Inspection and Quality Control in construction Management

This a chapter of construction planning and Management

1. Inspection and Quality Control

2. Need for Inspection and Quality Control Inspection is the art of checking materials, processes and finished products and comparing the same with laid down standards to ensure that these are according to specification During construction work, inspection involves constant watch over different operations, so that any defect, if observed, is got rectified during course of construction and the work is completed according to laid down specifications Objects: The inspection and quality control is essentially required to: Improve the quality of the work Increase the life span, durability and stability of the structure Put all available resources into economical output Reduce un-necessary repairs and maintenance Maintain the reputation of the enterprise.

3. Function of Inspection Department Material Inspection: This is done to ensure that the materials being procured are according to laid down specifications and as per terms and conditions of supply order Process Inspection: This is done to ensure that the operations are being carried out correctly and systematically, so that the finished job is in accordance with laid down standards and the materials used in the construction are as per standard specifications and free from defects Equipment Inspection: This is done in order to ensure that the equipment being procured is as per requirement of the project and exactly according to the terms and conditions of supply order. Finished Job Inspection: After the job is completed it is inspected thoroughly so that the same is in accordance with laid down standards

4. Principles of Inspection Control over Materials and Equipment: The Quality control of materials and equipments must be ensured properly. It can be done by inspection of the materials and equipment time to time. There are two ways of inspection, i.e. Inspection at source of supply Inspection at construction site a. Inspection at source of supply: The raw materials required for the project should be inspected at source of supply to avoid low standard material coming to the construction site. Similarly the equipment to be purchased or hired should be inspected at the place of suppliers to avoid unnecessary botheration and expenses for transporting back the equipment if rejected. b. Inspection at construction site: The second method of inspection of materials and equipment required for work is the inspection at the construction site. This ensures the supply of proper quality of materials and equipment. 2. Planning of Inspection Operations: the planning of inspection operations should be done in advance. The supply order and specifications of the concerned supply should be studied carefully.

5. Continue 3. Prompt Inspection: Defective construction is prevented by prompt inspection. The inspector should make sure on every inspection of work that the defects pointed out on previous occasions have been rectified. 4. Necessary Degree of Quality Control: Necessary degree of quality control should be ensured. The frequency and details required in inspection should be such that necessary degree of quality control is maintained. 5. Inspection Organising: The inspection should be organised in such a manner so that it is completed within the time available for it. 6. Decision about Boarder Line Cases: The inspection may show boarder line cases at some occasions. Such case should be handled by setting up a definite procedure. The material purchased if does not fulfil the requirement of quality control should not be used on important works as it will reduce the quality of work

6. Continue 7. Use of Inspection Records: For carrying out inspection successfully the following should be used: Control Charts Statistical data Inspection devices 8. Stages of Inspection: The following are the important stages of inspection of construction works: Generally the materials are inspected at the place of suppliers and checked again at site to ensure that supply is according to the approved samples or nor Before using the material in any operation, the material must be checked thoroughly The tools to be used for construction work, should be inspected before and after their use. The number of inspection should be adequate. Very frequent inspections cause interruption to work

7. Inspection Practices The following inspection practices are usually recognised as the main steps leading to the control of quality through inspection Control over Raw Material and Equipment: the raw materials required for the project should be inspected at the source of supply to avoid sub-standard material coming to the site of work. Similarly, equipment to be purchased should be inspected preferably at the place of suppliers to avoid unnecessary botheration and expenses for transporting back the equipment, which is rejected Inspection at different Stages: The raw material are inspected preferably at the place of suppliers and checked again at site to ensure that the supply is in accordance with the approved samples The material must be checked thoroughly before its use in the particular operation The tools issued to the job are inspected before their issue and also immediately after use when these are taken back 3. Plan the Inspection operation: The work of carrying out inspection should be planned in advance. The supply order and specification concerning should be studied carefully. The major areas of inspection and defects to be looked into, may be visualised before hand so that the inspection is not carried out haphazardly

