Detection Method for Residual Concentration of Polyaluminium Chloride and Content of Active Ingredients in Manufactured Sand

Abstract

The present invention discloses a method for detecting the concentration and effective ingredient content of residual polyaluminium chloride in machine-made sand, comprising: establishing a database of double threshold values of polyaluminium chloride standard aqueous solutions under conditions of different concentrations and different effective ingredient contents based on the S-V relationship curve of a standard sample, and fitting the database of double threshold values of polyaluminium chloride standard aqueous solutions into a nonlinear surface formula; obtaining characteristic points V1 and V2 from the S-V relationship curve of the sample to be tested, substituting V1 and V2 into the nonlinear surface formula fitted by the database of double threshold values of polyaluminium chloride standard aqueous solutions, and obtaining the concentration Φ and effective ingredient content Al of the sample to be tested by solving a set of nonlinear equations; and calculating the concentration Φ0 of polyaluminium chloride attached to the machine-made sand based on the mass ratio of machine-made sand to deionized water. The present invention effectively solves the current limitation of the lack of known effective ingredient content of polyaluminium chloride in the field of machine-made sand detection.

Description

Technical Field

[0001] The present disclosure relates to the technical field of civil engineering materials, and more particularly to a method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand. Background Art

[0002] Natural river sand or artificial sand is one of the most important raw materials for concrete. In recent years, river sand resources have been declining, and manufactured sand has been widely used in bridge and road engineering due to its regular shape and excellent mechanical properties. However, the production process of manufactured sand produces a large amount of stone and mud powder, which is difficult to remove with simple screening processes and requires mineral washing operations. To control costs, manufactured sand manufacturers generally pursue non-standard and high-efficiency washing processes. Polyaluminum chloride is often used as a flocculant to accelerate the sedimentation of mud and stone powder. This will result in the attachment of polyaluminum chloride with an unknown amount of active ingredients to the manufactured sand, which actually changes the properties of the manufactured sand, which in turn has a significant impact on the performance of concrete and leads to poor quality of concrete projects.

[0003] The study clearly shows that when polyaluminium chloride is attached to machine-made sand, it will significantly affect the slump and slump loss of concrete. Specifically, for polyaluminium chloride with an active ingredient content of 26%, for every 0.01% increase in the amount of polyaluminium chloride attached to the machine-made sand, the mortar expansion is reduced by about 10 mm. When the polyaluminium chloride attached to the machine-made sand reaches 0.03% of the mass of the machine-made sand, the mortar expansion can be reduced by more than 25%. At the same time, polyaluminium chloride has different characteristics of different active ingredient contents. Polyaluminium chloride with a larger active ingredient content has a better flocculation effect. Therefore, when using polyaluminium chloride with an active ingredient content of 30% for testing, the above two thresholds can be reduced to 0.005% and 0.015%, respectively.

[0004] Existing tests for polyaluminium chloride (PAC) are not yet capable of detecting PAC with an unknown active ingredient content attached to manufactured sand. Furthermore, manufactured sand also contains other interfering impurities, such as fine mud particles and pigment particles that cause the sand washing water to appear yellowish-brown. In fact, the engineering community has very strict regulations on the fluidity of concrete under certain mix ratios, which determines whether fresh concrete can be successfully pumped and poured. Testing PAC only for a specific active ingredient content is of limited significance. A method is needed that can simultaneously detect both the concentration of PAC attached to manufactured sand and the active ingredient content, thereby enabling a more comprehensive assessment of manufactured sand performance and ensuring that the concrete fluidity meets on-site requirements.

[0005] Therefore, a fast, low-cost and accurate method for detecting different concentrations and effective ingredient contents of polyaluminium chloride in machine-made sand is needed. Summary of the Invention

[0006] (1) Technical issues to be resolved

[0007] In view of this, the present disclosure provides a method for detecting the concentration and effective component content of residual polyaluminium chloride in machine-made sand, so as to solve the limitation problem of the lack of the effective component content of polyaluminium chloride in the current machine-made sand detection field.

[0008] (2) Technical solution

[0009] The present disclosure provides a method for detecting the concentration of residual polyaluminium chloride and the content of effective components in machine-made sand, the method comprising:

[0010] S1: Prepare samples to be tested, standard samples and detection reagents;

[0011] S2: Connect detection components and configure detection equipment;

[0012] S3: Testing the standard sample to obtain the SV relationship curve between the conductivity S output by the conductivity meter of the standard sample and the volume V of the added polyaluminium chloride standard aqueous solution;

[0013] S4: establishing a double-threshold database of polyaluminium chloride standard aqueous solutions under conditions of different concentrations and different active ingredient contents based on the SV relationship curve of the standard sample, and fitting the double-threshold database of the polyaluminium chloride standard aqueous solution into a nonlinear surface formula;

[0014] S5: Testing the sample to be tested, and obtaining an SV relationship curve between the conductivity S output by the conductivity meter of the sample to be tested and the volume V of the sample to be tested;

[0015] S6: Obtain characteristic points V1 and V2 from the SV relationship curve of the sample to be tested, substitute V1 and V2 into the nonlinear surface formula fitted by the double threshold database of polyaluminum chloride standard aqueous solution, and obtain the concentration Φ and active ingredient content Al of the polyaluminum chloride in the sample to be tested by solving the nonlinear equation group;

[0016] S7: Based on the mass ratio of machine-made sand to deionized water, the concentration of polyaluminium chloride attached to the machine-made sand is calculated to obtain Φ0.

