Class C Fly Ash Cementitious Mixture with Boron Set Control
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Solution Overview
Problem
Current manufacturing of building products relies heavily on energy-intensive and carbon-intensive materials, limiting the use of Class C fly ash as a sole binder due to its variable chemical composition and reactivity, which complicates high-volume industrial processes and product performance.
Innovation Solution
A cementitious composition using Class C fly ash as the primary binder, combined with a set control system comprising boron and tartaric acid, allows for controlled reaction with water, enabling high-volume manufacturing and achieving desired performance standards such as compressive strength and freeze-thaw durability without additional air-entraining agents, while accommodating variability in fly ash reactivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If Class C fly ash is used as a sole binder in cementitious products, then the greenhouse gas footprint and energy consumption are reduced, but the variable chemical composition and reactivity of the fly ash compromise product performance and manufacturing consistency
Solution Approach 1:
A set control system comprising boron and tartaric acid is introduced as an intermediary to mediate between the variable fly ash and the desired consistent product performance. The boron component reacts with calcium compounds in the fly ash to form calcium borate, which controls the setting reaction. The tartaric acid provides a buffering effect that stabilizes pH and ensures consistent set times despite variations in fly ash composition.
Solution Approach 2:
The invention changes key chemical parameters by adding boron (0.01-5% by weight) and tartaric acid (0.1-10% by weight) to the fly ash mixture. These parameter changes transform the unpredictable reactivity of Class C fly ash into a controlled setting process, enabling consistent manufacturing while maintaining the environmental benefits of using fly ash as a sole binder.
2Ease of manufacture
If Class C fly ash with variable composition is used as binder, then the cost and environmental impact are improved, but the reactivity control and manufacturing precision deteriorate
Solution Approach 1:
The set control system acts as an intermediary that standardizes the setting process. The boron-tartaric acid combination creates a predictable chemical reaction pathway that overrides the variability in fly ash composition, enabling precise control over set times and ensuring consistent manufacturing quality at scale.
Solution Approach 2:
The buffering action of tartaric acid provides a form of chemical feedback that self-regulates the setting process. As the reaction progresses and pH changes occur, the tartaric acid resists drastic pH shifts, maintaining optimal conditions for continued reaction and ensuring consistent set times regardless of initial fly ash composition variations.
3Productivity
If high-volume manufacturing is implemented with Class C fly ash, then productivity increases, but the variability in fly ash reactivity complicates process control
Solution Approach 1:
By introducing fixed parameter additions of boron and tartaric acid to variable fly ash, the invention creates a standardized process that can be scaled. The chemical parameters of the set control system remain constant while the fly ash varies, allowing high-volume manufacturing with simplified process control despite input material variability.
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 solution enables the production of building products with enhanced structural integrity, reduced greenhouse gas emissions, and lower energy consumption, allowing for high-volume manufacturing with consistent product quality and performance.
Implementation Method 1
Class C fly ash, normally produced from the burning of sub-bituminous or lignite coal, usually demonstrates cementitious properties in addition to pozzolanic properties generally attributed to its higher free lime and calcium compound content. This calcium content may permit Class C fly ash to react with water without need for the presence of additional chemicals, and to generate reaction products capable with cementing properties.
Implementation Method 2
A cementitious composition using Class C fly ash as the primary binder, combined with a set control system comprising boron and tartaric acid, allows for controlled reaction with water
Data Source
AI summary
A cementitious mixture for high-volume production of masonry products comprises a hydraulic binder accounting for 20 wt % or more of the cementitious mixture, the hydraulic binder comprising 75 to 100 wt % Class C fly ash with a CaO equivalent content of at least 15% by weight. The cementitious mixture also comprises one or more aggregates, and a set control system.