Preparation method of green and recyclable cable trench backfill material

Abstract

The invention provides a preparation method of a green and recoverable cable trench backfill material, which comprises the following specific steps: premixing bentonite, limestone powder and a fine sand solid dry material for 3 minutes by using a stirrer to obtain a mixed dry material; mixing water, a water reducing agent and sodium silicate to prepare a mixed solution; mixing the mixed dry material, the mixed solution and high-molecular water-absorbent resin to obtain a mixture A; the preparation method comprises the following steps: adding the raw materials into engineering slurry, adding a proper amount of water according to the water content of the engineering slurry, and mixing to obtain the slurry-shaped backfill material. The initial fluidity of the backfill material prepared from the engineering slurry is larger than or equal to 180 mm, the backfill material has good initial fluidity, and the problems of maintenance difficulty and the like are solved. The cost of the cable trench backfill material is effectively reduced, and the water retention rate of the filler can be improved.

Description

Technical Field

[0001] The invention relates to the field of electric power construction, and in particular to a method for preparing a green and recyclable cable trench backfill material. Background Art

[0002] At present, cable trenches of 110kV and above in China Southern Power Grid are filled with river sand for fire protection. The advantage is that the sand is granular, easy to landfill and transport, and also convenient to dig out and reuse during cable repair. It has a certain carrying capacity, which can support the external load above the cable trench while protecting the cable. In general, the above characteristics of river sand are mainly its granular shape and the small adhesion between particles, which facilitates the sliding between particles and is easy to construct and repair.

[0003] With the strengthening of the concept of ecological protection in society, the advantages of river sand are no longer obvious. The reason is that river sand is a non-renewable resource. The mining of river sand has an impact on the environment, and restricting its mining leads to an increase in the price of river sand. In addition, the porosity between river sand is large, resulting in poor water retention and it is easy to dry up. Dried river sand is very unfavorable for the heat dissipation of cables. Secondly, the existing cable trench fillers also have disadvantages such as difficulty in maintenance.

[0004] my country produces about 2 billion tons of construction waste every year, which is 10 times the amount of domestic waste. Among them, construction slag and engineering mud account for about 70% to 80% of construction waste. More importantly, the recycling rate of this type of resources is low. The existing treatment method is mainly to dehydrate it into mud cakes by natural air drying, extrusion, etc., and then transport it to the processing plant for waste mud treatment. There are disadvantages such as low efficiency, high cost and long cycle. There is even the phenomenon of illegal discharge and random discharge of waste mud, which causes damage to the ecological environment of surrounding rivers and lakes and endangers the drinking water safety of residents. Although the resource utilization of engineering mud has been widely studied, due to the low content of active substances in engineering mud, if it is required for stable engineering application, it needs to be screened, activated and other complex operations to improve its gelling properties and material strength. These operations make the resource utilization of engineering waste not economical and practical. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a method for preparing a green and recyclable cable trench backfill material. The backfill material prepared by engineering mud has a fluidity of ≥180mm and has self-leveling characteristics, which solves the problem of maintenance difficulties; it not only effectively reduces the cost of cable trench backfill materials, but also improves the water retention rate of the filler.

[0006] The purpose of the present invention is achieved through the following technical solutions: A method for preparing a green and recyclable cable trench backfill material comprises the following specific steps: (1) Premix bentonite, limestone powder and fine sand solid dry materials using a mixer for 3 minutes to obtain a mixed dry material; mix water, a water reducing agent and sodium silicate to prepare a mixed solution; (2) Mixing the mixed dry material prepared in step (1) with the mixed solution and the polymer water-absorbing resin to obtain a mixture A; (3) Add the mixture A prepared in step (2) to the engineering mud, add an appropriate amount of water according to the water content of the engineering mud, and then mix them to obtain a slurry-like backfill material.

[0007] Preferably, the weight proportion of the bentonite is 1100-2640 parts.

[0008] More preferably, the weight portion of the bentonite is 2640 parts.

[0009] Preferably, the weight portion of the limestone powder is 55-132 parts.

[0010] More preferably, the weight portion of the limestone powder is 132 parts.

[0011] Preferably, the weight proportion of the fine sand is 4400-10560 parts.

[0012] More preferably, the weight portion of the fine sand is 10560 parts.

[0013] Preferably, the weight portion of the water reducing agent is 22-54 parts.

[0014] More preferably, the weight portion of the water reducing agent is 54 parts.

