Beijing Dongke United Technologies Co.,Ltd.

concrete plasticizer

Polycarboxylate ether

Polycarboxylic acid polymers have a significant retarding effect on cement, mainly due to the carboxyl group acting as a retarding component. R-COO~ interacts with Ca2+ ions to form complexes, reducing the concentration of Ca2+ ions in the solution and delaying Ca(OH 2) Form crystals, reduce the formation of CHS gel, and delay cement hydration.

The steric hindrance of the molecular chain of polycarboxylic acid (ie steric repulsion). Polycarboxylic acid molecules are adsorbed on the surface of cement particles in a “comb shape”, forming an adsorption layer on the surface of the gel material.

When the polymer molecular adsorption layers are close to each other and cross each other, a physical space hindrance is generated between the polymer molecular chains. Prevent the agglomeration of cement particles, which is an important reason why carboxylic acid type water reducers have stronger dispersing ability than other systems

The retention and dispersion mechanism of polycarboxylic acid superplasticizers can be understood from the relationship between the elapsed time after the cement slurry is mixed and the Zeta potential. Generally speaking, the slump loss of concrete using naphthalene series and melamine series superplasticizers after 60 minutes is significantly higher than that of concrete containing polycarboxylic acid series superplasticizers. This is mainly because the latter is different from the adsorption model of cement particles. The force of the polymer adsorption layer between cement particles is three-dimensional electrostatic repulsion, and the zeta potential changes little.

Good slump retention, basically no or little loss of slump within 90min; under the same fluidity, it has little effect on cement setting time, which can solve water reduction, air entrainment, retardation, bleeding, etc.

Problem: The polycarboxylate high-performance water-reducing agent can prepare super water-reducing agents with special properties and uses by adjusting the molecular structure, such as: low-temperature high-early strength type, zero slump loss type, shrink-resistant type, etc.

Using polycarboxylic acid type water reducing agent, more slag or fly ash can be used to replace cement, thereby reducing the cost; the source of raw materials for the synthetic polymer backbone is wide, and monomers usually include acrylic acid, methacrylic acid, and Malay Acid, ethyl (meth)acrylate, hydroxyethyl (meth)acrylate, sodium allyl sulfonate, methyl methacrylate, etc.; the molecular structure has a large degree of freedom, and the additive manufacturing technology has many controllable parameters , High performance potential; diversified polymerization methods, such as copolymerization, grafting, block, etc.

The synthesis process is relatively simple, since no harmful substances such as formaldehyde and naphthalene are used, it will not cause pollution to the environment.

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