A rapid test method for osmotic crystallization masterbatch

Abstract

The present application relates to a kind of test methods of permeable crystallization masterbatch, in particular to a kind of test method of fast testing permeable crystallization masterbatch catalytic crystallization performance, activity, by adding liquid sodium silicate, calcium hydroxide to carry out the gelation time determination, gel amount determination and surface tension determination of permeable crystallization masterbatch.The permeable crystallization masterbatch test method, fast, 1d time can be detected result, compared with the method according to traditional GB18445-2012 "cement-based permeable crystalline waterproof material", save 87d time, and test amount is far less than traditional method;Result is accurate and reliable, and it has strong correlation with the result tested according to GB18445-2012 "cement-based permeable crystalline waterproof material" method.

Description

Technical Field

[0001] This invention relates to a testing method for permeation crystallization masterbatch, specifically a rapid testing method for testing the catalytic crystallization performance and activity of permeation crystallization masterbatch. Background Technology

[0002] Cement-based penetrating crystalline waterproofing materials are a new type of waterproofing material composed of silicate cement, quartz sand, and other base materials, mixed with active chemical substances (usually penetrating crystalline masterbatch). They can be applied as a coating or directly added to concrete as a waterproofing agent to enhance the concrete's impermeability. The penetrating crystalline masterbatch contains active materials and special catalysts; when mixed with cement, quartz sand, and other additives, it can produce a penetrating crystalline waterproofing material with high permeability and excellent self-healing ability.

[0003] This is a penetrating crystallization masterbatch containing active materials and a special catalyst. Its principle is that when mixed with water, this substance rapidly disperses into the water and then quickly disperses into the concrete, reacting with the Ca ionized in the concrete. 2+ A complexation reaction occurs, forming an unstable calcium complex. This complex diffuses through the concrete with water. When it encounters highly reactive or unhydrated cement or cement colloids, the reactive chemical substances are replaced by more stable silicate and aluminate ions, resulting in crystallization and precipitation. This forms crystals of a certain strength, blocking the capillaries. The reactive chemical substances become free radicals and continue to diffuse inward with the water. Typically, the crystals can grow to a certain size, sealing the maximum diameter of the concrete capillaries, thus making the concrete dense and waterproof.

[0004] At the same time, due to the complexation of active chemical substances with some of the Ca produced during cement hydration... 2+ When the cement hydration balance is disrupted, cement hydration is further accelerated, and some unhydrated cement rehydrates. This rehydration increases the density of the concrete, and the increased volume causes the hydration gel to crack, allowing more water to enter the unhydrated cement. This virtuous cycle produces a larger volume of gel, giving the concrete the ability to self-heal and fill cracks, thus improving the overall quality of the concrete and enhancing its resistance and durability. When the concrete is dry, the active substances are dormant due to the lack of a diffusion medium. When water seeps in, these substances are reactivated, forming new crystals that block the seepage channels, achieving a secondary waterproofing effect.

[0005] Currently, there are no specific methods or standards for testing the catalytic crystallization performance and activity of penetrating crystallization masterbatch. The usual testing method involves mixing the penetrating crystallization masterbatch with cement, quartz sand, and other additives to create a penetrating crystalline waterproofing material, and then testing it according to GB18445-2012 "Cement-based Penetrating Crystallizing Waterproofing Materials". The testing includes assessing the impermeability of mortar: 28-day impermeability pressure and 28-day impermeability pressure ratio (with coating) for coated mortar, and 28-day impermeability pressure and 28-day impermeability pressure ratio (without coating) for uncoated mortar; and the impermeability of concrete: 28-day impermeability pressure and 28-day impermeability pressure ratio (with coating) for coated concrete, and 28-day impermeability pressure and 28-day impermeability pressure ratio (without coating) for uncoated concrete, and the second impermeability pressure of coated concrete at 56 days. The 28-day impermeability pressure of the reference mortar and reference concrete should be 0.3-0.4 MPa. Including the curing time of the reference mortar and reference concrete, which is 28 days, it takes 88 days to complete all performance tests (28 days of reference specimen curing + 56 days of secondary anti-seepage waiting + 4 days of progressive pressure anti-seepage). The curing period is very long, the testing process is very complicated, and the amount of experiments is very large. 120L of concrete alone needs to be mixed.

