Sodium Naphthalene Sulfonate Formaldehyde Condensate Application

Sodium Naphthalene Sulfonate Formaldehyde Condensate Application

Sodium Naphthalene Sulfonate Formaldehyde Condensate is abbreviated as SNF. It has been an important
anionic surfactant in industry. It has been widely used in printing and dyeing, leather making, cement,
rubber, paint, oil field mud treatment and other industries. With the dramatic increase of synthetic fibers,
as the main additives of synthetic fibers dyes, the demand for naphthalene sulfonic acid formaldehyde
condensate has increased dramatically, and its position in the additive industry has become more
important.

Sodium Naphthalene Sulfonate Formaldehyde Condensate as Dispersing admixtures

Dispersing admixtures are the most important admixture type, accounting for over 60% of all admixtures sold in the UK. They include the types covered by the names Plasticizer, Superplasticizer, Water Reducer, High Range Water Reducer and they are covered by Standards EN 934-2 or by ASTM C494. Marketing ploys by admixture companies have introduced additional/alternative names including Mid-range, first, second and third generation, hyperplasticizer, etc. However, these names are generally not recognized by standards.

These dispersing admixtures all function by adsorption onto the cement surface in a way that causes the cement particles to distribute more uniformly throughout the aqueous phase, reducing the yield value for a given water content and so increasing the fluidity of the mix. They may also have a small effect on the plastic viscosity or cohesion of the mix. They are used in one or more of the following ways.

To increase the fluidity of the mix at a given water content. (Plasticizing or superplasticizing action)•

To reduce the water content of the mix at a given fluidity, improving strength and durability. (Water reducing or High Range Water Reducing).

To reduce the cement content by reducing water and maintaining water:cement ratio to give equivalent strength. (Cement reducing) In optimizing a concrete mix for a given application it will often be effective to use a combination of these properties (for example, to use the admixture at a dosage which can reduce the water content but also allow the fluidity of the mix to increase).

Dispersing admixtures fall into to two groups which, for standards purposes (EN 934 or ASTM C494), are divided by their water-reducing ability. These are the Normal Plasticizers/Water reducers and the Superplasticizers/High Range Water reducers.

Sodium Naphthalene Sulfonate Formaldehyde Condensate as Superplasticizers

Definition: water reduction more than 12% but depending on dose and type can give over 30%.

Other characteristics:•

Dosage, typically 0.6 to 2.0% on cement (30–40% soln).•

Minimal retardation except at the top of the dosage range.•

Synthetic chemicals derived from the chemical industry and designed with properties optimized specifically for admixture applications. There are currently three main chemical types: the sulphonated polymers of naphthalene or melamine formaldehyde condensates and the polycarboxylate ethers. These will be discussed in more detail later in this section.

These basic chemicals can be used alone or blended with each other or with lignosulphonate to give admixtures with a wide range of rheological properties. They can also be blended with other chemicals to increase retardation, workability retention, air entrainment and other properties.

Superplasticizers are a versatile group of admixtures with a wide range of potential properties and dosages, tailored to meet specific requirements. Dual-function products that are designed to give, say, water reduction and retardation are common, especially in warmer climates. It is therefore essential to check with the data sheet and the manufacturer before moving from one type or brand of superplasticizer to another.

Superplasticizers find use in the pre-cast and readymix concrete industries as well as in site-mixed concrete. In pre-cast they are used mainly as water reducers to give high early strength. On site-mixed they may be used:•

To give high workability where there is dense reinforcement•

For low water contents to give high early or later age strength•

For low w:c to give low-permeability durable concrete.

In readymix they are used for all the above applications and can also give extended workability to cope with long delivery and placing times, especially at elevated temperatures.

Superplasticizers are additions that allow a given degree of workability to be obtained at a reduced water/cement ratio. The ratio may be reduced by up to 20% in the presence of, for example, sulphonated naphthalene formaldehyde condensate, which is absorbed at the solid/liquid interface. They have the effect of neutralizing the surface attractions between individual particles of the cement, causing them to form a less open structure, which therefore requires less water to fill spaces and provide fluidity to the paste. By decreasing the water/cement ratio in this way, superplasticizers act to increase the strength of the cement product.

By the addition of both superplasticizers and microsilica, cements with a six-fold increase in tensile strength have been achieved.