Casting Time of Prefabricated Cement Houses

The casting time of prefabricated cement houses needs to be comprehensively determined based on construction methods, seasonal conditions, and structural requirements, as detailed below:

I. Seasonal Construction Time Requirements

1. Summer Construction: Prioritize casting during periods of lower temperatures, such as from 5:00 AM to 10:00 AM or after 6:00 PM at night, to avoid rapid concrete setting and internal hydration heat accumulation that can cause cracks during high-temperature periods (e.g., noon). If daytime operations are necessary, take sun-shading and cooling measures, such as covering with thermal insulation cloth or mixing concrete with ice water to lower the initial temperature. When the daily maximum temperature exceeds 30°C, construction without cooling measures is strictly prohibited, as it can easily lead to insufficient concrete strength or surface cracking.
2. Winter Construction: The casting time should preferably be controlled between 9:00 AM and 4:00 PM when temperatures are relatively higher, facilitating the concrete hydration reaction. If the ambient temperature falls below -5°C, construction should be halted, as low temperatures significantly slow down concrete setting and can even cause frost damage, affecting structural safety.

II. Differences in Construction Cycles Among Different Prefabrication Technologies

1. Cement 'Prefabricated House' Technology: The main structure uses factory-prefabricated components, with on-site hoisting taking only about 4 hours. However, it requires coordination with foundation treatment (e.g., leveling and compaction) and subsequent decoration works, resulting in a relatively short overall cycle suitable for rapid construction needs.
2. Modular Cement House Technology: Standardized modules (e.g., walls and floor slabs) are prefabricated in the factory and assembled on-site using bolts or welding, with a typical construction cycle of 5 days. This method is suitable for temporary buildings or emergency housing.
3. Traditional Monolithic Casting Houses: Concrete needs to be continuously cast and formed, but it requires a 28-day curing period to achieve the design strength (C30 concrete requires an compressive strength of ≥30 MPa after 28 days of standard curing). During this period, a moist environment must be maintained (e.g., covering with plastic film or spraying water for curing) to prevent rapid moisture evaporation that can lead to strength loss, resulting in a longer overall cycle.

III. Casting Time Requirements for Structural Columns If the house design includes structural columns (used to enhance wall stability), the principle of 'wall construction before column casting' should be followed: After the wall is constructed and left to settle for 7 days, the structural column concrete can then be cast. This interval ensures wall settlement stability, avoiding cracks at the joint surface caused by differences in shrinkage rates between the masonry and concrete, thereby guaranteeing structural integrity.

Summary: The casting time should be flexibly adjusted based on seasonal temperatures, technology types, and structural requirements. Strict adherence to specifications can avoid quality hazards and extend the service life of the house.