[0006] There are many types of permeation crystallization masterbatches on the market, varying greatly in quality. Testing them according to the GB18445 method would be extremely time-consuming and costly. Therefore, there is an urgent need for a method that can quickly test the catalytic crystallization performance and activity of permeation crystallization masterbatches to rapidly determine their performance. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a rapid testing method for permeation crystallization masterbatch in order to overcome the shortcomings of the existing technology.

[0008] The technical solution adopted in this invention is: a rapid testing method for permeation crystallization masterbatch, including the determination of gelation time, gel amount, and surface tension of the permeation crystallization masterbatch.

[0009] The gelation time determination includes the following steps:

[0010] First, weigh 10.0g of the permeation crystallization masterbatch into a beaker, add 990.0g of water, stir evenly with a glass rod, and then filter through two layers of filter paper to obtain a clear liquid. Pour out three 5.0g portions from the clear liquid and put them into three 20ml graduated cylinders for later use.

[0011] The second step is to weigh 400.0g of liquid sodium silicate and mix it with 600.0g of deionized water. Stir the mixture for 30 minutes using a paint mixer to fully hydrolyze the liquid sodium silicate. Then, pour 20.0g of the fully hydrolyzed sodium silicate solution into each of the three 20ml graduated cylinders from the first step to obtain a mixture of 25.0g of clear liquid from the penetrating crystallization masterbatch and sodium silicate solution. Stir the mixture evenly with a glass rod and set it aside for later use.

[0012] The third step is to weigh out three 0.50g portions of analytical grade calcium hydroxide and pour them into three 50ml beakers respectively. Then, add 15.0g of deionized water to each of the three 50ml beakers and set aside for later use.

[0013] Fourth, under standard experimental conditions, stir the three 50ml beakers from the third step with a glass rod for 2 minutes. Then, within 30 seconds, pour 25.0g of the mixture of clear liquid from the permeation crystallization masterbatch and sodium silicate solution from the three 20ml graduated cylinders from the second step into the three 50ml beakers respectively. Start timing immediately, stir at a uniform speed for 5 minutes, and then let stand. Observe every 5 to 10 minutes.

[0014] Fifth, tilt the three 50ml beakers from the fourth step at a 45° angle. The time required for the surface to stop flowing and become completely gelled is the gelation time. The average value of the three parallel tests is used to represent the gelation time measurement result.

[0015] Furthermore, the gel volume test includes the following steps:

[0016] After observing the three 50ml beakers after completing the gelation time determination in step 5 above, if there is residual clear liquid inside, weigh the mass of the residual clear liquid m (accurate to 0.01g). Subtract the mass of the residual clear liquid from the total mass of the contents of the beaker to obtain the gel amount (40.5gm). The average value of the three parallel experiments is used to represent the gel amount determination result.

[0017] The significance of measuring gelation time and gel amount is to characterize the Ca produced by the permeation crystallization masterbatch and cement hydration. 2+ The magnitude of the complexation reaction capacity. According to the above-mentioned principle of penetrating crystallization masterbatch, the longer the gelation time, the greater the gel volume, and the better the primary and secondary waterproofing effects. The gelation time and gel volume correspond to the parameters in GB18445-2012 "Cement-based Penetrating Crystallizing Waterproofing Materials" for the 28-day waterproofing pressure and 28-day waterproofing pressure ratio (with coating) of coated mortar, and the 28-day waterproofing pressure and 28-day waterproofing pressure ratio (with coating) of coated concrete, and the second waterproofing pressure of coated concrete at 56 days. The longer the gelation time and the greater the gel volume, the higher the primary and secondary waterproofing pressures and waterproofing pressure ratios of coated mortar and concrete.

[0018] Furthermore, the surface tension measurement includes the following steps:

[0019] S1. Before measurement, thoroughly clean the platinum ring and glass of the automatic interfacial tensiometer; use anhydrous ethanol as a standard in the blank experiment to measure the surface tension, ensuring that the difference between the measured value and the theoretical value does not exceed 0.5 mN / m.

[0020] S2. Take an appropriate amount of the clear liquid after filtration of the permeation crystallization masterbatch from the first step of the gelation time determination, and determine its density ρ using a specific gravity bottle or a liquid specific gravity balance.

