Highway concrete ditch cover and its preparation method and application

Abstract

The present invention belongs to the technical field of engineering materials and specifically relates to a highway concrete ditch cover and a preparation method and application thereof. The raw materials of the cover include, by weight, 115-135 parts of cement, 12-16 parts of silica fume, 280-290 parts of medium sand, 420-430 parts of rice stone, 0.8-1 parts of 3mm basalt fiber, 1.5-2 parts of 19mm basalt fiber, 15-20 parts of polycarboxylate water reducer, 65-70 parts of water, 55-65 parts of fluorgypsum powder, and 15-20 parts of fluorosilicate. The preparation method comprises the following steps: uniformly mixing the raw materials, and then sequentially performing the steps of pouring, vibrating, curing, and demoulding. The highway ditch cover prepared by the present invention has excellent mechanical properties and ultimate load, can reduce the thickness of the cover, and reduce weight and labor intensity while meeting standards and design requirements; and simultaneously turns waste into treasure, consumes a large amount of fluorgypsum, saves energy and resources, and complies with the national sustainable development strategy.

Description

Technical Field

[0001] The present invention belongs to the technical field of engineering materials, and in particular relates to a highway concrete ditch cover and a preparation method and application thereof. Background Art

[0002] After years of development and use, concrete trench covers have become standardized products of various sizes and specifications. The relevant standard atlases include "Trench and Cover Atlas 02J331", etc. However, due to the performance of ordinary concrete itself and the limitations of construction technology, the thickness of existing highway concrete trenches is generally not less than 60mm. The thickness of some covers with larger spans even exceeds 200mm. Due to the large thickness, the amount of concrete used is naturally large, which not only wastes resources, but also makes the finished cover very bulky, causing many inconveniences during transportation and on-site installation. Sometimes even large lifting machinery is required to complete transportation, loading and unloading and on-site installation.

[0003] Fluorogypsum is an industrial byproduct of hydrogen fluoride produced from sulfuric acid and fluorspar. Currently, most domestic fluorogypsum is simply stored or landfilled. This not only occupies a large amount of land, but also causes soluble harmful substances to dissolve in water through rainwater erosion and soaking, leading to surface and groundwater pollution. Furthermore, the accumulated fluorogypsum is exposed to sunlight and wind, generating dust pollution in the air. This large accumulation of chemical gypsum is a serious constraint on the development of the industry.

[0004] Due to its slow hydration rate and low activity, fluorgypsum is also added to concrete in a small amount as a retarder, but the dosage generally does not exceed 5%. Excessive additions not only have little effect on retarding the setting, but also cause the slow formation of ettringite in the later stages of the concrete, generating expansion stress and weakening the slurry. In short, the comprehensive utilization rate of fluorgypsum in my country is currently low.

[0005] Therefore, it is necessary to provide a highway concrete trench cover that can reduce thickness while meeting mechanical property requirements. At the same time, it is urgent to develop a method that can consume a large amount of fluorinated gypsum. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a method for preparing a highway concrete cover plate, so as to achieve the effect of reducing the thickness of the highway cover plate and consuming a large amount of fluorgypsum.

[0007] The object of the present invention is achieved through the following technical solutions:

[0008] A preparation material for a highway concrete ditch cover comprises, by weight, 115-135 parts of cement, 12-16 parts of silica fume, 280-290 parts of medium sand, 420-430 parts of rice stone, 0.8-1 part of 3mm basalt fiber, 1.5-2 parts of 19mm basalt fiber, 15-20 parts of polycarboxylate water reducer, 65-70 parts of water, 55-65 parts of fluorgypsum powder, and 15-20 parts of fluorosilicate.

[0009] Preferably, the composition comprises, by weight: 127 parts of cement, 14.7 parts of silica fume, 286 parts of medium sand, 424 parts of rice stone, 0.8 parts of 3mm basalt fiber, 1.9 parts of 19mm basalt fiber, 18 parts of polycarboxylate water reducer, 67 parts of water, 60 parts of fluorgypsum powder and 18 parts of fluorosilicate.

[0010] Furthermore, the cement is selected from P.O42.5R cement.

[0011] Furthermore, the particle size of the rice stone is 5-10 mm.

