Self compacting concrete or self consolidating concrete (referred as SCC) or Highly Fluidized Concrete, a type of high performance concrete, is able to flow and consolidate under its own weight. The technology firstly appeared in Japan in the 1980s and according to the composition of the mortar, SCC can be divided into three different types: Powder type--uses a high proportion of fines to produce the necessary mortar volume, Viscosity agent (stabilizer) type--the fines content can be in the range admissible for vibrated concrete and the viscosity required to inhibit segregation will then be adjusted by using a stabilizer., Combination type--adds a small amount of stabilizer to the powder type to balance the moisture fluctuations in the manufacturing process. SCC is also cohesive enough to fill spaces of almost any size and shape without segregation or bleeding. This makes SCC particularly useful wherever placing is difficult, such as in heavily-reinforced concrete members or in complicated formwork.
Compared with normal concrete, in SCC mix design, it increases the amount of fine material like fly ash or limestone filler without changing the water content, which changes the rheological behavior of the concrete. SCC needs a low yield value to ensure high flowability and a low water content to ensure high viscosity, so the coarse aggregate can float in the mortar without segregating. In order to maintain a balance between deformability and stability, the total content of particles finer than the 150 µm (No. 100) sieve has to be high, usually about 520 to 560 kg/m3 (880 to 950 lb/yd3). High-range water reducers based on polycarboxylate ethers are typically used to plasticize the mixture. SCC is very sensitive to fluctuation in water content, therefore, stabilizers such as polysaccarides should be used. In investment cost of the production of SCC and the normal concrete , SCC is more expensive than regular concrete and it is difficult to keep SCC in the desired consistency over a long period of time. However, shorter construction time, environmentally friendly (no noise, no vibration) in addition to a good surface finish that SCC can produce make SCC particularly interesting for use in precasting plants.