Latent Aluminosilicate Binder for Corrosion Protection
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Solution Overview
Problem
Conventional hydraulic binders, such as Portland cement, suffer from brittleness and limited durability due to high calcium content, and sacrificial anodes like zinc passivate in contact with calcium ions, leading to ineffective corrosion protection in concrete structures, especially under dry-wet cycles.
Innovation Solution
A hydraulic binder comprising latently hydraulic aluminosilicate glass and an alkali activator with a specific molar ratio, along with additives like pozzolans and zinc salts, which forms a durable, elastic matrix that maintains anode activity even in low humidity and reduces calcium hydroxide content, preventing passivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional hydraulic binders with high calcium content are used, then high strength is achieved, but brittleness increases and durability decreases
Solution Approach 1:
The patent fundamentally changes the chemical composition parameters of the binder by using latently hydraulic aluminosilicate glass with a specific (CaO+MgO+Al2O3)/SiO2 ratio greater than 1, replacing conventional high-calcium Portland cement. This parameter change achieves both high strength and improved durability by eliminating the brittleness associated with high calcium content while maintaining the strength-forming capability through the specific aluminosilicate glass composition and controlled hydration products.
Solution Approach 2:
The invention creates a composite binder system combining latently hydraulic aluminosilicate glass with alkali activators (such as calcium hydroxide, sodium hydroxide, or potassium hydroxide) and supplementary cementitious materials like pozzolans. This composite approach allows the system to achieve high strength through the glass matrix while the alkali activators and pozzolans contribute to durability by controlling pore solution chemistry and reducing calcium hydroxide content, thereby preventing degradation over time.
2Reliability
If zinc anodes are applied to protect steel in concrete, then galvanic corrosion protection is achieved, but zinc passivates in contact with calcium ions and becomes inactive
Solution Approach 1:
The patent converts the harmful effect of calcium ions (which cause zinc passivation) into a beneficial component by using calcium hydroxide as an alkali activator in the binder system. The calcium hydroxide provides the necessary alkaline environment to activate the latently hydraulic glass while simultaneously preventing zinc passivation by maintaining a controlled pH environment that keeps zinc anodes active. This transforms the previously harmful calcium presence into a protective mechanism for the galvanic anode.
Solution Approach 2:
The invention changes the chemical environment parameters around the zinc anode by controlling the binder composition to maintain optimal pH levels and calcium ion concentration. By using latently hydraulic aluminosilicate glass with specific composition ratios and activating it with controlled amounts of alkali, the system creates a pore solution environment that prevents zinc passivation while still providing effective galvanic protection, thereby extending the operational duration of the anode.
3Reliability
If alkalis are added to activate zinc anodes, then anode activity is improved, but alkali-silica reaction negatively affects concrete strength
Solution Approach 1:
The patent precisely controls the parameters of alkali addition by using alkali activators with specific concentrations and compositions (such as calcium hydroxide, sodium hydroxide, or potassium hydroxide at controlled dosages). The latently hydraulic aluminosilicate glass composition is specifically designed with (CaO+MgO+Al2O3)/SiO2 ratio greater than 1 to react with the alkalis in a controlled manner, producing hydration products that activate the zinc anode without excessive free alkalis that would cause harmful alkali-silica reactions, thus maintaining concrete strength while achieving anode activation.
Solution Approach 2:
The invention creates local quality differences in the binder system by concentrating alkali activators in specific regions where they are needed for zinc anode activation, while the overall binder matrix maintains a composition that prevents widespread alkali-silica reactions. The latently hydraulic glass provides localized reaction zones that consume alkalis productively, creating a gradient of alkalinity that activates anodes locally without compromising the overall structural strength of the concrete.
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
The binder provides high strength, elasticity, and long-term durability for concrete and metal coatings, while maintaining anode activity and preventing corrosion, even under dry-wet cycles, with enhanced resistance to alkali-silica reactions and improved workability.
Implementation Method 1
a latently hydraulic aluminosilicate glass having a ratio of (CaO+MgO+Al2O3)/SiO2 > 1
Implementation Method 2
an alkali activator of the empirical formula (I) a(M2O)*x(SiO2)*y(H2O) wherein M=Li, Na, K, a=0-4, and x=0-5 and y=3-20
Implementation Method 3
The effect of GCP is based on the formation of a galvanic element between a sacrificial anode and the steel
Implementation Method 4
zinc passivates in contact with calcium ions, especially calcium hydroxide, and is inactivated after a short period
Data Source
AI summary
The invention relates to a hydraulic binder, comprising K, Ca, aluminosilicates, as well as optionally Li, Na, and Mg, wherein the binder comprises the following components: a) a latently hydraulic aluminosilicate glass with a ratio of (CaO+MgO+Al2O3)/SiO2>1 and b) an alkali activator of the empirical formula (I) a(M2O)*x(SiO2)*y(H2O) (I) wherein M=Li, Na, K, a=0-4, and x=0-5 and y=3-20, wherein the molar ratio of Ca/Si is <1, the molar ratio of Al/Si is <1, and the molar ratio of M/Si is >0.1. Furthermore, it relates to binder matrices, mortars, concrete adhesives, and metal anodes made of such binder.