1.1 Background of the Study
Adequate planning and design of good pavement is germane to the development of a nation. This is because properly constructed road network enhances economic growth of any nation by encouraging efficient movement of goods and services. Thus, good road network reduces haulage vehicle accidents by minimizing human and material losses (Akintorinwa, Ojo, & Olorunfemi, 2010). In the developing countries such as Nigeria, road network is the most developed transport mode and the vastest in usage (Okigbo, 2012). Roads represent the major areas of investment in transportation according to Oguara (Oguara, 2010) and are also the dominant travel mode accounting for over 90% of passenger and goods transport in Ghana.
A good road network in the rural areas is one of the key components of Millennium Development Goals, stated Collins and Hart (1992), because it promotes access to economic and social services, like increase in agricultural productivity, employment opportunities and poverty alleviation.
Regrettably, despite huge financial resources being sunk into the transportation sector, its roads have continued to pose serious dangers to motorist due to its deplorable state with attendant economic losses to the populace especially as a result of loss in man hours arising from delays on several bad portions of the road. Despite its vast potentials for growth and development, the roads have not been satisfactory in terms of its performance (Adewumi, 2008). Most of the problems leading to the deplorable state of Ghanaian roads are directly or indirectly related to the poor planning of pavement design but an adequate knowledge of the effect of pavement failure on our roads will help in reducing the menace arising therefrom.
There are two major types of pavement – the flexible pavements and the rigid pavement. Both pavement types contribute in making highway transportation possible. A highway pavement is a structure consisting of superimposed layers of selected and processed material whose function is to distribute the applied vehicle loads to the subgrade (Saurabh, Joshi, & Goliya, 2013). Only rigid pavement will be considered in this study.
Rigid pavements also referred to as concrete roads, offer many benefits in the long-term. Economically, they are often the most favourable option to flexible pavements when life cycle costs are taken into account. This is due to the fact that concrete requires minimal maintenance and results in less disruption to road users when properly designed and built using durable materials and methods. Concrete pavements have been used for local roads, streets, highways, airport runways, parking areas, industrial structures, and other types of infrastructure. With decades of construction and use of rigid pavements, it has become clear that in comparison to flexible pavements (asphalt-paved), sustainability of the environment is favourably impacted by their longer service life. Bryan Perrie, a South African professional pavement engineer stated “it has been found that the concrete roads built in the past in South Africa are lasting considerably longer than was originally anticipated” (Halwindi, 1999). Concrete surfaces also have a higher reflectiveness off its surface, this allows for improved visibility at night and reduced lighting on the road (Rens, 2009). We may also take note of the reduction in traffic delays caused by concrete pavement construction which can be reopened even after a couple of hours as opposed to flexible pavements construction, which in turn cuts back on fuel consumption and exhaust gas emissions. Concrete roads are designed to resist flexural loading from traffic loading and crack control from a host of processes such as drying shrinkage, curling and warping (ACPA, 1992; Delatte, 2008). Flexural strength of concrete can be higher than tensile strength but will be lower in homogenous materials. Higher flexural strength will result from the concrete under loading having stronger materials at their edges, since only extreme fibres are the points of largest stress which makes it deform at higher stress. Concrete pavements distribute stress over a large area; therefore base layers undergo less pressure from axle loading.
Gupta and Gupta (2004) in concrete Technology gave the importance of Rigid pavement as consist of a relatively rich mixture of Portland cement (0.14m3, sand (0.29m3 ) and course aggregate (0.57) land as a single course. Rigid pavement is a pavement that possesses enough flexural strength or flexural rigid. Also, Gupta and Gupta were of view that stresses are not transferred from top to the lower layer as in the case of flexible pavement.
The design of rigid pavement is based on providing a structural cement concrete slab of sufficient strength to resist the load from traffic. It has a rigidity to distribute the load over a relativity wide area of soil and a minor variation in subgrade strength, has little or no influence on the structural capacity of a rigid pavement. Highway engineering construction has Highway Research board system that mostly regarded in the determination of pavement thickness and materials for base course gives yearly report on highway.
