A method for testing the adsorption amount of a water-reducing agent for cementitious materials and application thereof

Abstract

The present application relates to the field of water-reducing agent adsorption capacity test method, in particular to a cementitious material water-reducing agent adsorption capacity test method and application thereof, and provides a cementitious material water-reducing agent adsorption capacity test method, which can accurately and quickly evaluate the adsorption capacity of cementitious material to water-reducing agent, and is convenient for subsequent optimization and improvement of concrete formula.

Description

TECHNICAL FIELD

[0001] The application relates to the field of water-reducing agent adsorption amount test methods, in particular to a cementitious material water-reducing agent adsorption amount test method and application thereof. BACKGROUND

[0002] At present, various super high-rise and large-span building projects are increasing, and building projects are developing towards large-scale. Water-reducing agents are necessary water-reducing agents for high-performance concrete and affect the overall stability of the concrete. However, due to the relatively unstable quality of coarse and fine aggregates used in the preparation of concrete in China, especially the high and unstable powder content of the crushed stone and machine-made sand, and the use of cementitious materials and auxiliary cementitious materials, the adsorption of water-reducing agents will easily cause the water-reducing rate of water-reducing agents to decrease, affect the realization of the water-reducing function of water-reducing agents, and further affect the comprehensive performance of the concrete. However, at present, the adsorption amount of water-reducing agents is generally tested by the methylene blue adsorption test method in the national standard, which characterizes the adsorption amount of cementitious materials on water-reducing agents by testing the adsorption amount of methylene blue on water-reducing agents. The effect corresponding to the actual construction result is not significant, that is, the accuracy of the test result of the test method is insufficient. SUMMARY

[0003] Therefore, the present application provides a cementitious material water-reducing agent adsorption amount test method, which can accurately and quickly evaluate the adsorption amount of cementitious materials on water-reducing agents, and is convenient for subsequent optimization and improvement of concrete formulations.

[0004] In one aspect, the application provides a cementitious material water-reducing agent adsorption amount test method, which at least comprises the following steps:

[0005] (1) preparing cement mortar and performing a cement mortar spreadability test;

[0006] (2) preparing a to-be-tested powder mortar and performing a to-be-tested powder mortar spreadability test, wherein the to-be-tested powder in the to-be-tested powder mortar is cementitious material, auxiliary cementitious material and machine-made sand with a powder content of more than 5%;

[0007] (3) comparing the water-reducing agent content measured by the cement and the water-reducing agent content measured by the to-be-tested powder to obtain the adsorption amount of the to-be-tested powder on the water-reducing agent.

[0008] As a preferred technical solution, the preparation raw materials of the cement mortar at least include cement, ISO standard sand, water and water-reducing agent.

[0009] Preferably, the mixing ratio of the cement mortar is shown in Table 1.

[0010] Table 1,

[0011]

[0012] As a preferred technical solution, the reference water reducing agent is a liquid non-slump-retaining water reducing polycarboxylate mother liquor without adding a retarder, and is diluted with water to a solid content of 10%.

[0013] As a preferred technical solution, the to-be-tested powder mortar at least comprises cement, to-be-tested powder, ISO standard sand, water, and water reducing agent.

[0014] Preferably, the mass ratio of the cement to the to-be-tested powder is 3:7-7:3; preferably, the mass ratio of the cement to the to-be-tested powder is 7:3.

[0015] As a preferred technical solution, the cement is cement meeting the provisions of GB 175.

[0016] As a preferred technical solution, the ISO standard sand is a graded standard sand meeting the provisions of GB / T 17671.

[0017] The inventors found in the process of experimental exploration that, by controlling the mass ratio of the cement to the to-be-tested powder to be 7:3 to prepare the to-be-tested powder mortar and performing the spreadability test, the uniformity of the result of the adsorption amount of the to-be-tested powder to the water reducing agent is high, and the repeatability is good.

[0018] As a preferred technical solution, the mix proportion of the to-be-tested powder mortar is shown in Table 2.

[0019] Table 2,

[0020]

[0021] As a preferred technical solution, the spreadability test comprises initial spreadability test and spreadability test over time.

[0022] Preferably, the initial spreadability is defined as the spreadability immediately after the completion of the stirring of the mortar; and the spreadability over time is defined as the spreadability after the mortar is stored for a certain time under the specified conditions and then stirred again according to the requirements.

