A concrete waste slurry suspension stabilizer material and a preparation method thereof

Abstract

The application discloses a concrete waste slurry suspension stabilizer material and a preparation method thereof, relates to the technical field of building materials, and mainly comprises the following components in percentage by mass: 30-50% anti-segregation components, 20-30% retarding components and 20-40% filling carriers. The preparation process comprises the following steps: adding the filling carriers into the anti-segregation components and the retarding components, uniformly stirring, and then performing spray drying to obtain the concrete waste slurry suspension stabilizer. The concrete waste slurry suspension stabilizer material provided by the application realizes the homogenization and fixation of the concrete waste slurry components, can keep a long-term suspension stable state, and solves the problem that the waste slurry cannot be directly used for preparing concrete.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a concrete waste slurry suspension stabilizer material and its preparation method. Background Technology

[0002] With the acceleration of my country's industrialization and urbanization, and the rapid development of the ready-mixed concrete industry, the consumption of concrete is increasing daily, leading to a rapid increase in waste slurry generated by concrete mixing plants during production. Ready-mixed concrete waste slurry is a solid waste generated during concrete production. During production, excess fresh concrete and wastewater from washing vehicles, cleaning sites, and cleaning mixers are collected in sedimentation tanks for settling. After sedimentation, the lower layer of solid slurry is collected and dewatered using a filter press, ultimately yielding ready-mixed concrete waste slurry. Currently, ready-mixed concrete waste slurry is mostly treated as solid waste after natural drying, forming waste residue. The solid composition of mixing plant waste slurry includes: fine aggregates obtained from the sedimentation tank, hydration products of cementitious materials, residual cementitious material particles, and some unhydrated cement. Generally, the density of the undehydrated waste residue is approximately 1.1 g / cm³. 3 The moisture content is approximately 150%, the solids content ranges from 380 to 63,400 ppm, and most of the waste slurry has a particle size of less than 800 μm.

[0003] According to incomplete statistics, my country's total output of ready-mixed concrete has exceeded 2 billion cubic meters in the past five years. 3 Preliminary estimates suggest that over 90 million tons of waste slag from concrete mixing plants will be processed annually nationwide. Managing, transporting, and disposing of this massive amount of waste will require enormous human, material, and financial resources. Meanwhile, globally, over 125 million tons of freshly mixed, uncured concrete are returned to mixing plants annually as waste due to quality issues. The indiscriminate disposal of this waste slurry and discarded concrete by concrete mixing plants not only wastes reusable resources but also causes severe pollution to the local environment. Concrete mixing plants require significant human and material resources to handle waste, incurring both time and substantial economic costs, thus increasing their production costs. Whether stockpiled or buried, the waste slurry generated by mixing plants occupies large areas of land, resulting in a tremendous waste of land resources.

[0004] Since the waste slurry from concrete mixing plants originates from concrete preparation, reusing it in concrete production not only reduces concrete costs but also achieves true resource utilization of these wastes. Current technologies primarily involve drying, crushing, and grinding the waste slurry from waste concrete for reuse as concrete admixtures. However, this process increases the time and manpower required for the resulting waste slurry powder, resulting in lower activity, utilization rate, and economic efficiency. Drying the waste slurry severely damages the properties of the cementitious materials, significantly reducing the cementitious components in the cement. Although some researchers have employed various methods such as mechanical grinding, high-temperature calcination, and chemical activation to increase the activity of the dried waste slurry powder, these methods offer limited improvement in activity and significantly increase the investment in equipment and capital required for waste recycling.

[0005] Therefore, directly using waste slurry in concrete production is the fundamental solution to the aforementioned problems. The limiting factors for directly using waste slurry in concrete batching production include: Firstly, its composition is complex; waste slurry produced at different times and from different types of concrete varies significantly in composition and contains many impurities. Directly using it in concrete preparation will affect product quality, leading to frequent adjustments to the concrete mix proportions. Secondly, waste slurry cannot maintain a stable suspended state for long periods, easily resulting in segregation and slurry-water separation, severely affecting the workability of concrete. Therefore, it is necessary to use technical means to not only fully homogenize the slurry components to achieve relative stability but also ensure that the slurry remains in a stable suspended state. This is a crucial technical problem that needs to be solved to realize the resource utilization of concrete waste slurry. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a concrete waste slurry suspension stabilizer material and its preparation method, thereby achieving homogenization and fixation of the concrete waste slurry components and maintaining a long-term suspended and stable state, thus solving the problem that waste slurry cannot be directly used for concrete preparation.