Afser (2012) asserted that flexural strength of concrete is the major factor in rigid pavement design, not the strength of the subgrade. He further emphasized that concrete slab of rigid pavement, bridges over the localized failure and areas of inadequate support from subgrade in the course of deflection beneath it, because of concrete slab action. Kadiyali and Lai (2011) in their principles, and practice of highway Engineering provided an overview of rigid pavement structure, being composed of hydraulic cement concrete surface course, underlying base and subbase course and provides the majority of strength. The subbase and the base layers are in the order of magnitude less stiff than the concrete surface but still contributes importantly to pavement drainage and provide a working platform for construction equipment.
H.R.B (1987) on the final report of committee on maintenance of concrete pavement compared the performance of rigid to flexible pavement in the swampy soil as it contains sufficient rigidity and has high modulus of elasticity cable of bridging over any localized subgrade failure or areas of inadequate support. Rigid pavement, with a relatively small thickness, distributes wheel load upon the subgrade, and bridges minor inequalities in subgrade support, by virtue of flexural strength and load transfer capacity in shear, Maclean et al (1979). The reaction of concrete pavement slab to environment and loading depends of properties of the concrete of which they are cast and those of underlying subgrade and base course.
Factors that lead to pavement failure are numerous and it is pertinent to first identify such factors and then classify them for effective understanding and management of the problems for developmental growth of a nation. It is said that pavement failure arises from functional failures (Woods & Adcox, Spring 2002)and the assignment of categories makes the understanding of pavement somewhat easier. Proper identification of pavement will ultimately enable the relevant agencies to appreciate the causes of pavement failure with a view to providing remedial measures to mitigate the failure. Maintenance plays an essential and integral part in the life of a pavement. 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 needs to cater to 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 pavement life. The 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 point of time during its design life. This process of rehabilitation may be repeated several times depending on the condition of the existing pavement deteriorating from time to time
1.2 Statement of the Problem
The rapid growth in 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 life cycle cost three to seven times higher than that of preventive maintenance strategies.
Rigid pavement has shown great performance in urban area and interstate highway settings for many years because of its low maintenance requirements and capability for long service life. However, rapidly increasing heavy traffic accelerates pavement deterioration and increases the need for more maintenance than in the past. If proper maintenance is not employed at low levels of deterioration, in a timely manner, acute degradation of pavement serviceability will occur and major repair costs may be needed.
Rigid pavements have a relatively long service life if these are properly designed, constructed, and maintained. Rigid pavements can serve up to its design service life and even beyond if timely repairs and maintenance are undertaken. All types of pavements deteriorate with time. Rate of deterioration of rigid pavement is comparatively much slower than other pavements. Hence, the study focuses on the deplorable state of roads and the need for proper maintenance on rigid pavement.
1.3 Objectives of the Study
The study sought to assess the deplorable state of roads and the need for proper maintenance on rigid pavement. Specifically, the study sought to;
1. ascertain the causes and types of pavement deterioration.
2. examine the maintenance strategies of rigid pavement.
3. examine the concept and different types of pavement maintenance management system.
1.4 Research Questions
1. What are the causes and types of pavement deterioration?
2. What are the maintenance strategies of rigid pavement?
3. What is the concept and different types of pavement maintenance management system?
1.5 Significance of the Study
This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.6 Scope/Limitations of the Study
This study is on the deplorable state of roads, the need for proper maintenance on rigid pavement.
Limitations of study
1. Financial constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).
2. Time constraint: The researcher will simultaneously engage in this study with other academic work. This consequently will cut down on the time devoted for the research work.
1.7 Definition of Terms
Deplorable:Deplorable is an adjective used to describe something extremely bad or unfortunate
Maintenance:The process of preserving a condition or situation or the state of being preserved.
Road maintenance: Road Maintenance involves remedying defects such as potholes that occur in the carriageway from time to time (corrective maintenance) and providing treatments such as crack sealing which will slow the rate of deterioration (preventative maintenance). Maintenance actions help to slow the rate of deterioration by identifying and addressing specific pavement deficiencies that contribute to overall deterioration.
Pavement: Pavement is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway.
Rigid Pavement:A rigid pavement is constructed from cement concrete or reinforced concrete slabs. The design of rigid pavement is based on providing a structural cement concrete slab of sufficient strength to resists the loads from traffic.