Introduction
Regardless of the quality of pavement material and design, increase in vehicular traffic and changing environmental conditions will reduce the service life of pavements and ultimately result in their failure. The causes and types of failure of pavements in general and rigid pavements, in particular, should be understood in order to initiate proper repair and rehabilitation programs to enhance their service life. Repair and restoration of rigid pavements depend upon the type of distress. Cracking is the most common feature of the rigid pavement, while fatigue cracking is considered the major cause for its failure.
The stress ratio between flexural tensile stress and modulus of rupture of concrete is the primary factor that decides the number of road repetitions to cause fatigue cracking. Pumping, faulting, spalling, shrinking, polished aggregate, pop outs, deterioration of joint load transfer system, linear cracking, durability cracking, corner break, alkali-aggregate reaction and blow-ups are some of the causes of failure of rigid pavements.
Crack filling, Crack sealing, Diamond grinding, Dowel bar retrofitting, Joint repair, Partial depth repair and Full-depth repairs, Hard concrete surface texturing etc. are the most common techniques used for rehabilitation or restoration of rigid road pavements.
The rapid growth in rigid road construction brought about considerable expansion of road infrastructure, which subsequently fell into disrepair through lack of maintenance. The damage is often so severe that ordinary maintenance will no longer suffice, and if roads are to be fully restored, rehabilitation or even reconstruction work is necessary, at a lifecycle cost three to seven times higher than that of preventive maintenance strategies.
Rigid pavements have a relatively long service life if they are properly designed, constructed and maintained. These pavements can serve up to its design service life and even beyond if timely repairs and rehabilitation are undertaken. All types of pavements deteriorate with time, however, the rate of deterioration is comparatively much slower in rigid pavements than in flexible pavements.
Rigid Pavement Maintenance is more than just a collective set of specific pavement maintenance techniques. It is a way of thinking and the guiding force behind an agency's financial planning and proper asset management. Pavement management must be tailored to each road agency's system to meet the need of various pavement distresses in the most cost-effective manner. This involves using a variety of treatments and pavement repairs to extend the rigid road pavement's life.
Most of the Pavement Designs involve two or more performance periods. A pavement is constructed at an initial serviceability level and is rehabilitated to an acceptable level at some time during its design life. This process of rehabilitation may be repeated several times depending on the condition of the existing rigid pavement, from time to time.
Figure 4: Faulting/SteppingRoad Management System needs to be established on a computer system platform on client server at the headquarters of Ministry of Road Transport & Highways (MoRTH). Software for GIS, HDM, Image Processing Software, Terrain Modeling, Software and AutoCAD may be required for the proposed planning model. A resourceful consortium of consultants having expertise in all these areas could be required to develop the system on a turnkey basis and hand it over to the client, after customizing and operationalizing it.
The author has exhibited his field experience in maintenance of rigid pavement through photographs and figures captured at project sites as case studies. This paper will benefit the practicing engineers in rigid pavement construction in projects in particular, and others in general.
Distresses of Rigid Pavement
Potholes, Scaling, Blow-ups, mud pumping, spalling, Loss of Sealant, Cracking (longitudinal, transverse, reflection, sympathetic), corrugation, joint deficiencies and faulting are the distresses occurring in rigid pavements, however, the considered distresses were Cracking, Potholes, joint deficiencies and faulting in the data collection procedures)
Pavement Condition Index (PCI)
- PCI is a numerical indicator of overall pavement condition
- It takes into account the roughness and distresses of pavement
- As trigger to plan maintenance and rehabilitation activities
- Identification of immediate pavement maintenance and rehabilitation needs
- Ranking of road for maintenance and rehabilitation
- Developing road maintenance for short-and long-term plans, and budget
- Policy for minimum service level for various roads' Pavement Main- tenance System (PMS).