[0007] To achieve the above objectives, this invention discloses a concrete waste slurry suspension stabilizer material, the main functional components of which include the following components in mass percentage: 30-50% anti-segregation component, 20-30% retarding component, and 20-40% filler carrier.

[0008] Preferably, the anti-segregation component is made from the following components in the indicated weight ratios: 50-60 parts of sulfonic acid monomer, 20-30 parts of acrylic acid compound, 10-20 parts of stabilizer, and 5-10 parts of initiator A.

[0009] Preferably, the sulfonic acid monomer is 2-methylpropanesulfonic acid; the acrylic compound may be selected from at least one of acrylic acid, acrylamide, acrylonitrile and acrylate; the stabilizer is a thiol substance, and is at least one of thiophenol, aminothiophenol, acetaminophen, hydroxythiophenol, cyclothioethane and dithiol.

[0010] Preferably, the initiator A comprises an oxidant and a reductant, forming a redox initiation system. The oxidant is at least one of persulfate, ammonium persulfate, and potassium persulfate, and the reductant is at least one of sodium bisulfite, ammonium hydroxide, and triethylamine. The molar ratio of the oxidant to the reductant is 2-4:1-2.

[0011] Preferably, the retarding component comprises the following components in parts by weight: 30-40 parts of unsaturated carboxylic acid monomers, 10-30 parts of unsaturated acid anhydrides, 20-40 parts of phosphate ester monomers, 0.6-1.5 parts of initiator B, and 10-12 parts of organophosphonic acid substances.

[0012] Preferably, the organophosphonic acid is selected from one or more of the following: hydroxyethylidene diphosphonic acid (HEDP), aminotrimethylenephosphonic acid (ATMP), 2-phosphono-1,2,4-tricarboxylate butane (PBTCA), polyaminopolyether methylenephosphonic acid (PAPEMP), 2-hydroxyphosphonoacetic acid (HPAA), ethylenediaminetetramethylenephosphonic acid (EDTMPS), and diethylenetriaminepentamethylenephosphonic acid (DTPMPA); and the initiator B is selected from one or more of the following: ammonium persulfate, sodium persulfate, hydrogen peroxide, benzoyl peroxide, or potassium persulfate.

[0013] Preferably, the filling carrier comprises the following components in parts by weight: 20-40 parts silica fume, 20-40 parts calcined kaolin, and 30-50 parts zeolite powder.

[0014] The present invention also provides a method for preparing a concrete waste slurry suspension stabilizer material, wherein a filler carrier is added to a solution of an anti-segregation component and a retarding component, and after being stirred evenly, the concrete waste slurry suspension stabilizer is obtained by spray drying.

[0015] Preferably, the anti-segregation component is prepared by polymerization of sulfonic acid monomers, acrylic compounds, stabilizers and initiator A, with the polymerization temperature being 90–120°C and the reaction time being 24–36 h.

[0016] Preferably, the method for preparing the retarding component includes the following steps:

[0017] S1. Dissolve unsaturated acid anhydride in deionized water to prepare solution I, purge with nitrogen for protection, and heat to 90°C; wherein the weight ratio of unsaturated acid anhydride to deionized water is 10-30:25-30.

[0018] S2. Prepare a solution by mixing unsaturated carboxylic acid monomers, phosphate ester monomers and deionized water to form solution II; wherein the weight ratio of unsaturated carboxylic acid monomers, phosphate ester monomers and 55-60 parts of deionized water is 30-40:20-40:55-60.

[0019] S3. After keeping solution I at a constant temperature for 30 minutes, start adding solution II dropwise, while simultaneously adding initiator B and organophosphonic acid. The dropwise addition time is 1 to 1.5 hours. After the dropwise addition is complete, cool down to 40°C and keep warm for 2 hours to end the reaction, thus obtaining the retarded component.

