Provisions of Rigid, Semi Rigid and Flexible Pavements as Rural Roads


Provisions of Rigid, Semi Rigid and Flexible Pavements as Rural Roads

In near future, the cost of bitumen will go on increasing. So, various alternates to construct the roads are to be explored. Though concrete roads are one of the good alternates, but still their use is limited. This paper discusses the merits and demerits of all types of pavements construction and proposes their optimum use.

Dr Praveen Kumar, Professor, Transportation Engineering Group, Civil Engineering Department, IIT Roorkee. Ankit Gupta, IIT Roorkee.

Introduction

Development of a country depends on the connectivity of various places with adequate road network. Roads are the major channel of transportation for carrying goods and passengers. They play a significant role in improving the socio-economic standards of a region. Roads constitute the most important mode of communication in areas where railways have not developed much and form the basic infra structure for the development and economic growth of the country. The benefits from the investment in road sector are indirect, long-term and not immediately visible. Roads are important assets for any nation. However, merely creating these assets is not enough, it has to be planned carefully and a pavement which is not designed properly deteriorates fast. India is a large country having huge resource of materials. If these local materials are used properly, the cost of construction can be reduced. There are various type of pavements which differ in their suitability in different environments. Each type of pavement has it’s own merits and demerits. Despite a large number of seminars and conference, still in India, 98% roads are having flexible pavements. A lot of research has been made on use of Waste materials but the role of these materials is still limited. So there is need to take a holistic approach and mark the areas where these are most suitable.

Types of Pavements

There are various type of pavements depending upon the materials used. A briefs description of all types is given here.

Flexible Pavements

Bitumen has been widely used in the construction of flexible pavements for a long time. This is the most convenient and simple type of construction. The cost of construction of single lane bituminous pavement varies from 20 to 30 lakhs per km in plain areas. In some applications, however, the performance of conventional bitumen may not be considered satisfactory because of the following reasons:
  1. In summer season, due to high temperature, the bitumen becomes soft resulting in bleeding, rutting and segregation finally leading to failure of pavement.
  2. In Winter season, due to low temperature, the bitumen becomes brittle resulting in cracking, raveling and unevenness which makes the pavement unsuitable for use.
  3. In rainy season, water enters the pavement resulting into pot holes and sometimes total removal of bituminous layer.
  4. In hilly areas, due to sub zero temperature, the freeze thaw and heave cycle takes place. Due to freezing and melting of ice in bituminous voids, volume expansion and contraction occur. This leads to pavements failure.
  5. The cost of bitumen has been rising continuously. In near future, there will be scarcity of bitumen and it will be impossible to procure bitumen at very high costs.
Recently, a large number investigations have demonstrated that bitumen properties (eg. viscoelsticity and temperature susceptibility) can be improved using an additive or a chemical reaction modification.

Provisions of Rigid, Semi Rigid and Flexible Pavements as Rural Roads

The use of polymer modified bitumen's (PMBs) to achieve better asphalt pavement performance has been observed for a long time. The improved functional properties include permanent deformation, fatigue and low temperature cracking. The properties of PMVs are dependent on the polymer characteristics and content and bitumen nature, as well as the blending process. Despite the large number of polymeric products, there are relatively few types which are suitable for bitumen modification (2). The polymers that are used for bitumen modification can be divided onto two broad categories, namely plastomers and elastomers. Elastomers have a characteristically high elastic response and, therefore, resist permanent deformation by stretching and recovering their initial shape. Plastomers from a tough, rigid, three dimensional network to resist deformation. The thermoplastic rubber, styrene butadiene-styrene (SBS), is an example of an elastomer and the thermoplastic polymer, ethylene vinyl acetate (EVA), is an example of a plastomer. One of the principal plastomers used in pavement applications is the semi-crystalline copolymer, ethylene vinyl acetate (EVA). EVA polymers have been use in road construction for more than 20 years in order to improve both the workability of the asphalt during construction and its deformation resistance in service. Figure 1 to 6 show the effect of these modifiers to bitumen before and after ageing.

