Abstract
The chemical processes of Portland cement hydration enable the formation of concrete compressive strength. Under certain conditions, increasing the rate of cement hydration contributes to the improved strength of concrete at compression. This is especially true of the cellular concretes, specifically aerated concretes. The current work has investigated the influence of an integrated admixture that promotes gas formation in obtaining aerated concrete. The specified admixture consists of a mixture of hydrophobic surface-active substance – calcium oleate, perhydrol, and a nanomodifier, a mineral additive containing iron compounds. Feature of this research was the study into a simultaneous influence of hydrophobic surface-active substances, perhydrol, and mineral substances containing iron compounds, on a change in the strength of non-autoclave aerated concrete. The study was necessitated by the insufficient compressive strength of non-autoclave aerated concretes, whose manufacture employs aluminum powder or perhydrol as a gas-forming additive. Using aluminum powder does not provide for the homogeneity of its distribution throughout the volume of concrete; in addition, the cost of aluminum powder is rather high. It was established in the course of our study that the specified integrated admixture changes the character of strength formation in aerated concretes, specifically it increases its magnitude. It has been proven that in order to control the processes of cement hardening and to form the strength of artificial stone, which is obtained in the process of cement hydration, it is possible, in the manufacture of aerated concrete based on perhydrol, to use the admixtures-nanomodifiers containing compounds of iron, thereby improving the absolute magnitude of compressive strength of such concretes at the age of 28 days. The most effective is to use the nanomodifiers that contain a mixture of iron compounds, which leads to an increase in the strength of aerated concrete by up to 50 %.
Highlights
The construction structures of industrial buildings and facilities, located near thermal units, are affected by the environment, which changes the physical-mechanical properties of materials that these structures are made from, and, influences their durability
To determine the optimum composition of the nanomodifier containing iron compounds, we studied the strength of aerated concrete with the application of an iron-containing substance, which had a different ratio of carbonate to iron oxide (Fig. 6)
Our study has established the patterns in the influence exerted on the degree of porosity and compressive strength of aerated concrete by an integrated foam concentrate, which represents the dispersed system “mineral iron-containing nanomodifier – perhydrol ‒ calcium oleate”
Summary
The construction structures of industrial buildings and facilities, located near thermal units, are affected by the environment, which changes the physical-mechanical properties of materials that these structures are made from, and, influences their durability. This leads to the need to predict, when renovating buildings and facilities, appropriate measures to improve their service life by reducing the temperature effects from the environment. One of the effective materials for protection against thermal environmental influences is the light and porous concretes that have low thermal conductivity Such concretes do not demonstrate sufficient strength at compression. The issue of obtaining porous concretes, which have a sufficiently high strength, while using low-cost foam concentrates, is of significant scientific and practical interest, and resolving it is a relevant task
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