Naphthalene series water-reducing agent can be divided into high-concentration products (Na2SO4 content <3%), medium-concentration products (Na2SO4 content 3%-10%) and low-concentration products (Na2SO4 content) according to the level of Na2SO4 content in their products. Content>10%). The water reducing rate of naphthalene water reducing agent is directly related to its dosage. In the past, since naphthalene-based water-reducing agent were mostly used in site mixing and were mainly mixed in powder form, people did not care about the content of Na2SO4 in the product. However, when the naphthalene-based water-reducing agent is supplied in liquid form, the low temperature (generally below 15oC) will cause Na2SO4 crystals in the product, which will seriously affect the metering and use effects. In order to reduce the degree of crystallization in the product and completely eliminate the phenomenon of crystallization, manufacturers generally use KOH, Ca(OH)2 instead of NaOH for neutralization, or increase the process of low-temperature suction filtration to remove Na2SO4. At present, most naphthalene-based water-reducing agent synthesis plants have the ability to control the content of Na2SO4 below 3%, and some advanced enterprises can even control it below 0.4%.

One of the disadvantages of naphthalene-based water-reducing agent is the compatibility with cement/admixtures, which are related to the degree of sulfonation, polymerization degree, neutralizing ion type, Na2SO4 content, and state of the water-reducing agent itself. , The dosage, the method of admixture, and the chemical composition of the cement/admixture, mineral composition, alkali content, gypsum form, and aluminate ratio, fineness and other factors.

The second disadvantage of the naphthalene-based water-reducing agent is that the slump loss of the concrete is faster after being added. Therefore, when used in commercial concrete, it is generally necessary to compound the retardation, air-entraining and other components to modify it to obtain the so-called pump Delivery products.

As an important type of water-reducing agent that has received wide attention, the structural feature of polycarboxylic acid-based water-reducing agent is that the hydrophobic main chain is aliphatic hydrocarbons, and the hydrophilic functional groups are connected to the side chains- SO3H, -COOH, -OH or polyoxyalkyl EO long side chain, etc.

The water-reducing performance of polycarboxylic acid-based water-reducing agents is related to the type of polymerized monomers selected and the composition of each block segment. This polymer electrolyte prepared by free radical solution polymerization can produce a greater dispersion effect under the condition of a small amount (0.1%-0.2%), and has excellent retardation, early strength or slump retention effects . The ethoxy chain on the polymer side chain is sometimes called a graft chain. This structural feature not only affects the water reduction rate, but also plays an important role in inhibiting the slump loss of concrete.

The polycarboxylic acid water reducer has a small amount of adsorption on the surface of cement particles, but because it has many branches, it can produce steric hindrance, so when the content is very low, a better plasticizing effect can be achieved. The presence of branch chains and the tooth-shaped adsorption method make it difficult for the initial cement hydration product to cover the adsorption layer of water-reducing agent molecules. Therefore, the effective time of the water-reducing agent on the surface of cement particles is longer. Compared with the commonly used naphthalene and melamine superplasticizers, polycarboxylic acid superplasticizers have the characteristics of low dosage, good reinforcement effect, good slump retention, and better adaptability to cement. The first choice for the preparation of low-water-binder ratio, high-strength and high-durability concrete.

Naphthalene series water-reducing agent can be divided into high-concentration products (Na2SO4 content <3%), medium-concentration products (Na2SO4 content 3%-10%) and low-concentration products (Na2SO4 content) according to the level of Na2SO4 content in their products. Content>10%). The water reducing rate of naphthalene water reducing agent is directly related to its dosage. In the past, since naphthalene-based water-reducing agent were mostly used in site mixing and were mainly mixed in powder form, people did not care about the content of Na2SO4 in the product. However, when the naphthalene-based water-reducing agent is supplied in liquid form, the low temperature (generally below 15oC) will cause Na2SO4 crystals in the product, which will seriously affect the metering and use effects. In order to reduce the degree of crystallization in the product and completely eliminate the phenomenon of crystallization, manufacturers generally use KOH, Ca(OH)2 instead of NaOH for neutralization, or increase the process of low-temperature suction filtration to remove Na2SO4. At present, most naphthalene-based water-reducing agent synthesis plants have the ability to control the content of Na2SO4 below 3%, and some advanced enterprises can even control it below 0.4%.

One of the disadvantages of naphthalene-based water-reducing agent is the compatibility with cement/admixtures, which are related to the degree of sulfonation, polymerization degree, neutralizing ion type, Na2SO4 content, and state of the water-reducing agent itself. , The dosage, the method of admixture, and the chemical composition of the cement/admixture, mineral composition, alkali content, gypsum form, and aluminate ratio, fineness and other factors.

The second disadvantage of the naphthalene-based water-reducing agent is that the slump loss of the concrete is faster after being added. Therefore, when used in commercial concrete, it is generally necessary to compound the retardation, air-entraining and other components to modify it to obtain the so-called pump Delivery products.

As an important type of water-reducing agent that has received wide attention, the structural feature of polycarboxylic acid-based water-reducing agent is that the hydrophobic main chain is aliphatic hydrocarbons, and the hydrophilic functional groups are connected to the side chains- SO3H, -COOH, -OH or polyoxyalkyl EO long side chain, etc.

The water-reducing performance of polycarboxylic acid-based water-reducing agents is related to the type of polymerized monomers selected and the composition of each block segment. This polymer electrolyte prepared by free radical solution polymerization can produce a greater dispersion effect under the condition of a small amount (0.1%-0.2%), and has excellent retardation, early strength or slump retention effects . The ethoxy chain on the polymer side chain is sometimes called a graft chain. This structural feature not only affects the water reduction rate, but also plays an important role in inhibiting the slump loss of concrete.

The polycarboxylic acid water reducer has a small amount of adsorption on the surface of cement particles, but because it has many branches, it can produce steric hindrance, so when the content is very low, a better plasticizing effect can be achieved. The presence of branch chains and the tooth-shaped adsorption method make it difficult for the initial cement hydration product to cover the adsorption layer of water-reducing agent molecules. Therefore, the effective time of the water-reducing agent on the surface of cement particles is longer. Compared with the commonly used naphthalene and melamine superplasticizers, polycarboxylic acid superplasticizers have the characteristics of low dosage, good reinforcement effect, good slump retention, and better adaptability to cement. The first choice for the preparation of low-water-binder ratio, high-strength and high-durability concrete.