How to Make Cement for Prefabricated Houses

The production and application of cement for prefabricated houses mainly involve two core processes: cement preparation and concrete construction.

Cement Preparation Process

1. Raw Material Selection and Proportioning
   Ordinary Portland cement P.O42.5 is commonly used, which has an appropriate setting time and stable later-stage strength. The basic raw materials are limestone and clay, which are mixed in specific proportions before moving on to the next step. Limestone provides calcium components, while clay supplements oxides such as silicon and aluminum. Together, they form the main chemical composition of cement clinker.

2. Raw Meal Preparation
   The mixed raw materials are crushed into fine particles by a crusher and then subjected to pre-homogenization technology to ensure uniform composition. Subsequently, they enter a ball mill for grinding, forming raw meal powder with uniform particle size. This process requires strict control of the grinding time and fineness to ensure the adequacy of subsequent calcination reactions.

3. Clinker Burning
   The raw meal powder undergoes high-temperature calcination (about 1450°C) in a rotary kiln, undergoing complex physical and chemical changes. First, intermediate products in a semi-molten state are generated, which further react to form clinker minerals mainly consisting of tricalcium silicate (C₃S) and dicalcium silicate (C₂S). The cooled clinker is in the form of black granules and needs to be rapidly cooled to prevent crystal transformation from affecting its performance.

4. Cement Grinding
   The clinker, along with an appropriate amount of gypsum (to adjust the setting time), enters a ball mill for grinding, ultimately yielding cement products with a fineness that meets the standard. The grinding process requires control of the specific surface area, usually requiring it to be ≥300m²/kg to ensure the reactivity of the cement with water.

Key Points of Concrete Construction

1. Steel Reinforcement Framework Installation
   Before pouring, the steel reinforcement framework should be installed according to design requirements and fixed by binding or welding. The specifications, spacing, and anchorage length of the steel bars should meet the structural force requirements, forming an effective tensile load-bearing system.

2. Concrete Mixing
   A forced-action mixer is used to mix cement, sand, gravel, and water, with the water-cement ratio strictly controlled between 0.45 and 0.5. Too low a ratio will result in insufficient fluidity, while too high a ratio may cause segregation or a decrease in strength. If necessary, water-reducing agents can be added to improve workability.

3. Pouring and Curing
   The concrete should be vibrated and compacted in layers to avoid defects such as honeycombs and pits. After pouring, it should be immediately covered for moisture-retaining curing. At normal temperatures, the strength can reach 70% of the design value in 7 days and fully meet the standard in 28 days. During winter construction, insulation measures should be taken to prevent frost damage from affecting strength development.

Through the above process control, cement products for prefabricated houses can achieve high strength, durability, and dimensional stability, meeting the needs of modern building industrialization.