29. 10. 2021.

SELF-COMPACTING CONCRETE

Luxury or inevitability?

Innovative types of concrete, specially designed upon requirements of projects applying the state-of-the-art technologies are becoming more and more present on domestic market. Modern building trends, and even more importantly, demanding dynamics of works execution, requirements for faster, high-quality and more durable building, initiated development of new types of concrete that can address each design’s task. In addition to a high-quality cement, Lafarge BFC Company has been recognizable on domestic market also for high-quality types of concrete, both standard and innovative, i.e. specially designed and custom-made according to specific market demands.

A special concrete of Lafarge’s portfolio – Agilia™ has been increasingly used on construction sites all around the country. It comes from a range of self-compacting concretes – SCC, characterized by ability of installation without vibration. SCC concretes had been developed within last decades of the previous century in Japan, USA and Western Europe and became irreplaceable at structures with densely placed reinforcement, followed by high-strength requirements and short-term deadlines of works execution.

While designing this type of concrete, the focus is placed to ability of material to spill under the effect of its own weight, fulfilling completely the planking, regardless of its shape and dimensions. One of the requirements for the concrete is to easily pass through densely placed reinforcement, while maintaining homogenous structure without separation of aggregates from the paste or water from the firm phase (“bleeding”), also with no tendency of a large aggregate separation from the concrete under the effect of gravity (segregation).

Basic components of the Agilia™ concrete are the same as of standard concrete. They differentiate in various ratio of small and large aggregate, higher quantity of small particles in a cubic meter of concrete, as well as application of chemical additives of the latest generation that enable proper fluidity of concrete (super-plasticizers of the third generation with high ability of water reduction in concrete and viscosity modifiers).

If properly designed and installed, the Agilia™ concrete is characterized with increased compactness and homogeneity. Global experience undoubtedly prove there is a certain difference between properties of hardened self-installed and vibrated concrete of a similar recipe and same water-cement factor, even certain properties are being improved at SCCs. Higher strength values upon pressure and improved properties, such as adhesion to the reinforcement, also permeability of air and water are related to decreased porosity of internal transient zone between cement paste and aggregates, as well as better micro-structure of SCCs in general, compared to standard concrete. Production of the Agilia™ concrete does not require different procedure – classic mixer is used, but it’s necessary to control the content of moister/water of which this special concrete is susceptible to.

Avala Tower, self-compacting concrete application

New technology of concrete production used for Agilia products accelerates process of concrete installation, considering excellent concrete leveling that eliminates requirement for additional processing of horizontal concrete surfaces, decreases number of positions and operations on site, also use of crane, at the same time providing excellent concrete quality with finishes of exquisite aesthetic properties.

Use of self-compacting concrete increases flexibility on sites at all positions and for all application (piles, foundations, finishes, horizontal and vertical surfaces). A curiosity is the fact that the use of Agilia ™ concrete can cast structures of very complex shapes, especially in cases of dense reinforcing mesh and long planking.

With horizontal installation, the impressive ease of leveling the concrete allows for quick and easy coverage of large surfaces and flat finishes. Also, Agilia ™ wraps the reinforcing mesh in deep foundations more effectively than all other available concretes.

The design of the Agilia ™ recipe stems from strict control and compliance of two seemingly opposite physical properties: fluidity and stability. The fluidity of the concrete is necessary to enable easy installation and high surface quality without additional finishing works. At the same time, fluidity can increase segregation, which in turn can lead to uneven material properties, cracks and stains. On the other hand, there is a need for stability in order to prevent segregation, but it can lead to increased viscosity and poorer installation of concrete. Combining these two opposing properties is a great challenge, given that fresh concrete is subject to different influences during transport from the concrete base to the installation site, and depending on the production process, environmental protection requirements and application.

Agilia™ offers a reliable solution based on the concepts of granulometric packaging and the latest discoveries in the field of organic and inorganic chemistry, as well as fluid mechanics applied to fresh concrete. Strict control of the technology used enables optimal application of cement properties, allowing the concrete to retain its embeddability for up to two hours. The use of Agilia ™ eliminates the need to add water on the construction site. The setting time of concrete is controlled, while the early strengths are at the level of the strengths of conventional concrete.

Application of the Agilia ™ concrete

Kalemegdan walkway, Belgrade

The walkway that connects the Belgrade Fortress and the Sava Quay, opened to the public in May last year, is one example of the use of Agilia ™ concrete. The Kalemegdan Bridge project was developed by Serbian and British sculptors Mrdjan Bajic and Richard Deacon, with the support of architect Branislav Mitrovic, who additionally designed the project, taking into account all aspects of this interesting endeavor, and above all the purpose of the building and its implementation in the environment. The realization of the ambitious project was contributed by the application of Agilia ™ Lafarge concrete, which, thanks to all its above properties, enabled the project to achieve the desired effect of “sculpture” with smooth and elegant surfaces, with the necessary strength and stability expected from this type of construction. Lafarge experts actively participated in the development of the project and preparation of an adequate solution together with the author’s team and engineers from the Traffic Institute CIP, in order to comprehensively apply the standards related to aesthetics and technical execution of the project.

