Abstract:
Proper compaction plays a vital role in maintaining the quality of asphalt pavement works. As
a quality control (QC) and quality acceptance (QA) parameter, the degree of compaction
expressed as a percentage ratio between field density and the reference density is employed in
the pavement industry. Currently, Marshall density, maximum density and control strip
density are used to establish the reference density and formulate the degree of compaction.
However, for decades, Marshall laboratory density has been the mainstream practice to
specify the reference density in Sri Lanka. This study focuses on developing a systematic
approach called the "Standard density method" to establish the reference density. The
standard density is determined as the mean value of densities of Marshall test specimens from
morning and evening operations for a specified number of days after the commencement of
construction. The experiments were designed to evaluate the feasibility of the concept of
standard density by comparing current practices with the proposed method. Field core density
and Marshall laboratory density measurements were collected from various road projects, and
compaction performances were evaluated. A graphical comparison, a statistical test method (t
-test) and validation tests were conducted to analyze the compaction performance and
acceptance of the proposed method. The findings showed that standard reference density
could be used as the most effective QC / QA testing parameter for roads that use the same
asphalt mixture design, batching plant, laying and compaction procedures. Moreover,
statistics revealed a significant relationship between the level of compaction results in both
current and proposed methods in major projects. Furthermore, the results showed that the
standard density method is very sensitive to the variations in asphalt manufacturing, placing,
laying and compaction procedures.
