1) automatic spray curing
(1) Sanitary water supply and circulation
In order to improve the utilization rate of healthy water, the edge of the pedestal forms a slope of 2%-4%, which is connected with the drainage ditch and reservoir to make healthy water circulate. Then, two submersible pumps are installed to pump water to the water tower near the prefabrication yard, and an automatic pumping device is installed on the water tower to keep the water in the water tower at the same level all the time and ensure the supply of sanitary water.
(2) Pipeline installation
The main pipe from the water tower to each row of bases is galvanized pipe with a diameter of 38mm, and a pipeline booster pump is installed. At the end of each row of pedestals, a galvanized pipe with a diameter of 25mm is set to communicate with the main pipeline, a gate valve with a diameter of 19mm is installed on each pedestal, and plastic hoses are connected to both sides of the web and the top plate.
(3) Maintenance of lower wing plate and web plate
A PPR pipe with a diameter of 19mm is set on both sides of the web of each beam to connect with the plastic hose. The PPR pipe has a nozzle every 1 m, and a PPR tee with a diameter of 19mm is installed at the nozzle, which is then connected with a 5cm long internal connector, 13mm ball valve and 65438+.
(4) Maintenance of beam top
For beam top maintenance, PVC pipes with a diameter of 19 mm are used, and a small hole is drilled every 10cm, which is arranged at the high side of Liang Chao to let water flow over the beam top surface, which not only reduces the labor intensity of maintenance, but also keeps the concrete surface moist all the time, thus achieving the maintenance effect.
2) Steam curing
Steam curing technology is adopted in winter construction of precast beams to accelerate the growth of concrete strength and elastic modulus. Boiler technical parameters and supporting facilities are selected according to the scale of health maintenance.
The steam curing process of concrete generally includes four stages: static stop, heating, constant temperature and cooling. The static stop stage refers to the stage from the completion of concrete pouring to the temperature rise at room temperature, which generally takes 2 ~ 6 h, which can enhance the ability of concrete to resist structural damage in the temperature rise stage; The heating stage refers to the stage when concrete rises from room temperature to constant temperature. In order to avoid cracks on the concrete surface caused by rapid temperature rise and volume expansion, the heating rate should be controlled within15℃/h; Constant temperature stage is the fastest growth stage of concrete strength, and the time to keep constant temperature is generally 48 ~ 72 h, which is related to the variety of cement in concrete, and the curing temperature of ordinary portland cement should not exceed 60℃. In the cooling stage, the concrete has hardened. If it is cooled too fast, surface cracks will appear in concrete. Therefore, the general cooling rate should be controlled at ≯10℃/h.
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