Semi Rigid Pavements

The pavements constructed using the waste materials, which are more strong the traditional aggregates may be treated as Semi-Rigid Pavement. A lot of research work has been done in this direction. But the work in terms of real construction is not visible.

Some examples of real construction are given below:

Provisions of Rigid, Semi Rigid and Flexible Pavements as Rural Roads

Visakhapatnam Steel Plant (VSP) at Visakhapatnam (AP) is one of the major steel plants producing steel in the country. Granulated Blast Furnace Slag (GBFS) is also generated as a by-products of steel. Prior to 1991, a major portion of GBFS was being used by the cement manufacturing industries located in the nearby areas but its utilization in this industry has been decreasing gradually. This material has, therefore, been piling up gradually due to increased production as a waste in the plant area an posing serious problem for its disposal. Two roads namely Ankapalli-Pudimadaka Road (AP road) – a MDR and Bheemunipatnam-Narsipatnam road (NB road) – a State Highway were selected for test track construction. The existing width of the road pavement was about 3.5m and as per state PWD programme, has to be increased to 5.5m by 1m widening the carriageway on both sides of the road. The pavement thickness worked out to be 425mm for the traffic parameter of 3 million standard axle (msa) for BN road and 480mm for the traffic parameter of 1.25 msa in case of AP road. The pavement compositions were then, worked out considering the strength of GBFS, GBFS subgrade soil/moorum mixes for the two roads.

In another project, Conventional moorum, gravel, sand or lime/cement stabilised local soil were used in subbase layer of a road pavement. In order to compare the structural performance of these materials with the steel industry wastes, a small test track was constructed at Bokaro. The selection of different test sections was made on the basis of laboratory test results as discussed in the previous sections. The details of the test sections are as follow:

Provisions of Rigid, Semi Rigid and Flexible Pavements as Rural Roads

In order to structurally evaluate the different specifications/test sections, plate load tests were conducted on each section using a 30cm diameter plate. The load deflection values were recorded by applying incremental load. Plate load test was also carried out on subgrade soil. Since with an ordinary truck, only limited magnitude of reaction can be obtained, a heavy 35 tonnes dumper was used for carrying out place load test. Based on Burmister's two layer theory, the modulus of elasticity for different specifications were worked out and are given in Table-2. The ratings based on load carrying capacity of different sections are also indicated in the same table.

Provisions of Rigid, Semi Rigid and Flexible Pavements as Rural Roads

Similarly, Bandamunda Jaraikala road, which is a major district road near Rourkela, was chosen for construction using the waste material from Rourkela Steel Plant. For the experimental test sections on Bandamunda Jaraikala Road, Rourkela. Where 1.8m widening on both the sides of the existing road was proposed, a total number of 11 test sections using steel plant wastes were laid. During rainy season, heavy rains are there and water passes across the road. While formulating specifications, attempts were made to make maximum utilization of steel plant by-product such as BF slag, SMS, granulated slag and flyash, etc. It includes one control test section, which comprises conventional road building materials for comparison purpose. It shows that except right portion of sections 1,2 all sections were structurally sound after two months of construction.