[0023] As a preferred technical solution, the initial spreadability test method comprises the following steps:

[0024] S1, preparing the surface of the stirring instrument before the test;

[0025] S2, stirring and mixing the water reducing agent with water;

[0026] S3, then adding the cement and the to-be-tested powder and the ISO standard sand into the stirring instrument to obtain the mortar;

[0027] S4, quickly inject the mortar into the mold, scrape it flat with a ruler, and lift the mold vertically, allowing the mortar to flow freely on the glass plate until it stops flowing, measure the diameters of the two directions perpendicular to each other of the flowing part with a steel ruler, and take the average value as the initial expansion degree.

[0028] As a preferred technical solution, the initial expansion degree test method specifically comprises the following steps:

[0029] S1, before starting the test, wipe the stirring blade and stirring pot with a wet cloth to make the surface wet but not with water stains;

[0030] S2, weigh the water reducing agent (accurate to 0.02g) in a container with a volume not greater than 100mL, and place the water reducing agent in the stirring pot; weigh 240g of water (accurate to 0.5g) in a 300mL plastic beaker, rinse the container containing the water reducing agent with water 3 times, and combine the washing water and the remaining water in the stirring pot with the water reducing agent; shake the stirring pot gently to mix the water reducing agent with the water;

[0031] S3, weigh the cement and the powder to be tested into the stirring pot. Place the stirring pot on the fixed frame and raise it to the fixed position; start the automatic stirring program of the mortar mixer; stir at low speed for 60s, and add the ISO standard sand uniformly during the last 30s; stir at high speed for another 30s, stop for 90s, and scrape the mortar on the stirring blade and pot wall into the middle with a ruler during the first 15s, and continue to stir at high speed for 60s; record the starting time of the mixer;

[0032] S4, while stirring the mortar, place the glass plate in a horizontal position, wipe the glass plate, truncated cone round mold, and place them in the center of the glass plate with a wet cloth, and cover them with a wet cloth for standby; after the mixer stops, remove the stirring pot, quickly wipe the glass plate and truncated cone round mold again with a wet cloth, quickly inject the stirred mortar into the truncated cone round mold, scrape it flat with a ruler, lift the truncated cone round mold vertically, allow the mortar to flow freely on the glass plate until it stops flowing (about 30s after the mold is lifted), measure the diameters of the two directions perpendicular to each other of the flowing part with a steel ruler, and take the average value as the initial expansion degree.

[0033] As a preferred technical solution, the initial expansion degree test method specifically comprises the following steps:

[0034] The slurry after initial expansion degree test is scraped into the stirring pot with a ruler, and after being placed with a wet cloth cover, the stirring pot is placed on the fixed frame of the mortar stirrer, and is raised to the fixed position; the stirrer is started, and the mortar is stirred slowly or manually for 30s, then the stirred mortar is quickly injected into the truncated cone round mold, and is scraped flat with a ruler, and the truncated cone round mold is lifted in the vertical direction, and the mortar is allowed to flow freely on the glass plate until it stops flowing (about 30s after the mold is lifted), and the diameters of two directions perpendicular to each other of the flowing part are measured with a steel ruler, and the average value is taken as the expansion degree over time.

[0035] As a preferred technical solution, the standing time is 30-60 min.

[0036] As a preferred technical solution, the repeatability of the initial expansion degree and the expansion degree over time is 5 mm, and the reproducibility is 8 mm.

[0037] As a preferred technical solution, the water is tap water or drinking water.

[0038] As a preferred technical solution, all test materials in the test method are pre-constant temperature to 20℃±2℃ in the laboratory.

[0039] As a preferred technical solution, the test conditions in the test method are that the temperature is kept at 20℃±2℃, and the relative humidity is not less than 50%.

[0040] In the application, by strictly controlling the temperature conditions, the relative humidity conditions and the addition amount of each raw material of the mortar, the truncated cone round mold and the glass plate are kept surface wet and without water stains, the test error is reduced, and the accuracy of the test results is ensured.

[0041] As a preferred technical solution, the cement mortar expansion degree test result is that the dosage of the water reducing agent when the initial expansion degree of the cement mortar is 220mm±20mm.

[0042] As a preferred technical solution, the expansion degree result of the to-be-tested powder mortar is that the dosage of the water reducing agent when the initial expansion degree of the to-be-tested powder mortar is 220mm±20mm.

