Barium-containing sulphoaluminate soft soil curing agent and preparation method thereof

Abstract

The invention discloses a barium-containing sulphoaluminate soft soil curing agent and a preparation method thereof. The soft soil curing agent is prepared from the following materials in parts by mass: 65-75 parts of barium-containing sulphoaluminate, 10-15 parts of C-S-H gel, 20-25 parts of gypsum powder, 5-10 parts of an alkaline activator, 5-10 parts of an activator and 5-10 parts of a retarder. The barium-containing sulphoaluminate reacts with free water in soil, generated needle-shaped ettringite minerals can bond soil particles, meanwhile, C-S-H gel can generate a synergistic effect with ettringite, the C-S-H gel regulates and controls growth of ettringite crystals, a framework structure is formed to support the whole soil body, the solidification speed of soft soil is greatly increased, and the strength of solidified soil is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of soft soil curing agents, in particular to a barium sulphoaluminate-containing soft soil curing agent and a preparation method thereof. Background Art

[0002] Soft soil refers to a type of soil with low bearing capacity, large porosity, high water content and high compression. Strengthening soft soil foundation has become one of the hot topics in engineering construction and maintenance. There are many methods for strengthening soft soil, such as compaction reinforcement, heat treatment reinforcement and chemical reinforcement. Among them, curing agent reinforcement of soft soil has become the most widely used soft soil reinforcement method due to its low cost and relatively simple construction.

[0003] Soft soil solidifier refers to a material that can directly bond soil particles at room temperature, or can react with clay minerals to form cementitious substances, thereby improving the physical properties of the soil. Soft soil solidifiers can be divided into calcium-based solidifiers (cement, lime, fly ash, slag, etc.) and non-calcium-based solidifiers (ionic solidifiers, enzyme solidifiers, polymer solidifiers, etc.) according to their main components.

[0004] However, the main raw materials of most soft soil solidifying agents in currently disclosed patents and published literature are to use strong alkaline substances such as water glass and sodium hydroxide to undergo physical and chemical reactions such as depolymerization with SiO2 and Al2O3 in slag and fly ash to generate substances such as calcium aluminate to produce cementation, thereby condensing soil particles into an integral, solid, stable and durable plate structure, but the agglomerates produced by the cementation have a low solidification speed in the soil and a low strength of the solidified soil. Summary of the invention

[0005] The present invention provides a barium sulphoaluminate soft soil solidifying agent and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A barium sulphoaluminate soft soil curing agent is prepared from the following materials in parts by mass: 65-75 parts of barium sulphoaluminate, 10-15 parts of CSH gel, 20-25 parts of gypsum powder, 5-10 parts of alkaline activator, 5-10 parts of activator and 5-10 parts of retarder.

[0008] As a further improvement of the technical solution: the soft soil curing agent is made of the following materials in parts by mass: 65 parts of barium sulphoaluminate, 10 parts of CSH gel, 20 parts of gypsum powder, 5 parts of alkaline activator, 5 parts of activator and 5 parts of retarder.

[0009] As a further improvement of the technical solution: the soft soil curing agent is made of the following materials in parts by mass: 70 parts of barium sulphoaluminate, 13 parts of CSH gel, 23 parts of gypsum powder, 8 parts of alkaline activator, 8 parts of activator and 8 parts of retarder.

[0010] As a further improvement of the technical solution: the soft soil curing agent is made of the following materials in parts by mass: 75 parts of barium sulphoaluminate, 15 parts of CSH gel, 25 parts of gypsum powder, 10 parts of alkaline activator, 10 parts of activator and 10 parts of retarder.

[0011] As a further improvement of the technical solution: the alkaline activator is a composite mixed material of commercially available Conch brand 425 grade cement and one or more of Na2CO3, NaOH, Na2SO4, K2NO2, NaF, and K2CO3.

[0012] As a further improvement of the technical solution: the activator is one or more composite materials of triethanolamine, sulfite pulp waste liquid, sodium lignosulfonate, and calcium lignosulfonate.

[0013] As a further improvement of the technical solution: the retarder is one or more composite materials of tartaric acid, citric acid, salicylic acid, methyl cellulose, and sodium carboxymethyl cellulose.

[0014] As a further improvement of the technical solution: the gypsum powder is made by crushing and ball-milling industrial gypsum, and its main mineral component is dihydrate gypsum, and the content of dihydrate gypsum accounts for 90-95wt%.

