No abstract

The paper scrutinizes the application of an ultradispersed filler from activated quartz waste as a modifier of cement stone and resulting physicomechanical characteristics of the latter. The deliverables justify the addition of the ultradispersed filler to cement stone in production of cement concrete. The physicomechanical characteristics of quartz-cement stone after dry and wet activation are given. Goal: the goal of the present work is to study the physicomechanical properties of the cement stone modified by ultradispersed quartz filler. Methodology: mechanical milling is used to get ultrafine particles. Research results: the research establishes that the effective ratio of ultradispersed activated quartz to cement is 30:70. The application of the ultrafine filler based on activated quartz waste allows increasing the density by 7%, strength by 35% and lowering the heat conductivity by 16%. Practical use of results: the work proposes a method for producing cement stone with augmented physicomechanical properties using quartz waste in the amount of 30% in total cement volume. Value: the work scientifically justifies the possibility to produce cement stone under hydraulic activation with denser structure with the major volumetric fraction of the filler represented by quartz waste particles with dimensions less than 20 μm.

The article presents a technology for producing concrete using the waste of wood processing plants as the concrete filler. The waste was activated by mechanical, hydromechanical and hydromechanochemical technologies in a centrifugal disk installation. The established optimal ratio of sand to the waste (activated mixture) is 70:30%. The accepted fraction of the activated mixture is 10 wt% (of the mass of cement). The tests confirmed the reduction in the average density of the cement stone, while preserving its strength; the thermophysical properties of the stone increase.

The review is based on the results of operation of the total ozone (TO) monitoring system in Russia and neighboring countries that functions in the operational mode at the Central Aerological Observatory. The monitoring system uses data from the national network equipped with M-124 filter ozonometers being under the methodological supervision of the Main Geophysical Observatory. The quality of the functioning of the entire system is operationally controlled using the OMI satellite equipment observations (NASA, USA). Basic TO observation data are generalized for each month of the fourth quarter of 2020, for the fourth quarter, and for the whole year. Data of routine observations of surface ozone in the Moscow region are also presented.

Subject of research: the article considers foamconcrete on quartz cement binder, the mass introduction of quartz raw materials in construction can be considered practically achievable and economically profitable. Purpose of research: the technology of foam concrete on quartz-cement binder is proposed by introducing an ultrafine filler (nanomodifier) from activated quartz waste into the binder, reduces cement consumption by 10 % and improves its physical and mechanical properties. Methods and objects of research: the nanomodifier was obtained with mechanical and mechanohydraulic activation, the proposed filler activation technologies will improve the structure of cement stone forming foamconcrete pore-forming partitions by increasing the packing density and chemical activity of nanoscale particles in the processes of hydrate compounds phase formation. Main results of research: the proposed technology of heat-insulating foamconcrete on quartzcement binder allows you to create a pore structure with a diameter of 52 microns at a density of 500 kg/m3 foamconcrete samples and a total porosity of 6575 %, and will also increase the strength characteristics of foamconcrete to 7.713.8 % due to discrete reinforcement with quartz waste (nanomodifier) of pore-forming partitions.