The working principle of concrete retarder

The working principle of concrete retarder

(1) Dispersion: After the cement is mixed with water, due to the hydration of the cement particles, the cement particles form an electric double-layer structure, which makes it form a solvated water film. The surface of the cement particles has an opposite charge to cause the cement particles to produce. The association effect makes the cement slurry form a flocculating structure, so that 10%-30% of the mixing water is wrapped in the cement particles, which cannot participate in free flow and lubrication, thus affecting the fluidity of the concrete mixture. 

When the concrete retarder is added, because the concrete retarder molecules can be adsorbed on the surface of the cement particles, the surface of the cement particles is charged with the same electric charge (usually negative charge), which forms electrostatic repulsion and promotes the mutual dispersion of cement particles and the disintegration of the flocculation structure. It releases part of the water that is wrapped and participates in the flow, thereby effectively increasing the fluidity of the concrete mixture.

(2) Lubrication: The hydrophilic group in the water reducer is very polar, so the concrete retarder adsorption film on the surface of the cement particles can form a stable solvated water film with water molecules, which has a good water film. The lubrication effect can effectively reduce the sliding resistance between cement particles, thereby further improving the fluidity of concrete.

(3) Steric hindrance: the hydrophilic branch in the structure of the concrete retarder agent stretches in the aqueous solution to form a hydrophilic three-dimensional adsorption layer with a certain thickness on the surface of the adsorbed cement particles. When the cement particles are close, the adsorption layer starts to overlap, that is, steric hindrance is generated between the cement particles. The more overlap, the greater the steric hindrance repulsion, and the greater the obstacle to the cohesion between the cement particles, which makes the concrete slump. The degree is maintained well.

(4) The slow-release effect of graft copolymerization branched chain: In the preparation process of new water-reducing agents such as polycarboxylic acid water reducing agent, some branches are grafted on the molecule of the water reducing agent, and the branched-chain can not only Provide steric hindrance. Besides, in the high alkalinity environment of cement hydration, the branch can be slowly cut to release polycarboxylic acid with dispersing effect, which can improve the dispersion effect of cement particles. And control the slump loss.

And, TRUNNANO provides high purity concrete retarder with reasonable price. “In order to feedback to old customers, the company is still in full operations to provide concrete retarder with competitive price.” said Olina, sales manager of TRUNNANO.

About TRUNNANO

TRUNNANO (aka. Luoyang Tongrun Nano Technology Co. Ltd.) is a trusted global chemical material supplier & manufacturer with over 12 years experience in providing super high-quality concrete retarder. As a leading nanotechnology development and concrete retarder manufacturer, Luoyang Tongrun dominates the market. Our professional work team provides perfect solutions to help improve the efficiency of various industries, create value, and easily cope with various challenges. If you are looking for concrete retarder, please send an email to: sales1@nanotrun.com.

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