Thickening type rock-based mineral admixture and concrete

Abstract

The invention belongs to the technical field of building materials, and discloses a thickened rock-based mineral admixture and concrete. The thickened rock-based mineral admixture comprises the following raw materials in parts by weight: 75-90 parts of a rock component, 10-20 parts of an activating component and 2-5 parts of a modifying component. The rock component is ground carbonate cave slag and is selected from one of limestone, marble and dolomite. The high-activity thickening type rock-based mineral admixture is prepared by utilizing the characteristic of good hydrophilicity of the carbonate stone powder, so that the cohesiveness of the concrete is improved, and the cohesive force of the sprayed concrete and a tunnel rock wall is enhanced. Meanwhile, the hole slag produced in the tunnel excavation process is prepared into a homogenized admixture and aggregate, the homogenized admixture and aggregate are matched with other components to prepare sprayed concrete, and the sprayed concrete is completely applied to tunnel construction, so that the utilization rate of the tunnel hole slag reaches 100%, and the green production concept of taking and using the same to a tunnel is practiced; the method has the advantages of environmental protection, obvious economic benefit, stable concrete quality and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and more specifically relates to a thickening type rock-based mineral admixture and concrete. Background Art

[0002] At present, my country's engineering construction is gradually advancing to the difficult and mountainous areas of the western plateau. Tunnels account for a high proportion of linear projects such as highways and railways. The excavation of tunnels produces a large amount of tunnel slag, which is expensive to transport and maintain. The storage and disposal process occupies a large amount of land resources, and there are potential risks of secondary disasters such as landslides and mudslides, which have a huge impact on the ecological environment and people's property safety along the project. At the same time, affected by the policy of limiting river sand mining and the seasonal mining characteristics, railway engineering construction faces a serious shortage of sand and gravel resources. The inconvenient transportation conditions for mountainous projects have made the shortage of aggregate resources particularly prominent. Mechanized aggregates are made of qualified parent rocks through crushing, screening and other processes. They have the advantages of controllable output and quality and low production cost, and have gradually become the main direction of the development of green building materials. Traditional mineral admixtures such as fly ash and slag powder play an important role in ensuring the durability of concrete, but the resources of high-quality mineral admixtures are increasingly scarce, and the safe service of railway concrete is facing severe challenges. The demand for the use of new mineral admixtures to replace traditional mineral admixtures is growing. Based on the contradiction between the difficulty in disposing of huge volumes of tunnel slag in mountainous engineering construction and the shortage of bulk ground material resources, preparing tunnel slag into sand and gravel aggregates and rock-based mineral admixtures and applying them to actual engineering concrete is an effective measure to alleviate the current shortage of aggregate resources, reduce the impact on the ecological environment, and realize the resource utilization of tunnel slag.

[0003] Shotcrete is a key support material in tunnel construction. It has the characteristics of simple process, fast construction speed, short setting time and high early strength. Its main function is to bond with the surrounding rock, control the relaxation, deformation or deterioration of the surrounding rock, and prevent the surrounding rock from softening and becoming unstable due to contact with water. A large number of engineering practices have shown that the main problem of shotcrete at present is the high rebound rate, which not only causes quality defects due to the thin thickness of the shotcrete, but also wastes material resources and increases construction costs. From a material perspective, improving the cohesiveness of the concrete mixture, increasing the bonding strength between the concrete and the surrounding rock, and shortening the setting time of the concrete can enable the shotcrete to achieve a lower level of rebound rate. Invention patent CN202410148019.4 uses the early strength effect of nano calcium carbonate and the consumption of free water to prepare low-rebound shotcrete. Invention patent CN202110612128.3 uses emulsified asphalt to modify cement slurry to prepare low-rebound shotcrete. Invention patent CN202211183448.2 uses bioadhesive to improve the cohesion and stability of concrete to prepare low-rebound shotcrete. However, the preparation cost of the above method is high and the needs of green development are not taken into account.

[0004] At present, there is no reasonable technical solution to organically combine the high-quality utilization of tunnel slag with the preparation of low-rebound shotcrete.

