CN111751305A - Method for measuring contents of cement and mineral powder in hardened concrete - Google Patents
Method for measuring contents of cement and mineral powder in hardened concrete Download PDFInfo
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- 239000004568 cement Substances 0.000 title claims abstract description 62
- 239000004567 concrete Substances 0.000 title claims abstract description 56
- 229910052500 inorganic mineral Inorganic materials 0.000 title claims abstract description 43
- 239000011707 mineral Substances 0.000 title claims abstract description 43
- 239000000843 powder Substances 0.000 title claims abstract description 43
- 238000000034 method Methods 0.000 title claims abstract description 34
- 239000004570 mortar (masonry) Substances 0.000 claims abstract description 88
- 238000005259 measurement Methods 0.000 claims abstract description 8
- 238000005070 sampling Methods 0.000 claims abstract description 6
- 235000010755 mineral Nutrition 0.000 claims description 39
- 239000000243 solution Substances 0.000 claims description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 24
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 20
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 12
- 238000005303 weighing Methods 0.000 claims description 12
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 9
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 7
- 238000001914 filtration Methods 0.000 claims description 7
- 238000002156 mixing Methods 0.000 claims description 7
- 238000002791 soaking Methods 0.000 claims description 7
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims description 6
- 238000002835 absorbance Methods 0.000 claims description 6
- 239000000706 filtrate Substances 0.000 claims description 6
- 238000005406 washing Methods 0.000 claims description 6
- 238000005553 drilling Methods 0.000 claims description 5
- 238000005520 cutting process Methods 0.000 claims description 4
- 239000012153 distilled water Substances 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- 238000003756 stirring Methods 0.000 claims description 4
- 239000011609 ammonium molybdate Substances 0.000 claims description 3
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 claims description 3
- 229940010552 ammonium molybdate Drugs 0.000 claims description 3
- 235000018660 ammonium molybdate Nutrition 0.000 claims description 3
- 229960005070 ascorbic acid Drugs 0.000 claims description 3
- 235000010323 ascorbic acid Nutrition 0.000 claims description 3
- 239000011668 ascorbic acid Substances 0.000 claims description 3
- 238000007664 blowing Methods 0.000 claims description 3
- 238000007865 diluting Methods 0.000 claims description 3
- 230000007935 neutral effect Effects 0.000 claims description 3
- 239000000377 silicon dioxide Substances 0.000 claims description 3
- 239000012086 standard solution Substances 0.000 claims description 3
- 238000000227 grinding Methods 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims description 2
- 235000012239 silicon dioxide Nutrition 0.000 claims description 2
- 238000012360 testing method Methods 0.000 abstract description 17
- 239000002994 raw material Substances 0.000 abstract description 7
- 239000010881 fly ash Substances 0.000 abstract description 6
- 239000000463 material Substances 0.000 abstract description 6
- 239000004576 sand Substances 0.000 abstract description 4
- 239000012615 aggregate Substances 0.000 abstract description 2
- 238000000926 separation method Methods 0.000 abstract 1
- 230000006872 improvement Effects 0.000 description 4
- 238000010276 construction Methods 0.000 description 3
- 230000036571 hydration Effects 0.000 description 3
- 238000006703 hydration reaction Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000011481 absorbance measurement Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- SESFRYSPDFLNCH-UHFFFAOYSA-N benzyl benzoate Chemical compound C=1C=CC=CC=1C(=O)OCC1=CC=CC=C1 SESFRYSPDFLNCH-UHFFFAOYSA-N 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000001612 separation test Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Sampling And Sample Adjustment (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
The invention relates to a method for measuring the contents of cement and mineral powder in hardened concrete, which is suitable for the hardened concrete with natural sand as fine aggregate and cement, fly ash and mineral powder as cementing materials, and the age of the concrete is not more than 1 year; according to the invention, through the sampling step and the coarse aggregate and mortar separation step, the mortar content in the hardened concrete and the cement and mineral powder content in the mortar are calculated. The method has high accuracy of the measurement result, the absolute value of the relative error of the measurement result of the hardened concrete within 1 year of age is within 10 percent, only raw material cement is needed to be provided, the threshold meeting the test condition is reduced, and the method is easy to operate and popularize.
Description
Technical Field
The invention relates to a method for measuring the contents of cement and mineral powder in hardened concrete, belonging to the technical field of building material detection.
