Розробка рецептур геобетонів на основі активованого шламу каменеобробки для зменшення споживання природних ресурсів

This study investigates concrete mixtures modified by partial or complete replacement of cement and sand with granite and gabbro sludge from stone-processing plants, activated with a 12M NaOH solution to improve their mechanical properties and microstructure. The task addressed relates to the excessive accumulation of sludge waste from the stone-processing industry, which pollutes the environment and predetermines the need to reduce the consumption of natural resources (cement and sand) in concrete production. This production is accompanied by high CO2 emissions and significant costs. All these factors necessitate designing environmentally friendly and economically viable construction materials. The study investigated the effect of replacing cement (0–100%) and sand (0–100%) with a mixture of granite and gabbro sludge on compressive strength and ultrasonic pulse velocity after 7, 14, and 28 days of curing. Replacing up to 30% of sand provides a compressive strength of 45–50 MPa while replacing up to 20% of cement provides 30–32 MPa on day 28, meeting structural requirements (>10 MPa). The ultrasonic velocity (4200–4300 m/s at 30% sand replacement and 3800–4000 m/s at 20% cement replacement) indicates the preservation of a dense structure. Distinguishing features of the results are attributed to the combination of granite and gabbro sludge activated with NaOH that produces a microfiller effect and enables pozzolanic activity. This makes it possible to reduce sand consumption by 30% and cement by 20% without a significant loss of strength. Unlike conventional mixtures or solutions using only one type of sludge, strength reduction proceeds more slowly due to fewer microcracks. The results are suitable for producing environmentally friendly concrete for road and residential construction under moderately aggressive environmental conditions. The optimal replacement (30% sand or 20% cement) is effective under both laboratory and industrial conditions, provided that the sludge has a homogeneous composition and is activated with NaOH