Active detection method for lime dosage in lime stabilized soil for traffic infrastructure

Abstract

The invention provides a method for actively detecting the dosage of lime in lime stabilized soil for traffic infrastructure, and relates to the technical field of lime detection. The rapid detection method mainly comprises the following steps: preparing a plurality of test reagents, respectively adding a plurality of groups of lime stabilized soil containing different lime doses into an ammonium chloride solution to form a mixed solution, titrating the mixed solution by using a titrating solution, and detecting the conductivity of the solution, drawing a relation image of the solution conductivity and the dosage of the titrating solution, determining the dosage of the titrating solution when the conductivity is lowest, establishing a function relation between the lime dosage and the dosage of the titrating solution when the conductivity is lowest, repeating the steps and calculating the dosage of the lime in the to-be-detected lime stabilized soil in combination with the function relation. The invention overcomes the defects in the prior art, provides a new method for detecting the lime dosage of the lime-stabilized soil, and can quickly and accurately measure the lime dosage through the change of the conductivity in the solution and the characterization of the reaction process, thereby further improving the working efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of lime detection, and in particular to a method for actively detecting lime dosage in lime-stabilized soil for transportation infrastructure. Background Art

[0002] In the construction of transportation infrastructure, lime-stabilized soil plays an indispensable role as an important building material. It is widely used in roadbeds, pavement bases, tunnel foundations and bridge foundations, and can effectively improve the strength, stability and durability of transportation infrastructure. Lime dosage is very important in the application of lime-stabilized soil. If the lime dosage is too low, the reinforcement effect of lime on the stabilized soil is limited, resulting in insufficient strength of the lime-stabilized soil; too low lime dosage will also reduce the water stability of lime-stabilized soil. In a humid or underwater environment, this soil is prone to softening or scouring, thus affecting the normal use of the road. However, if the lime dosage is too high, too much lime will exist in the soil in the form of free ash, which will lead to a decrease in the strength of the lime-stabilized soil. This is because too much lime cannot fully react with the minerals in the soil to form invalid lime clumps. Therefore, the ability to accurately and quickly determine the lime dosage in lime-stabilized soil in the construction of transportation infrastructure has always been the object of research.

[0003] The existing traditional methods for lime detection include EDTA titration and direct-reading calcium meter method. The EDTA titration method has the following disadvantages: the operation is complicated, the results are presented based on the judgment of color changes, which is subjective, and because the lime-stabilized soil is treated with a variety of chemical reagents, the various chemical reagents and the chemical reagents and calcium ions interact with each other during the detection process, affecting the accuracy of the test results. The direct-reading calcium meter method detects the concentration of calcium ions, which will be affected by the temperature and pressure of the construction site, and the test results are not accurate enough; before use, one end of the calcium electrode needs to be immersed in a standard solution of calcium chloride for a long time to activate the electrode. Therefore, a method that can quickly, efficiently and accurately measure the lime dosage is needed. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for actively detecting lime dosage in lime-stabilized soil for transportation infrastructure, which can effectively detect lime dosage and improve the accuracy and universality of detection.

[0005] The specific technical solutions are as follows:

[0006] An active detection technology for lime dosage in lime-stabilized soil for transportation infrastructure, the rapid detection method comprising the following steps:

[0007] S1. Prepare a 15% sodium sulfate solution as a titration solution, and prepare a 5% ammonium chloride solution for standby use, and prepare n groups of lime-stabilized soils with different lime dosages, where n≥5;

[0008] S2, respectively adding n groups of lime-stabilized soil into an excess of ammonium chloride solution and stirring evenly to obtain n groups of mixed solutions;

[0009] S3, using a titrator to titrate the titrant into the n groups of mixed solutions and stir evenly;

[0010] S4, using a conductivity meter to test the conductivity of the n groups of mixed solutions after the titration, and recording the conductivity of each group of mixed solutions after each titration;

[0011] S5, using the dosage of the consumed titrant as the abscissa and the conductivity of the mixed solution as the ordinate to draw a graph showing the relationship between the conductivity of the mixed solution and the dosage of the consumed titrant, and determining the dosage of the titrant when the conductivity is the lowest;

[0012] S6. Establish a functional relationship between the lime dosage and the titration solution dosage when the conductivity is the lowest;

[0013] S7. Use S2-S5 to determine the dosage of the titrant required when the conductivity of the lime-stabilized soil to be tested is the lowest, and calculate the lime dosage in combination with the functional relationship in S6.

