Mineralogical Aspects of Durable Geocement Matrix Formation - Role of Alkali

Abstract

Less than half a century ago just an idea of presence of free alkalis in a ceramic matrix was considered by ordinary Portland cement people as an absurd one and this was a basic postulate accepted in chemistry of cements. In 1957 a scientist from Ukraine (USSR) Viktor Glukhovsky put forward an assumption which was taken as a base for development and bringing into practice of construction a principally new class of cementitious materials which first appeared in the field under a name of alkaline (now also known under a general name of alkali-activated) cementitious materials. A validity of these ideas was confirmed by more than 50 years of evolutional development and vast experience collected on practical use of new materials in different applications. The paper covers theoretical views on role played by alkali in the formation of an alkali-activated cement matrix with high durability. Examples of compositional build-up of the alkali-activated cementitious materials vs. quantity of added alkali and type of aluminosilicate component are reported together with results of 50-year experience obtained from observation of concrete structures made from these cements.

Investigation of the influence of organomineral additives on the colloid-chemical properties of geocement dispersion

“…-the quality of the binder, which is characterized by viscosity, surface tension, the presence of gels and microgels, particle size, colloidal stability and adhesion strength. The consistency of the binder itself and the strength, hardness and durability of materials based on it depend on the type and composition of these indicators [1][2][3][4][5][6][7][8][9][10][11][12]; -dependence of the surface tension of uncured mineral binders on the nature of the solvent. With an increase in the concentration of solvents, the surface tension of unconfined binders decreases, and the greater, the less the surface tension of the solvents [25][26][27].…”

“…In general, the main properties of the binders themselves are considered: the processes of structure formation, strength, frost resistance, etc. [1][2][3][4][5][6][7][8][9][10][11][12]. Occasionally, publications aimed at studying special properties (heat resistance, fire resistance, corrosion resistance, etc.)…”

Nano-Structured Alkaline Aluminosilicate Binder by Carbonate Mineral Addition

“…There are many publications devoted to the problems of alkaline activation of metakaolin, a mixture of metakaolin with ash in the presence of solutions of alkalis in which the action of alkaline ions is noted not only in the stage of metakaolin destruction, but also in the final stage of the formation of the condensed structure [1]. In [2][3][4][5][6] shows data on the interaction of mixtures of kaolin and feldspar, activated liquid glass, and it is shown that polycondensation is a three-step process: dissolving kaolin and feldspars to form a gel, condensing the gel and polycondensation it into three-dimensional structures Al and Si, in which Na + or K + compensate for the electric charge of aluminum. In the course of polycondensation, water acts as a solvent and as a reaction agent.…”