Background
At present, chemical analysis is the most effective and easy-to-popularize method for determining the content of cementitious materials in hardened concrete. The method mainly comprises the steps of firstly crushing hardened concrete integrally, then measuring, and finally correcting a result by using coarse aggregate and fine aggregate, wherein the process is complicated, and the error is large (mainly the influence of the coarse aggregate on a test result, and the absolute value of the relative error is usually more than 10%); the test requires harsh conditions, and in addition to providing raw material cement, if concrete is added with active admixture, each active admixture is also provided for the test.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a method for measuring the contents of cement and mineral powder in hardened concrete, and the specific technical scheme is as follows:
a method for measuring the contents of cement and mineral powder in hardened concrete comprises the following steps:
step one, sampling
Sampling by adopting a core drilling method, cutting and grinding two ends of a retrieved core sample to obtain a sample, and measuring the volume vi of the sample;
step two, separating the coarse aggregate from the mortar
Baking the sample to constant weight at 105 +/-5 ℃, wherein the mass of the dried sample is mi; putting the dried sample into a high-temperature furnace, heating to 520 +/-10 ℃ at the speed of about 10 ℃/min, preserving the heat for 1h at the temperature of 520 +/-10 ℃, cooling to room temperature in the air to obtain a dry sample, crushing the dry sample, separating coarse aggregate and mortar by using a 2.5mm square-hole sieve, weighing and separating the coarse aggregate with the mass of mciThe mass of the separated mortar is msi，msi＝mi-mci；
Step three, quality of the mortar without the bound water
Get ifDry-mixing the mortar separated in the second step, wherein the mass of each part of the mortar is m0Burning the mixture for 1h at the temperature of 520 +/-10 ℃ to obtain burning mortar, then putting the burning mortar into a drier, cooling the burning mortar to room temperature, and weighing the burning mortar with the mass m1The mass loss of the mortar after burning for 2 hours in the environment of 520 +/-10 ℃ is w,
the arithmetic mean value of w is the mass loss of the 105 ℃ dried mortar at 520 ℃;
the mass of the mortar not containing bound water in each core sample was ms，ms＝msi×(1-w)；
Step four, sample pretreatment
Picking out mortar without coarse aggregate from the hardened concrete cut off in the cutting process of the core sample, soaking the mortar by absolute ethyl alcohol, blowing air at the temperature of 60 ℃ for 24 hours to enable the mortar to pass through a 0.6mm square-hole sieve, putting the mortar into a high-temperature furnace, keeping the mortar at the temperature of 520 +/-10 ℃ for 2 hours, and cooling the mortar to room temperature in a dryer to obtain a mortar sample;
preparing a silicon dioxide standard solution according to a method of 6.1.72 in GB/T176-2017, and drawing a working curve;
weighing 1.5 +/-0.1 g of mortar sample, weighing 0.2 +/-0.05 g of cement sample (for preparing cement for hardening concrete), putting the weighed mortar sample into a beaker, pouring 100mL of hydrochloric acid solution with the temperature of 3-5 ℃, wherein the volume fraction of the hydrochloric acid solution is 25%, stirring for 20min in the environment of 3-5 ℃, filtering by using medium-speed filter paper X, washing at least twice by using 50 ℃ hot water, then transferring the medium-speed filter paper X and filter residues into a plastic beaker, pouring 75mL of NaOH solution with the temperature of 50 ℃ and the concentration of 10g/L, putting into a 50 ℃ water bath for 15min, filtering by using medium-speed filter paper Y, washing by using 50 ℃ hot water until the filtrate is neutral, finally collecting all filtrates, and fixing the volume to 500mL to obtain solution B;
step five, soluble SiO in the mortar2Content (wt.)
Putting the solution B into a volumetric flask, adding water to dilute the solution B to 40mL, sequentially adding 5.0mL of hydrochloric acid solution with the volume fraction of 9%, 8.0mL of absolute ethyl alcohol and 6.0mL of ammonium molybdate solution with the concentration of 50g/L, uniformly mixing, standing for 30min, sequentially adding 20mL of hydrochloric acid solution with the volume fraction of 50% and 5.0mL of ascorbic acid solution with the concentration of 5g/L, finally diluting to 100mL by using distilled water, shaking up, standing for 60min, and measuring the absorbance at 660mm by using a spectrophotometer;
soluble SiO in mortar or cement samples2The content is C, and the unit is%;
wherein c is soluble SiO in the solution in the volumetric flask2The content is found in a working curve according to the absorbance, and the unit is mu g/mL; m is the mass of the mortar sample or the cement sample, and the unit is g; v is the volume of the solution B to be detected, and the unit is mL;
step six, the content of cement and mineral powder in the mortar
C3The content of cement and mineral powder in the mortar sample is shown in unit; c1Is soluble SiO in mortar sample2Content, in%; c2Is soluble SiO in cement sample2Content, unit%;
seventhly, the content of cement and mineral powder in the hardened concrete
The content of cement and mineral powder in the core sample is Hi，
As an improvement of the technical scheme, in the step one, the diameter of a core sample obtained by adopting a core drilling method is more than or equal to 3 times of the particle size of the coarse aggregate.
