Quality control of building materials has been tightened in Georgia. Namely “Technical Regulations on Building Products” implying supervision of cement, rebar, electric cables and plastic pipes, has entered into force since January 2019. According to the new regulation, supervision, assessment, allocation and import of these products should be implemented in accordance with the European standards.
Since the technical regulation started – do we have the increased number of testing of building materials in the laboratory, what is their quality, how should the building products be tested and who mainly addresses the laboratory, with all these and other questions we addressed the Head of Training, Scientific and Expert Laboratory at the construction faculty of the Technical University, Vitaly Dvalishvili.
– How should customers check building products?
All lots of rebar delivered to the construction site must be sampled. One-meter piece must be cut off from the middle part of three different bars of each diameter. The samples will be processed and tested in the laboratory for tension and bending. The results will determine the class of rebar.
As for the concrete, the control samples are taken in the process of filling with concrete. The samples remain for a period of 24 hours on the site in the same condition next to the real structure, its transportation untimely before drying, may cause segregation. After its transportation to the laboratory, the samples are kept in the special regime camera. The first sample will be tested 7 days later, the rest – 28 days later.
– Has the regulation increased the number of those addressing the laboratory to test the building materials? If yes, who are they?
The concrete had also been intensively tested before, the demand for cement testing has been increased as well, but the demand for rebar testing has significantly been increased. Testing is usually required by the customer as well as by the builder. As for this ordinance, we have frequent cases when importers are also interested in testing of materials.
– What is the quality of rebar produced in Georgia?
We do not considerate right to say that Georgian rebar is bad or vice versa. There have been cases of bad quality local as well as imported rebar, but mostly it is good.
– What about cement, what quality is it?
More quantities of low quality cement occur to be in the market in spring and August, when demand is high and everything can be sold. Today’s norm for cement activity should not be less than 32.5 MPa, however sometimes it is not at least ten. As a rule, such kinds of cement are not sent to large objects, high-rise buildings. But it should be noted that the situation with cement has been improving slowly.
– How would you assess construction quality in Georgia?
In general, many things depend on the builder. There are construction companies trying to observe the rules the best, test concrete and rebar, knowing how to care of concrete. In summer, in construction process in Tbilisi, rebar is usually placed on the top floor of the building and heats up to 60-70 degrees. It is so simple, before filling with concrete, rebar should be cooled, otherwise the concrete is cleaved. The experienced builder always takes it into account, though sometimes it is said that the concrete itself will cool overheated rebar, and as a result the concrete is cleaved, because the temperature expansion coefficient is approximately the same for both concrete and rebar, so tightening is provided between concrete and rebar. When concrete is placed on hot rebar, it begins to cool and its compression is started as well as concrete is compressed. When the latter is new and not hardened, it has no resistance and wet concrete is cleaved. However, such facts are not frequent, but such cases occurred to be due to carelessness.
– What is your opinion, should the quality of the construction be controlled or not?
As far as I know, at present the quality of the site is the responsibility of the client. In the Soviet period the state commission meeting was held after the construction of the residential building had been completed. All specialties were presented into the commission, including firemen, electrician, etc. Each specialist signed in his field saying that the house was ready for exploitation. The acts of secret works were presented for the commission and should have been signed by the author of the project and the record manager, for example, this kind of rebar is used in construction and corresponds to the project, there was copyright supervision as well. Today some of our customers do not spend money on copyright supervision. But I think, the control is necessary and the clients should also be interested in it, as in the case of any accident, not to be the only responsible for it. In recent period, the quality of construction in Georgia is quite high. However, high-class builders are needed in order to develop the construction sector, we also need to apply new technologies, control materials and observe technological regulations.
Magazine “Construction Solutions”