The aim of this study was to determine the effect of finely ground filler on the properties of slag-alkali binder based on blast furnace slag. An aqueous solution of sodium silicate and caustic soda (aqueous solution of NaOH) was used as a hardening activator with an alkali modulus (weight ratio SiO2/Na2O) equal to 1.0 and 0.5. The results showed that the introduction of Reftinskaya GRES fly ash into the binder instead of ground blast furnace granulated slag causes an increase in the initial setting time, but does not affect the final setting time. No cracking was detected during hardening in mixtures containing fly ash, provided that a complex based on sodium silicate and an aqueous solution of NaOH was used as a hardening activator. The introduction of alkali into the sodium silicate solution helps to reduce the silicate modulus (the mass ratio of SiO2/Na2O) and reduce the formation of shrinkage microcracks due to the formation of a homogeneous structure and the formation of fly ash and the formation of sodium hydroaluminosilicate (H-A-S-N).

Keywords: cement paste, ground granulated slag, fly ash, hardening activator, setting time, shrinkage, microcracks

The aim of the study was to determine the effect of the amount of alkaline hardening activator on the geopolymer binder consisting of ground blast furnace slag and fly ash. Ground blast furnace slag with fly ash was activated with sodium silicate (SN) at different contents of alkali solution (A). The results showed that an increase in the alkali activator content (SN:A = 5%:3% → 15%:4%) promotes an increase in the strength of concrete over the entire time interval of monitoring the strength gain. The addition of fly ash affected an increase in the compressive strength of concrete samples from 16 to 18% relative to the compositions without fly ash. Micro cracking is manifested in the compositions of geopolymer concretes without fly ash, activated by a sodium silicate solution at a higher silicate modulus. The reduction of the silicate modulus CH led to less microcrack formation and a more uniform structure, and the introduction of fly ash into the concrete mixture helps to eliminate internal stresses and the formation of microcracks on the surface of concrete samples.

Keywords: by-products, blast furnace slag, alkaline hardening activators, fillers, performance properties, strength, water absorption, development driver

Slag-alkali binder (SAB) is obtained by polymerization of granulated blast-furnace slag (aluminosilicate component) ground in a ball mill with an alkali activator, resulting in an environmentally friendly hydraulic polymer binder. Slag-alkali concrete (SAB) based on SAB has become an alternative to traditional concrete based on portland cement (PTC). Reinforcement bars in combination with SAB make it possible to obtain concrete structures with high adhesion properties to reinforcement compared to concrete based on portland cement. However, due to differences in the production process of SAB, there are obvious differences in technical properties, including adhesion characteristics. However, proper standardization is needed for its production and operational testing to limit contradictory results in the laboratory and on the construction site.

Keywords: metallurgical waste, granulated slag, crushing, chemical activation, reinforcement, adhesion, strength

Concrete paving slabs for road construction are made from mixtures consisting of hydraulic binder, fine and coarse aggregates and water. The prepared mixture of a given humidity is subjected to vibration molding under the following technological conditions: process duration 5–10 seconds, vibration frequency 30–50 Hz and pressure 70–80 kg/cm2. Hardening of freshly molded samples is carried out in a heat and humidity treatment chamber. It has been established that it is possible to replace natural coarse aggregate with fractionated scrap concrete. The compressive strength of concrete with aggregate based on recycled crushed stone is 300 - 400 kg/cm2, water absorption 4.8 - 6.2%, frost resistance F2 200 - 300. The proposed technology allows solving both economic and environmental issues for regions with large amounts of concrete scrap at temporary industrial waste storage sites.

Keywords: concrete mixture, vibroforming, modifiers, filler, waste, concrete scrap, strength

The influence of blast furnace ground granulated slag on the kinetics of strength gain of concrete prepared with a composite binder was revealed. The composite binder contained Portland cement in amounts of 70, 60 and 50%, and the rest was ground granulated slag. It has been established that at the early stage of strength development, concretes made with a composite binder have a strength lower than concrete prepared with Portland cement by 10-24%. However, at the age of 28 days, the strength of concrete using a composite binder corresponds to the strength of concrete using Portland cement. Using polycorboxylate hyperplasticizers, it was possible to obtain concrete with a W/C ratio of 0.25-0.35, which made it possible to obtain high early strength exceeding control compositions by 10-20%.

Keywords: portland cement, grn slag, grinding, composite binder, kinetics of strength gain, hyperplasticizer, kinetics of strength gain

The physicomechanical properties of paving slabs produced by vibropressing technology are determined. The compositions of fine-grained concrete using quartz fine-grained sands and very fine sands are proposed. The obtained results confirmed the possibility and effectiveness of the use of substandard fine-grained raw materials of the local raw material base, which ensure a reduction in the cost of production.

Keywords: fine-grained concrete, vibrocompression, raw material base, substandard sands, ground sand, active rheological matrix

Porous concrete is a new type of concrete with high permeability of water flows. It is advisable to use this type of concrete in road construction for the device filtration zones. This will allow to remove water from the carriageway, especially in places where there is no storm sewer. Infiltration of water flows through concrete pavement coatings contributes to their rapid removal from the surface, reducing slipperiness and water planning. The use of macroporous concrete will minimize flooding of car parks and roads. The results of the study confirm that permeable concrete surfaces function stably over time and are not silted with sand and soil.

Keywords: porous concrete, permeable surface, filtration, storm sewage, water

The use of ultrathin sand as the main raw material in the production of concrete made by semi-dry molding is relevant for many regions of Russia due to the lack of sand with a high modulus of grain size and solid stone. The article presents the results of the analysis of the possible use of sands with a modulus of particle size Mcr = 0.8-1.4 in pressed small-sized concrete paving products for sidewalks. Replacing ordinary sand up to 80% with fine-grained does not reduce strength and performance properties. The transition to fine-grained and silty sands reduces the cost of production.

Keywords: concrete, semi-dry pressing, knitting, ultra-fine sand, hyper-plasticizer, strength

Investigations were conducted to assess the corrosion resistance of stabilized sandy loam soil with ground granulated slags in organic media: mineral oil, gasoline and diesel fuel. A model is proposed for an accelerated study of the corrosion resistance of concretes and other building materials under the conditions of the dynamic effect of the medium under investigation on the test material. The obtained results of X-ray phase analysis of samples and electron microscopic studies suggest that as a result of hydration of minerals of ground slag and ground, low-base CSH (B) hydrosilicates are formed, the sizes of new formations and inclusions on ETF slag are less than on CMP slag.

Keywords: ground granulated slags, low-basic formations, corrosion resistance, slag-alkali binder, oil, porosity, dynamic model