Principles for determining appropriate sand rate

Reasonable sand rate, good aggregate gradation and small void ratio can give concrete better workability, save cementitious material slurry, thereby improve the volume stability of concrete, and can provide a bonding surface between aggregate and cement stone. (sand crusher) improve the strength of concrete.

The principle of determining the appropriate sand rate is to ensure that the sand fills the gaps between the stones and there is a certain margin to form a mortar layer of a certain thickness between the stones to reduce the frictional resistance between the coarse aggregates and improve the fluidity of the mixture ( The sand rate when the slump T) reaches the maximum and the cohesion and water retention are good; or when the fluidity (slump T) and strength are constant and the cohesion is good, the sand rate is the minimum amount of cement. In layman's terms, that is, the sand rate should be determined by the gradation of coarse and fine aggregates. The ultimate goal is to obtain the smallest aggregate porosity and the best aggregate mix by adjusting the sand rate to reduce the need for slurry. .

Sand with different particle sizes needs to choose different sand rates. For sand with a lower fineness modulus, a lower sand rate should be chosen. For sand with a higher fineness modulus, a higher sand rate should be chosen, because the finer the sand, the lower the sand rate. The larger the surface area, the greater the amount of cementitious material that needs to be wrapped around the sand. Therefore, the sand rate must be reduced to ensure the strength and workability of concrete. On the contrary, the coarser the sand, the sand rate should be increased to ensure the workability of concrete.

Concrete for different uses also needs to choose different sand rates. For example, thin-walled components require a higher sand rate to ensure the strength and fluidity of concrete. Concrete with a lower strength level should choose a higher sand rate and a higher strength level. The concrete should choose a lower sand rate. There are also special construction methods such as pumped concrete, self-leveling concrete, shotcrete and roller compacted concrete, etc. The sand rate selection has its own particularities and should be selected according to the corresponding rules.

In addition, in addition to determining the reasonable sand rate based on the principles of fluidity and cement dosage, as well as the requirements for the cohesion and water retention of the concrete mixture based on the materials used and construction conditions, it is also necessary to consider the impact of admixtures, fibers and other materials on the sand. The influence of sand rate, and special tests are conducted to determine the optimal sand rate to ensure the quality and performance of concrete.

The sand rate is very important to the performance and economy of concrete. Therefore, in order to ensure that the final sand and gravel product meets the requirements, it is necessary to select the appropriate sand and gravel production line equipment, and configure and adjust the equipment parameters according to the appropriate sand rate to obtain different particle sizes. and graded sand and gravel.

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