Waste slag soil solidified unfired brick

Abstract

The invention relates to the technical field of slag unfired brick building materials and discloses a slag solidified unfired green brick. The slag solidified green brick comprises the following formula: 1500-1600 parts by weight of slag, 20-30 parts by weight of polypropylene fiber, 150-170 parts by weight of a curing agent, 3-8 parts by weight of a powder strengthening agent, 0.5-3 parts by weight of a hyperbranched naphthalene-based water reducer, and 180-190 parts by weight of water. The hyperbranched naphthalene-based water reducer is prepared by the following method: using naphthalene as a raw material, first subjecting the raw material to sulfonation with concentrated sulfuric acid, and then subjecting the raw material to a condensation reaction with branched naphthol phosphate and formaldehyde. The slag solidified unfired green brick has excellent compressive strength and can meet the performance standard of MU15 tailings bricks in JC / T422-2007 "Non-sintered Waste Tailings Bricks".

Description

Technical Field

[0001] The invention relates to the technical field of waste slag unfired brick building materials, in particular to a waste slag solidified unfired green brick. Background Art

[0002] Construction waste is waste soil generated during construction projects such as tunnels, subways, foundation pits, and underground pipeline corridors. Currently, this waste is typically transported directly to remote locations like the suburbs, where it is disposed of through open-air storage, incineration, and landfill. This storage can lead to a range of problems, including occupying significant land, polluting the surrounding environment, and impacting the cityscape.

[0003] In order to improve the comprehensive utilization rate and added value of waste slag, the use of soil solidification technology to produce slag unburned bricks has gradually become an industry development trend. For example, the invention patent application with publication number CN111825375A discloses a method for solidifying and treating slag and preparing unburned bricks, in which slag, cement, acrylic acid, magnesium chloride, water and other raw materials are stirred, mixed, matured, and pressed into shape to achieve harmless solidification of slag and prepare unburned bricks; the invention patent with authorization number CN107285727B squeezes and dehydrates mud slag, mixes it with a soil coagulant, and then makes bricks. Unburned bricks do not need to be sintered to generate strength, which overcomes the shortcomings of ordinary sintered clay bricks that consume a lot of coal resources, consume a lot of energy, and pollute the environment. It is in line with the trend of waste utilization, soil and energy saving, green environmental protection, and sustainable development.

[0004] Waste slag solidified unfired bricks are products made by adding curing agents (cement, lime, fly ash, slag), water reducers (naphthalene-based water reducers, polycarboxylic acid water reducers, melamine-based water reducers, phosphoric acid water reducers), and other additives (powder strengtheners, mud inhibitors, antifreeze agents) to waste slag, and then curing and pressing them into shape through physical, chemical, and combined effects. The water reducer promotes the formation of hydration products, reduces voids during the waste slag solidification process, and improves the compaction performance and mechanical strength of the unfired bricks. It is a key component of waste slag solidified unfired bricks. Summary of the Invention

[0005] The present invention independently develops a waste soil solidified unfired green brick, which has excellent compressive strength and can meet the performance standard of tailings bricks with strength grade MU15 in JC / T 422-2007 "Non-fired waste tailings bricks".

[0006] A waste slag soil solidified unfired green brick, the raw material formula of the waste slag soil solidified unfired green brick is:

[0007] Waste soil, 1500-1600 parts by weight;

[0008] Polypropylene fiber, 20-30 parts by weight;

[0009] Curing agent, 150-170 parts by weight;

[0010] Powder strengthener, 3-8 parts by weight;

[0011] Hyperbranched naphthalene water reducer, 0.5-3 parts by weight;

[0012] Water, 180-190 parts by weight;

[0013] The preparation method of the hyperbranched naphthalene water reducer is as follows: naphthalene is used as a raw material, first sulfonated with concentrated sulfuric acid, and then condensed with branched naphthol phosphate and formaldehyde to obtain the hyperbranched naphthalene water reducer;

[0014] The branched naphthol phosphate is a three-branched naphthol phosphate or a four-branched naphthol phosphate;

[0015] Preferably, the formula of the curing agent is: 5-10 parts by weight of a chemical special soil curing agent, 25-35 parts by weight of quicklime and 120-125 parts by weight of cement.

[0016] Preferably, the powder strengthener is starch or polyvinyl alcohol.

