Quality control in civil engineering - a perspective
The quality control of materials used in civil engineering concerns, among others, the qualitative and quantitative analysis of each material being used in construction of building structure and road work. In general, there are three main domains of construction quality control to consider: soil, concrete and asphalt. Along with these three main domains there are many more products which are associated with the building structure and road construction work, for example: steel, PVC (Polyvinyl chloride) products such as water stoppers, swell bars, adhesives (admixtures, epoxies, sealants etc.). If we discuss practically all the products for the construction site, it is quite interesting to tell you guys that over 300 hundred tests are being applied to ensure quality of site work.
Now, how to ensure that even the smallest grain of soil will be suitable at the construction site? For the analysis of each product, laboratory work is needed in order to design and assure the qualitative performance of all the equipment, chemicals and materials. One example during my work in the site is the filling material or sub grade or sub base or aggregate base, which is ordered for the highway project M-09 Karachi.
Testing completion according to the standard gives to the vendor the authority to either use the source or not, and whenever the source is approved, the material will be checked periodically. To find similarities you can think of a medical laboratory where medicines are tested and where it is extremely important to ensure their efficiency. The approval of the product suitability to the market will be in the quality control hands. So, quality control of construction industries does play a life-sustaining role for the building structure and the road pavements. Moreover, without material engineering it is really not possible to step forward confidently for the single material to be used in the structure of a building or a road.
As a quality control responsible, it is important to start the evaluation from the natural ground. Here, the strata composition can vary from loose soil to hard rock and it is necessary to perform geotechnical tests for assuring that the natural strata can bear the structure load or the traffic load. During my highway project, cut and fill was applied to make the natural ground level suitable according to the surveying report. Then the natural ground material sample was tested in the laboratory according to the ASSHTO T 87-86. I brought in my material testing laboratory, started particle size analysis according to ASSHTO T 88-93 to check the binder suitability. Then, ASSHTO T 89-96 was applied to determine its liquid limit, plastic limit, plasticity index to check if the natural ground is suitable for the highway structure.
Similarly, every layer of pavement structure such as embankment, subgrade, sub base, course aggregate base and then finally asphaltic layer used to be tested in the same way according to the world wide approved standards where quantity of tests can vary, like sampling of aggregate (ASSHTO T 2-91), specific gravity and absorption of aggregate (ASSHTO T 84-95), abrasion test in loss Angelou's machine (ASSHTO T 96-94), soundness of aggregate (ASSHTO T 103-94), clay lumps and friable particles in aggregate (ASSHTO T 112-91) and so on. Asphaltic and concrete layer are a complex topic. These are the most expensive materials so they require significantly more testing with more advance laboratory equipment.
All in all, the quality control is simply a "must" to ensure the quality of materials and processes at the construction site. It is a set of essential tools and standards that guide the engineers and facilitate their work. Construction sector is an area where mistakes might have fatal consequences - and quality control aims to prevent them.