: 12-20
Lviv Polytechnic National University
Research and Production Company "Halychyna"
Lviv Polytechnic National University
Lviv Polytechnic National University

Grinding aids (GAs) for cement clinker milling is used to reduce the energy required to achieve a given degree of cement powder dispersion. Some products in the GA, commonly referred to as performance enhancers, have a positive effect on the hydration of cement, improving the strength of the concrete. At grinding of materials simultaneously occur two opposite processes: the destruction of particles by external force and the aggregation of particles, which can be arbitrary, as well as due to external compressive forces. In finely divided mills characterized by a large specific surface of the powder, the influence of the grinding medium, in particular, surfactants (SACs – surface active compounds), is significant. When deformation in the surface layer of a solid body there are wedge-shaped microcracks, which, in the absence of loading, have the ability to close. The surfactants that are adsorbed on the solid surface can fill these microcracks and resist their closure. Adsorption of surfactants and at the same time reducing the surface energy lead to an increase in the size of cracks and a decrease in the magnitude of stresses in which microcracks undergo development to the state of destroy cracks.

The kinetic regularities of cement clinker grinding, using industrial grinding intensifiers - propylene glycol, "RENA-CEMERIN-01" and "RENA-CEMERIN-02" are investigated. During grinding, measurements of the specific surface of the obtained samples of cement and their dispersion were carried out. The efficiency of grinding intensifiers is established on the basis of comparison of the rates of grinding constants for the initial sections of the kinetic curves. The coefficients of crushing ability were found for propylene glycol, which for the grinding intensifier "RENA-Cemerin-02" (active substance 60%) was the largest and was 1.24 with a grinding time of 20 minutes. It has also been shown that this grinding aid  provides three times more clinker milling and an average of 10% higher specific surface of cement than with propylene glycol. Such grinding aid as trade marks "RENA-Tsemerin-02" containing the active substance at 60% was showing greater specific surface area of cement on average by 10% than when using propylene glycol for grinding time 60-180 minutes.

It has been found that the reletionship between the specific surface area (Y) and the grinding fraction (x) of less than 0.08 mm is well correlated with the polynomial of the second degree. Within the range of 45-95% for a grinding fraction of less than 0.08 mm, these reletionships are described by the following formulas: for GA "RENA-CEMERIN-01 - Y = 1.2218x2 - 92.75x + 3435.6 (R² = 0,9749) and for the AP "RENA-CEMERIN-02 - Y = 1,2125x2-88,44x + 3312,8 (R² = 0,9898). The coefficients of these regressions are close to each other for the two new GAs, which may indicate the similarity of the granulometric distribution.

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