High-performance coal gangue pavement concrete and preparation method thereof

Abstract

The invention relates to the technical field of concrete, and provides high-performance coal gangue pavement concrete and a preparation method thereof.The high-performance coal gangue pavement concrete is prepared from, by weight, 145-150 parts of coal gangue, 135-145 parts of sand, 25-30 parts of water, 45-55 parts of cement, 10-15 parts of fly ash, 25-30 parts of modifier and 0.3-0.5 part of water reducing agent; the coal gangue is pretreated coal gangue, and the pretreated coal gangue is obtained by treating coal gangue with acrylic acid modified polyester resin and polyester modified acrylic resin; the hydroxyl group of the acrylic modified polyester resin is 7mgKOH / g; the hydroxyl value of the polyester modified acrylic resin is 4 mgKOH / g; the raw materials of the modifier comprise nano silicon dioxide and steel fibers. Through the technical scheme, the problem of low mechanical strength of the coal gangue pavement concrete in related technologies is solved.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, specifically to a high-performance coal gangue pavement concrete and its preparation method. Background Technology

[0002] As the core load-bearing layer of transportation infrastructure, the road surface needs to withstand complex and high-intensity loads continuously. The mechanical strength of the road surface concrete directly determines the structural integrity and long-term service capacity of the road, and is related to the economic efficiency and traffic safety of road surface engineering.

[0003] In the field of road construction, traditional road concrete mainly relies on natural aggregates such as river sand and gravel. However, with the continuous advancement of infrastructure construction, the demand for natural aggregates has increased dramatically, and prices have continued to rise, leading to increased concrete costs. Coal gangue is a solid waste discharged during coal mining and washing. Therefore, a large amount of coal gangue is generated along with coal production. Long-term stockpiling of coal gangue not only occupies land but may also pollute the environment. Therefore, applying it to road concrete can both realize the resource utilization of coal gangue and reduce road construction costs.

[0004] However, the physical and chemical properties of coal gangue in coal gangue pavement concrete differ from those of natural sand and gravel, resulting in poor mechanical strength of the pavement concrete. This limits the improvement of the mechanical strength of coal gangue pavement concrete and, to some extent, affects its widespread application. Summary of the Invention

[0005] This invention proposes a high-performance coal gangue pavement concrete and its preparation method, which solves the problem of low mechanical strength of coal gangue concrete in related technologies.

[0006] The technical solution of the present invention is as follows: This invention proposes a high-performance coal gangue pavement concrete, comprising the following raw materials in parts by weight: 145-150 parts coal gangue, 135-145 parts sand, 25-30 parts water, 45-55 parts cement, 10-15 parts fly ash, 25-30 parts modifier, and 0.3-0.5 parts water-reducing agent. The coal gangue is pretreated coal gangue, which is obtained by treating coal gangue with acrylic acid-modified polyester resin and polyester-modified acrylic resin; the hydroxyl value of the acrylic acid-modified polyester resin is 7 mg KOH / g; the hydroxyl value of the polyester-modified acrylic resin is 4 mg KOH / g. The raw materials for the modifier include nano-silica and steel fibers.

[0007] As a further technical solution, the mass ratio of the acrylic-modified polyester resin to the polyester-modified acrylic resin is 5:2~3, preferably 2:1.

[0008] In this invention, the mass ratio of acrylic-modified polyester resin and polyester-modified acrylic resin for pretreatment of coal gangue is further defined as 5:2~3. When the mass ratio of acrylic-modified polyester resin and polyester-modified acrylic resin is within the defined range, the effect on improving the compressive strength of coal gangue pavement concrete is significant. When the mass ratio of the two is outside the defined range, the effect on improving the compressive strength of coal gangue pavement concrete will be reduced.

[0009] As a further technical solution, the mass of the acrylic-modified polyester resin and the polyester-modified acrylic resin is 3% to 6% of the mass of coal gangue, preferably 5%.

[0010] As a further technical solution, the method for preparing the pretreated coal gangue includes the following steps: S1. After calcining coal gangue, calcined coal gangue is obtained. S2. Acrylic acid-modified polyester resin and calcined coal gangue are added to ethyl acetate and mixed to obtain a mixture; S3. Add polyester-modified acrylic resin to the mixture, mix, and then dry to obtain pretreated coal gangue.

[0011] As a further technical solution, the calcination temperature is 600~700℃, and the calcination time is 0.5~1h.

[0012] As a further technical solution, in step S2, the mixing temperature is 40~50℃ and the mixing time is 1~2h.

