"Вестник МГСУ"

Subject: we consider the problem of supplying the construction industry, in particular underground construction, with mineral binder for diluted aqueous suspensions that meet the requirements for reinforcement of low-strength sand and clastic soils by injections into the reinforced soil mass. Research objectives: substantiating possibility of using amorphous biosilica in combination with carbide sludge, whose particles size does not exceed 10 mm on average, as a binder for aqueous suspensions being injected. Materials and methods: as raw materials we used: common construction hydrated lime from “Stroimaterialy” JSC, Belgorod, hydrated lime in the form of carbide sludge from the dumps of Protvino plant (carbide sludge, hereafter), active mineral admixture biosilica from the group of companies “DIAMIX” and a plasticizer Sika viscocrete 5 new. Test methods are in accordance with applicable standards. To obtain samples of impregnated soils, a specially developed technique was used in the form of a unidirectional model. Results: properties of the composite binder prepared with different compositions are presented. The optimal component ratios are determined. The following properties of aqueous suspensions are studied: conditional viscosity, sedimentation and penetrating ability. Conditional viscosity is no more than 40 sec on average. Sedimentation does not exceed 1.2 %. Soil-concrete obtained by injection of a dilute aqueous suspension based on this composite binder has a compressive strength in the range from 4.44 to 12.5 MPa. Conclusions: utilization of finely dispersed composite mineral binder, which is based on interaction of amorphous silica with calcium hydroxide, as a binder for high penetration aqueous suspensions has been substantiated. This binder is not inferior to foreign analogues in terms of its strength and technological parameters and can be used for reinforcement of loose and low-strength soils. In case of using carbide sludge, the ecological and environment protection problems are being solved since it is a waste product in production of acetylene.

In the last decades in a number of countries burned clays have been used as a pozzolanic additives to the concrete, which is connected with their universal distribution and cost savings due to reduction of long-distance transportation of the additives. The haydite dust is the co-product of the haydite gravel. At every enterprise of haydite gravel about 7-8 tons of haydite dust are daily formed. The haydite dust represents thermally activated clay. Its structure includes a certain amount of non-dehydrated clay and dehydrated clay minerals with crystal lattices of different levels of defects. Previously the authors described the compositions of cost-effective composite gypsum binding materials produced with complex mineral additive, including lime, a ground haudite dust and the superplasticizer possessing the durability at compression up to 27 MPa and coefficient of softening up to 0,78. In this paper the authors investigated the composition and structure of artificial stone on the basis of the developed composite gypsum binder. As a basic binder building plaster is used. In the research work the X-ray phase analysis, the differential thermal analysis, electron microscopy and the standard methods of research of concrete porosity were used. The introduction in composition of gypsum binder with a complex mineral additive allows to receive an artificial stone with more dense and finegrained structure, durability and water resistance in comparison with original binder without any additive. The content of ettringite in the course of hardening does not increase. The formation of low based low-main hydrosilicates of the calcium filling steam structure of a gypsum stone, forming additional contacts between the gypsum crystals, raising stone water resistance is established.

The article covers the research into the structure and technology of building composites produced on the basis of nano-portlandite and aluminosilicate contact condensation systems of hardening. The authors have proven that the use of non-equilibrium portlandite crystals synthesized on the basis of a specialized technology and combined with nano-scale, microscale particles of the aluminosilicate component can lead to the production of composites that demonstrate acceptable strength (at least, 10 MPa) immediately after compaction absent of any heat and moisture treatment, if optimal mixture compositions are compacted using compression methods.Principal process-related procedures are provided in the article. Under certain circumstances, composites of this type can replace clinker binders to improve the structure efficiency. Research and development solutions are based on the principles of the sol-gel technology; the nanotechnology is implemented according to the “bottom-up” pattern in terms of synthesis of portlandite crystals, and the “top - down” approach is employed in terms of mechanical and chemical activation of aluminosilicate components used as fillers. The research can be considered as the basis for development of process flow diagrams and provision of consultations concerning the manufacturing of advanced building products.

Different aerated mortars are used for pargeting of walls made of aerated concrete. Though the regulatory documents don’t specify the dependence of plaster density from the density grade of gas-concrete blocks. In case of facing of gas-concrete blocks with the grade D500 using plaster mortars with the density 1400…1600 km/m3 there occurs a dismatch in the values of thermal insulation and vapor permeability of the plaster and base. The authors suggest using dry mortars for finishing of gas-concrete block of the grades D500 и D600, which allow obtaining facing thermal insulating coatings. The efficiency of using four different high-porous additives in the lime dry mortar was compared. They were: hollow glass microspheres, aluminosilicate ash microspheres, expanded vermiculite sand, expanded pearlitic sand. The high efficiency of hollow glass microspheres in heat insulating finishing mortars compared to other fillers is proved.

The authors studied the effect of the process parameters (pH, concentration of Ca2+) on precipitation of humic acids contained in the filtrate of solid waste in the process of its decontamination using lime. The content of contaminants in the filtrate was monitored through the employment of well-known methodologies using methods of optical molecular and atomic spectroscopy; pH values were monitored through the employment of the potentiometric method. In some cases, chemical oxygen demand was measured to identify changes of the content of organic substances in the solution. Concentration of humic substances was identified by measuring the absorption spectra in the UV and in the visible range and by applying the calibration curve. Samples of humic and fulvic acids produced by Ecoanalitika Open Joint Stock Company were used for benchmarking purposes.The optimal amount of lime milk for the purpose of precipitation of humic substances in the filtrate is equal to 24 g/l. It is proven that any further increase of the lime milk flow is limited by the increase of the residual calcium concentration in the purified solution. Consumption of lime milk in the course of clarification of filtrates may be reduced by sharing it with calcium salts. By adding 10% of calcium chloride to the lime milk content, lime milk consumption may be reduced by 50%.

The subject matter of the article is the construction industry in the years of pre-Mongolian Rus. The complexity and diversity of the construction process reflect some peculiarities of the social life in ancient Rus. Therefore, the study of the construction industry reveals particular technological advancements as well as the professional and social organization of crafts in ancient Rus. In the article, the organization of the building process is considered as an integrated process.
A considerable amount of information can be obtained from ancient sources, such as monuments, although they do not constitute any accurate evidence of the construction process. We may identify the number of the so-called "artels" (construction gangs), as well as trace their routes from one construction centre to another. By the commencement of the Mongolian invasion, construction gangs had already established close connections with the prince in power, and their routes were always determined by dynastic relationships of princes. Their work was strongly influenced by Byzantine and West European countries. Therefore, the analysis of the whole construction industry is a vital constituent of the study of the history and culture of ancient Russians.