Geopolymer-based curing agent, preparation method and curing material

Abstract

The invention relates to the technical field of curing agents, in particular to a geopolymer-based curing agent, a preparation method and a curing material. The invention provides a geopolymer-based curing agent. The geopolymer-based curing agent comprises the following raw materials in percentage by weight: 25%-45% of aluminosilicate solid waste, 10%-30% of fly ash, 10%-30% of calcium-based solid waste, 5%-15% of a mineral regulator, 0.05%-0.1% of a plasticizer and 0.005%-0.01% of a surface modifier, wherein the mineral regulator is selected from at least one of bentonite and a calcium sulphoaluminate expanding agent. The geopolymer curing agent completely takes the geopolymer as the raw material, the neat paste fluidity of the curing agent meets the requirement, the slump of an obtained concrete mixture and the shrinkage rate of a curing material after the mixture is solidified can meet the related standard requirements, and the geopolymer curing agent is superior to a commercially available soft soil curing agent taking cement and calcium sulfate as the raw materials; and the method has important significance on environmental protection and sustainable development.

Description

Technical Field

[0001] The invention relates to the technical field of curing agents, and in particular to a geopolymer-based curing agent, a preparation method and a curing material. Background Art

[0002] Soil solidifier is a new type of soil solidification material. The construction industry uses mostly inorganic powders made of cement, fly ash, lime, desulfurized gypsum, etc. as the main raw materials, supplemented by admixtures. In recent years, with the implementation of the "dual carbon" development strategy, low carbonization has become the main theme of today's construction industry, which means a reduction in the use of cement, which is replaced by solid waste-based environmentally friendly materials. With the rapid development of my country's rail transit industry, for example, a large amount of shield engineering slag will be generated in subway construction. Due to its poor performance, it cannot be directly used in engineering construction. It is often necessary to add soil solidifiers to make it meet the application requirements. The preparation cost of commercially available soil solidifiers is currently high, which makes it impossible to timely and massively dispose of subway engineering slag, causing the accumulation of subway engineering slag to occupy a large amount of land, resulting in site shortages and environmental problems.

[0003] The curing principle of geopolymer (referred to as geopolymer) based soil curing agent is mainly to form a three-dimensional mesh gel structure composed of silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron. Compared with traditional soil curing agent, geopolymer based soil curing agent uses industrial solid waste as the main active raw material, and the activator component is mainly alkali solid waste and inorganic salt solid waste, which avoids the use of cement-based materials obtained by high-temperature calcination treatment, and conforms to the trend of low carbonization and cost reduction. However, geopolymer based soil curing agent still has problems such as large shrinkage and limited construction time. In this regard, the geopolymer-based curing agent in the patent with application number 202310244605.4 uses water glass as an alkali activator and polyacrylonitrile fiber as a toughening agent to resist shrinkage cracking. Although this method can solve the problems of large shrinkage and limited construction time of geopolymer-based soil curing agents to a certain extent, it is not convenient for actual construction operation and storage, and the plastic viscosity of the silt soft soil used is greater than that of general materials. The use of water glass and fiber will cause a significant increase in the viscosity of the cementitious material slurry and a serious decrease in workability. The application limitations are large, making it impossible to carry out pumping construction in engineering scenarios such as underground filling or subway tunnels. In addition, the curing agent dosage in this method is relatively high, resulting in increased costs. Therefore, how to use geopolymer-based soil curing agents to improve strength while ensuring that their shrinkage is controllable, workability is good, construction is simple and cost is low is an urgent problem to be solved in the preparation of geopolymer-based soil curing agents. Summary of the invention

[0004] In view of this, the present invention provides a geopolymer-based curing agent, a preparation method and a curing material. The geopolymer-based curing agent does not contain cement and has a simple preparation method. The curing material prepared by the geopolymer-based curing agent has good shrinkage controllability and workability while meeting work requirements in strength, thereby significantly reducing construction difficulty and improving work efficiency.

[0005] In order to solve the above technical problems, the present invention provides a geopolymer-based curing agent, wherein the raw material composition of the geopolymer-based curing agent comprises, by weight ratio: 25% to 45% of aluminosilicate solid waste, 10% to 30% of fly ash, 10% to 30% of calcium-based solid waste, 5% to 15% of mineral regulator, 0.05% to 0.1% of plasticizer, and 0.005% to 0.01% of surface modifier;

[0006] Wherein, the mineral regulator is selected from at least one of bentonite and calcium sulphoaluminate type expansion agent.

