Accelerator Powder for Rapid Cement Setting
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Solution Overview
Problem
Current methods for accelerating cement hydration do not effectively achieve rapid setting and strength development, particularly within 90 minutes and 3 hours, and often require expensive specialty cements or energy-intensive heating, while also leading to excessive shrinkage and potential cracking.
Innovation Solution
A nontoxic, inexpensive accelerator powder composed of a combination of water-insoluble mineral powders, such as calcium carbonate or dolomite, and compounds like alkali metal nitrates, thiocyanates, or hydroxyalkylamines, which significantly accelerates cement-based composition setting and reduces shrinkage, allowing for rapid strength development and improved processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If temperature is increased to accelerate cement hydration, then setting speed is improved, but energy consumption increases and severe drying occurs leading to insufficient hydration
Solution Approach 1:
The patent changes the chemical composition parameters of the binder system by introducing specialty cements (calcium aluminate cement, calcium sulfoaluminate cement) in combination with accelerators based on lithium salts, replacing the need for thermal acceleration while achieving rapid setting through chemical acceleration mechanisms
2Speed
If specialty cements and lithium salt accelerators are used to achieve rapid setting, then setting speed is improved, but cost increases and availability is limited
Solution Approach 1:
The patent replaces expensive specialty cements and lithium salt accelerators with a combination of conventional Portland cement and accelerators based on calcium nitrite, which are inexpensive, widely available, and achieve comparable rapid setting performance
Solution Approach 2:
The patent replicates the rapid setting effect achieved by specialty cements and lithium salts by using a different chemical system (calcium nitrite accelerators with conventional cement) that produces similar kinetic outcomes without the cost and availability constraints
3Speed
If conventional accelerators are used to accelerate cement hydration, then setting speed is improved, but shrinkage increases leading to crack formation
Solution Approach 1:
The patent uses a composite binder system combining conventional Portland cement with calcium nitrite accelerator and calcium aluminate cement or calcium sulfoaluminate cement, creating a multi-component system that achieves rapid setting while the aluminate phases help control shrinkage and reduce crack formation
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 accelerator powder enables rapid setting and strength development in cement-based compositions, reducing shrinkage and crack formation, making it suitable for applications like 3D printing, while being cost-effective and widely available, with the ability to control setting times and enhance early strength development.
Implementation Method 1
If cement is mixed with water, it cures in a chemical process, namely cement hydration. In cement hydration, also referred to as setting of the cement, cement hydrates are formed.
Implementation Method 2
The accelerator powder and the mixture of the accelerator powder with cement can be mixed simply and homogeneously with the further constituents of a mortar or concrete and be used very well in finished dry mortar or dry concrete mixtures
Data Source
AI summary
An accelerator powder for cement and also rapid-setting binder compositions which contain the accelerator powder and the use in mortar or concrete. The accelerator powder includes from 10 to 99.7% by weight of a water-insoluble mineral powder P and from 0.3 to 90% by weight of at least one compound V selected from the group consisting of alkali metal halides and alkaline earth metal halides, alkali metal nitrates and alkaline earth metal nitrates, alkali metal nitrites and alkaline earth metal nitrites, alkali metal thiocyanates and alkaline earth metal thiocyanates and hydroxyalkylamines or salts thereof, and mixtures thereof.