[0005] Therefore, how to provide a thickening type rock-based mineral admixture and low-rebound slag shotcrete is a problem that technical personnel in this field urgently need to solve. Summary of the invention

[0006] In order to overcome the shortcomings and deficiencies in the prior art, the present invention provides a thickening type rock-based mineral admixture and concrete, which utilizes the good hydrophilicity of carbonate stone powder to prepare a highly active thickening type rock-based mineral admixture, improve the cohesiveness of concrete, and enhance the bonding force between shotcrete and the rock wall of the tunnel, thereby preparing low-rebound shotcrete. The present invention prepares the tunnel slag produced during tunnel excavation into homogenized admixtures and aggregates, and after being prepared into shotcrete with other components, all of them are used in tunnel construction, so that the tunnel slag reaches 100% utilization rate, and the green production concept of taking from the tunnel and using it in the tunnel is implemented, which has the advantages of green environmental protection, obvious economic benefits, and stable concrete quality.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A thickening rock-based mineral admixture comprises the following raw materials in parts by weight: 75-90 parts of a rock component, 10-20 parts of an activated component, and 2-5 parts of a modified component;

[0009] The rock component is ground carbonate cave slag, which is selected from one of limestone, marble and dolomite.

[0010] Preferably, the activating component is selected from one or more of silica fume, fly ash, slag powder, ultrafine slag powder and glass beads.

[0011] Preferably, the modified component is selected from one or more of cellulose, polyacrylic acid, bentonite, triethanolamine, polycarboxylic acid water reducer powder, and air entraining agent powder.

[0012] The beneficial effects of the above technical scheme are as follows: the present invention uses hydrophilic carbonate tunnel slag to prepare ground rock-based mineral admixture rock components, which has the effect of improving cohesion in fresh concrete slurry; the addition of activated components increases the active components of the rock-based mineral admixture, ensuring that it will not reduce the compressive strength of the concrete after replacing an appropriate amount of cement; the modified components further increase the thickening effect of the rock-based mineral admixture, improve the bonding strength between the shotcrete and the rock wall, and effectively reduce the rebound rate of the shotcrete.

[0013] Preferably, the thickening rock-based mineral admixture has a 45 μm sieve residue of no more than 20%, an activity index of no less than 75%, and a methylene blue value of no more than 1.0 g / kg.

[0014] The above-mentioned method for preparing a thickening rock-based mineral admixture comprises the following steps:

[0015] (1) Add the slag rock particles into the crusher and crush them into particles with a particle size of no more than 5 mm. The crushed particles are quantitatively fed into the ball mill in a continuous feeding manner. The discharge end of the ball mill is provided with a multi-layer screen. The ground particles enter the mixer from the grinder under the thrust of the airflow to form rock components;

[0016] (2) Continue to add the activated component and the modified component into the mixer and dry mix for 10 minutes to obtain a thickened rock-based mineral admixture.

[0017] The present invention also provides a low-rebound slag shotcrete, the raw materials of which include the above-mentioned thickening rock-based mineral admixture, ordinary Portland cement, homogeneous fully-graded slag aggregate, accelerator and water; the weight parts of the raw materials are: 350-550 parts of ordinary Portland cement, 50-150 parts of thickening rock-based mineral admixture, 1600-1850 parts of homogeneous fully-graded slag aggregate, 30-50 parts of accelerator and 165-195 parts of water.

[0018] Preferably, the raw material material of the homogeneous fully-graded slag aggregate is the same as the rock component of the thickening rock-based mineral admixture.

[0019] Preferably, the homogeneous fully-graded slag aggregate is composed of coarse and fine aggregates of 0-5mm, 5-10mm, and 10-20mm in a weight ratio of 50-55:12-18:28-38.

[0020] The beneficial effect of the above technical solution is: the present invention proposes a method for preparing homogeneous and fully graded tunnel slag aggregate, so that the mineral admixtures and aggregates inside the concrete are all from the same source of material, ensuring the good homogeneity and high stability of the concrete, while achieving 100% full utilization of tunnel slag, and practicing the green production concept of taking from the tunnel and using it in the tunnel.

