Plain concrete for roadbed slope protection and preparation method thereof

Abstract

The present application relates to the field of road construction technology, and specifically discloses a plain concrete for roadbed slope protection and a preparation method thereof. The plain concrete is cast by a concrete mixture, and the concrete mixture includes the following components in parts by weight: 137-145 parts of Portland cement, 112-116 parts of fly ash, 735-755 parts of sand, 1403-1423 parts of crushed stone, 50-70 parts of fired brick particles, 105-109 parts of water, 2-2.4 parts of water reducer, and 1.2-4.8 parts of modified fiber, wherein the modified fiber is an acrylic fiber with a carboxyl group on the surface. The scheme of the present application can reduce the total amount of water exudation channels remaining inside the plain concrete, thereby reducing the impact of the water exudation channels on the freeze-thaw resistance of the plain concrete, helping to reduce the freeze-thaw damage of the plain concrete, and improving the protective effect of the plain concrete on the slope.

Description

Technical Field

[0001] The present application relates to the technical field of road construction, and more specifically, to a plain concrete for roadbed slope protection and a preparation method thereof. Background Art

[0002] During roadbed construction, slope protection is often necessary to limit weathering and spalling of rock and soil on the slope, reduce weathering damage, and mitigate dangerous phenomena such as rockfalls. Numerous slope protection methods exist, including rockfill, stone masonry, plain concrete, and wire cages. Plain concrete is currently the most commonly used method for slope protection.

[0003] In the related art, there is a kind of plain concrete designed according to the strength grade of C20. This plain concrete is cast by concrete mixture, and the concrete mixture includes the following components by weight: 137 parts of cement, 112 parts of fly ash, 735 parts of sand, 1453 parts of crushed stone, 105 parts of water, and 2 parts of admixture.

[0004] Regarding the aforementioned related technologies, the inventors believe that the concrete mixtures used in these technologies are prone to bleeding during construction, leaving numerous bleeding channels in the hardened plain concrete. If these solutions are used to construct plain concrete for slope protection, freeze-thaw damage is likely to occur, compromising the concrete's protective effectiveness. Summary of the Invention

[0005] Plain concrete used in related art is prone to water seepage. If plain concrete for slope protection is constructed according to the solutions described in related art, the resulting water seepage channels can easily lead to freeze-thaw damage in the plain concrete, affecting its protective effect on the slope. To address this shortcoming, the present application provides plain concrete for roadbed slope protection and a preparation method thereof.

[0006] In a first aspect, the present application provides a plain concrete for roadbed slope protection, which adopts the following technical solution:

[0007] Disclosed is plain concrete for roadbed slope protection. The plain concrete is cast by a concrete mixture, wherein the concrete mixture comprises the following components in parts by weight: 137-145 parts of Portland cement, 112-116 parts of fly ash, 735-755 parts of sand, 1403-1423 parts of crushed stone, 50-70 parts of sintered brick particles, 105-109 parts of water, 2-2.4 parts of a water reducer, and 1.2-4.8 parts of modified fiber, wherein the modified fiber is acrylic fiber with carboxyl groups on the surface.

[0008] By adopting the above technical solution, the present application adjusts the formula of the concrete mixture, replaces part of the crushed stone with fired brick particles, and incorporates modified fibers into the concrete mixture. In the concrete mixture of the present application, the fired brick particles can play a water-absorbing role, so that the total amount of free water in the concrete mixture decreases, reducing the formation of water seepage channels. The modified fibers can be distributed in the cement paste and undergo electrostatic adsorption with the mineral phase in the cement paste, thereby enhancing the cohesion of the cement paste and helping to reduce the precipitation of water. By constructing plain concrete according to the method of the present application, the total amount of water seepage channels remaining inside the plain concrete can be reduced, thereby reducing the impact of the water seepage channels on the freeze-thaw resistance of the plain concrete, helping to reduce the freeze-thaw damage of the plain concrete, and improving the protective effect of the plain concrete on the slope.

