Obtain the design report of high strength concrete mixture

Questions, methods, information, conclusions.

The three basic parameters in the design of concrete mix are:

1. Water-cement ratio, that is, the ratio between water and cement;

2. Sand rate, that is, the ratio between sand and gravel;

3. Unit water consumption, that is, the ratio between aggregate and cement slurry.

Once these three basic parameters are determined, the mix ratio of the concrete is also determined.

1.In the preliminary mix design stage, the preliminary mix ratio is determined according to the relationship between the preparation strength and the design strength, the calculation method of water-cement ratio, the method of checking the table of water quantity and sand rate, and the calculation method of sand and gravel materials.

2.In the design stage of the laboratory mix ratio, the mix ratio is adjusted according to the differences and changes in construction conditions and possible fluctuations in the quality of the material.

3.In the design stage of the benchmark mix ratio, the amount of material per cubic meter of concrete is determined according to the principle of strength verification and the density correction method.

4.In the design stage of the construction mix ratio, the mix ratio is adjusted according to the measured moisture content of sand and gravel, and the construction mix ratio is proposed.

Adjustment steps: set the laboratory mix ratio as: cement:

Water: Sand: Stone = 1:

x:y:z, the moisture content of the sand on site is m, and the moisture content of the stone is n, then the construction mix ratio is adjusted as:

1：(x-y*m-z*n)：y*(1+m)：

z*(1+n)。

Concrete mix design is a very important work in concrete engineering, which directly affects the smooth construction of concrete, the quality of concrete engineering and the cost of concrete engineering.

The so-called concrete construction mix ratio refers to the proportional relationship between the constituent materials in the concrete.

Adjustment steps: set the laboratory mix ratio as: cement:

Water: Sand: Stone = 1:

x:y:z, the moisture content of the sand on site is m, and the moisture content of the stone is n, then the construction mix ratio is adjusted as:

1：(x-y*m-z*n)：y*（1+m）：

z*（1+n）。

<> the selection of raw materials, because the amount of cement directly affects the amount of heat of hydration, large volume of concrete should be selected with low heat of hydration, such as low-heat slag Portland cement, medium-heat Portland cement, etc., and reduce the amount of cement as much as possible. Zone 2 medium sand should be used for fine aggregates, because the use of medium sand can reduce the amount of water and cement compared with fine sand. In the case of coarse aggregate that can be pumped, continuous graded stones with a particle size of 5-20 mm are selected to reduce the shrinkage and deformation of the coagulation and ballast soil.

Admixtures are used, and fly ash is added. The fly ash mixed in concrete can only save cement, reduce the heat of hydration, increase the workability of concrete, and greatly improve the strength of concrete in the later stage, and the time of the peak temperature rise can be passed.

Use of admixtures. Use superplasticizers, such as retarding high-efficiency superplasticizers; Expansion agents are used, such as the widely used U-shaped expansion agent, anhydrous calcium sulfuraluminate or aluminum sulfate. The test shows that the expansion stress generated in the concrete after the expansion agent is added to the concrete can offset the shrinkage stress of a part of the concrete, so that the crack resistance of the concrete can be improved accordingly.