The core purpose of maintenance

Reinforced concrete drainage pipes require curing to achieve strength growth after molding, while also preventing issues such as cracking and insufficient strength due to rapid water loss and excessive temperature changes. Proper curing ensures greater structural stability of the pipes, extends their service life, and guarantees their performance in drainage and sewage scenarios.

II. Main Maintenance Methods and Operation Standards

Steam Treatment (Common Efficient Method)

Steam curing accelerates the development of concrete strength by controlling temperature and humidity, making it suitable for scenarios with a fast production pace and specific requirements for the pipeline strength shaping cycle. The specific process is divided into four stages:

• Prenursery PhaseAfter molding, the pipes are left in the natural environment for 1-2 hours (in summer, this can be reduced to 30 minutes to 1 hour, and in winter, it can be extended to 2-3 hours). This stage allows the concrete to partially set, preventing sanding and peeling on the surface during subsequent heating, and also reducing cracks caused by the temperature difference inside and outside.

• Heating PhaseThe pipes are placed into a curing kiln, where the temperature is gradually increased at a rate of 10-15°C per hour. If the temperature rises too quickly, the moisture inside the concrete may evaporate too rapidly, leading to internal cracks and affecting the overall structure of the pipe.

• Maintaining Constant Temperature PhaseOnce the temperature reaches and stabilizes at 50-60℃; the duration of constant temperature is adjusted according to the pipe specifications. Generally, pipes with a diameter of 500mm or less are maintained for 4-6 hours, while those with a diameter greater than 500mm are kept for 6-8 hours. During the constant temperature period, ensure that the relative humidity inside the kiln is not less than 80% to allow for full hydration of the concrete and steady strength enhancement.

• Cooling PhaseReduce the kiln temperature slowly, maintaining a cooling rate of 10-15℃ per hour, until the kiln temperature difference with the external environment is no more than 20℃. Sudden temperature drops can cause concrete to expand and contract due to thermal expansion and contraction, leading to surface or internal cracking.

2. Natural Care (Low-Cost Basic Method)

Natural maintenance relies on temperature and humidity in the natural environment, is easy to operate, and is suitable for scenarios with a slower production pace and lower requirements for maintenance cycles. Key points include:

• Maintenance TimingAfter the pipe is demolded, the surface concrete can be cured once it has initially set (when gently pressed with a finger, no visible marks should appear). Typically, curing should begin within 2-4 hours after demolding.

• Moisture Retention MeasuresCover the pipeline surface with straw mats, burlap bags, and plastic film to ensure tight coverage and prevent rapid evaporation of moisture. After covering, water the area 3-4 times a day (increase to 5-6 times during summer heat and reduce to 1-2 times during winter) to keep the covering moist.

• Maintenance DurationThe natural curing duration must not be less than 7 days (it can be shortened to 5 days if a higher strength cement is used, but the concrete strength must exceed 70% of the designed strength). During the curing period, if rain occurs, the surrounding pipe area must be cleared of standing water promptly to prevent rainwater from weakening the bottom strength of the pipes.

III. Maintenance Precautions in Different Environments

Summer Maintenance

• High summer temperatures and rapid moisture evaporation require increasing the watering frequency to prevent coverings from drying out.

• If direct sunlight is intense, an additional sunshade cloth can be placed over the covering material to lower the surface temperature of the pipes, reducing concrete shrinkage cracks caused by high temperatures.

2. Winter Maintenance

• During the winter, with low temperatures and slow hydration rates of concrete, it is necessary to implement insulation measures. Rock wool blankets and thermal film can be wrapped around the coverings to ensure that the surrounding environment temperature of the pipeline does not drop below 5°C.

• If the environmental temperature drops below 0°C, heating equipment (such as a heater) should be set up in the maintenance area to prevent concrete from freezing; at the same time, reduce the frequency of watering to avoid water freezing on the pipeline surface and damaging the concrete structure.

3. Outdoor Storage Maintenance

• If pipes need to be temporarily stored outdoors before completion of curing and require natural curing, they must be properly covered and watered according to the natural curing requirements. Additionally, the pipes should be neatly stacked, with wooden boards placed between layers to prevent direct contact and surface wear.

• Storage sites must be level and well-drained to prevent rainwater from pooling and soaking the bottom of the pipes, affecting the maintenance effects.

Section IV: Maintenance Quality Inspection

• During the maintenance period, regularly observe the surface condition of the pipeline. If white spots, cracks, or sanding appear, adjust the maintenance measures promptly (such as increasing the frequency of watering, enhancing insulation, etc.).

• Following maintenance, the concrete surface strength was tested with a rebound meter to ensure it meets design requirements; simultaneously, the pipeline's appearance was inspected for any visible cracks or defects, and was deemed to have passed the maintenance.