[0013] As a further technical solution, in step S3, the mixing temperature is 40~50℃ and the mixing time is 0.5~1h.

[0014] As a further technical solution, the raw materials of the modifier also include trimethylchlorosilane and biphenyl-4-carboxylic acid methyl ester.

[0015] The modifiers in this invention include nano-silica, steel fibers, trimethylchlorosilane, and methyl biphenyl-4-carboxylate. The addition of nano-silica and steel fibers can synergistically improve the compressive strength of coal gangue pavement concrete. However, nano-silica may agglomerate during the mixing process of coal gangue pavement concrete. The addition of trimethylchlorosilane and methyl biphenyl-4-carboxylate can effectively solve the agglomeration phenomenon of nano-silica during the mixing process, thereby better exerting the modification effect of nano-silica on coal gangue pavement concrete and further improving the compressive strength of coal gangue pavement concrete.

[0016] As a further technical solution, the mass ratio of the nano-silica, steel fiber, trimethylchlorosilane and biphenyl-4-carboxylic acid methyl ester is 20:10:0.5:0.1~0.2.

[0017] As a further technical solution, nano-silica, trimethylchlorosilane and biphenyl-4-carboxylic acid methyl ester are added to a solution, mixed, and dried to obtain pretreated nano-silica. The pretreated nano-silica is then mixed with steel fibers to obtain a modifier.

[0018] As a further technical solution, the solution is anhydrous ethanol.

[0019] As a further technical solution, the water-reducing agent is a polycarboxylate water-reducing agent.

[0020] The addition of coal gangue in this invention leads to the absorption of more water, resulting in high water demand and poor fluidity in coal gangue concrete during mixing. Specifically, this manifests as easy clumping and difficulty in pumping after mixing, and can also cause construction defects and a reduction in the mechanical strength of the coal gangue concrete. The addition of polycarboxylate superplasticizer solves the problem of high water demand from coal gangue and reduces the water-cement ratio, thereby ensuring that the coal gangue concrete possesses high mechanical strength and comprehensive performance.

[0021] As a further technical solution, the cement is PO 42.5 silicate cement.

[0022] The present invention also proposes a method for preparing high-performance coal gangue pavement concrete, which includes the following steps: mixing the raw materials evenly to obtain high-performance coal gangue pavement concrete.

[0023] The working principle and beneficial effects of this invention are as follows: In this invention, coal gangue in coal gangue pavement concrete is pretreated with acrylic acid-modified polyester resin and polyester-modified acrylic resin. The resulting pretreated coal gangue improves the compressive strength of the coal gangue pavement concrete. Existing coal gangue pavement concrete suffers from low compressive strength. This invention addresses this issue by using acrylic acid-modified polyester resin and polyester-modified acrylic resin to pretreat the coal gangue. When this pretreated coal gangue is added to the pavement concrete, compared to untreated coal gangue, it mitigates the decrease in mechanical strength caused by the difference in physicochemical properties between coal gangue and natural sand and gravel, thereby improving the compressive strength of the coal gangue pavement concrete and expanding its application range. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] In the following embodiments and comparative examples: Polyester-modified acrylic resin, model SGR-2600, with hydroxyl content of 4 mgKOH / g and acid value of 1 mgKOH / g; and acrylic-modified polyester resin, model SGR-2400, with hydroxyl content of 7 mgKOH / g and acid value of 1 mgKOH / g; both were purchased from Guangzhou Changhao Trading Co., Ltd. Cement: PO 42.5 grade silicate cement; Fly ash: Grade I fly ash; Coal gangue, particle size 325 mesh; Sand composed of sand and gravel with a particle size of 2~3mm and 8~10mm in a mass ratio of 1.5:1; Nano silica: average particle size 20nm; Steel fiber: end hook type, length 25mm, diameter 0.5mm, manufactured by Anping County Zhihui Engineering Materials Co., Ltd.; Polycarboxylate superplasticizer, model PC-1021, manufactured by Zhengzhou Chengrui Chemical Products Co., Ltd.