[0009] Preferably, the fired brick particles include waste clay brick particles, and the waste clay brick particles are obtained by crushing waste clay bricks.

[0010] By adopting the above technical solution, waste clay bricks are one of the main types of construction waste and have certain water absorption properties. By crushing the waste clay bricks into particles and adding them as sintered brick particles to the concrete mixture, their water absorption properties can be used to control the bleeding phenomenon and realize the resource utilization of waste clay bricks.

[0011] Preferably, the saturated water absorption rate of the waste clay brick particles is 12-16%.

[0012] By adopting the above technical solution, the saturated water absorption rate of waste clay brick particles is generally within the range of 8-16%. However, according to the ratio of this application, when the saturated water absorption rate of waste clay brick particles is less than 8%, it is relatively difficult to fully suppress water bleeding in plain concrete. Therefore, this application optimizes the saturated water absorption rate of waste clay bricks, which helps reduce the impact of water bleeding channels on the freeze-thaw resistance of plain concrete and improves the freeze-thaw resistance of plain concrete.

[0013] Preferably, the sintered brick particles include red mud brick particles, which are prepared according to the following method: red mud and auxiliary materials are mixed and ball-milled, and then dried and sieved to obtain raw material powder; the raw material powder is mixed with water and pressed into shape to obtain a green body; the green body is calcined, and the cooled calcined product is crushed to obtain red mud brick particles.

[0014] By adopting the above technical solution, the present application prepares green bricks using red mud as the main raw material, and obtains red mud brick particles with red mud as the main component through sintering and crushing. The method of the present application can provide a new way to obtain sintered brick particles when waste clay bricks are difficult to obtain, and can realize the resource utilization of red mud, a highly polluting solid waste, helping to reduce the pressure caused by red mud on the ecological environment.

[0015] Preferably, the auxiliary material includes slag, and the amount of the slag is 10-25% of the weight of the red mud.

[0016] By adopting the above technical solution, when slag is used as an auxiliary material, the water absorption rate of red mud brick particles can be improved to a certain extent, thereby improving the absorption effect of sintered brick particles on free water, helping to reduce the impact of water seepage channels on the freeze-thaw resistance of plain concrete, and improving the freeze-thaw resistance of plain concrete.

[0017] Preferably, the amount of the slag is 18-25% by weight of the red mud.

[0018] By adopting the above technical solution, the dosage range of slag is optimized, which helps to reduce the impact of water seepage channels on the freeze-thaw resistance of plain concrete and improve the freeze-thaw resistance of plain concrete.

[0019] Preferably, the components of the concrete mixture also include a calcium oxide expansion agent.

[0020] By adopting the above technical solution, the expansion mechanism of the calcium oxide expansive agent is to react with water to form calcium hydroxide, which undergoes a certain degree of volume expansion. The addition of the calcium oxide expansive agent can consume free water to a certain extent and block the seepage channels through volume expansion. The calcium hydroxide formed by the expansion of the calcium oxide can also continue to react with fly ash and increase the total amount of gel phase in the concrete mixture. The gel phase can also have a certain blocking effect on the seepage channels. Therefore, the addition of the calcium oxide expansive agent helps to fully reduce the impact of the seepage channels on the freeze-thaw resistance of plain concrete and improve the freeze-thaw resistance of plain concrete.

[0021] Preferably, the modified fiber is prepared according to the following method:

[0022] Acrylic fiber, sodium hydroxide, a surfactant and water are mixed to obtain a reaction solution, the reaction solution is heated, and then neutralized and titrated with hydrochloric acid. After titration to an endpoint, the reaction solution is filtered, and the filtered fiber is acid-washed and dried to obtain a modified fiber.

[0023] By adopting the above technical solution, the present application performs alkaline hydrolysis on acrylic fiber under heating conditions with the assistance of a surfactant in an alkaline environment provided by sodium hydroxide, hydrolyzing the nitrile groups to form carboxyl groups, which then undergo a neutralization reaction with the sodium hydroxide. Subsequently, the carboxyl groups are restored through acid washing to obtain a modified fiber.

