Calcium Oxide Particle Accelerator for Mineral Binders
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Solution Overview
Problem
Existing hardening accelerators for mineral binders, such as cement and concrete, often result in high early strength but compromise processing time and final strength, and are not effective under high pressure and temperature conditions, making them unsuitable for demanding applications like shotcrete and borehole cementing.
Innovation Solution
A composition comprising calcium oxide in particle form combined with a phosphoric acid ester of a polyhydric alcohol as an inhibitor, which stabilizes the calcium oxide in water, allowing for flexible use as a hardening accelerator that maintains effectiveness regardless of the time of addition and quality of binder components, while avoiding undesirable stiffening behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional hardening accelerators (amino alcohols, halides, nitrites, nitrates, aluminum salts, glycols, glycerin, or α-hydroxycarboxylic acids) are used to accelerate the setting and hardening of mineral binder compositions, then high early strength is achieved, but processing time is significantly reduced and final strength is compromised
Solution Approach 1:
The patent changes the chemical parameters of the accelerator system by using calcium oxide in particle form with specific surface area characteristics (5-50 m²/g) combined with phosphoric acid esters of polyhydric alcohols in specific amounts (0.01-5 wt% based on binder weight). This parameter optimization allows acceleration of early strength development while maintaining adequate processing time and final strength, resolving the contradiction between early strength and processing time.
Solution Approach 2:
The patent creates a composite accelerator system combining calcium oxide particles with phosphoric acid esters of polyhydric alcohols. This composite approach synergistically accelerates early strength development while the phosphoric acid ester component moderates the reaction rate, preserving processing time and final strength characteristics that would be compromised by conventional single-component accelerators.
2Speed
If well-known accelerator systems are used to cause very quick setting, then setting speed is improved, but the mineral binder compositions cannot undergo further processing after mixing
Solution Approach 1:
The patent creates a dynamic hardening profile where the calcium oxide-phosphoric acid ester system provides initial acceleration for quick setting, then the reaction rate naturally modulates to allow continued processing. The phosphoric acid ester acts as a rate-controlling agent that enables the system to transition from rapid initial setting to a more gradual hardening phase, providing processing flexibility.
3Strength
If conventional admixtures are used for borehole cementing, then some acceleration effect is achieved, but they are only partially effective under high temperature and pressure conditions
Solution Approach 1:
The patent optimizes the physical parameters of calcium oxide (particle size, specific surface area) and the chemical composition (phosphoric acid ester of polyhydric alcohol) to create a system that remains effective under high temperature and pressure conditions. The particle morphology and surface area characteristics ensure consistent reactivity across extreme conditions, providing reliable hardening acceleration for borehole cementing applications.
Data Source
AI summary
The present invention relates to compositions, in particular a setting accelerator for mineral binders, containing or consisting of: a) calcium oxide in the particle form; b) an inhibitor for the reaction of calcium oxide with water and c) optionally water.