What are the requirements for manufactured sand for concrete? Manufactured sand acts in concrete 15

On September 30, 2021, the C130 high-performance machine-made sand concrete (with strength) jointly developed by the New World Zengcheng Project of China Construction Eighth Engineering Bureau No. 1 Company, together with South China University of Technology, design firms, mixing plants and other units, was applied to engineering entities for the first time, pumping more than 220 meters, setting a precedent in Guangzhou and even the whole country.

As a super high-rise building, the maximum floor area of the New World Zengcheng Comprehensive Development Center project is 241 meters. Before pumping C130 concrete, the project has successfully pumped C80 concrete after hundreds of ratio tests, with a pumping height of more than 130 meters, a strength of 100MPa, and a cumulative pouring of 10,000 cubic meters, which greatly helped the project construction, enhanced the building strength, reduced the occupied area, and increased the building use area.

In December 2020, the project took the lead in setting up a C130 technology research and development team, with members including South China University of Technology, owners, and design firms, to jointly carry out C130 concrete research. Due to the design strength of C130, the strength exceeds C80 concrete, and the difficulty of research and development and pumping has also been greatly improved, after up to 10 months of joint research, C130 technical research and development team finally tried to match C130 concrete, and on September 30, it was successfully pumped and applied to the construction of super high-rise projects.

C130 high-strength concrete greatly reduces the area of concrete components and increases the usable area of the building, which is very suitable for the concept of improving the land utilization rate of super high-rise buildings, and can effectively save concrete and formwork and reduce labor.

1. On the issue of machine-made sand for concrete.

2. Standard catalogue of concrete raw materials, admixtures, concrete and mortar.

3. Research on Machine-made Sand Commercial Concrete Author: Deng Junyao, Bi Wanli, Bi Chongliang, Wang Xicai (Dalian Institute of Building Science and Design) Magazine Name: Concrete Year: 1993 Issue No.: No. 4.

Strength characteristics of artificial machine-made sand RCC".

Study on Pumping Concrete Technology under the Conditions of Machine-made Sand".

Development of ultra-high-strength and high-performance concrete with manufactured sand

Research on the preparation of C50 and C80 high-performance concrete from machine-made sand and slag powder

Experimental Research and Engineering Application of Machine-made Sand Pumping Concrete".

Experimental study on high-performance pumping concrete with C60 machine-made sand".

The sand that meets the standard of machine-made sand in the second area is most suitable for concrete, of course, stone powder, fineness modulus, etc. must meet the standard.

The requirement for the preparation of concrete sand is to use sand with small porosity and total surface area as much as possible.

The particle gradation of sand indicates the combination of sand size particles. The void between the sand particles in the concrete is filled by the cement slurry, and the void between the sand particles should be reduced as much as possible in order to achieve the purpose of saving cement and improving the strength.

If it is sand of the same coarseness, the void is the largest. When the two particle sizes of sand are combined, the void is reduced; With the combination of three particle sizes, the void is smaller. It can be seen that in order to reduce the void between the sand grains, it is necessary to have a combination of particles of different sizes.

The coarseness of sand refers to the overall coarseness of sand particles of different particle sizes after being mixed together, usually divided into coarse sand, medium sand and fine sand. Under the same quality conditions, the total surface area of fine sand is larger, while the total surface area of coarse sand is smaller.

In concrete, the surface of the sand needs to be wrapped by a grout, and the larger the total surface area of the sand, the more grout needs to be wrapped around the surface of the sand. Therefore, it is generally said that it is more economical to mix concrete with coarse sand than to use the cement slurry required with fine sand.

Therefore, these two factors (particle gradation and coarseness of the sand) should be considered at the same time when mixing concrete. When the sand contains more coarse-grained sand, and fills its void with appropriate medium-sized sand and a small amount of fine-grained sand, the porosity and total surface area can be smaller, and such sand is ideal, not only the amount of cement slurry is less, but also can improve the compactness and strength of concrete.

It can be seen that it is of great technical and economic significance to control the particle gradation and coarseness of sand, so they are important indicators to evaluate the quality of sand. The mere use of the gauge is not a criterion.

Coarse sand is generally better to use test-mixed high-grade concrete. It is better to test the medium sand below C30. This is based on my years of experience.

The requirement for configuring concrete sand is to use as much as possible. of sand.

Answer: 2 graded areas (medium sand).

The mud content in the river does not exceed 3% medium particles.

Try to use natural river sand or artificial fine sand.

The quality of sand in concrete has a great impact on the strength, compactness and durability of concrete. Natural river sand and artificial fine sand are usually the more used sand materials in concrete, which have the characteristics of uniform particle size, less mud content, less dust content, large particle hardness, and small angular edge, which can ensure the strength and compactness of concrete, and are not easy to cause cracks or leakage. In addition, the moisture content of these sands is generally low, which can effectively control the water-cement ratio of concrete and improve the quality of concrete.

In addition to natural river sand and artificial fine sand, there are some other sand materials that can also be used as concrete sand, such as mountain quartz sand, lakeside sand, etc. However, the quality and suitability of these sands can only be determined through experiments and testing. When choosing sand, it is necessary to choose according to the specific use of concrete, strength grade and environmental conditions.

Answer] :d principle of preparing sand for concrete is to hope that the sand has high density and small specific surface area, so that it can be simple to achieve the suitable workability, strength and durability of concrete, and to achieve the purpose of saving cement. Defeat stupidity.

Answer] :d requirement for the preparation of sand for commercial concrete is to use sand with small porosity and total surface area as much as possible. The sand used for mixing concrete should be coarsely leaked and buried, which can reduce the particle surface area of the sand, thereby reducing the amount of cement and returning to the chain.