Set-Delayed Cement with Pumice for Low-Temperature Strength
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Solution Overview
Problem
Set-delayed cement compositions, particularly those with Portland cement, face gelation issues and limited effectiveness at lower temperatures, restricting their use in surface cementing operations, while compositions with hydrated lime and quartz may not develop sufficient compressive strength in low-temperature applications.
Innovation Solution
A set-delayed cement composition comprising water, pumice, hydrated lime, and a set retarder, optionally with a dispersant and cement set activator, which remains in a pumpable fluid state for extended periods and develops reasonable compressive strengths at low temperatures, preventing alkali silicate reactions that cause cracks and deformations in concrete.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If set-delayed cement compositions are prepared with Portland cement, then they can remain in a pumpable fluid state for extended periods, but they experience undesired gelation issues which limit their use and effectiveness
Solution Approach 1:
The patent changes the chemical composition parameters by replacing Portland cement with a blend of hydraulic cement and non-hydraulic cement (such as lime-stabilized soil or fly ash). This parameter change modifies the setting characteristics to prevent gelation while maintaining extended pumpable fluid state, resolving the contradiction between duration and reliability
Solution Approach 2:
The patent uses composite cementitious materials combining hydraulic cement (for setting capability) with non-hydraulic cement components (for gelation prevention). This composite approach allows the composition to remain pumpable for extended periods without experiencing gelation issues, simultaneously achieving both improved duration and reliability
2Ease of manufacture
If set-delayed compositions comprise hydrated lime and quartz, then they may be effective in some operations, but they do not develop sufficient compressive strength when used in applications where low temperature may be an issue
Solution Approach 1:
The patent modifies the compositional parameters by incorporating supplementary cementitious materials such as class F fly ash or slag cement in specific proportions. These parameter changes enable the composition to develop adequate compressive strength at low temperatures while maintaining ease of manufacture and application effectiveness
Solution Approach 2:
The patent utilizes the porous structure of certain cementitious materials like fly ash to improve low-temperature strength development. The porous structure provides additional surface area for hydration reactions that can proceed at lower temperatures, thereby improving compressive strength without compromising manufacturability
3Device complexity
If cement composition is prepared in advance for surface applications, then capital expenditures are reduced due to reduction in need for on-site bulk storage and mixing equipment, but the composition must maintain stability during storage and transport
Solution Approach 1:
The patent applies preliminary action by pre-mixing the cement composition with all necessary components including water, admixtures, and aggregates at an off-site location. The composition is formulated to remain stable during storage and transport, eliminating the need for on-site mixing equipment while ensuring composition stability is maintained throughout the storage period
Solution Approach 2:
The patent uses chemical intermediaries such as set-retarding admixtures and dispersants to maintain composition stability during storage and transport. These intermediary substances prevent premature setting and aggregation, allowing the pre-mixed composition to remain stable without requiring complex on-site equipment while preserving compositional integrity
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 composition effectively remains fluid for extended periods, develops suitable compressive strength at low temperatures, and prevents alkali silicate reactions, enhancing the durability and integrity of concrete in various applications.
Implementation Method 1
A set-delayed cement composition comprising water, pumice, hydrated lime, and a set retarder
Implementation Method 2
preventing alkali silicate reactions that cause cracks and deformations in concrete
Implementation Method 3
develops reasonable compressive strengths at low temperatures
Data Source
AI summary
Disclosed is a method of spraying a surface with a set-delayed cement. The method comprises providing a set-delayed cement composition comprising water, pumice, hydrated lime, and a set retarder; spraying a surface with the set-delayed cement composition; and allowing the set-delayed cement composition to set on the surface.