[0021] S3. Pour the clarified liquid from S2 into a glass beaker to a height of 20-25mm, then place the glass beaker in the center of the tray of the automatic interfacial tensiometer.

[0022] S4. Press the "Up" button on the operating interface of the automatic interfacial tensiometer. The platinum ring will then contact the clear liquid and immerse it 5-7 mm into the liquid.

[0023] S5. Press the "Stop" button on the operation interface of the automatic interfacial tensiometer, then press the "Lower" button. The tray and clear liquid will begin to descend.

[0024] S6. Continue until the platinum ring detaches from the surface of the clear liquid, and record the maximum value P displayed on the automatic interfacial tensiometer.

[0025] S7. Repeat the above process three times, and use the average value of the three tests to represent the result of the surface tension σ measurement.

[0026] Furthermore, in the second step of the gelation time test, the liquid sodium silicate has a modulus of 2.4 and a Baume degree of 51.

[0027] Furthermore, in the surface tension measurement, the surface tension σ = F * P, where σ is the surface tension of the solution, in mN / m; P is the maximum value of the display, in mN / m; and F is the correction factor.

[0028] Furthermore, the formula for calculating the correction factor is as follows:

[0029] in,

[0030] C – Circumference of the platinum ring 2πR, in centimeters (cm);

[0031] R – the sum of the inner radius of the platinum ring and the radius of the platinum wire, in centimeters (cm);

[0032] ρ ０ —Air density, expressed in grams per milliliter (g / mL);

[0033] ρ—Density of the solution being tested, in grams per milliliter (g / mL);

[0034] r – radius of the platinum wire, in centimeters (cm).

[0035] A lower surface tension value indicates a stronger penetrating ability of the penetrating crystalline masterbatch, allowing it to penetrate deeper into the concrete to participate in the reaction. The surface tension parameters correspond to the parameters in GB18445-2012 "Cement-Based Penetrating Crystalline Waterproofing Materials" for the following: 28-day seepage pressure and 28-day seepage pressure ratio (with coating) for coated mortar; 28-day seepage pressure and 28-day seepage pressure ratio (without coating) for uncoated mortar; and 28-day seepage pressure and 28-day seepage pressure ratio (with coating) for coated concrete; 28-day seepage pressure and 28-day seepage pressure ratio (without coating) for uncoated concrete; and the second seepage pressure of coated concrete at 56 days. Lower surface tension corresponds to higher first and second seepage pressures and seepage pressure ratios for coated and uncoated mortar and concrete.

[0036] The present invention has the following advantages over the prior art:

[0037] 1. Fast speed: test results can be obtained in 1 day, saving 87 days compared to the traditional method of GB18445-2012 "Cement-based Penetrating Crystalline Waterproofing Materials", and the number of tests is much smaller than that of the traditional method;

[0038] 2. The results are accurate and reliable, and have a strong correlation with the results tested according to the method in GB18445-2012 "Cement-based Penetrating Crystalline Waterproofing Materials". Detailed Implementation

[0039] The embodiments of the present invention are described in detail below. The embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0040] Example 1

[0041] The gelation time determination includes the following steps:

[0042] First, weigh 10.0g of a sample of permeation crystallization masterbatch from a manufacturer in Nantong and put it into a beaker. Add 990.0g of water, stir evenly with a glass rod, and then filter it through two layers of filter paper to obtain a clear liquid. Pour out three 5.0g portions from the clear liquid and put them into three 20ml graduated cylinders for later use.

[0043] The second step involves weighing 400.0g of liquid sodium silicate with a modulus of 2.4 and a Baume degree of 51, mixing it with 600.0g of deionized water, and stirring it with a paint mixer for 30 minutes to fully hydrolyze the liquid sodium silicate. Then, pour 20.0g of the fully hydrolyzed sodium silicate solution into each of the three 20ml graduated cylinders from the first step to obtain a mixture of 25.0g of clear liquid from the penetrating crystallization masterbatch and sodium silicate solution. Stir the mixture evenly with a glass rod and set it aside for later use.

[0044] The third step is to weigh out three 0.50g portions of analytical grade calcium hydroxide and pour them into three 50ml beakers respectively. Then, add 15.0g of deionized water to each of the three 50ml beakers and set aside for later use.

