Condensed Aluminum Phosphate And Potassium Sodium Silicate For Potassium Sodium Silicate Cement

Condensed aluminum phosphate and potassium sodium silicate for potassium sodium silicate cement

1.Usage:

After the condensed aluminum phosphate contacts with potassium water glass, a double hydrolysis reaction occurs, which promotes the precipitation of colloidal silicon dioxide from potassium silicate, bonds the acid-resistant powder and gradually dehydrates and solidifies to form potassium water glass cement. According to a large number of engineering tests, the reaction rate of condensed aluminum phosphate and water glass is as high as 98%. The reaction rate of sodium fluorosilicate with water glass is only about 70%. The cement prepared with condensed aluminum phosphate as curing agent has high bonding strength, good compactness, high impermeability grade and strong acid resistance. Condensed aluminum phosphate is an inorganic high molecular polymer. The molecular chain length also gives the cement strong impact toughness. However, the cement prepared with sodium fluorosilicate as the curing agent is easy to form water-bearing crystalline salt (such as sodium salt) to destroy the colloidal structure, resulting in a decrease in the bonding strength and corrosion resistance of the finished product, which affects the quality of the project.

2.Applications:

The curing mechanism and curing factors of potassium water glass materials

The curing of potassium water glass materials is mainly a chemical reaction between potassium water glass (potassium silicate) and condensed aluminum phosphate, and the reaction is carried out step by step:

The first step: the hydrolysis reaction of potassium water glass: potassium silicate undergoes a hydrolysis reaction to generate silicic acid gel and potassium hydroxide.

K 2 O﹒ nSiO 2 +(2n ＋ 1)H 2 O 2KOH+nSi (OH) 4

The second step: the reaction of potassium water glass and condensed aluminum phosphate: the condensed aluminum phosphate in the powder undergoes a hydrolysis reaction in the alkaline solution of potassium water glass to generate aluminum hydroxide and metaphosphoric acid.

Alm (PO 3) +3mH 2 O → mAl(OH) 3 +3mHPO 3

The generated metaphosphoric acid (HPO 3) and potassium hydroxide (KOH), the hydrolysate of potassium silicate, undergo a neutralization reaction, thus destroying the reversible balance of the potassium silicate solution and making the reaction proceed in the direction of generating silicic acid gel:

KOH + HPO 3 → KPO 3 +H 2 O

The third step: silicic acid gel dehydration condensation: the generated silicic acid gel [Si (OH) 4] bonds the acid-resistant and heat-resistant powders into a body, and the dehydration and condensation reaction continues to generate silica and form a network structure. Eventually leads to the curing of the material.

Si (OH) 4 → SiO 2 ＋ 2H 2 O

From the above reaction mechanism, the final step of water glass material solidification is the dehydration reaction of the material. Once the humidity in the air is high (such as rain and snow) and the moisture content in the air is high, the solidification of water glass material will be slow. Therefore, the environment (relative humidity, ventilation conditions, temperature) has a greater impact on the curing speed of potassium water glass. Other factors that affect the curing of potassium water glass materials include: the modulus of potassium water glass, the degree of condensation of condensed aluminum phosphate, the ratio of potassium water glass and condensed aluminum phosphate, and so on.

3.Aluminum phosphate chemical examination report: