How to Make Prefabricated House Cover Plates

The production of prefabricated house cover plates mainly includes five steps: preparing the mold, mixing ingredients, pouring concrete, curing, and removing the mold.

Preparing the mold: Select an appropriate mold according to the required shape and size of the cover plate. The mold must have sufficient strength and rigidity to ensure the accuracy and quality of the cover plate. Common mold materials include steel plates or dedicated plastic molds. Before use, check their flatness and sealing to prevent concrete leakage.

Mixing ingredients: Mix raw materials such as cement, sand, and gravel in the designed proportions, and add an appropriate amount of water and other additives (such as water reducers and early-strength agents) to obtain concrete with stable performance. During the mixing process, strictly control the water-cement ratio to ensure the workability and strength of the concrete. The mixing time is usually 2-3 minutes until the mixture is uniform and free of lumps.

Pouring concrete:

• Workers first form the steel plate into a mold, tighten the screws, and then spray a release agent to prevent the concrete from sticking to the mold.
• Lay the first layer of steel reinforcement framework (distribution bars), and then pour about 4 centimeters of concrete as the bottom layer.
• Place a 15-centimeter-thick giant foam board as a lightweight core material, fix its shape with iron hooks between the foam pieces, and then lay the second layer of steel reinforcement framework and thread steel strands (load-bearing bars).
• Adopt the pre-tensioning method, use dedicated equipment to pull the steel strands to their ultimate strength and fix them, then pour the second layer of concrete and vibrate it densely to ensure the concrete is filled densely without bubbles.
• Another common method is to directly pour the well-mixed concrete into the mold and vibrate it with a vibrating rod or vibration table to expel internal air and improve density.

Curing:

• After pouring, immediate curing is required to promote the development of concrete strength. Common methods include steam curing: send the cover plate to a basement for about 4 hours of steam "sauna", accelerate the hydration reaction through a high-temperature and high-humidity environment, and make the concrete harden quickly.
• Natural curing can also be used. Cover the surface of the cover plate with a moisture-retaining film or straw mat, maintain an ambient temperature of 15-25°C and a humidity of ≥90%, and the curing time should be no less than 7 days.

Removing the mold: After curing, remove the mold and trim the edges of the cover plate. Use an angle grinder to cut off the excess steel bars exposed at both ends to ensure the dimensions meet the design requirements. Avoid violent operations when removing the mold to prevent damage to the edges of the cover plate. The final prefabricated cover plate must undergo strength testing and can only be put into use after passing the test.