A rapid self-detection method of effective calcium content based on conductivity test

Abstract

The application provides a quick self-detection method of effective calcium content based on conductivity test, and relates to the technical field of road engineering detection. The quick self-detection method of effective calcium content comprises the following steps: configuring ammonium chloride solution and lime stabilized material; putting the lime stabilized material into a beaker, adding water, and configuring into a mixed solution; assembling and calibrating a conductivity meter, erecting an electrode and a burette; using the ammonium chloride solution to conduct titration experiment, and detecting the conductivity of the solution by using the conductivity meter; recording the corresponding relationship between the titration amount of the ammonium chloride solution and the conductivity, drawing a curve image, and finding the titration amount of the ammonium chloride solution at the reaction end point; and calculating the effective calcium content in the lime stabilized material according to the titration amount at the reaction end point. The application accurately detects the effective calcium content in the lime stabilized material through the change rule of the conductivity, simplifies the experimental steps, does not need to draw a standard curve, shortens the detection time, and improves the detection and construction efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of road engineering detection, and particularly relates to a rapid self-detection method of effective calcium content based on conductivity test. BACKGROUND

[0002] Lime stabilized material is widely used in roads, which can effectively improve the bearing capacity, stability and durability of roads. However, in the actual application, the effective calcium content in the lime stabilized material is the key to construction. Too low or too high effective calcium content will lead to substandard road strength, stability and compaction. Therefore, how to quickly and accurately detect the effective calcium content in the lime stabilized material is an important link in the field of construction quality control.

[0003] The commonly used methods for detecting the effective calcium content in the lime stabilized material include EDTA titration method and direct-reading calcium meter method. However, the existing methods have the following problems: (1) The existing methods need to draw a standard curve through multiple experiments before starting the detection work, and determine the effective calcium content in the lime stabilized material according to the standard curve and the detection result of the sample to be tested. In the whole detection process, there are also steps such as repeatedly extracting and transferring the upper clear liquid, which is complex and time-consuming. (2) The existing methods need to use multiple chemical reagents in the detection process, and the strong alkali solution such as sodium hydroxide is included, which has a huge safety risk. (3) The detection result of the traditional EDTA titration method is judged by the color change of the human eye, which has a large human error. (4) The electrode used in the traditional direct-reading calcium meter is inevitably worn out in the detection process due to the increase of the number of uses and the influence of chemical components in the detection solution, which affects the accuracy of the detection result and needs to be repaired or replaced regularly. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a rapid self-detection method of effective calcium content based on conductivity test. By using the examples of the present application, the problems of the traditional effective calcium content detection method, such as the need to draw a standard curve, the complex detection steps, the use of dangerous chemical reagents in the detection process, and the influence of equipment and manual processing on the detection result, can be solved. The effective calcium content is determined by directly detecting the conductivity variation of the lime stabilized material mixed solution, which simplifies the experimental steps, improves the detection efficiency and the accuracy of the detection result.

[0005] To achieve the above object, the present application is implemented by the following technical solutions:

[0006] A rapid self-detection method of effective calcium content based on conductivity test, the detection method comprising the following steps:

[0007] S1, configure the ammonium chloride solution with mass fraction a, and configure the lime stabilized material with mass M by using slaked lime, soil and water to achieve the optimal water content;

[0008] S2, put the lime stabilized material into a beaker, add a certain amount of water to configure a mixed solution;

[0009] S3, assemble and calibrate the conductivity meter, and set up electrodes and a burette above the mixed solution, and inject a sufficient amount of ammonium chloride solution into the burette as a titration solution;

[0010] S4, continuously add the ammonium chloride solution to the mixed solution, and detect the solution conductivity by using the conductivity meter during the titration process;

[0011] S5, record the corresponding relationship between the titration amount of the ammonium chloride solution and the solution conductivity, draw a conductivity-titration amount curve image, mark the curve inflection point as the reaction endpoint, and record the titration amount of the ammonium chloride solution at the reaction endpoint;

[0012] S6, calculate the effective calcium content in the lime stabilized material according to the titration amount of the ammonium chloride solution at the reaction endpoint;

[0013] Preferably, the calculation method of the effective calcium content is as follows:

[0014]

[0015] In the formula, x 检测 is the effective calcium content in the lime stabilized material detected; m 检测钙 is the mass of the effective calcium detected; m 土 is the mass of the soil in the lime stabilized material; Mr 氯化铵 is the relative molecular mass of ammonium chloride; Mr 氢氧化钙 is the relative molecular mass of calcium hydroxide; h is the titration amount of the ammonium chloride solution at the reaction endpoint; and a is the mass fraction of the ammonium chloride solution.

