Different molecular structures and action mechanisms
Polyacrylic-based water reducers have a comb-like molecular structure, with carboxyl groups on the main chain and polyether segments on the side chains. They have a dual dispersion mechanism of electrostatic repulsion and spatial steric hindrance. This structure helps the molecules form a "protective shell" on the surface of cement particles, effectively improving the dispersion ability and slump retention performance. Naphthalene-based water reducers are a traditional admixture, based on naphthalene sulfonic acid. Their dispersion principle mainly relies on electrostatic repulsion, and their molecular structure is relatively simple with a single function.
There are significant differences in water reduction rate and slump retention performance.
In terms of water reduction rate, polycarboxylate type water reducers usually perform better than naphthalene-based products. Their water reduction rate can reach 20% to 25%, and they show more stable performance in maintaining the fluidity of concrete. Even during long-term transportation or in high-temperature environments, the change in slump is relatively small. In contrast, the water reduction rate of naphthalene-based water reducers is usually between 10% and 15%, and the slump loss is relatively rapid, especially during summer construction, when workability problems are prone to occur.
There is a difference between environmental protection and green performance.
Polycarboxylate type water reducers are more in line with the standards of green building materials and environmentally friendly construction due to their low alkalinity, low odor, and low emission of volatile organic compounds. Especially in the context of the country's vigorous promotion of green buildings, their application prospects are very broad. Because naphthalene-based water reducers contain aromatic compounds, during use, trace amounts of organic volatile substances may be released, which may have certain impacts on the construction environment and personnel. Some products also have high alkalinity characteristics, which is not conducive to sustainable construction.
Different adaptability to applicable projects and construction conditions
Polymeric acid-based water reducers are suitable for various complex conditions, such as pumped concrete, high-performance concrete, self-compacting concrete, prefabricated components, etc., especially for harsh conditions like high strength and long-term operations. Naphthalene-based water reducers are more commonly used in general projects or cost-sensitive projects, such as ordinary commercial concrete, road infrastructure construction, etc. These projects have lower performance requirements.
Comparison of comprehensive costs and cost-effectiveness
From the perspective of raw materials, naphthalene-based water reducers have economic advantages in some projects because of their mature technology and lower cost. However, their performance is slightly inferior and they are easily affected by the type of cement and temperature. The synthesis process of polymeric acid-based water reducers is relatively complex and their prices are slightly higher, but they have high water reduction efficiency and stable construction performance. From the aspects of overall usage, performance improvement, and concrete durability, their unit strength cost is more competitive.
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