What is the Big Innovation
Self-compacting concrete falls into the category of newer concrete production technologies, consequently, its properties have not yet been sufficiently investigated. The intention of this work was to obtain knowledge of the physical and mechanical characteristics of this concrete with a special focus on its resistance to low temperatures, chemical aggression and a possible segregation occurring in sections of greater depth.
The above mentioned characteristics of self-compacting concrete, which can be crucial for its durability in the exploitation phase, have not been sufficiently discussed in the literature. Moreover, there have been examples in practice when due to insufficient knowledge related to the characteristics in question, the concrete suffered damage that was caused by these effects. With this study we tried to determine how this type of concrete behaves when subjected to low temperatures and chemical aggression, and to acquire knowledge concerning the segregation characteristics during its casting in sections of greater depth.
Self-compacting concrete is produced by adding special superplasticisers (new generation) that enable the mould and formwork to be filled with concrete under its own weight only, while simultaneously the trapped air is being released in the absence of vibration.
In construction industry there is a constant growth in the application of new building technologies accompanied with the use of new materials. When designing modern structures the tendency is to reduce the quantity of the material used while increasing its efficiency, to reduce manpower and lower the total cost of construction. In Japan, the country where it was originally created, the utilization of self-compacting concrete is becoming common.
In general, it could be concluded that the application and fabrication of self-compacting concrete entered the phase of common usage.
The next step to expect is the evolvement of a technology that would enable a more efficient and faster production. A growing utilisation of this concrete is apparent in our country as well. The cost of self-compacting concrete does not different from that of the conventional concrete of the same class, since the increased cost of the mixture is compensated by the reduced cost of placing. In addition, more reliable quality of built in concrete and lower maintenance cost are in fact a net profit and not a small one.
Self-compacting concrete opens up new possibilities for use, which considerably surpass the possibilities of conventional concrete:
- application in densely distributed reinforcement
- for complex geometric shapes
- for thin cross sections
- in all cases where vibration of concrete is difficult
- for demanding homogeneous concrete structures
- for fast placing
- for the reduction of noise (elimination or reduction of vibrations)
- for the reduction of harmful effects on health (syndrome of white joints)
Two basic, but in essence incompatible tendencies, dominate the production of every concrete:
- to make the most workable (plastic) fresh concrete as possible
- to produce a hardened concrete of the highest quality