Thio-Pave is selected as an additive for use in asphalt paving mixture that can also significantly improve the mechanical performance of asphalt pavement. The IRC has also issued accreditation certificate to Shell – Thiopave materials vide their letter No. IRC- 24(12) / 2007(Acc-6) dt. 8.10.09.

About Thiopave:

Thio-Pave acts as both a binder extender, replacing upto 25% of the bitumen in an asphalt mixture with all equivalent volume of Thio-Pave as well as an asphalt mixture modifier, which can lower the compaction temperature of paving mixtures.

  • Thio-Pave comprises sulphur and a number of additives.
  • Thio-Pave pallet contains upto 3% carbon black which acts as a plasticizer for improved dispersion in the mixture and mixture workability.
  • Thio-Pave reduces emission of Hydrogen Sulphide (H2S) entrained in the Sulphur. Workability additive allows the asphalt mixture to be mixed at lower temperature than conventional asphalt, which limits H2S generation and saves energy in asphalt production.
  • Thio-Pave is generally used at high concentrations in the binder (30% by volume of the total binder), surplus Sulphur dispersed in the bitumen eventually precipitates to form Sulphur crystals and lattices, which stiffens the asphalt paving mixture at high service temperatures and under slow or stationary loads.
  • Binder content (Bitumen+thiopave) will remain the same by volume in comparison with conventional asphalt.

Application Process of Shell Thiopave –

  • Shell Thiopave pellets are added to the preheated aggregates and bitumen during the asphalt mixing process.
  • For a batch of 1800 kg of Dense bituminous macadam mix 1.65% of thiopave by weight of mix will be added in to the pug mill manually
  • The mode of additional will be through a chute fabricated on one side of pug mill .
  • Two bags of Thiopave @15 kg per bag shall be manually added.
  • Scaffolding arrangements will be made at 2 locations on site.
    • At HMA plant- for transport of bags to the first level of HMP
    • 100 m from HMP in the route of movement of Tipper for taking temperatures of mix.
  • The temperature window for Thiopave asphalt mix production will be strictly 135 ± 5° C.
  • At these temperatures the Shell Thiopave pellet quickly melts, is easily dispersed throughout the mix and does not extend mixing time.
  • Ensuring that the temperature of any mixture containing Shell Thiopave is less than 145°C is important to minimize gaseous emissions, primarily H2S and SO2 , during the production, laying and compaction work.
  • Operating at the low end of the temperature range reduces the likelihood of production and exposure to these gases, and reduces the amount of sulphur vapour created through the evaporation of molten sulphur as the mixture is being placed and compacted.

Experimental Stretch:-

The trial section was constructed in September 2010 on National Highway No. 3 near Nashik by Ashoka Buildcon Ltd under the guidance of AHRC and Shell Engineers into three section as under :-

(1) Thiopave + Thiopave DBM layer (km 429/595 to km 429/705)
(2) Thiopave + Conventional DBM layer (km 429/495 to km 429/595)
(3) Conventional + Conventional DBM layer (km 429/385 to km 429/495)

Scientist from Central Road Research Institute (CRRI) also visited the site during the construction of the Thiopave tests sections.The trial section pavement was evaluated after allowing the traffic on the trial section for about four months period.

Benkelman beam deflection studies were conducted on the test section, visual observation were also made by walking along the pavement test section and cores were taken using core cutting machine. The CRRI has also associated in the above processes.

Test Procedures:-

Following tests procedure was followed and testing data was tabulated to arrive at the conclusion

(1) Design of job mix formula for Dense Bituminous Macadam (DBM) with Thiopave.
(2) Trial stretches with the above job mix formula were constructed in September 2010 with association of Scientist from CRRI.
(3) Field core density test of bituminous material were taken in September 2010.
(4) Full traffic was allowed on test section for a period of about four months.
(5) Then after the Benkelman Beam deflection test were carried out on test track site and core samples were also collected for testing in the Laboratory in association with CRRI Delhi.
(6) The following analysis of test samples were carried out in Laboratory in association with CRRI.

