Cement plant solid waste-based high-water-solid-ratio grouting material and application thereof

Abstract

The application belongs to the technical field of composite materials, and discloses a high-water-solid-ratio grouting material based on cement plant solid waste and application thereof. The grouting material comprises two components A and B. The component A is mainly formed by uniformly mixing 60-80 parts of stone powder and 20-30 parts of cement. The component B is mainly formed by uniformly mixing 5-20 parts of an activator, 1-3 parts of superabsorbent resin and 100-150 parts of water. The superabsorbent resin is one or more of starch polymers and cellulose polymers. The grouting material can not only ensure high fluidity of the grouting material on the basis of a large amount of solid waste, but also avoid the adverse effect of high water-solid ratio on the early strength of the grouting material, and can be used in the fields of goaf treatment and loose foundation reinforcement.

Description

Technical Field

[0001] This invention belongs to the field of composite materials, specifically relating to a high water-to-solid ratio grouting material based on cement plant solid waste and its application. Background Technology

[0002] The flow process of grout is the result of the interaction between the grout (grouting material) and the injected medium. The selection of grouting material is one of the key conditions for surrounding rock reinforcement and seepage prevention, especially for projects such as urban underground spaces more than 200 meters below the surface, which has significant practical implications. If a mining subsidence area causes surface damage, it will directly lead to subsidence or tensile deformation of the highway subgrade, posing a significant threat to the stability of the subgrade and structures. Currently, most measures for treating mining subsidence areas under highways adopt grouting filling schemes. This involves evenly distributing grouting holes at a certain spacing in the mining subsidence area and injecting cement or fly ash grout under high pressure. The grout fills and permeates the cavities or rock fissures in the strata, ensuring the safety of the highway.

[0003] Commonly used cement slurries include single-liquid cement slurry, cement-fly ash slurry, cement-clay slurry, and cement-water glass two-liquid slurry. For example, cement-fly ash slurry is commonly used in combination with local coarse sand or stone chips and injected into the goaf. The cement-fly ash slurry is mainly composed of water, cement, fly ash, and accelerator. The water is local river water, the cement is PO 32.5 ordinary Portland cement, the fly ash is the initial discharge product of the power plant, and the accelerator is water glass. Its water-to-solid ratio is 1:(1-1.5). Cement accounts for about 30%-50% of the solid phase, and fly ash accounts for about 70%-50% of the solid phase. 1%-2% of the cement weight of the accelerator is added to the slurry to make the slurry injected into the goaf solidify as soon as possible and prevent slurry loss. Although this type of material has the advantages of abundant raw material sources, low price and high specimen strength, it also has disadvantages such as long gelation time which is not easy to control accurately, high water absorption, poor stability and slow strength growth rate. In addition, it is easy to leak grout in large pore formations and poor injectability in small pore formations, making it difficult to guarantee the grouting quality.

[0004] Cement plant solid waste refers to a type of solid waste generated from the dust and particles produced during the crushing, firing, loading, and transportation of cement. It is a newly emerging type of solid waste due to the strengthening of environmental protection measures. Composition analysis reveals that the main components of this type of solid waste are carbonates, silicates, and a small amount of cement clinker, making it possible to use stone powder from cement plant solid waste to prepare grouting materials. Summary of the Invention

[0005] In view of the problems and shortcomings of the existing technology, the purpose of this invention is to provide a high water-to-solid ratio grouting material based on cement plant solid waste and its application.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a grouting material, the grouting material comprising two components, A and B;

[0008] Component A is mainly composed of the following raw materials in parts by weight: 60-80 parts stone powder and 20-30 parts cement.

[0009] Component B is mainly composed of the following raw materials in parts by weight: 5-20 parts activator, 1-3 parts superabsorbent resin, and 100-150 parts water.

[0010] The superabsorbent resin is one or more of cellulose polymers and starch polymers.

[0011] Preferably, the activator is a composition of an alkali metal hydroxide, a water-soluble silicate, and a water-soluble sulfate. More preferably, the activator is a composition of sodium hydroxide, sodium silicate, and sodium sulfate. Further, in the activator, the molar ratio of sodium hydroxide, sodium silicate, and sodium sulfate is (1-10):(2-40):(2-40).

