Dr. S. S. Seehra, Chief Pavement,Materials & Geotech Engineer, Span Consultants Pvt. Ltd. New Delhi

Introduction

Connectivity between towns, cities and different areas is an essential component in the development of a Nation. Roads and Railways provide this connectivity. High speed road corridors have been one of the most vital infrastructure in the overall socio–economic development of the country. In the past few years Government of India has taken up development of this important infrastructure on priority basis in a big way and the national road network has improved a lot when compared to the situation a decade ago. The network of existing highways and expressways is now showing signs of premature failure due to cumulative effect of inadequate maintenance and structural inadequacies to cater the need of increased traffic volume and heavy axle loads.

In many situations lack of proper drainage is the principal cause for the failure of the highway pavement structure. The maintenance funds for highways allotted by the central and state governments has been reducing and due to this reduction of available fund the task of preserving and maintaining highway assets is becoming increasingly complex and difficult.

The life of an infrastructural asset can be preserved and its life can be prolonged if adequate repair and maintenance is undertaken at proper time on regular basis. Proper design, regular periodical inspection and upkeep of drainage system are of utmost importance in preserving the huge investment made on construction of high speed highway corridors.

Due to abundance of good quality cement currently sweeping across the country, the stress is not getting shifted towards the cement concrete roads over the black top bitumen concrete roads.

On an overall basis the total transportation system in the country is to be expedited more towards ‘4 R’ type activities i,e.
  • Resurfacing
  • Restoration
  • Rehabilitation
  • Reconstruction
Most of the activities in field of existing highways may fall in one of the above. Necessity of repairs to cement concrete road pavements arises either from faults/imperfections in workmanship during construction (due to poor quality of manpower engaged or faulty equipment) or as a result of subsequent damage or deterioration. Recent developments in field of materials like thermosetting synthetic resins of epoxy and polyster type can be successfully used for repairs of cement concrete roads/pavements and these can be opened to traffic within a short period of 12 hours. For repairing the cracks in cement concrete pavements molten sulphur can be used. Magnesium phosphate cement (MPC) has a special rapid setting quality hence can yield high strength cement mortar which has been found suitable for use in emergency repairs of existing cement concrete roads/pavements. Traffic can be allowed on such repaired surfaces including large areas or small patches after 4 to 6 hours of repairs.

Defects in Rigid and Flexible Pavements

The main surface defects in Rigid and flexible pavements can be listed as:-

Rigid Pavements
  • Potholes
  • Scaling
  • Blowups
  • Mud Pumping
  • Spalling
  • Loss of sealent
  • Creacking (Longitudinal,
  • Transverse reflection
  • Sympathetic Corrugation etc.
Flexible Pavements
  • Potholes
  • Raveling
  • Slippery surface
  • Wheel track rutting
  • Distortion
  • Slippage
  • Corrugation
  • Shoving
  • Upheavals
  • Edge breaking
  • Streaking
  • Deformation
  • Stripping disintegration
  • Fatty surface
  • Hungar surface
  • Cracking etc.

Pavement Management System (PMS)

Unfortunately in India, we construct and forget our infrastructural assets. This truth is also applicable to our roads. We build roads and remember them only when they reach in extremely bad condition. The pavement management system and the systematic approach contained in this is not adequately implemented for repairs and rehabilitation. Non compliance result into heavy losses, discomfort, Mechanical damages in vehicles and loss of man hours. In many cases the high speed corridor pavements have failed prematurely in the absence of adequate maintenance during the design life itself.

Reconstruction

Many times the existing pavements are so extensively damaged that their rehabilitation may cost as good as for a new one. Hence whenever the existing pavements are in badly distressed conditions these are reconstructed using either of the two methods:
  • The existing pavements are removed, the recovered material is recycled and used as a fill material in filler course, sub– base or as aggregate for the new pavement.
  • The new concept in reconstruction of concrete pavement in future is roller compacted concrete pavementand its applicability to high density corridors as a lower layer comprising of DLC and top wearing course as PQC when laid with sensor slip form paving machines.

Emerging Repair Materials

Several new repair and construction materials are emerging as suitable repair materials for Flexible and Rigid pavements.

For rigid pavement:
  • High strength and high performance concrete (HPC) using flyash and silica fume.
  • Synthetic Resins, Magnesium phosphate cement, Magnesium Oxide Chloride cement, Sealents–Silicon and Polyurethane sealants, Sulphur and sand Mortars– Additives for obtaining very high strength Silicophosphate cement.
For Flexible pavements
  • Sand Asphalt base course
  • Bituminous cold mixes including gravel mix
  • Stone mastic, Fog spray, Liquid and slurry seals etc.

