Method for controlling dosage of water reducing agent of recycled micro-powder-cement cementitious system

Abstract

This invention discloses a method for controlling the dosage of water-reducing agent in a recycled micro-powder-cement cementitious system, comprising: determining the dosage of recycled micro-powder in the recycled micro-powder-cement paste and the target fresh-mix performance index; detecting the phase components of the recycled micro-powder and the mass fraction of each phase component; establishing a calculation model for the competitive adsorption coefficient of water-reducing agent in the recycled micro-powder, and calculating the competitive adsorption coefficient of water-reducing agent in the recycled micro-powder; based on this, correcting the initial dosage of water-reducing agent using a piecewise function; preparing the recycled micro-powder-cement paste and measuring the actual fresh-mix performance to verify the final dosage of water-reducing agent. This invention achieves precise and rapid control of the water-reducing agent dosage by quantifying the competitive adsorption behavior of recycled micro-powder on the water-reducing agent. The target fresh-mix performance of the recycled micro-powder-cement paste can be obtained with a single control. This method is simple and easy to industrialize, promoting the efficient utilization of recycled micro-powder in cement-based materials.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a method for controlling the dosage of water-reducing agent in a recycled micro-powder cementitious system. Background Technology

[0002] With the advancement of urbanization, a large number of old buildings need to be demolished, generating a large amount of waste concrete. Waste concrete can be recycled into coarse and fine aggregates to achieve its resource utilization. This process will produce about 20%-30% recycled micro powder (RCP) with a particle size of less than 75μm.

[0003] Currently, recycled micro powder is widely used in the preparation of cement-based materials. However, the incorporation of recycled micro powder leads to problems such as poor workability and increased fluidity loss in fresh cement paste. When the amount of recycled micro powder is changed, there is no specific change pattern in the workability of fresh cement paste, making it difficult to accurately match the amount of water-reducing agent.

[0004] Currently, the dosage of water-reducing agents is mostly determined based on the dichotomy principle through empirical trial mixing. However, the mineral composition of recycled micro-powders is complex and variable, and the phase components with strong affinity for water-reducing agents will preferentially adsorb the agents. This leads to competitive adsorption of water-reducing agents between recycled micro-powders and cement. This competitive relationship results in problems such as numerous trial and error attempts, long adjustment times, and significant material waste in the empirical trial mixing method. It not only reduces the efficiency of accurately determining the dosage of water-reducing agents but also leads to unstable workability properties of fresh cement paste (such as fluidity, yield stress, and plastic viscosity).

[0005] Therefore, in order to solve the defects of low efficiency of empirical trial mixing and unstable slurry performance in the existing technology, it is necessary to provide a method for adjusting the dosage of water-reducing agent in recycled micro powder-cement cementitious system, so as to improve the performance stability of recycled micro powder-cement cementitious system and promote the efficient resource utilization of recycled micro powder. This is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a method for controlling the dosage of water-reducing agent in a recycled micro powder-cement cementitious system. By introducing a competitive adsorption coefficient to quantitatively control the dosage of water-reducing agent in recycled micro powder-cement paste in segments, the method achieves precise correction of the dosage of water-reducing agent, reduces the number of trial and error attempts, and improves the performance stability of fresh paste.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A method for controlling the dosage of water-reducing agent in a recycled micro-powder cementitious system includes the following steps:

[0009] (1) Determine the amount of recycled micro powder in the recycled micro powder-cement paste. and target fresh mixed performance indicators ;

[0010] (2) Obtaining the phase composition of the regenerated micro powder and the mass fractions of each phase component ;

[0011] (3) Calculate the competitive adsorption coefficient of the regenerated micro powder by establishing the following model or a weighted model that is physically equivalent to it. :

[0012] ;

[0013] in, The coefficient of competitive adsorption of recycled micropowder in the recycled micropowder-cement system; The various phase components in the regenerated micro powder The number of parts by weight; Phase composition The competitive adsorption coefficient.

