Construction World November 2017

ADMIXTURES

OPENING DOORS for concrete INNOVATION in design and construction

The growing range of concrete admixtures from Chryso Southern Africa is changing the face of construction by broadening the options available for both designers and contractors, according to general manager: marketing and commercial sales, Hannes Engelbrecht.

A recent showcase of what can be achieved using high strength concretes and specialised admixtures, says Engelbrecht, is the recently opened Museum of European and Mediterranean Civilisations (MuCEM) in Marseille, France. Designed by architect Rudy Ricciotti, the concrete structure includes a 115 metre slender ‘super-concrete’ pathway linking the MuCEM to the Fort Saint-Jean. Without arches or stays, the concrete path is a testament to ever-improving concrete technology and strength. Engelbrecht highlights other technologi- cal advances in admixtures that give design- ers the opportunity to apply ideas that they could previously only imagine. “While most contractors are familiar with traditional applications of admixtures – such as the water reduction, plasticising and acceleration or retardation of setting time – there are so many more applications that are now available to improve quality, safety and aesthetics,” says Engelbrecht. “So committed is Chryso to constant innovation that 35% of our products are less than five years old.” Decorative and functional One of the most recent product lines is LuminTech, an impressive new addition which facilitates decorative yet functional concretes. This remarkable range contains a variety of different luminescent particles

“With the use of admixtures, concrete structures can be made stronger, higher and thinner,” says Engelbrecht. “An important aspect of these high strength concretes, however is their low water/binder ratios; this requires a very powerful polymer to disperse the cement and ensure mixing efficiency.” In South Africa, he says, about 95% of all concrete being batched is conducted in dry batch plants which rely on readymix truck drum mixers to mix the concrete. Without the correct admixture, the level of dispersion of cement in the drum could fall short of what is optimally required. This mixing efficiency is particularly important when contractors want to achieve higher strengths, as is often the case today. “Our admixtures offer unique technology to give contractors the mixing efficiency to achieve the cement dispersion much quicker,” he says. “With high paste volumes, it is also difficult to maintain the workability of the concrete; our LSS technology therefore gives the customer the necessary open time to place the concrete.”

Included in the range are Rover technologies (incorporating robust and versatile qualities) which are specifically aimed at ultra high density concretes, and fill-free technology where there is a need for high flow concrete to have superior mobility in particular appli- cations. The latter, he says, comes without the adverse effects on the strength and setting characteristics, which characterise certain viscosity modifiers. Becoming more complex “It is important for customers to realise that the field of admixtures has become complex and application specific, so using these products optimally really requires users to consult with their admixture suppliers in the early stages of projects, in terms of structures being constructed and what results they require,” he says. Chryso’s new Centre of Excellence is a laboratory facility where cements and aggregates may be evaluated, helping the customer to determine the optimal mix design to suit the customer’s purpose.

The iconic Museum of European and Mediterranean Civilisations (MuCEM) in Marseille, France.

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CONSTRUCTION WORLD NOVEMBER 2017