Despite the seeming simpleness design of safes, bank vault doors, and other means for safe storages, their manufacturing construction should be based on advanced technologies and effective design solutions.
The protective layer of armored safes, doors and covers bank vaults - is a complex fiber reinforced construction filled with concrete mix. The quality of the concrete largely depends on the level of construction resistance to the breaking load. A great scientific experience has been gained during 1960-1980 in Ukraine. The fundamentals of concrete hardening theory and means of strength ensuring of reinforced concrete structures were developed. All these innovations form the basis of the bank protection construction means, particularly, storages.
Recently, the research range in this area has significantly reduced. Today mixed concrete plants in Ukraine is not able to provide the required quality and strength of concrete. For example, it is necessary to use at least M500 concrete brand to make storage with high-end stability to breaking, while the majority of Ukrainian factories produce unstable quality concrete (M400 by a long stretch of the imagination). The use of such concrete can result the mismatch of the claimed storage class and real, which is absolutely unacceptable. So, we use only self-made concrete. Our Scientific Technical Centre has developed a comprehensive project that includes two main areas:
Widely used structural concrete is known since the 19th century. Common concrete is a fragile material, so its sudden destruction occurs upon reaching the critical load. Concretes, used in our industry, are quite different from those, which are used in the residential and industrial building. Thanks to our own researches and developments we were able to significantly improve usable concretes. Used concrete in a protective layer must withstand targeted impacts and therefore should have some additional, special properties. Adding of steel fibres in concrete improves the strength characteristics of concrete, the fibre-concrete product will not crack until high deformation appearing.
Firstly fibre concrete was prepared in 1962, when Romaldi (USA) was able to significantly increase the strength of concrete by adding direct steel fibres of wire. For today, fibre concrete - a highly efficient structural material, which properties can be managed in a rather large range.
There are many theoretical preconditions to get native concrete with 1500-2000 kg / cm2 strength. Practical achievement of these indicators is difficult, but possible. We have set the goal and move towards it step by step. The technology for producing high-quality multi-functional concrete of new generation is widely used in Europe. These concretes are called “highly functional concrete” - self-compacting concretes (High Performers Concrete). The production of such concrete is possible only in conditions of high production standards, providing:
We have created a theoretical base and developed study methodology of the various plasticizers effect on the strength of concrete, found optimal parameters ratio of fibre and solid fractions. We have also systematized the requirements for cement, sand, gravel, and introduced a system of strict control of supply of these materials. All this has allowed us to get fibre concrete with guaranteed performance M700-1100 kg / cm 2, and to identify ways to further strength increase of concrete by 25-30%.
Together with research of high-quality concrete production based on native raw materials, we look for advanced production technology of special grades of concrete, which would be maximally useful to our industry specific. The developments of «Densit security» (Denmark) are in great interest for our company. After all available material analyzing and visiting the plant of the company, we have seen that Densit-technology makes a possibility to get a splendid end result (up to 3000 kg / cm 2). Herewith, the technology of protective layers manufacturing, based on Densit cement, brings excellent results during tests on crack resistance. Danish developers have considered the methodology and test features of almost all European test centers. Densit-technology includes the optimization of the basic parameters that have an effect to the strength of concrete: high-strength cement, graded aggregates with high toughness, fibre for the micro-structure of concrete and cracking prevention.
Compared to ordinary concrete, Densit fibre concrete has the following advantages:
The calculations of load capacity of Densit fibre concrete structures have confirmed the possibility of covering panels manufacturing up to 9 meters, which enables to build storages of large area without columns. High protective properties of Densit enabled to reduce protective layer thickness, as a result, to receive the following advantages:
The following parameters can illustrate this:
|Breaking Resistance Class||Layer protective thickness, mm|
|ISO 4012.1-2001||fibre concrete
The use of thin-walled protective structures often becomes the only possible solution for the reconstruction of existing storages to improve the previously assigned class. Though, the size of construction works and costs are minimal.
All leading European manufacturers use Densit Technologies. On the basis of foreign and native building experience, we can argue that the current fibre concrete Densit - is the most effective material for safe storage facilities (bank vaults, vault doors and safes of high grades).