[0014] Preferably, the preparation method of the lime-stabilized soil is to mix lime with the soil to be stabilized to prepare a dry mixture, and then add water to the dry mixture for wet mixing, so that the mixture reaches an optimal water content to form a wet mixture, that is, lime-stabilized soil. The proportion calculation of each component in the wet mixture includes the following steps:

[0015] S1-1. According to the optimum moisture content of lime-stabilized soil and the mass of wet mixture, the mass calculation formula of dry mixture is as follows:

[0016]

[0017] In the formula: m1 is the mass of dry mixture, m2 is the mass of wet mixture, w1 is the optimum moisture content;

[0018] S1-2. Determine the dry mass of the stabilized soil according to the mass of the dry mixture and the lime dosage. The calculation formulas for the dry mass of the stabilized soil and the mass of dry lime are as follows:

[0019]

[0020] Where: m3—dry mass of stabilized soil, m1—dry mixture mass, X i %—lime dosage;

[0021] m4=m1-m3

[0022] In the formula: m4 is the mass of dry lime, m3 is the dry mass of stabilized soil, m1 is the mass of dry mixture;

[0023] S1-3. According to the dry mass of the stabilized soil and the air-dried moisture content of the stabilized soil, the wet mass of the stabilized soil is calculated as follows:

[0024] m5=m3*(1+w2)

[0025] Where: m5 is the wet mass of the stabilized soil, m3 is the dry mass of the stabilized soil, w2 is the air-dried moisture content of the stabilized soil;

[0026] S1-4, according to the dry lime mass and the air-dried moisture content of the lime, determine the wet lime mass, the wet lime mass calculation formula is as follows:

[0027] m6=m4*(1+w3)

[0028] m6—wet lime mass, m4—dry lime mass, w3—air-dried lime moisture content;

[0029] S1-5. The formula for calculating the mass of water to be added to lime-stabilized soil is as follows:

[0030] m7=m2-m5-m6

[0031] In the formula: m7 is the mass of water to be added, m2 is the mass of wet mixture, m5 is the wet mass of stabilized soil, and m6 is the mass of wet lime.

[0032] Preferably, the wet mix is ​​prepared by adding water to the dry mix while stirring.

[0033] Preferably, the soil to be stabilized is construction soil that does not contain lime.

[0034] Preferably, in step S3, the titrator is set to titrate the solution once every 5 seconds, the titrator is set to titrate a dosage of 2-5 mL each time, and the titration termination condition is set to terminate the titration when the total titration amount is 100-200 mL.

[0035] Preferably, in step S4, the conductivity meter is set as follows: the measurement range is set to 0-200 ms / cm; the electrode constant is set to 10.0; and the temperature compensation knob is set to 20-25°C.

[0036] The present invention provides a method for actively detecting lime dosage in lime-stabilized soil for transportation infrastructure, which has the advantages of:

[0037] (1) Compared with the traditional direct-reading calcium meter method and EDTA titration method which are easily affected by temperature and pressure and have large errors, the present invention is to dissolve lime-stabilized soil in ammonium chloride solution, gradually add titration solution to the solution, so that calcium element forms a precipitate and is separated, and the conductivity of the solution gradually decreases. After the calcium element is completely reacted, titration solution is added again, and the conductivity of the solution gradually increases. The dosage of lime in the lime-stabilized soil is calculated by the dosage of titration solution at the minimum conductivity. The method of the present invention detects the conductivity of the solution by generating calcium element precipitation and determines the dosage of lime. The reaction mode is stable, the minimum conductivity is easy to determine, and the experimental error is reduced. The detection result is only related to the dosage of titration solution at the minimum conductivity, and has nothing to do with the specific value of the solution conductivity. It will not be affected by factors such as temperature and pressure, and the measurement result is more precise and accurate.

