Design of self compacted concrete with 4th generation synthetic additives

Abstract

By definition, the self compacting concrete is recognized

as a main characteristic is the capacity to flow and filling

volume of poring concrete by the action of its own weight.

The natural composition of the materials is the same for a

conventional concrete (cement, aggregates, additions, additives

and water). Its ability to be self compacting is due mainly to

the high content in fines, to the low content in fine in thick

granulometry and the high doses of additives. The present

work tackles the research carried out on self-compacting

concrete and the chemical additives used in its manufacture,

specifically the so-called last generation or superplasticizers

known as fourth generation additives or polycarboxylates.

Differentiating theme, not depending on the brand or the

manufacturer if not depending of their molecular structure,

which it results to the creation of long chain additives or short

chain additives. The key to obtaining a good HAC characterized

by a high cohesion and with self-compacting properties lies

in the correct optimization of the superplasticizer-additive

combination (viscosity modifier). Therefore, the materials used

have been the main part of the study to achieve the proposed

objectives, guaranteeing the compatibility between them,

the water/cement ratio and the achievement of established

resistances stand out. The results obtained show the goodness

of the 4th generation additives and show that the use of a

correct granulometric curve together with the use of short

chain or long chain additives gives us a significant variation

in the strength of the concrete. Giving, sometimes, the option

of dispensing with the use of different additions to obtain the

improvement of results with the use of the additives tested.