8. Continue 4 .. Inspection to be done promptly: the inspection should be done frequently as prompt inspection helps in preventing defective construction. The defects and discrepancies so pointed out, are rectified promptly, easily and without incurring heavy amount. 5. Inspection to be completed in time: The inspection should be organised in such a manner that it is completed within the time available. 6. Decision about Border Lines cases : if the material is not as per specifications, it should not be used on the project as it will reduce the quality of work. The material having minor defects, if accepted, at reduced rates, should be in small quantity and should be used on minor works of repairs, where quality is not of prime importance. 7 . Make use of Inspection Records Statistical data, control charts and inspection devices are often used for carrying out inspection

9. Technical Services required for Inspection Different processes of inspection and tests are conducted to control quality of construction and to ensure that the construction is sound and as per laid specifications. The following services are required for inspection. Engineer/Designer/Architecture/geologist 2. Supervisors 3. Scientists 4. Technicians 5. Field Laboratory 6. Base laboratory Equipment testing and repair unit Small works are inspected by the site engineers, who should be experienced person having good practical experience of construction works. The inspecting engineer should have through knowledge of design of structures. He should know the latest techniques of construction and should keep himself informed about the modern development in the field of construction. On large projects, the inspection is carried out by specialists e.g., surveyor, geologist, architect etc. besides the engineer- incharge as mentioned below: Geological examination of soil, including sub-soil exploration is done by the geologist, who should thoroughly examine the sub-soil for its composition and bearing capacity before the structure is erected over it. The meteorologist gives his expert opinion regarding climatic condition of locality Checking of design of structures is entrusted to the design engineer. The layout is checked by the specialist/surveyor, thoroughly, as any discrepancy in layout results in faulty construction.

10. Quality Control Quality is one of the vertex of the construction management triangle (time, cost, Quality). For a project context quality control refer the maintenance of the construction work as per the technical requirement stated in the technical specification of the contract document. Quality control is achieved through regular inspection as per the frequency determined in the quality manual for different kind of work. Important documents required for the quality control are: Technical specification of the project Project quality plan Work method statement for different works like plastering, brick work, concreting Inspection and test plan Acceptance criteria of materials and work as per technical specification

11. Major Items In Construction job Requiring Quality Control Excavation: This is first activity executed at site. To start the work ensure the centreline drawing of the foundation is available clearly showing the levels. Centreline layout at ground by lime powder should be check several times in accordance with the drawing. Determination of groundwater level is also important. If the ground water table is above the bottom of the excavation level then proper arrangement dewatering have to be done. Concrete: F or small work it is specified as nominal mix and for large works it is specified as controlled mix. In both the cases adequate control should be made on quality of materials and the processes of mixing, placing, compacting and curing. The minimum quantity of water should be used so that the concrete result be tested the specified slump value. The initial setting time of cement must be kept in mind during the mixing of water and find completion of concrete. Steel: steel is the major item of expenditure in most of the works and very costly. There should be minimum wastage in structural work. Steel used in reinforced concrete should be checked carefully to ensure proper bending, binding, placing and proper shape and spacing of bend bars. Before using the bars it must be checked that the bars are rust free, scales, oil and other harmful coatings. .

12. Continue Form works: The form work must be strong to support the wet concrete and have a smooth surface so that the finished concrete does not require much amount of rendering when the concrete is not required to be plastered, the pattern left by the form work should give a pleasing effect Masonry work: The brick should be of specified quality and have required bearing capacity when used in load bearing walls. The bonding should be maintained properly. The dimensions of masonry work should be properly controlled. Water proofing work: T his is also very important item of control. The damp proofing of roofs, etc., is very important item of quality control. Joinery and Timber Work: The quality of timber and workmanship in joinery are very important items of quality control special care and attention should be paid for the same. Sanitary and water supply: For a good post construction performance of a building proper installation of sanitary and water supply line and fittings are very important. Numerous joints and fittings attached in the system of the network and some part of the network is open and some part of is embedded. Any leakage in embedded part will lead to water seepage in wall and wet patches will be visible. Therefore joints must be water tight with jute cloth for cast iron and chemical solution for PVC/UPV/CPVC pipes.

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