  • Bulk density and Air voids
  • Marshal stability and indirect tensile strength (ITS)
  • Indirect Tensile Stiffness Modulus (ITSM)
  • Aggregate gradation of the core samples.
  • Corrected Characteristic Rebound Deflection Value.
(7) Conclusions drawn from the above experimental track with the help of test data :-
  • The Thiopave DBM mixtures have higher Marshal Stability values indicating that it is a rut resistant mixture.
  • The Marshal Stability values were 14 to 18 % higher with Thiopave DBM mixture when compared with conventional DBM mixture.
  • The Thiopave DBM mixture have highest stiffness value indicating better resistance to cracking and rutting compared to conventional DBM mixture.
  • Benkelman Beam deflection values showed that the Thiopave + Thiopave section had the least deflection value (0.548 mm) when compared with the other two sections showing better structural adequacy of pavement. The deflection value was decreased by 10 % with Thiopave in two layers of DBM (120 mm) when compared with two layers of conventional DBM (120 mm). Similarly the deflection values were decreased by 5 % with Thiopave in one DBM layer (60 mm) and one layer of conventional DBM (60 mm) when compared with two layers of conventional DBM (120 mm)
  • • Initial pavement evaluation results have shown encouraging results with Thiopave as a bituminous mixture modifier in DBM layers. Further periodic evaluation studies are necessary to completely assess the advantages of the Thiopave DBM bituminous mixtures under heavy traffic and varying climatic conditions.
(8) Application of Thiopave Technology in construction:-

In view of the value added benefits of Thipave additive in Hot Asphalt Mixes as observed from the above experiment, Ashoka Highway Research Center has recommended Ashoka Buildcon Ltd. to use the above technology on experimental basis on their Toll way work of NH3 from Pimpalgaon Nashik Gonde (km 380 to 440) which is under construction for the present. Accordingly ABL has taken decision to utilize Thiopave as an additive for Hot Mix Hot Laid DBM mixes for maximum portions of the balance work after due consent from Independent Consultants of NHAI . The observations & periodical testing on the trial length of NH3 will be conducted periodically in days to come so as to assess long term effects of Thiopave additive. Separate arrangements will be made during construction of the above trial length to measure the energy savings in using the Shell- Thiopave & will be made available after the construction is over.

(B) Green Highways:-
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Green highway technology was initiated in USA since the year 2002 and then after it is being persuaded in that country though public private participation, a social group, known as Green Highway Partnership (GHP). The nationwide group of GHP in USA has also identified the characteristics of Green Highway and rating system of Green Roads.

The AHRC intend to start the systematic educative social movement including applications of Green Highway technology wherever possible in India on the similar pattern of GHP in USA.

In pursuance of the above technology, the AHRC has undertaken the studies of Green Highway so as to formulate its general characteristics suitable to Indian environment and promote the use of Green aspects of the highway wherever possible. To work out more details on the subject and to formulate the action plan, it is proposed to constitute a Public Private Association in India viz. Green Highway Association India (GHAI). Such association and its branches at project level, Taluka level, District level, State level and National level shall work to promote the concept of Green Highway after formulating the characteristics and rating methodology for Green Highways.

Green Highway concept may go on developing in days to come depending upon Socio-economic priorities and research data that may come forth for adding or deleting in the present concept.

Ashoka Highway Research Center has undertaken the above work of implementing the concept of Green Highway in India and making available information on the subject to the concerned peoples & institutes including training to highway engineers.

Brief consideration for Green Highway:-

Green Highways constitute transportation functionally and ecological sustainability so that transportation requirements and environmental functions are better than before. The expected contribution of Green Highways include reduced use of virgin materials, reduced energy use, mitigation of environmental burden, promotion of human health and safety, optimization of habitat and land use, improve business and communication and most important is reaffirm our commitment to future generation also.