[0017] Preferably, the method for preparing the waste soil solidified unfired green bricks is:

[0018] Step 1: Pretreatment of waste soil: crush the waste soil with a water content of less than 60% into 3-7mm waste soil using a gear clay crusher for later use;

[0019] Step 2: According to the formula of waste slag soil solidified unfired green bricks, polypropylene fiber, chemical special soil solidifier, quicklime, cement, starch and hyperbranched naphthalene water reducer are mixed evenly and then mixed with waste slag soil, water is added and stirred, and after stirring evenly, the mixture is placed in a mold and pressed. The mixture is statically pressed for 8-12 seconds at a pressure of 15-25 MPa and steam-cured at 70-90°C for 20-30 hours or naturally cured at 15-25°C for 25-30 days to obtain waste slag soil solidified unfired green bricks.

[0020] Preferably, the compressive strength of the waste soil solidified unfired bricks is >18MPa.

[0021] Beneficial effects:

[0022] The invention synthesizes two branched naphthol phosphates based on molecular design mechanism, and carries out condensation reaction with sulfonated naphthalene and formaldehyde to prepare hyperbranched naphthalene-based water reducer;

[0023] Waste slag soil is used as raw material, polypropylene fiber is used as anti-cracking reinforcing agent, chemical special soil curing agent, quicklime and cement are used as curing agents, starch is used as powder strengthening agent, and hyperbranched naphthalene series water reducer is used as water reducer. After being mixed evenly, the mixture is pressed into shape to prepare a waste slag soil curing unfired green brick.

[0024] The experimental results show that compared with conventional unfired green bricks prepared using conventional naphthalene-based water reducers, the unfired green bricks prepared using the newly developed hyperbranched naphthalene-based water reducer in the present invention have achieved beneficial technical effects of significantly improved compressive strength performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a bar chart showing the performance test results of unfired bricks solidified with waste slag soil.

[0026] Figure 2 is the chemical structural formula of a three-branched naphthol monomer;

[0027] Figure 3 It is the chemical structural formula of three-branched naphthol phosphate;

[0028] Figure 4 is the chemical structural formula of a tetra-branched naphthol monomer;

[0029] Figure 5 It is the chemical structural formula of tetra-branched naphthol phosphate. DETAILED DESCRIPTION

[0030] Example 1:

[0031] A waste soil solidified unfired green brick, the raw material formula of which is shown in Table 1;

[0032] Table 1 Raw material formula of waste slag soil solidified unfired green bricks

[0033]

[0034]

[0035] The hyperbranched naphthalene water reducer is hyperbranched naphthalene water reducer I or hyperbranched naphthalene water reducer II. The preparation method of hyperbranched naphthalene water reducer I is described in Experimental Example 1, and the preparation method of hyperbranched naphthalene water reducer II is described in Experimental Example 2.

[0036] Example 2:

[0037] A method for preparing waste slag soil solidified unfired green bricks, comprising the following steps:

[0038] Step 1: Pretreatment of waste soil: crush the waste soil with 50% water content into 5mm soil using a gear clay crusher for later use;

[0039] Step 2: According to the formula of the waste soil solidified unfired green brick in Table 1, polypropylene fiber, chemical special soil curing agent, quicklime, cement, starch and hyperbranched naphthalene water reducer are mixed evenly with the waste soil, water is added according to the ratio and stirred for 30 minutes, 140g of the stirred sample is weighed, placed in a mold and pressed, and statically pressed for 10s under a pressure of 20MPa (the test blocks are all 40mm×40mm×40mm cubic blocks), and steam cured at 80°C for 24h to obtain waste soil solidified unfired green bricks;

[0040] When the hyperbranched naphthalene water reducer is hyperbranched naphthalene water reducer I, the prepared product is recorded as waste slag solidified unfired green brick I;

[0041] When the hyperbranched naphthalene-based water reducer is hyperbranched naphthalene-based water reducer II, the prepared product is recorded as waste slag soil solidified unfired green brick II.

[0042] Comparative Example:

[0043] Preparation of conventional unfired green bricks: conventional naphthalene-based water reducer is used instead of the hyperbranched naphthalene-based water reducer in the waste slag soil solidified unfired green bricks, and conventional unfired green bricks are prepared according to the same steps and conditions;

[0044] Among them, the preparation method of conventional naphthalene-based water reducer is described in Experimental Example 3.

