Silane-Modified Magnesium Oxychloride Cement Water Resistance
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Solution Overview
Problem
Magnesium oxychloride cement (MOC) exhibits poor water resistance, carbon sequestration, and corrosion issues due to its hydrophilic nature and porous structure, leading to degradation and steel corrosion in moisture-rich environments, with existing modifications only providing limited improvements.
Innovation Solution
The development of Silane Modified Magnesium Oxychloride Cement (SMMOC) with a stoichiometrically accurate ratio of MgO to MgCl2, combined with additional cementitious materials and organic fibers, and the use of active cationic organo-silane to enhance water resistance and corrosion resistance, while minimizing carbon sequestration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional MOC is used, then high strength and fire resistance are achieved, but water resistance is poor due to hydrophilic behavior and porous structure
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating silane-modified magnesium oxychloride cement with specific ratios of MgO to MgCl2 (2.5:1 to 3.5:1), adding silane compounds (0.1-5% by weight), phosphates (0.05-5% by weight), and other modifiers to transform the hydrophilic MOC into a water-resistant material while preserving its high strength and fire resistance properties
Solution Approach 2:
The patent creates a composite material system by combining silane-modified MOC with phosphates, silane compounds, and other additives to form a multi-component composition that simultaneously achieves water resistance, high strength, and fire resistance, overcoming the limitations of conventional single-component MOC
2Productivity
If conventional MOC is used, then initial setting and early strength are achieved, but long-term durability deteriorates due to carbon sequestration and degradation
Solution Approach 1:
The patent applies silane modification and phosphate addition during the manufacturing process to pre-establish a protective chemical structure that prevents carbon sequestration and degradation before the MOC is exposed to environmental conditions, ensuring both early strength and long-term durability from the outset
Solution Approach 2:
The patent converts the naturally hydrophilic and porous structure of MOC, which normally leads to carbon sequestration and degradation, into a beneficial feature by using silane compounds and phosphates to create a controlled porous structure that allows early carbonation for strength while preventing long-term carbon sequestration and degradation through hydrophobic modification
3Adaptability or versatility
If MOC absorbs moisture through pore structure, then breathability is achieved, but corrosion of steel occurs due to electrolyte formation
Solution Approach 1:
The patent changes the surface energy parameters of the MOC pore structure by incorporating silane compounds (0.1-5% by weight) and phosphates (0.05-5% by weight), transforming the hydrophilic pore structure into a hydrophobic one that maintains breathability while preventing moisture absorption and electrolyte formation that causes steel corrosion
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
SMMOC demonstrates improved durability, water resistance, corrosion resistance, and reduced carbon sequestration, maintaining structural integrity and fire resistance in high moisture environments, with enhanced bonding and reduced degradation over the long-term.
Implementation Method 1
addition of a hydrophobic agent, preferably active cationic organo-silane
Implementation Method 2
phosphoric acid in the composition, or applying water repellent agents on the finished product. Until now the most effective modifier for water resistance for MOC are phosphates
Implementation Method 3
During the hydration process of MOC, different phases of needle like crystal structures are formed
Implementation Method 4
Brucite reacts with CO2 from the air and a surface layer of magnesium chlorocarbonate (Magnesite)—(Mg(OH)2.2MgCO3.MgCl2.6H2O)—also known as efflorescence—is formed. This is called carbon sequestration of MOC
Implementation Method 5
chloride ions favour the diffusion to the metal and destroy the passive oxide layer, thereby leading to corrosion of the metal
Implementation Method 6
the moisture ingress into the MOC matrix causes chloride ions to adsorb on the absorbent surface by forming an electrolyte film layer
Data Source
AI summary
A magnesium oxychloride cement (MOC) incorporating an emulsion of active cationic organo-silane and method of making same.