Rigid Pavements

Provisions of Rigid, Semi Rigid and Flexible Pavements as Rural Roads
Rigid pavements, though costly in initial investment, are cheap in long run because of low maintenance costs. There are various merits in the use of Rigid pavements (Concrete pavements) are summarized below:
  1. Bitumen is derived from petroleum crude, which is in short supply globally and the price of which has been rising steeply. India imports nearly 70% of the petroleum crude. The demand for bitumen in the coming years is likely to grow steeply, far outstripping the availability. Hence it will be in India's interest to explore alternative binders. Cement is available in sufficient quantity in India, and its availability in the future is also assured. Thus cement concrete roads should be the obvious choice in future road programmes.
  2. Besides the easy available of cement, concrete roads have a long life and are practically maintenance-free.
  3. Another major advantage of concrete roads is the savings in fuel by commercial vehicles to an extent of 14-20%. The fuel savings themselves can support a large programme of concreting.
  4. Cement concrete roads save a substantial quantity of stone aggregates and this factor must be considered when a choice pavements is made,
  5. Concrete roads can withstand extreme weather conditions – wide ranging temperatures, heavy rainfall and water logging.
  6. Though cement concrete roads may cost slightly more than a flexible pavement initially, they are economical when whole-life-costing is considered.
  7. Reduction in the cost of concrete pavements can be brought about by developing semi-self-compacting concrete techniques and the use of closely spaced thin joints. R&D efforts should be initiated in this area.

Concrete Pavements-Why and Why Not?

Despite the above facts, long time research and high level well wishers concrete roads are still only 2% in the country. Every years, there are many seminars in the country which give emphasis over the use of Concrete roads. In PMGSY also, a separate code has been issued to design the concrete roads. But the percentage of concrete roads is less than 2% in this Yojna also. First of all it is to be understood why concrete roads fall?
  1. Concrete required even days curing. At least for one day, nothing should ply over the pavement. But in actual, people feel that it wastage of their time. So like on bituminous pavements, they start playing the vehicles over concrete pavements also.
  2. Some researchers have proposed thin bituminous section without using steel in it. Such sections may suit thin lanes where only scooters or cars are plying but on rural roads or highways, where there is no control over loading, these concrete roads are bound to fail.
  3. Concrete roads cannot be compared with concrete beams, columns or slabs where sufficient curing time is available and the load over that comes after gaining sufficient strength.
So considering the above facts it can be concluded that Concrete roads should not flagged as cheaper roads. Rather they should be announced as good roads. If one has sufficient funds and he traffic can be diverted for sufficient time only then, concrete roads will go on failing and blame will go to the technology rather than construction deficiencies.

Conclusions

Based on the above discussion, following conclusions are made:
  • Concrete roads are good roads but not cheaper roads. These roads should be considered only if sufficient funds are available. The thickness of the pavement and the reinforcement should not be compromised.
  • Semi Rigid pavements should be constructed in nearby areas of steel plants where these materials are available free of cost. In this regard, Government may pass an ordinance for compulsory use of these materials in such areas.
  • Bitumen is going to more costly in future. So it should be used very judiciously. Modification like CR, EVA and SBS may be used to reduce the susceptibility of the bitumen. It will reduce the quantity of bitumen also.

Reference

  1. Kumar Praveen, Kumar Ashwani, Dhawan, P.K. and Murty, A.V.R., Performance of Granulated Blast Furnace Slag in Road Construction – A Case Strudy, Indian Highways, July 1999.
  2. Kumar Praveen, Mehndiratta H.C. and Kumar Anant, "Economic Analysis of Rural Road Construction Under PMGSY" Indian Highways, Indian Roads Congress, Vol 133, No. 8 August 2005, pp 21-33.
Click Here
To Know More or to Contact the Manufacturer
Please let us know your name.
Invalid Input
Please let us know your Designation.
Please let us know your Contact Number.
Please let us know your email address.
Please brief your query.
Our other Value-Added Services:

To receive updates through e-mail on Products, New Technologies & Equipment, please select the Product Category(s) you are interested in and click 'Submit'. This will help you save time plus you will get the best price quotations from many manufacturers, which you can then evaluate and negotiate.

Invalid Input
Invalid Input
Invalid Input
There are many challenges being faced by the highway sector such as ensuring availability of construction materials and machinery, timely completion of projects, availability of trained human resources

Read more ...