[0017] In the above solution, step S1 includes:

[0018] S11: Fully mix the machine-made sand sample to be tested and deionized water in a mass ratio of 1:1 to 1:3 to prepare the sample to be tested;

[0019] S12: Prepare polyaluminium chloride solid samples with different active ingredient contents, ranging from 26% to 30% in steps of 2%; prepare polyaluminium chloride standard aqueous solutions with concentrations of 0.004% to 0.016% using deionized water as standard samples;

[0020] S13: Prepare Class A and Class B reagents as detection reagents, wherein the Class A reagent can react with polyaluminum chloride and has a relatively obvious reaction phenomenon, and the Class B reagent does not react with polyaluminum chloride but has good conductivity.

[0021] In the above scheme, the Class A reagent in step S13 includes: copper sulfate, copper chloride, ferric chloride, potassium chloride, ferrous chloride, nickel chloride, potassium chromate, potassium dichromate or potassium permanganate; the concentration of the Class A reagent is 0.002 mol / L~0.005 mol / L; the Class B reagent in step S13 includes: sodium sulfate, potassium sulfate, magnesium sulfate, ferric sulfate or ferrous sulfate; the concentration of the Class B reagent is 0.001 mol / L~0.003 mol / L.

[0022] In the above solution, step S2 includes:

[0023] S21: Connect the solution pools numbered 1 and 2 in series with copper wires, connect the positive electrode of solution pool No. 1 to the negative electrode of solution pool No. 4, and then connect them to the positive and negative electrodes of the conductivity meter; use hoses to connect solution pools No. 1 and 2 to solution pool No. 3, set up a peristaltic pump in the middle, and adjust the peristaltic pump flow rate to 2-5 ml / min;

[0024] S22: Prepare a 4-channel synchronous electromagnetic stirrer with a rotation speed of 100 rpm to 500 rpm.

[0025] In the above solution, step S3 includes:

[0026] S31: Take 200mL~300mL of Class A reagent and inject it into the No. 1 solution tank of the detection equipment, and take another portion of the same volume of Class B reagent and inject it into the No. 2 solution tank of the detection equipment; take 500mL~1000mL of standard sample and add it into the No. 3 solution tank;

[0027] S32: Turn on the power supply, and the single chip microcomputer immediately records the initial conductivity output conductivity S0; turn on the peristaltic pump, and add the polyaluminium chloride standard aqueous solution in the No. 3 solution tank to the No. 1 and No. 2 solution tanks. After each addition of 5ml~10ml, record the conductivity meter output conductivity S x ;Conductivity S0 and S x Normalize it:

[0028] S=S x -S0

[0029] The SV relationship curve between the conductivity S output by the conductivity meter and the volume V of the added polyaluminium chloride standard aqueous solution was drawn using a single chip microcomputer, with the starting point being point 0.

[0030] In the above solution, step S4 includes:

[0031] S41: For each polyaluminium chloride standard aqueous solution with different concentrations of active ingredient content, obtain the range of characteristic points on the curve under conditions of different concentrations and different active ingredient contents, record them as dual thresholds represented by the volume V of the added polyaluminium chloride standard aqueous solution, and establish a database of dual thresholds of polyaluminium chloride standard aqueous solutions under conditions of different concentrations and different active ingredient contents;

[0032] S42: Fitting the double-threshold database of the polyaluminium chloride standard aqueous solution into a nonlinear surface formula.

[0033] In the above scheme, in the dual threshold value represented by the volume V of the added polyaluminum chloride standard aqueous solution in step S41, threshold 1 corresponds to the maximum value of the conductivity S on the curve, which is the corresponding volume V1 of the polyaluminum chloride standard aqueous solution, and threshold 2 corresponds to the intersection of the curve and the x-axis, which is the corresponding volume V2 of the polyaluminum chloride standard aqueous solution;

[0034] The nonlinear surface formula for fitting the database of the double threshold value of the polyaluminium chloride standard aqueous solution in step S42 is as follows:

[0035]

[0036]

[0037] Among them, the horizontal axis x and the vertical axis y correspond to the concentration Φ and the effective ingredient content Al of the polyaluminum chloride standard sample respectively. Except for V1, V2, Φ and Al, other parameters are constant coefficients.

