Effect of an Aluminosilicate Disperse Additive on Behaviors of Autoclave Silicate Materials

Viktoriya Nelubova,Yuriy Vasilev,Valeria Strokova,Mugahed Amran,Roman Fediuk,Nikolai Vatin

doi:10.3390/buildings11060239

Abstract

In this research, a phase formation in CaO–SiO2–Al2O3–H2O binding system under hydrothermal conditions was studied. The novelty of this article lies in the quantitative full-profile X-ray diffraction (XRD) analysis used to determine kinetics of mineral formation in the binder system “lime–granite mineral modifier (GMM)”. The formation of a polymineral system is described in detail, as well as quantitative relationships between mineral composition of newly formed phases and the binding mixture ratios were determined. Phenomenological model of mineral formation in a “lime–GMM” system under hydrothermal conditions was proposed. The results obtained allow the demonstration of this binding system as a binder that is characterized by superposition of hydration and geopolymerization. The properties (strength, density, water absorption, porosity) of compressed autoclave-hardened materials with the addition of a granite modifier introduced instead of part of the sand as an aggregate have been studied. The maximum increase in strength (more than 50%) is observed at a modifier content of 15%. This is due to the formation of a rational composition of neoplasms, the compaction of the structure of the pressed products and the optimization of their pore space, which is confirmed by the data of X-ray diffraction analysis, scanning electron microscopy and the method of gas adsorption.

Highlights

The classical technology for the production of autoclave-hardened products provides for the use of lime and silica-containing raw materials as the main components, as a result of the interaction during which the formation of calcium hydrosilicates of various basicity [2] occurs in hydrothermal conditions at elevated pressure
To study phase formation in the CaO–SiO2 –Al2 O3 –H2 O binder system under hydrothermal conditions, prepared mixes of unslaked quicklime with granite mineral modifier (GMM) and plain tap water were exposed to hydrothermal conditions in an autoclave
The activated silica contained in the modifier contributes to the formation of low-base calcium–silicate hydrates of the tobermorite group, the main components of the mechanical strength properties of autoclaved materials

Summary

Introduction

Autoclave materials are considered effective construction materials due to the combination of satisfactory strength and high frost resistance while maintaining a given degree of thermal insulation [1]. The classical technology for the production of autoclave-hardened products provides for the use of lime and silica-containing raw materials as the main components, as a result of the interaction during which the formation of calcium hydrosilicates of various basicity [2] occurs in hydrothermal conditions at elevated pressure. The depletion of “pure” quartz raw materials (sands) [3,4], as well as the formation of significant volumes of technogenic waste [5,6], including waste from crushing rocks of various compositions, sets the task of expanding the spectrum of raw materials used [7]

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