[0014] (4) Adjustment of water-reducing agent dosage Based on the competitive adsorption coefficient The calculation is determined by the following formula:

[0015] ;

[0016] in, To ensure that the pure cement paste meets the target fresh mix specifications The amount of water-reducing agent added is called the initial dosage of water-reducing agent; This is the corrected dosage of water-reducing agent; The coefficient of competitive adsorption of recycled micropowder in the recycled micropowder-cement system; , To define the segmented boundaries of the competitive adsorption coefficient of recycled micropowder in the recycled micropowder-cement system, It is divided into three competition zones: low, medium, and high. , This is the water-reducing agent dosage compensation index for the corresponding interval, used to adjust the water-reducing agent dosage compensation range for each competition zone;

[0017] (5) Adjust the dosage of the water-reducing agent according to the above. Preparation of recycled micro powder-cement paste and measurement of actual fresh mix performance When | - | / When the dosage of water-reducing agent exceeds the preset value Δ, the dosage will be adjusted. The initial dosage of the water-reducing agent is considered to be subject to one iterative correction until | - | / The preset value Δ is met.

[0018] Preferably, in step (1), the fresh mixed performance indicators include, but are not limited to, the fluidity, yield stress, and plastic viscosity of the recycled micro powder-cement paste.

[0019] Preferably, in step (2), the phase composition of the recycled micro powder includes, but is not limited to, limestone component LSP, quartz component QZP and hardened cement paste component HPP.

[0020] Preferably, in step (3), the competitive adsorption coefficient of the regenerated micro powder is... Calculated based on the following formula:

[0021] ;

[0022] in, The coefficient of adsorption of recycled micro-powder in the recycled micro-powder-cement system is given. It is the mass fraction of limestone components in the recycled micro powder. It is the mass fraction of quartz component in the regenerated micro powder. It is the mass fraction of hardened cement paste components in recycled micro powder; It is the relative mass fraction of the limestone components. It is the relative mass fraction of the quartz component. It is the relative mass fraction of the components in the hardened cement paste; This refers to the dosage of water-reducing agent.

[0023] Preferably, in step (4), The value range is 1.0 to 1.3; The value range is 1.8 to 2.3; The value range is 0.45 to 0.65; The value range is 0.20 to 0.45.

[0024] Preferably, in step (5), the preset value Δ ranges from 5% to 8%.

[0025] Preferably, the water-reducing agent is a lignin sulfonate, naphthalene-based, or polycarboxylic acid-based agent.

[0026] Preferably, the limestone component in the recycled micro powder is derived from the coarse aggregate phase of the parent concrete; the quartz component is derived from the fine aggregate phase of the parent concrete; and the hardened cement paste component is derived from the hardened cement paste phase of the parent concrete.

[0027] Preferably, the relative mass fractions of the limestone component, quartz component, and hardened cement paste component are calculated based on the following formulas ①, ②, and ③, respectively:

[0028] ①

[0029] ②

[0030] ③

[0031] in, The amount of recycled micro powder in the recycled micro powder-cement cementitious system; This refers to the mass fraction of limestone components in the recycled micro powder. This refers to the mass fraction of the quartz component in the regenerated micro powder. This refers to the mass fraction of the hardened cement paste component in the recycled powder. This represents the relative mass fraction of limestone component in the recycled micronized powder-cement cementitious system. This represents the relative mass fraction of quartz component in the recycled micronized powder-cement cementitious system. This represents the relative mass fraction of hardened cement paste components in the recycled micro-powder-cement cementitious system.

[0032] Preferably, the mass fraction of the limestone component , quartz component mass parts Mass parts of hardened cement paste components satisfy + + =1; the amount of regenerated micro powder added The value range is (0,1); the component relative mass fraction The value range is (0%, 100%); the dosage of the water-reducing agent The range of values ​​is (0, +∞).

[0033] The present invention achieves the following technical effects compared to the prior art:

[0034] 1) This invention precisely compensates for the amount of ineffective water-reducing agent:

[0035] The competitive adsorption coefficient of regenerated micro powder A water-reducing agent dosage correction model was introduced to quantify the ineffective use of water-reducing agent caused by fluctuations in the mineral composition of recycled micro powder. This model accurately compensated for the distribution deviation of water-reducing agent caused by differences in the mineral composition of recycled micro powder, and significantly improved the stability of the fresh performance of recycled micro powder-cement paste.