Maintenance Management Systems (MMS)
MMS is a technique or operational methodology for managing or directing and controlling the judicious use of maintenance resources. Effective MMS is doing the correct thing at the correct time and in the correct place. For modern Roads & Highways, to be operated efficiently and effectively for the benefit of all users, it is required to meet customer's defined requirements. Road drainage performance plays a vital role in ensuring the pavement performance.
Pavement Management Systems (PMS)
PMS constitutes the following aspects:
- Pavement Condition Data
- Maintenance Standards
- Economic Analysis
- Programming
- Control of Works and Feedback.
- Budgetary Analysis
Maintenance needs are assessed every year as part of planning and considering the following factors:
- Traffic
- Survey
- Visual rating
- Roughness measurements
- Axle Load Survey
- Concrete pavement restoration (CPR)
- Crack sealing
- Cross crack stitching (Longitudinal and Transverse crack)
- Diamond grinding for rectification of pavement faulting
- Dowel bar retrofit
- Isolated,partial or full depth concrete repair
- Joint resealing
- Repair of edge spall and corner
- Breaks of slabs
- Slab lifting or slab jacking or under-sealing
- Ultra-thin white topping
- Evaluate Structural Adequacy
- Causative factors that cause distress
- Select the course of maintenance
- Patching
- Sealing
- Re-surfacing
- Re-texturing
- Diamond grinding
The emerging repair materials for the maintenance of rigid pavements are high strength and high performance concrete using fly ash and silica fume, synthetic resins, magnesium phosphate cement, magnesium oxy-chloride cement, silicon sealant, poly-urethane sealant, sulphur and sand mortars.
Strategic Repair and Rehabilitation Techniques
It has been often said that there is a tendency to "build pavements and forget them." Reconstruction is a form of rehabilitation for highway rigid pavements as the existing pavements continue to deteriorate and demand increased maintenance costs. Advances have been made in recent years in the development and use of quick setting and rapidly hardening materials for repair and rehabilitation.
Highway Design and Maintenance (HDM) Standards
The World Bank has developed the Highway Design and Maintenance standards model and its version-4 (HDM-4) is presently in use. HDM-4 has been calibrated for Indian deterioration and user cost models and customized for the chosen computer system platform which will bring the planning process to state-of-the-art level.
Road network maps can be digested using Survey of India (SOI) base maps and the mapping data can be held in the Geographic Information System (GIS) format in a cartographic database for road condition and road inventory surveys. The entire road management system needs to be established on a computer system platform on client server model at the headquarters of Ministry of Road Transport & Highways (MORTH). The consortium of consultants could be required to develop the system on a turnkey basis, and hand it over to Ministry of Road Transport & Highways (MORTH), and National Rural Roads Developments Agency (NRRDA).
Figure 8: Joint and Crack Filling Prior to the Application of a New Surface Treatment- The traffic on roads is likely to increase enormously in future
- To meet the demand optimally and to ensure rapid economic progress of the country, it is essential to develop and establish an efficient road and highway planning and management system
- Effort is also required to integrate various systems related to highway management carried out in India and abroad
- Maintenance-by-Contract of Highways should be privatized or as a part of construction contract to reduce burden on the exchequer
- We should follow-up strict construction supervision and stringent quality control measures and must protect our investment with minimal maintenance costs
- Proper rigid pavement design, regular inspection and maintenance of drainage system is of utmost importance
- The roads and highways maintenance strategies would reduce losses caused due to bad condition of roads.
- After having the pavement assessment and evaluation done, strategic maintenance and rehabilitation should be considered, including full-depth patching, joint sealing and sub-surface drainage, repairing of cracks, repairing of spalled joints, grout jacking of slabs, reconstruction, etc
- All patches should preferably be full depths; misaligned dowel bars create high load transfer stresses at the joints
- "D" cracking (D-shape) of slabs is caused by poor quality aggregates that absorb water and swell on freezing near joints and the slab cracks, causing severe and rapid loss of pavement serviceability
- Pumping causes significant loss of pavement serviceability and could be reduced by providing proper sub-drainage
- The chloride and sulphate contents in the concrete required for rehabilitation and maintenance should not be more than 0.15% and 4.0% by weight of cement, respectively.
