Cementitious Product Curing with Dry Steam and CO2 Mixture
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Solution Overview
Problem
Existing methods for curing cementitious articles, such as concrete, are energy-intensive and costly, necessitating the development of alternative accelerated curing techniques that reduce production time and energy consumption while maintaining product quality.
Innovation Solution
A method involving the use of a curing chamber with controlled humidity and temperature, where a mixture of dry steam and CO2 is introduced to react with cementitious articles containing tricalcium silicate, forming calcium hydroxide and calcium carbonate, thereby enhancing strength and achieving significant CO2 uptake, potentially exceeding 15% by weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If accelerated curing is used to increase productivity and reduce curing time, then the curing duration is reduced from 7-30 days to 8-48 hours, but energy requirements become cost prohibitive
Solution Approach 1:
The invention changes the chemical composition parameters of the curing atmosphere by introducing CO2 (2-20% by volume) in addition to steam, creating a new curing environment that achieves accelerated curing with reduced energy consumption compared to traditional steam curing alone
Solution Approach 2:
The invention converts CO2, typically considered a harmful greenhouse gas, into a beneficial curing agent that accelerates cement hydration and strength development while simultaneously sequestering the CO2 in the cement matrix, thus transforming an environmental problem into a technical solution
2Use of energy by moving object
If traditional slow air curing is used to maintain low energy consumption, then energy costs are reduced, but productivity decreases due to extended curing time of 7-30 days
Solution Approach 1:
The invention applies preliminary chemical action by introducing CO2 that reacts with calcium hydroxide to form calcium carbonate, pre-enhancing the cement structure before final strength development, thereby enabling faster subsequent strength gain without excessive energy input
3Quantity of substance
If high concentration of CO2 is used to maximize CO2 uptake and strength enhancement, then CO2 sequestration increases to at least 15% by weight, but the complexity of controlling the curing atmosphere increases
Solution Approach 1:
The invention uses partial action by applying CO2 at moderate concentrations (2-20% by volume) rather than extreme concentrations, achieving sufficient CO2 uptake (at least 15% by weight) and strength enhancement while avoiding the need for complex high-pressure or high-purity CO2 systems
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 accelerates the curing process, increases the compressive strength of cementitious products, and enhances CO2 sequestration, reducing thermal expansion and microcracks, leading to improved product quality and potentially lower manufacturing costs.
Implementation Method 1
Ca(OH)2 is formed in the cementitious article by at least one of the reactions 2Ca3SiO5(s) + 7H2O(l) → 3CaO·2SiO2·4H2O(s) + 3Ca(OH)2(s), and 2Ca3SiO5(s) + 7H2O(g) → 3CaO·2SiO2·4H2O(s) + 3Ca(OH)2(s). Also, CO2 from the mixture of dry steam and CO2 reacts with the cementitious article to form CaCO3 in the cementitious article by at least one of the reactions 2Ca3SiO5(s) + 3CO2(g) + 4H2O(l) → 3CaO·2SiO2·4H2O(s) + 3CaCO3(s), and Ca(OH)2(s) + CO2(g) → CaCO3(s) + H2O(l)
Implementation Method 2
The cured cementitious article has a CO2 uptake of at least 15%, by weight
Data Source
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AI summary
A method for curing cementitious articles includes flowing dry steam and carbon dioxide (CO2) simultaneously into a curing chamber containing a cementitious article. A relative humidity within the curing chamber may be between about 50% and about 70% and a temperature within the curing chamber may be between about 50°C and about 70°C. A dry steam and CO2 mixture with a CO2 concentration between 2.5 vol% and 40 vol% is provided in the curing chamber and the cementitious article is cured for a duration between about 4 hours and 16 hours. Cementitious products cured with the method may have a CO2 uptake of greater than 15 wt% and a mechanical strength at least 10% greater than a cementitious product cured only in dry steam or CO2.