Increasing the performances of low permeable cement composites

Abstract

Introduction. The purpose of the article is to expand the range of compositions for special structures, which will allow them to be operated in extreme conditions. To achieve this goal, a number of tasks have been solved containing ways to improve the efficiency of composites, incl. low-permeability ones.
 
 Materials and methods. The research methodology includes a system of transdisciplinary approaches that evaluate the composite as a complex system, taking into account the provisions of geomimetics, such as the law of similarity, the law of affinity of structures, technogenic metasomatism, and micromechanics of composite media.
 
 Results. A wide range of cement concretes has been created for unique objects: low-permeability (for protective objects, reservoirs and hydraulic structures). The developed composites have the following performance characteristics (the results for the control sample are given in parentheses): water absorption by weight — 2.5 % (6.1 %), waterproof grade — W14 (W10), air permeability — 0.0253 cm3/s (0.0565 cm3/s), vapor permeability — 0.0021 mg/(m-h-Pa) (0.0030 mg/(m-h-Pa)), effective diffusion coefficient — 1.34 · 10–4 cm2/s (1.56 · 10–4 cm2/s).
 
 Conclusions. The similarity in the work of the components of different composite binders, incl. During the two-stage hydration of clinker minerals, in particular, in the first phase, the formation of low-density compounds of different phases occurs, and in the second phase, the binding of calcium hydroxide to low-basic crystalline hydrates occurs. The increase in the activity of the composite binder is due to the synergistic effect of a number of reasons: amorphous silica-containing components bind Ca(OH)2, released during the hydration of clinker minerals, in the second generation CSH(I); limestone particles clog the pores, compacting the structure; and fly ash microspheres are centers of crystallization of new growths.