[0036] 2) This invention improves adjustment efficiency and reduces material waste:

[0037] Compared with the traditional multi-round trial mixing and empirical adjustment method, this method only needs to detect the phase composition of recycled micro powder and calculate the competitive adsorption coefficient to quickly obtain the correct dosage of water-reducing agent. This reduces the number of trials and errors, shortens the adjustment time of recycled micro powder-slurry ratio, and reduces the waste of materials such as cement, recycled micro powder, and water-reducing agent, thereby reducing production costs.

[0038] 3) This invention promotes the efficient resource utilization of recycled micro powder:

[0039] This method can quickly stabilize the fluctuations in the fresh cement paste performance caused by the fluctuations in the mineral composition of recycled micro powder. It can be stably applied to cement cementitious systems with recycled micro powders of different sources and mineral compositions, thereby improving the resource utilization rate of construction waste and conforming to the industrial development trend of low-carbon and environmental protection.

[0040] 4) The method of this invention is simple and easy to apply industrially:

[0041] The calculation models of this method are mature and reliable, and the logic for correcting the water-reducing agent dosage is clear. It does not require complex equipment or professional technicians and can be directly applied to industrial production scenarios such as concrete mixing plants and cement product factories, and has broad application prospects. Attached Figure Description

[0042] Figure 1 This is an overall flowchart of the method for controlling the dosage of water-reducing agent in the recycled micro powder-cement cementitious system described in this invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] This invention discloses a method for controlling the dosage of water-reducing agent in a recycled micro-powder-cement cementitious system, comprising the following steps:

[0045] (1) Determine the amount of recycled micro powder in the recycled micro powder-cement paste. and target fresh mixed performance indicators ;

[0046] (2) Obtaining the phase composition of the regenerated micro powder and the mass fractions of each phase component ;

[0047] (3) Calculate the competitive adsorption coefficient of the regenerated micro powder by establishing the following model or a weighted model that is physically equivalent to it. :

[0048] ;

[0049] in, The coefficient of competitive adsorption of recycled micropowder in the recycled micropowder-cement system; The various phase components in the regenerated micro powder The number of parts by weight; Phase composition The competitive adsorption coefficient.

[0050] (4) Adjustment of water-reducing agent dosage Based on the competitive adsorption coefficient The calculation is determined by the following formula:

[0051] ;

[0052] in, To ensure that the pure cement paste meets the target fresh mix specifications The amount of water-reducing agent added is called the initial dosage of water-reducing agent; This is the corrected dosage of water-reducing agent; The coefficient of competitive adsorption of recycled micropowder in the recycled micropowder-cement system; , To define the segmented boundaries of the competitive adsorption coefficient of recycled micropowder in the recycled micropowder-cement system, It is divided into three competition zones: low, medium, and high. , This is the water-reducing agent dosage compensation index for the corresponding interval, used to adjust the water-reducing agent dosage compensation range for each competition zone;

[0053] (5) Adjust the dosage of the water-reducing agent according to the above. Preparation of recycled micro powder-cement paste and measurement of actual fresh mix performance When | - | / When the dosage of water-reducing agent exceeds the preset value Δ, the dosage will be adjusted. The initial dosage of the water-reducing agent is considered to be subject to one iterative correction until | - | / The preset value Δ is met.

[0054] In step (1), the fresh mixed performance indicators include, but are not limited to, the fluidity, yield stress, and plastic viscosity of the recycled micro powder-cement paste.

[0055] In step (2), the phase composition of the recycled micro powder includes, but is not limited to, limestone component LSP, quartz component QZP and hardened cement paste component HPP.