As an improvement of the above technical solution, in the step one, the mass of each core sample obtained is greater than or equal to 2 kg; the cores are taken at least 5 different parts of the concrete of the same batch, and the total mass of the core sample is not less than 10 kg.
As an improvement of the technical scheme, in the fourth step, absolute ethyl alcohol is adopted for soaking treatment, the soaking time is 24 hours, and the absolute ethyl alcohol is replaced once every 12 hours.
The invention has the beneficial effects that:
the method for measuring the contents of cement and mineral powder in the hardened concrete is suitable for the hardened concrete with natural sand as fine aggregate and cement, fly ash and mineral powder as cementing materials, and the age of the concrete is not more than 1 year; the method has high accuracy of the measurement result, the absolute value of the relative error of the measurement result of the hardened concrete within 1 year of age is within 10 percent, only raw material cement is needed to be provided, the threshold meeting the test condition is reduced, and the method is easy to operate and popularize.
Drawings
FIG. 1 is a diagram of a concrete sample C60 according to the present invention;
FIG. 2 is a pictorial view of nine core samples examined in example 3.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
First, the main steps and parameters of the method
1. Sampling
The core drilling method (the diameter of the core sample is generally not less than 3 times of the particle size of the coarse aggregate) is easy to sample, each core sample is a single whole and has no appearance defect, the mass of each core sample is generally not less than 2kg, the cores are taken at least at 5 different parts of the same batch of concrete, and the total mass of the core samples is not less than 10 kg; the retrieved core sample is cut at both ends, ground flat and its volume v is measuredi(unit mm)3)。
2. Separating coarse aggregate from mortar
Based on the elastic theory and the interface transition region theory, the mixture is dried at the temperature of 105 +/-5 DEG CTo constant weight of the sample (mass m)iUnit g) is put into a high temperature furnace, the temperature is raised to 520 ℃ +/-10 ℃ at the speed of about 10 ℃/min, the temperature is kept for 1h, then the air is cooled to room temperature, the whole is crushed by slight mechanical force (the particle size is based on that the shape of the coarse aggregate is not damaged), the coarse aggregate and the mortar are separated by a 2.5mm square-hole sieve, and the mass m of the separated coarse aggregate is weighedci(unit g), the mass of the mortar separated is msi(unit g) of the total amount of the organic solvent,
msi＝mi-mci。
3. mortar content in hardened concrete
(1) Quality of mortar without bound water
5 parts of the mortar separated previously were taken, each of which was about 5g (in m)0Accurate to 0.0001g), burning for 1h in the environment of 520 +/-10 ℃ (equivalent to mortar co-burning for 2h), then putting into a drier to cool to room temperature, weighing, and counting as m1Calculating the mass loss of the mortar burned for 2 hours at the temperature of 520 +/-10 ℃ as w (unit is percent), removing the maximum value and the minimum value, wherein the arithmetic mean value of the three intermediate values is the mass loss of the mortar baked to constant weight at the temperature of 105 ℃;
(2) hardened concrete medium mortar (Sand + cementing material)
Calculating the mass m of the mortar without the binding water in each core samples，
ms＝msi×(1-w)；
In the formula: m issThe mass of the mortar without bound water is given in g.
4. Cement and mineral powder content in mortar
(1) Sample pretreatment
Selecting mortar without coarse aggregate from the hardened concrete cut from the processed sample, soaking the sample by absolute ethyl alcohol (the content is more than or equal to 99.5 percent) for 24 hours, changing the absolute ethyl alcohol once when the absolute ethyl alcohol is used for 12 hours, blowing air for 24 hours at the temperature of 60 ℃ to ensure that the sample passes through a 0.6mm square hole sieve, putting the sample into a high-temperature furnace, keeping the temperature for 2 hours within the range of 520 +/-10 ℃, and cooling the sample to the room temperature in a dryer to obtain the mortar sample for later use.