[0038] In the above solution, step S5 includes:

[0039] S51: Take 200mL~300mL of Class A reagent and inject it into the No. 1 solution tank of the detection equipment, take an equal volume of Class B reagent and inject it into the No. 2 solution tank of the detection equipment; take 500mL~1000mL of the sample to be tested and add it into the No. 3 solution tank;

[0040] S52: Turn on the power supply, and the single chip computer immediately records the initial output conductivity S0 of the conductivity meter; turn on the peristaltic pump, and add the sample to be tested in the No. 3 solution pool to the No. 1 and No. 2 solution pools. After each 5ml~10ml is added, the conductivity S output by the conductivity meter is recorded. x ;Conductivity S0 and S x Normalize it:

[0041] S=S x - S0

[0042] The SV relationship curve between the conductivity S output by the conductivity meter and the volume V of the sample to be tested is drawn using a single-chip microcomputer, with the starting point being point 0.

[0043] In the above solution, the characteristic point V1 in step S6 is the volume V1 of the sample to be detected, corresponding to the maximum value of the conductivity S; the characteristic point V2 in step S6 is the volume V2 of the sample to be detected, corresponding to the intersection of the curve and the x-axis.

[0044] In the above scheme, the concentration of polyaluminium chloride attached to the machine-made sand is calculated in step S7 using the following calculation method:

[0045] Φ0=Φ×m2 / m1

[0046] Wherein, m1 is the mass of machine-made sand in step S1, and m2 is the mass of deionized water in step S1.

[0047] In the above scheme, the method further includes: judging whether the machine-made sand raw material from which the machine-made sand sample is obtained can be used for concrete preparation based on the calculated concentration Φ0 of polyaluminium chloride attached to the machine-made sand and the effective component content Al of polyaluminium chloride, wherein:

[0048] When the test result shows that the effective component content of polyaluminium chloride is 26%, when the concentration of polyaluminium chloride Φ0≤0.01%, its effect on the slump and slump loss of concrete is small, and it can be used to prepare concrete; when the concentration of polyaluminium chloride is 0.01%<Φ0≤0.03%, its effect on the slump and slump loss of concrete is significant, and the concrete mix ratio needs to be adjusted, and the amount of water reducer needs to be appropriately increased to meet the slump requirements; when the concentration of polyaluminium chloride Φ0>0.03%, its effect on the slump and slump loss of concrete can no longer be compensated by water reducer, and the machine-made sand needs to be washed twice with clean water before retesting;

[0049] When the test result shows that the effective ingredient content of polyaluminium chloride is 30%, when the concentration of polyaluminium chloride Φ0≤0.005%, its effect on the slump and slump loss of concrete is small, and it can be used to prepare concrete; when the concentration of polyaluminium chloride is 0.005%<Φ0≤0.015%, its effect on the slump and slump loss of concrete is significant, and the concrete mix ratio needs to be adjusted, and the amount of water reducer needs to be appropriately increased to meet the slump requirements; when the concentration of polyaluminium chloride Φ0>0.015%, its effect on the slump and slump loss of concrete can no longer be compensated by water reducer, and the machine-made sand needs to be cleaned twice with clean water before retesting.

[0050] (3) Beneficial effects

[0051] It can be seen from the above technical solution that the method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand provided by the present disclosure has at least the following beneficial effects:

[0052] 1. The present disclosure provides a method for detecting the concentration and effective ingredient content of residual polyaluminium chloride in manufactured sand. Through a one-time detection method, the effective ingredient content of the polyaluminium chloride flocculant attached to the manufactured sand and the corresponding concentration value are directly, quickly, and accurately tested. This effectively solves the current limitation of the lack of known effective ingredient content of polyaluminium chloride in the field of manufactured sand detection, and ensures a reasonable assessment of the quality of the manufactured sand. This has not been mentioned in the prior art, and is also the biggest difference and the most important innovation of the present disclosure from the prior art. This is because the prior art mostly uses a concentration test or characterization method for a certain polyaluminium chloride flocculant (existing turbidity method, absorbance method, etc.). This is not conducive to detecting the concentration of flocculants with multiple effective ingredient contents. It will result in a higher measured concentration of a flocculant with a lower effective ingredient content or a lower measured concentration of a flocculant with a higher effective ingredient content, which is not conducive to a reasonable assessment of the quality of the manufactured sand.

[0053] 2. The method for detecting the concentration and effective ingredient content of residual polyaluminum chloride in machine-made sand provided by the present disclosure fully considers soluble impurities other than polyaluminum chloride flocculants attached to the machine-made sand and fine particles that change the color of the aqueous solution. It adopts AC conductivity and compensation testing methods to avoid the interference of the above impurities on the test results. This expands the detection of polyaluminum chloride aqueous solutions to the detection of the concentration of flocculants attached to the machine-made sand. This is completely different from the existing technology and also solves the problems that have not been solved by the existing technology (existing turbidity method, absorbance method, etc.), highlighting the innovativeness of the present disclosure.

[0054] 3. The present invention provides a method for detecting the concentration and effective ingredient content of residual polyaluminium chloride in machine-made sand. By establishing a dual threshold value and a dual threshold value database for the conductivity S-dropping volume V curve of a standard aqueous solution of polyaluminium chloride, the method can determine the effective ingredient content and concentration of polyaluminium chloride. Compared with the existing technology that only uses a single slope and a single inflection point, the method is more accurate and can accurately determine the amount of polyaluminium chloride attached to machine-made sand with different effective ingredient contents at the same concentration. The operation method is simple and has strong universality, and can simply and effectively determine the quality of machine-made sand.