The traditional highway can be converted into green highway right from design process and shall undergo desired changes during construction and maintenance phases. Before the formulation of common characteristics of green highway it is always advantageous to understand the green practices to be followed during process of designs, construction and maintenance of highway. The below discussed green practices are not final and may change during days to come depending upon the research data that may come forth in this respect. Some of the practices may have to be replaced or some of the new practices shall have to be newly added depending upon social priorities and invented alternative practices in vogue at that time.

One more important aspect we have to keep in mind is that the green highway initiative is the voluntary social movement comprising Govt. authorities of highway Dept. Environmental and Ecological department, other concerned Govt. Dept. Social institutions, private contractors, labour unions and parties helpful in implementing the social goals of green highway. The green highway is not any Govt. stipulation of laws but the results of composite efforts rendered by public private associations. There are various Govt. stipulations and laws on minimum environmental requirements but we have to go much beyond these requirements and compliances so as to protect, as far as possible, the environmental and ecological process to its natural form without much impact of highway construction.

The GOI's ministry of environmental and forest has already framed several guidelines and environmental clearances as statutory requirements for highway projects. In this respect the water (Preventions and control of pollution) act 1977 including rules framed in 1978, the air (Preventions and control of pollution) act 1981, the hazardous waste (management and handling) rules 2000, mineral conservation and development rules 1988, the various mines and mineral acts, environmental protection act 1986, Natural wildlife action plan (2002), Nation forest policy (1988), National conservation strategy and policy, National Biodiversity strategy and action plan (2003), Statement on environment and development (1992), environmental legislation for protection of sensitive ecosystems and biodiversity resources etc, can be referred for minimum requirements under each such law related to environment. Environment and ecology are being commonly used terms. The biodiversity is the degree of variation of life forms within a given ecosystem. The some is a measure of the health of ecosystems. Biodiversity boosts ecosystem productivity where each species, no matter how small, have an important role to play. For example, a large number of plant species means a greater variety of crops, greater species diversity ensures natural sustainability for all life forms and healthy ecosystems can better withstand and recover a variety of disasters.

Identification of areas under green highway concept

Several technologies exist to reduce the environmental impacts of highway constructions. The use of advance planning, intelligent construction and efficient maintenance techniques shall have to be adopted into every modern highway design. User costs, energy consumption and long term environmental benefits shall have to be incorporated in highway designs. Green highways are relatively new concept eventhough several technologies involved in green highway design are in use since long in highway construction. The green highways (GHP concept in USA) majorly identify four areas to be developed i.e. watershed driven stormwater management, recycle, reuse and renewable materials conservation and ecosystem management and lifecycle energy of highways.

The brief description of each of the above area, to be developed to produce green highway, are given below.

1) Watershed driven stromwater management :

Watershed driven stormwater management is significant in reducing the stromwater runoff from a highway as well as treating the runoff by natural ways. Stormwater management is the techniques for holding and treating the runoff produced by a highway and diverting the stormwater runoff to areas where it can infiltrate to the ground water table. The green infrastructure practices protect runoff water quantity and quality in two ways. First they reduce the amount of pollutants at site and ultimately are discharged into adjacent water bodies. Secondly they reduce the water that runs off the site. Infiltration & evapotrianspirations of stormwater are two natural methods of stormwater treatment. The suitable methodologies for stormwater management within ROW shall have to be evolved considering the present practices.

In USA, technologies like bioretaintion (Landscape designed to remove silt and pollution from surface water runoff), pervious pavement shoulders, environ friendly concrete, forest buffers, restored and stormwater wetlands, stream restoration, soil amendments, wild life crossings etc. are being used. The field of watershed driven stormwater management is constantly evolving and need attention of researchers.

It is challenging job to researchers to develop suitable and economical tools which will aid in design & analysis of stormwater management and treatment alongside of highways.

