Toluene diisocyanate manufacturer Knowledge The working principle of concrete water reducing agent

The working principle of concrete water reducing agent

Concrete water reducing agent is the most common water reducing agent. Since the 1940s, the design, planning and research of lignocellulosic water-reducing agents and various types of water-reducing agents with the same functions have been transformed. In the early 1960s, the first type of water-reducing agent was represented by naphthalene-based water-reducing agents. The third generation of high-efficiency water-reducing admixtures came out, and in the 1980s, the second-generation performance model water-reducing admixture represented by polycarboxylic acid-based water-reducing admixtures appeared. As an ideal upgrade product for third-generation water-reducing agents such as naphthalene series, the performance improvement of polycarboxylic acid-based high-efficiency water-reducing agents is comprehensive, and there are often qualitative leaps in terms of water-reducing effect and process performance. This article carefully compares the differences in water-reducing rates between naphthalene-based superplasticizers and polycarboxylic acid-based superplasticizers and their different impacts on concrete properties through experiments.

The water reduction rate of polycarboxylic acid-based water-reducing agents for Portland cement and general Portland cement is significantly better than that of naphthalene-based water-reducing agents. When the polycarboxylate water-reducing agent is used in Portland cement, it always has a significant water-reducing effect when the dosage is 0.5%. As the dosage increases, the water-reducing rate increases again, but when the dosage is increased to 1.0% The improvement in water-reducing effect is not necessarily obvious, but the water-reducing rate of naphthalene-based water-reducing agent still increases with the increase in dosage. When the polycarboxylic acid-based water-reducing agent is used in ordinary Portland cement, the water-reducing rate increases with the increase in the dosage. After the dosage exceeds 1.6%, the increase tends to slow down. The water-reducing rate of the naphthalene-based water-reducing agent increases with the dosage. The dosage increases but the slowness increases.

Specifically, the water-reducing rate of polycarboxylic acid-based water-reducing agents is much higher than that of naphthalene-based water-reducing agents, and is used in general Portland cement. It can achieve a much higher water reduction rate than that used for Portland cement.

(1) The water-reducing effect of polycarboxylic acid-based water-reducing agent is significantly better than that of naphthalene-based water-reducing agent. When the polycarboxylic acid-based water-reducing agent is used in Portland cement, the increase in water-reducing rate tends to slow down after the dosage is increased to 1.0%; when the polycarboxylic acid-based water-reducing agent is used in ordinary Portland cement, the dosage increases. After reaching 1.6%, the increase in water reduction rate tends to slow down.

(2) The addition of polycarboxylic acid-based water-reducing agents and naphthalene-based water-reducing agents is beneficial to improving the tensile strength of concrete at different ages. .

(3) Both polycarboxylic acid-based water-reducing agents and naphthalene-based water-reducing agents can improve the waterproofing, cold resistance and carbonization resistance of concrete. , listing the two effects as equal in improving cold resistance; for improving the waterproof concrete property and carbonization resistance, the effect of polycarboxylate water-reducing agent is more obvious.

(4) Polycarboxylic acid-based water-reducing agent is beneficial to reducing the shrinkage value of concrete, and can have a very good effect on improving the volumetric reliability, and mixed with The final shrinkage value of concrete containing naphthalene-based superplasticizer exceeds that of standard concrete and cannot have the effect of reducing shrinkage.

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