[0024] Preferably, the surfactant is tetradecyldimethylbenzyl ammonium chloride or sodium dodecylbenzenesulfonate.

[0025] By adopting the above-mentioned technical solution, the present application preferably selects the specific types of surfactants used in the preparation of modified fibers, among which tetradecyl dimethyl benzyl ammonium chloride can improve the hydrolysis effect of acrylic fibers, thereby obtaining modified fibers with a higher degree of hydrolysis, which helps to fully improve the cohesion of cement slurry and reduce the precipitation of water, thereby reducing the impact of water seepage channels on the freeze-thaw resistance of plain concrete.

[0026] In a second aspect, the present application provides a method for preparing plain concrete for roadbed slope protection, which adopts the following technical solution.

[0027] A method for preparing plain concrete for roadbed slope protection comprises the following steps:

[0028] (1) Mix any of the above concrete mixtures and set aside;

[0029] (2) Before the concrete mixture begins to set, the concrete mixture is poured into a mold and then cured;

[0030] (3) After the concrete mixture has been cured to a specified age, the formwork is removed to obtain plain concrete for roadbed slope protection.

[0031] By employing the above-mentioned technical solution, the present applicant prepared a concrete mixture containing sintered brick particles and modified fibers, and further prepared plain concrete for roadbed slope protection. Due to the synergistic effect of the sintered brick particles and modified fibers, fewer water seepage channels remain within the plain concrete, thereby reducing the impact of water seepage and imparting stronger freeze-thaw resistance to the plain concrete.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. By constructing plain concrete according to the method of the present application, the total amount of water seepage channels remaining inside the plain concrete can be reduced, thereby reducing the impact of the water seepage channels on the freeze-thaw resistance of the plain concrete, helping to reduce freeze-thaw damage to the plain concrete and improving the protective effect of the plain concrete on the slope.

[0034] 2. In the present application, the components of the concrete mixture preferably also include a calcium oxide expansion agent. In addition to consuming free water and blocking water seepage channels by volume expansion, the addition of the calcium oxide expansion agent can also increase the total amount of gel phase in the concrete mixture and improve the blocking effect on water seepage channels, thereby helping to fully reduce the impact of water seepage channels on the freeze-thaw resistance of plain concrete and improve the freeze-thaw resistance of plain concrete. DETAILED DESCRIPTION

[0035] The present application is further described in detail below with reference to the Examples, Preparation Examples and Comparative Examples. The raw materials involved in the present application can all be obtained commercially.

[0036] Preparation example of red mud brick particles

[0037] In the following preparation examples, the main chemical components (mass fractions) of the red mud, construction waste soil, and slag used are shown in Table 1.

[0038] Table 1 Main chemical components of red mud, construction waste and slag

[0039] sample Silicon dioxide / % Alumina / % Iron oxide / % Sodium oxide / % red mud 12.6 23.8 44.6 5.2 Construction waste 57.6 18.9 3.7 0.2 slag 46.8 32.6 12.9 /

[0040] The following is an explanation using Preparation Example 1.

[0041] Preparation Example 1

[0042] In this preparation example, red mud brick particles are prepared according to the following method: red mud and auxiliary materials are mixed and ball-milled, and then dried and passed through an 80-mesh standard sieve to obtain raw material powder. The auxiliary material is construction waste, and the amount of the auxiliary material is 10% of the weight of the red mud; the raw material powder and water are mixed in a weight ratio of 10:1 and pressed at a molding pressure of 5 MPa, and the holding time is set to 1 minute. After the pressing is completed, a green body is obtained; the green body is preheated at 110°C for 30 minutes, and then the green body is heated to 900°C at a rate of 10°C / min, and then the green body is calcined at 900°C for 1 hour, and then the calcined product is allowed to cool naturally, and the cooled calcined product is crushed to obtain red mud brick particles.