[0045] Fourth, under standard experimental conditions, stir the three 50ml beakers from the third step with a glass rod for 2 minutes. Then, within 30 seconds, pour 25.0g of the mixture of clear liquid from the permeation crystallization masterbatch and sodium silicate solution from the three 20ml graduated cylinders from the second step into the three 50ml beakers respectively. Start timing immediately, stir at a uniform speed for 5 minutes, and then let stand. Observe every 5 to 10 minutes.

[0046] Fifth, tilt the three 50ml beakers from the fourth step at a 45° angle. The time required for the surface to stop flowing and become completely gelled is the gelation time. The average value of the three parallel tests is used to represent the gelation time measurement result.

[0047] The gel volume test includes the following steps:

[0048] After observing the three 50ml beakers after completing the gelation time determination in step 5 above, if there is residual clear liquid inside, weigh the mass of the residual clear liquid m (accurate to 0.01g). Subtract the mass of the residual clear liquid from the total mass of the contents of the beaker to obtain the gel amount (40.5gm). The average value of the three parallel experiments is used to represent the gel amount determination result.

[0049] Surface tension measurement includes the following steps:

[0050] S1. Before measurement, thoroughly clean the platinum ring and glass of the automatic interfacial tensiometer; use anhydrous ethanol as a standard in the blank experiment to measure the surface tension, ensuring that the difference between the measured value and the theoretical value does not exceed 0.5 mN / m.

[0051] S2. Take an appropriate amount of the clear liquid after filtration of the permeation crystallization masterbatch from the first step of the gelation time determination, and determine its density ρ using a specific gravity bottle or a liquid specific gravity balance.

[0052] S3. Pour the clarified liquid from S2 into a glass beaker to a height of 20-25mm, then place the glass beaker in the center of the tray of the automatic interfacial tensiometer.

[0053] S4. Press the "Up" button on the operating interface of the automatic interfacial tensiometer. The platinum ring will then contact the clear liquid and immerse it 5-7 mm into the liquid.

[0054] S5. Press the "Stop" button on the operation interface of the automatic interfacial tensiometer, then press the "Lower" button. The tray and clear liquid will begin to descend.

[0055] S6. Continue until the platinum ring detaches from the surface of the clear liquid, and record the maximum value P displayed on the automatic interfacial tensiometer.

[0056] S7. Repeat the above process three times, and use the average value of the three tests to represent the result of the surface tension σ measurement.

[0057] In surface tension measurement, surface tension σ = F * P, where σ is the surface tension of the solution in mN / m; P is the maximum value displayed on the monitor in mN / m; and F is the correction factor.

[0058] The formula for calculating the correction factor is as follows:

[0059] in,

[0060] C – Circumference of the platinum ring 2πR, in centimeters (cm);

[0061] R – the sum of the inner radius of the platinum ring and the radius of the platinum wire, in centimeters (cm);

[0062] ρ ０ —Air density, expressed in grams per milliliter (g / mL);

[0063] ρ—Density of the solution being tested, in grams per milliliter (g / mL);

[0064] r – radius of the platinum wire, in centimeters (cm).

[0065] A penetrating crystalline waterproofing material was prepared by mixing 50.0% of 425 cement, 2.0% of penetrating crystalline masterbatch from a manufacturer in Nantong, 38.0% of quartz sand, 5.0% of fly ash, and 5.0% of calcite powder. Tests were conducted according to GB18445-2012 "Cement-based Penetrating Crystalline Waterproofing Materials" to obtain the 28-day seepage pressure, 28-day seepage pressure ratio (with coating), and 28-day seepage pressure and 28-day seepage pressure ratio (without coating) of the coated mortar. The concrete seepage resistance performance was also assessed, including the 28-day seepage pressure, 28-day seepage pressure ratio (with coating), and 28-day seepage pressure and 28-day seepage pressure ratio (without coating) of the coated concrete, and the second seepage pressure of the coated concrete at 56 days.

[0066] Example 2

[0067] The difference from Example 1 is that a sample of permeation crystallization masterbatch from a manufacturer in Suzhou was selected.

[0068] Example 3

[0069] The difference from Example 1 is that a sample of permeation crystallization masterbatch from a manufacturer in Shanghai was selected.

[0070] Example 4

[0071] The difference from Example 1 is that a sample of permeation crystallization masterbatch from a manufacturer in Shijiazhuang was selected.

