Physical foundations of variatropia recipe regulation and control of concrete properties with centrifugal seal

Levon Mailyan,Alina Demidova,Alla Smolyanichenko,Evgenii Shcherban,Sergei Stel’Makh,B Yazyev

doi:10.1051/e3sconf/202128103009

Abstract

The features and mechanisms of the processes occurring during concrete centrifugation are considered. It was found that a significant difference in the centrifugal and centripetal forces acting on the outer, middle and inner layers of the cross-section leads to significant differences in the structure and characteristics of the element layers. The possibility of regulating the variatropia and controlling the concrete properties during centrifugal seal by regulating the prescription factors is considered. The forms of various aggregates’ interaction with cement stone and the mixture components’ separation features during centrifugation are analyzed. Based on the analysis data, it is proposed to use a combination of various types aggregates and densities in centrifuged concrete. The main types of fibers are identified and the analysis of the effectiveness of their use is carried out. On the basis of the performed analysis, the most promising way of increasing the efficiency of fiber-concrete centrifuged elements was determined, namely, the combination of two or more types of fibers. The most expedient combinations of the aggregates and fibers’ types have been identified, which makes it possible to guarantee the directional movement of the components of the concrete mixture during centrifugation. In terms of the aggregate, this is the use of a large aggregate with a high density and a fine aggregate with a lower density, and in terms of fibers, it is a combination of steel and non-metallic fibers.

Highlights

Centrifugation is one of the widespread methods for manufacture of tubular concrete and reinforced concrete structures, providing the simultaneous execution of two technological operations - giving the configuration of the pipe loaded into the form of a concrete mixture as well as concrete mixture seal [1]
The essence of centrifugal molding and seal lies in the fact that when a mold rotates with a concrete mixture uniformly distributed in it around a fixed axis at a certain speed, centrifugal pressure arises, under the influence of which liquid with highly dispersed fractions suspended in it is squeezed out of the cement gel and at the same time larger particles approach solid
Steel-fiber concrete has a significant number of advantages over concrete with traditional reinforcement compressive strength increases by 10 ... 50%, axial tension by 10 ... 40%, impact strength 10-12 times, crack resistance - 3 times [14, 15]

Summary

Introduction

Centrifugation is one of the widespread methods for manufacture of tubular concrete and reinforced concrete structures, providing the simultaneous execution of two technological operations - giving the configuration of the pipe loaded into the form of a concrete mixture as well as concrete mixture seal [1].The essence of centrifugal molding and seal lies in the fact that when a mold rotates with a concrete mixture uniformly distributed in it around a fixed axis at a certain speed, centrifugal pressure arises, under the influence of which liquid with highly dispersed fractions suspended in it is squeezed out of the cement gel and at the same time larger particles approach solid. This will continue until there is an equilibrium between the forces promoting the mixture distribution in the mold and the structural resistance to the cement gel compression. With an increase in the rotation speed of the form, the liquid phase will begin to be squeezed out of the cement gel and will continue until the sealed mixture acquires the properties of a pseudo-solid [6,7,8,9]

Methods

Results

Discussion

Conclusion