Strategic Repair & Rehab Technologies

Engineering departments and the government administration handling construction and maintenance of Road in India has a general tendency to build pavements and forget these. No proper monitoring, No proper maintenance, not enough funds for maintenance generally pose serious problems in maintaining durable and good roads. Reconstruction as a form of rehabilitation for highway concrete pavements continue to deteriorate and demand enhanced maintenance costs. Advances have been made in recent years in the development and use of quick setting and rapid hardening materials for use in repair and rehabilitation concrete pavements.

Figure 1 (a), Figrue 1 (b) shows cracking patterns of pavement slabs and faulting of concrete pavements slabs. Figure 1 (c) shows schematic diagram for reflection cracking Figrue 2 shows repair techniques for concrete pavements involving Surface preparation, Preparation of surface groove for resin repairs of pop–outs, potholes, corner and edge spalling etc.

Figure 3,4,5&6 show repair technique steps for prepration of surface pavement jacking bycement: flyash group and vaccum grouting with epoxy grout.

Photo No. 1 to 8 show various stages for pavement maintenance – Rigid and Flexible both types.

Highway Design and Maintenance Standards

World Bank has developed highway design & maintain standard model in version 3 (HDM-3) at present in use. HDM-4 has also been developed and released for use. HDM-4 has been caliberated for Indian deterioration and users cost models and customized for the chosen computer system platform which will bring the planning process to the state of art level. National highway network maps can be designed using survey of India base maps and mappingdata can be held in Geographic information system format in a cartographic database for road condition and road inventory surveys.

The entire highway management system needs to be established on a computer system platform on client server model at MORT4 ministry of road Transport & highways.

The consortium of consultants could be required to develop the system on a turnkey basis and hand it over to the MORT4 after operationalising it.

Guidelines for Strategic Maintenance

There is a dire need of the guidelines for the strategic maintenance of Rigid and Flexible pavements in India. Guidelines should be easy to understand & use must be cost effective and provide uniformity in evaluation, Process and management methodology. Cost comparison of repair and maintenance techniques is best made using equivalent annual cost and expected life of the repair materials used for a specific job.

Conclusions

The traffic on all national highways is likely to increase enormously in the future. To meet the demand optimally and thereby to ensure rapid economic progress of the country, it is essential to develop and establish an efficient highway planning and management system. Effort is also required to integrate various systems related to highway management carried out in India and in other countries. Maintenance by Contract for National Highways and expressways should be privatized or it should be made a part of the construction contract to reduce financial burden on the exchequer we should follow up strict construction supervision and stringent quality control measures and must protect national investment with minimum maintenance expenditure.

Proper pavement designs, regular periodical inspection, follow up for the inspection recommendations and proper maintenance of drainage system are of utmost importance in preserving the investment made on construction of highways at National, state or even at District levels Proper and well planned highway maintenance strategies would be useful to reduce the losses incurred due to bad conditions of roads.

Recommendations

After carrying out the pavement assessment and evaluation strategic maintenance and rehabilitation should be seriously considered, including full depth joint sealing, sub-surface drainage, repairing of all cracks, proper repairing of all spalled joints, Grout jacking of slabs and reconstruction etc. All patches shall preferably be repaired to full depth. Misaligned dowel bars can create higher load transfer stresses at joints hence proper care should be taken. 'D' cracking of slabs is caused by poor quality aggregates that absorb water and swell on freezing near joints. This result in cracking of slab resulting severe and rapid loss of pavement serviceability.

Pumping cause significant loss of pavement serviceability and could be reduced by providing and maintaining sub drainage.

Dowel bars, 35 mm diameter at 300 mm centers are recommended for preventing occurrence of faulting. The chloride and sulphate contents in concrete used for rehabilitation and repairs should not exceed 0.15% and 4.0% by weight of cement. Use of high performance concrete or Portland slag cement is recommended for maintenance of concrete roads specially in coastal areas.


At present, it is assumed that strategic operational maintenance costs of flexible pavements are approximately equivalent to the rigid pavements. Currently, there is not sufficient date vailable in the cost accounting system to determine with good reliability if there is any difference. It is recommended that selected pavement types for high speed corridor segments be identified and moniterad for operational maintenance costs. This data will help future activities. Repair and maintenance of pavements in heavy traffic areas is a very serious concern of the motorists using these corridors during routine maintenance and due importance should be given to this aspect while planning repairs/ maid.

An economic formula should be used to compare the cost of pavement options on an annual maintenance cost per km basis for high speed corridors.
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