[0020] Therefore, the present invention, employing the above-mentioned concrete waste slurry suspension stabilizer material and its preparation method, possesses the following beneficial effects:

[0021] 1. This invention loads the anti-segregation component and retarding component obtained by polymerization onto inorganic powder materials. Since the inorganic powder materials have small particle size, they have a large contact area with water after being dispersed in the slurry. In application, this can improve the dissolution rate and dispersion effect of the polymer, and improve the efficiency of the effective functional components. At the same time, the addition of small-particle silica fume, calcined kaolin and other inorganic powder materials to the waste concrete slurry optimizes the gradation of suspended particles in the slurry and improves its anti-segregation performance.

[0022] 2. The 2-methylpropanesulfonic acid used in the anti-segregation component polymerization is highly reactive. As the main monomer, it can connect carboxylic acid, phosphoric acid, amide and other groups, and play the role of molecular skeleton. It also has good hydrolytic stability and acid and alkali resistance. The strong anionic sulfonic acid group (-SO3H) it contains makes it insensitive to acid, alkali and salt ions. It has strong stability in the high alkalinity environment of waste slurry. Moreover, its molecular chain is long and large. After polymerization, it can significantly enhance the steric hindrance effect of the polymer, improve the rigidity of the molecular chain and improve the stability of the performance.

[0023] 3. During the polymerization of the retarding component, unsaturated phosphonates are used as functional monomers grafted onto the carboxylic acid backbone. In the cement paste, they can gradually hydrolyze to release phosphonic acid groups with retarding effect, which have better water-reducing and dispersing effects than commonly used retarders. At the same time, the retarding component polymer prepared by this invention, as a polyelectrolyte, can chelate calcium ions in cement, thereby effectively delaying the cement hydration rate in waste paste and achieving a retarding effect.

[0024] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0025] To facilitate understanding of the present invention, the invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0026] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0027] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0028] The preparation method provided by this invention is used to prepare a suspension stabilizer suitable for waste concrete slurry. The specific steps are as follows:

[0029] S1: Preparation of filler powder material: First, put 35 parts of silica fume, 25 parts of calcined kaolin, and 40 parts of zeolite powder into the powder mixing kettle and stir for 5 minutes.

[0030] S2: Polymerization of the anti-segregation component: 50 parts of 2-methylpropanesulfonic acid monomer, 25 parts of acrylic acid, 15 parts of hydroxybenzylthiophenol, 7 parts of ammonium persulfate, and 3 parts of sodium bisulfite are mixed in a specific ratio, and 230 parts of deionized water are added. The polymerization temperature is controlled at 95℃. After the reaction time is 36 hours, it is allowed to cool naturally.

[0031] S3: Polymerization of the retarding component: Dissolve 20 parts of unsaturated acid anhydride in 25 parts of deionized water to prepare solution I, purge with nitrogen, and heat to 90℃; prepare solution B by mixing 35 parts of unsaturated carboxylic acid monomers, 35 parts of phosphate ester monomers, and 60 parts of deionized water; after keeping solution I at 90℃ for 30 min, start adding solution II dropwise, while adding 1 part of ammonium persulfate and 9 parts of hydroxyethylidene diphosphonic acid, controlling the dropwise addition time to 1 h; after the dropwise addition is completed, cool to 40℃ and keep warm for 2 h to end the reaction, thus obtaining the retarding component;

[0032] S4: Preparation of suspension stabilizer: After uniformly mixing the anti-segregation component and retarding component solutions formed by polymerization, add the mixed filler powder material. After stirring for 15 minutes, spray dry to obtain the concrete waste slurry suspension stabilizer of this invention.

[0033] S5: Application Effect: The prepared suspension stabilizer is added to the waste gas slurry generated by the concrete mixing plant at a ratio of 0.5% by mass. The waste slurry is then directly added to the existing concrete raw materials (the moisture content of the waste slurry needs to be calculated and included in the concrete mixing water volume). The concrete performance evaluation after application to C40 concrete is shown in Table 1.