[0021] The present invention also provides a method for preparing the above-mentioned low-rebound slag shotcrete, and the specific operation is: ordinary Portland cement, thickening rock-based mineral admixture, homogeneous fully-graded slag aggregate and water are mixed, and stirred continuously at a rate of 30r / min for 5 minutes to form uniform freshly mixed concrete, and then a wet spraying process is used within 45 minutes to spray the freshly mixed concrete and the accelerator simultaneously to form initial support on the tunnel rock wall.

[0022] It can be seen from the above technical solutions that, compared with the prior art, the present invention provides a thickening type rock-based mineral admixture and concrete, which has the following beneficial effects:

[0023] (1) The present invention makes efficient use of tunnel slag, which is green and environmentally friendly. The present invention processes the tunnel slag produced during tunnel excavation into stone, sand, and powder, and uses 100% of it as raw materials for shotcrete, returning the tunnel slag to tunnel construction, solving the contradiction between the difficulty in disposing of huge amounts of tunnel slag in engineering construction and the shortage of bulk material resources, and is very friendly to the ecological environment.

[0024] (2) The present invention has low production cost, which greatly reduces the project cost. The comprehensive production cost of the thickening rock-based mineral admixture prepared by using tunnel slag is significantly lower than the cost of mineral admixtures such as fly ash and slag powder. The cost of sand and gravel aggregate prepared by using tunnel slag is much lower than the cost of natural river sand, which greatly reduces the comprehensive cost of the prepared shotcrete, which has great advantages in alleviating the high cost of mountain projects.

[0025] (3) The sprayed concrete of the present invention has stable quality and good deformation coordination. The present invention uses tunnel slag of the same quality to prepare the same source of stone, sand and powder raw materials, so that the homogeneity and quality stability of the concrete can be well controlled. At the same time, the physical and chemical properties of the homogeneous fully graded aggregates are similar. When the sprayed concrete plays a supporting role in the tunnel, it can play a coordinated deformation role and reduce the risk of cracking of the concrete structure. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] A thickening type rock-based mineral admixture and low-rebound slag shotcrete thereof, the raw material mix ratio is as follows:

[0029] 1m 3 The raw materials contained in the shotcrete are as follows: 450 kg of ordinary Portland cement, 50 kg of thickening rock-based mineral admixture, 1629 kg of homogeneous fully graded slag aggregate, 40 kg of accelerator, and 187 kg of water.

[0030] The preparation method is implemented according to the following steps:

[0031] (1) limestone slag rock particles are added to a crusher to be crushed into particles with a particle size of no more than 5 mm. The crushed particles are quantitatively fed into a ball mill in a continuous feeding manner. A multi-layer screen is provided at the discharge end of the ball mill. The ground particles enter a mixer from the grinder under the thrust of airflow to form a rock component. The activated component and the modified component are then added to the mixer in a ratio of 85 parts of the rock component, 10 parts of the activated component, and 5 parts of the modified component. The mixture is dry-mixed for 10 minutes to form a thickening type rock-based mineral admixture;

[0032] (2) using tunnel slag of the same rock component material as the thickening rock-based mineral admixture to prepare homogeneous fully graded tunnel slag aggregate, wherein the fully graded tunnel slag aggregate is composed of 52 parts by weight of 0-5 mm aggregate, 14 parts by weight of 5-10 mm aggregate, and 34 parts by weight of 10-20 mm aggregate;

[0033] (3) Ordinary Portland cement, thickening rock-based mineral admixture, homogeneous fully graded tunnel slag aggregate, and water are mixed and stirred at a rate of 30 r / min for 5 min to make uniform fresh concrete. Then, the wet spraying process is used to spray the fresh concrete and the accelerator simultaneously within 45 min to form initial support for the tunnel rock wall.