[0012] Preferably, the stone powder is calcareous rock matrix powder. More preferably, the stone powder is limestone powder, which is rich in CaCO3 and reacts with water-soluble silicates in the alkali activator to form CaSiO3.

[0013] Preferably, the water absorption rate of the cellulose polymer is 600%-800%; the cellulose polymer is a cellulose-grafted acrylate polymer or / and a carboxymethyl cellulose-grafted acrylate polymer.

[0014] Preferably, the starch polymer has a water absorption rate of 500%-1000%; the starch polymer is a starch-grafted polyacrylonitrile hydrolysis product.

[0015] Preferably, the cement is one or more of ordinary silicate cement, sulfoaluminate cement, and magnesium phosphate cement.

[0016] The second aspect of the present invention provides a method for preparing any of the grouting materials described in the first aspect above. The method involves weighing and mixing all components of component A according to the formula of any of the grouting materials described in the first aspect above, weighing and mixing all components of component B, and then mixing component A and component B in a mass ratio of (1-10):(5-20) and pouring the mixture into the area to be filled.

[0017] The third aspect of this invention provides the application of any of the grouting materials described in the first aspect in the reinforcement and filling of underground spaces, such as filling mining subsidence areas beneath highways and railways, and reinforcing loose foundations.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] (1) This invention prepares a grouting material by mixing solid waste stone powder collected during the cement plant production process with cement, superabsorbent resin, sodium hydroxide (potassium), sodium silicate (potassium), and sodium sulfate (potassium) in a certain proportion. The grouting material provided by this invention not only ensures high fluidity of the grouting material (grouting depth up to 350 meters) while making extensive use of solid waste, but also avoids the adverse effects of a high water-to-solid ratio on the early strength of the grouting material. It can be used in fields such as goaf treatment and loose foundation reinforcement.

[0020] (2) This invention employs a dual-material grouting method. In component B, superabsorbent resin can lock in a large amount of water during the initial stirring stage. When water is needed during the hydration process of the grouting material after components A and B are mixed, the water is gradually released, avoiding the drawback of low early strength caused by a high water-cement ratio in the initial stage. Therefore, the water-to-solid ratio is significantly improved compared to existing grouting materials. In one embodiment, the water-to-solid ratio of this invention reaches 1:1.5. Simultaneously, the early strength of the grouting material of this invention does not decrease under the premise of a high water-to-solid ratio. In one embodiment, the initial flowability of the grouting material of this invention is 19s, the initial setting time is 35min, the 1-day compressive strength is 9.3MPa, the 3-day compressive strength is 29.3MPa, and the 28-day compressive strength is 35.1MPa. In another embodiment, the shrinkage rates of the grouting material of the present invention are 0.2%, 0.03%, and 0.02% at 1 day, 7 days, and 28 days, respectively. Compared with grouting materials without superabsorbent resin, the shrinkage rates at 1 day, 7 days, and 28 days are reduced by 80%, 97%, and 97.5%, respectively.

[0021] (3) This invention relates to a comprehensive utilization technology for solid waste, specifically utilizing stone powder, a solid waste collected from cement plant dust, as the main raw material, replacing increasingly scarce sand and fly ash, making it more environmentally friendly; then, the stone powder is carefully proportioned with activators sodium hydroxide (potassium), sodium silicate (potassium), and sodium sulfate (potassium), utilizing the activity of the activators and the Ca dissolved in the stone powder 2+ CO3 2- SO4 2- When a gelation reaction occurs, insoluble substances such as silicates and sulfates are formed, such as SiO3 in the activator. 2- With Ca dissolved in stone powder 2+ It can form a gel material, which strengthens the stone body and reduces the amount of cement used in the grouting material. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to the embodiments.

[0024] It should be noted that the stone powder used in this embodiment of the invention is derived from solid waste collected from cement plant dust, specifically limestone powder. If other types of stone powder are selected, such as dolomite powder or marble powder, the mass ratio of the activator to the stone powder needs to be adjusted; the molar ratio of sodium hydroxide, sodium silicate, and sodium sulfate in the activator can be adjusted according to the actual situation, specifically based on the Ca content in the stone powder. 2+ Ion-modified SiO3 in the activator 2- The amount of ions used is inherently related to maintaining the Ca²⁺ content as much as possible. 2+ Ions and SiO3 2- The molar ratio of ions is between 1:0.95 and 1:1.05.

