Bio-Sourced Binder Composition for Faster Setting Hemp Concrete
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Solution Overview
Problem
Hemp and wood-based construction materials face issues due to their high hydrophilicity, leading to excessive water absorption, inconsistent drying, and delayed or inhibited setting of mineral binders, resulting in poor mechanical properties and performance instability.
Innovation Solution
A binder composition with a specific surface area greater than 10 m²/g, comprising powdered hydrated lime and colloidal clays, is used to enhance interaction with organic additives, reducing the adverse effects of plant-based aggregate decomposition products, thereby promoting faster setting and improving mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plant-based aggregates (hemp, wood) are used in mortars and concretes, then thermal and acoustic insulation as well as mechanical resistance are improved, but water absorption increases excessively (up to 400% of weight)
Solution Approach 1:
Hydrophobic agents act as intermediaries between the hydrophilic plant-based aggregates and the mortar matrix. These agents coat the surface of hemp shives or wood fibers, creating a water-repelling barrier that prevents excessive water absorption while maintaining the thermal and acoustic insulation properties of the plant materials.
Solution Approach 2:
The invention modifies the surface properties of plant-based aggregates by changing their hydrophilicity parameter. Through treatment with hydrophobic agents or selection of specific plant materials with naturally lower water absorption, the parameter of water uptake is altered to be compatible with hydraulic binders, reducing absorption from 400% to manageable levels.
2Temperature
If plant-based aggregates are used in hydraulic mortars, then insulation properties are improved, but setting consistency deteriorates due to variable water absorption
Solution Approach 1:
Hydrophobic treatments on plant aggregates serve as intermediaries that stabilize the interaction between the organic material and hydraulic binder. This consistent surface treatment ensures predictable water absorption behavior, leading to uniform setting times and improved manufacturing precision across different batches of hemp or wood-based mortars.
Solution Approach 2:
By controlling and standardizing the water absorption parameter of plant-based aggregates through preprocessing or chemical treatment, the invention achieves consistent setting behavior. This parameter control allows for reliable formulation of hydraulic mortars with plant aggregates, ensuring reproducible setting times and mechanical development.
3Strength
If conventional mineral binders are used with plant-based aggregates, then structural strength is achieved, but setting is delayed or inhibited due to interactions with extractives and degradation products
Solution Approach 1:
The invention introduces intermediary substances or surface treatments on plant-based aggregates that prevent adverse chemical interactions between extractives/degradation products and conventional mineral binders. This intermediary layer allows the binder to set normally by blocking the harmful chemical reactions that would otherwise delay or inhibit setting, while still maintaining structural strength.
4Ease of operation
If larger quantities of water are added to compensate for plant aggregate absorption, then workability is improved, but drying defects and chalking increase
Solution Approach 1:
Hydrophobic agents on plant aggregate surfaces act as intermediaries that control water distribution in the mortar. They allow sufficient water to be available for workability during mixing and application, while preventing excessive water retention in the plant material that would cause drying defects and chalking. This intermediary function enables reduced water content compared to untreated plant-based mortars.
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 solution enhances the setting process, reduces chalking, and increases mechanical resistance of hemp and wood-based materials without altering their functional properties, allowing for reduced binder quantities and lower costs.
Implementation Method 1
the binder composition has a specific surface area calculated according to the BET method greater than 10 m2/g
Implementation Method 2
A binder composition with a specific surface area greater than 10 m²/g, comprising powdered hydrated lime and colloidal clays, is used to enhance interaction with organic additives
Data Source
AI summary
The invention relates to a system of plant or bio-sourced materials selected among coatings, mortars and concretes of bio-sourced materials including a plant or bio-sourced material selected from the group that consists of wood and hemp, and a binder composition including a first conventional mineral component and a second component, said system being characterised in that said binder composition has a specific surface, calculated according to the BET method, that is greater than 10 m2/g, preferably greater than 12 m2/g, in particular greater than 14 m2/g, and the uses thereof.