[0043] Preparation Example 2

[0044] The difference between this preparation example and preparation example 1 is that the auxiliary material is slag.

[0045] As shown in Table 2, the difference between Preparation Examples 2-6 is that the percentage of the amount of auxiliary materials used in the red mud weight (hereinafter referred to as the auxiliary material ratio) is different.

[0046] Table 2 Proportion of auxiliary materials

[0047]

[0048] Preparation example of modified fiber

[0049] The following is an explanation using Preparation Example 7 as an example.

[0050] Preparation Example 7

[0051] In this preparation example, a modified fiber was prepared according to the following method: acrylic fiber, sodium hydroxide, a surfactant, and water were mixed to obtain a reaction solution, the reaction solution was heated, and then neutralized and titrated with hydrochloric acid. After titration to the endpoint, the reaction solution was filtered, and the filtered fiber was washed and dried to obtain the modified fiber. The acrylic fiber had a specification of 1.5D x 38mm, the weight ratio of acrylic fiber to sodium hydroxide was 4:3, and the weight ratio of acrylic fiber to surfactant was 1:2. The surfactant was sodium dodecylbenzenesulfonate. The reaction solution was heated at 90°C for 2 hours, the hydrochloric acid concentration was 1.2 mol / L, and the pH at the titration endpoint was 6.

[0052] Preparation Example 8

[0053] The difference between this preparation example and preparation example 7 is that the surfactant is tetradecyldimethylbenzyl ammonium chloride.

[0054] Example

[0055] Examples 1-5

[0056] The following description will be made using Example 1 as an example.

[0057] Example 1

[0058] This embodiment provides plain concrete for roadbed slope protection, which is cast from a concrete mixture comprising the following components: 137 kg of Portland cement, 112 kg of fly ash, 735 kg of sand, 1403 kg of crushed stone, 50 kg of fired brick particles, 105 kg of water, 2 kg of a polycarboxylate superplasticizer, and 1.2 kg of modified fiber. The Portland cement is PO4 2.5 Portland cement, the fly ash is Class I fly ash, the sand is Zone 2 sand with a fineness modulus of 2.7, the crushed stone and fired brick particles are continuously graded from 5 to 31.5 mm, and the polycarboxylate superplasticizer has a water reduction rate of 28.4%. The fired brick particles are particles converted from waste clay with a saturated water absorption rate of 8%. The modified fiber was prepared according to the method of Preparation Example 7.

[0059] This embodiment also provides a method for preparing plain concrete for roadbed slope protection, comprising the following steps:

[0060] (1) Mix the above concrete mixture and set aside;

[0061] (2) Before the concrete mixture begins to set, the concrete mixture is poured into a mold and then cured;

[0062] (3) After the concrete mixture has been cured to a specified age, the formwork is removed to obtain plain concrete for roadbed slope protection.

[0063] As shown in Table 3, the differences between Examples 1-5 mainly lie in the different raw material ratios of the concrete mixtures.

[0064] Table 3 Raw material ratio

[0065]

[0066] Examples 6-9

[0067] As shown in Table 4, the difference between Examples 6-9 and Example 5 is that the saturated water absorption rates of the waste clay brick particles are different.

[0068] Table 4 Saturated water absorption of waste clay brick particles

[0069] sample Example 5 Example 6 Example 7 Example 8 Example 9 Saturated water absorption / % 8 10 12 14 16

[0070] Example 10

[0071] The difference between this embodiment and embodiment 9 is that the fired brick particles are red mud brick particles prepared according to the method of preparation example 1.

[0072] Examples 11-15

[0073] As shown in Table 5, Examples 11-15 differ from Example 10 in that the preparation examples of the red mud brick particles are different.

[0074] Table 5 Preparation example of red mud brick particles

[0075] sample Preparation Example Example 10 Preparation Example 1 Example 11 Preparation Example 2 Example 12 Preparation Example 3 Example 13 Preparation Example 4 Example 14 Preparation Example 5 Example 15 Preparation Example 6

[0076] Example 16

[0077] The difference between this embodiment and embodiment 15 is that the components of the concrete mixture also include a calcium oxide expansion agent, and the amount of the calcium oxide expansion agent is 1% of the total weight of the Portland cement and fly ash.

