The term quality control in civil engineering parlance is used to mean that the work is done according to the specification provided in a contract document.
The concrete structures like multi-storeyed buildings, skyscrapers or dams are built to last many decades and hence the quality control of concrete during the construction of such important structures is a must and it has to be attended to with intelligent and scientific approach. The specifications of work should be framed with extreme care so as to serve effectively as a guide to get the job done well. As a matter of fact, the specifications are as important as the design of the project.
The concrete as such is a heterogeneous material and hence it would assume a wide range of properties, if produced without exercising any control. For preparing a high quality concrete, the field organization may broadly be divided into the following three divisions:
(1) The engineering division which a provides lines and grades and makes the initial inspection of all forms, reinforcement and installation of all embedded parts.
(2) The manufacturing division which exercises control over concrete materials, batching and mixing.
(3) The placing division which is concerned with the control of concrete placing and of related operations prior and subsequent thereto.
The concrete produced at site should be strongest, densest, most workable and most economical for the job for which it is prepared. The amount of cement should be low and that of aggregates should be high. The most economical concrete with the highest possible density is obtained by observing the economical general required.
(1) The air bubbles should be eliminated from the body of the concrete.
(2) The cement particles should be of the smallest size.
(3) The concrete would be compacted fully so as to remove voids.
(4) The concrete should be cured sufficiently and adequately, say for 28 days.
(5) The cubical particles of the aggregates should be used so that good interlocking is gai
(1) It helps in improved utilization of scarce resources and in extended utilization of low-grade materials.
(2) It helps to minimize failures.
(3) It results into lower costs of construction as higher stresses can be assumed.
(4) The structure becomes durable with lower costs of maintenance.
It should be remembered that the road to achieve quality is not easy and hence, if a uniform product is required, all the ingredients and procedures which make up this conglomerate must also be uniform within permissible limits, no once in a while, but everyday until the structure is completed. Hence all suitable precautions must be taken to insure proper inspection of the ingredients, batching, mixing, transporting and placing and if found necessary, the standards applicable to all these process must be improved so as to deliver to the owner a project of acceptable quality.