[0055] 4. The present disclosure provides a method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in manufactured sand, and establishes a complete set of evaluation methods and post-treatment methods for polyaluminium chloride flocculants attached to manufactured sand that affect the workability of concrete. This can prompt on-site staff to pay timely attention to questionable manufactured sand raw materials, and assist technical personnel in making adjustments to the concrete mix ratio to ensure the quality of concrete projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The above contents and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0057] Figure 1 The present invention is a flowchart of a method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand according to an embodiment of the present invention.

[0058] Figure 2a and Figure 2b This is a dual threshold database of polyaluminium chloride standard aqueous solutions with a concentration of 0.004% to 0.016% and an active ingredient content of 26% to 30% according to the embodiment of the present disclosure; wherein the abscissa x and the ordinate y correspond to the concentration Φ and the active ingredient content Al of the polyaluminium chloride standard sample, respectively. Figure 2a The z axis in the middle is the volume V1 of the sample to be tested. Figure 2b The middle z-axis is the volume V2 of the sample to be tested;

[0059] Figure 3 is the SV curve obtained by testing sample 1 according to an embodiment of the present disclosure;

[0060] Figure 4 is the SV curve obtained by testing sample 2 according to an embodiment of the present disclosure;

[0061] Figure 5 SV curve obtained by testing sample 3 according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0062] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0063] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0064] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0065] To address the current difficulty in quantitatively detecting the residual amount of polyaluminium chloride (PAC) in machine-made sand containing varying amounts of active ingredients and unknown concentrations, while also preventing the impact of soluble impurities and colored particles attached to the machine-made sand that alter water quality on the test results, the present disclosure proposes a method for detecting the concentration and active ingredient content of residual PAC in machine-made sand. This method directly, rapidly, and accurately measures the active ingredient content and corresponding concentration of PAC attached to the machine-made sand, ensuring a reasonable assessment of the quality of the machine-made sand. This approach, which has not been addressed in the prior art, highlights the innovation of the present disclosure. Furthermore, the present disclosure fully considers soluble impurities other than the PAC flocculant attached to the machine-made sand and fine particles that alter the color of the aqueous solution, avoiding interference with the test results from these impurities, a significant difference from the prior art. Furthermore, the present disclosure establishes a dual threshold value and a dual threshold database for the SV curve (i.e., the conductivity S-drop volume V curve) of a standard aqueous solution of PAC to determine the active ingredient content and concentration. Furthermore, an evaluation method and post-treatment method for PAC attached to machine-made sand are provided to ensure the quality of concrete projects.

[0066] like Figure 1 As shown, Figure 1 A flow chart of a method for detecting the concentration and effective component content of residual polyaluminium chloride in machine-made sand according to an embodiment of the present disclosure is shown. The method comprises the following steps:

[0067] S1: Prepare samples to be tested, standard samples and test reagents; specifically include:

[0068] S11: Fully mix the machine-made sand sample to be tested and deionized water in a mass ratio of 1:1 to 1:3 to ensure that the polyaluminum chloride flocculant molecules attached to the machine-made sand sample can be fully dissolved in the water, thereby obtaining a polyaluminum chloride flocculant aqueous solution containing an unknown amount of active ingredients as the sample to be tested;

[0069] S12: Prepare solid polyaluminium chloride samples with varying active ingredient contents, ranging from 26% to 30% in 2% increments. Prepare standard polyaluminium chloride aqueous solutions with concentrations ranging from 0.004% to 0.016% using deionized water as standard samples.

[0070] S13: preparing type A and type B reagents as detection reagents, wherein the type A reagent can react with the polyaluminum chloride flocculant and has a relatively obvious reaction phenomenon, and the type B reagent does not react with the polyaluminum chloride flocculant but has good conductivity;

[0071] In this step, the Class A reagent includes: copper sulfate, copper chloride, ferric chloride, potassium chloride, ferrous chloride, nickel chloride, potassium chromate, potassium dichromate or potassium permanganate, etc. The Class A reagent can react with the polyaluminum chloride flocculant and has a relatively obvious reaction phenomenon. The concentration of the Class A reagent is 0.002 mol / L to 0.005 mol / L. Under this concentration condition, when the concentration of the polyaluminum chloride flocculant in the sample to be tested is extremely low, the two are conducive to rapid reaction.

[0072] In this step, the Class B reagent includes: sodium sulfate, potassium sulfate, magnesium sulfate, ferric sulfate or ferrous sulfate, etc. This type of reagent does not react with the polyaluminum chloride flocculant but has good conductivity; the concentration of the Class B reagent is 0.001 mol / L~0.003 mol / L. Under this concentration condition, when the concentration of the polyaluminum chloride flocculant in the sample to be tested is extremely low, it can ensure that the polyaluminum chloride flocculant component has good conductivity.