[0045] Performance testing:

[0046] (1) Mechanical properties test: The specimens cured at 80°C for 24 h were cooled to room temperature and tested using a YAW-300YD constant stress pressure testing machine with a maximum output pressure of 300 kN and a set loading speed of 2.4 kN / s. The compressive strength of the specimens was recorded.

[0047] (2) Test the water absorption and softening coefficient of the test blocks in accordance with GB / T 4111-2013 “Test methods for concrete blocks and bricks”;

[0048] The above experimental results are shown in Table 2 and Figure 1 .

[0049] Table 2 Performance test results of waste slag soil solidified unfired bricks

[0050] Product Type Compressive strength (MPa) Water absorption (%) Softening coefficient Unfired green bricksⅠ 18.7 10.2 0.79 Unfired green bricks Ⅱ 21.4 9.5 0.85 Comparative Example 13.2 7.6 0.81 Technical requirements ≥15 ≤18 ≥0.8

[0051] Note: The technical requirements are based on the performance of tailings bricks with strength grade MU15 in JC / T 422-2007 "Non-sintered waste tailings bricks";

[0052] By comprehensively analyzing the above experimental results, the following conclusions can be drawn:

[0053] Conclusion 1: Compared with conventional unfired green bricks prepared using conventional naphthalene-based water reducers, the unfired green bricks prepared using the newly developed hyperbranched naphthalene-based water reducer in the present invention have achieved a significant improvement in compressive strength performance;

[0054] Among them, the hyperbranched naphthalene water reducer II prepared from tetra-branched naphthol phosphate has a better effect on improving the compressive strength of unfired green bricks;

[0055] The mechanism for the above experimental results may be that the hyperbranched naphthalene-based water reducer increases the contact area between the water reducer molecules and the waste soil and curing agent particles. On the other hand, the spatial structure of the hyperbranched naphthalene-based water reducer can increase the steric hindrance, improve the fluidity of the waste soil and curing agent particles, reduce the voids in the waste soil curing process of the unfired green bricks, and thus improve the compressive strength of the unfired green bricks.

[0056] Conclusion 2: The waste slag soil solidified unfired green bricks prepared by the present invention have excellent comprehensive performance and can meet the performance standard of tailings bricks with strength grade MU15 in JC / T422-2007 "Non-fired waste tailings bricks".

[0057] Experimental Example 1:

[0058] Hyperbranched naphthalene-based water reducer I was prepared as follows:

[0059] (1) Synthesize three-branched naphthol phosphate, its synthesis steps are:

[0060] Step 1: The hydroxyl functional group of glycerol and the carboxyl functional group of 2-hydroxy-6-naphthoic acid undergo esterification reaction to generate a three-branched naphthol monomer, the chemical structure of which is as follows: Figure 2 As shown;

[0061] Step 2: The three-branched naphthol monomer undergoes an esterification reaction with phosphorus oxychloride by catalyzing an organic base catalyst, and then hydrolyzed with water to generate a three-branched naphthol phosphate, whose chemical structure is as follows: Figure 3 As shown;

[0062] The organic base catalyst is one of triethylamine, pyridine, and tetramethylethylenediamine; pyridine is selected in this experimental example;

[0063] The specific experimental steps for preparing three-branched naphthol phosphate are:

[0064] 0.9 g of glycerol, 5.6 g of 2-hydroxy-6-naphthoic acid, and 60 mL of N,N-dimethylformamide were added to a three-necked flask and stirred at room temperature until completely dissolved. 1.2 mL of concentrated sulfuric acid was then added dropwise to the flask, and the temperature was raised to 70° C., stirred, and reacted for 6 h. The flask was washed with N,N-dimethylformamide and deionized water in sequence, the solvent was removed by rotary evaporation, and the flask was dried in vacuo to obtain a three-branched naphthol monomer.

[0065] 3.0 g of a tri-branched naphthol monomer and 50 mL of anhydrous toluene were added to a three-necked flask and stirred at room temperature until completely dissolved. 1.4 mL of phosphorus oxychloride was then added dropwise to the flask. The temperature was raised to 80° C. and 0.6 mL of pyridine was slowly added dropwise. The reaction was maintained at 80° C. with stirring for 5 h. After cooling, the mixture was filtered and distilled under reduced pressure. 100 mL of deionized water was added, and the mixture was stirred for hydrolysis for 2 h. The mixture was filtered and dried under vacuum to obtain a tri-branched naphthol phosphate.