The following few research opportunities in stormwater management are listed below which are also hinted for development in USA also

i) Cost-benefit analysis of maintenance practices of stormwater management (SM)
ii) Commonly applicable O & M practices for SM.
iii) Minimizing maintenance requirements of SM.
iv) Methodology of SM performance & designs.
v) Identification of critical needs within watershed for SM.
vi) Analysis of pollution reduction in water in SM.
vii) Cost-benefit demo for SM mitigation.
viii) Viable approaches to highway runoff management.

2) Recycle, Reuse and Renewable materials :

Recycling and reusing materials are both aimed at conservation of natural materials and reduction of waste during construction & maintenance of highways. But recycling and reusing are not the one and same activities. Recycling is process while reusing is practice. Making utilization of old railing, old kerb stone, reusing centering and scaffolding materials etc. are the examples of reuse.

The old B.T. pavement material can be recycled in the form of new pavement through specially designed plant. The industrial byproduct/ wastes can also be recycled in various items of highway construction viz. fly ash, blast furnace slag, foundry sand, waste rubber tyres & rubber pieces etc. Recycling involve comparatively more energy, because we have to reprocess an item into a new product.

Renewable materials can also be used in place of some non-renewable highway materials.

3) Conservation and ecosystem management :

Conservation and ecosystem management has vital role in minimizing effect that highway system on its surrounding ecology. Many aspects of the ecosystem are affected by the highway construction. The most obvious effect highway have on the natural eco system is the displacement and division of natural habitat. Maintaining natural flows of rivers, streams etc. without changing the gorge of flow at highway site contribute to conservation of ecosystem. Similarly ecosystem management shall also include the use of wildlife crossings at the highway site and wildlife buffer zones.

4) Life cycle energy of Highway :

Energy is an important economic concern and construction and maintenance of highway requires large amount of energy. The energy is also consumed by vehicles travelling on highways.

The reduction in life cycle energy consumption of highway is one of the object of green highway. To implement the objective, it is obvious to innovate the practices that will reduce lifecycle energy consumption of a highway. These practices shall work to reduce emissions also so as to minimize the air pollution.

The use of Warm Mix Asphalt (WMA) in lieu of Hot Mix Asphalt (HMA) is one of the practice to reduce the lifecycle energy in highway construction. The WMA consume considerably less energy than HMA due to lower production temperature in WMA.

Cement is also very energy intensive material which is being used extensively in highway projects. To minimize the cement use, research has been made to replace a large portion of cement by pozzolona, fly ash and byproducts from steel plants. It is interesting to note that use of one ton of fly ash as a substitute for one ton of cement in concrete can have a total primary energy reduction of 4695 mega joules or equivalent of energy used in burning 147 litres of gasoline.

The highway shall be designed in such a way that energy consumption can be reduced during construction of highways.

Designs consideration for green highway in highway projects :

The above discussions lead to formulate the designs considerations of green highway in practical form as under : i) Primary action plan shall have to be prepared while designing the green highway project so as to preserve and safeguard natural size, shape, flow of rivers, lakes and streams. Similarly natural beauty of environment i.e. forest, wildlife etc. shall have to be maintained without much disturbances.

ii) The proposal of minimum utilization of natural resources, materials and products shall have to be framed at designs stage only.

iii) The proposal of using Warm Mix Asphalt (WMA) in lieu of Hot Mix Asphalt (HMA) is to be considered at designs stage after considering quality of road, economical considerations and life of designed highway.

iv) The survey and provision of using fly ash &/ or other industrial waste products locally available for use in concrete/ asphalt roads shall have to be estimated at design stage of Highway.

v) The estimate of generation of useful milling materials while executing the project and proposal for utilization of the same for different areas viz. internal roads, service roads, on sides of road shoulders etc. shall have to be framed at design stage of the green highway.

vi) The economical aspect and methodology of effective stormwater management along road side shall have to be studied at design stage and appropriate provisions for management of stormwater within ROW shall have to be made in the project after requisite design.

vii) As far as possible planning of the highway shall be such that one time road construction activity can be planned so as to minimize the rework.

viii) While drafting designs proposals for concrete roads, asphalt roads and any other road materials, it is always advantageous to estimate the environmental damages of such proposals during execution so as to compare the same with minimum requirement as per Govt. stipulations for clearance of project.

