At the 6th International Conference on Autoclaved Aerated Concrete, ICAAC which is being held in Potsdam in early September, Master Builders Solutions presented solutions for aerated autoclaved concrete to an audience of international specialists.
Aerated autoclaved concrete is a massive mineral construction material with thermal insulation properties. It is suitable both for structural and non-structural walls and allows the production of monolithic structures meeting all the current requirements for thermal insulation, noise abatement, fire protection and moisture proofing. Aerated concrete actually consists of only about 20 percent solids and 80 percent air. It is free from harmful substances and its low specific weight combined with its high strength make it easy and economical to use on construction sites. Those are only some of its positive properties – Bundesverband Porenbetonindustrie mentions several others.
Master Builders Solutions is sponsoring the conference and Nicoletta Zeminian, Segment Manager of Manufactured Concrete Products, spoke about Master Builders Solutions solutions in her presentation “Chemical additives for optimizing the production of aerated concrete”. “Both in its composition and in the manufacturing process, aerated concrete is fundamentally different from ready-mixed and prefabricated concrete,” says Zeminian. Initial tests using additives which had been tried and tested with prefabricated or ready-mixed concrete for aerated concrete normally only met with limited success.
“To put it in simple terms, when producing aerated autoclaved concrete, setting and pore formation initiated by the addition of aluminium are two different chemical processes but they take place more or less simultaneously in the pre-curing phase,” says Zeminian.
Conventional superplasticizers can effectively reduce the water content of the mixture and therefore significantly shorten the setting time, resulting in significant cost and time savings and higher efficiency. However, they normally also increase the viscosity of the mixture and impede the aluminium reaction. Pores are not formed to the extent actually required.
Master Builders Solutions research workers have now succeeded in developing special polymers that also effectively reduce the water content but do not have any negative impact on pore formation.
The MasterCast series of additives for the production of aerated concrete effectively disperse the binder particles, significantly reducing the water content of freshly produced concrete. At the same time, the rheology of the material is improved and the pore formation process is not impaired. This way, the setting time is significantly reduced, moulds can be used more efficiently and autoclaving – a steam hardening process – can be shortened. As a result, production cycles as a whole are reduced and capacity is increased.
At many plants, the individual production steps have also been harmonized with each other to achieve maximum efficiency, which is why the main target is not to accelerate production. In this case, the main advantage of MasterCast is the possible reduction of up to 15 percent in the cement and limestone content with no change in the setting time – resulting in significant cost savings. In both cases, the energy input is considerably lower and the ecological footprint of the process is therefore reduced.
The concrete additives in the MasterCast range assist manufacturers both in optimizing their production processes and in improving product quality with respect to cost, performance, aesthetics and durability.
Other concrete additives from Master Builders Solutions reinforce this effect and offer additional security. For example, the MasterFinish range of release agents allows easier formwork removal and more efficient cleaning and maintenance of formwork in the long term. MasterPel gives the aerated concrete a hydrophobic effect; as a result, it absorbs significantly less water but remains open to the diffusion of air and water vapour, preventing moisture accumulation in the material. Master X-Seed acts as a hardening accelerator allowing the more efficient use of equipment and MasterFiber reduces drying shrinkage and cracking, improves stability and reduces the risk that aerated concrete may fracture before it is cut into blocks of the required size.
If you have any questions or need advice, feel free to contact Nicoletta and take a look at our informative brochure.