Cement-Reduced Composition with Calcium Aluminate
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Solution Overview
Problem
The cement production industry contributes significantly to carbon dioxide emissions and pollution, and existing concrete mixes face challenges in achieving high early strength, durability, and reduced shrinkage while minimizing cement usage.
Innovation Solution
A cement-reduced construction composition is developed, comprising calcium silicate and calcium aluminate mineral phases, fine materials, a sulfate source, polyol, ettringite formation controllers, and co-retarders, which allows for a lower cement content while maintaining or improving workability and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If cement content is reduced to lower carbon footprint, then environmental impact is reduced, but achieving high early strength and durability becomes more difficult
Solution Approach 1:
The patent changes the chemical parameters of the binder system by incorporating calcium aluminate cement (CAC) alongside Portland cement, and by carefully controlling the molar ratios of aluminate to sulfate (0.4-2.0). This parameter change enables the formation of ettringite crystals that provide early strength while allowing reduced cement content. The specific Blaine surface area requirement (≥3800 cm²/g) also represents a parameter change to optimize reactivity.
Solution Approach 2:
The patent creates a composite binder system combining Portland cement, calcium aluminate cement, and fine materials (fly ash, slag, silica fume). This composite approach allows the different materials to contribute complementary properties: CAC provides rapid early strength through ettringite formation, while Portland cement provides long-term strength, and fine materials provide durability and workability enhancement.
2Object-generated harmful factors
If cement content is reduced to lower carbon footprint, then environmental impact is reduced, but durability and resistance to attacks becomes compromised
Solution Approach 1:
The composite binder system including Portland cement, calcium aluminate cement, and supplementary fine materials (fly ash, slag, silica fume) works synergistically to provide durability. The fine materials fill pores and refine the microstructure, while the controlled ettringite formation from CAC provides a dense, stable structure resistant to sulfate, carbonation, and freeze-thaw attacks.
Solution Approach 2:
The patent specifies critical parameter ranges: aluminate to sulfate molar ratio (0.4-2.0), available aluminate content (0.05-0.10 mol per 100g binder), and Blaine surface area (≥3800 cm²/g). These parameter controls ensure optimal ettringite formation that enhances durability by creating a dense microstructure that resists harmful penetrations while maintaining workability.
3Strength
If water/binder ratio is reduced to improve strength, then mechanical strength is improved, but workability and processing becomes difficult
Solution Approach 1:
The patent maintains a low water/binder ratio (0.25-0.35) to ensure high strength and durability, while compensating for workability through careful control of binder fineness (Blaine surface area ≥3800 cm²/g) and the inclusion of fine materials that improve flow characteristics. The high surface area ensures adequate surface coverage for bonding without requiring excess water.
4Productivity
If mold turnover rate is increased for productivity, then production efficiency is improved, but concrete must achieve high early strength quickly
Solution Approach 1:
The calcium aluminate cement is specifically selected to initiate rapid ettringite formation upon mixing, providing preliminary strength gain within the first few hours. This preliminary action enables early demolding and form reuse, directly supporting high productivity requirements. The available aluminate content (0.05-0.10 mol per 100g binder) is pre-calibrated to ensure optimal early-age strength development.
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 achieves high early strength, durability, and reduced shrinkage with a lower carbon footprint, enabling faster bridging of cementitious binder and fine material particles, and improved resistance to freeze-thaw, carbonation, and sulfate attacks.
Implementation Method 1
the molar ratio of total available aluminate to sulfate is 0.4 to 2.0
Implementation Method 2
suppress the formation of ettringite from the aluminate phases and to inhibit the crystallization of ettringite
Implementation Method 3
dispersants are added to aqueous slurries of hydraulic binders for improving their workability... capable of preventing the formation of solid agglomerates, and of dispersing the particles
Implementation Method 4
a polyol in an amount of 0.3 to 2.5 wt.-%... a co-retarder selected from (g-1) α-hydroxy monocarboxylic acids and salts thereof
Implementation Method 5
fastest bridging of cementitious binder and fine material particles
Implementation Method 6
composite material of a binding medium having particles or fragments of aggregate embedded therein
Implementation Method 7
improved resistance to freeze-thaw, carbonation, and sulfate attacks
Data Source
AI summary
A cement-reduced construction composition comprises a) a cementitious binder comprising one or more calcium silicate mineral phases and one or more calcium aluminate mineral phases, and having a Blaine surface area of at least 3800 cm2/g; b) a fine material having a Dv90 of less than 200 μm, selected from alkali-activatable binders, rock powders and inorganic pigments, or mixtures thereof; c) optionally, an extraneous aluminate source; d) a sulfate source; and e) a polyol. The composition contains a controlled amount of available aluminate, calculated as Al(OH)4−, from the calcium aluminate mineral phases plus the optional extraneous aluminate source; and the molar ratio of total available aluminate to sulfate is 0.4 to 2.0. The construction composition further comprises f) an ettringite formation controller and g) a co-retarder. The cement-reduced construction composition is a reduced carbon footprint construction composition and exhibits high early strength, high final strength, sufficient open time, high durability, and reduced shrinkage compared to ordinary Portland cement based mixes.