[0072] Example 5

[0073] The difference from Example 1 is that a sample of permeation crystallization masterbatch from a manufacturer in Yancheng was selected.

[0074] Comparative Example 1

[0075] This comparative example is a sample of cement-based penetrating crystalline waterproofing material prepared from penetrating crystalline masterbatch, whose test data are exactly equal to the qualified standard, verified by the GB18445-2012 "Cement-based Penetrating Crystalline Waterproofing Materials" method during the exploratory experiment. The gelation time, gel amount and surface tension were tested by the GB18445-2012 "Cement-based Penetrating Crystalline Waterproofing Materials" method and the method of this invention, respectively.

[0076] Comparative Example 2

[0077] The difference from Examples 1-5 and Comparative Example 1 is that in the gelation time determination, in the second step, 600.0g of liquid sodium silicate was weighed and mixed with 400.0g of deionized water.

[0078] Comparative Example 3

[0079] The difference from Examples 1-5 and Comparative Example 1 is that in the gelation time determination, in the second step, 300.0g of liquid sodium silicate was weighed and mixed with 700.0g of deionized water.

[0080] The performance of Examples 1-5 and Comparative Example 1 of this invention, measured according to the method of GB18445-2012, is shown in Table 1:

[0081] Table 1

[0082]

[0083]

[0084] The performance of Examples 1-5 and Comparative Example 1 obtained according to the rapid testing method of the present invention is shown in Table 2:

[0085] Table 2

[0086]

[0087] The performance of Examples 1-5 and Comparative Example 1, measured according to the modified test method in Comparative Example 2, is shown in Table 3:

[0088] Table 3

[0089]

[0090] The performance of Examples 1, 2, 3, 4, and 5 of the present invention and Comparative Example 1, measured according to the modified test method in Comparative Example 3 of the present invention, is shown in Table 4:

[0091] Table 4

[0092]

[0093] A comparison of the data in Tables 1 and 2 shows that, according to the GB18445-2012 test method, the performance of Examples 1 and 2 is unqualified; similarly, their gelation time and gel amount are also lower than the corresponding data of Comparative Example 6. Comparative Example 6 is a standard sample, and all its test data are exactly equal to the qualified standard obtained according to the GB18445-2012 test method.

[0094] Furthermore, a comparison of the data in Tables 1 and 2 shows that the performance measured in Examples 3, 4, and 5 is qualified and exceeds the requirements of GB18445-2012 standard; similarly, their gelation time and gel amount are also higher than the corresponding data in Comparative Example 6. Therefore, the data of Comparative Example 1, measured according to the method of testing the performance of the permeation crystallization masterbatch according to the present invention, can be used as the qualified standard, namely: gelation time ≥ 30 min, gel amount = 40.50 g, and surface tension ≤ 36 mN / m.

[0095] However, in Comparative Examples 2 and 3, after changing the solubility of the sodium silicate solution used in the third step of this invention or replacing it with a silica sol solution, the data in Table 3 shows that, according to the GB18445-2012 test method, the permeation crystallization masterbatch of Example 2 is unqualified, but the tested gelation time is the same as that of Comparative Example 1. Furthermore, the permeation crystallization masterbatches of Examples 1 and 2 are unqualified, but in terms of gelation amount, they are the same as those of the qualified product Comparative Example 1 and Examples 3-5 which exceed the qualified product standard, making it impossible to distinguish between qualified and unqualified products. The data in Table 4 shows that the gelation time of the qualified product is 90 minutes, but the gelation times of the unqualified products Example 1, Example 2, and Examples 3-5 (which exceed the qualified product standard) are all greater than 90 minutes, making it impossible to distinguish between qualified and unqualified products.

[0096] In conclusion, we can see that the method of this invention for testing the catalytic crystallization performance and activity of permeation crystallization masterbatch is feasible, scientific, and effective, and is faster and more efficient than the test method in GB18445-2012.

