In order to be in line with international standards, the Ministry of Construction and the General Administration of Quality Supervision, Inspection and Quarantine jointly issued the National Standard of People's Republic of China (PRC) GB/T5008 1-2002.

The new standard puts forward higher requirements for the temperature and humidity of the standard curing chamber in the original standard, from the original standard curing chamber with the temperature of 20 3℃ and the humidity greater than 95% to the temperature of 20 2℃ consistent with the ISO test method.

Extended data

Concrete preparation process

1, folding mashup design

When preparing concrete, first of all, according to the requirements of engineering for workability, strength and durability, the raw materials should be selected reasonably and the proportion should be determined to achieve the purpose of economy and application. The design of concrete mixture ratio is usually carried out according to the requirements of water-cement ratio method. The calculation of material consumption mainly adopts assumed bulk density method or absolute volume method.

2, concrete mixer

Concrete mixer: According to different construction requirements and conditions, concrete can be mixed at the construction site or mixing station. Self-falling mixer can be used for concrete mixture with good fluidity; The poor fluidity or hard concrete should be stirred by forced mixer. Before mixing, the ingredients should be mixed according to the requirements of mixture ratio to control the weighing error. The feeding sequence and mixing time have an influence on the quality of concrete, which should be strictly controlled to make the materials of each component mix evenly. ?

3, transportation and pouring

Transportation and pouring: concrete mixture can be transported to the construction site by hopper, belt conveyor or mixer. The dumping method can be manual or mechanical. It is efficient to transport and pour concrete mixture with concrete pump, which can reach hundreds of cubic meters per hour. Whether it is cast-in-place concrete engineering or prefabricated components, the compactness of concrete after pouring must be ensured.

Its method mainly adopts vibration tamping, and some also adopt centrifugation, extrusion and vacuum operation. Fluidized concrete mixed with some superplasticizers cannot be vibrated.

4. Maintenance

The purpose of curing is to create suitable temperature and humidity conditions to ensure or accelerate the normal hardening of concrete. Different curing methods have different effects on concrete performance. Common curing methods include natural curing, steam curing, dry-wet curing, autoclaving curing, electric heating curing, infrared curing and solar curing. The time of maintenance experience is called maintenance cycle.

In order to facilitate comparison, it is stipulated that the specimens for measuring concrete performance must be cured under standard conditions. The standard curing conditions adopted in China are: the temperature is 20 2℃; ; Humidity is not less than 95%.

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