CONTROL OF STRUCTURE FORMATION PROCESSES OF SLAG-ALKALI CEMENTS ACTIVATED WITH SODIUM SILICATES
DOI:
https://doi.org/10.31650/2786-6696-2023-4-56-70Keywords:
Structure formation, setting time, alkaline activation, water-soluble high-modulus glass, intrinsic shrinkage deformations.Abstract
The article discusses approaches to the formation of the composition of slag-alkali cements when using high-modulus solution glass as an alkaline component, represented by a commercial product in the form of a liquid. The aim of this work was to study the effect of modifying additives, the silicate module of sodium hydrosilicates and technology modes on the processes of structure formation of artificial cement stone for effective control of setting time, intrinsic shrinkage deformations and achievement of high compressive strength (≥80 MPa at a standard age of 28 days and ≥ 20 MPa after 3 hours curing under normal conditions). As a result of the studies performed, a positive effect on the use of glycerin additives as part of a complex additive on the formation of the structure and properties of artificial stone was established. It is noted that the use of the studied modifying additives contributes to an increase in the degree of slag hydration, the formation, along with hydrosilicate compounds, of xerogel structures and celite-like compounds, which are deposited on the hydrosilicate-based matrix in the form of blocks-aggregates and increase the total volume of structure-forming compounds. A positive synergistic effect of using glycerin as an additional modifying component of the "trisodium phosphate + glycerin" complex additive for controlling the setting time in slag-alkali cements based on high-modulus solution glasses has been established. This made it possible to extend the time for the start of setting of slag-alkali cements when using solution high-modulus glasses from 3…5 min. up to values 26…83 min. Received cements with compressive strength after 3 hours 16.7...23.1 MPa, after 1 day 34.1...38.2 MPa, after 28 days 86.2...117.1 MPa with acceptable terms start of grasping. The heat release of such cements after 72 hours, despite their high activity, is only 150...180 J/h, which is 1.7...2 times less than that of fast-hardening Portland cement grade 600 and 2...2.4 alumina cement. Intrinsic shrinkage strains of compositions with modifying additives at the moment of stabilization were equal to 0.5…0.6 mm/m.
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