United States Department of Transportation
About
i
Quality control and quality assurance of hot mix asphalt construction in Delaware.
-
2006-07-01
[PDF-1.77 MB]
Details:
-
Creators:
-
Corporate Contributors:
-
Subject/TRT Terms:
-
Resource Type:
-
Geographical Coverage:
-
Corporate Publisher:
-
Abstract:Since the mid 60’s the Federal Highway Administration began to encourage
Departments of Transportation and Contractors toward the use of quality control and
quality assurance (QA/QC) specifications, which are statistically based.
For example, a QA specification has become an important component in
organization commitment to overall quality management. This consists of several
activities including: process control, acceptance, and sometimes independent assurance of
product (Buttlar and Harrell, 1998). These specifications must be designed to reward
good quality, and penalize poor quality.
The QA specification, also called as the QA/QC specification, is a combination of
end-result specifications and materials and methods specifications. The highway agency
is responsible for the acceptance of the product that is produced by the contractor
following or implementing quality control in order to produce a product that meets the
specifications provided by the highway agency.
QA specifications typically are statistically based specifications that use methods
such as random sampling in which the properties of the desired products or constructions
are described by appropriate statistical parameters, and lot by lot testing. These methods
would help the contractor know whether or not the operations are producing the
acceptable product.
Specifications for the construction of asphalt pavements can be classified into
propriety specifications, method – related specifications (MRS), end – result
specifications (ERS), performance – related specifications (PRS) or combination of these
specifications.
• Propriety Specification
This type of specification refers to some specific product or its equivalent in its
clauses; therefore, it limits the competition and often results in a cost increase. Since the
buyer has to accept the product as a “black box”, the buyer’s risk is much higher than in
the other three types of specifications
• Method Specification
This type of specification outlines a specific material selection and construction
operation process to be followed by the contractor in providing a product. Since there is
no explicit product specified, this type of specification allows competition among various
suppliers and contractors; but, because the buyer sets the requirements for materials and
methods, the owner has to bear the responsibility of the performance.
• End-Result Specification
The final characteristics of the product are stipulated in the end-result specification
and the contractor is given considerable freedom in achieving those characteristics. It
may specify a limit or range for any given material and/or construction characteristic. The
risk for the contractor or agency depends on how the acceptance limits and processes are
specified.
• Performance Related Specification (PRS)
This type of specification holds the contractor responsible for the finished product’s
performance; thus, the contractor assumes considerable risk for the performance of the
finished product. This type of specification is often used in conjunction with some type of
warranty. The challenge here is to use “true” performance indicators, which may not be
available for all materials and processes.
Statistical acceptance specifications tend to provide a more defensible approach to
specifying HMA construction than the previously used methods of specification (Muench
and Mahoney, 2001).
-
Format:
-
Collection(s):
-
Main Document Checksum:
-
File Type:
Supporting Files
-
No Additional Files
More +