[0025] Example 1: The effect of superabsorbent resin type on the fluidity, setting time and strength of grouting material

[0026] To investigate the effects of different types of superabsorbent resins on the initial flowability, initial setting time, compressive strength, and shrinkage rate of grouting materials, the initial flowability of the grouting material was measured using a flow cone assay. The following experiments were conducted: Examples 1-1 to 1-3 and Comparative Example 1-1. The types of superabsorbent resins added were: starch-grafted polyacrylonitrile hydrolysate, cellulose-grafted acrylate polymer, carboxymethyl cellulose-grafted acrylate polymer, polyacrylate, and no superabsorbent resin added. The results are shown in Table 1.

[0027] Example 1-1

[0028] This embodiment provides a grouting material comprising two components, A and B. Component A is composed of the following raw materials in parts by weight: 60 parts stone powder and 30 parts cement. Component B is composed of the following raw materials in parts by weight: 10 parts activator, 1 part starch-grafted polyacrylonitrile hydrolysis product, and 100 parts water. The activator is composed of sodium hydroxide, sodium silicate, and sodium sulfate, with a molar ratio of 1:10:3.

[0029] This embodiment also provides a method for preparing the above-mentioned grouting material: weigh all the components of component A according to the above-mentioned grouting material formula and stir them evenly; weigh all the components of component B and stir them evenly; then mix component A and component B in a mass ratio of 1:1 and pour them into the area to be filled.

[0030] Examples 1-2

[0031] The content of the grouting material is basically the same as that of Example 1-1, except that the starch-grafted polyacrylonitrile hydrolysis product is replaced with cellulose-grafted sodium acrylate.

[0032] The preparation method of a grouting material is basically the same as that of Example 1-1, except that the grouting material formula is the same as that of this example.

[0033] Examples 1-3

[0034] The content of the grouting material is basically the same as that of Example 1-1, except that the starch-grafted polyacrylonitrile hydrolysis product is replaced with carboxymethyl cellulose-grafted sodium acrylate.

[0035] The preparation method of a grouting material is basically the same as that of Example 1-1, except that the grouting material formula is the same as that of this example.

[0036] Comparative Example 1-1

[0037] The content of the grouting material is basically the same as that of Example 1-1, except that the starch-grafted polyacrylonitrile hydrolysis product is replaced with sodium polyacrylate.

[0038] The preparation method of a grouting material is basically the same as that of Example 1-1, except that the grouting material formula is the same as that of this example.

[0039] Comparative Examples 1-2

[0040] The content of the grouting material is basically the same as that of Example 1-1, except that: no starch-grafted polyacrylonitrile hydrolysis product is added.

[0041] The preparation method of a grouting material is basically the same as that of Example 1-1, except that the grouting material formula is the same as that of this example.

[0042] Table 1 Performance parameters of the grouting materials prepared in Example 1 and Comparative Example 1

[0043]

[0044] As shown in Table 1, comparing Example 1 with Comparative Example 1 reveals that the addition of superabsorbent resin has a limited impact on the fluidity and mechanical properties of the grout. This is mainly because, compared to high water-to-solid ratio systems, the mechanical properties of concrete after solidification primarily depend on the aggregate mix ratio, while excess water is no longer present in the concrete after the grout has solidified. Comparing Example 1 with Comparative Example 1-1 shows that, with changes in the type of superabsorbent resin, the grout prepared with carboxymethyl cellulose-grafted acrylate polymer superabsorbent resin exhibits relatively higher initial fluidity, a relatively longer initial setting time, and relatively higher compressive strength.

[0045] In terms of shrinkage rate, comparing Example 1 with Comparative Example 1 shows that the shrinkage rates of the superabsorbent resins are both relatively small. This is because the addition of superabsorbent resins adsorbs excess water in the system and releases it slowly during the solidification process of the grout. This ensures good workability (flowability) of the grout during the construction stage, while preventing rapid water loss that could cause shrinkage and cracking during solidification. Specifically, Examples 1-3 show significantly smaller shrinkage rates compared to Comparative Example 1-1. This is mainly because the different types of superabsorbent resins result in variations in their water absorption and release effects in the grout, thus affecting the shrinkage rate of the grout.