[0056] In step (3), the competitive adsorption coefficient of the regenerated micro powder Calculated based on the following formula:

[0057] ;

[0058] in, The coefficient of adsorption of recycled micro-powder in the recycled micro-powder-cement system is given. It is the mass fraction of limestone components in the recycled micro powder. It is the mass fraction of quartz component in the regenerated micro powder. It is the mass fraction of hardened cement paste components in recycled micro powder; It is the relative mass fraction of the limestone components. It is the relative mass fraction of the quartz component. It is the relative mass fraction of the components in the hardened cement paste; This refers to the dosage of water-reducing agent.

[0059] In step (4), The value range is 1.0 to 1.3; The value range is 1.8 to 2.3; The value range is 0.45 to 0.65; The value range is 0.20 to 0.45.

[0060] In step (5), the preset value Δ ranges from 5% to 8%.

[0061] Water-reducing agents are lignin sulfonate, naphthalene-based, and polycarboxylate-based.

[0062] The limestone component in the recycled micro powder originates from the coarse aggregate phase of the parent concrete; the quartz component originates from the fine aggregate phase of the parent concrete; and the hardened cement paste component originates from the hardened cement paste phase of the parent concrete.

[0063] The relative mass fractions of limestone, quartz, and hardened cement paste components are calculated based on the following formulas ①, ②, and ③, respectively:

[0064] ①

[0065] ②

[0066] ③

[0067] in, The amount of recycled micro powder in the recycled micro powder-cement cementitious system; This refers to the mass fraction of limestone components in the recycled micro powder. This refers to the mass fraction of the quartz component in the regenerated micro powder. This refers to the mass fraction of the hardened cement paste component in the recycled powder. This represents the relative mass fraction of limestone component in the recycled micronized powder-cement cementitious system. This represents the relative mass fraction of quartz component in the recycled micronized powder-cement cementitious system. This represents the relative mass fraction of hardened cement paste components in the recycled micro-powder-cement cementitious system.

[0068] mass fractions of limestone components , quartz component mass parts Mass parts of hardened cement paste components satisfy + + =1; Regenerated micro powder content The value range is (0,1); component relative mass fraction The value range is (0%, 100%); water-reducing agent dosage The range of values ​​is (0, +∞).

[0069] Example 1:

[0070] (1) Determination of slurry composition: The amount of recycled micro powder in recycled micro powder-cement slurry =0.3, target fresh mixed performance index Flowability 230mm, yield stress ≤2.5Pa.

[0071] The composition of the slurry is shown in Table 1 below:

[0072] Table 1: Composition of Recycled Micro Powder-Cement Paste

[0073] Slurry composition cement RCP water Mass (g) 700g 300g 500g

[0074] (2) Acquisition of phase composition of regenerated micro powder: The mass fractions of phase components of the regenerated micro powder were obtained by combined detection of XRD and thermal analysis: =0.35、 =0.25、 =0.40 (the rest are trace impurities, which are negligible).

[0075] (3) Calculation of competitive adsorption coefficient: First, pure cement slurry was prepared, and the initial dosage of water-reducing agent was measured to meet the target flowability of 230 mm. =1.75% (based on the total mass of cementitious materials). Calculated... =2.265.

[0076] (4) Correction of water-reducing agent dosage: due to =2.265≥ =2.0, substituting into the piecewise function iteration, we get =2.41%.

[0077] (5) Verification: Press =2.41% of recycled micro-powder was used to prepare cement paste. Actual fresh mix performance: fluidity 228mm, yield stress 2.45Pa; fluidity: | - | / =0.9%<Δ (Δ is taken as 5%), Yield stress: | - | / =2.0%<Δ (Δ is taken as 5%) meets the requirements, and the final water-reducing agent dosage is 2.41%.

[0078] Comparative Example 1:

[0079] (1) Determination of slurry composition: The amount of recycled micro powder in recycled micro powder-cement slurry =0.3, target fresh mixed performance index Flowability 230 mm, yield stress ≤ 2.5 Pa. The slurry composition is shown in Table 2 below:

[0080] Table 2: Composition of Recycled Micro Powder-Cement Paste

[0081] Slurry composition cement RCP water Mass (g) 700g 300g 500g

[0082] (2) Determine the initial First, pure cement slurry was prepared. The yield stress was measured to be ≤2.5 Pa when the target flowability of 230 mm was met. The initial dosage of the water-reducing agent was determined. =1.75% (based on the total mass of cementitious materials).

