Hydraulic Binder with Phosphate Activators for Low pH Slag Activation
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Solution Overview
Problem
Existing hydraulic binders, such as those using blast furnace slag or fly ash, require high alkalinity activators that increase pH, making handling difficult and pose health risks, and are not effective for partially crystallized or coarse slag particles.
Innovation Solution
A hydraulic binder system comprising at least 70% solid mineral compounds with a calcium oxide and magnesium oxide mixture, activated by a system containing at least 30% of a salt derived from phosphoric acid, an alkali metal silicate, and an alkaline earth metal source, which improves mechanical resistance and allows activation of amorphous and partially crystallized slags up to 5 mm in size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high alkalinity activators are used to activate slag or fly ash, then the hydraulic reactivity is improved, but the pH increases making handling difficult and posing health risks
Solution Approach 1:
The patent changes the chemical composition parameters of the activation system by using salts derived from phosphoric acid (such as sodium triphosphate) combined with alkali metal silicates and alkaline earth metal sources, replacing traditional high-alkalinity activators. This parameter change achieves effective activation while maintaining lower and safer pH levels
Solution Approach 2:
The invention uses a composite activation system combining three types of compounds: salts from phosphoric acid, alkali metal silicates, and alkaline earth metal sources. This composite approach provides synergistic effects that enable effective activation of slag and fly ash without requiring high alkalinity from any single component
2Reliability
If conventional activation systems are used, then amorphous slag can be activated, but partially crystallized or coarse slag particles cannot be effectively activated
Solution Approach 1:
The activation system is designed with multi-functionality to effectively activate various types of slag including amorphous slag, partially crystallized slag, and coarse slag particles up to 5 mm in size. The combination of phosphoric acid salts, alkali metal silicates, and alkaline earth metal sources provides universal activation capability across different slag compositions and morphologies
Solution Approach 2:
The patent modifies the chemical parameters of the activation system by incorporating specific ratios of phosphoric acid salts (at least 30% by weight), alkali metal silicates, and alkaline earth metal sources, which enables the system to adapt to and activate diverse slag types with varying degrees of crystallinity and particle sizes
3Strength
If Portland cement is used to achieve desired compressive strength, then mechanical performance is met, but CO2 emissions increase
Solution Approach 1:
The patent utilizes industrial waste materials such as slag and fly ash as the primary binding components (at least 70% by weight of the binder), which would otherwise be discarded. These materials self-activate through the proposed activation system, converting waste into valuable construction materials with adequate mechanical strength while avoiding CO2 emissions associated with Portland cement production
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 achieves compressive strength comparable to Portland cement while being environmentally and health-safe, with improved mechanical resistance and compatibility with various applications, including quick resistance at young ages and controlled reactivity.
Implementation Method 1
intended to improve and/or accelerate the setting and/or hardening of the binder, in particular by facilitating the dissolution of its components
Data Source
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AI summary
The invention relates to a hydraulic binder comprising at least 70 wt. % of a solid mineral compound consisting of at least a mixture of silica, alumina and alkaline-earth oxides, the total amount of CaO and MgO representing at least 10 wt. % of the solid mineral compound, and an activation system of which at least 30 wt. % is a salt derived from phosphoric acid. The invention also relates to building products produced from a mortar composition comprising such a binder.