The machine sand production line is made by crushing, screening and dusting the reusable materials such as limestone, tailings and construction waste by a new sand making machine, as a fine aggregate of dry mixed mortar. Compared with river sand, the quality of the mechanical sand has a greater impact on the performance of the dry mortar and must be strictly controlled. Therefore, the particle grading, fineness, stone powder content and mud content index of the mechanism sand were analyzed and limited.
(1) Particle grading and fineness: The mechanism sand particles have many sharp corners and rough surface, and more reasonable grading is needed to be suitable for use in a fluid storage tank. According to the general dry mortar and special mortar mix design rules for the preparation of high strength ordinary mortar and special mortar for the use of fine aggregate.
(2) Stone powder content: In the production process, the mechanical sand inevitably produces a certain amount of stone powder. When the content of stone powder in sand is less than 5%, the dry mortar has poor workability, mainly characterized by poor bleeding, poor cohesiveness and poor fluidity; when the content of stone powder in sand is above 15%, the consistency of dry-mixed mortar is It can meet the construction requirements, but the dry-mixed mortar is thicker and has a problem of large resistance during the mixing and pumping process. When the content of the stone powder in the sand is between 8% and 12%, the dry-mixed mortar has good workability. The corresponding initial slump and the slump value after 1h are ideal and can meet the construction needs. It can be seen that the stone powder content has a great influence on the performance of the dry mixed mortar, and the stone powder content should be required in the production of the mechanism sand. Based on this, the stone powder in the mechanism sand is controlled at 9%.
(3) Mud content: Although the stone powder particles in the mechanism sand are less than 75um, unlike the mud contained in the so-called sand, the mud contained in the sand is harmful to the dry mortar, which seriously affects the aggregate and pulp. The cohesive force between the bodies causes the dry-mixed mortar to shrink during construction and the compactness to decrease, and the content must be strictly controlled. According to the provisions of the building sand standard, the methylene blue adsorption value is used to determine the amount of mud in the mechanism sand. Since the methylene blue MB value directly affects the construction performance of the dry mortar, it is required to be strict in the mechanism sand production. Control the soil to bring in, and determine that the methylene blue MB value should not exceed 0.5g/kg.
(4) When the content of stone powder in the mechanism sand is 9%, 15%-20% fly ash and 20%~25% slag powder compound can replace the cement, and the mixture can be prepared to have good performance and the strength grade is C60. Pumping high performance dry mix mortar.
(5) Control mechanism sand quality index, select suitable raw materials and mix appropriate admixtures, and machine sand can replace C60 high-performance dry-mix mortar separately.
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