[0043] As a preferred technical solution, the adsorption amount of the to-be-tested powder to the water reducing agent is calculated by the formula (the increment of the to-be-tested powder to the water reducing agent = the measured dosage of the water reducing agent of the cement - the measured dosage of the water reducing agent of the cement).

[0044] Another aspect of the application provides an application of the test method for the adsorption amount of the water reducing agent of the cementitious material, which is applied to the determination of the adsorption amount of the water reducing agent of the cementitious material, the auxiliary cementitious material and the machine-made sand with a powder content of more than 5%.

[0045] Beneficial effects:

[0046] (1) The present application provides a cementitious material water-reducing agent adsorption amount test method, which can accurately and quickly evaluate the adsorption amount of water-reducing agent by cementitious material, and facilitate the optimization and improvement of subsequent concrete formulation.

[0047] (2) The present application controls the mass ratio of the cement and the to-be-tested powder to be 7:3 to prepare the to-be-tested powder mortar and perform the spreadability test, and the uniformity of the adsorption amount of water-reducing agent by the to-be-tested powder obtained by the test at the ratio is high, and the repeatability is good.

[0048] (3) In the present application, the temperature condition, the relative humidity condition and the addition amount of each raw material of the mortar are strictly controlled, the truncated cone glass plate and the glass plate are kept wet and free of water stains, the test error is reduced, and the accuracy of the test result is ensured. DETAILED DESCRIPTION

[0049] Example 1

[0050] The cementitious material water-reducing agent adsorption amount test method provided by the embodiment 1 of the present application comprises the following steps:

[0051] (1) preparing the cement mortar and performing the cement mortar spreadability test;

[0052] (2) preparing the to-be-tested powder mortar and performing the to-be-tested powder mortar spreadability test, wherein the to-be-tested powder in the to-be-tested powder mortar is cementitious material, auxiliary cementitious material and machine-made sand with a powder content of more than 5%;

[0053] (3) comparing the water-reducing agent content measured by the cement and the water-reducing agent content measured by the to-be-tested powder to obtain the adsorption amount of water-reducing agent by the to-be-tested powder.

[0054] The mixing ratio of the cement mortar is shown in Table 3.

[0055] Table 3,

[0056]

[0057] The mixing ratio of the to-be-tested powder mortar is shown in Table 4.

[0058] Table 4,

[0059]

[0060]

[0061] The cement is a cement meeting the requirements of GB 175, and the cement is from Guangdong Taiku (Yingde) Cement Co., Ltd.

[0062] The ISO standard sand is a standard sand complying with the provisions of GB / T 17671, and the sand is Xiamen ISO standard sand.

[0063] The spread test includes initial spread test and time-dependent spread test.

[0064] The initial spread is defined as the spread immediately after the completion of mortar mixing; and the time-dependent spread is defined as the spread after the mortar is stored for a certain time under specified conditions and then is mixed again according to the requirements.

[0065] The cement mortar initial spread test method specifically includes the following steps:

[0066] S1, before starting the test, the stirring blade and the stirring pot are wiped with a wet cloth to make the surface wet but not with water stains;

[0067] S2, a container with a volume of 100 mL is used to weigh the water reducing agent (accurate to 0.02 g) according to Table 3, and the water reducing agent is placed in the stirring pot; 240 g of water (accurate to 0.5 g) is weighed in a 300 mL plastic beaker according to Table 3, the container containing the water reducing agent is washed with water for 3 times, and the washing water and the remaining water are combined in the water reducing agent in the stirring pot; the stirring pot is shaken gently to mix the water reducing agent and the water;

[0068] S3, 600 g of cement (accurate to 0.5 g) is weighed according to the provisions of Table 3 and placed in the stirring pot; the stirring pot is placed on the fixed frame and raised to the fixed position; the automatic stirring program of the mortar mixer is started; the stirring is carried out at low speed for 60 s, and the ISO standard sand is uniformly added during the last 30 s; the stirring is carried out at high speed for another 30 s, and stopped for 90 s; during the first 15 s, the mortar on the stirring blade and the pot wall is scraped into the middle with a spatula, and the stirring is continued at high speed for 60 s; the starting time of the mortar mixer is recorded;

[0069] S4, while the mortar is being mixed, the glass plate is placed in a horizontal position, the glass plate, the truncated cone round mold are wiped with a wet cloth, and they are placed in the center of the glass plate, and a wet cloth is covered for standby; after the mortar mixer is stopped, the stirring pot is taken out, the glass plate and the truncated cone round mold are uniformly wiped again with a wet cloth, the mixed mortar is quickly poured into the truncated cone round mold, the mortar is scraped flat with a spatula, the truncated cone round mold is lifted in the vertical direction, and the mortar is allowed to flow freely on the glass plate until the flow stops (about 30 s after the mold is lifted), the diameters of two directions perpendicular to each other of the flowing part are measured with a steel ruler, and the average value is taken as the initial spread of the cement mortar.