[0034]

[0035] Therefore, the concrete waste slurry suspension stabilizer material and its preparation method prepared in this invention achieve homogenization and fixation of the concrete waste slurry components, and can maintain a long-term suspended stable state, solving the problem that waste slurry cannot be directly used for concrete preparation.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A concrete waste slurry suspension stabilizer material, characterized in that, The main functional components include the following components by weight percentage: 30-50% anti-segregation component, 20-30% retarding component, and 20-40% filler carrier. The anti-segregation component is made from the following components in the following weight ratios: 50-60 parts sulfonic acid monomer, 20-30 parts acrylic compound, 10-20 parts stabilizer, and 5-10 parts initiator A. The sulfonic acid monomer is 2-methylpropanesulfonic acid; the acrylic compound is selected from at least one of acrylic acid, acrylamide, acrylonitrile, and acrylates; the stabilizer is a thiol substance, specifically at least one of thiophenol, aminobenzylthiophenol, acetaminophen, hydroxybenzylthiophenol, and dithiol. The retarding component includes the following components by weight: 30-40 parts unsaturated carboxylic acid monomer, 10-30 parts unsaturated acid anhydride, 20-40 parts phosphate ester monomer, and 0.6-1.5 parts initiator B. The filling carrier comprises 10-12 parts of organophosphonic acid substances, and the following components by weight are: 20-40 parts silica fume, 20-40 parts calcined kaolin, and 30-50 parts zeolite powder. The preparation method of the concrete waste slurry suspension stabilizer material includes: adding the filler carrier to a pre-prepared mixed solution of anti-segregation component and retarding component, stirring evenly, and spray drying the resulting slurry to obtain the concrete waste slurry suspension stabilizer.

2. The concrete waste slurry suspension stabilizer material according to claim 1, characterized in that, The initiator A comprises an oxidant and a reductant, forming a redox initiation system. The oxidant is persulfate, and the reductant is at least one of sodium bisulfite, ammonium hydroxide, and triethylamine. The molar ratio of the oxidant to the reductant is 2-4:1-2.

3. The concrete waste slurry suspension stabilizer material according to claim 1, characterized in that, The organophosphonic acid is selected from one or more of the following: hydroxyethylidene diphosphonic acid (HEDP), aminotrimethylenephosphonic acid (ATMP), 2-phosphono-1,2,4-tricarboxylate butane (PBTCA), polyaminopolyether methylenephosphonic acid (PAPEMP), 2-hydroxyphosphonoacetic acid (HPAA), ethylenediaminetetramethylenephosphonic acid (EDTMPS), and diethylenetriaminepentamethylenephosphonic acid (DTPMPA); the initiator B is selected from one or more of the following: ammonium persulfate, sodium persulfate, hydrogen peroxide, benzoyl peroxide, or potassium persulfate.

4. The preparation method of a concrete waste slurry suspension stabilizer material according to claim 1, characterized in that, The anti-segregation component is prepared by polymerization of sulfonic acid monomers, acrylic compounds, stabilizers and initiator A. The polymerization temperature is 90~120℃ and the reaction time is 24~36 h.

5. The method for preparing a concrete waste slurry suspension stabilizer material according to claim 1, characterized in that, The preparation method of the retarding component includes the following steps: S1. Dissolve unsaturated acid anhydride in deionized water to prepare solution I, purge with nitrogen for protection, and heat to 90°C; wherein the weight ratio of unsaturated acid anhydride to deionized water is 10~30:25~30; S2. Prepare a solution by mixing unsaturated carboxylic acid monomers, phosphate ester monomers and deionized water to form solution II; wherein the weight ratio of unsaturated carboxylic acid monomers, phosphate ester monomers and deionized water is 30~40:20~40:55~60. S3. After keeping solution I at a constant temperature for 30 minutes, start adding solution II dropwise, while simultaneously adding initiator B and organophosphonic acid. The dropwise addition time is 1~1.5 hours. After the dropwise addition is complete, cool down to 40℃ and keep warm for 2 hours to end the reaction, and the retarded component can be obtained.

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