[0066] The nuclear magnetic resonance hydrogen spectrum of the three-branched naphthol phosphate is characterized as follows: 1 H NMR (CDCl3, 400MHz) δ: 4.42-4.44 (d, 4H), 4.94-5.01 (m, 1H), 7.14-8.60 (m, 18H, Ar-H);

[0067] (2) Preparation of hyperbranched naphthalene-based water reducer I: Naphthalene is used as a raw material, first sulfonated with concentrated sulfuric acid, and then condensed with tri-branched naphthol phosphate and formaldehyde to prepare hyperbranched naphthalene-based water reducer I. The specific preparation steps are as follows: 10g of flake industrial naphthalene is heated and melted and then put into a four-necked flask; under the protection of nitrogen, 20mL of concentrated sulfuric acid is added dropwise; the temperature is raised to 160°C and stirred for reaction for 2h; the mixture is cooled to room temperature; deionized water is added to adjust the acid value to 29%; then 2g of tri-branched naphthol phosphate and 3g of formaldehyde are added to the four-necked flask; the temperature is raised to 130°C and stirred for reaction for 12h; the mixture is cooled to room temperature; sodium hydroxide is added to neutralize the mixture to pH=7 to obtain hyperbranched naphthalene-based water reducer I.

[0068] Experimental Example 2:

[0069] Preparation of hyperbranched naphthalene water reducer II, the preparation process is as follows:

[0070] (1) Synthesize four-branched naphthol phosphate, its synthesis steps are:

[0071] Step 1: The hydroxyl functional group of pentaerythritol and the carboxyl functional group of 2-hydroxy-6-naphthoic acid undergo esterification reaction to generate a four-branched naphthol monomer, the chemical structure of which is as follows: Figure 4 As shown;

[0072] Step 2: The tetra-branched naphthol monomer undergoes an esterification reaction with phosphorus oxychloride by catalyzing an organic base catalyst, and then hydrolyzed with water to generate a tetra-branched naphthol phosphate, whose chemical structure is as follows: Figure 5 As shown;

[0073] The organic base catalyst is one of triethylamine, pyridine, and tetramethylethylenediamine; pyridine is selected in this experimental example;

[0074] The specific experimental steps for preparing four-branched naphthol phosphate are:

[0075] 1.3 g of glycerol, 7.5 g of 2-hydroxy-6-naphthoic acid, and 80 mL of N,N-dimethylformamide were added to a three-necked flask and stirred at room temperature until completely dissolved. 1.5 mL of concentrated sulfuric acid was then added dropwise to the flask, and the temperature was raised to 70° C., stirred, and reacted for 8 h. The flask was washed with N,N-dimethylformamide and deionized water in sequence, and the solvent was removed by rotary evaporation. The flask was then dried in vacuo to obtain a tetra-branched naphthol monomer.

[0076] 4.1 g of tetra-branched naphthol monomer and 50 mL of anhydrous toluene were added to a three-necked flask and stirred at room temperature until completely dissolved. 1.9 mL of phosphorus oxychloride was then added dropwise to the flask. The temperature was raised to 80°C and 0.7 mL of pyridine was slowly added dropwise. The reaction was maintained at 80°C with stirring for 6 h. After cooling, the mixture was filtered and distilled under reduced pressure. 100 mL of deionized water was added, and the mixture was stirred for hydrolysis for 2 h. The mixture was filtered and dried under vacuum to obtain tetra-branched naphthol phosphate.

[0077] The nuclear magnetic resonance hydrogen spectrum of the four-branched naphthol phosphate is characterized as follows: 1 H NMR (CDCl3, 400MHz) δ: 4.44 (s, 8H), 7.13-8.62 (m, 24H, Ar-H);

[0078] (2) Preparation of hyperbranched naphthalene water reducer II: Naphthalene is used as a raw material, first sulfonated with concentrated sulfuric acid, and then condensed with tetra-branched naphthol phosphate and formaldehyde to prepare hyperbranched naphthalene water reducer II. The specific preparation steps are different from those of hyperbranched naphthalene water reducer I only in that tetra-branched naphthol phosphate is used to replace tri-branched naphthol phosphate.