Green Highway considerations at construction stage :

The designs considerations of green highway shall have to be well studied before the project put to execution and following aspects shall have to be strictly adhere to during execution so as to convert the highway project into green highway.

1) Reduce vehicle/ machinery fuel consumption & lower down fuel demand than estimated in actual construction.

2) Utilization of natural resources & virgin materials to bare minimum extent than estimated.

3) Recycling of byproducts and industrial waste viz.: waste rubber, fly ash, plastic, glass etc. in the locality shall be given priority.

4) Utilization of low electrical equipments viz. CFL, LED, LCD etc. on project site shall have to be ensured.

5) Selection and use of efficient construction equipments and plants which will help to reduce the pollution during construction. Monitor the performance of such plants periodically.

6) Utilization of natural and renewable energy source far camps, offices and execution site areas i.e. solar panels etc.

7) Minimize the waste of every kind. Disposal of hazardous and non-hazardous waste from construction site and reporting its environmental compliances to concerned authorities.

8) Utilization of spill control techniques and recycling techniques wherever possible.

9) Measuring & keeping record of environmental damages during construction phases in terms of air, water, land, flora, fauna & its special impact with sophisticated testing equipments.

10) It is most important to plant large canopy trees along both sides of highway. One should remember that one sqm. of green canopy absorb 0.2 kg of CO2 and other waste gases. Tree plantation interact the stormwater, mitigate the temperature, improve air quality and prohibit soil erosions. Maidan portions between lanes of highway shall also be used for plantation of herbs & shrubs so as to reduce CO2 and help to generate oxygen. Use more local species during the plantation which deliver more severity rate & reduce the rework of plantation.

11) It should be ensured that the compliances of environmental rules & regulations shall be much beyond the stipulated limitations.

Green Highway consideration during maintenance of highway :

1) Monitoring of plantation growth & implement techniques to increase the severity of plantations and survival ratio.

2) Monitoring ambient air quality & noise quality after construction.

3) The typical vehicles plying on the highway viz. S.T. buses, trucks, multi-axle vehicles etc. can be assessed for their life maintenance, fuel consumptions, travel life (in kms.) etc. so as to estimate the GHG emission by transportation system as a whole & methodology to reduce down the same and shrinking the related carbon footprints. The goal of sustainable transportation is to protect the environment & conserve natural resources while taking into consideration social need and cost- benefit ratio. The efforts shall have to made in association with transportation sector to reduce the emission of GHG and other detrimental foul gases that affect the environment.

4) Monitoring & minimizing highway accidents.

Characteristics of Green Highways :

The above data entail to arrive at tentative general characteristics of "Green Highway" initiative covering all the above aspects is general form, which can be made applicable all over the country for time being. These characteristics are not final and may go on changing in days to come depending upon the innovative practices and research on various aspects of "Green Highway" concept. The GHP in USA has also formulated the characteristics for green highways which are also taken into account while finalizing the below mentioned characteristics of Green Highway.

1) The environmental functions as were existing before the construction of Highway in the locality shall improve after the construction of green highway or it shall be better than before.

2) Watershed of the area shall have to be protected by green infrastructure so as to maintain its essential ecosystem role, ecological sustainability & environmental functions. Also to adopt green techniques for stormwater management along highway side and also within watershed so as to cleanse maximum runoff within the watershed of project area.

3) The environmental requirement as per the laws of the land are minimum standards. However the green highway approach goes for achievements beyond the minimum standards of prescribed regulations.