[0083] (3) Preparation of recycled micro powder-cement paste: Prepare recycled micro powder-cement paste according to Table 2, using the initial dosage of water-reducing agent. =1.75%, actual fresh mix performance: flowability 188mm, yield stress 3.1Pa, flowability: | - | / = 22.3%>Δ (Δ is taken as 5%), Yield stress: | - | / =19.4%>Δ (Δ is taken as 5%) does not meet the requirements, and the dosage of water-reducing agent needs to be adjusted.

[0084] (4) Adjust the dosage of water-reducing agent: Adjust the dosage of water-reducing agent to =2.00%, Actual fresh mix performance: Flowability 207mm, Yield stress 2.9Pa, Flowability: | - | / = 11.1%>Δ (Δ is taken as 5%), Yield stress: | - | / =13.8%>Δ (Δ is taken as 5%) does not meet the requirements, and the dosage of water-reducing agent needs to be adjusted.

[0085] (5) Adjust the dosage of water-reducing agent: Adjust the dosage of water-reducing agent to... =2.50%, actual fresh mix performance: flowability 249mm, yield stress 2.2Pa, flowability: | - | / =7.6%>Δ (Δ is taken as 5%), Yield stress: | - | / =13.6%>Δ (Δ is taken as 5%) does not meet the requirements, and the dosage of water-reducing agent needs to be adjusted.

[0086] (6) Adjust the dosage of water-reducing agent: Adjust the dosage of water-reducing agent to =2.40%, actual fresh mix performance: flowability 233mm, yield stress 2.4Pa, flowability: | - | / =1.3%<Δ (Δ is taken as 5%), yield stress: | - | / =4.2% < Δ (Δ is taken as 5%), which meets the requirements. The final determined dosage of water-reducing agent is 2.40%.

[0087] Example 2:

[0088] (1) Determination of slurry composition: The amount of recycled micro powder in recycled micro powder-cement slurry =0.45, target fresh mixed performance index Yield stress 2.0 Pa, plastic viscosity 0.5 Pa·s. The slurry composition is shown in Table 3 below:

[0089] Table 3: Composition of Recycled Micro Powder-Cement Paste

[0090] Slurry composition cement RCP water Mass (g) 550g 450g 500g

[0091] (2) Acquisition of phase composition of regenerated micro powder: The mass fractions of phase composition of the regenerated micro powder were obtained by combined XRD and thermal analysis: =0.60、 =0.20、 =0.20 (the rest are trace impurities, which are negligible).

[0092] (3) Calculation of competitive adsorption coefficient: First, pure cement paste was prepared, and the target yield stress of 2.0 Pa and plastic viscosity of 0.5 Pa·s were measured. The initial dosage of water-reducing agent was determined. =1.70% (based on the total mass of cementitious materials). Calculated... =1.768.

[0093] (4) Correction of water-reducing agent dosage: due to =1.3≤ =1.768≤ =1.8, substituting into the piecewise function iteration, we get =2.02%.

[0094] (5) Verification: Press =2.02% Recycled Micropowder-Cement Slurry was prepared. Actual fresh mix properties: Yield stress 2.1 Pa, Plastic viscosity 0.52 Pa·s; Yield stress: - | / =4.8% < Δ (Δ is taken as 8%), plastic viscosity: - | / =3.8%<Δ (Δ is taken as 8%), which meets the requirements, and the final water-reducing agent dosage is 2.02%.

[0095] Comparative Example 2:

[0096] (1) Determination of slurry composition: The amount of recycled micro powder in recycled micro powder-cement slurry =0.45, target fresh mixed performance index Yield stress 2.0 Pa, plastic viscosity 0.5 Pa·s. The slurry composition is shown in Table 4 below.

[0097] Table 4: Composition of Recycled Micro Powder-Cement Paste

[0098] Slurry composition cement RCP water Mass (g) 550g 450g 500g

[0099] (2) Determine the initial First, pure cement paste was prepared. The initial dosage of water-reducing agent was measured to meet the following conditions: yield stress of 2.0 Pa and plastic viscosity of 0.03 Pa·s. =1.70% (based on the total mass of cementitious materials).