[0012] Furthermore, the basalt fiber is a general-purpose basalt fiber.

[0013] Furthermore, the fluorosilicate includes sodium fluorosilicate and magnesium fluorosilicate.

[0014] Furthermore, the mass ratio of the sodium fluorosilicate to the magnesium fluorosilicate is 1:3-4.

[0015] The present invention also provides a method for preparing a highway concrete ditch cover, comprising the following steps:

[0016] S1. Prepare the above raw materials and mix them evenly to obtain a concrete slurry;

[0017] S2. The concrete slurry is poured into the cover mold and vibrated evenly;

[0018] S3. Curing and demoulding to obtain the concrete ditch cover.

[0019] Furthermore, in step S3, the curing is performed with reference to the description in "Q / CR 2.1-2014 Railway Cable Tray Covers and Sidewalk Treads Part 1: Reactive Powder Concrete Type".

[0020] The present invention also provides a highway concrete ditch cover prepared according to the above method.

[0021] The present invention also provides application of the above-mentioned highway concrete ditch cover in construction engineering.

[0022] In the present invention, cement and fluorgypsum are used together as the cementitious materials, with the fluorgypsum dosage being approximately 50% of the cement. After the addition of fluorosilicate, the fluorosilicate acts as an active activator, significantly increasing the hydration rate of fluorgypsum, bringing its setting speed close to that of cement, thereby avoiding the adverse effects on product strength caused by the different hardening rates. Simultaneously, the fluorsilicate reacts with alkaline substances generated during the cement hydration process to produce corresponding fluorides and silicon dioxide. This, on the one hand, fills the pores in the concrete and improves the product's density. On the other hand, the fluorgypsum can, in turn, act as an activator, promoting a secondary hydration reaction between calcium hydroxide and the generated silicon dioxide formed during primary hydration, further enhancing the product's strength.

[0023] Fluorosilicate is a compound of sodium fluorosilicate and magnesium fluorosilicate. In addition to being used as an active stimulant, existing research has shown that magnesium fluorosilicate also has the effect of improving the early and late strength of concrete. In addition, sodium fluorosilicate also affects the setting speed of cement. The present invention ensures a consistent hardening rate of the cementitious material by precisely defining the ratio of sodium fluorosilicate to magnesium fluorosilicate.

[0024] In addition, the components of the present invention include basalt fibers of two sizes, 3mm and 19mm. Among them, the 3mm short fibers can control the development of capillary cracks in concrete, and the 19mm long fibers can form a three-dimensional network structure to strengthen the connection between aggregates. Under the synergistic effect of the two, the mechanical properties of the cover plate are further improved.

[0025] It should be noted that in the present invention, the ratio of cement to fluorgypsum is also particularly important. If the cement content is too high, the fluorgypsum will only act as a retarder and will not consume the fluorgypsum. If the cement content is too low, the mechanical properties of the product will not meet the requirements.

[0026] The beneficial effects of the present invention are:

[0027] 1. The highway trench cover prepared by the present invention has excellent mechanical properties and ultimate load. Under the premise of meeting standards and design requirements, the thickness of the cover can be reduced, and the weight and labor intensity can be reduced;

[0028] 2. This solution turns waste into treasure, consumes a large amount of fluorgypsum, saves energy and resources, and is in line with the national sustainable development strategy. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited to the following.

[0030] Example 1

[0031] This embodiment provides a highway concrete ditch cover with a size of 490*590*50mm.

[0032] By weight, the raw materials of the cover plate include: 127 parts of P.O42.5R cement, 14.7 parts of silica fume, 286 parts of medium sand, 424 parts of 5-10mm stone, 0.8 parts of 3mm basalt fiber, 1.9 parts of 19mm basalt fiber, 18 parts of polycarboxylic acid water reducer, 67 parts of water, 60 parts of fluorgypsum powder and 18 parts of fluorosilicate.

[0033] The basalt fiber is a general-purpose basalt fiber purchased from the market; and the fluorosilicate is compounded by sodium fluorosilicate and magnesium fluorosilicate in a mass ratio of 1:3.

