Block Copolymer Dispersants for Alkaline-Activated Binders
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Solution Overview
Problem
Cement production using latent hydraulic and pozzolanic additives results in prolonged setting times, negatively affecting early strength, and existing dispersants like polycarboxylate-based comb polymers lose effectiveness in alkaline-activated binder compositions due to sensitivity to alkaline conditions.
Innovation Solution
The use of a block copolymer with specific monomer unit distributions and molecular weights, ensuring minimal monomer units in each block, provides effective dispersing properties even in alkaline-activated binder compositions, maintaining dispersing ability over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If polycarboxylate-based comb polymers are used as dispersants, then workability is improved and water/binder ratio is reduced, but effectiveness is lost after short time due to sensitivity to alkaline conditions
Solution Approach 1:
The patent changes the chemical structure parameters of the dispersant from comb polymer to block copolymer with specific monomer units (carboxylate groups in blocks rather than side chains), which fundamentally alters the polymer's resistance to alkaline conditions while maintaining dispersing capability
Solution Approach 2:
The invention uses a copolymer composed of at least two different monomer units (M1 and M2) with specific functional groups, creating a composite molecular structure that combines the dispersing properties of carboxylate groups with the stability of a block copolymer architecture resistant to alkaline degradation
2Object-generated harmful factors
If latent hydraulic and pozzolanic additives are used to replace cement, then CO2 emissions are reduced, but setting time is significantly prolonged
Solution Approach 1:
The block copolymer acts as an intermediary substance that facilitates the interaction between alkaline activating agents and latent hydraulic/pozzolanic additives, enhancing the activation process and accelerating setting time while maintaining the environmental benefits of using these additives
3Ease of operation
If water/binder ratio is reduced to improve workability, then processability is improved, but dispersing agent effectiveness is compromised under alkaline conditions
Solution Approach 1:
The invention changes the chemical composition parameters of the dispersing agent to use block copolymer structures with specific monomer ratios and functional group distributions, which maintain effective dispersing performance even at low water/binder ratios in alkaline-activated binder compositions
Data Source
AI summary
The invention relates to a block copolymer for use as a dispersant for mineral binder compositions, containing an alkali activating agent. Said block copolymer comprises at least one first block A and at least one second block B, the first block A containing a monomeric unit M1 and the second block B containing a monomeric unit M2. A proportion of monomeric units M2, if any, in the first block A is less than 25 mol %, in particular less than or equal to 10 mol %, relative to all the monomeric units M1 in the first block A, and a proportion of monomeric units M1, if any, in the second block B is less than 25 mol %, in particular less than or equal to 10 mol %, relative to all the monomeric units M2 in the second block B.