[0016] Preferably, the configuration method of the lime stabilized material in step S1 comprises the following steps:

[0017] S1-1, take the soil and slaked lime used on the construction site, and dry the soil and slaked lime;

[0018] S1-2, take water and the dried soil and slaked lime, and configure the lime stabilized material with mass M to achieve the optimal water content, and the formula for taking water, soil and slaked lime is as follows:

[0019] M = m 土 + m 配置钙 + m 水

[0020]

[0021] M is the total mass of lime-stabilized material; m 土 m is the mass of soil in lime-stabilized material; m 配置钙 m is the mass of slaked lime in lime-stabilized material; m 水 m is the mass of water in lime-stabilized material; ω is the optimum water content of lime-stabilized material; x 配置 m is the effective calcium content of lime-stabilized material.

[0022] Preferably, the titration tube in step S3 is injected with sufficient ammonium chloride solution, and the judgment formula is:

[0023]

[0024] L is the minimum volume of the required ammonium chloride solution; m 钙max m is the maximum effective calcium mass in lime-stabilized material; ρ is the density of ammonium chloride solution; a is the mass fraction of ammonium chloride solution; Mr 氯化铵 Mr is the relative molecular mass of ammonium chloride; Mr 氢氧化钙 Mr is the relative molecular mass of calcium hydroxide; t is the volume of ammonium chloride solution for each titration.

[0025] Preferably, the specific operation method in step S4 includes the following steps:

[0026] S4-1, control the titration of the burette to the beaker with ammonium chloride solution, 2mL of ammonium chloride solution for each titration;

[0027] S4-2, use a stirring rod to stir and stand for 30s, so that the ammonium chloride reacts with the calcium hydroxide in the mixed solution to generate calcium chloride, change the number and type of ions in the solution, and the conductivity changes, and the conductivity of the solution at this time is detected using a conductivity meter;

[0028] S4-3, repeat steps S4-1 and S4-2, after each titration, stir the solution to make the ammonium chloride fully react with the calcium hydroxide in the mixed solution, when the calcium hydroxide is completely reacted, titrate the ammonium chloride solution, no chemical reaction occurs, only the number of ions in the solution changes, the conductivity changes, and the conductivity change rate before and after the complete reaction of calcium hydroxide is different, the solution conductivity is detected during the period, and the titration continues until the ammonium chloride solution is consumed.

[0029] Preferably, the specific operation method of step S5 includes the following steps:

[0030] S5-1: according to step S4, record the corresponding relationship between the titration amount of ammonium chloride solution and the conductivity of the mixed solution, and draw a conductivity-titration amount curve image according to the corresponding relationship;

[0031] S5-2: According to the conductivity-titration amount image, find the inflection point of the curve, mark it as the reaction end point, and determine the titration amount of the ammonium chloride solution corresponding to the reaction end point.

[0032] The application provides a rapid self-detection method for effective calcium content based on conductivity testing.

[0033] (1) The application provides a rapid self-detection method for effective calcium content based on conductivity testing, which only needs to perform a conductivity test in a container containing a lime stabilizing material mixed solution, so that the effective calcium content in the lime stabilizing material can be accurately measured, the problems of complex traditional detection steps and the need to perform multiple experiments to draw a standard curve during detection are overcome, the experimental operation steps are simplified, the detection time is shortened, and the detection and construction efficiency are effectively improved.

[0034] (2) The application provides a rapid self-detection method for effective calcium content based on conductivity testing, which does not need to accurately measure the conductivity of the lime stabilizing material mixed solution, but only needs to determine the conductivity change rule to quantify the effective calcium content in the lime stabilizing material, avoids the inaccuracy of conductivity measurement caused by electrode wear and the resulting inaccuracy of effective calcium content detection results, overcomes the problems of eye recognition error or influence of electrode wear state existing in traditional detection methods, and improves the reliability of detection results.

