Topological calculation of key parameters of fibre for production of foam concrete based on cement-free nanostructured binder

Fiber reinforcement is the process of introduction of fibers of different origins into binding system to enhance strength, stress-strain behavior of products and structures. Maximal effect of reinforcing process is possible when optimal parameters (length and consumption of fibre) are determined. Moreover one need to consider particle-size composition and hardening process of binding system. In this paper the critical length of natural and sinthesized fibres as well as minimally required content in cellular systems is calculated with the mathematical apparatus of structural topology. As an example the foam concrete based on cement-free nanostructured binder with basalt fibre and microreinforcing constructional polymeric fibre is studied. Fiber diameter, refined with microstructure analysis, accomplished by SEM-microscopy and experimentally determined packing density in loose and compact state are applied as input parameters. Measurement of the fibre topological characteristics with acceptable is accomplished according to material porosity and pore size. So the minimal effec- tive fibre length taking into account homogeneous distribution in bulk of composite matrix is less of 1 mm; minimal fibre consumption is 0,2-0,5 (by wt. %). Irrational optimization leads to unreasonable cost growth of final materials as well as formation of balling inclusions that negatively affects on final performance of composite.