[0073] S2: Connect the detection components and configure the detection equipment; specifically including:

[0074] S21: Connect the solution pools numbered 1 and 2 in series with copper wires, connect the positive electrode of solution pool No. 1 to the negative electrode of solution pool No. 4, and then connect them to the positive and negative electrodes of the conductivity meter; use hoses to connect solution pools No. 1 and 2 to solution pool No. 3, set up a peristaltic pump in the middle, and adjust the peristaltic pump flow rate to 2-5 ml / min. This speed can ensure that the polyaluminium chloride flocculant reacts fully with the Class A reagent and also ensure stable conductivity meter output;

[0075] S22: Prepare a 4-channel synchronous electromagnetic stirrer with a rotation speed of 100r / min~500r / min to accelerate the full reaction of polyaluminum chloride flocculant and Class A reagent, and also avoid the influence of irregular molecular thermal motion in the solution on conductivity, ensuring stable current output; the reason for using this circuit structure to carry out the test is that it can shield the soluble impurities (including soluble salts, mud powder, stone powder, etc.) attached to the machine-made sand from interfering with the test results, thereby showing the difference from the existing technology.

[0076] S3: Testing the standard sample to obtain the SV relationship curve between the conductivity S output by the conductivity meter of the standard sample and the volume V of the added polyaluminium chloride standard aqueous solution; specifically including:

[0077] S31: Take 200mL~300mL of Class A reagent and inject it into the No. 1 solution tank of the detection equipment, and take another portion of the same volume of Class B reagent and inject it into the No. 2 solution tank of the detection equipment; take 500mL~1000mL of standard sample and add it into the No. 3 solution tank;

[0078] S32: Turn on the power supply, and the single chip microcomputer immediately records the initial conductivity output conductivity S0; turn on the peristaltic pump, and add the polyaluminium chloride standard aqueous solution in the No. 3 solution tank to the No. 1 and No. 2 solution tanks. After each addition of 5ml~10ml, record the conductivity meter output conductivity S x ;Conductivity S0 and S x Normalize it:

[0079] S=S x -S0

[0080] The SV relationship curve between the conductivity S output by the conductivity meter and the volume V of the added polyaluminium chloride standard aqueous solution was drawn using a single chip microcomputer, with the starting point being point 0.

[0081] S4: establishing a database of double threshold values of polyaluminium chloride standard aqueous solutions under conditions of different concentrations and different active ingredient contents based on the SV relationship curve of the standard sample, and fitting the database of double threshold values of polyaluminium chloride standard aqueous solutions into a nonlinear surface formula; specifically comprising:

[0082] S41: For each polyaluminium chloride standard aqueous solution with different concentrations of active ingredient content, obtain the range of characteristic points on the curve under conditions of different concentrations and different active ingredient contents, record them as dual thresholds represented by the volume V of the added polyaluminium chloride standard aqueous solution, and establish a database of dual thresholds of polyaluminium chloride standard aqueous solutions under conditions of different concentrations and different active ingredient contents;

[0083] In this step, in the dual threshold represented by the volume V of the added polyaluminum chloride standard aqueous solution, the maximum value of the conductivity S on the curve corresponding to threshold 1 is the corresponding volume V1 of the polyaluminum chloride standard aqueous solution, and the volume V2 of the polyaluminum chloride standard aqueous solution corresponding to the intersection of the curve and the x-axis is corresponding to threshold 2;

[0084] S42: fitting the double-threshold database of the polyaluminium chloride standard aqueous solution into a nonlinear surface formula;

[0085] In this step, the database of the double threshold value of the polyaluminium chloride standard aqueous solution (such as Figure 2a 、 Figure 2b ) The nonlinear surface formula for fitting is as follows:

[0086]

[0087]

[0088] Among them, the horizontal axis x and the vertical axis y correspond to the concentration Φ and the effective ingredient content Al of the polyaluminium chloride standard sample respectively. Figure 2a The z axis in the middle is the volume V1 of the sample to be tested. Figure 2b The z-axis is the volume V2 of the sample to be tested. Except for V1, V2, Φ and Al, other parameters are constant coefficients. The constant coefficient fitting results and fitting goodness are shown in the following table:

[0089]

[0090] S5: Testing the sample to be tested to obtain a SV relationship curve between the conductivity S output by the conductivity meter of the sample to be tested and the volume V of the sample to be tested; specifically including:

[0091] S51: Take 200mL~300mL of Class A reagent and inject it into the No. 1 solution tank of the detection equipment, take an equal volume of Class B reagent and inject it into the No. 2 solution tank of the detection equipment; take 500mL~1000mL of the sample to be tested and add it into the No. 3 solution tank;

[0092] S52: Turn on the power supply, and the single chip computer immediately records the initial output conductivity S0 of the conductivity meter; turn on the peristaltic pump, and add the sample to be tested in the No. 3 solution pool to the No. 1 and No. 2 solution pools. After each 5ml~10ml is added, the conductivity S output by the conductivity meter is recorded. x ;Conductivity S0 and S x Normalize it:

[0093] S=S x - S0

[0094] The SV relationship curve between the conductivity S output by the conductivity meter and the volume V of the sample to be tested is drawn using a single-chip microcomputer, with the starting point being point 0.

