Self-compacting concrete (also known by its acronym HAC or H 30 AC) is a type of concrete that is characterized by its ability to flow and fill any part of the formwork solely by the action of its own weight, without requiring compaction by mechanical means, and without blocking or segregation: hence its name self-compacting.[1] This type of concrete runs between the formwork and the reinforcement. "Armor (construction)") without the need to apply internal or external compaction means and remaining, during its installation, homogeneous and stable without presenting segregations.

This type of concrete requires very controlled dosage of its components. In relation to other concretes, self-compacting concretes have a higher content of fines&action=edit&redlink=1 "Fines (concrete) (not yet written)") (gravel with less than 125 nm). The cost of this type of concrete is higher, however it is easier to operate with it, due to the absence of vibrating or compacting machines.

Due to the seismic characteristics The first case of self-compacting concrete was produced in Japan in 1986, by Professor Hajima Okamura) of the Department of Civil Engineering University of Tokyo. This first self-compacting concrete used granulated slag "Slag (metallurgy)") from blast furnaces and fly ash together with a specific chemical additive called superplasticizer (3% of the cement content).