CN115400853B - Machine-made sand modularized production process for prestressed concrete structure based on coarse aggregate shaping - Google Patents

Abstract

The invention discloses a machine-made sand modularized production process for a prestressed concrete structure based on coarse aggregate shaping, which takes coarse aggregate as a raw material, enters a coarse aggregate shaping module for shaping after surface impurity removal, and screens out coarse aggregate finished products by screening equipment; fine particles generated by shaping enter a machine-made sand production module, and the machine-made sand for the prestressed concrete structure, which is round in particle shape, reasonable in grading, and proper in stone powder content, is prepared by utilizing the technologies of mutual friction of particles, automatic screening, stone powder control and the like; the stone powder is collected by dust removing equipment in the production process, and the stone powder mineral admixture is prepared after superfine treatment. The modularized production process realizes multidimensional integrated functions such as gravel shaping, homogeneous machine-made sand preparation, stone powder ultrafining and the like, is suitable for real-time production of machine-made sand in a prestress structure factory, solves the problem that prestress concrete generates uneven stress due to different sand-stone-powder lithology, and reduces the risks of shrinkage cracking and creep arching of the prestress concrete structure.

Description

A modular production of prestressed concrete structures based on coarse aggregate shaping using machine-made sand Production process

Technical field

The invention belongs to the technical field of aggregate processing, and specifically relates to a modular production process of machine-made sand for prestressed concrete structures based on coarse aggregate shaping.

Background technique

The coarse aggregate component accounts for a large proportion of concrete, and its performance quality is closely related to the performance of concrete. Poor-quality coarse aggregate usually has sharp grain shapes, high needle-flake content, and discontinuous particle gradation, which affects the construction performance and service performance of railway engineering concrete, especially high-strength grade concrete of C50 and above for prestressed structures. Compared with the definition of needles and flake-shaped particles in Chinese standards, the requirements for needle-shaped and flake-shaped particles in European standards are more stringent. That is, particles defined as needles and flake-shaped particles in European standards may not be needle-like or flake-shaped particles in Chinese standards. , flaky particles, resulting in poor aggregate particle shape in my country. A convenient and economical way to solve the problem of poor quality coarse aggregate is to introduce aggregate shaping technology to produce coarse aggregate with a round shape, large surface friction, and continuous particle gradation, thereby improving the performance of railway engineering concrete. However, the shaping of coarse aggregate will produce a large amount of undersize material, which has sharp edges, high powder content, and poor particle gradation. It is not suitable for direct application in railway engineering cement concrete. Simply using it as roadbed filler wastes a lot of resources. There is great room for utilization of the undersize material produced after the coarse aggregate shaping process. High-quality machine-made sand for prestressed concrete structures is made by further crushing, shaping and screening the undersized materials. Compared with high-quality machine-made sand produced from parent rocks such as mine blocks, tunnel slag, pebbles and gravel, it is not only sufficient It utilizes resources and eliminates a large number of process procedures, improves the production efficiency of high-quality machine-made sand, and effectively controls the source of machine-made sand quality.

The prestressed structure of railway engineering requires concrete with high compressive strength, small shrinkage and good durability. Due to the uneven quality of machine-made sand on the current market and the lack of standardized and systematic control measures for machine-made sand production, the prestressed structure of railway engineering has The use of machine-made sand in construction may deteriorate the quality of components. Therefore, the use of machine-made sand is strictly restricted in relevant standards for prestressed structures such as railway engineering beams, sleepers, and track slabs. The stone chips produced by coarse aggregate shaping are further used to prepare high-quality machine-made sand and ultra-fine stone powder mineral admixture products for prestressed concrete structures, which can ensure that the stone, sand and powder used in prestressed structures of railway projects have unified sources and chemical The quality is the same, and the homogeneity of sand-stone-powder plays a significant role in ensuring the quality of machine-made sand prestressed concrete components.

