1.1 Introduction
Premature pavement failures typically occur within the first
half of a rigid pavement’s design life and within 5 years after
completion of the project for flexible pavements. Premature pavement
failures can be attributed to any number of factors or combination
of those factors, including inadequate structural design or incorrectly
addressing existing structural deficiencies, inadequate consideration
of design compatibility with the abutting pavement, poor quality
or non-uniform materials, inadequate surface preparation, or poor
construction. Despite advancements in pavement technology in past
decades, premature failures and chronic pavement distresses continue
to occur. Experience has shown that the majority of premature pavement
failures in Texas are related to material and construction deficiencies.
Material deficiencies can be related to inadequate assessment of
existing materials and what measures are needed to enhance their
attributes for better performance. Although improvements have been
made to construction specifications, equipment, and construction
processes, poor quality construction or use of substandard materials
can occur due to a number of complex and sometimes competing variables,
such as:
- reduced inspection staffing,
- employee turnover,
- fluctuations in levels of experienced inspectors, project managers and engineers,
- incompatibilities between new admixtures and construction materials,
- implementation of new technologies, construction methods, and best practices,
- environmental constraints and recycled materials,
- issues unforeseen during design and construction phases.
To prevent or reduce the probability of premature pavement
distress and poor long term pavement performance, the root causes
of these problems have to be identified. It is a challenging task
to determine the causes of pavement distress. A pavement distress
investigation involves a thorough review and analysis of existing
construction quality control records and tests, and nondestructive testing
such as ground penetrating radar (GPR), falling weight deflectometer
(FWD), and dynamic cone penetration testing (DCP). These are essential
to identify problematic areas and probable causes. Additional field
testing, such as portable FWD, dirt seismic pavement analyzer (DSPA), coring,
trenching, and laboratory testing, may be conducted to confirm the
initial hypothesis. The outcomes from investigations can be used
to validate or modify the existing design plan and to resolve the
disputes involving construction claims or change orders.