Cement compositions based on slag-Portland cement containing finely ground slag in its composition are considered. Fine-ground slag was obtained by grinding in a laboratory jet mill equipped with an automatic classifier. The upper limit of slag grinding was 20 microns. It was found that the introduction of 1-3% fine-ground slag into the composition of slag-Portland cement made it possible to increase the strength and structural characteristics of cement stone in the early stages of hardening. To ensure the stabilizing effect of finely ground slag particles in the cement matrix, cement compositions were sealed with water with the addition of a sulfonaphthalene-formaldehyde-based plasticizer in an amount of 0.5% of the cement content. In the course of research, it was found that the strength of samples containing finely ground slag and plasticizer increased by 50% at an early age of hardening (1-3 days), by 30% on average at 28 days of hardening, while the porosity of the samples decreased by 19% and 33%, respectively.

Keywords: fine-ground slag, ultrafine grinding, slag-Portland cement, plasticizer, cement stone, strength, porosity, normal density, setting time, degree of hydration