Co-Doped Magnesium Oxychloride Composites with Unique Flexural Strength for Construction Use.

Anna-Marie Lauermannová,Zbyšek Pavlík,Adam Pivák,Julie Slámová,Milena Pavlíková,Šimon Marušiak,Michal Lojka,Ivana Faltysová,Ondřej Jankovský,Martina Záleská

doi:10.3390/ma15020604

Abstract

In this study, the combined effect of graphene oxide (GO) and oxidized multi-walled carbon nanotubes (OMWCNTs) on material properties of the magnesium oxychloride (MOC) phase 5 was analyzed. The selected carbon-based nanoadditives were used in small content in order to obtain higher values of mechanical parameters and higher water resistance while maintaining acceptable price of the final composites. Two sets of samples containing either 0.1 wt. % or 0.2 wt. % of both nanoadditives were prepared, in addition to a set of reference samples without additives. Samples were characterized by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and energy dispersive spectroscopy, which were used to obtain the basic information on the phase and chemical composition, as well as the microstructure and morphology. Basic macro- and micro-structural parameters were studied in order to determine the effect of the nanoadditives on the open porosity, bulk and specific density. In addition, the mechanical, hygric and thermal parameters of the prepared nano-doped composites were acquired and compared to the reference sample. An enhancement of all the mentioned types of parameters was observed. This can be assigned to the drop in porosity when GO and OMWCNTs were used. This research shows a pathway of increasing the water resistance of MOC-based composites, which is an important step in the development of the new generation of construction materials.

Highlights

The recent advances in the research of the magnesium oxychloride cement (MOC) [1,2]show a promising direction in the field of alternative construction materials
The properties of MOC are influenced by its ability to absorb CO2 from the atmosphere [20,21] which results in the formation of magnesium carbonate phases on the surface of MOC
Samples were marked as MOC-REF, MOC-GOOMWCNT-0.1 and MOC-GOOMWCNT-0.2

Summary

Introduction

The recent advances in the research of the magnesium oxychloride cement (MOC) [1,2]show a promising direction in the field of alternative construction materials. Its ability to bond a wide range of additives makes it possible to enhance its properties by using various fillers and to create materials with very specific mechanical, physical, chemical and functional properties, which are applicable in many branches of the construction industry. The most common and used phase of this system is MOC phase 5 ( known as MOC 5-1-8), whose formula is 5Mg(OH)2·MgCl2·H2O This phase crystallizes in the form of needle-shaped whiskers [18]. The interlocking of these crystals is one of the possible causes of the high strength of the binder [19]. The properties of MOC are influenced by its ability to absorb CO2 from the atmosphere [20,21] which results in the formation of magnesium carbonate phases on the surface of MOC

Methods

Results

Conclusion