QUALITY CONTROL OF CONCRETE

Quality control implies that the assigned work is done according to the specifications agreed in the contract. Major civil engineering works such as multistoreyed buildings, dams, harbours, etc., have to be constructed with utmost care as they have to last and be used for decades. Specifications of work should be framed based on cost or standard processors so that they serve effectively as a guide to complete the work with high quality. The specifications are as important as the design of the project.

To make a quality concrete construction at a site, fieldwork has to be organized with the three divisions with mutual coordination, viz., the engineering division, the manufacturing division and the placing division. The engineering division looks after all forms, reinforcements details and installation of all embedded parts. The manufacturing division takes care of the control of materials, batching and mixing of concrete. The placing division takes care of placing, curing and other subsequent works.

The whole aim is to produce inexpensive high-quality concrete. The general requirements to produce high-quality concrete, i.e., densest, more workable and high strength, are as follows:

1. Air bubble should be completely removed from the concrete.
2. Compaction of concrete should be such that a minimum void is present.
3. Adequate curing for 28 days has to be effected.

Resources such as supervisors, engineers, etc., who are involved in the production of high-quality concrete should be aware of all the factors affecting good-quality concrete. Accordingly, the execution of quality control of concrete should be carried out at every stage. Carefully constructed high-quality concrete work has the following advantages:

1. The possibility of failure is minimized.
2. Lower cost of construction with long life.
3. Low-maintenance cost.
4. Possibility of using low-grade materials for some other purposes.

In summary, to obtain high-quality concrete all suitable precautions must be taken to ensure proper inspection of the ingredients, proper batching and mixing, proper transportation and careful placing, adequate curing and careful renewal of formwork and necessary finishing.