[0038] (2) Compared with the traditional direct-reading calcium meter method and EDTA method, the direct-reading calcium meter needs to activate the electrode before measurement, and the electrode is immersed in a calcium chloride standard solution for a period of time before measurement; the EDTA titration method needs to prepare a large number of experimental instruments and experimental reagents, and the operation is cumbersome, while the present invention only needs to take soil as a scale, and the lime-stabilized soil to be tested needs to be tested. Only two reagents, ammonium chloride solution and titration solution, are needed, which overcomes the problem that the traditional detection method needs to use multiple chemical reagents, resulting in the interaction between various chemical reagents and between chemical reagents and calcium ions affecting the accuracy of the inspection results. The operation is simpler and there is no need for complicated, cumbersome and time-consuming pre-test preparations. In addition, in the process of titrating the solvent with the titration solution, the dosage of the titration solution can be increased each time after the solution shows an obvious upward trend, so the inspection speed is faster and the efficiency is higher.

[0039] (3) Compared with the traditional direct-reading calcium meter method and EDTA titration method, the present invention uses different dosages of lime-stabilized soil as a scale, and quantitatively calculates its lime dosage by interpolation. While the measurement results are accurate, the measurement range can be freely adjusted according to the specific working conditions, achieving a balance between the measurement range and the measurement accuracy, and having strong engineering universality. It overcomes the problem that the EDTA titration method has poor measurement accuracy, and the direct-reading calcium meter has high detection accuracy but a small detection range, and the two cannot be achieved at the same time, and cannot be flexibly applied to various engineering situations. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A flow chart of the design method of the present invention;

[0041] Figure 2 This is the relationship between the titration of the experimental soil sodium sulfate solution with a 3% lime dosage and the conductivity;

[0042] Figure 3 This is the relationship between the titration of the experimental soil sodium sulfate solution with a 4% lime dosage and the conductivity;

[0043] Figure 4 This is the relationship between the titration of sodium sulfate solution and the conductivity of the experimental lime-stabilized soil with a lime dosage of 6%;

[0044] Figure 5 This is the relationship between the titration of sodium sulfate solution and the conductivity of the experimental lime-stabilized soil with a lime dosage of 8%;

[0045] Figure 6 This is the relationship between the titration of sodium sulfate solution and the conductivity of the experimental lime-stabilized soil with a lime dosage of 10%;

[0046] Figure 7 It is a graph showing the functional relationship between lime dosage and the titration amount of sodium sulfate solution at the lowest point;

[0047] Figure 8 This is a graph showing the relationship between the titration amount of sodium sulfate solution and the electrical conductivity of the lime-stabilized soil (lime dosage is 7%) to be tested. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Example:

[0050] An active detection method for lime dosage in lime-stabilized soil for transportation infrastructure:

[0051] (1) Prepare experimental reagents: 5% ammonium chloride solution and 15% sodium sulfate solution; take 50g of lime-stabilized soil to be tested from the construction site; prepare 3%, 4%, 6%, 8%, and 10% lime-stabilized soil for experiments, with a mass of 50g. The specific preparation steps are as follows:

[0052] ① According to the environmental conditions of the construction site, it is known that the air-dried moisture content of the stabilized soil is 12.5%, and the air-dried moisture content of the lime is 1.9%. According to the optimal moisture content relationship of lime-stabilized soil in Table 1 below, the mass of each component of lime-stabilized soil with a lime dosage of 3% is calculated:

[0053] Table 1

[0054] Serial number Lime Dosage Optimum moisture content (%) <![CDATA[Maximum dry density (g / cm 3 )]]> 1 3％ 14.11 1.7622 2 4％ 15.02 1.7403 3 6％ 17.51 1.7260 4 8％ 18.60 1.686 5 10％ 19.40 1.678

[0055] Step 1: Calculate dry mix mass

[0056] Use the formula:

[0057] Substitute: dry mix mass = 43.82 g

[0058] Step 2: Calculate the dry mass of the stabilized soil

[0059] Use the formula:

[0060] Substitute: Dry mass of stabilized soil = 42.54 g

[0061] Step 3: Calculate the mass of dry lime

[0062] Formula used: dry lime mass = dry mixture mass - dry mass of stabilized soil