[0035] (3) The application provides a rapid self-detection method for effective calcium content based on conductivity testing, which only uses ammonium chloride solution as a chemical reagent to complete the effective calcium content detection work, overcomes the problem of great safety risk caused by the use of multiple chemical reagents including sodium hydroxide strong alkali solution in traditional detection methods, reduces the safety risk of detection work, and reduces the harm to operators in the detection process. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The application provides a rapid self-detection method for effective calcium content based on conductivity testing.

[0037] Figure 2 The application provides a rapid self-detection method for effective calcium content based on conductivity testing.

[0038] Figure 3 The application provides a rapid self-detection method for effective calcium content based on conductivity testing. DETAILED DESCRIPTION

[0039] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work belong to the scope of protection of the present application.

[0040] Embodiment 1

[0041] A rapid self-detection method of effective calcium content based on conductivity test, such as Figure 1 , comprising the following steps:

[0042] S1: configure an ammonium chloride solution with a mass fraction of 10%, and use lime, soil and water to configure lime stabilized materials with a mass of 100g and an optimal water content;

[0043] S1-1: take 200g of anhydrous ammonium chloride solid and 1800g of water to configure 2000g of an ammonium chloride solution with a mass fraction of 10%;

[0044] S1-2: take soil and lime for construction site, and dry the soil and lime;

[0045] S1-3: take a certain amount of water and the dried soil and lime, and configure lime stabilized materials with a mass of 100g and an effective calcium content of 3% and an optimal water content.

[0046] The method for quantitatively taking lime, soil and water is as follows:

[0047] M = m 土 +m 配置钙 +m 水 = 100

[0048]

[0049] m 水 = ω * (m 土 +m 配置钙 ) = 0.1405 * (85.13 + 2.55) ≈ 12.32

[0050] In the formula, M is the total mass of the lime stabilized materials; m 土 is the mass of the soil in the lime stabilized materials; m 配置钙 is the mass of the lime in the configured lime stabilized materials; m 水 is the mass of the water in the lime stabilized materials; ω is the optimal water content of the lime stabilized materials; and x 配置 is the effective calcium content of the lime stabilized materials.

[0051] The quality of slaked lime, soil and water used is shown in Table 1.

[0052] Table 1

[0053]

[0054] S2: Put the lime stabilizing material into a beaker, add 400 mL of water, and configure it as a mixed solution;

[0055] S2-1: Take 100 g of lime stabilizing material with an effective calcium content of 3% and put it into a beaker, and add 400 mL of water to the beaker to form a mixed solution, use a stirring rod to stir the mixed solution, and stand for 10 minutes.

[0056] S3: Assemble and calibrate the conductivity meter, and set up the electrode and burette above the above-mentioned mixed solution, and inject a sufficient amount of ammonium chloride solution into the burette as a titration solution;

[0057] S3-1: Select an electrode with an electrode constant of 10, connect the electrode to the conductivity meter, and calibrate the conductivity meter using a conductivity standard solution;

[0058] S3-2: Insert the electrode into the mixed solution to detect the conductivity of the mixed solution, and set up the burette above the beaker, and inject a sufficient amount of 10% ammonium chloride solution into the burette.

[0059] The injection of a sufficient amount of ammonium chloride solution takes into account the complete reaction of calcium hydroxide in slaked lime. In this embodiment, lime stabilizing material with an effective calcium content of 3% is configured, and in different construction sites, the minimum amount of ammonium chloride solution required should be calculated according to the highest effective calcium content, and after ensuring that the calcium hydroxide in the lime stabilizing material with the highest effective calcium content is completely reacted, at least 10 titrations are still performed, and a complete conductivity-titration curve image is drawn. The calculation formula of the minimum amount of ammonium chloride solution required in this embodiment is as follows:

[0060]

[0061] Since 100 mL > 55.28 mL, more than 10 titrations can be performed after the calcium hydroxide is completely reacted, so 100 mL of ammonium chloride solution is injected into the burette.