Chinese patent CN201910485981.6 discloses a high-quality machine-made sand production process. It uses 2-20mm limestone as raw material. After processing in a mill, it is recycled and sorted multiple times to produce high-quality machine-made sand. However, the processing raw materials in this patent require The limestone is 2-20mm, which greatly limits the source of masterbatch, and the processing procedures are complex, which is not conducive to the improvement of production efficiency. Chinese patent CN201811026945.5 discloses a high-quality machine-made sand production process. It mainly installs a grain shape optimization machine after the vibrating screen, and uses the screening device set up in the grain shape optimization machine to finely control the machine-made sand grading to produce high-quality machine-made sand. Sand, this patent does not indicate the mesh size of fine screening, and it is difficult to implement fine screening technology in the production process. Chinese patent CN201810324643. agglomeration, improved material fluidity, and improved screening efficiency, thereby improving material crushing and machine-made sand shaping efficiency. However, the addition of shaping agents in this patent is not conducive to low production cost control of machine-made sand. Chinese patent CN201320476163.8 discloses a gravel shaping system with an online dust removal device. This patent uses a negative pressure bag dust collector to recycle the stone powder in the gravel shaping system. However, this patent only solves the problem of stone powder recycling. . At present, there is still a lack of a production process that can conveniently and efficiently produce high-quality machine-made sand for prestressed structures in railway projects.

Contents of the invention

In order to solve the problems of difficult quality control of machine-made sand for prestressed structures in railway engineering and waste of stone chip by-product resources after coarse aggregate shaping, this invention invented a modular production process of machine-made sand for prestressed structures based on coarse aggregate shaping. This process can make full use of gravel resources to produce fine-grained coarse aggregate, high-quality machine-made sand for prestressed concrete structures, and ultra-fine fossil powder mineral admixtures, ensuring the stone, sand, and powder used in prestressed structures of railway projects. Uniform and homogeneous, thus improving the quality of prestressed structures in railway projects.

In order to achieve the above object, the present invention adopts the following technical solutions:

A modular production process of machine-made sand for prestressed concrete structures based on coarse aggregate shaping. The process is characterized by: the process uses coarse aggregate as raw material. After surface impurities are removed, it enters the coarse aggregate shaping module for shaping, and is screened. The sub-equipment screens out the finished coarse aggregate after shaping; the undersize material produced by shaping enters the machine-made sand production module to produce machine-made sand for prestressed concrete structures with rounded grain shape, reasonable gradation and appropriate stone powder content; the production process The stone powder produced in the process is collected by dust removal equipment, and the stone powder mineral admixture is obtained after ultrafine treatment;

The maximum particle size of the coarse aggregate raw materials is 31.5mm-40mm. The raw materials are cleaned and impurities are removed and then stored. The sewage treatment after cleaning adopts a water circulation system. The moisture content of the raw materials during production is not more than 3%;

The production modules are divided into coarse aggregate shaping modules, machine-made sand preparation modules, and stone powder ultra-fine refinement modules. The three production modules are uniformly arranged inside the prestressed concrete structure production factory, and the raw materials are stored adjacent to the prestressed concrete structure factory. district;

The coarse aggregate shaping module of the production module is composed of a crusher, a screening machine and a belt conveyor. The crusher is one or more combinations of a cone crusher, an impact crusher and a vertical shaft impact crusher. The screening machine is one or more combinations of linear vibrating screen, circular vibrating screen and high-frequency vibrating screen. The installation inclination angle of the screening machine is 38°-45°. The shape of the screen holes is round holes or square holes. The screen The hole size is 5-30mm; the finished coarse aggregate after shaping is of three single-grain sizes: 5-10mm, 10-16mm, and 16-25mm, with a mass ratio of (20%-40%): (35%-45 %): (20%-40%), the total content of needles and flake particles of each particle size is not more than 3%, the circularity is not less than 0.85, the aspect ratio is not more than 1.55, and the mud content is not more than 0.5%, the mud content is 0;