[0015] The present invention also provides a method for preparing a barium sulphoaluminate soft soil curing agent, comprising the following steps:

[0016] The first step is to crush and grind the barium-containing waste slag and sulphoaluminate cement clinker, mix them evenly in a ratio of 1:1, and then put the mixed materials into a high-temperature furnace for calcination. After the calcination is completed, the materials are taken out and naturally cooled to obtain barium-containing sulphoaluminate;

[0017] In the second step, the barium sulphoaluminate prepared in the first step is put into a mixer in proportion with CSH gel, gypsum powder, alkaline activator, activator and retarder and mixed evenly to obtain a barium sulphoaluminate soft soil curing agent.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention reacts barium sulphoaluminate with free water in the soil to generate needle-shaped ettringite minerals that can cement soil particles. At the same time, CSH gel can produce a synergistic effect with ettringite. CSH gel regulates the growth of ettringite crystals to form a skeleton structure to support the entire soil body, greatly improving the solidification speed of soft soil and the strength of solidified soil.

[0020] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. The specific implementation of the present invention is given in detail by the following embodiments and their accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0022] Figure 1 This is a schematic diagram of a preparation method of a barium sulphoaluminate soft soil solidifying agent proposed by the present invention. DETAILED DESCRIPTION

[0023] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention. The present invention is described in more detail by way of example with reference to the accompanying drawings in the following paragraphs. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0024] Embodiment 1

[0025] A barium sulphoaluminate soft soil curing agent is prepared from the following materials in parts by mass: 65 parts of barium sulphoaluminate, 10 parts of CSH gel, 20 parts of gypsum powder, 5 parts of alkaline activator, 5 parts of activator and 5 parts of retarder.

[0026] The alkaline activator is a composite material of commercially available Conch brand 425 grade cement and one or more of Na2CO3, NaOH, Na2SO4, K2NO2, NaF, and K2CO3;

[0027] The activator is one or more composite materials of triethanolamine, sulfite pulp waste liquor, sodium lignosulfonate, and calcium lignosulfonate;

[0028] The retarder is one or more composite materials of tartaric acid, citric acid, salicylic acid, methyl cellulose, and sodium carboxymethyl cellulose;

[0029] Gypsum powder is made by crushing and ball-milling industrial gypsum. Its main mineral component is dihydrate gypsum, which accounts for 90-95wt%;

[0030] The preparation method of the barium sulphoaluminate soft soil curing agent comprises the following steps:

[0031] The first step is to crush and grind the barium-containing waste slag and sulphoaluminate cement clinker, mix them evenly in a ratio of 1:1, and then put the mixed materials into a high-temperature furnace for calcination. After the calcination is completed, the materials are taken out and naturally cooled to obtain barium-containing sulphoaluminate;

[0032] In the second step, the barium sulphoaluminate prepared in the first step is put into a mixer in proportion with CSH gel, gypsum powder, alkaline activator, activator and retarder and mixed evenly to obtain a barium sulphoaluminate soft soil curing agent.

[0033] Embodiment 2

[0034] A barium sulphoaluminate soft soil curing agent is prepared from the following materials in parts by mass: 70 parts of barium sulphoaluminate, 13 parts of CSH gel, 23 parts of gypsum powder, 8 parts of alkaline activator, 8 parts of activator and 8 parts of retarder.

[0035] Embodiment 3

[0036] A barium sulphoaluminate soft soil curing agent is prepared from the following materials in parts by mass: 75 parts of barium sulphoaluminate, 15 parts of CSH gel, 25 parts of gypsum powder, 10 parts of alkaline activator, 10 parts of activator and 10 parts of retarder.

[0037] Comparative Example 1

[0038] The soft soil solidifying agent is made of the following materials in parts by mass: 65 parts of barium sulphoaluminate, 20 parts of gypsum powder, 5 parts of alkaline activator, 5 parts of activator and 5 parts of retarder.

[0039] The preparation method of the soft soil curing agent comprises the following steps:

[0040] The barium sulphoaluminate, gypsum powder, alkaline activator, activator and retarder are put into a mixer in proportion and mixed evenly to obtain the barium sulphoaluminate soft soil solidifying agent.

[0041] Comparative Example 2

[0042] The soft soil solidifying agent is made of the following materials in parts by mass: 70 parts of barium sulphoaluminate, 23 parts of gypsum powder, 8 parts of alkaline activator, 8 parts of activator and 8 parts of retarder.

[0043] The preparation method of the soft soil curing agent comprises the following steps:

[0044] The barium sulphoaluminate, gypsum powder, alkaline activator, activator and retarder are put into a mixer in proportion and mixed evenly to obtain the barium sulphoaluminate soft soil solidifying agent.

[0045] Comparative Example 3

[0046] The soft soil solidifying agent is made of the following materials in parts by mass: 75 parts of barium sulphoaluminate, 25 parts of gypsum powder, 10 parts of alkaline activator, 10 parts of activator and 10 parts of retarder.

[0047] The preparation method of the soft soil curing agent comprises the following steps:

[0048] The barium sulphoaluminate, gypsum powder, alkaline activator, activator and retarder are put into a mixer in proportion and mixed evenly to obtain the barium sulphoaluminate soft soil solidifying agent.