[0026] Example 1 A high-performance coal gangue pavement concrete comprises the following raw materials in parts by weight: 145 parts coal gangue, 135 parts sand, 25 parts water, 45 parts cement, 10 parts fly ash, 25 parts modifier, and 0.3 parts water-reducing agent; wherein the modifier is composed of nano-silica and steel fiber in a mass ratio of 2:1. A method for preparing high-performance coal gangue pavement concrete includes the following steps: mixing the above raw materials evenly to obtain high-performance coal gangue pavement concrete; The coal gangue is pretreated coal gangue, and the preparation method of pretreated coal gangue includes the following steps: S1. After calcining coal gangue at 700℃ for 0.5h, calcined coal gangue is obtained. S2. Calcined coal gangue and acrylic acid-modified polyester resin were added to ethyl acetate and mixed at 40°C for 2 hours to obtain a mixture. S3. Add polyester-modified acrylic resin to the mixture, mix at 40°C for 1 hour, and then dry to obtain pretreated coal gangue. The total mass of polyester-modified acrylic resin and acrylic-modified polyester resin is 5% of the mass of coal gangue. The mass ratio of acrylic-modified polyester resin to polyester-modified acrylic resin is 5:2. The mass-volume ratio of coal gangue to ethyl acetate is 1g:9mL.

[0027] Example 2 A high-performance coal gangue pavement concrete comprises the following raw materials in parts by weight: 147 parts coal gangue, 140 parts sand, 28 parts water, 50 parts cement, 12 parts fly ash, 28 parts modifier, and 0.4 parts water-reducing agent; wherein the modifier is composed of nano-silica and steel fiber in a mass ratio of 2:1. A method for preparing high-performance coal gangue pavement concrete includes the following steps: mixing the above raw materials evenly to obtain high-performance coal gangue pavement concrete; The coal gangue is pretreated coal gangue, and the preparation method of pretreated coal gangue includes the following steps: S1. After calcining coal gangue at 700℃ for 0.5h, calcined coal gangue is obtained. S2. Calcined coal gangue and acrylic acid-modified polyester resin were added to ethyl acetate and mixed at 40°C for 2 hours to obtain a mixture. S3. Add polyester-modified acrylic resin to the mixture, mix at 50°C for 1 hour, and then dry to obtain pretreated coal gangue. The total mass of acrylic acid-modified polyester resin and polyester-modified acrylic resin is 5% of the mass of coal gangue. The mass ratio of acrylic acid-modified polyester resin to polyester-modified acrylic resin is 5:2. The mass-volume ratio of coal gangue to ethyl acetate is 1g:9mL.

[0028] Example 3 A high-performance coal gangue pavement concrete comprises the following raw materials in parts by weight: 150 parts coal gangue, 145 parts sand, 30 parts water, 55 parts cement, 15 parts fly ash, 30 parts modifier, and 0.5 parts water-reducing agent; wherein the modifier is composed of nano-silica and steel fiber in a mass ratio of 2:1. A method for preparing high-performance coal gangue pavement concrete includes the following steps: mixing the above raw materials evenly to obtain high-performance coal gangue pavement concrete; The coal gangue is pretreated coal gangue, and the preparation method of pretreated coal gangue includes the following steps: S1. After calcining coal gangue at 700℃ for 0.5h, calcined coal gangue is obtained. S2. Calcined coal gangue and acrylic acid-modified polyester resin were added to ethyl acetate and mixed at 40°C for 2 hours to obtain a mixture. S3. Add polyester-modified acrylic resin to the mixture, mix at 40°C for 1 hour, and then dry to obtain pretreated coal gangue. The total mass of acrylic acid-modified polyester resin and polyester-modified acrylic resin is 5% of the mass of coal gangue. The mass ratio of acrylic acid-modified polyester resin to polyester-modified acrylic resin is 5:2. The mass-volume ratio of coal gangue to ethyl acetate is 1g:9mL.

[0029] Example 4 Compared with Example 1, the only difference in Example 4 is the preparation method of the pretreated coal gangue. The preparation method of the pretreated coal gangue in this example includes the following steps: S1. After calcining coal gangue at 700℃ for 0.5h, calcined coal gangue is obtained. S2. Calcined coal gangue and polyester-modified acrylic resin were added to ethyl acetate and mixed at 40°C for 2 hours to obtain a mixture. S3. Add acrylic-modified polyester resin to the mixture, mix at 40°C for 1 hour, and then dry to obtain pretreated coal gangue. The total mass of acrylic acid-modified polyester resin and polyester-modified acrylic resin is 5% of the mass of coal gangue. The mass ratio of acrylic acid-modified polyester resin to polyester-modified acrylic resin is 5:2. The mass-volume ratio of coal gangue to ethyl acetate is 1g:9mL.

