Developing the composition of fine-grained concrete from the waste of the mining and processing enterprise

The object of this study is fine-grained concrete from the waste of mining and processing plants. These wastes are fine-grained dusty sands of polymineral composition. Their use as an aggregate for concrete is restrained by high water consumption, which does not make it possible to obtain sufficient strength for concrete. Therefore, the problem to be solved was the substantiation of the composition of fine-grained concrete from these wastes with mineral and chemical additives, which would ensure obtaining physical-mechanical and hydrophysical properties reasonable for the production of construction articles. The composition of fine-grained concrete from the waste at the Poltava Mining and Processing Plant and slag Portland cement in a ratio of 3:1 and additives of micro silica (15 % of the cement mass) and polycarboxylate superplasticizer (2 % of the cement mass) with W/C=0.5 was obtained. The compressive strength of this concrete reaches 40 MPa, which exceeds the strength of fine-grained concrete of a similar composition on natural fine-grained sand by 3 times. This is due to a greater degree of cement hydration, a greater number of formed hydration products, the presence of silica and quartz particles, a more uniform alternation of gel, silica particles, and crystal hydrates in the structure of cement stone. As a result, the structure contains a larger number of electro heterogeneous contacts between particles and grains that have negative (quartz, calcium hydro silicates) and positive (crystal hydrates of portlandite, hydro aluminates and calcium hydrosulfoaluminate) surface charges. This is what determines the achieved strength and water resistance of fine-grained concrete. The resulting composition of fine-grained concrete is recommended for the production of construction articles.