(2) Silica (SiO) was formulated according to the method of 6.1.72 in GB/T176-20172) And (5) standard solution, and drawing a working curve.
(3) Sample dissolution
Weighing 1.5 +/-0.1 g of the mortar sample, and accurately weighing the mortar sample to 0.0001 g; weighing 0.2 +/-0.05 g of a cement sample (for preparing the cement for hardening concrete) to be accurate to 0.0001 g; putting the weighed mortar sample into a 250mL beaker, pouring 100mL of hydrochloric acid solution with volume fraction of 25% and temperature of 3-5 ℃, stirring for 20min at the temperature of 3-5 ℃, filtering in a Buchner funnel by filling two layers of medium-speed filter paper X, washing at least twice with 50 ℃ hot water, transferring all the medium-speed filter paper X and filter residues into a plastic beaker, pouring 75mL of NaOH solution with concentration of 10g/L at 50 ℃, putting in a 50 ℃ water bath for 15min (stirring at intervals to crush the medium-speed filter paper X), filtering in a Buchner funnel by filling 2 layers of medium-speed filter paper Y, washing with 50 ℃ hot water until the filtrate is neutral, finally collecting all the filtrates, and fixing the volume to 500mL to obtain a solution B.
(4) Soluble SiO in mortar2Content (wt.)
A certain amount of solution B (1.00 mL of the solution prepared from the mortar sample or the cement sample) was taken in a 100mL volumetric flask and absorbance measurement was carried out. The method comprises the following specific steps: adding water into a volumetric flask to dilute the solution to 40mL, sequentially adding 5.0mL of hydrochloric acid solution with volume fraction of 9%, 8.0mL of absolute ethyl alcohol and 6.0mL of ammonium molybdate solution (with concentration of 50g/L and validity period of 7d, filtering is better when preparing), uniformly mixing, standing for 30min, sequentially adding 20mL of hydrochloric acid solution with volume fraction of 50% and 5.0mL of ascorbic acid solution (with concentration of 5g/L and ready-to-use), finally diluting to 100mL with distilled water, shaking up, standing for 60min, and measuring the absorbance at 660mm by using a spectrophotometer (10mm cuvette, using distilled water as reference).
Calculating soluble SiO in mortar and cement samples2Content, two tests were performed on each sample and the average was taken.
In the formula: c is soluble SiO in mortar sample or cement sample2Content,%; c is soluble SiO in 100mL volumetric flask solution2Content (found in the working curve according to absorbance), μ g/mL; m is the mass of the mortar sample or the cement sample, and the unit is g; v is the volume of solution B to be tested extracted in mL.
(5) Cement and mineral powder content in mortar
And calculating the content of cement and mineral powder in the mortar sample.
C3The content of cement and mineral powder in the mortar sample is shown in unit; c1Is soluble SiO in mortar2Content, in%; c2Is soluble SiO in cement2The content is expressed in%.
5. Cement and mineral powder content in hardened concrete
The content of cement and mineral powder in a single hardened concrete core sample is Hi，
In the formula: hiThe content of cement and mineral powder in a single hardened concrete core sample is kg/m3. Respectively calculating the content of cement and mineral powder in each concrete core sample (at least 5), removing the maximum value and the minimum value, taking the arithmetic average value of the intermediate values, and obtaining the result accurate to 1kg/m3。
Example 2
The content of cement and mineral powder in the hardened concrete is accurately measured, so that the absolute value of the relative error of the measurement result of the content of the cement and the mineral powder in the hardened concrete is controlled within 10 percent, and the test time is about 7 days.
Example verification:
(1) a commercial concrete company in Bengal City, formed C60 concrete in two groups (6 blocks), with sample sizes of 150mm by 150mm (as shown in FIG. 1) and a molding date of 2018, 6 months and 1 day, as shown in Table 1. (the test work begins in 2018, 12 and 3 months, core processing is firstly carried out, then part of hardened concrete is extracted, sample pretreatment is carried out in 2018, 12 and 19 months, and finally the treated sample is subjected to test analysis of the content of cement and mineral powder.)