[0095] S6: Obtain characteristic points V1 and V2 from the SV relationship curve of the sample to be tested, substitute V1 and V2 into the nonlinear surface formula fitted by the double threshold database of polyaluminum chloride standard aqueous solution, and obtain the concentration Φ and active ingredient content Al of the polyaluminum chloride in the sample to be tested by solving the nonlinear equation group;

[0096] In this step, the characteristic point V1 is the volume V1 of the sample to be detected, corresponding to the maximum value of the conductivity S; the characteristic point V2 is the volume V2 of the sample to be detected, corresponding to the intersection of the curve and the x-axis.

[0097] S7: Based on the mass ratio of machine-made sand to deionized water, the concentration of polyaluminium chloride attached to the machine-made sand is calculated as follows:

[0098] Φ0=Φ×m2 / m1

[0099] Wherein, m1 is the mass of machine-made sand in step S1, and m2 is the mass of deionized water in step S1.

[0100] Thus, the present disclosure provides a method for detecting the concentration and effective component content of residual polyaluminium chloride in machine-made sand, which obtains the concentration Φ0 of polyaluminium chloride attached to the machine-made sand and the effective component content Al of polyaluminium chloride.

[0101] Furthermore, based on the concentration Φ0 of polyaluminium chloride attached to the machine-made sand obtained in the present disclosure and the effective component content Al of polyaluminium chloride, it is possible to further judge whether the machine-made sand raw material from which the machine-made sand sample is obtained can be used for concrete preparation, specifically including:

[0102] When the test result shows that the effective component content of polyaluminium chloride is 26%, when the concentration of polyaluminium chloride Φ0≤0.01%, its effect on the slump and slump loss of concrete is small, and it can be used to prepare concrete; when the concentration of polyaluminium chloride is 0.01%<Φ0≤0.03%, its effect on the slump and slump loss of concrete is significant, and the concrete mix ratio needs to be adjusted, and the amount of water reducer needs to be appropriately increased to meet the slump requirements; when the concentration of polyaluminium chloride Φ0>0.03%, its effect on the slump and slump loss of concrete can no longer be compensated by water reducer, and the machine-made sand needs to be washed twice with clean water before retesting;

[0103] When the test result shows that the effective ingredient content of polyaluminium chloride is 30%, when the concentration of polyaluminium chloride Φ0≤0.005%, its effect on the slump and slump loss of concrete is small, and it can be used to prepare concrete; when the concentration of polyaluminium chloride is 0.005%<Φ0≤0.015%, its effect on the slump and slump loss of concrete is significant, and the concrete mix ratio needs to be adjusted, and the amount of water reducer needs to be appropriately increased to meet the slump requirements; when the concentration of polyaluminium chloride Φ0>0.015%, its effect on the slump and slump loss of concrete can no longer be compensated by water reducer, and the machine-made sand needs to be cleaned twice with clean water before retesting.

[0104] The following examples further illustrate the method for detecting the active ingredient content of a flocculant in manufactured sand, provided by this disclosure. The flocculant is polyaluminum chloride. This example uses manufactured sand coated with polyaluminum chloride as the research object. Following the specific implementation plan, a dual-threshold database of polyaluminum chloride standard aqueous solutions with varying concentrations and active ingredient contents is generated. These solutions are then thoroughly mixed at a 1:1 mass ratio to obtain an aqueous polyaluminum chloride solution containing an unknown active ingredient content, serving as the test sample. Further testing yields conductivity and the corresponding volume of solution added, as shown in Table 1.

[0105]

[0106] Table 1 Conductivity obtained from the test and the volume of the solution sample to be tested

[0107] The SV curve drawn according to Table 1 is as follows Figure 3 、 Figure 4 、 Figure 5 shown.

[0108] Figure 3 The middle dual threshold values were V1=25.47, V2=57.59; Figure 4 The middle dual threshold values were V1=24.56, V2=53.95; Figure 5 The dual threshold values are V1=25.11 and V2=59.30.

[0109] Substituting the above threshold values into the nonlinear surface formula fitted by the database of double threshold values of polyaluminium chloride standard aqueous solution shown in FIG2 , it can be learned that sample 1 contains polyaluminium chloride with a concentration of 0.004% and an active ingredient content of 26%, sample 2 contains polyaluminium chloride with a concentration of 0.012% and an active ingredient content of 26%, and sample 3 contains polyaluminium chloride with a concentration of 0.004% and an active ingredient content of 30%.