The machine-made sand preparation module of the production module consists of a sand making machine, a screening machine and a bucket elevator. The sand making machine consists of one or more vertical shaft impact crushers. The screening machine is a linear vibrating screen or a circular vibrating screen. One or more combinations of sieves and high-frequency vibrating screens, the installation inclination angle of the screening machine is 38°-45°, the shape of the sieve holes is round holes or square holes, and the sieve hole size is 3-5mm; prestressed concrete structure The finished products of machine-made sand are divided into two types: 0-3mm and 3-5mm, with a mass ratio of (75%-90%): (10%-25%). The total mass of finished machine-made sand is lower than the total mass of finished sand and gravel. (35%-40%), additional 5-10mm gravel is used as raw material to produce machine-made sand. The roundness of the finished machine-made sand of 3-5mm particle size is not less than 0.85, the aspect ratio is not greater than 1.60, and the 0-3mm particle size The stone powder content of finished machine-made sand shall not exceed 5%. When preparing prestressed structural concrete, the finished sand and gravel shall be proportionally designed to be 0-25mm fully graded aggregate, with a tight void ratio of less than 40% and a particle fineness of 0.015mm-4.75mm. Modulus is 2.6-3.2;

The stone powder ultra-fine refinement module of the production module is composed of a stone powder recovery sub-module and a stone powder grinding sub-module. The stone powder recovery sub-module is composed of a fan, a dust collector, a dust removal duct and an exhaust hood. The dust removal duct is used for coarse aggregate shaping. It is installed in both the module and the machine-made sand production module. The total dust removal efficiency of the dust collector is not less than 95%. The fine stone grinding sub-module consists of one or more grinding machines; the ultra-fine stone powder mineral admixture is The specific surface area is not less than 500m ² /kg, and the moisture content is not more than 1%.

According to the modular production process of machine-made sand for prestressed concrete structures based on coarse aggregate shaping, it is characterized in that the total finished product yield is not less than 90%, the finished products of various particle sizes are stored in separate warehouses, and the height of the material pile does not exceed 5m. Stone powder mineral admixtures are stored in metal tanks.

The beneficial effects of the present invention are:

(1) Production process integration: coarse aggregate shaping, machine-made sand preparation, ultra-fine stone powder and railway engineering prestressed concrete structure production are jointly arranged, and fine-grained coarse aggregate, high-quality machine-made sand and ultra-fine fossil powder minerals are mixed After the production of the composite materials, long-distance transportation can be avoided and used directly as raw materials for the production of prestressed concrete structures for railway projects, which prevents problems such as contamination of raw materials and large quality fluctuations during the transportation process. Moreover, after the production process is integrated, only sufficient preparation is required The crushed stone raw materials can ensure the timely supply of raw materials and prevent delays in production and construction schedules.

(2) Modularization of the production system: Coarse aggregate shaping, machine-made sand production, and stone powder ultra-fine refinement are separate production modules and are interrelated. The modular layout is conducive to reducing land occupation and making full use of the site, and the modular layout is conducive to equipment maintenance. and maintenance.

(3) Homogenization of raw materials: The coarse aggregate, machine-made sand and stone powder admixtures produced by this process are all derived from the same base material, and the product quality meets the technical requirements for railway concrete for coarse and fine aggregates and stone powder admixtures. , which solves the problem of non-uniform stress in precast concrete due to different lithologies of sand, stone and silt, and reduces the risk of concrete shrinkage cracking, creep and arching.

(4) Refined concrete mix proportion design: The coarse aggregate, machine-made sand and stone silty admixtures produced by this process have various particle sizes, and can be prepared into a skeleton with continuous gradation, tight porosity and low porosity through proportional design, thereby preparing Prestressed concrete with high strength, good compactness and small deformation.

Description of drawings

In order to explain the embodiments of the present invention more clearly, the following will briefly introduce the drawings needed to describe the embodiments. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, It is said that other drawings can be obtained based on these drawings without exerting any creative effort.

Figure 1 is an example diagram of the layout of the present invention in a prestressed concrete structure production plant.

Detailed ways

The technical solution of the present invention will be further described in detail below through examples and in conjunction with the accompanying drawings.

Referring to Figure 1, a modular production process of machine-made sand for railway engineering prestressed concrete structures based on coarse aggregate shaping according to the present invention is shown. The main implementation steps are:

(1) Coarse aggregate with a maximum particle size of 40mm is used as the production raw material. Cleaning equipment is used to remove impurities on the surface of the raw material. The flushing water flows into the sewage treatment system through the iron grid on the ground. The sewage treatment system uses circulating water.

