Coal gangue-based cement stabilized macadam layer concrete material

Abstract

The invention discloses a coal gangue-based cement stabilized macadam layer concrete material. The cement stabilized macadam layer concrete material is prepared from the following raw materials in percentage by weight: 85-91.3% of aggregate, 3-5% of a cementing material, 0.2-1% of an additive, 0.5-2% of a waste textile fiber material and 5-7% of water, the coarse aggregate is composed of coal gangue and waste sandstone, and the particle size of the coarse aggregate is 10-30 mm; the fine aggregate is copper slag with the particle size of 1-10 mm; the mass ratio of the coal gangue to the waste sandstone is (8-15): 1. According to the cement stabilized macadam layer material prepared on the basis of solid wastes such as the coal gangue and the calcined calcium carbonate, through a reasonable proportioning and processing method, industrial wastes such as the coal gangue and the waste calcium carbonate are effectively utilized, and the toughness and the crack resistance of a cement-based material are improved by introducing a waste fiber textile material. The concrete material disclosed by the invention not only has good compression resistance and crack resistance, but also can remarkably reduce resource consumption, reduce material cost and relieve environmental burden.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete materials, and in particular relates to a gangue-based cement-stabilized crushed stone layer concrete material. Background Art

[0002] As a key bearing structure in road construction, cement stabilized base is usually used in the roadbed and base of highways, airport runways, and urban roads. Its function is to form a high-strength and stable base material through the reaction of cement and aggregate. Traditional cement stabilized base materials are mixed with cement, crushed stone (or other aggregates) and water in a certain proportion and then laid and compacted. However, with the increase in traffic load and the influence of environmental factors, traditional cement stabilized base has exposed some problems in practical applications, including cracking, insufficient durability, and high resource consumption.

[0003] Cement and natural gravel are the core materials of cement-stabilized base. A large amount of greenhouse gases such as carbon dioxide are released during the cement production process, becoming one of the important sources of global carbon emissions. According to statistics, carbon emissions from cement production account for about 7% to 8% of the world's total emissions. In addition, the widespread mining of natural gravel not only consumes a large amount of natural resources, but also leads to problems such as ecological environment damage and land degradation. With the continuous development of road infrastructure construction, resource scarcity and environmental problems are becoming more and more severe. How to reduce the use of cement and seek alternative materials for natural aggregates has become an important direction of industry research.

[0004] In actual engineering applications, traditional cement-stabilized base materials are prone to cracking under long-term loads due to their high brittleness. This cracking phenomenon not only affects the service life of the road, but also increases subsequent maintenance costs. In addition, traditional cement-stabilized base materials show insufficient durability when facing harsh climatic conditions (such as sudden temperature changes or high humidity environments), and are easily affected by rain erosion or freeze-thaw cycles, resulting in performance degradation. Therefore, improving the durability and crack resistance of cement-stabilized materials has become an urgent need.

[0005] Gangue is a byproduct of coal mining, usually in the form of solid waste. Hundreds of millions of tons of gangue are produced every year in the world. If these wastes are not properly handled, long-term accumulation will cause serious pollution to the environment. In addition, since they contain harmful substances, such as heavy metals and unburned coal powder, if they seep into groundwater or encounter rainfall erosion, they may cause water and soil pollution. Traditionally, gangue is mainly used for landfill, a small amount for power generation or building materials, but the overall utilization rate is low. How to reuse gangue as a resource, especially to reasonably replace natural resources in the field of high consumables, is an effective means to solve this environmental problem.

[0006] Calcium carbonate waste generated during the treatment of coal mine wastewater is also a headache for the environment. This type of solid waste is difficult to degrade naturally due to its high content. Long-term stacking not only occupies a large amount of land, but also poses a potential threat to the ecological environment. Calcium carbonate waste piled in an acid rain environment is prone to chemical reactions and cause pollution to spread. As a common industrial waste, although calcium carbonate contains usable calcium elements, its activity is low and it is difficult to play an effective role by direct application. Therefore, how to improve the utilization rate of calcium carbonate and stimulate its activity is a key technical challenge in realizing the resource utilization of waste.

[0007] Non-degradable polymer plastics and discarded fiber textile materials such as discarded masks are solid wastes generated in people's production and life. A large amount of them will cause serious damage to the natural environment. How to effectively deal with them is a question worth exploring.

[0008] The invention aims to provide a cement-stabilized crushed stone layer concrete material prepared by utilizing industrial wastes such as coal gangue and waste calcium carbonate. Summary of the invention

[0009] The purpose of the invention is to provide a coal gangue-based cement-stabilized crushed stone layer concrete material.