Practical Recommendations for Construction of Longitudinal Joints in Hot Mix Asphalt (HMA) Pavements Rajib B. Mallick, Ralph White Family Distinguished Professor, Civil and Environmental Engineering, Worcester Polytechnic Institute (WPI), Massachusetts, USA, and Veeraragavan

Read more ...

Plant and Equipment Determine Quality of Road Construction Road Infrastructure projects are time constrained; early completion of project entitles rewards while delays attract penalties. The plants and equipment being used determines the quality of the road

Read more ...

New Road Technologies & Smart Roads The exponential increase in the number of vehicles on roads has led to multiple traffic problems and associated risks, traffic congestions, etc., yet the roads, despite being arteries of modern

Read more ...

Designing roads and highways efficiently with the right materials will help achieve optimum construction cost, lower maintenance, and reduce life cycle costs. Ash from coal-fired thermal power

Read more ...

Rodic Consultants has emerged as a leader in the infrastructure consulting space with state-of-the-art engineering solutions, and a proven track record of timely completion of projects across sectors

Read more ...

Readymade Kandhal Pothole Patching Mix was adopted as Indian Roads Congress (IRC) Standard Specification IRC: 116-2014 for Readymade Bituminous Pothole Patching Mix Using Cut-Back Bitumen. All concerned

Read more ...

The Bundelkhand Expressway is a 296-km long, 4-lane wide (expandable to 6 lanes) access-controlled expressway in the state of Uttar Pradesh. It will connect Gonda village in Chitrakoot district with Agra–Lucknow

Read more ...

This case study briefly discusses the planning, design and construction of Package 3 of the Purvanchal Expressway. Package-3 of the Purvanchal Expressway is a 41.7km long section of the 340.82km long

Read more ...

Since the 1980’s billions of dollars have been invested in developing methods to make pavement design and construction more sustainable through the re-use of existing resources. This includes insitu recycling and

Read more ...

India has the second largest road network in the world, spanning a total of 5.89 million km, transporting 64.5% of all goods in the country. Nearly 90% of India's total passenger traffic uses the road network to commute

Read more ...

India generates nearly 26,000 tonnes of plastic waste every day, making it the 15th biggest plastic polluter globally. Discarded plastic waste litter the country’s roads, rivers and also form huge mounds in garbage

Read more ...

According to Vipula Sharma, Director – Ratings, Brickwork Ratings, with the recent tweaking in the HAM model, the share of the projects awarded under HAM model is expected to increase. “Overall, there should be a

Read more ...

After creating a world record for laying Pavement Quality Concrete (PQC) for a four-lane highway of 2,580 meters length within 24 hours, NHAI has made yet another record by completing a single lane of the four-lane

Read more ...

Ashoka Buildcon, a leading highway player in India, has an impressive portfolio of 39 PPP projects, which is the largest in number in the country. With 40 years of experience in the core business of Highway Construction

Read more ...

Patel Infrastructure, an established construction, development, and maintenance service company and a NHAI contractor, has created a world record in the Infrastructure sector by laying Pavement Quality Concrete (PQC) for

Read more ...

Macro synthetic polymeric fibres have the potential to enhance the post cracking properties of hardened cement-based materials, besides bringing improvements in other properties such as durability. This article disseminates

Read more ...

High altitude areas which are subjected to heavy snowfall and frost action necessitate special consideration for design and construction of pavements. U.K.Guruvittal, Chief Scientist & Dr G Bharath, Scientist, CSIR-Central

Read more ...

Flexible pavements are the most common type of pavement systems in the country. In addition to being convenient to construct, they are also cost-effective and easy to maintain. These pavements constitute the surface

Read more ...

Roller Compacted Concrete is an innovative technology gaining popularity in the recent past due to some of the positive points like low cost of construction, speed in construction, and the possibility of using mineral

Read more ...

×
Sign-up for Free Subscription
'India Construction Week'
Weekly e-Newsletter on Construction Industry
Get the latest news, product launches, projects announced / awarded, government policies, investments, and expert views.