"Вестник МГСУ"

Subject: applying mineral microfillers based on technogenic waste of non-ferrous metallurgy together with nano silica in the technology of cast and self-compacting concrete is the subject of the paper. The results of the previous experiments proved the effectiveness of the use of ground copper slag in the technology of cast concrete mixtures. However, there are no research results on the combined work of the microfiller and nanoparticles in plastic concrete mixtures. Research objectives: determining the optimal range of the use of nano silica in cast concrete mixtures with copper slag filler from the viewpoint of conservation of plasticity of the concrete mixture and increase of the concrete strength. Materials and methods: plasticity of the concrete mixture was determined according to spread of a small cone on the shaking table by the method developed in NRU MGSU. The strength of concrete samples was checked according to GOST 10180-2012. Statistical processing of the obtained results was carried out by the least square method. Results: plots showing dependence of plasticity of the concrete mixture and strength of cast concrete with ground copper slag on the dosage of nanoparticles and also the influence of the dosage of superplasticizer on the indicated properties at high values of the content of nano silica were obtained. Regression equations for all specified dependencies were derived. Conclusions: it is established that the introduction of nano silica in a dosage of 0.1…0.5 % of cement weight positively affects the concrete strength when used in conjunction with copper slag and superplasticizer. The developed compositions of cast fine-grained concrete mixtures can be used in high-density reinforcement concrete structures with strict requirements for size of fillers and plasticity of the concrete mixture.

Subject: applying mineral microfillers on the basis of technogenic wastes of non-ferrous metallurgy in the technology of cast and self-compacting concrete. The results of experiments of scientists from Russia, Kazakhstan, Poland and India show that copper smelting granulated slag can be used when grinding construction cements as a mineral additive up to 30 % without significantly reducing activity of the cements. However, there are no results of a comprehensive study of influence of the slag on plastic concrete mixtures. Research objectives: establishment of mathematical relationship of the influence of copper slag on the compressive strength and density of concrete after 28 days of hardening in normal conditions using the method of mathematical design of experiments; statistical processing of the results and verification of adequacy of the developed model. Materials and methods: mathematical experimental design was carried out as a full 4-factor experiment using rotatable central composite design. The mathematical model is selected in the form of a polynomial of the second degree using four factors of the response function. Results: 4-factor mathematical model of concrete strength and density after curing is created, regression equation is derived for dependence of the 28-days strength function and density on concentration of the cement stone, true water-cement ratio, dosage of fine copper slag and superplasticizer on the basis of ether polycarboxylates. Statistical processing of the results of mathematical design of experiments is carried out, estimate of adequacy of the constructed mathematical model is obtained. Conclusions: it is established that introduction of copper smelting slag in the range of 30…50 % by weight of cement positively affects the strength of concrete when used together with the superplasticizer. Increasing the dosage of superplasticizer in excess of 0.16 % of the dry component leads to a decrease in the strength of cast concrete. The developed compositions of cast fine-grained concrete mixtures can be used in high-density reinforcement concrete structures with strict requirements for size of fillers and plasticity of mixture.