[0015] Preferably, the weight portion of the sodium silicate is 28-68 parts.

[0016] More preferably, the weight portion of the sodium silicate is 68 parts.

[0017] Preferably, the weight portion of water is 2000-4000 parts.

[0018] More preferably, the weight portion of water is 4000 parts.

[0019] Preferably, in step 2), the weight portion of the polymer water-absorbing resin is 11-28 parts.

[0020] More preferably, in step 2), the weight portion of the polymer water-absorbing resin is 28 parts.

[0021] Preferably, in step 3), the weight of the engineering mud is 2668-14504 parts. More preferably, in step 3), the weight of the engineering mud is 2668 parts, and the weight of the water is 1440 parts.

[0022] Preferably, the backfill material as a whole contains 5440-9432 parts of water.

[0023] More preferably, the backfill material as a whole contains 9432 parts of water.

[0024] Preferably, the moisture content of the backfill material is 30%-40%.

[0025] The present invention has the following advantages and beneficial effects compared with the prior art: (1) The present invention discloses a method for preparing a green and recyclable cable trench backfill material. The method uses engineering mud as raw material to carry out a gelling reaction with solid waste under the action of an alkaline activator and an admixture to produce a solid aggregate similar to river sand, and then a certain amount of moisture is maintained by a polymer absorbent resin (SAP) to finally become a cable trench backfill material. The raw material of the backfill material is solid waste, which has good environmental significance and economic benefits.

[0026] (2) The main components of engineering mud are clay, water and silt sand. Although most engineering muds are inactive, their mineral composition contains high levels of SiO2, CaO and Al2O3, making them comparable to potential hydraulic materials (such as fly ash, silica fume and blast furnace slag). Through the stimulation of alkaline solutions, some engineering muds can have certain activity and react with solid waste to form gel-like hydration products such as hydrated calcium silicate, hydrated calcium sulfate and hydrated calcium aluminate. These gel-like hydration products The unreacted engineering waste can be bonded together to form a spatially stable mesh structure, which can constitute the main body of the backfill material. The main body is similar to a sand particle aggregate. Compared with river sand, there is a controllable bonding force between the particles, which ensures that the damaged cable can be easily repaired while bearing the upper load; secondly, the material has good fluidity at the initial stage of the reaction, with a fluidity of ≥180mm, and has self-leveling characteristics. It can fill the gaps in the cable trench like water, improve the water-locking property of the filler, and enhance the protection effect on the cable. (3) The cable trench backfill material provided by the present invention is divided into three components: mixture A, engineering mud and water. The materials can be flexibly configured according to weather and working conditions to cope with complex construction conditions and reduce the probability of unsuitable construction and error rework. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the process flow of the present invention.

[0028] Figure 2 This is a picture of the backfill material of the present invention before solidification.

[0029] Figure 3 This is a picture of the backfill material of the present invention after solidification.

[0030] Figure 4 This is a picture of the backfill material after it has dried and hardened. DETAILED DESCRIPTION

[0031] The purpose of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the implementation mode of the present invention is not therefore limited to the following embodiments.

[0032] Example 1 This embodiment provides a method for preparing a green, recyclable cable trench backfill material, and the specific steps are as follows: 1) Raw material processing: 2640 parts of bentonite, 132 parts of limestone powder, and 10560 parts of fine sand solid dry materials were premixed in a mixer for 3 minutes. At the same time, 4000 parts of water, 54 parts of water reducing agent, and 68 parts of sodium silicate were taken to prepare a mixed solution; 2) Preparation of effective components: The solid dry blend, the mixed solution and 28 parts of SAP in step 1) are mixed in a mixer to obtain a mixture A; 3) Preparation of backfill material: Mixture A is added to 2668 parts of engineering mud, and according to the water content of the engineering mud, an appropriate amount of water is added to make the total water content 5440 parts, and then mixed and stirred to obtain a backfill material slurry; Example 2 This embodiment provides a method for preparing a green, recyclable cable trench backfill material, and the specific steps are as follows: 1) Raw material processing: 1100 parts of bentonite, 55 parts of limestone powder, and 4400 parts of fine sand solid dry materials were premixed in a mixer for 3 minutes. At the same time, 2000 parts of water, 22 parts of water reducing agent, and 28 parts of sodium silicate were taken to prepare a mixed solution; 2) Preparation of effective components: The solid dry blend, the mixed solution and 11 parts of SAP in step 1) are mixed in a blender to obtain a mixture A; 3) Preparation of backfill material: Add mixture A to 14504 parts of engineering mud, add an appropriate amount of water according to the water content of the engineering mud so that the total water content is 9432 parts, and then mix and stir to obtain a backfill material slurry; Example 3 This embodiment provides a convenient method for preparing green and recyclable cable trench backfill material.

