What is steam curing of concrete

The lining maintenance is realized by covering the surface of freshly placed concrete lining with steam prepared by a boiler. The temperature and humidity needed to harden the concrete material are mainly provided by hot steam, and it is suitable for the construction of lining at the entrance and neck in winter in cold areas.

Concrete filling is completed after the start of the steam supply, the total time of maintenance and the project site, temperature conditions and cement varieties, etc., need to be adapted to local conditions by virtue of experience to determine.

According to the different steam pressure, can be divided into:

1, atmospheric pressure steam curing

2, no pressure steam curing

3, micro-pressure steam curing

4, high-pressure steam curing

Steam curing attention to

1, the steam pipe is shelved longitudinally laid, in the application of steam is not directly to the beam and the formwork. Template, to avoid local high temperature; in winter steam injection tube wrapped outside the special thermal insulation to ensure the normal supply of steam (i.e., made of tubular rigid foam wrapped in silver heat-returning cloth).

2, the success or failure of steam curing key is to control the process of temperature rise and fall, especially in the cooling phase, due to the high temperature of the concrete in the early compressive strength growth faster, but its tensile strength did not do the same proportion of growth, low strength.

If the cooling gradient is too large it is easy to produce a large temperature tensile stress in the concrete structure, resulting in cracks. Temperature difference control is crucial in the temperature rise and fall stage, by improving the conditions of steam conservation, strengthening the monitoring of steam conservation to ensure that the temperature gradient in the range of 10~15 degrees can effectively avoid the occurrence of cracks.

Extended information

Concrete winter maintenance methods and problems

1, coal-fired steam maintenance

This way in the process of generating steam, at the same time, produces a lot of harmful gases ( carbon dioxide, sulfur dioxide, nitrogen oxides) and PM2.5. Some larger precast girder yard, need to invest more money to build a steam boiler. Some larger prefabricated girder yards need to invest more money in the construction of steam boiler room and along the girder place where there is a pedestal arrangement of steam pipeline, steam pipeline delivery distance is too far also directly lead to the heat loss along the way, and the process of steam maintenance requires manual 24 h uninterrupted shifts.

2, honeycomb furnace heat conservation

This method is generally placed in the concrete covered with a number of small honeycomb furnace, heat storage and insulation through the heat generated by the burning coal furnace, which has no effect on the moisturizing, and in the combustion process produces more carbon monoxide gas, and carbon monoxide is in contact with the surface of the concrete will exacerbate the carbonation of the concrete, and at the same time, the presence of carbon monoxide in the curing shed cover on the entry of carbon monoxide, the carbon monoxide gas will be used in the curing shed cover. Existing in the conservation shed cover to enter the internal construction personnel there are greater security risks.

3, winter hot water conservation

This way is generally through the electric heating of water to a certain temperature and then sprayed on the surface of the concrete, there is a certain degree of heat preservation and moisturizing effect, but with the loss of water loss of heat loss fast, the surface of the concrete in some areas or storage of water, the heat supply is not timely, the temperature may drop when the ice.

4, electric steam curing

This way to generate steam through electric heat, no pollution, but in the construction process still need to be controlled by human start and stop, through manual measurement of maintenance of temperature and humidity to determine whether the supply of steam, and thus the quality of maintenance and the operator's responsibility is very large, especially at night to measure the temperature of the work and other difficult to implement, all the existence of a larger Limitations.

Baidu Encyclopedia - Steam Curing Concrete