QUALITY ASSURANCE AND QUALITY CONTROL
The word Quality has many meanings, e.g.:
- A degree of excellence
- Conformance with requirements
- The totality of characteristics of an entity that bear on its ability to satisfy stated or implied needs
- Fitness for use Fitness for purpose
- Freedom from defects, imperfections, or contamination
- Delighting customers etc.
Quality, in ISO 9000:2000, is defined as the degree to which a set of inherent characteristics fulfills requirements. By combining the definition of the terms quality and requirement in ISO 9000:2000, quality can be expressed as the degree to which a set of inherent characteristics fulfills a need or expectation that is stated, implied, or obligatory.
Quality is an integral part of a construction process that aims at making the product with desired functionality at every stage of its making right from conception to design to manufacturing and finishing. Quality in construction should result in satisfactory strength, serviceability, and long-term durability, so as to lower the overall life-cycle cost. Quality Management System in construction aims at ensuring unhindered service life and desired functionality of the project for the intended life span.
Quality Assurance (QA) and Quality Control (QC) are the processes employed during the manufacturing/construction of a product or service right from conceptualization to finishing to ensure that the outcome fulfills the intended standards of quality.
Quality Assurance is defined as “all activities and functions concerned with the attainment of quality” and implies the application of various management techniques. Quality Control involves measures required to verify that the specification requirements are met. It refers to various technical processes that gather, examine, analyze and report the conformance with the performance requirement. The system is required to provide reliable and accurate testing support to fulfill the quality objectives set in the designs and specifications.
PHPA-I has a well-experienced and trained QA and QC set up under the guidance of the Joint Managing Director. QA /QC wing headed by Chief Research Officer has a well-equipped Quality Control (QC) Laboratory at Gewathang, located about 7 km from the Dam site towards the Powerhouse site below the Wangdue -Tsirang National Highway. The laboratory, set up in 2012, has all the necessary equipment for routine testing of construction materials used in the project, viz. concrete & cement, reinforcement steel, aggregates, admixtures, etc. There is some very advanced equipment, which is generally not very common in site laboratories, like Universal Testing Machine (250 T capacity), Concrete Permeability Test Apparatus, Under Water Abrasion Test Apparatus, etc. Besides, this laboratory, the main civil Contractors also have their own QC and testing facilities to ensure day to day quality of the materials and processes which are further corroborated and approved by PHPA-I. The QC team of the Project aims at ensuring all materials meet the stringent quality requirements so as to achieve the desired functionality and design service life of the structures and assets.
The Quality Control Laboratory of PHPA I broadly has the facilities for conducting the following tests on various construction materials:
|Construction Material||Tests Conducted|
Fineness, Normal Consistency, Setting time, Soundness, Compressive Strengths
|Steel||Tensile Strength, Elongation, Unit Weight|
|Coarse and Fine aggregates||Gradation, Specific Gravity, Water Absorption, Mechanical Properties, Shape Indices, Soundness, Material finer than 75 micron.|
|Concrete||Slump, Compaction factor, V-B Consistency, Air Content, Compressive Strength, Density, Flexural Strength, Permeability, Under Water Abrasion Test|
|Chemical Admixture||pH value, Specific Gravity, Dry Material content, ash content.|
|In-situ Tests||Extraction and testing of concrete/shotcrete/rock cores, Ultrasonic Pulse Velocity, Schmidt Rebound Number, Field density of soil, etc.|
– Fineness (Microsilica)
– Setting time (accelerator)
– Mars Cone flow time
All grades of concrete, viz. M10, M15, M20, M25, M35 & M40, M45, High Strength Concrete (HSC), etc., Self Compacting Concrete (SCC), Porous Concrete and Shotcrete, etc. are designed and tested before using in the various project components. Aggregates from various quarry sources ranging in size from fine aggregate to coarse aggregate of sizes up to 70 mm are tested in the laboratory as indicated in the above table. Similarly, reinforcement steel of sizes ranging from 8 to 36mm is tested before using them in the structures.
The project also carried out Thermal Studies for mass concreting with the help of outside agencies and water quality tests (both for drinking and construction use), tests for long-term durability such as alkali-aggregate reactivity, deleterious material content for aggregates, harmful contents in admixtures or cement, etc. Hence, the presence of qualified personnel with an aptitude for quality assurance is the key to the success and longevity of the hydropower assets under construction.