[0078] Example 17

[0079] The difference between this embodiment and Example 16 is that the modified fiber is prepared according to the method of Preparation Example 8.

[0080] Comparative Example

[0081] Comparative Example 1

[0082] A plain concrete is cast from a concrete mixture comprising the following components by weight: 137 parts Portland cement, 112 parts fly ash, 735 parts sand, 1453 parts crushed stone, 105 parts water, and 2 parts admixture. The Portland cement is P.O.42.5 Portland cement, the fly ash is Class I fly ash, the sand is Zone 2 sand with a fineness modulus of 2.7, and the crushed stone is continuously graded from 5 to 31.5 mm. The admixture is a polycarboxylate water reducer with a water reduction rate of 28.4%.

[0083] Comparative Example 2

[0084] The difference between this comparative example and Example 1 is that all the fired brick particles in the concrete mixture are replaced by crushed stone.

[0085] Comparative Example 3

[0086] The difference between this comparative example and Example 1 is that all modified fibers in the concrete mixture are replaced with acrylic fibers.

[0087] Performance testing methods

[0088] 100 mm × 100 mm × 100 mm cubic specimens were prepared using the concrete mixtures of the Examples and Comparative Examples. Freeze-thaw cycle conditions were then set according to the requirements of the rapid freezing method described in the "GB / T 50082-2009 Standard for Test Methods for Long-term Properties and Durability of Ordinary Concrete". The compressive strength loss rate after 300 freeze-thaw cycles was tested. The ratio of the compressive strength loss rate of the specimens of the Examples and Comparative Examples to the compressive strength loss rate of the specimens of Comparative Example 1 was calculated and recorded as the relative freezing damage rate. The results are shown in Table 6.

[0089] Table 6 Relative freezing damage rate

[0090]

[0091]

[0092] Combining Examples 1-5 and Comparative Example 1 and Table 6, it can be seen that the relative freezing damage rates measured in Examples 1-5 are all lower than those in Comparative Example 1, indicating that the plain concrete of the present application loses relatively less compressive strength under the same freeze-thaw cycle conditions and has better freeze-thaw resistance.

[0093] Combining Example 1 and Comparative Example 2 with Table 6, it can be seen that the relative freezing damage rate measured in Example 1 is lower than that in Comparative Example 2, indicating that when the components of the concrete mixture do not include fired brick particles, the water absorption effect of the fired brick particles cannot be used to reduce water bleeding. Therefore, the free water in the concrete mixture is relatively large, resulting in poor freeze-thaw resistance of the plain concrete and a large loss of compressive strength after freeze-thaw cycles.

[0094] Combining Example 1 and Comparative Example 3 with Table 6, it can be seen that the relative freezing damage rate measured in Example 1 is lower than that in Comparative Example 3, indicating that when the components of the concrete mixture do not include modified fibers, the cohesion of the cement paste is limited, and free water is relatively easy to precipitate from the cement paste and cause bleeding, resulting in poor freeze-thaw resistance of the plain concrete and a significant loss of compressive strength after freeze-thaw cycles.

[0095] Combining Example 5 and Examples 6-9 with Table 6, it can be seen that when the saturated water absorption rate of the waste clay brick particles is 12-16%, the plain concrete for roadbed slope protection loses less strength after freeze-thaw cycles and has better freeze-thaw resistance.

[0096] From Example 9, Example 10 and Table 6, it can be seen that the red mud brick particles prepared in the present application can not only replace waste clay particles, but also more fully improve the freeze-thaw resistance of plain concrete for roadbed slope protection.