[0034] Example 2

[0035] A thickening type rock-based mineral admixture and low-rebound slag shotcrete thereof, the raw material mix ratio is as follows:

[0036] 1m 3 The raw materials contained in the shotcrete are as follows: 400 kg of ordinary Portland cement, 100 kg of thickening rock-based mineral admixture, 1629 kg of homogeneous fully graded slag aggregate, 40 kg of accelerator, and 187 kg of water.

[0037] The preparation method is implemented according to the following steps:

[0038] (1) marble cave slag rock particles are added to a crusher to be crushed into particles with a particle size of no more than 5 mm. The crushed particles are quantitatively fed into a ball mill in a continuous feeding manner. A multi-layer screen is provided at the discharge end of the ball mill. The ground particles enter a mixer from the grinder under the thrust of airflow to form a rock component. The activated component and the modified component are then added to the mixer in a ratio of 85 parts of the rock component, 10 parts of the activated component, and 5 parts of the modified component. The components are dry mixed for 10 minutes to form a thickening type rock-based mineral admixture;

[0039] (2) using tunnel slag of the same rock component material as the thickening rock-based mineral admixture to prepare homogeneous fully graded tunnel slag aggregate, wherein the fully graded tunnel slag aggregate is composed of 52 parts by weight of 0-5 mm aggregate, 14 parts by weight of 5-10 mm aggregate, and 34 parts by weight of 10-20 mm aggregate;

[0040] (3) Ordinary Portland cement, thickening rock-based mineral admixture, homogeneous fully graded tunnel slag aggregate, and water are mixed and stirred at a rate of 30 r / min for 5 min to make uniform fresh concrete. Then, the wet spraying process is used to spray the fresh concrete and the accelerator simultaneously within 45 min to form initial support for the tunnel rock wall.

[0041] Example 3

[0042] A thickening type rock-based mineral admixture and low-rebound slag shotcrete thereof, the raw material mix ratio is as follows:

[0043] 1m 3 The raw materials contained in the shotcrete are as follows: 350 kg of ordinary Portland cement, 150 kg of thickening rock-based mineral admixture, 1629 kg of homogeneous fully graded slag aggregate, 40 kg of accelerator, and 187 kg of water.

[0044] The preparation method is implemented according to the following steps:

[0045] (1) Adding dolomite cave slag rock particles into a crusher to crush them into particles with a particle size of no more than 5 mm, the crushed particles are quantitatively fed into a ball mill in a continuous feeding manner, and a multi-layer screen is provided at the discharge end of the ball mill. The ground particles enter a mixer from the grinder under the thrust of airflow to form a rock component, and then add the activated component and the modified component into the mixer in a ratio of 85 parts of the rock component, 10 parts of the activated component, and 5 parts of the modified component, and dry mix for 10 minutes to form a thickening type rock-based mineral admixture;

[0046] (2) using tunnel slag of the same rock component material as the thickening rock-based mineral admixture to prepare homogeneous fully graded tunnel slag aggregate, wherein the fully graded tunnel slag aggregate is composed of 52 parts by weight of 0-5 mm aggregate, 14 parts by weight of 5-10 mm aggregate, and 34 parts by weight of 10-20 mm aggregate;

[0047] (3) Ordinary Portland cement, thickening rock-based mineral admixture, homogeneous fully graded tunnel slag aggregate, and water are mixed and stirred at a rate of 30 r / min for 5 min to make uniform fresh concrete. Then, the wet spraying process is used to spray the fresh concrete and the accelerator simultaneously within 45 min to form initial support for the tunnel rock wall.

[0048] Comparative Example 1

[0049] A shotcrete, the raw material mix ratio is as follows:

[0050] 1m 3 The raw materials contained in shotcrete are as follows: 400kg of ordinary Portland cement, 100kg of ordinary limestone powder, 1629kg of aggregate, 40kg of accelerator, and 187kg of water.

[0051] The preparation method is implemented as follows:

[0052] Ordinary Portland cement, ordinary limestone powder, aggregate and water are mixed and stirred at a rate of 30r / min for 5 minutes to make uniform fresh concrete. Then, the wet spraying process is used within 45 minutes to spray the fresh concrete and the accelerator at the same time to form initial support for the tunnel rock wall.