[0034] The preparation method of the trench cover comprises the following steps:

[0035] S1. Mix the raw materials to obtain concrete slurry;

[0036] S2. The concrete slurry is poured into the cover mold and vibrated evenly;

[0037] S3 curing, demoulding, to obtain the concrete cover;

[0038] In step S2, the cover plate mold has a size of 490*590*50 mm, and reinforcement is provided in the mold according to a general method in the art.

[0039] In step S3, the curing is performed with reference to the description in "Q / CR 2.1-2014 Railway Cable Tray Covers and Sidewalk Treads Part 1: Reactive Powder Concrete Type".

[0040] The concrete trench cover prepared in this embodiment has been applied to highways in Guangxi Zhuang Autonomous Region, meeting the requirement that its ultimate load is greater than 65kN.

[0041] Example 2

[0042] This embodiment provides a highway concrete ditch cover with a size of 790*490*70 mm.

[0043] By weight, the raw materials of the cover plate include: 120 parts of P.O42.5R cement, 16 parts of silica fume, 280 parts of medium sand, 430 parts of 5-10mm stone, 1 part of 3mm basalt fiber, 2 parts of 19mm basalt fiber, 15 parts of polycarboxylic acid water reducer, 70 parts of water, 65 parts of fluorgypsum powder and 15 parts of fluorosilicate.

[0044] The basalt fiber is a general-purpose basalt fiber purchased from the market; and the fluorosilicate is compounded by sodium fluorosilicate and magnesium fluorosilicate in a mass ratio of 1:4.

[0045] The preparation method of the trench cover comprises the following steps:

[0046] S1. Mix the raw materials to obtain concrete slurry;

[0047] S2. The concrete slurry is poured into the cover mold and vibrated evenly;

[0048] S3 curing, demoulding, to obtain the concrete cover;

[0049] In step S2, the cover plate mold has a size of 790*490*70 mm, and reinforcement is provided in the mold according to a general method in the art.

[0050] In step S3, the curing is performed with reference to the description in "Q / CR 2.1-2014 Railway Cable Tray Covers and Sidewalk Treads Part 1: Reactive Powder Concrete Type".

[0051] The concrete trench cover prepared in this embodiment has been applied to expressways in Hunan Province, meeting the requirement that its ultimate load is greater than 70 kN.

[0052] Comparative Example 1

[0053] Comparative Example 1 provides a cover plate with the same size as Example 1. The difference from Example 1 is that the raw material components do not contain fluorosilicate, and the rest are the same.

[0054] Comparative Example 2

[0055] Comparative Example 2 provides a cover plate with the same size as Example 1. The difference from Example 1 is that the raw material components do not include 3mm basalt fiber, and the weight portion of 19mm basalt fiber is 2.7 parts. The rest are the same.

[0056] Comparative Example 3

[0057] Comparative Example 3 provides a cover plate with the same size as Example 1. The difference from Example 1 is that the raw material components do not contain 19 basalt fibers, and the weight portion of 3 mm basalt fibers is 2.7 parts. The rest are the same.

[0058] Comparative Example 4

[0059] Comparative Example 4 provides a cover plate with the same size as Example 1. The difference from Example 1 is that the number of P.O42.5R cement in the raw material components is 60 parts, the number of fluorgypsum powder is 127 parts, and the rest are the same.

[0060] Comparative Example 5

[0061] Comparative Example 5 provides a cover plate with the same size as Example 1. The difference from Example 1 is that, in the raw materials, the fluorosilicate is compounded by sodium fluorosilicate and magnesium fluorosilicate in a mass ratio of 5:1, and the rest are the same.

[0062] Due to the lack of a unified standard and the fact that the cover plate is provided with reinforcement, differences in the reinforcement structure will also lead to differences in the performance of the cover plate. To avoid errors, the present invention does not perform performance tests on the prepared cover plates. Instead, the present invention tests concrete specimens cast with the raw material components of each embodiment and comparative example with reference to the method in "Q / CR 2.1-2014 Railway Cable Trunking Cover Plates and Sidewalk Treads Part 1: Reactive Powder Concrete Type". The test results are shown in Table 1.