[0010] The object of the present invention is achieved by providing a gangue-based cement-stabilized crushed stone layer concrete material, which is composed of the following raw materials in weight ratio: 85-91.3% aggregate, 3-5% cementitious material, 0.2-1% additive, 0.5%-2% waste textile fiber material and 5-7% water; Among them, coarse aggregate accounts for 70-80% of the aggregate, and fine aggregate accounts for 20-30%; The coarse aggregate is composed of coal gangue and waste sandstone, with a particle size of 10-30 mm; the fine aggregate is copper slag with a particle size of 1-10 mm; the mass ratio of the coal gangue to the waste sandstone is 8-15:1; The cementitious material is a mixture of coal-based kaolin and solid waste calcium carbonate; the mass ratio of the coal-based kaolin to the solid waste calcium carbonate is 1:3-6; The additive is prepared by mixing disodium oxalate tetraacetate, PVAL, citric acid, carboxymethyl cellulose, lignin sulfonate water reducer, sodium chloride, and calcium chloride solution in a mass ratio of 1:1-5:1-3:1-7:1-4:1-8:1-5; The waste textile fiber material consists of waste masks and waste non-degradable polymer plastics in a mass ratio of 1-5:1.

[0011] The preparation method of the gangue-based cement-stabilized crushed stone layer concrete material comprises weighing various raw materials according to the formula of the gangue-based cement-stabilized crushed stone layer concrete material, and mixing them evenly to obtain the cement-stabilized crushed stone layer concrete material.

[0012] The present invention utilizes coal gangue with low kaolin content as aggregate, reduces dependence on natural resources, and solves the environmental pollution problem caused by coal gangue accumulation. At the same time, coal-based kaolin and solid waste calcium carbonate are calcined to replace cement, further improving the mechanical properties of concrete and realizing the resource utilization of waste. By using metakaolin obtained after calcining coal-based kaolin as an admixture, and introducing calcium oxide generated by calcining calcium carbonate as an alkali activator, the hydration reaction of metakaolin can be effectively promoted, and the compressive strength and durability of concrete can be significantly improved. The synergistic effect of coal gangue, sandstone, copper slag and waste fiber textile materials makes the concrete have a better mix ratio, which can effectively improve the mechanical properties of the cement-stabilized gravel layer. The use of additives can form a film on the surface of the aggregate, effectively protecting the aggregate from being expanded by water bubbles during use.

[0013] The concrete material of the present invention reduces the amount of cement used, reduces the amount of cement used in the concrete production process, and reduces carbon dioxide emissions, which has significant environmental benefits. At the same time, industrial waste is used to replace natural materials, which reduces the cost and resource consumption of concrete manufacturing.

[0014] The cement-stabilized crushed stone layer material prepared from solid wastes such as coal gangue and calcined calcium carbonate in the present invention not only effectively utilizes industrial wastes such as coal gangue and waste calcium carbonate through reasonable proportioning and processing methods, but also improves the toughness and crack resistance of cement-based materials by introducing waste fiber textile materials. The concrete material of the present invention not only has good compression and crack resistance, but also can significantly reduce resource consumption, reduce material costs, and reduce environmental burdens, and has a wide application prospect in road infrastructure and other construction fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the XRD diffraction pattern of uncalcined coal-based kaolin powder (in the figure, Zizhou refers to Zizhou County, Shaanxi Province, the source of coal gangue, and kaolin refers to kaolin, a component in coal gangue).

[0016] Figure 2 The XRD diffraction patterns of coal-based kaolin powder calcined at different calcination temperatures. DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited in any way. Any changes or improvements made based on the teachings of the present invention fall within the protection scope of the present invention.

[0018] The invention discloses a gangue-based cement-stabilized crushed stone layer concrete material, which is composed of the following raw materials in weight ratio: 85-91.3% of aggregate, 3-5% of cementitious material, 0.2-1% of additive, 0.5%-2% of waste textile fiber material and 5-7% of water; Among them, coarse aggregate accounts for 70-80% of the aggregate, and fine aggregate accounts for 20-30%; The coarse aggregate is composed of coal gangue and waste sandstone, with a particle size of 10-30 mm; the fine aggregate is copper slag with a particle size of 1-10 mm; the mass ratio of the coal gangue to the waste sandstone is 8-15:1; The cementitious material is a mixture of coal-based kaolin and solid waste calcium carbonate; the mass ratio of the coal-based kaolin to the solid waste calcium carbonate is 1:3-6; The additive is prepared by mixing disodium oxalate tetraacetate, PVAL, citric acid, carboxymethyl cellulose, lignin sulfonate water reducer, sodium chloride, and calcium chloride solution in a mass ratio of 1:1-5:1-3:1-7:1-4:1-8:1-5; The waste textile fiber material consists of waste masks and waste non-degradable polymer plastics in a mass ratio of 1-5:1.

[0019] The coal-based kaolin powder is coal-based kaolin calcined at a temperature of 600-1000° C., has a kaolin content of 30-80%, and a particle size of 30-60 μm.

[0020] The solid waste calcium carbonate is solid waste calcium carbonate calcined at a temperature of 800-1100° C., and the particle size is 20-50 μm.

