Polükarboksülaate

Polükarboksülaate, more commonly known as polycarboxylates, are a class of superplasticizers extensively used in the construction industry, particularly in concrete admixtures. These synthetic polymers are characterized by a main chain with numerous pendant carboxylate groups. The unique molecular structure of polycarboxylates allows them to effectively disperse cement particles in concrete mixtures. This dispersion mechanism is primarily electrostatic repulsion and steric hindrance, where the charged carboxylate groups repel each other and the polymer chains physically prevent particles from agglomerating. This leads to a significant increase in the workability or flowability of fresh concrete without the need for additional water, a property known as water reduction. The ability to reduce water content while maintaining or improving workability results in higher compressive strength and increased durability of the hardened concrete. Polycarboxylate superplasticizers are available in various forms, with their effectiveness and performance influenced by factors such as the length of the main chain, the density and length of the side chains, and the specific chemical composition of the carboxylate groups. Their widespread adoption is due to their superior performance compared to older generations of superplasticizers like lignosulfonates and naphthalene sulfonates.