[0070] The cement mortar time-dependent spread test method specifically includes the following steps:

[0071] The cement mortar initial expansion degree of the tested cement mortar is scraped into the mixing pot with a ruler, and after being placed with a wet cloth cover, the mixing pot is placed on the mortar mixer fixed frame, and is raised to the fixed position; the mixer is started, and after being stirred at a slow speed for 30s, the stirred mortar is quickly injected into the truncated cone round mold, and is scraped flat with a ruler. The truncated cone round mold is lifted in the vertical direction, and the mortar is allowed to flow freely on the glass plate until it stops flowing (about 30s after the mold is lifted). The diameters of the two directions perpendicular to each other of the flowing part are measured with a steel ruler, and the average value is taken as the cement mortar expansion degree over time.

[0072] The initial expansion degree test method of the tested powder mortar specifically includes the following steps:

[0073] S1, before starting the test, the stirring blade and the mixing pot are wiped with a wet cloth to make the surface wet but not with water stains;

[0074] S2, in a container with a volume of 100ml, the water reducing agent is weighed according to table 4 (accurate to 0.02g), and the water reducing agent is placed in the mixing pot. In a 300ml plastic beaker, 240g of water is weighed according to table 4 (accurate to 0.5g). The container containing the water reducing agent is washed with water three times, and the washing water and the remaining water are combined in the water reducing agent in the mixing pot. Lightly shake the mixing pot to mix the water reducing agent and water;

[0075] S3, 420g of cement and 180g of the tested powder are weighed according to table 4 (accurate to 0.5g) and placed in the mixing pot. The mixing pot is placed on the fixed frame and raised to the fixed position. The mortar mixer is started and the automatic stirring program is started. Stir at a low speed for 60s, and during the last 30s, add the ISO standard sand uniformly. Stir at a high speed for another 30s, stop for 90s, and in the first 15s, use a ruler to scrape the mortar on the stirring blade and the pot wall into the middle, and continue to stir at a high speed for 60s. Record the start time of the mixer;

[0076] S4, while stirring the mortar, place the glass plate in a horizontal position, wipe the glass plate and the truncated cone round mold with a wet cloth, and place them in the center of the glass plate, cover them with a wet cloth for standby. After the mixer stops, remove the mixing pot, and quickly wipe the glass plate and the truncated cone round mold again with a wet cloth. The stirred mortar is quickly injected into the truncated cone round mold, and is scraped flat with a ruler. The truncated cone round mold is lifted in the vertical direction, and the mortar is allowed to flow freely on the glass plate until it stops flowing (about 30s after the mold is lifted). The diameters of the two directions perpendicular to each other of the flowing part are measured with a steel ruler, and the average value is taken as the cement mortar initial expansion degree.

[0077] The initial expansion degree test method of the tested powder mortar specifically includes the following steps:

[0078] The mortar with the initial expansion degree of the tested powder mortar to be measured is scraped into the stirring pot with a ruler, and after being placed in a wet cloth cover, the stirring pot is placed on the fixed frame of the mortar mixer, and is lifted to the fixed position; the mixer is started, and the mortar is stirred slowly for 30s, and then the stirred mortar is quickly injected into the truncated cone round mold, and is scraped flat with a ruler, and the truncated cone round mold is lifted in the vertical direction, and the mortar is allowed to flow freely on the glass plate until it stops flowing (about 30s after the mold is lifted), and the diameters of two directions perpendicular to each other of the flowing part are measured with a steel ruler, and the average value is taken as the expansion degree of the tested powder mortar over time.

[0079] The standing time is 60 min.

[0080] The water is drinking water.

[0081] The tested powder is Guangxi Fangchenggang S95 mineral powder.

[0082] The water reducing agent is all liquid non-cushioning water reducing type polycarboxylic acid water reducing agent mother liquor without adding a retarder (the non-cushioning water reducing type polycarboxylic acid water reducing agent mother liquor is from Guangdong Kexijie New Material Group Co., Ltd.), and is diluted with water to a solid content of 10%.

