High strength white concrete for mosque

In September, Europoles delivered 618 supports made from white, high strength spun concrete for the third largest mosque in the world, which is to be built in Algiers. The pole manufacturer produced the concrete for the up to 34 m, 34 t columns using twin-shaft mixers from the BHS-Sonthofen DKX range.

The mosque, erected by a Muslim community in the Algerian capital, is costing around €1.1 billion, and has a capacity of 35 000 people. The production of its octagonal supports was therefore not a standard project. The 32 largest of the supports are 34 m long and 1.62 m dia. The last of the poles are to be transported by the end of September 2015.

To undertake the project, Europoles required a new mixer, as the mixing times of the existing planetary mixers would have been too long, and a separate mixer was needed for the delicate white concrete in order to avoid contamination.

Even beyond the mosque project, the interest in high strength and ultra high strength concretes is constantly rising, and as such Europoles wanted to use the investment in a new mixer to prepare for future projects. As high strength concretes need to be mixed intensively to achieve good homogeneity, the focus is placed on short mixing times and the correct mixing procedure, in order to allow for the production of up to 20 m³/hr. This instantly excluded several mixing procedures from consideration. Additionally, the new mixer needed to be integrated into the current building without any need for significant conversion work, meaning that a compact mixer was the only option.

In order to meet both of these requirements the Europoles plant technology department finally decided upon the most powerful and fastest mixer that could be accommodated in the existing installation space – a DKX 1.25 with a rated output of 1.25 m³ of hardened concrete per batch. Due to its high filling degree, this mixer type is extremely compact while providing the required throughput. As a result, little alteration was required to the existing facility. A recommendation from the adjacent concrete plant also aided the decision.

With the schedule fixed for the delivery of the columns to the mosque, the timeline for commissioning and delivering the mixer was extremely short. The order was placed in April 2013 and concrete was being produced just 6 months later.

On a normal production day, the new facility mixes up to 16 batches of concrete per hour, achieving an output of just under 20 m³ in this time. For the mosque project, up to four columns per day have left the plant at peak times, each of them with a weight of up to 30 t.

Bernhard Matschiner, responsible for the upgrading of the mixing plant for the mosque project, is pleased with the results so far: "Beforehand, we were only able to produce white concrete in very limited quantities, since the mixing times using planetary mixers were much too long. The homogeneity of the concrete produced with the BHS mixer is excellent and it works extremely reliably with high availability. We can now also reliably produce large quantities of high-grade UHPC. Thanks to the new mixer, we've been able to significantly improve our market position – especially with regard to our competitor material, steel. In the future, we will be offering products whose quality and price are superior to those of steel."

Adapted from press release by Rebecca Bowden

Read the article online at: https://www.worldcement.com/africa-middle-east/15092015/high-strength-white-concrete-for-mosque-546/