LC3 Cement Composition for Low Carbon Footprint and High Strength
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Solution Overview
Problem
The cement production industry faces challenges in reducing carbon footprint while maintaining high early strength, durability, and workability in concrete mixes, as traditional Portland cement-based mixes contribute significantly to carbon dioxide emissions and produce pollutants.
Innovation Solution
A limestone calcined clay cement (LC3) composition is developed, comprising a cementitious binder with calcium silicate and aluminate mineral phases, a supplementary cementitious material with calcined clay and carbonate rock powder, and additives like glyoxylic acid and borate sources to control ettringite formation, reducing the amount of cementitious binder and water-to-cement ratio, thereby enhancing early strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional Portland cement is used to ensure high early strength and durability, then the concrete achieves required mechanical properties, but carbon dioxide emissions and environmental pollution increase significantly
Solution Approach 1:
The invention changes the chemical composition parameters of the cementitious binder by incorporating limestone (calcium carbonate) and calcined clay materials alongside Portland cement clinker. This creates a multi-component system (LC3 cement) with optimized ratios of calcium silicate phases, aluminate phases, and carbonate materials that maintains hydraulic reactivity and early strength development while reducing the proportion of high-carbon Portland cement clinker
Solution Approach 2:
The invention uses a composite cementitious binder system combining multiple materials: Portland cement clinker (40-70 wt%), limestone (10-30 wt%), and calcined clay material (10-30 wt%). This composite approach leverages the complementary properties of each component - the hydraulic activity of clinker, the filler and pozzolanic effects of limestone, and the reactivity of calcined clay - to achieve durable concrete with reduced carbon footprint
2Object-generated harmful factors
If the amount of cementitious binder is reduced to lower carbon footprint, then environmental impact decreases, but early strength and durability may be compromised
Solution Approach 1:
The invention optimizes the mineralogical composition parameters of the cementitious binder, specifically ensuring adequate content of calcium silicate phases (C3S, C2S) for strength development and calcium aluminate phases for early reactivity. The Blaine surface area is controlled at 3800-5500 cm²/g to enhance hydration kinetics, enabling reduced cement content while maintaining early strength
Solution Approach 2:
The invention introduces calcined clay material as an intermediary component that provides pozzolanic reactivity and fills microvoids in the cement matrix. This material acts as a mediator that enhances the overall performance of the reduced-cement system by improving densification and secondary hydration, thereby maintaining strength and durability with lower cementitious binder content
3Strength
If water-to-cement ratio is reduced to improve strength and durability, then mechanical properties and durability enhance, but workability and flowability deteriorate
Solution Approach 1:
The invention changes the surface area parameter of the cementitious binder by controlling the Blaine surface area to be at least 3800 cm²/g. Higher surface area increases the reactive surface available for hydration, improving early strength development and allowing lower water-to-cement ratios while maintaining workability through enhanced particle packing and reduced capillary porosity
4Ease of operation
If dispersants and water-reducing agents are added to improve workability at low water-to-cement ratio, then flowability improves, but the complexity of the mixture increases
Solution Approach 1:
The invention uses limestone particles as an intermediary filler material that improves particle packing density and lubricates the mixture, enhancing flowability without requiring excessive chemical admixtures. The calcined clay material also acts as a mediator by providing surface area for adsorption and improving the rheological properties of the paste, reducing dependence on complex dispersant 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
The LC3 composition achieves high early strength and durability with a reduced carbon footprint by optimizing the mineral phases and additives, allowing for a lower cement content and improved workability, while minimizing environmental impact.
Implementation Method 1
Upon hydration of a cementitious system, ettringite is generated in a rapid reaction
Implementation Method 2
Ettringite is a calcium aluminum sulfate compound having the formula Ca6Al2(SO4)3·32H2O
Implementation Method 3
A further quantity of water is adsorbed at the newly developing ettringite surfaces
Implementation Method 4
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
Data Source
Figure 1
AI summary
A limestone calcined clay cement 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, in an amount of 180 to 400 kg per m³ of the freshly mixed construction composition; b) a supplementary cementitious material having a Dv90 of less than 200 µm, in a total amount of 50 to 100 parts by weight, relative to 100 parts by weight of cementitious binder a), the supplementary cementitious material comprising (b-1) a calcined clay material and (b-2) a carbonate rock powder in a weight ratio of (b-1) to (b-2) in the range of 0.5 to 2; c) optionally, an extraneous aluminate source; d) a sulfate source; and e) a polyol in an amount of 0.3 to 2.5 wt.-%, relative to the amount of cementitious binder a). The composition contains available aluminate, calculated as Al(OH)4–, from the calcium aluminate mineral phases plus the optional extraneous aluminate source, per 100 g of cementitious binder a), in a total amount of at least 0.08 mol, if the amount of cementitious binder a) is in the range of 180 to less than 220 kg per m³ of the freshly mixed composition, at least 0.06 mol, if the amount of cementitious binder a) is in the range of 220 to less than 280 kg per m³ of the freshly mixed composition, and at least 0.05 mol, if the amount of cementitious binder a) is 280 kg or more per m³ of the freshly mixed composition; 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 comprising (i) glyoxylic acid, a glyoxylic acid salt and/or a glyoxylic acid derivative; and (ii) at least one of (ii-a) a borate source and (ii-b) a carbonate source, wherein the carbonate source is selected from inorganic carbonates having an aqueous solubility of 0.1 g·L-1 or more, organic carbonates, and mixtures thereof; and g) a co-retarder selected from (g-1) α-hydroxy monocarboxylic acids and salts thereof, (g-2) phosphonic acids and salts thereof, (g-3) polycarboxylic acids and salts thereof, and mixtures thereof. The limestone calcined clay cement construction composition is a reduced carbon footprint composition and exhibits high early strength, high final strength, sufficient open time and high durability. Ingredients of the construction composition are abundantly available.