Claims

1. A rapid testing method for permeation crystallization masterbatch, characterized in that, This includes the determination of gelation time, gel amount, and surface tension of the permeation crystallization masterbatch. The gelation time determination includes the following steps: First, weigh 10.0g of the permeation crystallization masterbatch into a beaker, add 990.0g of water, stir evenly with a glass rod, and then filter through two layers of filter paper to obtain a clear liquid. Pour out three 5.0g portions from the clear liquid and put them into three 20ml graduated cylinders for later use. The second step is to weigh 400.0g of liquid sodium silicate and mix it with 600.0g of deionized water. Stir the mixture for 30 minutes using a paint mixer to fully hydrolyze the liquid sodium silicate. Then, pour 20.0g of the fully hydrolyzed sodium silicate solution into each of the three 20ml graduated cylinders from the first step to obtain a mixture of 25.0g of clear liquid from the penetrating crystallization masterbatch and sodium silicate solution. Stir the mixture evenly with a glass rod and set it aside for later use. The third step is to weigh out three 0.50g portions of analytical grade calcium hydroxide and pour them into three 50ml beakers respectively. Then, add 15.0g of deionized water to each of the three 50ml beakers and set aside for later use. Fourth, under standard experimental conditions, stir the three 50ml beakers from the third step with a glass rod for 2 minutes. Then, within 30 seconds, pour 25.0g of the mixture of clear liquid from the permeation crystallization masterbatch and sodium silicate solution from the three 20ml graduated cylinders from the second step into the three 50ml beakers respectively. Start timing immediately, stir at a uniform speed for 5 minutes, and then let stand. Observe every 5 to 10 minutes. Fifth, tilt the three 50ml beakers from the fourth step at a 45° angle. The time required for the surface to stop flowing and become completely gelled is the gelation time. The average value of the three parallel tests is used to represent the gelation time measurement result.

2. The rapid testing method for permeation crystallization masterbatch according to claim 1, characterized in that, The gel volume test includes the following steps: After observing the three 50ml beakers after completing the gelation time determination in step 5 above, if there is residual clear liquid inside, weigh the mass of the residual clear liquid m (accurate to 0.01g). Subtract the mass of the residual clear liquid from the total mass of the contents of the beaker to obtain the gel amount (40.5gm). The average value of the three parallel experiments is used to represent the gel amount determination result.

3. The rapid testing method for permeation crystallization masterbatch according to claim 1, characterized in that, The surface tension measurement includes the following steps: S1. Before measurement, thoroughly clean the platinum ring and glass of the automatic interfacial tensiometer; use anhydrous ethanol as a standard in the blank experiment to measure the surface tension, ensuring that the difference between the measured value and the theoretical value does not exceed 0.5 mN / m. S2. Take an appropriate amount of the clear liquid after filtration of the permeation crystallization masterbatch from the first step of the gelation time determination, and determine its density ρ using a specific gravity bottle or a liquid specific gravity balance. S3. Pour the clarified liquid from S2 into a glass beaker to a height of 20-25mm, then place the glass beaker in the center of the tray of the automatic interfacial tensiometer. S4. Press the "Up" button on the operating interface of the automatic interfacial tensiometer. The platinum ring will then contact the clear liquid and immerse it 5-7 mm into the liquid. S5. Press the "Stop" button on the operating interface of the automatic interfacial tensiometer, then press the "Lower" button. The tray and clear liquid will begin to descend. S6. Continue until the platinum ring detaches from the surface of the clear liquid, and record the maximum value P displayed on the automatic interfacial tensiometer. S7. Repeat the above process three times, and use the average value of the three tests to represent the result of the surface tension σ measurement.

4. The rapid testing method for permeation crystallization masterbatch according to claim 1, characterized in that, In the second step of the gelation time test, the liquid sodium silicate had a modulus of 2.4 and a Baume degree of 51.

5. The rapid testing method for permeation crystallization masterbatch according to claim 3, characterized in that, In surface tension measurement, the surface tension σ = F * P, where σ is the surface tension of the solution in mN / m; P is the maximum value displayed on the monitor in mN / m; and F is the correction factor.

6. The rapid testing method for permeation crystallization masterbatch according to claim 5, characterized in that, The formula for calculating the correction factor is as follows: in, C – Circumference of the platinum ring 2πR, in centimeters (cm); R – the sum of the inner radius of the platinum ring and the radius of the platinum wire, in centimeters (cm); ρ0 — air density, in grams per milliliter (g / mL); ρ—Density of the solution being tested, in grams per milliliter (g / mL); r – radius of the platinum wire, in centimeters (cm).

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