With the continuous development of science and technology, as well as the gradual depletion and decreasing quality of natural sand, it has become difficult to meet the current construction demand for sand. Mechanism sand, known for its excellent durability and mechanical performance, is widely used in the construction of bridges and highways. The quality of mechanism sand directly affects the engineering quality and safety. So, what are the standards for using mechanism sand in road and bridge construction?
First, the particle size of mechanism sand should meet relevant standards to ensure its uniformity and compactness when mixed with materials like concrete. Second, the impurity content in mechanism sand should be controlled within a certain range to avoid adverse effects on engineering quality. Finally, mechanism sand should have sufficient strength and durability to withstand various stresses during construction. This requires sand-making machines to ensure the integrity and stability of sand particles during the production process.
In road and bridge construction, stone materials are divided into coarse aggregate and fine aggregate based on their particle size. In asphalt mixtures, the boundary is typically 2.36mm, while in cement concrete, it is 5mm.
Technical requirements for stone materials are as follows:
Grade I - Strong rock
Grade II - Strong rock
Grade III - Moderately strong rock
Grade IV - Soft rock
Based on the particle size of the sand, it can be classified as:
(1) Very coarse aggregate, D ≥ 37.5mm
(2) Coarse aggregate, D = 31.5/26.5, used for base and subbase layers
(3) Medium aggregate, D = 19/16mm
(4) Fine aggregate, D = 13.2/9.5mm, used for surface layers
(5) Sand, D ≤ 4.75mm, used for wearing course
For general fine aggregate concrete, fine aggregate with a particle size smaller than 4.75mm, well-graded, hard in texture, and clean in particles, such as artificial mechanism sand, is commonly used. Additionally, crushed stone materials produced by crushers can also be used for cement-soil, cement-sand, and other applications.
To produce mechanism sand that meets the standards of road and bridge construction, it is crucial to choose a good sand-making machine. Below, we recommend one type of sand-making machine:
PLS Vertical Impact Sand Making Machine
The PLS vertical impact crusher utilizes two different crushing mechanisms, "rock-on-rock" and "rock-on-iron," depending on the working conditions or the nature of the crushed materials. "Rock-on-rock" uses a waterfall dividing system to split the incoming materials into two streams in a controlled manner. One stream enters the high-speed rotating impeller chamber horizontally through the center feed pipe, while the other stream falls into the equipment chamber through multiple overflow outlets on the periphery of the feed hopper. The material entering the impeller chamber is accelerated by the high-speed rotation of the impeller and ejected from three or more discharge ports, colliding with the material falling from the overflow outlets in the circumferential area of the impeller, resulting in intense self-collision and crushing. "Rock-on-iron" directs all incoming materials from the center feed pipe into the high-speed rotating impeller chamber, where they are accelerated by the high-speed rotation of the impeller and ejected from three or more discharge ports, violently colliding with the metal impact plates installed on the inner wall of the equipment chamber, resulting in rock-on-iron crushing.
It is widely used in various industries such as metal and non-metal mines, refractory materials, abrasive ceramics, building materials, high-speed railways, water conservancy and hydropower construction, and the production of sand and aggregates in civilian sectors.