- It is preferable to use high performance concrete or Portland slag cement concrete for maintenance of concrete roads, especially in coastal areas
- At present, it is assumed that strategic operational maintenance costs of rigid pavements are approximately equivalent to the repair costs for flexible pavements. Currently, there is no sufficient data available in the cost accounting system to determine if there is any difference. It is recommended that selected pavement types for high speed corridor segments be identified and monitored for operational maintenance costs
- Repair and maintenance of rigid pavements in heavy traffic areas is of concern to motorists who have to use high-speed corridors during periodic maintenance operations
- An economic formula should be used to compare the cost of rigid pavement options on an annual maintenance costs per kilometer basis for corridors.
- The bituminous resources are dwindling day by day in the country vis-à-vis Portland cement, and rigid pavement is one alternative and economical solution for today's transportation system
- The principle to "think globally and act locally" is to be ensured for rigid pavement construction at all costs
- Portland cement is a man-made material and its supply is in abundance for construction of rigid pavements apart from its use in building construction
- Experience has shown over the years that rigid pavements should be well designed, fully mechanized, of quality construction and contractually well maintained
- The strong message is "to do things right first time and every time" in the rigid pavement construction industry otherwise one gets little or no chance to correct the mistakes made during the process of construction they will be corrected at a great expense
- Above all, the scope of rigid pavements is much more promising than other types of pavements including flexible pavements due to their techno- economic benefits.
- There is a need for guidelines on the strategic maintenance of flexible pavement, which should be easy to use, understandable and cost-effective, and provide uniformity in evaluation process and management methodology. Good information about road conditions is an essential pre-requisite for sound decision making for road maintenance, and type of treatment that is subsequently applied.
- A greater emphasis is also likely to be placed on improving communication with road users to provide them with up-to-date and reliable advice about the condition of the road, The wide use of roads and their impact upon those they serve, offer great challenges to Road Maintenance Engineers to ensure that the assets for whose upkeep they are responsible are maintained for the benefit and convenience of all the road users.
- Most important aspects of the future challenges are: Where does the future of Pavement Management Systems go from here? How can we upgrade and improve the technology of the Pavement Management System? How can we improve the Pavement Management System itself?
References
- US Department of Transportation, Federal Highway Administration." Distress Identification Manual." Publication No. FHWA-RD-03-031 June, 2003.
- Indian Road Congress. "Tentative Guidelines for Repair of Concrete Pavements Using Synthetic Resin." IRC: 77-1979, New Delhi, 1980.
- American Concrete Pavement Association. "The Concrete Pavement Restoration Guide." TB020P, Skokie, Illinois USA.
- IRC: SP: 83-2008 – Guidelines for Maintenance, Repairs & Rehabilitation of Concrete Pavements, Indian Roads Congress, New Delhi (Dr. S. S. Seehra, Ex-Member- Secretary- Rigid Pavement Committee (H-3) , 2007, was associated actively in the preparation of these guidelines by the Rigid Pavements Committee of IRC ).
- Dr. S.S. Seehra "Rigid Pavement Repair and Maintenance Strategies for Roads & Highways" Published in the Journal of New Building Materials & Construction World (NBM & CW) Vol. 18, Issue-10 April, 2013, New Delhi, India
- Dr. S. S. Seehra "Development of a New Technique for Improving the Surface Texture of Cement Concrete Pavements", published in International Symposium on "Innovative World of Concrete" Bangalore, held from 30th Aug. to 3rd Sept. 1993.
- Dr. Baffour Kwaku Akoto & Eufemio E. Niles "Repair & Restoration of Concrete Pavements "Journal of Indian Roads Congress, Volume 68-1, 2007, New Delhi, India.