[0063] Substitute: dry lime mass = 43.82-42.54 = 1.28g

[0064] Step 4: Calculate the wet mass of the stabilized soil

[0065] Formula used: Wet mass of stabilized soil = dry mass of stabilized soil * (1 + air-dried moisture content of stabilized soil)

[0066] Substitute: Wet mass of stabilized soil = 42.54*(1+0.125) = 42.54*1.125 = 47.86g

[0067] Step 5: Calculate the wet lime mass

[0068] Formula used: Wet lime mass = dry lime mass * (1 + air-dried lime moisture content)

[0069] Substitute: wet lime mass = 1.28*(1+0.019) = 1.28*1.019 = 1.30 grams

[0070] Step 6: Calculate the mass of water to be added to the lime-stabilized soil

[0071] Formula to be used: The mass of water to be added = the mass of wet mixture - the wet mass of stabilized soil - the wet mass of lime

[0072] Substitute: The mass of water to be added = 50-47.86-1.30 = 0.84g

[0073] Dry mix the soil with the calculated lime powder to ensure that the two are evenly mixed; add water for wet mixing to make the mixture reach the optimal moisture content; add water while stirring during the wet mixing process.

[0074] The preparation method of lime-stabilized soil with lime dosage of 4%, 6%, 8% and 10% is the same as above.

[0075] ②Prepare 5% ammonium chloride solution and 15% sodium sulfate solution:

[0076] Add 5 g of ammonium chloride granules to 95 ml of pure water, stir thoroughly with a glass rod and let stand for 30 minutes to obtain a 5% ammonium chloride solution;

[0077] Add 15 g of sodium sulfate particles to 85 ml of pure water, stir thoroughly with a glass rod and let stand for 10 minutes to obtain a sodium sulfate titration solution with a concentration of 15%;

[0078] ③Use an electronic scale to weigh 50g of the lime-stabilized soil to be tested.

[0079] ④ Add the obtained experimental lime-stabilized soil and the lime-stabilized soil to be tested into an excess of 5% ammonium chloride solution and stir rapidly.

[0080] (2) Use sodium sulfate solution to titrate the solution and detect the conductivity of the solution. Draw a graph of the relationship between the conductivity of the solution and the dosage of the titrant and determine the dosage of the titrant when the conductivity is the lowest.

[0081] ① Pour the sodium sulfate solution into the titrator and set the titrator to titrate every 2 ml;

[0082] ②After each titration, use a glass rod to stir quickly, and read the value after the solution and the reading of the benchtop conductivity meter are stable;

[0083] When the solution conductivity increases steadily, the titration volume can be increased to 5 ml each time. When the total titration volume reaches 100 ml, the operation is terminated.

[0084] ③ Draw a graph with the titration of sodium sulfate solution as the horizontal axis and the conductivity of the solution as the vertical axis;

[0085] ④ The lowest point of the image was obtained by the tangent method, and the dosage of sodium sulfate solution consumed when the image of the experimental lime-stabilized soil with lime dosages of 3%, 4%, 6%, 8%, and 10% reached the lowest point was recorded respectively.

[0086] (3) Establish the functional relationship between lime dosage and the titration of sodium sulfate solution at the lowest point, such as Figure 7 .

[0087] The obtained functional relationship is y=1.24057+0.13649*x, wherein y represents the lime dosage (%), and x represents the titration amount of the sodium sulfate solution.

[0088] (4) The lime-stabilized soil to be tested (actual lime dosage is 7%) is dissolved in ammonium chloride solution and titrated with sodium sulfate solution. The solution conductivity is lowest when 42 ml is added by experiment. According to the dosage of sodium sulfate solution consumed by the lime-stabilized soil to be tested, the lime dosage of the lime-stabilized soil to be tested is calculated by interpolation into the functional relationship:

[0089] y=1.24057+0.13649*42

[0090] y=6.99.