[0062] S4: Continuously add ammonium chloride solution to the above-mentioned mixed solution, and detect the conductivity of the solution during titration using the conductivity meter;

[0063] S4-1: Control the burette to titrate the ammonium chloride solution into the beaker, and each time titrate 2 mL of ammonium chloride solution;

[0064] S4-2: Stirring with a stirring rod and standing for 30s, ammonium chloride reacts with calcium hydroxide in the mixed solution to generate calcium chloride, changing the number and type of ions in the solution, and the conductivity rises. The conductivity of the solution at this time is detected using a conductivity meter;

[0065] S4-3: Repeat steps S4-1 and S4-2. After each titration is completed, stir the solution to allow ammonium chloride to fully react with calcium hydroxide in the mixed solution. When the calcium hydroxide is completely reacted, titrate the ammonium chloride solution, which does not undergo a chemical reaction. The number of ions in the solution increases, and the conductivity rises. The conductivity rises at different rates before and after the complete reaction of calcium hydroxide. The conductivity of the solution is detected during this period until the ammonium chloride solution is consumed.

[0066] S5: Record the corresponding relationship between the titration amount of ammonium chloride solution and the conductivity of the solution. According to the corresponding relationship, draw the conductivity-titration amount curve image. The inflection point of the curve is recorded as the reaction endpoint, and the titration amount of ammonium chloride solution at the reaction endpoint is recorded.

[0067] S5-1: According to step S4, as the titration amount of ammonium chloride solution increases, the conductivity of the mixed solution continues to rise. The corresponding relationship between the titration amount of ammonium chloride solution and the conductivity of the mixed solution is recorded, as shown in Table 2.

[0068] Table 2

[0069]

[0070]

[0071] According to the above corresponding relationship, draw the conductivity-titration amount curve image, as shown in Figure 2 .

[0072] S5-2: According to the curve image of Figure 2 , the inflection point of the curve is the point where the titration amount is 38ml. This point is recorded as the reaction endpoint, i.e. the calcium hydroxide in the mixed solution is completely reacted. After that, titrating the ammonium chloride solution does not undergo a chemical reaction, and the conductivity of the mixed solution increases at different rates before and after the complete reaction of calcium hydroxide. Therefore, the conductivity-titration amount curve image has an inflection point. The titration amount of ammonium chloride solution at the reaction endpoint is determined and recorded according to the inflection point.

[0073] S6: According to the titration amount of ammonium chloride solution at the reaction endpoint h = 38ml, calculate the effective calcium content in the lime stabilization material.

[0074] The calculation method of the effective calcium content is as follows:

[0075]

[0076] The effective calcium content x of the lime stabilization material is 3.09%, and the detection is accurate.

[0077] Example 2

[0078] S1: Step S1 is the same as in Example 1, the configuration mass is 100 g, the effective calcium content is 6%, and the lime stabilized material reaches the optimum water content;

[0079] The masses of the slaked lime, the soil, and the water used are shown in Table 3.

[0080] Table 3

[0081]

[0082] S2: Step S2 is the same as in Example 1.

[0083] S3: Step S3 is the same as in Example 1, and the injection of the sufficient amount of the ammonium chloride solution is calculated according to the following formula:

[0084]

[0085] Since 100 mL > 87.25 mL, more than 10 titrations can be performed after the calcium hydroxide reaction is complete, and therefore 100 mL of the ammonium chloride solution is injected into the burette.

[0086] S4: Step S4 is the same as in Example 1.

[0087] S5: Step S5 is the same as in Example 1, and the corresponding relationship between the titration amount of the ammonium chloride solution and the conductivity of the mixed solution is shown in Table 4.

[0088] Table 4

[0089]

[0090]

[0091] According to the above-mentioned corresponding relationship, a conductivity-titration amount curve image is drawn, as shown in Figure 3 According to the curve image, the inflection point of the curve is the point at which the titration amount is 70 ml, and this point is recorded as the reaction endpoint. Figure 3

[0092] S6: According to the reaction endpoint ammonium chloride solution titration amount h = 70 ml, the effective calcium content in the lime stabilized material is calculated.

[0093] The calculation method of the effective calcium content is as follows:

[0094]

[0095] The effective calcium content of the lime stabilized material is x = 5.98%, and the detection is accurate.

