What is the quality control of micro-silica engineering construction?
Aug 02, 2024
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1. Requirements for cement
The selection of cement is the basis of the production and construction of the whole micro-silica powder project. The cement selected by micro-silica powder should have the characteristics of good activity, small water consumption of standard consistency, good adaptability between cement and admixture, and uniform color of raw materials. It is recommended to choose P.O.42.5R ordinary silicate low-alkali cement, requiring the same batch of clinker.
2, aggregate requirements
The principle of coarse aggregate selection is high strength, good continuous gradation of silica fume, low chemical activity, and the same color gravel, origin, specifications, must be consistent, and the mud content is less than 2%, the pure mud content greater than 5mm is less than 0.5%, and the aggregate shall not bring debris. Fine aggregate selection of coarse sand, the fineness modulus must be above 2.5, the color is consistent, its mud content should be controlled within 2%, greater than 5mm pure mud content is less than 1%. The stone is machine crushed stone, the particle size is 25mm, the sand is medium sand, and the fineness modulus is 2.7.
3. Requirements for admixtures
The selected admixture must have obvious water reduction effect and can meet the working performance of micro-silicon powder, and the admixture should be used as an efficient pumping agent.
4, ultrafine admixture requirements
The admixture should enhance the workability of micro-silica powder, partially replace cement, improve the construction performance of micro-silica powder, reduce the number and distribution of pores in cement stone, and help to inhibit the alkali-aggregate activity, which is conducive to improving the durability of micro-silica powder. The main properties of micro-silica powder should conform to the national standard "Technical Regulations for the Application of micro-silica powder of fly Ash".
5, the requirements of the slump of commercial micro-silicon powder
The micro-silica powder pouring is mainly poured by automobile pump and supplemented by tower crane. In order to ensure the smooth pumping, the slump when entering the pump is strictly controlled at 18cm to 13cm. Micro-silica mixing plant according to the temperature conditions, transportation time (day or night), transportation road distance, sand and stone moisture content change, micro-silica slump loss, etc., timely and appropriate fine-tuning of the original mix ratio (water-glue ratio) to ensure that the slump of micro-silica powder pouring can meet the needs of construction and production, micro-silica powder does not leak, not segregate, and the color is consistent. Ensure the quality of microsilica powder supply.
6. Requirements for the workability of micro-silica powder
In order to ensure that the micro-silica powder is not isolated during the pouring process, it is required that the micro-silica powder should have sufficient cohesiveness, and no bleeding and segregation during the pumping process. The "Technical Regulations for the construction of micro-silicon Powder Pumping" stipulates that the relative pressure bleeding rate of micro-silicon powder pumped for 10s shall not exceed 40%, so the micro-silicon powder bleeding rate supplied by the mixing station is required to be slow to ensure the stability and pumpability of micro-silicon powder.
7. Requirements for the initial setting time of micro-silicon powder
In order to ensure that there is no cold crack in the casting of micro-silica powder, according to the current climate, the initial setting time of commercial micro-silica powder during the construction of the structure is required to be ensured at 6-8h. When the climate changes, the micro silicon powder mixing station is required to provide the collapse loss value at different temperatures and per unit time, so that the site can master the stopping time of the micro silicon powder tank truck at the site, and when the micro silicon powder is poured, the mixing station should send a dispatch site deployment vehicle to adjust the frequency of the micro silicon powder tank truck at any time according to the micro silicon powder pouring situation.
8. Micro-silicon powder inspection requirements
Strict implementation of micro-silicon powder delivery inspection system. Micro-silicon powder by the commercial micro-silicon powder mixing station personnel to the on-site micro-silicon powder foreman assigned personnel, the content of the inspection includes visual inspection of the appearance of micro-silicon powder color, whether there is bleeding segregation, the experimenter to sample the slump of each car, whether it meets the technical requirements of the commercial micro-silicon powder receipt, and make a record. In case of slump greater than 18 and less than 13 cm of micro silicon powder must be returned to the mixing station, strictly prohibited use.