[0021] The preparation method of the waste textile fiber material is as follows: the waste masks and waste non-degradable polymer plastics are disinfected and then mechanically crushed into strips with a length of 5 mm to 20 mm, and the aspect ratio is controlled at 5 to 10.

[0022] The calcium chloride concentration in the calcium chloride solution is 30-50%.

[0023] The present invention also provides a method for preparing the gangue-based cement-stabilized gravel layer concrete material, which comprises weighing various raw materials according to the formula of the gangue-based cement-stabilized gravel layer concrete material, and mixing them evenly to obtain the cement-stabilized gravel layer concrete material.

[0024] Examples 1-20 In Examples 1-20, the raw materials and component proportions in Table 1 and Table 2 were mixed and stirred for 3 to 5 minutes using a forced mixer to ensure that the materials were evenly mixed to obtain cement-stabilized crushed stone layer concrete materials.

[0025] Table 1 Mass ratio of each raw material component in Examples 1-20 Table 2 Ratios of raw materials in Examples 1-20 Experimental Example 1 Calcination Temperature Test of Coal-Based Kaolin The main components of coal-based kaolin powder are kaolin and silicon dioxide. Figure 1 and Figure 2 It can be seen that after calcining, the coal-based kaolin powder decomposes to form metakaolin. When the calcination temperature reaches 900°C, the metakaolin undergoes a secondary reaction to form mullite, which is inactive. Therefore, Examples 1-20 select coal-based kaolin powder calcined at 800°C as raw material.

[0026] Experimental Example 2 Mechanical Properties Test of Concrete Materials Prepared in Examples 1-20 The experimental method is as follows: 1) The concrete materials obtained in Examples 1-20 were respectively placed in test molds, and samples were prepared by static pressing method, with the diameter of the sample being 50 mm and the height being 100 mm; 3) The formed specimens are wet cured for 7 days at a temperature of 20°C to 25°C and a humidity of more than 90%; 4) After the curing period, the unconfined compressive strength test was carried out. The failure load of the sample was measured at a loading rate of 1 mm / min, and the unconfined compressive strength was calculated. The mechanical properties are shown in Table 3.

[0027] Table 3 Mechanical properties of concrete materials in Examples 1-20 Results: As can be seen from Table 3, the unconfined compressive strength of the cement-stabilized crushed stone layer prepared by the present invention using solid wastes such as coal gangue and calcined solid waste calcium carbonate meets the design standards for the use of ordinary highway subgrades.

Claims

1. A coal gangue-based cement-stabilized crushed stone layer concrete material, characterized in that: It is composed of the following raw materials in weight ratio: 85-91.3% aggregate, 3-5% cementitious material, 0.2-1% additive, 0.5%-2% waste textile fiber material and 5-7% water; Among them, coarse aggregate accounts for 70-80% of the aggregate, and fine aggregate accounts for 20-30%; The coarse aggregate is composed of coal gangue and waste sandstone, with a particle size of 10-30 mm; the fine aggregate is copper slag with a particle size of 1-10 mm; the mass ratio of the coal gangue to the waste sandstone is 8-15:1; The cementitious material is a mixture of coal-based kaolin and solid waste calcium carbonate; the mass ratio of the coal-based kaolin to the solid waste calcium carbonate is 1:3-6; The additive is prepared by mixing disodium oxalate tetraacetate, PVAL, citric acid, carboxymethyl cellulose, lignin sulfonate water reducer, sodium chloride, and calcium chloride solution in a mass ratio of 1:1-5:1-3:1-7:1-4:1-8:1-5; The waste textile fiber material consists of waste masks and waste non-degradable polymer plastics in a mass ratio of 1-5:

1.

2. The gangue-based cement-stabilized crushed stone layer concrete material according to claim 1, characterized in that: The coal-based kaolin powder is coal-based kaolin calcined at a temperature of 600-1000° C., has a kaolin content of 30-80%, and a particle size of 30-60 μm.

3. The gangue-based cement-stabilized crushed stone layer concrete material according to claim 1, characterized in that: The solid waste calcium carbonate is solid waste calcium carbonate calcined at a temperature of 800-1100° C., and the particle size is 20-50 μm.

4. The gangue-based cement-stabilized crushed stone layer concrete material according to claim 1, characterized in that: The preparation method of the waste textile fiber material is as follows: the waste masks and waste non-degradable polymer plastics are disinfected and then mechanically crushed into strips with a length of 5 mm to 20 mm, and the aspect ratio is controlled at 5 to 10.

5. The gangue-based cement-stabilized crushed stone layer concrete material according to claim 1, characterized in that: The calcium chloride concentration in the calcium chloride solution is 30-50%.

6. The method for preparing the gangue-based cement-stabilized crushed stone layer concrete material according to claim 1, characterized in that: According to the formula of the gangue-based cement-stabilized crushed stone layer concrete material, various raw materials are weighed and stirred evenly to obtain the cement-stabilized crushed stone layer concrete material.

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