Seaside saline soil solidifying agent and its preparation method and application

Abstract

The present invention relates to the technical field of building materials, and in particular to a coastal saline soil solidifier, a preparation method and an application thereof. The present invention adopts air-cooled high-carbon ferrochrome slag powder as the main raw material, adds mineral powder and fly ash, and adds Bayer process red mud and sulfide sintering process red mud to prepare a coastal saline soil solidifier with good mechanical properties, high water resistance, low energy consumption and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, in particular to a coastal saline soil curing agent and a preparation method and application thereof. Background Art

[0002] With the continuous expansion of infrastructure construction, soil solidification technology is increasingly being used in foundation reinforcement and road subbase treatment. Soil solidifiers mostly use inorganic building materials such as cement and lime. However, studies have shown that for saline soils in coastal and inland areas, traditional solidifiers are difficult to effectively solidify the chlorides and sulfates therein, and there are engineering safety hazards due to salt swelling, corrosion, and dissolution.

[0003] The inventors previously studied saline soil using ferrochrome slag slag, slag, gypsum, and lime as curing agents, and effectively solidified aluminum-containing saline soil. This study used a large amount of high-quality raw materials such as gypsum and lime, and did not study the air-cooled high-carbon ferrochrome slag dry slag with lower activity. The resource utilization of industrial waste residue is conducive to the realization of dual carbon goals, and there is still a research gap in further improving the high-value resource utilization of industrial waste residue in saline soil curing and improving the curing strength of saline soil. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a coastal saline soil solidifier. Specifically, the present invention uses air-cooled high-carbon ferrochrome slag powder as the main raw material, adds mineral powder and fly ash, and adds Bayer process red mud and sulfide sintering process red mud to prepare a coastal saline soil solidifier with good mechanical properties, high water resistance, low energy consumption and low cost.

[0005] Specifically, the coastal saline soil solidifier of the present invention is composed of the following raw materials in parts by weight: 45-55 parts of air-cooled high-carbon ferrochrome slag powder, 5-8 parts of mineral powder, 3-5 parts of fly ash, 25-30 parts of Bayer process red mud, and 15-20 parts of sulfide sintering process red mud.

[0006] Preferably, the air-cooled high-carbon ferrochrome slag powder is obtained by grinding air-cooled high-carbon ferrochrome slag.

[0007] Preferably, the grinding is carried out by ultrafine grinding for 8-15 minutes, and the specific surface area of ​​the air-cooled high carbon ferrochrome slag powder is .

[0008] Air-cooled high-carbon ferrochrome slag is obtained by air-cooling and crushing slag, also known as dry slag. The inventor's research shows that the chemical composition of dry slag is similar to that of water-quenched slag, but its activity is lower than that of water-quenched slag, and its reuse is difficult. Red mud is a by-product of the aluminum smelting industry. It is divided into Bayer process red mud and sintering process red mud according to different processes. The main chemical components of both are 、 The content of active CaO in sintered red mud is higher than that in Bayer red mud, and the alkalinity is higher.

[0009] The present invention adopts air-cooled high-carbon ferrochrome slag powder as the main raw material, adds a small amount of fly ash and mineral powder as supplements of active siliceous and aluminous raw materials, and selects the addition of Bayer red mud and sulfide sintering red mud as activators and active substances after a large number of tests. The Bayer red mud provides active CaO to increase the alkalinity, and the active CaO in the sulfide sintering red mud absorbs sulfur dioxide in hot flue gas and is oxidized to form gypsum. The active siliceous and aluminous substances in the Bayer red mud and the sulfide sintering red mud can also serve as hydration active substances to participate in the hydration and solidification reaction.

[0010] The present invention has found that red mud from the sulfide sintering process has high activity and stable performance. It and Bayer process red mud have a good stimulating effect on air-cooled high-carbon ferrochrome slag powder. The hydration products can effectively solidify chloride ions and sulfate ions in saline soil, generating stable Friedel salts and Kuzel salts. The salts are closely intertwined with hydration products such as ettringite AFt, CSH and CAH to form a good saline soil solidification body. The stimulating effect of red mud from the sulfide sintering process is better than that of directly using gypsum. The addition of gypsum will not cause excessively rapid generation of AFt, resulting in volume expansion and damage, and the solidified soil has better stability.