[0110] At the same time, since the mass ratio of machine-made sand to water was 1:1 when preparing the samples to be tested, the following residues remained in the three machine-made sand samples:

[0111] Sample 1: Polyaluminium chloride with a concentration of 0.004% and an active ingredient content of 26% has little effect on the slump and slump loss of concrete and can be used to prepare concrete;

[0112] Sample 2: Polyaluminium chloride with a concentration of 0.012% and an active ingredient content of 26% has a significant impact on the slump and slump loss of concrete. The concrete mix ratio needs to be adjusted and the amount of water reducer appropriately increased to meet the slump requirements.

[0113] Sample 3: Polyaluminium chloride with a concentration of 0.004% and an active ingredient content of 30% has little effect on the slump and slump loss of concrete and can be used to prepare concrete.

[0114] The embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It should be noted that any implementations not depicted or described in the drawings or the main text of the specification are known to those skilled in the art and are not described in detail. Furthermore, the above definitions of the various elements and methods are not limited to the various specific structures, shapes, or methods described in the embodiments, and can be easily modified or replaced by those skilled in the art.

[0115] Those skilled in the art will appreciate that the features described in the various embodiments of the present disclosure may be combined and / or coupled in various ways, even if such combinations or couplings are not explicitly described in the present disclosure. In particular, the features described in the various embodiments of the present disclosure may be combined and / or coupled in various ways without departing from the spirit and teachings of the present disclosure. All such combinations and / or couplings fall within the scope of the present disclosure.

[0116] The above describes the embodiments of the present disclosure. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. Without departing from the scope of the present disclosure, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand, characterized in that: The method includes: S1: Prepare samples to be tested, standard samples and detection reagents; S2: Connect detection components and configure detection equipment; S3: Testing the standard sample to obtain the SV relationship curve between the conductivity S output by the conductivity meter of the standard sample and the volume V of the added polyaluminium chloride standard aqueous solution; S4: establishing a double-threshold database of polyaluminium chloride standard aqueous solutions under conditions of different concentrations and different active ingredient contents based on the SV relationship curve of the standard sample, and fitting the double-threshold database of the polyaluminium chloride standard aqueous solution into a nonlinear surface formula; S5: Testing the sample to be tested, and obtaining an SV relationship curve between the conductivity S output by the conductivity meter of the sample to be tested and the volume V of the sample to be tested; S6: Obtain characteristic points V1 and V2 from the SV relationship curve of the sample to be tested, substitute V1 and V2 into a nonlinear surface formula fitted by a database of double threshold values of polyaluminum chloride standard aqueous solutions, and obtain the concentration Φ and active ingredient content Al of the polyaluminum chloride in the sample to be tested by solving the nonlinear equation system; wherein the characteristic point V1 is the volume V1 of the sample to be tested, corresponding to the maximum value of the conductivity S; the characteristic point V2 is the volume V2 of the sample to be tested, corresponding to the intersection of the curve and the x-axis; S7: Calculate the concentration of polyaluminium chloride attached to the machine-made sand according to the mass ratio of the machine-made sand to the deionized water. Wherein, step S4 includes: S41: For each polyaluminium chloride standard aqueous solution with different concentrations of active ingredient content, obtain the range of characteristic points on the curve under conditions of different concentrations and different active ingredient contents, record them as dual thresholds represented by the volume V of the added polyaluminium chloride standard aqueous solution, and establish a database of dual thresholds of polyaluminium chloride standard aqueous solutions under conditions of different concentrations and different active ingredient contents; in the dual thresholds represented by the volume V of the added polyaluminium chloride standard aqueous solution, threshold 1 corresponds to the maximum value of the conductivity S on the curve, which is the corresponding volume V1 of the polyaluminium chloride standard aqueous solution, and threshold 2 corresponds to the volume V2 of the polyaluminium chloride standard aqueous solution corresponding to the intersection of the curve and the x-axis; S42: fitting the database of the double threshold value of the polyaluminium chloride standard aqueous solution into a nonlinear surface formula; the nonlinear surface formula for fitting the database of the double threshold value of the polyaluminium chloride standard aqueous solution is specifically as follows: Among them, the horizontal axis x and the vertical axis y correspond to the concentration Φ and the effective ingredient content Al of the polyaluminum chloride standard sample respectively. Except for V1, V2, Φ and Al, other parameters are constant coefficients.

2. The method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand according to claim 1, wherein: Step S1 includes: S11: Fully mix the machine-made sand sample to be tested and deionized water in a mass ratio of 1:1 to 1:3 to prepare the sample to be tested; S12: Prepare polyaluminium chloride solid samples with different active ingredient contents, ranging from 26% to 30% in steps of 2%; prepare polyaluminium chloride standard aqueous solutions with concentrations of 0.004% to 0.016% using deionized water as standard samples; S13: Prepare Class A and Class B reagents as detection reagents, wherein the Class A reagent can react with polyaluminum chloride and has a relatively obvious reaction phenomenon, and the Class B reagent does not react with polyaluminum chloride but has good conductivity.

