## 1 Introduction  
Local materials and industrial waste are widely used in the manufacture of foam concrete goods. They have an unstable chemical and mineral composition and dispersion, which impede the production of foam concrete with stable and improved quality indicators. The simplicity and availability of technology and local raw materials make foam concrete a relatively cheap and in-demand material for construction. The main shortcomings in the manufacture and use of non-autoclave-aerated concrete are as follows:  
1. the lack of reasonable recommendations that allow predicting the quality of goods by changing the mixer type, since the available recommendations are of a private nature with a low degree of generalization;the unreliability of equipment used due to defects in individual units (blades, hoses, valves, receivers, gearboxes, and so on);
* failure to meet the requirements for noise, vibration, beating, dust emission, electrical safety, ease of control, etc. ;
* heterogeneity of the resulting material in the terms of the quality of macrostructure, density, and strength (unacceptably high coefficients of variation). The mixing process is also influenced by the geometric parameters of mixer, the construction of mixing body, its location in the mixer bulk, the mixer shape and geometry, the ratio of the activator sizes to the mixer, and the shape and dimensions of mixer blades. In the petrochemical technology, sufficient experience has already been accumulated in modeling, calculation, design, and practical use of such mixing equipment. However, similar studies in the construction industry are insufficient and require additional consideration [1; 2; 3]. Analysis of existing mixer designs used for the production of building materials and in petrochemical engineering [1; 2] showed a wide variety of mixer and activator types. At the same time, the performance characteristics were approximately the same. In addition to the mixing energy applied to the fresh concrete (i.e., shearing during mixing), the shear history after mixing is also important. This applies especially to binder-rich concretes such as the different types of high-performance concrete (HPC). With this in mind, the shear rate is analyzed inside the drum of a concrete truck mixer. The objective is to better understand the effect of transport of fresh concrete, from the plant preparing mixture to the building site. The analysis reveals the effects of different drum loading bulk and its rotational speed. Moreover, the effects of yield stress and plastic viscosity are investigated. The studies show that the shear rate decreases in an exponential dependence with increasing drum loading bulk. It is also shown that, for a given drum speed, the shear rate decreases with increasing both the plastic viscosity and the yield stress [4]. Flexural tests were performed to investigate the influence of mixing time and mixer type on the performance. It can be concluded that mixing is beneficial for flat-type fibers in a fiber-reinforced concrete, but the performance of crimped or embossed fibers is equal. Moreover, longer mixing times (>10 min) in a pan mixer are detrimental to the performance, whereas the performance in a tilting drum mixer does not change even after a mixing time of 60 min [5; 6]. The optimization of a two-star planetary concrete mixer in terms of the wear resistance of blades was proposed, and a new design of the shape of mixing blades was shown and discussed. The authors proposed a new validation procedure of the mixing blades in the terms of wear resistance and efficiency, using three-dimensional (3D) optical scanners. This new wear measuring procedure is classifiable as a digital wear evaluation method, included in the field of digital tribology. The results demonstrate that the proposed new blade geometry improves the wear resistance, extends the useful life, and enhances the discharge operation [7; 8]. A coaxial mixer consisting of an anchor and Rushton turbine was considered in [9; 10].