[0007] The geopolymer-based curing agent provided by the present invention has a raw material in which aluminosilicate solid waste reacts with calcium-based solid waste to form a geopolymer-based gelling material system, which serves as the strength source of the curing agent; the addition of a mineral regulator can improve the shrinkage and cracking problem of the cured material obtained by using the geopolymer-based curing agent, and ensure the curing performance; the addition of a plasticizer is intended to improve the workability of the geopolymer-based curing agent and the controllability of the setting, bringing convenience to on-site construction applications; the use of a surface modifier can improve the liquid surface tension of the curing agent when adding water for on-site construction, reduce the cohesion between the liquid and solid phases, and thus improve the pumpability of the cured material.

[0008] In combination with the first aspect, the aluminosilicate solid waste is silicate solid waste or aluminate solid waste.

[0009] Preferably, the aluminosilicate solid waste may be slag powder and / or yellow phosphorus slag powder.

[0010] Further preferably, the slag powder or yellow phosphorus slag powder reaches the performance standard of mineral powder S95 grade. This grade of slag powder or yellow phosphorus slag powder has high reaction activity and is easier to react with the alkali in the geopolymer.

[0011] In combination with the first aspect, the specific surface area of ​​the aluminosilicate solid waste is ≥350m 2 / kg, using a specific surface area ≥350m 2 / kg of aluminosilicate solid waste can better stimulate its volcanic ash activity.

[0012] In combination with the first aspect, the calcium-based solid waste is selected from at least one of desulfurized gypsum, phosphogypsum, industrial dihydrate gypsum and industrial hemihydrate gypsum, and carbide slag. The main components of the calcium-based solid waste used in the present invention are calcium sulfate and calcium oxide (which forms calcium hydroxide when in contact with water to provide an alkaline environment), wherein the content of calcium oxide in the carbide slag is greater than 90%.

[0013] In combination with the first aspect, the particle size of the calcium-based solid waste does not exceed 48 μm. The excessively large particle size of the calcium-based solid waste makes it difficult to dissolve and has poor reactivity.

[0014] In combination with the first aspect, the plasticizer is selected from at least one of sodium lignin sulfonate, catechol and triethanolamine.

[0015] In combination with the first aspect, the surface modifier is selected from at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, hydroxypropyl methylcellulose and polyacrylamide.

[0016] The second aspect of the present invention provides a method for preparing the above-mentioned geopolymer-based curing agent, the steps comprising: adding the aluminosilicate solid waste, fly ash, calcium-based solid waste, mineral regulator, plasticizer and surface modifier into a mixer according to the designed proportion and mixing them evenly to obtain the geopolymer-based curing agent.

[0017] The preparation method of the geopolymer-based curing agent provided by the present invention only requires uniform mixing of various raw materials to obtain a powdered geopolymer-based curing agent, and the preparation steps are simple and the construction operation is convenient.

[0018] Preferably, the water content of the obtained geopolymer-based curing agent is controlled at 1% or less, and the fineness is controlled as follows: the residue on a 80 mm square hole sieve is ≤10%.

[0019] The third aspect of the present invention provides a solidifying material for filling, comprising a geopolymer-based curing agent prepared according to the above-mentioned preparation method and engineering slag; wherein the weight ratio of the geopolymer-based curing agent to the engineering slag is 1:4-9, and the engineering slag includes construction waste slag, earth and stone slag, road construction slag, water conservancy project slag, subway slag and / or urban construction slag.

[0020] The fourth aspect of the present invention provides a method for preparing the above-mentioned solidified material for filling, which specifically comprises: uniformly mixing the geopolymer-based solidifying agent and the construction waste soil according to the designed proportion, adding water, stirring and solidifying the mixture.

[0021] Preferably, after the curing agent and construction waste are evenly mixed in proportion, 20% to 30% of water accounting for the total weight of the mixture is added, and the mixture is mixed in a mortar mixer according to the standard mortar mixing procedure. The standard mortar mixing procedure can be adaptively selected according to the requirements of the on-site construction party, and then the mixture is pumped to the pre-filled space and naturally cured.

