Self-placing and self-levelling concretes
CONCRETES THAT ARE PLACED WITHOUT VIBRATION
Knowledge acquired in the course of resarch into HPC and increaing expertise in the use of the new superplasticers that have been developed in recent years, have made it possible to develop a new type of concrete: self-placing concrete which profoundly alters the organization of works, making it possible to make structures with complex forms and a large amount of reinforcement. At the same time, the facings are of high quality and the comfort and safety of workers is improved (elimination of vibration).
Self-placing concretes are extremely fluid, homogeneous and stable (free from segregation) and are placed without vibration. They are marked by a great capacity to flow without losing stability, pumpability and longlasting fluidity and differ from ordinary concretes mainly as regards their properties in the fresh state, which is an optimal compromise between fluidity and resistance to segregation. When hardened their performance is similar to that of conventional vibrated concrete.
Self-levelling concretes are a type of self-placing concrete suitable for horizontal surfaces (slabs).
Self-placing concretes have many advantages:
Thorough coating of reinforcement and optimal filling of formwork
Improved working comfort and safety at worksites
Increased productivity and labour savings
Aesthetically pleasing appearance.
Self-placing concretes are particularly appropriate for structures:
where high quality facings are required (no variations in colour or texture, perfectly smooth, absence of segregation and blowholes).
high densities of reinforcement (bridge decks)
narrow high shells (bridge piers)
places where access in order to perform vibration would be difficult or impossible
complex shells with many reentrants.