Kalemegdan walkwaz, Belgrade, application of Agilia concrete
LingLong Tire, Zrenjanin

Lafarge Agilia ™ concrete was used on the currently largest industrial construction site in Serbia – the Linglong Tire tire factory in Zrenjanin. For the foundation of an imposing industrial complex on over 100 hectares, a specially designed concrete for piles, Agilia Piles was used, which is characterized by a reduced CO₂ content of 30% compared to classic concrete for piles. Namely, self-compacting concrete for Linglong Tire is produced from CEM II / BM (SV) 42.5N LH – low heat hydration cement, which is characterized by the lowest CO₂ emission per ton of cement in Lafarge BFC’s bulk product portfolio, and was developed as part of the Lafarge BFC’s strategy aimed at reducing the industrial footprint on climate change.

At the Linglong Tire construction site, the foundation was made using the CFA method, Ø600 and Ø800 in diameters, at depths of up to 30m, which requires exceptional mobility of the concrete in order to enable placing down of the reinforced basket with its entire length into the pile hole on one hand, and homogeneity on the other, in order to avoid segregation and stratification.

LingLong Tire, Zrenjanin, application of Agilia Piles concrete for piles construction

Agilia Piles, produced from CEM II / B-M (S-V) 42.5N LH, is the first concrete for piles in Serbia with a drastically lower CO₂ content, which ranks it among the so-called green concrete, the development and implementation of which in the local market is being worked on intensively at Lafarge.

The fight against climate change is a key strategy both at LafargeHolcim on a global level and at Lafarge BFC in Serbia, where the company has focused its activities on leadership in the field of green building with the application of state-of-the-art solutions. Advocating for sustainable development, Lafarge BFC focuses on innovations adapted to local conditions. The contribution is aimed towards the implementation of the strategy through the development of a portfolio of a range of new products with the lowest possible emission of harmful gases, both cement and concrete, as well as the promotion of circular economy solutions.

Development of self-compacting concretes

Development of SCC is related to the eighties last century in Japan. One of the initiating factors to start research in this direction is the occurrence of accelerated deterioration of reinforced-concrete structures, primarily in the coastal areas of Japan. The problem of durability of structures, as concluded, was closely related to a corrosion of reinforcement in concrete, caused by carbonization of protective concrete layer and aggressive effect of chloride ions. On the other hand, lack of qualified workers affected development of materials which use would minimize engagement of workers for concrete installation.

Over the past 30 years, numerous congresses and seminars dedicated to the development of SCC concrete have been held around the world, and various scientific research projects have been conducted within which the properties of this material have been studied and improved. Today, self-installing concrete is irreplaceable on certain projects, primarily on structures with densely placed reinforcing mesh, where high strengths are required, and the dynamics of work is very ambitious.

Many capital facilities in the world have been built thanks to self-installing concrete. Domestic experts, following the world’s knowledge and experience, also join the users of SCC concrete, which, thanks to its characteristics, is known as the revolutionary discovery of the concrete industry of the XX century.

RMX plants and technical support

Lafarge Company disposes of large number of RMX plants, including mobile facilities placed on sites, custom-made for each individual project with full service including the logistics, production, quality and transportation of concrete. Lafarge RMX plants use different types of cement, with special attention devoted to the granulometric composition of aggregates; use of state-of-the-art measurement devices, precise dosing of intake components of concrete, as well as delivery of accurate quantity of concrete to customers is provided constantly. Mixer trucks of capacity 7m3, 9m3 and 10m3, as well as the concrete pump with hand length of 28m, 36m, 39m and 41m are used for Lafarge’s concretes delivery.

Lafarge’s RMX plants provide services such as fresh concrete cooling during summer, as well as concrete heating during winter months, which completes concrete delivery offer to the entire year and provides availability of quality concrete to customers at any time, observing a demanding projects dynamics.

Lafarge RMX plant, Ada Huja

The oldest cement plant in Balkans

Lafarge BFC is part of the LafargeHolcim Group, founded in 2015 by merging two global leaders in building materials industry: French company Lafarge and Swiss company Holcim. Lafarge is operating in the cement plant in Beocin, which is modernized and fully compatible with the highest global standards in sense of efficiency, environmental footprint and H&S, also operates several RMX plants in Serbia.

Beocin cement plant is one of the oldest and largest cement plants in Europe, the oldest in Balkans with history dating since 1839. During its long-lasting history, Beocin plant produced materials for some of the most significant, capital buildings in the country, such as the hydropower plant Djerdap, Avala Tower, Beska Bridge, Ada Bridge, Corridor 10 and 11, Pupin Bridge, Cibuk wind farm, Belgrade-Budapest railroad, etc.

Appearance of the factory from 1869.