TABLE 1C 60 concrete mix proportion (water unknown) (kg/m)3)
The content of cement and mineral powder in the C60 concrete test block is measured (479 kg/m)3) To theoretical value (494 kg/m)3) The difference is 15kg/m3The absolute value of the relative error was 3.04%. The theoretical value is calculated by the cement content and the mineral powder content in the mix proportion in the table 1.
Example 3
The strength of part of C45 concrete is found to be smaller than the design value during construction of a certain project in Maanshan, corresponding technical data are provided for the next process of the project in order to solve the generation reason, a construction unit drills 9 core samples (with the diameter of 100mm and the length of 150-200 mm, as shown in figure 2) from the site, and the unit is entrusted to carry out test analysis on the content of cement and mineral powder in hardened concrete.
The mix ratio of the concrete C45 in the construction is shown in Table 2 (a concrete mix ratio notice extracted from a laboratory of the corresponding concrete products Co., Ltd.).
TABLE 2C 45 concrete mixing ratio (kg/m)3)
The test work starts in 12 and 3 months in 2018, the core sample is processed, then part of hardened concrete is extracted, sample pretreatment is carried out in 19 days in 12 and 19 months in 2018, and finally the treated sample is subjected to test analysis on the total content of cement and mineral powder.
Test results (490 kg/m)3) To theoretical value (460 kg/m)3) With a difference of 30kg/m3The cement and mineral powder in the mixing ratio with concreteThe absolute value of the relative error of the contents was 6.52%. The theoretical value is calculated by the cement content and the mineral powder content in the mix proportion in the table 2.
In the above examples, the concentration unit is g/L which means a mass-volume concentration, for example, 1g/L means a solution in which 1g of solute is dissolved in 1L.
The method has high accuracy of the measurement result (the absolute value of the relative error of the measurement result of the hardened concrete within 1 year of age is within 10 percent), reduces the threshold (only raw material cement needs to be provided) meeting the test conditions, and is easy to operate and popularize.
According to the invention, through a separation test of the coarse aggregate and the mortar, the influence of the coarse aggregate on a test result is reduced to the minimum, and raw material coarse aggregate is not needed; by controlling the concentration, temperature and reaction conditions of the acid liquor, the influence of the fine aggregate on the test result is reduced to the minimum, and raw material fine aggregate is not required to be provided; meanwhile, the method solves the problem of measuring the content of coarse aggregate and mortar for the reverse thrust of the mixing proportion in the hardened concrete, and lays a foundation for measuring the content of each cementing material in the later period.
Aiming at the secondary hydration phenomenon of the active admixture in concrete, the hydration of cement, mineral powder and fly ash is calculated uniformly by utilizing the secondary hydration of the mineral powder and the fly ash, so that a good effect is obtained, and the embarrassment that the raw materials of the cement, the mineral powder and the fly ash must be provided at the same time is avoided.
The invention is suitable for hardened concrete (the age is not more than 1 year) with fine aggregate being natural sand and cementing material being cement, fly ash and mineral powder.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (4)
1. A method for measuring the contents of cement and mineral powder in hardened concrete is characterized by comprising the following steps:
step one, sampling
Sampling by drilling core method, cutting and grinding two ends of the core sample to obtain sample, and measuringVolume v of the measurement samplei；
Step two, separating the coarse aggregate from the mortar
Baking the sample to constant weight at 105 +/-5 ℃, wherein the mass of the dried sample is mi(ii) a Putting the dried sample into a high-temperature furnace, heating to 520 +/-10 ℃ at the speed of about 10 ℃/min, preserving the heat for 1h at the temperature of 520 +/-10 ℃, cooling to room temperature in the air to obtain a dry sample, crushing the dry sample, separating coarse aggregate and mortar by using a 2.5mm square-hole sieve, weighing and separating the coarse aggregate with the mass of mciThe mass of the separated mortar is msi，msi＝mi-mci；
Step three, quality of the mortar without the bound water
Taking a plurality of parts of mortar separated in the second step, wherein the mass of each part of mortar is m0Burning the mixture for 1h at the temperature of 520 +/-10 ℃ to obtain burning mortar, then putting the burning mortar into a drier, cooling the burning mortar to room temperature, and weighing the burning mortar with the mass m1The mass loss of the mortar after burning for 2 hours in the environment of 520 +/-10 ℃ is w,