[0046] Therefore, carboxymethyl cellulose grafted acrylate polymers can ensure good fluidity of the grouting material, while significantly reducing the yield after solidification. Thus, carboxymethyl cellulose grafted acrylate polymer compounds are preferred as superabsorbent resins to be added to the grouting material.

[0047] Example 2: Effect of superabsorbent resin dosage on the fluidity, setting time, and strength of grouting materials

[0048] To investigate the effect of superabsorbent polymer (SAP) dosage on the initial flowability, initial setting time, and compressive strength of the grouting material, the initial flowability of the grouting material was measured using a flow cone assay. The following experiments were conducted: Examples 1-3 and Examples 2-1 to 2-3, with corresponding amounts of SAP added: 1 part, 1.5 parts, 2 parts, and 3 parts, respectively. The results are shown in Table 2.

[0049] Example 2-1

[0050] The contents of the grouting material are basically the same as those in Examples 1-3, except that the amount of sodium acrylate grafted with carboxymethyl cellulose is 1.5 parts.

[0051] The preparation method of a grouting material is basically the same as that of Examples 1-3, except that the grouting material formula is the same as that of this example.

[0052] Example 2-2

[0053] The contents of the grouting material are basically the same as those in Examples 1-3, except that: the amount of sodium acrylate grafted with carboxymethyl cellulose is 2 parts.

[0054] The preparation method of a grouting material is basically the same as that of Examples 1-3, except that the grouting material formula is the same as that of this example.

[0055] Example 2-3

[0056] The contents of a grouting material are basically the same as those in Examples 1-3, except that: the amount of sodium acrylate grafted with carboxymethyl cellulose is 3 parts.

[0057] The preparation method of a grouting material is basically the same as that of Examples 1-3, except that the grouting material formula is the same as that of this example.

[0058] Table 2 Performance parameters of grouting materials containing carboxymethyl cellulose grafted sodium acrylate

[0059]

[0060] As shown in Table 2, with the increase of the amount of superabsorbent polymer (SARP) grafted with sodium acrylate, the initial fluidity of the grouting material gradually increases, the initial setting time gradually increases, and the compressive strength first increases and then decreases. This is because the addition of SARP adsorbs some water, reducing the fluidity of the grouting material, prolonging the initial setting time, and strengthening the compressive strength to some extent; however, as the proportion of SARP further increases, it is not conducive to improving the overall compressive strength of the concrete. Therefore, it is preferable to add 2 parts of SARP grafted with sodium acrylate polymer to the grouting material in this embodiment.

[0061] Example 3: Effect of the mass ratio of stone powder to activator on the initial fluidity, setting time, and compressive strength of grouting materials

[0062] To investigate the effect of the mass ratio of stone powder to activator on the initial fluidity, initial setting time, and compressive strength of the grouting material, the initial fluidity of the grouting material was measured using a flow cone assay. The following experiments were conducted: Examples 2-2, 3-1 to 3-3, and Comparative Example 3-1, with corresponding amounts of activator added: 10 parts, 5 parts, 15 parts, 20 parts, and 0 parts, respectively. The results are shown in Table 3.

[0063] Example 3-1

[0064] The contents of the grouting material are basically the same as those in Examples 2-2, except that the activator is 5 parts.

[0065] The preparation method of a grouting material is basically the same as that in Examples 2-2, except that the grouting material formula is the same as that in this example.

[0066] Example 3-2

[0067] The contents of the grouting material are basically the same as those in Examples 2-2, except that the activator is 15 parts.

[0068] The preparation method of a grouting material is basically the same as that in Examples 2-2, except that the grouting material formula is the same as that in this example.

[0069] Example 3-3

[0070] The contents of the grouting material are basically the same as those in Examples 2-2, except that the activator is 20 parts.

[0071] The preparation method of a grouting material is basically the same as that in Examples 2-2, except that the grouting material formula is the same as that in this example.

[0072] Comparative Example 3-1

[0073] The contents of the grouting material are basically the same as those in Examples 2-2, except that the activator is 0 parts.

[0074] The preparation method of a grouting material is basically the same as that in Examples 2-2, except that the grouting material formula is the same as that in this example.