[0063] Table 1

[0064]

[0065] According to Table 1, after comparing Comparative Example 1 with Example 1, it can be concluded that although the proportion of fluorosilicate in the raw material components is small, its role is significant. When fluorosilicate is not included in the components, the mechanical properties and chloride ion permeability resistance of the product are relatively poor. According to Comparative Examples 2 and 3, it can be seen that the two specifications of basalt fibers have a synergistic effect in the present invention. Comparative Example 4 shows that when the amount of fluorgypsum is too large, it will have an adverse effect on the performance of the product. Comparative Example 5 changes the ratio of sodium fluorosilicate and magnesium fluorosilicate in fluorosilicate, which also leads to a decrease in performance.

[0066] Comparative Example 6

[0067] Comparative Example 6 uses the raw material components of Example 1. During the performance test, the thickness of the cast specimen is lower than that of Example 1. Specifically, a 100mm*100mm*90mm specimen is used for the compressive strength measurement (the thickness is reduced by 10mm compared with Example 1), a 100mm*100mm*390mm specimen is used for the flexural strength measurement (the thickness is reduced by 10mm compared with Example 1), and a 100mm*100mm*290mm specimen is used for the elastic modulus measurement (the thickness is reduced by 10mm compared with Example 1). The test results are shown in Table 2.

[0068] Table 2

[0069]

[0070] As shown in Table 2, even with the reduced thickness, the mechanical properties of the specimens still meet the requirements for R160 strength grade concrete in Q / CR 2.1-2014 Railway Cable Tray Covers and Sidewalk Treads Part 1: Reactive Powder Concrete Type. This shows that the present invention can reduce the thickness of the cover, thereby reducing its weight and labor intensity while meeting the standard and design requirements.

[0071] Example 3

[0072] Leaching toxicity test:

[0073] Leaching toxicity tests were conducted on concrete samples cast using the present invention, using the HJ 557-2010 standard, "Solid Waste Leaching Toxicity Leaching Method - Horizontal Oscillation Method." The results showed that the fluoride ion leaching rate from concrete at all ages was extremely low, posing no harm to the environment or human health. Specific results are shown in Table 3. (The fluoride ion limit in GB5749-2006, "Drinking Water Hygiene Standard," is less than 1 mg / L.)

[0074]

[0075] The foregoing description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Rather, the present invention can be used in various other combinations, modifications, and environments and can be modified within the scope of the concept described herein through the above teachings or techniques or knowledge in the relevant field. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention are intended to be protected by the appended claims.

Claims

1. A highway concrete ditch cover, characterized in that: The raw materials for preparation include, by weight, 115-135 parts of cement, 12-16 parts of silica fume, 280-290 parts of medium sand, 420-430 parts of rice stone, 0.8-1 parts of 3mm basalt fiber, 1.5-2 parts of 19mm basalt fiber, 15-20 parts of polycarboxylate water reducer, 65-70 parts of water, 55-65 parts of fluorgypsum powder and 15-20 parts of fluorosilicate.

2. A highway concrete ditch cover according to claim 1, characterized in that: The raw materials for preparation are calculated by weight and include: 127 parts of cement, 14.7 parts of silica fume, 286 parts of medium sand, 424 parts of rice stone, 0.8 parts of 3mm basalt fiber, 1.9 parts of 19mm basalt fiber, 18 parts of polycarboxylate water reducer, 67 parts of water, 60 parts of fluorgypsum powder and 18 parts of fluorosilicate.

3. The highway concrete ditch cover according to claim 1, characterized in that: The cement is selected from P.O42.5R cement.

4. The highway concrete ditch cover according to claim 1, characterized in that: The particle size of the rice stone is 5-10 mm.

5. The highway concrete ditch cover according to claim 1, characterized in that: The basalt fiber is a general-purpose basalt fiber.

6. The highway concrete ditch cover according to claim 1, characterized in that: The fluorosilicates include sodium fluorosilicate and magnesium fluorosilicate.

7. The highway concrete ditch cover according to claim 6, characterized in that: The mass ratio of the sodium fluorosilicate to the magnesium fluorosilicate is 1:3-4.

8. The method for preparing a highway concrete ditch cover according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1 prepare the raw materials, and mix evenly to obtain a concrete slurry; S2. The concrete slurry is poured into the cover mold and vibrated evenly; S3. Curing and demoulding to obtain the concrete trench cover.

9. A highway concrete ditch cover prepared according to the preparation method of claim 8.

10. Use of the highway concrete ditch cover according to claim 9 in construction engineering.

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