[0100] (3) Preparation of recycled micro powder-cement paste: Prepare recycled micro powder-cement paste according to Table 4, using the initial dosage of water-reducing agent. =1.70%, actual fresh mix properties: yield stress 2.7 Pa, plastic viscosity 0.6 Pa·s, yield stress: | - | / = 25.9%>Δ (Δ is taken as 8%), Plastic viscosity: | - | / =16.7%>Δ (Δ is taken as 8%) does not meet the requirements, and the dosage of water-reducing agent needs to be adjusted.

[0101] (4) Adjust the dosage of water-reducing agent: Adjust the dosage of water-reducing agent to =2.20%, Actual fresh mix properties: Yield stress 1.68 Pa, Plastic viscosity 0.45 Pa·s, Yield stress: | - | / = 19.0%>Δ (Δ is taken as 8%), Plastic viscosity: | - | / =11.1%>Δ (Δ is taken as 8%) does not meet the requirements, and the dosage of water-reducing agent needs to be adjusted.

[0102] (5) Adjust the dosage of water-reducing agent: Adjust the dosage of water-reducing agent to... =2.00%, Actual fresh mix properties: Yield stress 2.1 Pa, Plastic viscosity 0.48 Pa·s, Yield stress: | - | / = 4.8% < Δ (Δ is taken as 8%), Plastic viscosity: | - | / =4.2% < Δ (Δ is taken as 8%), which meets the requirements. The final water-reducing agent dosage is 2.00%.

[0103] Example 3:

[0104] (1) Determination of slurry composition: The amount of recycled micro powder in recycled micro powder-cement slurry =0.20, target fresh mixed performance index Flowability 220 mm, yield stress ≤ 2.6 Pa. The slurry composition is shown in Table 5 below:

[0105] Table 5: Composition of Recycled Micro Powder-Cement Paste

[0106] Slurry composition cement RCP water Mass (g) 800g 200g 500g

[0107] (2) Acquisition of phase composition of regenerated micro powder: The mass fractions of phase composition of the regenerated micro powder were obtained by combined XRD and thermal analysis: =0.50、 =0.36、 =0.14 (the rest are trace impurities, which are negligible).

[0108] (3) Calculation of competitive adsorption coefficient: First, pure cement slurry was prepared, and the target flowability of 220 mm and yield stress ≤ 2.6 Pa were measured. The initial dosage of water-reducing agent was determined. =1.50% (based on the total mass of cementitious materials). Calculated... =1.660.

[0109] (4) Correction of water-reducing agent dosage: due to =1.3≤ =1.660≤ =1.8, substitute into the piecewise function iteration. The result is... =1.86%

[0110] (5) Verification: Press =1.86% recycled micro powder-cement paste was prepared, and the actual fresh mix performance was tested: target flowability 216mm, yield stress 2.5Pa; flowability: | - | / =1.9%<Δ (Δ is taken as 5%), Yield stress: | - | / =4.0% < Δ (Δ is taken as 5%) meets the requirements, and the final water-reducing agent dosage is 1.86%.

[0111] Comparative Example 3:

[0112] (1) Determination of slurry composition: The amount of recycled micro powder in recycled micro powder-cement slurry =0.20, target fresh mixed performance index Flowability 220 mm, yield stress ≤ 2.6 Pa. The slurry composition is shown in Table 6 below:

[0113] Table 6: Composition of Recycled Micro Powder-Cement Paste

[0114] Slurry composition cement RCP water Mass (g) 800g 200g 500g

[0115] (2) Determine the initial First, pure cement paste was prepared. When the target flowability of 220 mm was met, the yield stress was ≤2.6 Pa. The initial dosage of the water-reducing agent was... =1.50% (based on the total mass of cementitious materials).