[0075] Table 3 Performance parameters of grouting materials with different activator dosages

[0076]

[0077] Table 3 shows that, comparing the examples and comparative examples, the addition of the activator had little effect on the fluidity of the grout, but a significant impact on its initial setting time and mechanical properties. When the activator dosage was 15 parts, the grout had the shortest initial setting time and the highest compressive strength at 1 day, 3 days, and 28 days. This is because the addition of the activator can react with the Ca in the stone powder... 2+ A gelling reaction occurs, improving the mechanical properties of the grout. Because there is an optimal molar ratio between the activator and the effective components of stone powder, the amount of activator needs to be adjusted in different systems to obtain the best performance.

[0078] Example 4: Effect of water-to-solid ratio on the fluidity, setting time and strength of grouting materials

[0079] To investigate the effects of water-to-solid ratio on the initial fluidity, initial setting time, and compressive strength of grouting materials, the initial fluidity of the grouting materials was measured using a flow cone assay. The following experiments were conducted: Examples 3-2, 4-1 to 4-3, with corresponding amounts of activator added of 100, 120, 140, and 150 parts, respectively.

[0080] Example 4-1

[0081] The contents of the grouting material are basically the same as those in Examples 3-2, except that the water content is 120 parts.

[0082] The preparation method of a grouting material is basically the same as that of Examples 3-2, except that the grouting material formula is the same as that of this example.

[0083] Example 4-2

[0084] The contents of the grouting material are basically the same as those in Examples 3-2, except that the water content is 140 parts.

[0085] The preparation method of a grouting material is basically the same as that of Examples 3-2, except that the grouting material formula is the same as that of this example.

[0086] Example 4-3

[0087] The contents of the grouting material are basically the same as those in Examples 3-2, except that the water content is 150 parts.

[0088] The preparation method of a grouting material is basically the same as that of Examples 3-2, except that the grouting material formula is the same as that of this example.

[0089] Table 4 Performance parameters of grouting materials in the examples

[0090]

[0091] As shown in Table 4, with the increase of water content, the water-to-solid ratio of the grouting material increases, and the initial fluidity of the grouting material shows an increasing trend, although not very significant. The initial setting time also shows an increasing trend, while the compressive strength shows a decreasing trend. This is because the increased water content in the system after the water-to-solid ratio increases the fluidity of the grouting material, but at the same time, the increase in water also increases the difficulty of the grouting material's gelation. With the continuous increase of water content, the gelation process of the grouting material becomes increasingly difficult, and the mechanical properties after gelation are significantly reduced. Therefore, it is preferable to add 100 parts of water to the grouting material in this embodiment.

[0092] In summary, this invention effectively overcomes the shortcomings of the prior art and has high industrial applicability. The above embodiments are intended to illustrate the substantive content of this invention, but are not intended to limit the scope of protection of this invention. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this invention without departing from the essence and scope of protection of this invention.

Claims

1. A grouting material, characterized in that, The grouting material comprises two components, A and B; the mass ratio of component A to component B is (1-10):(5-20). Component A is mainly composed of the following raw materials in parts by weight: 60-80 parts stone powder and 20-30 parts cement. Component B is mainly composed of the following raw materials in parts by weight: 5-20 parts activator, 1-3 parts superabsorbent resin, and 100-150 parts water. The superabsorbent resin is one or more of cellulose polymers and starch polymers; the cellulose polymer is a cellulose-grafted acrylate polymer or / and a carboxymethyl cellulose-grafted acrylate polymer; the starch polymer is a starch-grafted polyacrylonitrile hydrolysis product. The activator is a composition of sodium hydroxide, sodium silicate and sodium sulfate, wherein the molar ratio of sodium hydroxide, sodium silicate and sodium sulfate is (1-10):(2-40):(2-40).

2. The grouting material according to claim 1, characterized in that, The stone powder is calcareous rock matrix powder.

3. The grouting material according to claim 1 or 2, characterized in that, The cement is one or more of ordinary silicate cement, sulfoaluminate cement, and magnesium phosphate cement.

4. Process for the production of a grouting material according to any one of claims 1 to 3, characterized in that According to the grouting material formulation of any one of claims 1-3, weigh out all the components of component A and stir them evenly, weigh out all the components of component B and stir them evenly; then mix component A and component B in a mass ratio of (1-10):(5-20) and pour them into the area to be filled.

5. The application of the grouting material according to any one of claims 1-3 in the reinforcement and filling of underground spaces.

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