[0022] The beneficial effects obtained by the present invention are as follows: the geopolymer-based curing agent provided by the present invention is completely made of geopolymer as raw material, and a geopolymer-based curing agent with a net slurry fluidity that meets the requirements can be obtained without using cement. The slump of the obtained concrete mixture and the shrinkage rate of the solidified material after the mixture is solidified can meet the relevant standard requirements, and are superior to the commercially available soft soil curing agent using cement and calcium sulfate as raw materials. It provides a new idea for the reuse of a large amount of engineering waste soil, realizes "green and environmental protection" in the entire process, and is of great significance to environmental protection and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 , (a) is a photograph of the geopolymer-based curing agent obtained in Example 1, and (b) is a photograph of the commercially available soft soil curing agent in Comparative Example 7;

[0024] Figure 2 The XRD patterns of the curing agents in Examples 1 to 2 and Comparative Example 7 are shown in FIG. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] Although the existing geopolymer-based curing agents have solved the problem of easy shrinkage and cracking, they still have the problem of high viscosity, which reduces the workability of the curing agent and increases the difficulty of construction. In view of this, the present invention provides a geopolymer-based curing agent, the raw materials of which are all industrial solid wastes, and there is no need to use high-cost cement, and the net slurry fluidity of the obtained geopolymer-based curing agent is moderate. After being applied to engineering slag, the obtained solidified material has good shrinkage controllability and workability, and can be constructed by pumping, and the construction efficiency is significantly improved.

[0027] In the following examples and comparative examples, the particle size of the calcium-based solid waste raw material used is not more than 48 mm; the specific surface area of ​​the aluminosilicate solid waste used is ≥350 m 2 / kg; the fineness of the obtained curing agent: the residue on 80mm square hole sieve is ≤10%, and the moisture content is ≤1%.

[0028] Embodiment 1 to Embodiment 6

[0029] Embodiments 1 to 6 of the present invention all provide a geopolymer-based curing agent, and the specific raw material composition and proportion thereof are shown in Table 1.

[0030] Comparative Example 1

[0031] This comparative example provides a geopolymer-based curing agent, and its specific raw material composition and proportion are shown in Table 1. The difference between this comparative example and Example 1 is that the slag powder is replaced by steel slag powder, and the other components and amounts are the same as those in Example 1.

[0032] Comparative Example 2

[0033] This comparative example provides a geopolymer-based curing agent, and its specific raw material composition and proportion are shown in Table 1. The difference between this comparative example and Example 1 is that the slag powder is replaced with lithium slag powder, and the other components and amounts are the same as those in Example 1.

[0034] Comparative Example 3

[0035] This comparative example provides a geopolymer-based curing agent, and its specific raw material composition and proportion are shown in Table 1. The difference between this comparative example and Example 1 is that the slag powder is replaced by coal gasification slag powder, and the other components and amounts are the same as those in Example 1.

[0036] Comparative Example 4

[0037] This comparative example provides a geopolymer-based curing agent, and its specific raw material composition and proportion are shown in Table 1. The difference between this comparative example and Example 1 is that no plasticizer and surface modifier are added.

[0038] Comparative Example 5

[0039] This comparative example provides a geopolymer-based curing agent, and its specific raw material composition and proportion are shown in Table 1. The only difference between this comparative example and Example 1 is that no surface modifier is added.

[0040] Comparative Example 6

[0041] This comparative example provides a geopolymer-based curing agent, and its specific raw material composition and proportion are shown in Table 1. The only difference between this comparative example and Example 1 is that no mineral regulator is added.

[0042] Comparative Example 7

[0043] In this comparative example, a commercially available soft soil solidifying agent was used as the solidifying agent.

[0044] Table 1 Raw material composition and proportion of curing agent corresponding to Examples 1 to 6 and Comparative Examples 1 to 6

[0045]

[0046] Application Examples 1 to 13

[0047] Application Examples 1 to 13 of the present invention respectively use the curing agents provided in Examples 1 to 6 and Comparative Examples 1 to 7 to prepare the curing materials for filling, and the preparation method is: the curing agent and the engineering slag are mixed evenly according to the designed proportion, 25% of the total weight of the mixture is added and stirred to obtain a concrete mixture, and the corresponding curing materials are naturally cured. The proportions of the components in each application example are shown in Table 2.

[0048] Table 2

[0049]

[0050] Test Example 1

[0051] The geopolymer-based curing agents obtained in Examples 1 to 6 and Comparative Examples 1 to 6 and the cured materials obtained in Application Examples 1 to 13 were respectively subjected to performance tests. The net slurry fluidity of the curing agent and the unconfined compressive strength of the corresponding cured material were tested according to the standard "Soft Soil Curing Agent" (CJ / T 526-2018), the slump of the corresponding concrete mixture was tested according to the standard "Standard for Test Methods for Performance of Ordinary Concrete Mixtures" (GB / T 50080-2016), and the shrinkage of the corresponding cured material was tested according to the standard "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" (GB / T50080-2024). The test results are shown in Table 3.

