Introduction
Naphthalene based superplasticizers (NBS) dominate 67% of the high-efficiency water reducer market globally. These chloride-free admixtures enhance concrete workability while reducing water content by over 20%. Yet misconceptions about their performance persist, hindering optimal use in construction projects. This article separates fact from fiction surrounding NBS.

Myth 1: NBS Compromises Concrete Strength Over Time
Many contractors believe adding superplasticizers weakens long-term concrete strength. This couldn’t be further from the truth. NBS works by adsorbing onto cement particles, creating electrostatic repulsion that disperses agglomerates effectively. This mechanism allows better water distribution without diluting the mix.
Field data confirms properly dosed NBS improves both early and ultimate strength. In precast applications, NBS-enhanced concrete shows 15-20% higher compressive strength at 28 days compared to conventional mixes. The key lies in controlled water reduction—typically 15-30%—that increases density without sacrificing workability.

Myth 2: NBS Poses Severe Health and Environmental Risks
A common fear links NBS to toxic emissions and hazardous classification. Modern production methods disprove this. Today’s NBS contains less than 3% sodium sulfate, with advanced facilities achieving levels below 0.4%. Regulatory bodies classify NBS as non-hazardous under global standards.
While trace formaldehyde exists in production byproducts, concentrations are too low to pose risks. Proper ventilation during mixing eliminates residual odors, which workers often mistake for toxicity. Unlike some chemical admixtures, NBS doesn’t leach harmful substances into soil or water post-curing.

Myth 3: NBS Fails With Low-Alkali and Supplementary Cements
Contractors frequently avoid NBS with low-alkali cement, assuming incompatibility. Recent studies show successful use with proper adjustment. Low-alkali cement adsorbs NBS more rapidly, causing potential slump loss. This issue resolves by optimizing dosage or adding alkali sulfates to regulate adsorption.
NBS also works effectively with supplementary cementitious materials (SCMs). When used with fly ash or slag, it improves dispersion of all cementitious particles. The secret lies in testing mix proportions—slightly higher NBS dosages (1-2% by cement weight) often balance SCM interactions.

Myth 4: Higher Dosage Always Means Better Workability
More isn’t always better with NBS. Exceeding recommended dosages (typically 0.5-2% of cement weight) causes segregation and bleeding. The concrete loses cohesion as excessive superplasticizer reduces interparticle friction beyond optimal levels.
Laboratory tests demonstrate a clear dosage threshold. Once surpassed, workability declines rapidly despite increased water reduction. Contractors should follow manufacturer guidelines and conduct slump tests to find the perfect balance for each mix design.

Myth 5: All Superplasticizers Perform Equally; NBS Offers No Advantages
This myth ignores NBS’s unique benefits in specific conditions. Unlike polycarboxylate superplasticizers, NBS maintains performance in high-temperature environments. Its chemical structure resists breakdown at temperatures above 30°C, making it ideal for hot-climate construction.
NBS also provides superior slump retention compared to melamine-based alternatives. In tropical conditions, NBS mixes retain workability up to 60 minutes longer, reducing placement pressures during peak temperatures. These advantages explain NBS’s continued dominance in warmer regions.
Fact: NBS Meets Stringent Industry Standards
ASTM C 494 Type F certification ensures NBS products meet rigorous performance criteria. This includes consistent water reduction, minimal air entrainment (1-2%), and controlled setting times. Conforming products undergo testing for strength development, shrinkage, and compatibility with various cement types.
Modern NBS formulations even address historical limitations. New beta-naphthalene sulfonate condensates offer melamine-like early strength gains while maintaining NBS’s signature workability retention. These innovations expand NBS applications in time-sensitive projects.

บทสรุป
Naphthalene based superplasticizers remain valuable tools in modern construction when used correctly. Dispelling these myths reveals NBS as a safe, effective admixture that enhances strength, workability, and versatility. By understanding its properties and limitations, contractors can maximize NBS benefits in diverse concrete applications.
The next time you consider concrete additives, remember: properly applied NBS doesn’t just meet performance expectations—it exceeds them.