The concrete is the main building material for the load-bearing structure of the building and its foundations and is a result of the hardening of cement, water, sand, gravel, crushed stones or shingle.
When larger stones are added to this combination is being produced the so called "rubble concrete", which is used in the process of making the foundations of the buildings and other structures.
The concrete mixtures often include chemical or mineral supplements, which improve their physical properties like plasticity, increase or decrease of the time for hardening, reduction of the time for acquiring strength, increasing of the frost-resistance and others.
Since the concrete has a low tensile strength, it is most often used in conjunction with steel reinforcement, thus forming the reinforced concrete. During the construction of pavements and other more specific cases, the concrete is reinforced with steel or polymer fibers.
For the construction of solid, but less congested elements such as foundations, dam walls, gravitational supporting walls and some others, is being using unreinforced concrete.
The pouring of the concrete mixture is a process that must be well coordinated as the concrete loses its plastic properties quickly, if not poured on time. For this reason, the order of the concrete mixture should be placed when the reinforcement and the framework are completely ready.
In addition, in the cases of low or high temperatures, as well as in cases of high winds, the concrete needs extra care in order not to lose its strength.
