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.