[0116] (3) Preparation of recycled micro powder-cement paste: Prepare recycled micro powder-cement paste according to Table 6, using the initial dosage of water-reducing agent. =1.5%, actual fresh mix performance: flowability 160mm, yield stress 3.2Pa, flowability: | - | / = 37.5%>Δ (Δ is taken as 8%), Yield stress: | - | / =18.8%>Δ (Δ is taken as 8%) does not meet the requirements, and the dosage of water-reducing agent needs to be adjusted.

[0117] (4) Adjust the dosage of water-reducing agent: Adjust the dosage of water-reducing agent to =2.00%, Actual fresh mix performance: Flowability 260mm, Yield stress 2.3Pa, Flowability: | - | / = 15.4%>Δ (Δ is taken as 8%), Yield stress: | - | / =13.0%>Δ (Δ is taken as 8%) does not meet the requirements, and the dosage of water-reducing agent needs to be adjusted.

[0118] (5) Adjust the dosage of water-reducing agent: Adjust the dosage of water-reducing agent to... =1.80%, Actual fresh mix performance: Flowability 200mm, Yield stress 2.8Pa, Flowability: | - | / =10.0%>Δ (Δ is taken as 8%) does not meet the requirements, yield stress: | - | / =7.1% <Δ (Δ is taken as 8%), the dosage of water-reducing agent needs to be adjusted.

[0119] (6) Adjust the dosage of water-reducing agent: Adjust the dosage of water-reducing agent to =1.85%, Actual fresh mix performance: Flowability 223mm, Yield stress 2.5Pa, Flowability: | - | / =1.3%<Δ (Δ is taken as 5%), yield stress: | - | / =4.0% < Δ (Δ is taken as 5%), which meets the requirements. The final dosage of water-reducing agent is determined to be 1.85%.

[0120] Comparative experiment:

[0121] The water-reducing agent dosage was compared and adjusted in the recycled micro-powder-cement cementitious systems of Examples 1, 2, and 3. The results of the empirical mixing method and the method of the present invention are shown in Table 7 below:

[0122] Table 7: Comparison of water-reducing agent dosage control in recycled micro-powder-cement cementitious systems in the examples and comparative examples

[0123] Adjustment method Flowability (Δ) Yield stress (Δ) Plastic viscosity (Δ) Number of trial mixing Example 1 0.9% 2.0% / 1 time Comparative Example 1 1.3% 4.2% / 4 times Example 2 / 4.8% 3.8% 1 time Comparative Example 2 / 4.8% 4.2% 3 times Example 3 1.9% 4.0% / 1 time Comparative Example 3 1.3% 4.0% / 4 times

[0124] The comparison results show that, compared with the empirical trial mixing method, the method of the present invention significantly reduces the number of trial mixing times, shortens the adjustment time, and results in smaller deviations in the final slurry performance and higher stability, fully demonstrating the superiority of the present invention.

[0125] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for controlling the dosage of water-reducing agent in a recycled micro-powder-cement cementitious system, characterized in that, Includes the following steps: (1) Determine the amount of recycled micro powder in the recycled micro powder-cement paste. and target fresh mixed performance indicators ; (2) Obtaining the phase composition of the regenerated micro powder and the mass fractions of each phase component ; (3) Calculate the competitive adsorption coefficient of the regenerated micro powder by establishing the following model or a weighted model that is physically equivalent to it. : ； in, The coefficient of competitive adsorption of recycled micropowder in the recycled micropowder-cement system; The various phase components in the regenerated micro powder Number of parts by mass; Phase composition The competitive adsorption coefficient. (4) Adjustment of water-reducing agent dosage Based on the competitive adsorption coefficient The calculation is determined by the following formula: ； in, To ensure that the pure cement paste meets the target fresh mix specifications The amount of water-reducing agent added is called the initial dosage of water-reducing agent; This is the corrected dosage of water-reducing agent; The coefficient of competitive adsorption of recycled micropowder in the recycled micropowder-cement system; , To define the segmented boundaries of the competitive adsorption coefficient of recycled micropowder in the recycled micropowder-cement system, It is divided into three competition zones: low, medium, and high. , This is the water-reducing agent dosage compensation index for the corresponding interval, used to adjust the water-reducing agent dosage compensation range for each competition zone; (5) Adjust the dosage of the water-reducing agent according to the above. Preparation of recycled micro powder-cement paste and measurement of actual fresh mix performance When | - | / When the dosage of water-reducing agent exceeds the preset value Δ, the dosage will be adjusted. The initial dosage of the water-reducing agent is considered to be subject to one iterative correction until | - | / The preset value Δ is met.