4) Maximize the use of recycled materials and minimize the use of virgin natural materials. Reduce the energy required to build the highway.

5) Plantation of large canopy trees and other plantations in available vacant land alongside the highway with local species.

6) Preservations and safeguarding of natural beauty of environment, rivers, lakes, forest and wildlife. Restore natural drainage paths to rivers, stream channels etc.

7) Reduce disruption to ecological processes and encourage smart growth by integrating and guiding future growth and capacity building with ecological constraints. Promote wildlife corridors and plan for conservation of wildlife.

8) Use of efficient and environmental friendly construction equipments and plants.

9) Calculations of environmental damages during construction phases in terms of air, water, land, flora and fauna & its social impact. Compare targeted environmental outcomes vis-à-vis local environmental needs.

Benefits of Green Highways:

Green highway is associated with a variety of social environmental, economic & human health benefits. The benefits of green infrastructure are particularly accentuated in urban & suburban areas where green space is limited & environmental damages are more extensive. Green infrastructure benefits include.

i) Social benefits :

Highway has an important impact on local economies. Highway can draw a business into local society & provide local jobs & tax income. Due to decrease of materials in land fill, the land fill space will be decreased ultimately reducing user costs for communities around the land fill. Reduction in noise and reduced pollution from highways can increase the quality of life in the area. Similarly other benefits viz. decreased water use, use of recycled materials, protection to wildlife, decreased amount of pollutants contained in surface runoff & increase in stream & recreational water quality etc. benefits can also be availed by the society.

ii) Reduced & delayed stormwater runoff volumes :

Green infrastructure techniques increase stormwater infiltration rates, thereby reducing the volume of runoff entering into sewer systems & ultimately at lake, rivers & streams.

iii) Enhanced groundwater recharge :

The natural infiltration capabilities of green infrastructure technologies can improve the rate at which ground water tables are 'recharged' or replenished. Enhanced ground water recharge can also boost the supply of drinking water for private & public uses.

iv) Stormwater pollutant reductions :

Green highway techniques infiltrate runoff close to its source & help to prevent pollutants from being transported to nearby surface waters. Once runoff is infiltrated into soils, plants & microbes can naturally filter & break down many common pollutant found in stormwater.

v) Reduced sewer overflow events :

Utilizing the natural retention & infiltration capabilities of plants & soils, green infrastructure limits the frequency of sewer overflow events by reducing runoff volumes & by delaying stormwater discharges.

vi) Increased carbon sequestration :

The plantation & soils which are the part of green highway approach serve as sources of carbon sequestration. In this process CO2 is captured & removed from the atmosphere via photosynthesis & other natural process.

vii) Urban heat mitigation & reduced energy demands :

In urban locality natural land cover is replaced by dense concentration of pavement, building and other surfaces that absorb and retain heat. The displacement of trees and vegetation minimizes their natural cooling effects. Additionally tall buildings & narrow streets trap & concentrate waste heat from the vehicles, factories & air conditioners. By providing increased amount of urban green space & vegetation, green infrastructure can help to mitigate the effects of urban heat & reduce energy demands. Trees and other green infrastructure can also lower down the demand for air-conditioning energy, thereby decreasing emissions from power plants.

viii) Improved air quality :

Green infrastructure facilitates the incorporation of trees & vegetations in urban landscape. This can contribute to improved air quality. Trees & vegetation absorb certain pollutants from the air through leaf uptake & contact removal. If widely planted throughout the habited areas, trees & plants can even cool the air & lowering down the temp. dependent reaction that form ground level ozone pollution.

ix) Additional wildlife habitat & recreation space :

Greenways, parks, urban forests, wetlands & vegetated swales (bioretaintion places) are all forms of green infrastructure that provide increased access to recreational space & wildlife habitat.

x) Improved human health :

Vegetations & green space can have a positive impact on human health.

xi) Increased land value :

Clean & green infrastructure can increase the value of surrounding properties.