[0096] ​The above embodiment 1 and embodiment 2 are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features therein can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A rapid self-detection method of available calcium content based on conductivity test, characterized in that, The detection method comprises the following steps: S1, configure the ammonium chloride solution with a mass fraction of a, and use slaked lime, soil and water to configure the lime stabilized material with a mass of M and reaching the optimal water content; S2, put the lime stabilized material into a beaker, add a certain amount of water to configure a mixed solution; S3, assemble and calibrate the conductivity meter, and set the electrode and burette above the mixed solution, and inject a sufficient amount of ammonium chloride solution into the burette as a titration solution; S4, continuously add the ammonium chloride solution into the mixed solution, and detect the solution conductivity during the titration process by using the conductivity meter; S5, record the corresponding relationship between the titration amount of the ammonium chloride solution and the solution conductivity, draw the conductivity-titration amount curve image, mark the inflection point of the curve as the reaction endpoint, and record the titration amount of the ammonium chloride solution at the reaction endpoint; S6, calculate the effective calcium content in the lime stabilized material according to the titration amount of the ammonium chloride solution at the reaction endpoint; The calculation method of the effective calcium content is: wherein x 检测 is the effective calcium content in the lime-stabilized material detected; m 检测钙 is the mass of the effective calcium detected; m 土 is the mass of the soil in the lime-stabilized material; Mr 氯化铵 is the relative molecular mass of ammonium chloride; Mr 氢氧化钙 is the relative molecular mass of calcium hydroxide; h is the titration amount of the ammonium chloride solution at the end of the reaction; and a is the mass fraction of the ammonium chloride solution.

2. The method for rapid self-detection of available calcium content based on conductivity test according to claim 1, characterized in that: The configuration method of the lime stabilized material in step S1 comprises the following steps: S1-1, take the soil and slaked lime on the construction site, and dry the soil and slaked lime; S1-2, take water, and dry soil and slaked lime, and configure the lime stabilized material with a mass of M and reaching the optimal water content, the formula for taking water, soil and slaked lime is: M = m 土 + m 配置钙 + m 水 m 水 = ω * (m 土 + m 配置钙 ) where M is the total mass of the lime stabilized material; m 土 is the mass of the soil in the lime stabilized material; m 配置钙 is the mass of the slaked lime in the lime stabilized material; m 水 is the mass of the water in the lime stabilized material; ω is the optimum water content of the lime stabilized material; x 配置 is the effective calcium content of the lime stabilized material.

3. The method of claim 1, wherein the method is characterized by: The judgment formula for injecting a sufficient amount of ammonium chloride solution into the burette in step S3 is: where L is the minimum volume of the desired ammonium chloride solution; m 钙max is the maximum effective calcium mass in the lime stabilisation material; p is the density of the ammonium chloride solution; a is the mass fraction of the ammonium chloride solution; Mr 氯化铵 is the relative molecular mass of the ammonium chloride; Mr 氢氧化钙 is the relative molecular mass of the calcium hydroxide; t is the volume of the ammonium chloride solution for each titration.

4. The method of claim 1, wherein the method is characterized by: The specific operation method in step S4 comprises the following steps: S4-1, control the burette to titrate 2 mL of ammonium chloride solution into the beaker each time; S4-2, use a stirring rod to stir and stand for 30 s, so that the ammonium chloride fully reacts with the calcium hydroxide in the mixed solution to generate calcium chloride, changes the ion quantity and type in the solution, and changes the conductivity, and the conductivity meter is used to detect the conductivity of the solution at this time; S4-3, repeat steps S4-1 and S4-2, after each titration, stir the solution, so that the ammonium chloride fully reacts with the calcium hydroxide in the mixed solution, when the calcium hydroxide is completely reacted, titrate the ammonium chloride solution, no chemical reaction occurs, only the ion quantity in the solution changes, the conductivity changes, the conductivity change rates before and after the complete reaction of the calcium hydroxide are different, and the solution conductivity is detected during the period, and the titration continues until the ammonium chloride solution is consumed.

5. The method for rapid self-detection of available calcium content based on conductivity test according to claim 1, characterized in that: The specific operation method of step S5 comprises the following steps: S5-1: according to step S4, record the corresponding relationship between the titration amount of the ammonium chloride solution and the conductivity of the mixed solution, and draw the conductivity-titration amount curve image according to the corresponding relationship; S5-2: find the inflection point of the curve according to the conductivity-titration amount curve image, mark the inflection point as the reaction endpoint, and determine the titration amount of the ammonium chloride solution corresponding to the reaction endpoint.

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