[0011] Preferably, the mineral powder is at least one of S95 grade and S105 grade.

[0012] Preferably, the fly ash is at least one of primary fly ash and secondary fly ash.

[0013] Preferably, the chemical composition of the Bayer process red mud includes 、 、 、 、 , impurity residue.

[0014] Preferably, the sulfurized sintered red mud is obtained by mixing sintered red mud and water in a mass ratio of 1:(0.3-0.5) to moisten the mixture, sulfurizing the mixture with sulfur-containing flue gas at an ambient pressure of 0.1-0.5 MPa, and then drying and grinding the mixture.

[0015] Preferably, the chemical composition of the sintering red mud includes 、 、 、 、 , impurity residue.

[0016] Preferably, the particle size of the Bayer process red mud and the sulfide sintering process red mud is ≤75 μm.

[0017] The present invention also relates to a method for preparing the above-mentioned coastal saline soil solidifying agent, which specifically comprises the following steps:

[0018] 1) Weigh each raw material by weight,

[0019] 2) Mix all the raw materials evenly.

[0020] The present invention also relates to the application of the above-mentioned seashore saline soil solidifying agent in the solidification of seashore saline soil.

[0021] Preferably, the amount of the curing agent added is 10-20% of the dry soil mass of the coastal saline soil.

[0022] The present invention has the following technical advantages:

[0023] 1. The present invention uses air-cooled high-carbon ferrochrome slag powder as the main raw material to achieve high-value utilization of dry slag.

[0024] 2. The present invention uses all solid waste raw materials to prepare the curing agent, which is low in price and realizes the high-value resource utilization of industrial solid waste.

[0025] 3. The curing agent of the present invention has a good curing effect on coastal saline soil, achieving effective curing of chloride ions and sulfate ions in the saline soil, and the cured soil has high mechanical strength and good water resistance. DETAILED DESCRIPTION

[0026] In order to characterize the technical effect of the present invention, a curing agent was prepared and solidified soil was prepared for performance testing. During the test, the saline soil was prepared from the saline soil of Lianyungang in the paper "Study on the reaction mechanism of ferrochrome slag-slag-based polymer solidification of chlorine-salted soil based on chloride constraint". The air-cooled high-carbon ferrochrome slag powder was ground by ultrafine grinding machine for 10 minutes, and the specific surface area was 2.3777m / s. The mineral powder is S95 grade mineral powder, the fly ash is secondary fly ash, the amount of curing agent added is 15% of the dry weight of saline soil, and the water consumption is the optimal moisture content of 24.58%.

[0027] Example 1

[0028] The curing agent is composed of the following raw materials in parts by weight: 50 parts of air-cooled high-carbon ferrochrome slag powder, 5 parts of mineral powder, 5 parts of fly ash, 26 parts of Bayer process red mud, and 20 parts of sulfide sintering process red mud.

[0029] After testing, the compressive strength of the solidified soil after 28 days of standard curing is 7.2MPa, and the compressive strength after 27 days of standard curing + 1 day of seawater immersion curing is 7.1MPa.

[0030] Example 2

[0031] The curing agent is composed of the following raw materials in parts by weight: 52 parts of air-cooled high-carbon ferrochrome slag powder, 6 parts of mineral powder, 3 parts of fly ash, 25 parts of Bayer red mud, and 19 parts of sulfide sintering red mud.

[0032] After testing, the compressive strength of the solidified soil after 28 days of standard curing is 7.5MPa, and the compressive strength after 27 days of standard curing + 1 day of seawater immersion curing is 7.2MPa.

[0033] Comparative Example 1

[0034] The curing agent is composed of the following raw materials in parts by weight: 60 parts of air-cooled high-carbon ferrochrome slag powder, 5 parts of mineral powder, 5 parts of fly ash, and 36 parts of Bayer red mud.

