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Quality Control in Construction Projects
Quality control (QC) is a process through which an organization
intends to ensure that product quality is maintained or improved. Quality
control requires the organization to create an environment in which both
management and employees aim for perfection. This is done by training
personnel, creating benchmarks for product quality and testing products to
check for significant variations.
A main aspect of quality control is the establishing of
well-defined controls to standardize both production and reactions to quality
issues. Limiting scope of error by specifying which production activities are
to be completed by which personnel reduces the chance that employees will be
involved in tasks for which they do not have sufficient training.
Quality control (QC) is a procedure or set of procedures prepared
to ensure that a manufactured product or performed service adheres to a defined
set of quality criteria or meets the requirements of the client or customer. QC
is similar to, but not identical with, quality assurance (QA). QA refers to the
confirmation that specified requirements have been met by a product or service,
whereas QC refers to the actual inspection of these elements.
Definition of Quality Control
Juran (1999), defines quality control as a universal managerial
process for conducting operation so as to provide stability to prevent adverse
change and to ”maintain the status quo.” To maintain stability, the quality
control process evaluates actual performance, compares actual performance to
goals and takes action on the difference.
Chung (1999), defines quality control as referring to the
activities that are carried out on the production line to prevent or eliminate
causes of unsatisfactory performance. In the manufacturing industry, including
production of ready-mixed concrete and fabrication of precast units, the major
functions of quality control are control of incoming materials, monitoring of
the production process, and testing of the finished product.
From the foregoing, quality control can be defined as the set of
measures and procedures to follow in order to ensure that the quality of a
product is maintained and improved against a set of benchmarks and that any
errors encountered are either eliminated or reduced. The focus of quality
control is to ensure that the product and product manufacturing are not only
consistent but also in line with customer requirements.
Quality Control Procedure
The procedure for meeting
the industrial goal is termed quality ‘Control,’ just as the procedure for
measuring production and cost goals are termed, respectively, production
‘Control’ and cost ‘Control.’ There are normally four steps in such control:
1-
Setting Standards. Determining the
required cost–quality, performance–quality, safety–quality, and
reliability–quality standards for the products.
2- Appraising Conformance. Comparing
the conformance of the manufactured product, or the offered service to the
standards.
3-
Acting When Necessary. Correction
problems and their causes throughout the full range of those marketing, design,
engineering, production, and maintenance factors that influence user
satisfaction.
4-
Planning of Improvements. Developing
a continuing effort to improve the cost, performance, safety, and reliability
standards.
Control Steps
Gryna (2001) refers to quality control as the process employed to
consistently meet standards. The control process involves observing actual
performances, comparing it with some standards, and then taking action if
observed performance is significantly different from the standard.
Control involves a universal sequence of steps as follows:
1-
Choose the control subject, that is,
choose what we intend to regulate.
2-
Establish measurement.
3-
Establish standard of performance,
product goal, and process goals.
4-
Measure actual performance.
5-
Compare actual measured performance
against standards.
6-
Take action on the difference.
Quality Control Techniques
There are a variety of methods, tools, and techniques that can be
applied for quality control and the improvement process. These are used to
create an idea, engender planning, analyze the cause, analyze the process,
foster evaluation, and create a wide variety of situations for continuous
quality improvement. These tools can also be used during various stages of a
construction project. The following are the most commonly used quality control
tools for a variety of applications to improve the quality process:
1-
Cause-and-effect diagram
2-
Check sheet
3-
Control chart
4-
Data collection
5-
Flow chart
6-
Histogram
7-
Pareto analysis
8-
Pie chart
9-
Run chart
10- Scatter diagram
Quality Control vs Quality Assurance
According to the AmericanSociety for Quality (ASQ), quality assurance is defined as a “planned and
systematic process of activities implemented in a quality system so that the
quality requirements and goals for a service can be fulfilled”. The same
website explains quality control as an “observation technique that comes with
certain activities that are there to fulfill requirements for quality”.
So, there is a difference between these two aspects of quality management.
Quality assurance ensures that the approaches, techniques, methods
and processes that are designed for the projects are performed correctly, while
quality control focuses on the actual quality of deliverables that are being
produced under these tested methods, processes, approaches, and techniques.
The main goal of QA is to set procedures and processes in place
that will minimize risk and prevent any predictable defects from happening.
While the main goal of QC is to inspect the quality of everything concrete
that’s done under these processes and determine if the work is meeting the
quality standards of the project. QC is often used to accept or reject
solutions.
Importance of Quality Control in Construction
In order to boost owner satisfaction during a construction project,
the project must meet the expected quality, which can be ensured through
quality assurance and quality control activities. The quality control process
confirms that the project outcome meets the owner’s standards. The quality
assurance process checks the quality plan and quality control process to
confirm that quality standards are implemented on the project site.
Understanding project requirements and standards is essential to improve the quality
construction of the project. This is usually done by a team outside of the
project, and the goal of this practice is to maintain quality standards,
eliminate practices that are not appropriate and share best practices for
quality assurance in the organization and with the project construction team.
The project quality plan should be part of the project construction
management plan. The quality control plan defines how quality should be handled
throughout the duration of the project.
Omission the quality control procedures of a project incurs
additional expenses and project delays. Having to rework increases the
maintenance and opportunity costs. Structural elements that are not built
according to quality assurance standards have the potential to collapse at any
time, which could lead to injuries and death.
Role of Quality Control in Construction
Quality can be defined as the degree at which product is probably
to meet the required specification and limits given by the construction agency.
This control ensures that the work done must be of required quality
and durability. This can be carried out by conducting inspection of work from the
material supplier up to the finished production. Main
items of control before and during construction are verifications of soil
characteristics, drawings and designs, structural safety, durability, checking
the quality of materials, specifications, testing of materials and inspection
of equipment.
The field of quality control is multidirectional like testing of
materials to be used, field and laboratory tests on mixed materials,
appropriate knowledge of methods/techniques to executive staff/contractor,
Precautions to be taken and various periodic tests. Firstly, materials to be used in works should be conforming to
specifications required. The important step towards improving the quality of
work is to ensure that all materials and fittings used in the work are conform
to the standards laid down in the contract and specifications mentioned
therein. As far as possible materials approved should be used in works. If
standards do not exist for a particular material, the same should be purchased
from some standard manufacturer and got tested from approved test labs.
Implementation of Quality Control in Construction
Quality control can be maintained by the utilization of right
engineering practice, professional attitudes, good construction practices and
quality. In the case of engineering structures. It may be understood as a
function of making men, materials, machines and methods operate at the
standards calculated to ensure that the end result of the construction conforms
to the prescribed specifications as well as meets the owner/users requirement.
Quality control is a management activity used to the construction
processes to set purposes. Purpose in this case being achievement of prescribed
standard of performance and cost. To achieve optimum quality at minimum cost,
we have to take into account all the factors that help to build quality into a
product or service.
In the construction sector where main part of works are executed by
the contractor the responsibility of quality control is in the contractor and
he is responsible to the designer and the owner for this.
The main problems facing the development of construction projects are the technological progress of their creation, the improvement of their quality, reliability and factory finishing. These problems can be solved by developing and applying efficient and continuous quality control at each stage of production and by testing products and structures using the latest tools and machines. In the now day competitive market of construction industry if a contractor has to survive, he should be able to meet the quality requirement of the owner/user and satisfy his needs as well as meet the conformance standards. The various process involved to be able to meet the above requirement should be cost effective.
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