[0097] Combining Example 10, Examples 11-15, and Table 6, it can be seen that the red mud brick particles added with slag have a significant improvement effect on the freeze-thaw resistance of plain concrete, and when the amount of slag is 18-25% of the weight of the red mud, the freeze-thaw resistance of the plain concrete is better, and the strength loss after experiencing freeze-thaw cycles is less.

[0098] From Example 15 and Example 16 and Table 6, it can be seen that the addition of a calcium oxide expansive agent to the concrete mixture can reduce the strength loss of the plain concrete after freeze-thaw cycles. This indicates that the calcium oxide expansive agent improves the blocking effect of the water seepage channel by consuming free water, expanding the volume, and increasing the total amount of the gel phase, thereby helping to fully reduce the impact of the water seepage channel on the freeze-thaw resistance of the plain concrete and improve the freeze-thaw resistance of the plain concrete.

[0099] Combining Examples 16 and 17 with Table 6, it can be seen that tetradecyldimethylbenzyl ammonium chloride is more effective than sodium dodecylbenzenesulfonate in improving the hydrolysis of acrylic fiber. Therefore, Preparation Example 8 can produce modified fibers with a higher degree of hydrolysis. Therefore, the use of the modified fibers of Preparation Example 8 helps to significantly improve the cohesion of the cement paste and reduce water precipitation, thereby reducing the impact of water seepage channels on the freeze-thaw resistance of plain concrete.

[0100] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A plain concrete for roadbed slope protection, characterized in that: The plain concrete is cast by a concrete mixture, which includes the following components in parts by weight: 137-145 parts of Portland cement, 112-116 parts of fly ash, 735-755 parts of sand, 1403-1423 parts of crushed stone, 50-70 parts of sintered brick particles, 105-109 parts of water, 2-2.4 parts of a water reducer, and 1.2-4.8 parts of modified fiber, wherein the modified fiber is acrylic fiber with carboxyl groups on the surface.

2. The plain concrete for roadbed slope protection according to claim 1, characterized in that: The fired brick particles include waste clay brick particles, which are obtained by crushing waste clay bricks.

3. The plain concrete for roadbed slope protection according to claim 2, characterized in that: The saturated water absorption rate of the waste clay brick particles is 12-16%.

4. The plain concrete for roadbed slope protection according to claim 1, characterized in that: The sintered brick particles include red mud brick particles, and the red mud brick particles are prepared according to the following method: The red mud and auxiliary materials are mixed and ball-milled, then dried and sieved to obtain raw material powder; the raw material powder is mixed with water and pressed into shape to obtain a green body; the green body is calcined, and the cooled calcined product is crushed to obtain red mud brick particles.

5. The plain concrete for roadbed slope protection according to claim 4, characterized in that: The auxiliary material includes slag, and the amount of the slag is 10-25% of the weight of the red mud.

6. The plain concrete for roadbed slope protection according to claim 5, characterized in that: The amount of the slag is 18-25% of the weight of the red mud.

7. The plain concrete for roadbed slope protection according to claim 1, characterized in that: The components of the concrete mixture also include calcium oxide expansion agent.

8. The plain concrete for roadbed slope protection according to claim 1, characterized in that: The modified fiber is prepared according to the following method: Acrylic fiber, sodium hydroxide, a surfactant and water are mixed to obtain a reaction solution, the reaction solution is heated, and then neutralized and titrated with hydrochloric acid. After titration to an endpoint, the reaction solution is filtered, and the filtered fiber is acid-washed and dried to obtain a modified fiber.

9. The plain concrete for roadbed slope protection according to claim 8, characterized in that: The surfactant is tetradecyldimethylbenzyl ammonium chloride or sodium dodecylbenzenesulfonate.

10. A method for preparing plain concrete for roadbed slope protection, characterized in that: The following steps are involved: (1) Mixing the concrete mixture according to any one of claims 1 to 9 and setting aside; (2) Before the concrete mixture begins to set, pour the concrete mixture into the mold and then cure the concrete mixture; (3) After the concrete mixture has been cured to a specified age, the formwork is removed to obtain plain concrete for roadbed slope protection.

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