Carbonation-Hardening Binder for Low-CO2 Building Elements
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Solution Overview
Problem
Cement-based construction materials face challenges in reducing energy consumption and CO2 emissions, as carbonation-hardening binders require high CO2 concentrations and elevated temperatures, making them expensive and impractical for widespread use.
Innovation Solution
A binder comprising at least 8% ternesite, 15% dicalcium silicate, and 5% ye'elimite, which reacts hydraulically to form hydrated phases and capillary pores, enabling carbonation hardening at ambient conditions without the need for high CO2 concentrations or temperatures, utilizing self-desiccation for enhanced carbonation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If carbonation-hardening binders are used to reduce CO2 emissions, then CO2 absorption during hardening increases, but high CO2 concentrations and elevated temperatures are required which increases cost and complexity
Solution Approach 1:
The binder composition performs self-desiccation during hydraulic setting, automatically creating the required porosity and conditions for rapid carbonation without external intervention. The system serves itself by generating the necessary microstructure through hydraulic reaction that subsequently enables fast CO2 uptake at ambient conditions
Solution Approach 2:
The invention changes the chemical composition parameters of the binder by incorporating specific phases (ternesite, dicalcium silicate, ye'elimite) that alter the hardening mechanism. This compositional change enables the material to achieve both hydraulic setting and subsequent rapid carbonation at ambient temperature and pressure, eliminating the need for elevated temperatures and high CO2 concentrations
2Productivity
If high CO2 concentration and elevated temperature are applied for carbonation hardening, then carbonation speed increases, but energy consumption and cost increase
Solution Approach 1:
The hydraulic reaction is performed first as a preliminary action that consumes water and creates capillary pores and carbonatable phases. This preliminary hydraulic setting prepares the microstructure in advance, enabling rapid carbonation to occur subsequently at ambient conditions without requiring energy-intensive elevated temperatures or pressures
3Ease of manufacture
If diffusion of CO2 from atmosphere is used for carbonation, then no additional CO2 supply is needed, but carbonation takes too long
Solution Approach 1:
The hydraulic reaction creates a porous microstructure with capillary pores that dramatically increases the surface area and accessibility for CO2 diffusion. This self-generated porosity accelerates the diffusion rate of atmospheric CO2 into the binder matrix, reducing curing time from days to hours while maintaining simplicity of CO2 supply
4Strength
If Portland cement is used for hydration hardening, then strength is achieved, but energy consumption and CO2 emission increase
Solution Approach 1:
The invention uses a composite binder system combining multiple phases (ternesite, dicalcium silicate, ye'elimite) that work together to provide both hydraulic strength development and subsequent carbonation hardening. This composite approach achieves comparable or superior strength to Portland cement while significantly reducing CO2 emissions through the carbonation mechanism
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
This approach reduces CO2 generation during hardening, allows for the use of low-grade raw materials, and achieves fast and efficient carbonation hardening, providing high strength and durability in building elements without the need for expensive curing methods.
Implementation Method 1
the binder paste is reacted hydraulically to form hydrated phases and capillary pores
Implementation Method 2
binders hardening through carbonation
Implementation Method 3
Supply from the surrounding atmosphere via diffusion takes too long
Implementation Method 4
by a self desiccating action, a porosity for fast and enhanced carbonation hardening
Data Source
AI summary
A method of manufacturing building elements has the steps: providing a binder comprising at least 8% by weight ternesite, at least 15% by weight dicalcium silicate and at least 5% by weight ye'elimite, each with respect to the total binder, as hydraulically reactive phases; mixing the binder with water to form a paste; casting the paste into a desired shape for the building element; reacting the paste hydraulically to form calcium-silicate-hydrates, calcium-aluminium-silicate-hydrates, portlandite, brucite, strätlingite, hydrotalcite-like phases and ettringite/AFm and capillary pores, and carbonation hardening to provide the building element and to building elements obtainable by the method.