[0052] Table 3

[0053]

[0054] From the test results in Table 3, it can be seen that the 7d and 28d unconfined compressive strengths of the cured material obtained by using the geopolymer-based curing agent provided by the present invention are much higher than the 7d / 28d compressive strength standard required by the "Soft Soil Curing Agent" (CJ / T 526-2018) standard, and compared with the commercially available soft soil curing agent (Comparative Example 7), both the early strength and the late strength are greatly improved. The geopolymer-based curing agents of Examples 1 to 3 have excellent shrinkage performance, which is mainly manifested in that when in an alkaline environment, the hydration and hardening rate is relatively fast, and the formed Si-O-Al three-dimensional network gel structure has higher mechanical strength; in addition, from the results of Example 1 and Comparative Example 6, it can be seen that the addition of a mineral regulator can make the formed Si-O-Al three-dimensional network gel structure have better stability performance, can effectively reduce the shrinkage rate, and meet the requirements of low settlement rate and high top connection rate during underground filling. It can be seen from Examples 1 to 6 that aluminosilicate solid waste can meet the standard performance requirements within the limited range of 25% to 45%, and this range is more appropriate from the perspective of mechanical stability and economy. It can be seen from Comparative Examples 1 and 3 that although steel slag and coal gasification slag contribute more to strength, steel slag fine powder is not easy to grind, and steel slag and coal gasification slag have a greater impact on the fluidity of the curing agent, and the loss rate after 30min and 60min is high, which is not suitable for this system. It can be seen from Comparative Examples 4 and 5 that the plasticizer has a significant effect on improving fluidity, and has a positive effect on the fluidity of the curing agent and the shrinkage rate of the cured material, while the surface modifier can improve water retention, enhance surface tension and reduce shrinkage.

[0055] Test Example 2

[0056] XRD tests were performed on the curing agents in Examples 1 to 2 and Comparative Example 7, and the test results are as follows: Figure 2 As shown. It can be seen that the peak value of the commercial curing agent calcium sulfate is the highest, which can be inferred that it still uses traditional cement and CaSO4 as raw materials, while the product of the present invention utilizes the gypsum component in the calcium-based solid waste in the geopolymer and the active silicon-aluminum-based solid waste to participate in the reaction in an alkaline environment (provided by carbide slag, the main component calcium oxide reacts with water to generate calcium hydroxide).

[0057] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A geopolymer-based curing agent, characterized in that: The raw material composition of the geopolymer-based curing agent includes, by weight ratio: 25% to 45% of aluminosilicate solid waste, 10% to 30% of fly ash, 10% to 30% of calcium-based solid waste, 5% to 15% of mineral regulator, 0.05% to 0.1% of plasticizer, and 0.005% to 0.01% of surface modifier; Wherein, the mineral regulator is selected from at least one of bentonite and calcium sulphoaluminate type expansion agent.

2. The geopolymer-based curing agent according to claim 1, characterized in that The aluminosilicate solid waste is silicate solid waste and / or aluminate solid waste.

3. The geopolymer-based curing agent according to claim 1 or 2, characterized in that: The specific surface area of ​​the aluminosilicate solid waste is ≥350m 2 / kg.

4. The geopolymer-based curing agent according to claim 1, characterized in that The calcium-based solid waste is selected from at least one of desulfurized gypsum, phosphogypsum, industrial dihydrate gypsum and industrial hemihydrate gypsum, and carbide slag.

5. The geopolymer-based curing agent according to claim 4, characterized in that The particle size of the calcium-based solid waste does not exceed 48 mm.

6. The geopolymer-based curing agent according to claim 1, characterized in that The plasticizer is selected from at least one of sodium lignin sulfonate, catechol and triethanolamine.

7. The geopolymer-based curing agent according to claim 1, characterized in that The surface modifier is selected from at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, hydroxypropyl methylcellulose and polyacrylamide.

8. The method for preparing a geopolymer-based curing agent according to any one of claims 1 to 7, characterized in that: The aluminosilicate solid waste, fly ash, calcium-based solid waste, mineral regulator, plasticizer and surface modifier are added into a mixer according to the designed proportion and mixed evenly to obtain the geopolymer-based curing agent.

9. A solidifying material for filling, characterized in that: It comprises a geopolymer-based curing agent prepared according to the preparation method of claim 8 and engineering slag; The weight ratio of the geopolymer-based curing agent to engineering slag is 1:4-9, and the engineering slag includes construction waste slag, earthwork slag, road construction slag, water conservancy engineering slag, subway slag and / or urban construction slag.

10. The method for preparing the solidified material for filling according to claim 9, characterized in that: The geopolymer-based curing agent and construction waste soil are mixed evenly according to the designed proportion, and then water is added, stirred and cured to obtain the product.

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