Sika® ViscoCrete® SKY 8703

Sika® ViscoCrete® SKY 8703 is a new generation superplasticiser with super retention technology. It contains polycarboxylate ether polymers and is specially formulated for ready-mix concrete where slump retention, high strength and durability are required in hot climates. The excellent dispersion effect makes Sika® ViscoCrete® SKY 8703 the ideal admixture for the ready-mix concrete industry. The ability to work with low water /cement ratios and still obtain extended slump retention allows for the manufacture of high quality concrete.

Sika® ViscoCrete® SKY 8703 is free of chloride and complies with BS EN934: Part 3: 1985, and is also compatible with all cements meeting recognised international standards.

Chemistry and Mechanism of Action Conventional superplasticisers, such as those based on sulphonated melamine and napthalene formaldehyde condensates, at the time of mixing, become absorbed onto the surface of the cement particles. This absorption takes place at a very early stage in the hydration process. The sulphonic groups of the polymer chains increase the negative charge on the surface of the cement particle and dispersion of the cement occurs by electrostatic repulsion. Sika® ViscoCrete® SKY 8703 is differentiated from conventional superplasticisers in that it is based on a unique polycarboxylate ether polymer with long lateral chains. This greatly improves cement dispersion. At the start of the mixing process the same electrostatic dispersion occurs as described previously, but the presence of the lateral chains, linked to the polymer backbone, generates a steric hindrance which stabilises the cement particles capacity to separate and disperse.   This mechanism provides flowable concrete with greatly reduced water demand.