[0053] Table 1 is the test results of shotcrete of Examples 1-3 and Comparative Example 1, where the samples used for compressive strength were obtained from the core drilled on the tunnel support, and the test process was carried out in accordance with GB / T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete"; the bond strength with the surrounding rock was measured by directly pulling the drilled shotcrete-rock sample with a tensile machine; the rebound rate was obtained by dividing the difference between the designed amount of shotcrete used in the initial support of the tunnel and the actual amount by the actual amount. The comprehensive cost was calculated according to the average price of each raw material on the market.

[0054] Table 1 Shotcrete test results

[0055]

[0056] It can be seen from the above table that the compressive strength and bonding strength of the shotcrete prepared in Examples 1-3 are higher than those in Comparative Example 1, and the rebound rate and comprehensive cost are lower than those in Comparative Example 1, indicating that the shotcrete prepared with rock-based mineral admixtures has good performance and can reduce the cost of the project.

[0057] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the scheme disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0058] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A thickening rock-based mineral admixture, characterized in that: The raw materials include the following parts by weight: 75-90 parts of rock component, 10-20 parts of activation component, and 2-5 parts of modification component; The rock component is ground carbonate cave slag, which is selected from one of limestone, marble and dolomite.

2. A thickening rock-based mineral admixture according to claim 1, characterized in that: The activating component is selected from one or more of silica fume, fly ash, slag powder, ultrafine slag powder and glass microbeads.

3. A thickening rock-based mineral admixture according to claim 1, characterized in that: The modified component is selected from one or more of cellulose, polyacrylic acid, bentonite, triethanolamine, polycarboxylic acid water reducer powder, and air entraining agent powder.

4. A thickening rock-based mineral admixture according to claim 1, characterized in that: The thickening rock-based mineral admixture has a 45 μm sieve residue of no more than 20%, an activity index of no less than 75%, and a methylene blue value of no more than 1.0 g / kg.

5. The method for preparing a thickening rock-based mineral admixture according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Add the slag rock particles into the crusher and crush them into particles with a particle size of no more than 5 mm. The crushed particles are quantitatively fed into the ball mill in a continuous feeding manner. The discharge end of the ball mill is provided with a multi-layer screen. The ground particles enter the mixer from the grinder under the thrust of the airflow to form rock components; (2) Continue to add the activated component and the modified component into the mixer and dry mix for 10 minutes to obtain a thickened rock-based mineral admixture.

6. A low-rebound slag shotcrete, characterized in that: The raw materials include the thickening rock-based mineral admixture described in any one of claims 1 to 4, ordinary Portland cement, homogeneous fully-graded slag aggregate, accelerator and water; the weight parts of the above raw materials are: 350-550 parts of ordinary Portland cement, 50-150 parts of thickening rock-based mineral admixture, 1600-1850 parts of homogeneous fully-graded slag aggregate, 30-50 parts of accelerator and 165-195 parts of water.

7. The low-rebound slag shotcrete according to claim 6, characterized in that: The raw material material of the homogeneous fully-graded slag aggregate is the same as the rock component of the thickening rock-based mineral admixture.

8. The low-rebound slag shotcrete according to claim 6, characterized in that: The homogeneous fully graded slag aggregate is prepared by mixing coarse and fine aggregates of 0-5mm, 5-10mm and 10-20mm in a weight ratio of 50-55:12-18:28-38.

9. The method for preparing low-rebound cavity slag shotcrete according to claim 6, characterized in that: The specific operation is: ordinary Portland cement, thickening rock-based mineral admixture, homogeneous fully graded tunnel slag aggregate and water are mixed, and stirred continuously at a rate of 30r / min for 5 minutes to make uniform freshly mixed concrete. Then, the wet spraying process is used within 45 minutes to spray the freshly mixed concrete and the accelerator at the same time to form initial support on the tunnel rock wall.

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