Mathematical Modeling and Experimental Substantiation of the Gas Release Process in the Production of Non-Autoclaved Aerated Concrete

Abstract

The widespread use of aerated concrete in construction has led to the emergence of many types and compositions. However, additional research should fill theoretical gaps in the phenomenon of gas release during the formation of the structure of aerated concrete. Based on theoretical analysis and experimental studies, the article proposes a mathematical model of the swelling process based on the physicochemical laws of convection and molecular diffusion of hydrogen from a mixture and the conditions of swelling, precipitation, and stabilization of the mixture. An improved method for the manufacture of aerated concrete is proposed, which consists of introducing cement pre-hydrated for 20–30 min into the composition of the aerated concrete mixture and providing improved gas-holding capacity and increased swelling of the mixture, reducing the average density of aerated concrete up to 29% and improving heat-shielding properties up to 31%. At the same time, the small dynamics of a decrease in the strength properties of aerated concrete were observed, which is confirmed by an increased structural quality factor (CSQ) of up to 13%. As a result, aerated concrete has been obtained that meets the requirements of environmental friendliness and has improved mechanical and physical characteristics. Economic efficiency is to reduce the cost of production of aerated concrete and construction in general by about 15%.

Analytical Review of Geopolymer Concrete: Retrospective and Current Issues

“…(7) An assessment was made of the potential reduction in greenhouse gas emissions from the production of geopolymer concrete compared to the production of OPC. (8) The inclusion of nanomodifiers, such as graphene oxide, in the composition of geopolymer concretes reduces the hardening time of the composition and increases the stability of the microstructure of the material, improving its physical and mechanical properties and positively affecting durability. (9) The most promising areas for further research of geopolymer concretes are the search for new types of aluminosilicate binders and activators; the analysis of the economic and environmental efficiency of geopolymer concretes; the development of methods for the optimal selection of compositions; the analysis of the effect of nanomodification of the composition of geopolymer concrete on the characteristics of the finished material; the search for new technologies that allow more efficient and productive 3D printing using geopolymer concretes; the search for new technologies to improve the properties of geopolymer concretes by nanomodifying the composition with graphene oxide and the search for alternative, more effective nanomodifiers; the search for technologies that can reduce the toxicity of certain types of geopolymer concretes for fresh reservoirs and humans; the search for new technologies and replacement methods concrete on OPC with geopolymer concrete and the search for new methods for monitoring the state of structures using self-sensing concrete.…”

“…This is a record value that exceeded the values of previous years (419 ppm for 2021 and 417 ppm for 2020) [ 6 ]. Several studies have been devoted to solving a similar problem—the disposal of agricultural, industrial waste, fuel, and energy complex in concrete, but at the same time in concrete based on cement [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. At the same time, it should be noted that geopolymer concretes are even more promising, environmentally friendly, and economical due to the absence of clinker binders in them and the use of more environmentally friendly cheap components in their composition, which can significantly approach the implementation of the global environmental agenda.…”

Influence of Recipe Factors on the Structure and Properties of Non-Autoclaved Aerated Concrete of Increased Strength

“…The thermal conductivity of samples of non-autoclaved aerated concrete was determined on the device ITP-MG4 LLC SKB Stroypribor (Chelyabinsk, Russia) in accordance with the requirements of GOST 7076 "Building materials and products. Method of determination of steady-state thermal conductivity and thermal resistance" on sample plates 100 × 100 × 20 mm in size [57]. "The principle of operation of the device is based on creating a stationary heat flux passing through a flat sample of a certain thickness and directed perpendicular to the front faces of the sample, measuring the sample thickness, heat flux density and temperature of opposite front faces" (Figure 3).…”

Numerical Simulation of Heat Transfer and Spread of Virus Particles in the Car Interior

“…New numerical approaches for flow and engineering problems are discussed in [37,38]. The papers [39][40][41][42][43][44][45] present the results of a CFD analysis of thermal and hydrodynamic characteristics in various vehicles and consider optimization issues for various cab configurations and geometries. The results of these works were obtained based on the numerical solution mainly by the RANS Navier-Stokes equations, without taking into account air humidity and the particle motion model.…”