Evaluation of the effectiveness of mineral additives in cement systems in the development of “core – shell” photocatalytic compositions

Abstract

Introduction. Creation of highly efficient photocatalysts for construction composites, which are characterized by increased activity and an extended spectral range of action, is a very important area of research. It is known that "core (substrate)shell (photocatalyst)" compositions, where mineral raw materials of various genesis can act as carriers, are one of the most effective types of photocatalytic additives for cement systems. It is worth noting that for integrated assessment of the substrate efficiency, we need to obtain information on the composition and properties of raw materials used among which its chemical activity and structure-forming role in cement systems are of paramount importance. The purposes of this study are (1) to establish the influence pattern of four types of mineral additives (silica fume, metakaolin, expanding sulfoaluminate modifier and microcalcite) on the structure formation processes of plasticized cement systems and (2) to identify the most effective modifiers for further use as mineral substrates in the photocatalytic compositions. Methods and materials. Specific surface area and granulometric composition of mineral modifiers were determined by the Kozeny-Karman and laser diffraction methods. The phase composition of mineral additives and modified cement systems were studied using X-ray diffraction phase analysis. Results and discussion. Features of mineralogical and granulometric compositions of mineral additives were revealed. It was determined that the use of individual and complex mineral additives based on silica fume, metakaolin and ESAM made it possible to directionally influence on content of the main phases of cement stone such as ettringite, portlandite, calcium hydrosilicates of different basicity. Conclusions. The increased chemical activity of these modifiers in cement systems, due to presence of reactive minerals in the structure, along with features of the granulometric composition (high dispersity and narrow particle size distribution), indicated the potential prospects for their use as mineral substrate in "core -shell" photocatalytic compositions.

Chemical activity score of siliceous rocks in development of self-cleaning cement material

“…It is known that 'core-shell' compositions obtained by precipitation of photocatalyst particles on dispersed carriers (substrates) are one of the effective types of photocatalytic additives for cement concretes. It is worth noting that mineral raw materials of various genesis can act as a substrate [15][16][17].…”

“…Foreign and domestic experience in obtaining 'core-shell' photocatalytic systems for cement materials shows that the type of photocatalytic agent carrier has a primary influence on the final parameters of the synthesized composite modifier [15][16][17]. In this regard, it is necessary to have data on the composition, structure parameters and physico-chemical properties of the mineral raw materials used, including its chemical activity, in order to qualitatively assess the effectiveness of the substrate.…”

Technological efficiency of mineral modifiers for cement materials with photocatalytic activity

“…It is aware that the efficient kinds of photocatalytic additives for cement materials are "core-shell" compositions synthesized by precipitation of photocatalyst particles on mineral substrates (dispersed carriers) [16][17][18][19].…”

“…Foreign and domestic experience in obtaining "core-shell" photocatalytic systems for cement materials shows that the type of photocatalytic agent carrier has a primary influence on the final parameters of the synthesized composite modifier [16][17][18][19]. In this regard, it is necessary to have data on the composition, structure parameters and physico-chemical characteristics of the mineral raw materials used in order to qualitatively assess the effectiveness of the substrate.…”