16/05/2024
The particle requirements of sand in bonding mortar mainly include the following points:
Roundness requirement: River sand can produce high-quality dry-mixed mortar due to its smooth surface and mostly spherical characteristics. Although the roundness of machine-made sand is relatively poor, it can meet the requirements of dry-mixed mortar by controlling the content of flake particles not to exceed 12%.
Fineness modulus and gradation requirements: The fineness modulus of machine-made sand is generally controlled between 2.3 and 2.8 to improve the strength and fluidity of dry powder mortar, while reducing the amount of cementitious material, improving the quality of mortar and reducing production costs. The improvement of gradation is crucial to improving the performance of mortar.
Content of powder requirement: The content of stone powder generated in the production process of machine-made sand is generally controlled between 20-25%. For specific dry-mixed mortar projects, such as plastering mortar, the content of stone powder generally needs to be controlled within 10%, while the content of stone powder in masonry mortar can be appropriately higher.
Content of mud requirement: In order to ensure the performance of mortar, there are strict restrictions on the content of mud in sand. For cement mortar and cement mixed mortar with a strength grade not less than M5, the content of mud should not exceed 5%; for cement mixed mortar with a strength grade less than M5, the content of mud should not exceed 10%.
Particle size requirement of sand: Sand can generally be divided into four types: extra-fine sand, fine sand, medium sand and coarse sand. Medium sand (particle size is 0.35-0.5mm) is suitable for home decoration and is suitable for the use of bonding mortar.
To sum up, the particle requirements of sand in bonding mortar cover many aspects such as roundness, fineness modulus and gradation, content of powder and content of mud, ensuring the performance and quality of the mortar.