3. The method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand according to claim 2, characterized in that: The Class A reagent in step S13 includes: copper sulfate, copper chloride, ferric chloride, potassium chloride, ferrous chloride, nickel chloride, potassium chromate, potassium dichromate or potassium permanganate; the concentration of the Class A reagent is 0.002 mol / L to 0.005 mol / L; The type B reagent in step S13 includes: sodium sulfate, potassium sulfate, magnesium sulfate, ferrous sulfate or ferrous sulfate; the concentration of the type B reagent is 0.001 mol / L~0.003 mol / L.

4. The method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand according to claim 3, characterized in that: Step S2 includes: S21: Connect the solution pools numbered 1 and 2 in series with copper wires, connect the positive electrode of solution pool No. 1 to the negative electrode of solution pool No. 2, and then connect them to the positive and negative electrodes of the conductivity meter; use hoses to connect solution pools No. 1 and 2 to solution pool No. 3, set up a peristaltic pump in the middle, and adjust the peristaltic pump flow rate to 2-5 ml / min; among them, solution pools No. 1 and No. 2 are used as test solution pools, respectively for holding Class A and Class B reagents used in the test process; solution pool No. 3 is the solution pool for testing, used for holding standard samples or samples to be tested used in the test process; S22: Prepare a 4-channel synchronous electromagnetic stirrer with a rotation speed of 100 rpm to 500 rpm.

5. The method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand according to claim 4, characterized in that: Step S3 includes: S31: Take 200mL~300mL of Class A reagent and inject it into the No. 1 solution tank of the detection equipment, and take another portion of the same volume of Class B reagent and inject it into the No. 2 solution tank of the detection equipment; take 500mL~1000mL of standard sample and add it into the No. 3 solution tank; S32: Turn on the power supply, and the single chip microcomputer immediately records the initial conductivity output conductivity S0; turn on the peristaltic pump, and add the polyaluminium chloride standard aqueous solution in the No. 3 solution tank to the No. 1 and No. 2 solution tanks. After each addition of 5ml~10ml, record the conductivity meter output conductivity S x ;Conductivity S0 and S x Normalize it: S=S x -S0 The SV relationship curve between the conductivity S output by the conductivity meter and the volume V of the added polyaluminium chloride standard aqueous solution was drawn using a single chip microcomputer, with the starting point being point 0.

6. The method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand according to claim 4, characterized in that: Step S5 includes: S51: Take 200mL~300mL of Class A reagent and inject it into the No. 1 solution tank of the detection equipment, take an equal volume of Class B reagent and inject it into the No. 2 solution tank of the detection equipment; take 500mL~1000mL of the sample to be tested and add it into the No. 3 solution tank; S52: Turn on the power supply, and the single chip computer immediately records the initial output conductivity S0 of the conductivity meter; turn on the peristaltic pump, and add the sample to be tested in the No. 3 solution pool to the No. 1 and No. 2 solution pools. After each 5ml~10ml is added, the conductivity S output by the conductivity meter is recorded. x ;Conductivity S0 and S x Normalize it: S=S x - S0 The SV relationship curve between the conductivity S output by the conductivity meter and the volume V of the sample to be tested is drawn using a single-chip microcomputer, with the starting point being point 0.

7. The method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand according to claim 1, characterized in that: The calculation method used in step S7 to obtain the concentration Φ0 of polyaluminium chloride attached to the machine-made sand is: Φ0=Φ×m2 / m1 Wherein, m1 is the mass of machine-made sand in step S1, and m2 is the mass of deionized water in step S1.

8. The method for detecting the concentration of residual polyaluminium chloride and the content of effective ingredients in machine-made sand according to claim 1, characterized in that: The method further includes: Based on the calculated concentration Φ0 of polyaluminium chloride attached to the machine-made sand and the effective component content Al of polyaluminium chloride, it is determined whether the machine-made sand raw materials used to obtain the machine-made sand sample can be used for concrete preparation, wherein: When the test result shows that the effective component content of polyaluminium chloride is 26%, when the concentration of polyaluminium chloride Φ0≤0.01%, its effect on the slump and slump loss of concrete is small, and it can be used to prepare concrete; when the concentration of polyaluminium chloride is 0.01%<Φ0≤0.03%, its effect on the slump and slump loss of concrete is significant, and the concrete mix ratio needs to be adjusted, and the amount of water reducer needs to be appropriately increased to meet the slump requirements; when the concentration of polyaluminium chloride Φ0>0.03%, its effect on the slump and slump loss of concrete can no longer be compensated by water reducer, and the machine-made sand needs to be washed twice with clean water before retesting; When the test result shows that the effective ingredient content of polyaluminium chloride is 30%, when the concentration of polyaluminium chloride Φ0≤0.005%, its effect on the slump and slump loss of concrete is small, and it can be used to prepare concrete; when the concentration of polyaluminium chloride is 0.005%<Φ0≤0.015%, its effect on the slump and slump loss of concrete is significant, and the concrete mix ratio needs to be adjusted, and the amount of water reducer needs to be appropriately increased to meet the slump requirements; when the concentration of polyaluminium chloride Φ0>0.015%, its effect on the slump and slump loss of concrete can no longer be compensated by water reducer, and the machine-made sand needs to be cleaned twice with clean water before retesting.

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