[0079] Experimental Example 3:

[0080] Preparation of conventional naphthalene-based water reducer: 10 g of flake industrial naphthalene was heated and melted and then placed in a four-necked flask. Under nitrogen protection, 20 mL of concentrated sulfuric acid was added dropwise, the temperature was raised to 160°C and stirred for 2 h, the mixture was cooled to room temperature, and deionized water was added to adjust the acid value to 29%. Then, 3 g of formaldehyde was added to the four-necked flask, the temperature was raised to 130°C and stirred for 12 h, the mixture was cooled to room temperature, and sodium hydroxide was added to neutralize the mixture to pH = 7 to obtain a conventional naphthalene-based water reducer.

Claims

1. A waste soil solidified unfired green brick, characterized in that: The raw material formula of the waste soil solidified unfired green brick is: Waste soil, 1500-1600 parts by weight; Polypropylene fiber, 20-30 parts by weight; Curing agent, 150-170 parts by weight; Powder strengthener, 3-8 parts by weight; Hyperbranched naphthalene water reducer, 0.5-3 parts by weight; Water, 180-190 parts by weight; The preparation method of the hyperbranched naphthalene water reducer is as follows: naphthalene is used as a raw material, first sulfonated with concentrated sulfuric acid, and then condensed with branched naphthol phosphate and formaldehyde to obtain the hyperbranched naphthalene water reducer; The branched naphthol phosphate is a three-branched naphthol phosphate or a four-branched naphthol phosphate; The chemical structure of the three-branched naphthol phosphate is: The chemical structure of tetra-branched naphthol phosphate is:

2. The waste soil solidified unfired green brick according to claim 1, characterized in that: The preparation method of the three-branched naphthol phosphate is: The hydroxyl functional group of glycerol and the carboxyl functional group of 2-hydroxy-6-naphthoic acid undergo esterification reaction to generate a three-branched naphthol monomer; The tri-branched naphthol monomer undergoes an esterification reaction with phosphorus oxychloride by catalyzing an organic base catalyst, and then water is added to hydrolyze the reaction to generate the tri-branched naphthol phosphate.

3. The waste soil solidified unfired green brick according to claim 1, characterized in that: The preparation method of the four-branched naphthol phosphate is: The hydroxyl functional group of pentaerythritol and the carboxyl functional group of 2-hydroxy-6-naphthoic acid undergo esterification reaction to generate a four-branched naphthol monomer; The tetra-branched naphthol monomer undergoes an esterification reaction with phosphorus oxychloride by catalyzing an organic base catalyst, and then water is added for hydrolysis to generate the tetra-branched naphthol phosphate.

4. The waste soil solidified unfired green brick according to claim 2 or 3, characterized in that: The organic base catalyst is one of triethylamine, pyridine and tetramethylethylenediamine.

5. The waste soil solidified unfired green brick according to claim 1, characterized in that: The formula of the curing agent is: 5-10 parts by weight of a special chemical soil curing agent, 25-35 parts by weight of quicklime and 120-125 parts by weight of cement.

6. The waste soil solidified unfired green brick according to claim 1, characterized in that: The powder strengthener is starch or polyvinyl alcohol.

7. The waste soil solidified unfired green brick according to any one of claims 1 to 3, characterized in that: The preparation method of the waste soil solidified unfired green brick is as follows: Step 1: Pretreatment of waste soil: crush the waste soil with a water content of less than 60% into 3-7mm waste soil using a gear clay crusher for later use; Step 2: According to the formula of waste slag soil solidified unfired green bricks, polypropylene fiber, chemical special soil solidifier, quicklime, cement, starch and hyperbranched naphthalene water reducer are mixed evenly and then mixed with waste slag soil, water is added and stirred, and after stirring evenly, the mixture is placed in a mold and pressed. The mixture is statically pressed for 8-12 seconds at a pressure of 15-25 MPa and steam-cured at 70-90°C for 20-30 hours or naturally cured at 15-25°C for 25-30 days to obtain waste slag soil solidified unfired green bricks.

8. The waste soil solidified unfired green brick according to any one of claims 1 to 3, characterized in that: The compressive strength of the waste soil solidified unfired bricks is greater than 18 MPa.

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