[0091] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for actively detecting lime dosage in lime-stabilized soil for transportation infrastructure, characterized in that: The rapid detection method comprises the following steps: S1. Prepare a 15% sodium sulfate solution as a titration solution, and prepare a 5% ammonium chloride solution for standby use, and prepare n groups of lime-stabilized soils with different lime dosages, where n≥5; S2, respectively adding n groups of lime-stabilized soil into an excess of ammonium chloride solution and stirring evenly to obtain n groups of mixed solutions; S3, using a titrator to titrate the titrant into the n groups of mixed solutions and stir evenly; S4, using a conductivity meter to test the conductivity of the n groups of mixed solutions after the titration, and recording the conductivity of each group of mixed solutions after each titration; S5, using the dosage of the consumed titrant as the abscissa and the conductivity of the mixed solution as the ordinate to draw a graph showing the relationship between the conductivity of the mixed solution and the dosage of the consumed titrant, and determining the dosage of the titrant when the conductivity is the lowest; S6. Establish a functional relationship between the lime dosage and the titration solution dosage when the conductivity is the lowest; S7. Use S2-S5 to determine the dosage of the titrant required when the conductivity of the lime-stabilized soil to be tested is the lowest, and calculate the lime dosage in combination with the functional relationship in S6.

2. The active detection technology of lime dosage in lime-stabilized soil for transportation infrastructure according to claim 1 is characterized in that: The preparation method of the lime-stabilized soil comprises the steps of dry mixing lime and soil to be stabilized to prepare a dry mixture, and then adding water to the dry mixture for wet mixing, so that the mixture reaches an optimum water content to form a wet mixture, namely, the lime-stabilized soil. The proportion calculation of each component in the wet mixture comprises the following steps: S1-1. According to the optimum moisture content of lime-stabilized soil and the mass of wet mixture, the mass calculation formula of dry mixture is as follows: In the formula: m1 is the mass of dry mixture, m2 is the mass of wet mixture, w1 is the optimum moisture content; S1-2. Determine the dry mass of the stabilized soil according to the mass of the dry mixture and the lime dosage. The calculation formulas for the dry mass of the stabilized soil and the mass of dry lime are as follows: Where: m3—dry mass of stabilized soil, m1—dry mixture mass, X i %—lime dosage; m4=m1-m3 In the formula: m4 is the mass of dry lime, m3 is the dry mass of stabilized soil, m1 is the mass of dry mixture; S1-3. According to the dry mass of the stabilized soil and the air-dried moisture content of the stabilized soil, the wet mass of the stabilized soil is calculated as follows: m5=m3*(1+w2) Where: m5 is the wet mass of the stabilized soil, m3 is the dry mass of the stabilized soil, w2 is the air-dried moisture content of the stabilized soil; S1-4, according to the dry lime mass and the air-dried moisture content of the lime, determine the wet lime mass, the wet lime mass calculation formula is as follows: m6=m4*(1+w3) m6—wet lime mass, m4—dry lime mass, w3—air-dried lime moisture content; S1-5. The formula for calculating the mass of water to be added to lime-stabilized soil is as follows: m7=m2-m5-m6 In the formula: m7 is the mass of water to be added, m2 is the mass of wet mixture, m5 is the wet mass of stabilized soil, and m6 is the mass of wet lime.

3. The method for actively detecting lime dosage in lime-stabilized soil for transportation infrastructure according to claim 2, characterized in that: The wet mixture is prepared by adding water to the dry mixture while stirring.

4. The method for actively detecting lime dosage in lime-stabilized soil for transportation infrastructure according to claim 2, characterized in that: The soil to be stabilized is construction soil that does not contain lime.

5. The method for actively detecting lime dosage in lime-stabilized soil for transportation infrastructure according to claim 1, characterized in that: In step S3, the titrator is set to titrate the solution once every 5 seconds, the titrator is set to titrate a dosage of 2-5 mL each time, and the titration termination condition is set to terminate the titration when the total titration amount is 100-200 mL.

6. The method for actively detecting lime dosage in lime-stabilized soil for transportation infrastructure according to claim 1, characterized in that: In step S4, the conductivity meter is set as follows: the measurement range is set to 0-200 ms / cm; the electrode constant is set to 10.0; and the temperature compensation knob is set to 20-25°C.

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