[0035] After testing, the compressive strength of the solidified soil after 28 days of standard curing is 3.6 MPa, and the compressive strength after 27 days of standard curing + 1 day of seawater immersion curing is 2.9 MPa.

[0036] Comparative Example 2

[0037] The curing agent is composed of the following raw materials in parts by weight: 60 parts of air-cooled high-carbon ferrochrome slag powder, 5 parts of mineral powder, 5 parts of fly ash, and 36 parts of sulfide sintering red mud.

[0038] After testing, the compressive strength of the solidified soil after 28 days of standard curing is 2.0 MPa, and the compressive strength after 27 days of standard curing + 1 day of seawater immersion curing is 1.4 MPa.

[0039] Comparative Example 3

[0040] The curing agent is composed of the following raw materials in parts by weight: 50 parts of air-cooled high-carbon ferrochrome slag powder, 5 parts of mineral powder, 5 parts of fly ash, 26 parts of Bayer red mud, and 20 parts of sintered red mud.

[0041] After testing, the compressive strength of the solidified soil after 28 days of standard curing is 4.6 MPa, and the compressive strength after 27 days of standard curing + 1 day of seawater immersion curing is 4.0 MPa.

[0042] Comparative Example 4

[0043] The curing agent is composed of the following raw materials in parts by weight: 50 parts of air-cooled high-carbon ferrochrome slag powder, 25 parts of mineral powder, 5 parts of fly ash, and 26 parts of desulfurized gypsum.

[0044] After testing, the compressive strength of the solidified soil after 28 days of standard curing is 2.7 MPa, and the compressive strength after 27 days of standard curing + 1 day of seawater immersion curing is 1.9 MPa.

[0045] Comparative Example 5

[0046] The curing agent is composed of the following raw materials in parts by weight: 50 parts of air-cooled high-carbon ferrochrome slag powder, 5 parts of mineral powder, 15 parts of fly ash, 26 parts of carbide slag, and 10 parts of desulfurized gypsum.

[0047] After testing, the compressive strength of the solidified soil after 28 days of standard curing is 2.5MPa, and the compressive strength after 27 days of standard curing + 1 day of seawater immersion curing is 1.5MPa.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coastal saline soil solidifier, characterized in that: Composed of the following parts by weight of raw materials: air-cooled high carbon ferrochrome slag powder 45-55 parts, 5-8 parts of slag, 3-5 parts of fly ash, 25-30 parts of Bayer red mud, 15-20 parts of sulfide sintering red mud; The air-cooled high-carbon ferrochrome slag powder is obtained by grinding air-cooled high-carbon ferrochrome slag; The chemical composition of the Bayer process red mud includes 、 、 、 、 , impurity residue; The sulfurized sintered red mud is obtained by mixing sintered red mud and water in a mass ratio of 1:(0.3-0.5) to moisten the mixture, sulfurizing the mixture with sulfur-containing flue gas at an ambient pressure of 0.1-0.5 MPa, and then drying and grinding the mixture to obtain the mixture.

2. The seashore saline soil solidifying agent according to claim 1, characterized in that: The grinding is carried out by using an ultrafine grinding mill for 8-15 minutes.

3. The seashore saline soil solidifying agent according to claim 1, characterized in that: The specific surface area of ​​the air-cooled high carbon ferrochrome slag powder .

4. The seashore saline soil solidifying agent according to claim 1, characterized in that: The mineral powder is at least one of S95 grade and S105 grade.

5. The coastal saline soil solidifying agent according to claim 1, characterized in that: The fly ash is at least one of primary fly ash and secondary fly ash.

6. The coastal saline soil solidifying agent according to claim 1, characterized in that: The chemical composition of the sintering red mud includes 、 、 、 、 , impurity residue.

7. The method for preparing the seashore saline soil solidifying agent according to any one of claims 1 to 6, characterized in that: The steps include: 1) Weigh each raw material by weight, 2) Mix all the raw materials evenly.

8. Use of the seaside saline soil solidifying agent according to any one of claims 1 to 7 in the solidification of seaside saline soil.

9. The use according to claim 8, characterized in that The amount of the curing agent added is 10-20% of the dry soil mass of the coastal saline soil.