[0083] All test materials in the test method are pre-constant temperatureed to 20℃±2℃ in the laboratory.

[0084] The test conditions in the test method are that the temperature is kept at 20℃±2℃, and the relative humidity is 50%.

[0085] The cement mortar expansion degree test result is that the dosage of the water reducing agent when the initial expansion degree of the cement mortar is 220 mm.

[0086] The tested powder mortar expansion degree result is that the dosage of the water reducing agent when the initial expansion degree of the tested powder mortar is 220 mm.

[0087] The adsorption amount of the tested powder to the water reducing agent is calculated by the formula (the increment of the tested powder to the water reducing agent = the measured dosage of the water reducing agent of the tested powder - the measured dosage of the water reducing agent of the cement).

[0088] The embodiment 1 of the application further provides an application of the cementitious material water reducing agent adsorption amount test method, and is applied to the determination of the adsorption amount of the water reducing agent of the cementitious material, the auxiliary cementitious material and the machine-made sand with a powder content of more than 5%.

[0089] Embodiment 2

[0090] The embodiment 2 of the application provides a cementitious material water reducing agent adsorption amount test method and application thereof, and the specific implementation manner is the same as that of the embodiment 1, and the difference is shown in Table 5.

[0091] Embodiment 3

[0092] Embodiment 3 of the present application provides a gelling material water-reducing agent adsorption amount test method and application thereof, the specific implementation manner is same as embodiment 1, and the difference is referred to table 5.

[0093] Performance test method

[0094] (1) the water-reducing agent mixing amount result measured by cement is referred to table 5.

[0095] (2) the water-reducing agent mixing amount result measured by the powder to be tested is referred to table 5.

[0096] (3) the adsorption amount of water-reducing agent by the powder to be tested is referred to table 5.

[0097] Table 5

[0098]

Claims

1. A method for testing the adsorption amount of a water-reducing agent for a cementitious material, characterized by, At least comprising the following steps: (1) preparing cement mortar and performing cement mortar spreadability test; (2) preparing powder mortar to be tested and performing powder mortar to be tested spreadability test, wherein the powder to be tested in the powder mortar to be tested is cementitious material, auxiliary cementitious material and machine-made sand with powder content exceeding 5%; (3) comparing the water reducing agent dosage measured in the cement mortar and the water reducing agent dosage measured in the powder mortar to be tested to obtain the adsorption amount of the powder to be tested on the water reducing agent; (4) using water reducing agent increment to represent the adsorption amount of the cementitious material on the water reducing agent; the raw materials for preparing the cement mortar at least include cement, ISO standard sand, water and water reducing agent; the powder mortar to be tested at least includes cement, powder to be tested, ISO standard sand, water and water reducing agent, and the mass ratio of the cement to the powder to be tested is 7:3; the cement is cement meeting the provisions of GB 175; the ISO standard sand is standard sand of each level meeting the provisions of GB / T 17671; the spreadability test includes initial spreadability test and spreadability test over time; The initial spreadability test method comprises the following steps: S1, preparing the surface of the stirring instrument before the test; S2, stirring and mixing the water reducing agent with water respectively and adding them into the stirring instrument; S3, then adding cement or cement and powder to be tested, ISO standard sand into the stirring instrument to obtain mortar; S4, quickly injecting the mortar into the test mold, leveling it with a ruler, lifting the test mold in the vertical direction, allowing the mortar to flow freely on the glass plate until it stops flowing, measuring the diameters of the two directions perpendicular to each other of the flowing part with a steel ruler, and taking the average value as the initial spreadability; The spreadability test over time method specifically comprises the following steps: After the mortar with the initial spreadability is tested, scrape it into the stirring pot with a ruler, cover it with a wet cloth, and after standing, slowly stir it with a stirrer or stir it manually for 30s, then quickly inject the stirred mortar into a truncated cone round mold, level it with a ruler, lift the truncated cone round mold in the vertical direction, allow the mortar to flow freely on the glass plate until it stops flowing, measure the diameters of the two directions perpendicular to each other of the flowing part with a steel ruler, and take the average value as the spreadability over time.

2. Use of the method for testing the adsorptive capacity of a water-reducing agent for a cementitious material according to claim 1, characterized in that, It is applied to the determination of the adsorption amount of cementitious material, auxiliary cementitious material and machine-made sand with powder content exceeding 5% on water reducing agent.

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