the arithmetic mean value of w is the mass loss of the 105 ℃ dried mortar at 520 ℃;
the mass of the mortar not containing bound water in each core sample was ms，ms＝msi×(1-w)；
Step four, sample pretreatment
Picking out mortar without coarse aggregate from the hardened concrete cut off in the cutting process of the core sample, soaking the mortar by absolute ethyl alcohol, blowing air at the temperature of 60 ℃ for 24 hours to enable the mortar to pass through a 0.6mm square-hole sieve, putting the mortar into a high-temperature furnace, keeping the mortar at the temperature of 520 +/-10 ℃ for 2 hours, and cooling the mortar to room temperature in a dryer to obtain a mortar sample;
preparing a silicon dioxide standard solution according to a method of 6.1.72 in GB/T176-2017, and drawing a working curve;
weighing 1.5 +/-0.1 g of mortar sample, weighing 0.2 +/-0.05 g of cement sample, putting the weighed mortar sample into a beaker, pouring 100mL of hydrochloric acid solution with the temperature of 3-5 ℃ and the volume fraction of 25%, stirring for 20min at the temperature of 3-5 ℃, filtering by using medium-speed filter paper X, washing at least twice by using 50 ℃ hot water, then transferring all the medium-speed filter paper X and filter residues into a plastic beaker, pouring 75mL of NaOH solution with the temperature of 50 ℃ and the concentration of 10g/L, putting into a 50 ℃ water bath for 15min, filtering by using medium-speed filter paper Y, washing by using 50 ℃ hot water until the filtrate is neutral, finally collecting all the filtrates, and carrying out volume metering to 500mL to obtain a solution B;
step five, soluble SiO in the mortar2Content (wt.)
Putting the solution B into a volumetric flask, adding water to dilute the solution B to 40mL, sequentially adding 5.0mL of hydrochloric acid solution with the volume fraction of 9%, 8.0mL of absolute ethyl alcohol and 6.0mL of ammonium molybdate solution with the concentration of 50g/L, uniformly mixing, standing for 30min, sequentially adding 20mL of hydrochloric acid solution with the volume fraction of 50% and 5.0mL of ascorbic acid solution with the concentration of 5g/L, finally diluting to 100mL by using distilled water, shaking up, standing for 60min, and measuring the absorbance at 660mm by using a spectrophotometer;
soluble SiO in mortar or cement samples2The content is C, and the unit is%;
wherein c is soluble SiO in the solution in the volume bottle2The content is found in a working curve according to the absorbance, and the unit is mu g/mL; m is the mass of the mortar sample or the cement sample, and the unit is g; v is the volume of the solution B to be detected, and the unit is mL;
step six, the content of cement and mineral powder in the mortar
C3The content of cement and mineral powder in the mortar sample is shown in unit; c1Is soluble SiO in mortar sample2Content, in%; c2Is soluble SiO in cement sample2Content, in%;
seventhly, the content of cement and mineral powder in the hardened concrete
The content of cement and mineral powder in the core sample is Hi，
2. The method for determining the contents of cement and mineral powder in hardened concrete according to claim 1, wherein the method comprises the following steps: in the first step, the diameter of the core sample obtained by adopting a core drilling method is more than or equal to 3 times of the particle size of the coarse aggregate.
3. The method for determining the contents of cement and mineral powder in hardened concrete according to claim 1, wherein the method comprises the following steps: in the first step, each core sample obtained has a mass greater than or equal to 2 kg; the cores are taken at least 5 different parts of the concrete of the same batch, and the total mass of the core sample is not less than 10 kg.
4. The method for determining the contents of cement and mineral powder in hardened concrete according to claim 1, wherein the method comprises the following steps: in the fourth step, the absolute ethyl alcohol is adopted for soaking treatment, the soaking time is 24 hours, and the absolute ethyl alcohol is replaced every 12 hours.
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| CN112748079A (en) * | 2020-12-23 | 2021-05-04 | 中山艾尚智同信息科技有限公司 | Method for measuring mud content of natural sand for building |
| CN116754754A (en) * | 2023-08-08 | 2023-09-15 | 河北路诚检测技术有限公司 | Detection equipment for detecting raw materials of highway bridge |
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| CN112748079A (en) * | 2020-12-23 | 2021-05-04 | 中山艾尚智同信息科技有限公司 | Method for measuring mud content of natural sand for building |
| CN116754754A (en) * | 2023-08-08 | 2023-09-15 | 河北路诚检测技术有限公司 | Detection equipment for detecting raw materials of highway bridge |
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Application publication date: 20201009 |