[0030] Example 5 Compared with Example 1, the only difference in this example is the preparation method of the pretreated coal gangue. The preparation method of the pretreated coal gangue in this example includes the following steps: S1. After calcining coal gangue at 700℃ for 0.5h, calcined coal gangue is obtained. S2. Calcined coal gangue, polyester-modified acrylic resin and acrylic resin-modified polyester resin are added to ethyl acetate and mixed at 40°C for 3 hours. After drying, pretreated coal gangue is obtained. The total mass of acrylic acid-modified polyester resin and polyester-modified acrylic resin is 5% of the mass of coal gangue. The mass ratio of acrylic acid-modified polyester resin to polyester-modified acrylic resin is 5:2. The mass-volume ratio of coal gangue to ethyl acetate is 1g:9mL.

[0031] Example 6 Compared with Example 1, the only difference in this example is that the mass ratio of acrylic modified polyester resin to polyester modified acrylic resin is 5:2.5.

[0032] Example 7 Compared with Example 1, the only difference in this example is that the mass ratio of acrylic modified polyester resin to polyester modified acrylic resin is 5:3.

[0033] Example 8 Compared with Example 1, the only difference in this example is the modifier. The preparation method of the modifier in this example includes the following steps: nano-silica is added to anhydrous ethanol and dispersed evenly, then trimethylchlorosilane is added and mixed at 40°C for 1 hour, and then dried to obtain pretreated nano-silica. The pretreated nano-silica and steel fibers are mixed to obtain the modifier. The mass ratio of nano-silica, steel fibers and trimethylchlorosilane is 20:10:0.6; the mass-volume ratio of nano-silica and anhydrous ethanol is 1g:6mL.

[0034] Example 9 Compared with Example 1, the only difference in this example is the modifier. The preparation method of the modifier in this example includes the following steps: nano-silica is added to anhydrous ethanol and dispersed evenly, then biphenyl-4-carboxylic acid methyl ester is added and mixed at 40°C for 1 hour, and then dried to obtain pretreated nano-silica. The pretreated nano-silica and steel fiber are mixed to obtain the modifier. The mass ratio of nano-silica, steel fiber and biphenyl-4-carboxylic acid methyl ester is 20:10:0.6; the mass-volume ratio of nano-silica and anhydrous ethanol is 1g:6mL.

[0035] Example 10 Compared with Example 1, the only difference in this example is the modifier. The preparation method of the modifier in this example includes the following steps: nano-silica is added to anhydrous ethanol and dispersed evenly, then trimethylchlorosilane and biphenyl-4-carboxylic acid methyl ester are added and mixed at 40°C for 1 hour, and then dried to obtain pretreated nano-silica. The pretreated nano-silica is then mixed with steel fibers to obtain the modifier. The mass ratio of nano-silica, steel fibers, trimethylchlorosilane and biphenyl-4-carboxylic acid methyl ester is 20:10:0.5:0.1; the mass-volume ratio of nano-silica to anhydrous ethanol is 1g:6mL.

[0036] Comparative Example 1 Compared with Example 4, the only difference in this comparative example is the preparation method of the pretreated coal gangue. The preparation method of the pretreated coal gangue in this comparative example includes the following steps: S1. After calcining coal gangue at 700℃ for 0.5h, calcined coal gangue is obtained. S2. Calcined coal gangue and acrylic acid-modified polyester resin were added to ethyl acetate and mixed at 40°C for 3 hours, then dried to obtain pretreated coal gangue. The acrylic-modified polyester resin is 5% of the coal gangue mass, and the mass-volume ratio of coal gangue to ethyl acetate is 1g:9mL.

[0037] Comparative Example 2 Compared with Example 4, the only difference in this comparative example is the preparation method of the pretreated coal gangue. The preparation method of the pretreated coal gangue in this comparative example includes the following steps: S1. After calcining coal gangue at 700℃ for 0.5h, calcined coal gangue is obtained. S2. Calcined coal gangue and polyester-modified acrylic resin are added to ethyl acetate and mixed at 40°C for 3 hours. After drying, pretreated coal gangue is obtained. The polyester-modified acrylic resin accounts for 5% of the mass of coal gangue, and the mass-volume ratio of coal gangue to ethyl acetate is 1g:9mL.

[0038] Comparative Example 3 Compared with Example 4, the only difference in this comparative example is that no modifier is added.

[0039] Experimental Example The properties of the coal gangue pavement concrete in Examples 1-10 and Comparative Examples 1-3 were determined using the following methods: (1) The compressive strength, splitting tensile strength and water absorption of coal gangue pavement concrete were determined according to the test methods in GB / T 50081-2019 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". The loading rate was 0.5 MPa / s when the compressive strength was measured and 0.05 MPa / s when the splitting tensile strength was measured. The test specimens used for the compressive strength, splitting tensile strength and water absorption were all 100 mm × 100 mm × 100 mm cubes cured for 28 days. (2) The sulfate resistance and frost resistance were determined with reference to GB / T 50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete". The slow freezing method was selected for the frost resistance test. The samples used for sulfate resistance and frost resistance were 100mm×100mm×100mm cubes cured for 28 days. The measurement results are shown in Tables 1-4.

