Autoclaved Aerated Concrete (AAC) production is a multi-factor process where each factor plays an important role both on mechanical and on chemistry level. Appropriate selection of raw materials, precise dosing, materials densities, temperatures of materials, amount of water, pressure, speed and time at different stages are crucial to control and optimize. Often AAC plants are not aware of the importance of the optimal set-up leading to suboptimal performance of plants. Improvements in those areas result directly in savings, product quality increase, waste reduction and even increased production volumes when cycle time is optimized.
Aircrete Europe, as a global technology partner for the AAC industry, offers assistance in improving efficiency of production in all aspects. Designing, delivering and support with operating AAC plants is the core business of the company and the innovations and know-how offered comes from years of practical experience.
Need for an AAC Additive
Understanding available raw materials and formula design is critical to make high-quality products at optimized cost in modern AAC plants. It is achieved with knowledge of the chemical process and can be further optimized with chemical additives. For decades additives and plasticizers are used in the concrete industry to increase the production efficiency and performance of the concrete. However, the production of AAC is quite a specific and delicate chemical process. The commonly-used additives from the concrete industry are not suitable for AAC production as the chemical process has different requirements.
Advantages of Poromix
Poromix is a new generation, innovative family of additives developed specifically for AAC production optimization. It has been developed and tested over the last five years by chemists with a lifetime experience in the AAC industry and has been successfully implemented in AAC plants around the world. The primary function is to act as a plasticizer enabling reduction of water, which is complemented with a stabilizing function, a homogenizing function and a catalyzing function. Chemical components in Poromix are blended in such way to achieve the following: reducing water in the mix, reducing consumption of cement and lime and, at the same time, improving the quality of products. Quality of products is measured by less cracks, stronger edges, less sticking and better distribution of the pores and homogeneity of the cake dry density and compressive strength.
In addition, Poromix-Alu is also offered, which acts as an aluminum activator by reducing water surface tension and degreasing particles of aluminum. This allows more stable reactivity from the same amount of aluminum, thereby optimizing the aluminum consumption.
Through the use of Poromix, water reduction of 4 to 8% can be achieved, depending on, amongst others, the density of the AAC product. The higher the base water-to-solids ratio the higher the reduction potential. The water reduction is possible thanks to reducing water surface tension (one of the functions of the additive) and as a result providing the same hydration to raw materials with less water.
Improving cake stability
At the same time other functions of the additive allow for reduction of cement and lime, improving cake stability and strength, as well as improving distribution of pores. From experience a reduction of 3 to 9% in consumption of other binders (mainly cement and lime) can be achieved.