Low-Temperature Cementitious Compositions with Accelerated Curing
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Solution Overview
Problem
Cementitious compositions that cure by hydraulic reaction with water are significantly retarded at low temperatures, leading to prolonged setting times and slow curing, especially at temperatures below 5° C., which can result in incomplete curing and increased waiting periods before further work can be done, posing challenges in climate zones with low temperatures.
Innovation Solution
A cementitious composition based on OPC-rich blends with CAC and/or CSA, incorporating a powder P of carbonates or hydrogen carbonates and an accelerator component with alkanolamines, halides, and anti-freeze agents, allowing accelerated curing at temperatures as low as −10° C. without the need for tempering of materials or heating, while maintaining good workability and low shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cementitious compositions are used at low temperatures, then the compositions can be applied in cold climate zones, but the curing is significantly retarded leading to prolonged setting time and slow strength development
Solution Approach 1:
The patent changes the chemical parameters of the cementitious composition by incorporating specific accelerators (alkali metal carbonates, alkaline earth metal carbonates, and their hydrogen carbonates) in controlled amounts (0.1-15 wt% based on total binder weight). These parameter changes enable the composition to cure properly at low temperatures (down to -10°C) without requiring external heating or material tempering, thus resolving the contradiction between cold climate applicability and excessive curing time
Solution Approach 2:
The patent creates a composite cementitious system combining ordinary Portland cement (15-69 wt%), calcium aluminate cement (1-25 wt%), calcium sulfoaluminate cement (1-25 wt%), and carbonate/hydrogen carbonate additives. This composite formulation synergistically accelerates early strength development at low temperatures while maintaining workability, allowing application in cold climates without the time loss associated with conventional single-cement systems
2Productivity
If specialized cements (CAC or CSA) are used to accelerate curing, then the curing speed increases, but the long-term ageing performance deteriorates and shrinkage increases
Solution Approach 1:
The patent optimizes the proportioning parameters of CAC and CSA relative to OPC, limiting CAC to 1-25 wt% and CSA to 1-25 wt% of the total composition. This parameter control ensures that the accelerators (carbonates and hydrogen carbonates) enhance early curing speed without allowing excessive CAC/CSA content that would cause long-term ageing problems and increased shrinkage, thus balancing productivity and reliability
Solution Approach 2:
The patent introduces carbonate and hydrogen carbonate compounds as intermediary substances that mediate between OPC and the small amounts of CAC/CSA. These intermediaries accelerate the hydraulic reaction at low temperatures through chemical mechanisms that do not trigger the harmful long-term effects associated with high CAC/CSA content, thereby enabling fast curing while preserving long-term performance
3Reliability
If measures such as tempering of raw materials or heating of job sites are taken to enable curing at low temperatures, then the curing proceeds normally, but the process becomes difficult, expensive or even impossible
Solution Approach 1:
The patent makes the cementitious composition self-sufficient for low-temperature curing by incorporating chemical accelerators (carbonates and hydrogen carbonates) that internally generate the necessary reaction acceleration. The composition does not require external services such as heated mixing equipment, warmed aggregates, or heated job sites, thereby eliminating the complexity and cost associated with these measures while ensuring reliable curing at temperatures down to -10°C
Data Source
AI summary
A cementitious composition with accelerated curing at low temperatures particularly at temperatures <5° C., especially at temperatures <0° C. The cementitious composition consists of 2 components with a first component A including at least one ordinary Portland cement, at least one cement selected from calcium aluminate cement and/or calcium sulfoaluminate cement, a powder P, selected from the group consisting of carbonates or hydrogen carbonates of alkali and/or alkaline earth metals, optionally aggregates, optionally other additives and a second component B comprising at least one accelerator, an anti-freeze agent, water, and optionally other additives. The composition shows increased development of compressive strength, maintain good workability, and have particularly low shrinkage, also when cured at temperatures <5° C., especially <0° C., and as low as −10° C.