(2) After cleaning, the raw materials are allowed to stand for 2-3 hours, and the moisture content is controlled to be less than 3%. The raw materials are sent to the coarse aggregate shaping module. The coarse aggregate is first crushed and shaped in the impact crusher, and the particle size becomes smaller. Then it enters the vertical shaft impact crusher for crushing and shaping to form coarse aggregate finished products with round particles and large surface friction.

(3) After the shaped coarse aggregate is screened by the circular vibrating screen combination screen surface, the gravel larger than 25mm continues to return to the coarse aggregate shaping module, and the gravel not larger than 25mm is screened by the screening equipment into 5-10mm, 10 -Three-grade coarse aggregate finished products of 16mm and 16-25mm and 0-5mm sieve scraps. The coarse aggregate finished products are transported to the finished product warehouse by a belt for storage, while the sieve scraps continue to the next step of processing.

(4) Regulate the relevant parameters of the coarse aggregate shaping system and screening equipment, and set the mass ratio of the three types of single-grain coarse aggregate finished products of 5-10mm, 10-16mm, and 16-25mm to 25%: 30%: 45 %.

(5) The undersized material enters the machine-made sand production module, which consists of two vertical shaft impact crushers. After the undersized material is shaped by the vertical shaft impact crusher, it is screened by the screening equipment into 0-3mm, 3- The finished product of 5mm machine-made sand has a mass ratio of 85%:15%. The finished product is transported to the finished product warehouse by a belt for storage. The undersize material larger than 5mm continues to return to the sand making system for sand making and shaping.

(6) When the proportion of finished manufactured sand is low, add 5-10mm gravel to increase the proportion of finished manufactured sand. When the proportion of finished manufactured sand is high, reduce the coarse aggregate shaping time to reduce the amount of sand entering the machine-made sand production module. In terms of material quantity, the proportion of finished manufactured sand is controlled to about 38% of the total mass of sand and gravel.

(7) The dust removal air duct is installed in both the coarse aggregate shaping module and the machine-made sand production module. The stone powder produced during the processing is collected in the dust collector and further processed by the stone powder ultra-fineness module to obtain ultra-fine fossil powder. The stone powder ultra-fine refinement module consists of a stone powder recovery sub-module and a stone powder grinding sub-module. The stone powder recovery sub-module consists of a fan, a dust collector, a dust removal duct and an exhaust hood. The total dust removal efficiency of the dust collector is 99%, and the stone powder grinding sub-module is The sub-module is a grinding machine, and the collected stone powder is ground into ultra-fine powder to obtain a stone powder mineral admixture.

(8) The total production efficiency of this process is 95%. The needle and flake content of the finished coarse aggregate is 1%, the roundness is 0.87, the aspect ratio is 1.43, the mud content is 0.2%, and the mud lumps The content is 0; the circularity of the finished product of 3-5mm particle size machine-made sand is 0.86, the aspect ratio is not greater than 1.46, and the stone powder content of the finished product of 0-3mm particle size machine-made sand is 3%; the stone powder after ultra-fine treatment is less than 1.46. The surface area is 550m ² /kg, and the moisture content is 0.4%.

(9) During the production of prestressed concrete structures, fine-grained coarse aggregate, high-quality machine-made sand and ultra-fine stone powder are prepared directly from the coarse aggregate storage area, fine aggregate storage area and ultra-fine stone powder storage area according to the concrete mix ratio. To form the prestressed structure of the railway project, the sand and gravel aggregates are designed to be 0-25mm fully graded aggregates, with a tight void rate of 36%, a fineness modulus of 0.015mm-4.75mm particles of 2.7, and a cementing amount of stone powder. 10% of the total amount of materials.

The above description of the embodiments is to facilitate those of ordinary skill in the technical field to understand and apply the present invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without inventive efforts. Therefore, the present invention is not limited to the embodiments here. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention should be within the protection scope of the present invention.

