Ultra-fine Fly Ash Cementitious Material for Room Temperature Curing
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Solution Overview
Problem
The existing alkali-activated fly ash (AAFA) cementitious materials face challenges in achieving rapid setting and high early strength at room temperature due to high activation energy and polymerization degree, leading to energy-intensive high-temperature curing and limited scalability in on-site construction.
Innovation Solution
A room temperature curable quick-setting high-strength AAFA cementitious material is prepared by mixing a pre-activated solution of sodium hydroxide and highly reactive ultra-fine fly ash with undisturbed fly ash, accelerating the polymerization reaction through increased surface defects and specific surface area, allowing for rapid setting and high strength development without high-temperature curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-temperature curing is adopted to achieve early strength, then strength is improved, but energy consumption increases
Solution Approach 1:
The patent changes the particle size parameter of fly ash from conventional sizes to ultra-fine size (d50 < 3 μm), which fundamentally alters the reaction kinetics and enables rapid strength development at room temperature, eliminating the need for high-temperature curing and associated energy consumption
Solution Approach 2:
The patent creates a composite system combining ultra-fine fly ash with specific alkaline activators (sodium hydroxide and/or sodium silicate) to achieve synergistic effects that accelerate polymerization at room temperature, resolving the contradiction between early strength and energy consumption
2Use of energy by moving object
If room temperature curing is used to reduce energy consumption, then energy consumption is reduced, but setting time increases and strength development is slow
Solution Approach 1:
The patent dramatically reduces the particle size of fly ash to ultra-fine dimensions (d50 < 3 μm) with specific surface area > 600 m²/kg, which increases the reactive surface area and enables rapid setting and strength development at room temperature without compromising productivity
Solution Approach 2:
The patent performs preliminary activation of ultra-fine fly ash with alkaline solutions before final mixing and casting, pre-initiating the polymerization process to accelerate subsequent setting and strength development at room temperature
3Device complexity
If conventional fly ash is used to simplify raw materials, then material complexity is reduced, but activation energy is too high for room temperature reaction
Solution Approach 1:
The patent changes the particle size parameter of fly ash to ultra-fine scale, which fundamentally alters the activation energy requirements by increasing surface area and creating more reactive sites, enabling room temperature activation without complicating the raw material system
4Productivity
If ultra-fine fly ash is used to increase specific surface area, then reaction activity is improved, but shrinkage increases due to C-A-S-H gel structure
Solution Approach 1:
The patent optimizes the alkaline activator composition parameters (modulus, concentration, ratio of sodium hydroxide to sodium silicate) to control the C-A-S-H gel structure formation, reducing shrinkage while maintaining high reaction activity of ultra-fine fly ash
Solution Approach 2:
The patent creates a composite gel structure through controlled polymerization of ultra-fine fly ash with alkaline activators, forming a more orderly N-A-S-H gel that compensates for shrinkage while maintaining high reactivity
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 enables rapid polymerization and early strength development at room temperature, broadening the material's application in on-site construction while reducing energy consumption and carbon footprint.
Implementation Method 1
a certain degree of depolymerization and amorphization caused by distortions and defects in the internal primary lattice
Implementation Method 2
a certain degree of depolymerization and amorphization caused by distortions and defects in the internal primary lattice
Implementation Method 3
significantly increased specific surface area and surface free energy, which in turn increases its chemical instability and its solid-liquid reaction interface with alkali-excited solutions
Implementation Method 4
The silicate-aluminate glass body in fly ash forms an amorphous three-dimensional network structure under the action of an alkaline activator
Implementation Method 5
the silicate-aluminate glass body in fly ash forms an amorphous three-dimensional network structure under the action of an alkaline activator
Implementation Method 6
the ability of silicate to accelerate the formation of silica-aluminous (N-A-S-H) gels of the AAFA polymerization product phase
Implementation Method 7
accelerate the formation of silica-aluminous (N-A-S-H) gels of the AAFA polymerization product phase
Data Source
AI summary
Disclosed are a room temperature curable quick-setting high-strength alkali-activated fly ash (AAFA) cementitious material and a preparation method thereof, belonging to the technical field of building materials. The raw materials include: in parts by mass, 30-50 parts of undisturbed fly ash, 50-70 parts of highly reactive ultra-fine fly ash, and 12-18 parts of sodium hydroxide. Specifically, the AAFA with fast setting and high strength for room temperature curing is prepared by pretreatment of fly ash with sodium hydroxide exciter, based on a premise that the raw material system and preparation process are simplified and feasible.