[0033] 1) Adding a mixture A prefabricated in a factory to a construction tank truck filled with construction mud, the components of the mixture being the same as those in the above-mentioned embodiment 1, and transporting the mixture to a predetermined construction site while stirring in the construction tank truck; 2) Pumping operation of cable trench backfill material is carried out, and curing treatment is performed. After the curing is completed, the backfill material described in this method is obtained.

[0034] Table 1 shows the performance data of the backfill materials prepared in Examples 1-3. It can be seen from Table 1 that Example 1 provides the optimal preparation method, which has good fluidity, moderate strength and good economic performance. The fluidity obtained is greater than 240 mm, and it has good initial fluidity after stirring. The 28d compressive strength is about 9.6 MPa, which meets the strength requirements of the cable trench backfill material. The cost of each cubic meter of backfill material is about 309.64 yuan.

[0035] Example 2 provides the most economical backfill material preparation method, the obtained fluidity is greater than 180mm, it has a certain initial fluidity after stirring, the 28d compressive strength is about 2MPa, and the cost of each cubic meter of backfill material is about 200.42 yuan. Compared with Case 1, this embodiment maximizes the mud content while satisfying the fluidity, which greatly reduces the overall manufacturing cost, but the strength will drop significantly, and due to the reduction in the content of cementitious materials, the setting time and the stability of the materials will deteriorate to a certain extent. Further increasing the mud content will cause the backfill material to lose its self-leveling characteristics, or in order to ensure fluidity, the backfill slurry will experience segregation and stratification due to excessive water content.

[0036] Embodiment 3: Mixture A is prefabricated in the factory in advance, and then added to the engineering mud. After only a short period of stirring, the pouring operation can be carried out immediately. The prepared backfill material has moderate performance. The whole process is simple to operate and takes a short time, which can greatly improve the efficiency of engineering construction. The construction process is simple and easy to operate, which can greatly improve the construction efficiency. The above specific implementation modes are preferred embodiments of the present invention and cannot be used to limit the present invention. Any other changes or other equivalent replacement methods that do not deviate from the technical solution of the present invention are included in the protection scope of the present invention.

Claims

1. A method for preparing a green and recyclable cable trench backfill material, characterized in that: The specific steps include: (1) Premix bentonite, limestone powder and fine sand solid dry materials using a mixer for 3 minutes to obtain a mixed dry material; mix water, a water reducing agent and sodium silicate to prepare a mixed solution; (2) Mixing the mixed dry material prepared in step (1) with the mixed solution and the polymer water-absorbing resin to obtain a mixture A; (3) Add the mixture A prepared in step (2) to the engineering mud, add an appropriate amount of water according to the water content of the engineering mud, and then mix them to obtain a slurry-like backfill material.

2. The method for preparing the green, recyclable cable trench backfill material according to claim 1, characterized in that: The weight portion of the bentonite is 1100-2640 parts.

3. The method for preparing the green and recyclable cable trench backfill material according to claim 1, characterized in that: The weight portion of the limestone powder is 55-132 parts.

4. The method for preparing the green, recyclable cable trench backfill material according to claim 1, characterized in that: The weight proportion of the fine sand is 4400-10560 parts.

5. The method for preparing the green and recyclable cable trench backfill material according to claim 1, characterized in that: The weight portion of the water reducing agent is 22-54 parts.

6. The method for preparing the green and recyclable cable trench backfill material according to claim 1, characterized in that: The weight portion of the sodium silicate is 28-68 parts.

7. The method for preparing the green and recyclable cable trench backfill material according to claim 1, characterized in that: The weight portion of the water is 2000-4000 parts.

8. The method for preparing the green and recyclable cable trench backfill material according to claim 1, characterized in that: In step (2), the weight portion of the polymer water-absorbing resin is 11-28 parts.

9. The method for preparing the green and recyclable cable trench backfill material according to claim 1, characterized in that: In step (3), the weight proportion of the engineering mud is 2668-14504 parts.

10. The method for preparing the green and recyclable cable trench backfill material according to claim 1, characterized in that: The backfill material as a whole contains 5440-9432 parts of water.

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