[0040] Table 1. Results of compressive strength test for coal gangue pavement concrete.

[0041] As shown in Table 1, the compressive strength of the coal gangue pavement concrete in Examples 1-7 is higher than that in Comparative Examples 1-3, indicating that the use of acrylic acid modified polyester resin and polyester modified acrylic resin to treat coal gangue in this invention can improve the compressive strength of coal gangue pavement concrete.

[0042] Table 2. Results of splitting tensile strength test of concrete pavement made from coal gangue.

[0043] As shown in Table 2, the splitting tensile strength of the coal gangue pavement concrete in Examples 8-10 is higher than that in Examples 1 and 4-5, indicating that the addition of pretreated nano-silica in the modifier of the present invention can improve the splitting tensile strength of coal gangue pavement concrete.

[0044] Table 3. Results of water absorption rate determination for coal gangue pavement concrete.

[0045] As shown in Table 3, the water absorption rate of coal gangue pavement concrete in Examples 8-10 is lower than that in Example 1, indicating that the addition of pretreated nano-silica in the modifier of the present invention can reduce the water absorption rate of coal gangue pavement concrete.

[0046] Table 4. Test results of erosion resistance and frost resistance of coal gangue pavement concrete.

[0047] As shown in Table 4, the coal gangue pavement concrete in this invention also has high erosion resistance and frost resistance, which can extend the service life of the coal gangue pavement concrete and reduce maintenance costs.

[0048] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-performance coal gangue pavement concrete, characterized in that, The raw materials include the following components by weight: 145-150 parts coal gangue, 135-145 parts sand, 25-30 parts water, 45-55 parts cement, 10-15 parts fly ash, 25-30 parts modifier, and 0.3-0.5 parts water-reducing agent. The coal gangue is pretreated coal gangue, which is obtained by treating coal gangue with acrylic acid-modified polyester resin and polyester-modified acrylic resin; the hydroxyl value of the acrylic acid-modified polyester resin is 7 mg KOH / g; the hydroxyl value of the polyester-modified acrylic resin is 4 mg KOH / g. The raw materials for the modifier include nano-silica and steel fibers.

2. The high-performance coal gangue pavement concrete according to claim 1, characterized in that, The mass ratio of the acrylic-modified polyester resin to the polyester-modified acrylic resin is 5:2~3.

3. The high-performance coal gangue pavement concrete according to claim 1, characterized in that, The combined mass of the acrylic-modified polyester resin and the polyester-modified acrylic resin is 3% to 6% of the mass of the coal gangue.

4. The high-performance coal gangue pavement concrete according to claim 1, characterized in that, The method for preparing the pretreated coal gangue includes the following steps: S1. After calcining coal gangue, calcined coal gangue is obtained. S2. Acrylic acid-modified polyester resin and calcined coal gangue are added to ethyl acetate and mixed to obtain a mixture; S3. Add polyester-modified acrylic resin to the mixture, mix, and then dry to obtain pretreated coal gangue.

5. The high-performance coal gangue pavement concrete according to claim 1, characterized in that, The raw materials for the modifier also include trimethylchlorosilane and methyl biphenyl-4-carboxylic acid.

6. The high-performance coal gangue pavement concrete according to claim 5, characterized in that, The mass ratio of the nano-silica, steel fiber, trimethylchlorosilane, and biphenyl-4-carboxylic acid methyl ester is 20:10:0.5:0.1~0.

2.

7. The high-performance coal gangue pavement concrete according to claim 5, characterized in that, The method for preparing the modifier includes the following steps: adding nano-silica, trimethylchlorosilane and biphenyl-4-carboxylic acid methyl ester into a solution, mixing and drying to obtain pretreated nano-silica; mixing the pretreated nano-silica with steel fibers to obtain the modifier.

8. The high-performance coal gangue pavement concrete according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate water-reducing agent.

9. A high-performance coal gangue pavement concrete according to claim 1, characterized in that, The cement is P.O42.5 silicate cement.

10. A method for preparing high-performance coal gangue pavement concrete, used to prepare the high-performance coal gangue pavement concrete as described in any one of claims 1 to 9, characterized in that, Includes the following steps: After the raw materials are mixed evenly, high-performance coal gangue pavement concrete is obtained.

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