Paper and Presentation by Liangliang Chen and Dan Zollinger from ASCP 2nd Conference 2013
This paper addresses key issues regarding important factors affecting the sustainability and long-term performance of PCC pavement structures. Key distress types and their associated features are discussed in terms of their effect on performance and sustainability in terms of specific pavement components. Relevant material properties are also identified and discussed as to how they are represented in laboratory and field testing. A process to manage inspection resources is described and illustrated.
Pavement sustainability can and frequently does have a broad range of definitions that may reflect conflicting objectives and purposes but in the context of this paper, pertains exclusively to the quality of the structural-related performance of a pavement structure over given service life.
Furthermore, the definition of sustainability referred to in this document will be tied to perpetual pavement longevity as founded in the life cycle assessment (LCA) and its capability to be sustained in its original configuration over a given period of time (1). Inherent to such a discussion is the optimization of an acceptable level of pavement structural condition over time and the minimization of the impact of current rehabilitation decisions to limit the capability of future generation to achieve cost-effective repair alternatives.
Achieving sustainable pavement performance first of all involves gaining an understanding of pavement behavior and how that behavior is affected by key pavement subsystems and their association with cycles of deterioration, which if allowed to become advanced enough, will affect the functional and structural capacity of a pavement and limit its overall use. It also involves the understanding of the performance-related functionality or the utility of common material tests used for inspection and specification purposes to represent performance and to serve as an aid in the assessment of selected design, material, construction, or maintenance combinations to provide sustainable performance.
Discussion in this document will address how the assurance of a a sustainable level of performance can often be governed by the success of two key activities:
- Performance monitoring, and
- Construction inspection
This is a key issue with regard to sustainability and to make the outcome of these two components beneficial over a long period of time, it is important that key activities for each component be identified and elaborated in order to better insure the result of the application and optimal benefit of each. The first of these activities will be elaborated later but it does involve a very important focus pertaining to the maintenance of a pavement structure at a high level of service and minimizing the cost to do so over a given period to time. The second activity has traditionally been high on the list of the responsibilities commonly undertaken by the project owner during construction to positively affect the outcome of the overall construction effort, as it should be.
One of the key aspects any inspection program is to ensure quality in the constructed product and to prevent, to the extent possible, the development of unexpected, premature distress in the constructed pavement and infrastructure. Premature distress is often a function of and dependent upon prevailing weather conditions which often affects the quality built into the constructed product. One purpose of inspection is to minimize the effects of circumstances involving methods of construction, materials, and weather that can lead to premature failure; the minimization is facilitated by tests and checks conducted by the inspector to provide an indication of less than acceptable conditions when they exist. Most tests selected for use in construction inspection and specification yield useful values of measured properties or parameters that reflect the quality of the constructed product and in some cases the level of expected service over the design life. The better a test method is able to detect a key property or a characteristic the better is its utility to indicate performance. Not all tests address or involve the same amount of variability or risk in determining unacceptable results and as a consequence, do not or would not share the same level of testing liability due to perhaps a higher confidence level in measuring a meaningful test parameter and/or achieving an acceptable level of testing precision.