Claims (2)

1. A machine-made sand modularized production process for a prestressed concrete structure based on coarse aggregate shaping is characterized by comprising the following steps of: the process takes coarse aggregate as a raw material, enters a coarse aggregate shaping module for shaping after surface impurity removal, and screens out shaped coarse aggregate finished products by screening equipment; the undersize produced by shaping enters a machine-made sand production module to prepare the machine-made sand for the prestressed concrete structure, which has round grain shape, reasonable grading and proper stone powder content; the stone powder produced in the production process is collected by dust removal equipment, and the stone powder mineral admixture is prepared after superfine treatment;

the maximum grain diameter of the coarse aggregate raw material is 31.5mm-40mm, the raw material is cleaned, subjected to impurity removal, placed still and stored, and the sewage treatment after cleaning adopts a water circulation system, so that the water content of the raw material is not more than 3% during production;

the production modules are divided into a coarse aggregate shaping module, a machine-made sand preparation module and a stone powder superfine module, and the three production modules are uniformly arranged in a prestressed concrete structure production factory and are close to a raw material storage area in the prestressed concrete structure factory;

the coarse aggregate shaping module of the production module consists of a crusher, a screening machine and a belt conveyor, wherein the crusher is one or more of a cone crusher, an impact crusher and a vertical shaft type impact crusher, the screening machine is one or more of a linear vibrating screen, a circular vibrating screen and a high-frequency vibrating screen, the installation inclination angle of the screening machine is 38-45 degrees, the shape of a screen hole is a round hole or a square hole, and the size of the screen hole is 5-30mm; the shaped coarse aggregate finished product is in three single particle grades of 5-10mm, 10-16mm and 16-25mm, and the mass ratio of the coarse aggregate finished product is (20% -40%): (35% -45%): (20% -40%), the total content of needle and flaky particles of each size fraction is not more than 3%, the circularity is not less than 0.85, the length-diameter ratio is not more than 1.55, the mud content is not more than 0.5%, and the mud block content is 0;

the machine-made sand preparation module of the production module consists of a sand making machine, a screening machine and a bucket elevator, wherein the sand making machine consists of one or more than one vertical shaft type impact crusher, the screening machine is one or more than one composition of a linear vibrating screen, a circular vibrating screen and a high-frequency vibrating screen, the installation inclination angle of the screening machine is 38-45 degrees, the shape of a screen hole is a round hole or a square hole, and the size of the screen hole is 3-5mm; the finished product of the machine-made sand for the prestressed concrete structure is 0-3mm and 3-5mm, and the mass ratio of the machine-made sand to the finished product is (75% -90%): when the total mass of the finished product of the machine-made sand is lower than that of the finished product of the sand stone (35% -40%), 5-10mm broken stone is additionally used as a raw material to produce the machine-made sand, the circularity of the finished product of the machine-made sand with the grain size of 3-5mm is not less than 0.85, the stone powder content of the finished product of the machine-made sand with the grain size of no more than 1.60,0-3mm is not more than 5%, the finished product of the sand stone is proportionally designed into 0-25mm full-graded aggregate with the tight void ratio of less than 40%, and the fineness modulus of 0.015-4.75 mm particles is 2.6-3.2;

the stone powder ultra-fine module of the production module consists of a stone powder recovery submodule and a stone powder grinding submodule, wherein the stone powder recovery submodule consists of a fan, a dust remover, a dust removing air pipe and an exhaust hood, the dust removing air pipe is arranged in the coarse aggregate shaping module and the machine-made sand production module, the total dust removing efficiency of the dust remover is not less than 95%, and the stone powder grinding submodule consists of one or more grinding machines; the specific surface area of the stone powder mineral admixture after ultra-refinement is not less than 500m ² The water content is not more than 1 percent per kg.

2. The machine-made sand modularized production process for the prestressed concrete structure based on coarse aggregate shaping, which is characterized in that the total yield is not less than 90%, finished products with various grain sizes are stored in different bins, the height of a material pile is not more than 5m, and stone powder mineral admixture is stored by adopting a metal tank body.