The Important Role of Aluminum Dihydrogen Phosphate in High Temperature Resistant Cement

One of the reasons for the collapse of the 110 - storey twin tower of the World Trade Center is that the top floors of the tower burned for nearly an hour after being hit by an airplane because the tower was saturated with aviation fuel. The high temperature of 800 ℃ caused the steel columns running through the building to bend and the unsupported concrete floor began to collapse.

One of the most common ways of concrete reinforcement is a composite material formed by adding steel bars, steel mesh, steel plates or fibers into concrete soil. The two work together to improve the mechanical properties of concrete with insufficient tensile strength. Generally, steel bars bear the tensile force and concrete bears the compressive stress. However, one of the main problems faced by super high-rise buildings is that when reinforced concrete buildings are exposed to fire, the steel bars become soft due to heat and the building's gravity is relatively large, which leads to the reduction of the performance of the whole reinforced concrete structure, thus the high temperature resistance of cement needs to be highlighted.

High temperature resistant cement develops rapidly and its varieties are increasing. It can be made into high temperature resistant concrete by mixing with refractory aggregate. China has now successfully developed concrete with aluminate cement, phosphate, water glass, magnesium cement and dolomite refractory cement as cementing agents.

High temperature resistant concrete is mainly used in petroleum, metallurgy, chemical industry, electric power, building materials and other departments.

Aluminate cement, phosphate, water glass and silicate cement refractory concrete are the four most widely used kilns and thermal equipment. High temperature resistant concrete uses the following types of binders: 1. Cement ( hydration ) binders: Portland cement, fast hardening Portland cement, high aluminum cement, etc. 2. Air hardening binder: sodium silicate and periclase cement. 3. Chemical binders: sodium silicate, phosphate and others.

Aluminate cement silicate cement

900 ℃ also has 70% of the original hardness, and 1300 ℃ keeps 53% of the hardness. Its high-temperature resistant concrete has a relatively low service temperature, up to 1400 ~ 1500 ℃

Phosphate cement

At present, the most commonly used refractory materials and aggregates used in orthophosphoric acid and aluminum dihydrogen phosphate refractory concrete are corundum mullite, siliceous clinker, zircon, etc. They are characterized by good thermal stability, high and stable compressive strength, high refractoriness under load, good impact resistance and high cost. Sodium silicate cement can be made into sodium silicate refractory concrete by cementing other aggregates with water glass. Sodium silicate itself is a good refractory property. Sodium silicate refractory concrete is generally used in projects below 1000 ℃

The cost of special cement is generally higher than ordinary cement, which is related to its raw materials and processing technology.

With the development of human society, the existing resources are less and less, and the requirements for rational utilization of resources, reduction of energy consumption per unit product and environmental protection will become higher and higher. Therefore, heat-resistant concrete and ultra-low cement fire-resistant and heat-resistant concrete soil will occupy an important position in concrete production in the future.