2. The method for controlling the dosage of water-reducing agent in a recycled micro-powder-cement cementitious system according to claim 1, characterized in that, In step (1), the fresh mixed performance indicators include, but are not limited to, the fluidity, yield stress, and plastic viscosity of the recycled micro powder-cement paste.

3. The method for controlling the dosage of water-reducing agent in a recycled micro-powder-cement cementitious system according to claim 1, characterized in that, In step (2), the composition of the recycled micro powder phase includes, but is not limited to, limestone component LSP, quartz component QZP and hardened cement paste component HPP.

4. The method for controlling the dosage of water-reducing agent in a recycled micro-powder-cement cementitious system according to claim 1, characterized in that, In step (3), the competitive adsorption coefficient of the regenerated micro powder Calculated based on the following formula: ； in, The coefficient of adsorption of recycled micro-powder in the recycled micro-powder-cement system is given. It is the mass fraction of limestone components in the recycled micro powder. It is the mass fraction of quartz component in the regenerated micro powder. It is the mass fraction of hardened cement paste components in recycled micro powder; It is the relative mass fraction of the limestone components. It is the relative mass fraction of the quartz component. It is the relative mass fraction of the components in the hardened cement paste; This refers to the dosage of water-reducing agent.

5. The method for controlling the dosage of water-reducing agent in a recycled micro-powder-cement cementitious system according to claim 1, characterized in that, In step (4), The value range is 1.0 to 1.3; The value range is 1.8 to 2.3; The value range is 0.45 to 0.65; The value range is 0.20 to 0.

45.

6. The method for controlling the dosage of water-reducing agent in a recycled micro-powder-cement cementitious system according to claim 1, characterized in that, In step (5), the preset value Δ ranges from 5% to 8%.

7. The method for controlling the dosage of water-reducing agent in a recycled micro-powder-cement cementitious system according to claim 1, characterized in that, The water-reducing agent is a lignin sulfonate, naphthalene-based, or polycarboxylic acid-based agent.

8. The method for controlling the dosage of water-reducing agent in a recycled micro-powder-cement cementitious system according to claim 3, characterized in that, The limestone component in the recycled micro powder originates from the coarse aggregate phase of the parent concrete; the quartz component originates from the fine aggregate phase of the parent concrete; and the hardened cement paste component originates from the hardened cement paste phase of the parent concrete.

9. The method for controlling the dosage of water-reducing agent in a recycled micro-powder-cement cementitious system according to claim 4, characterized in that, The relative mass fractions of the limestone component, quartz component, and hardened cement paste component are calculated based on the following formulas ①, ②, and ③, respectively: ① ② ③ in, The amount of recycled micro powder in the recycled micro powder-cement cementitious system; This refers to the mass fraction of limestone components in the recycled micro powder. This refers to the mass fraction of the quartz component in the regenerated micro powder. This refers to the mass fraction of the hardened cement paste component in the recycled powder. This represents the relative mass fraction of limestone component in the recycled micronized powder-cement cementitious system. This represents the relative mass fraction of quartz component in the recycled micronized powder-cement cementitious system. This represents the relative mass fraction of hardened cement paste components in the recycled micro-powder-cement cementitious system.

10. A method for controlling the dosage of water-reducing agent in a recycled micro-powder-cement cementitious system according to any one of claims 1 to 12, characterized in that, The mass fraction of the limestone component , quartz component mass parts Mass parts of hardened cement paste components satisfy + + =1; the amount of regenerated micro powder added The value range is (0,1); the component relative mass fraction The value range is (0%, 100%); the dosage of the water-reducing agent The range of values ​​is (0, +∞).

Images