[0049] The soft soil curing agents prepared in the above Examples 1, 2, 3 and Comparative Examples 1, 2, 3 were tested:

[0050] The soft soil to be reinforced was taken from fine-grained saturated organic soil in Chengdu. The soil was dried at 110°C for 24 hours in advance and crushed with a rubber hammer until all of it passed through a 3mm round hole sieve. 20wt% of the curing agent prepared in Examples 1, 2, 3 and Comparative Examples 1, 2, 3 was added to the dried soil, and after stirring evenly, distilled water was added at a moisture content of 60%. After stirring for 2 minutes, the slurry was poured into a 40×40×160mm cement mortar test mold and vibrated to form. The cured soil was sealed together with the mold and cured at 20°C for 1 day and 3 days. After demolding, the unconfined compressive strength of the cured soil was measured. The materials and strengths of Examples 1, 2, 3 and Comparative Examples 1, 2, 3 are shown in Table 1 below.

[0051] Table 1 Unconfined compressive strength of yellow clay reinforced with curing agent and cement

[0052] 1 day unconfined compressive strength / KPa 3-day unconfined compressive strength / KPa Embodiment 1 853.82 878.89 Embodiment 2 863.53 881.23 Embodiment 3 852.76 861.72 Comparative Example 1 535.34 539.79 Comparative Example 2 545.11 549.32 Comparative Example 3 536.24 541.19

[0053] The curing agent proposed in the present invention utilizes the hydration reaction of barium sulfoaluminate minerals, and its curing mechanism is as follows: the soft soil curing agent is added to saturated soft soil, the barium sulfoaluminate immediately reacts with the free water in the soil, and a large amount of ettringite is generated in the liquid phase filled with gypsum. The generated needle-shaped ettringite minerals can cement soil particles, and at the same time, CSH gel can produce a synergistic effect with ettringite. The CSH gel regulates the growth of ettringite crystals to form a skeleton structure to support the entire soil body, thereby greatly improving the curing speed of the soft soil and the strength of the cured soil.

[0054] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A barium sulphoaluminate soft soil solidifying agent, characterized in that: The soft soil curing agent is made of the following materials in parts by mass: 65-75 parts of barium sulphoaluminate, 10-15 parts of CSH gel, 20-25 parts of gypsum powder, 5-10 parts of alkaline activator, 5-10 parts of activator and 5-10 parts of retarder.

2. The barium sulphoaluminate soft soil solidifying agent according to claim 1, characterized in that: The soft soil curing agent is made of the following materials in parts by mass: 65 parts of barium sulphoaluminate, 10 parts of CSH gel, 20 parts of gypsum powder, 5 parts of alkaline activator, 5 parts of activator and 5 parts of retarder.

3. The barium sulphoaluminate soft soil solidifying agent according to claim 1, characterized in that: The soft soil curing agent is made of the following materials in parts by mass: 70 parts of barium sulphoaluminate, 13 parts of CSH gel, 23 parts of gypsum powder, 8 parts of alkaline activator, 8 parts of activator and 8 parts of retarder.

4. The barium sulphoaluminate soft soil solidifying agent according to claim 1, characterized in that: The soft soil curing agent is made of the following materials in parts by mass: 75 parts of barium sulphoaluminate, 15 parts of CSH gel, 25 parts of gypsum powder, 10 parts of alkaline activator, 10 parts of activator and 10 parts of retarder.

5. The barium sulphoaluminate soft soil solidifying agent according to claim 1, characterized in that: The alkaline activator is a composite mixed material of commercially available Conch brand 425 grade cement and one or more of Na2CO3, NaOH, Na2SO4, K2NO2, NaF, and K2CO3.

6. The barium sulphoaluminate soft soil solidifying agent according to claim 1, characterized in that: The activator is one or more composite materials of triethanolamine, sulfite pulp waste liquor, sodium lignosulfonate and calcium lignosulfonate.

7. The barium sulphoaluminate soft soil solidifying agent according to claim 1, characterized in that: The retarder is one or more composite materials of tartaric acid, citric acid, salicylic acid, methyl cellulose and sodium carboxymethyl cellulose.

8. The barium sulphoaluminate soft soil solidifying agent according to claim 1, characterized in that: The gypsum powder is made by crushing and ball-milling industrial gypsum, and its main mineral component is dihydrate gypsum, and the content of dihydrate gypsum accounts for 90-95wt%.

9. The method for preparing the barium sulphoaluminate soft soil curing agent according to any one of claims 1 to 8, characterized in that: The following steps are involved: The first step is to crush and grind the barium-containing waste slag and sulphoaluminate cement clinker, mix them evenly in a ratio of 1:1, and then put the mixed materials into a high-temperature furnace for calcination. After the calcination is completed, the materials are taken out and naturally cooled to obtain barium-containing sulphoaluminate; In the second step, the barium sulphoaluminate prepared in the first step is put into a mixer in proportion with CSH gel, gypsum powder, alkaline activator, activator and retarder and mixed evenly to obtain a barium sulphoaluminate soft soil curing agent.

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