A device and method for measuring competitive adsorption of multi-component gelling materials

Abstract

The present invention discloses a measuring device and a measuring method for competitive adsorption of multi-component cementitious materials. The measuring device includes several individual components of the measuring device and a test container. The test container contains a concrete simulated pore solution containing a polycarboxylate water-reducing agent, and the individual components of the measuring device are placed in the test container respectively. Each individual component of the measuring device includes a dialysis bag, which is used to allow water and polycarboxylate water-reducing agent to pass through during the adsorption test and to isolate the various components of the cementitious material from the solution in the beaker. The single component of the cementitious material is placed in the dialysis bag. Through this device, each component can fully adsorb PCE molecules and then be easily separated, so as to measure the adsorption amount of PCE molecules on each component separately. During the entire adsorption process, each sample will not interfere with each other, ensuring the consistency of the solution concentration. The competitive adsorption situation is judged by analyzing the adsorption amount of PCE molecules on each component.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and in particular relates to a measuring device and a measuring method for competitive adsorption of multi-component gelling materials. Background Art

[0002] Polycarboxylate superplasticizer (PCE) is one of the most critical admixtures in cement concrete. Composed of copolymers of unsaturated monomers containing carboxyl groups and other monomers, PCE improves concrete's water-reducing and slump-retaining properties, and boasts plasticity, low shrinkage, and environmental friendliness. It is generally believed that comb-like polycarboxylate superplasticizers primarily adsorb onto the surfaces of cement particles or hydrated cement particles through charged groups in their main chains, generating electrostatic repulsion. Simultaneously, the long side chains within the molecular structure create a steric hindrance effect, breaking up the cohesive structures between adjacent cement particles and releasing the free water trapped within them, thereby achieving viscosity and water reduction. Some scholars believe that the mechanism by which polycarboxylate superplasticizers effectively control concrete slump loss is primarily due to the continuous hydrolysis of the ester or anhydride functional groups in the superplasticizer molecules in the alkaline environment of the cement paste, generating strongly anionic functional groups. This imparts a negative charge to the surface of the cement particles or hydrated cement particles, leading to the continuous disintegration of cement particle flocs through electrostatic repulsion and excellent dispersion properties. Most researchers believe that a higher degree of polymerization (DOP) of the polyoxyethylene side chains in polycarboxylate superplasticizers (PCEs) facilitates the dispersion of cement floccules. This is because the long side chains enhance the steric repulsion between cement particles or hydrated cement particles. PCE performance is directly related to concrete strength, durability, and other key performance indicators. The adsorption characteristics of PCEs on cementitious materials are an important indicator for evaluating the effectiveness of their molecular structure.

[0003] Currently, cement-based binders mostly use multi-component, low-carbon formulations. The adsorption of PCE on these different components has a decisive influence on their ultimate dispersion. Therefore, in-depth research on the adsorption behavior of PCE molecules on the various components of binders is extremely important.

[0004] Early studies of the adsorption properties of water-reducing agents used ultraviolet spectrophotometry. This method typically uses a high water-cement ratio. After the mixture of cement and water-reducing agent is stirred and allowed to stand for a period of time, the supernatant is aspirated and centrifuged. The supernatant is then collected and the supernatant concentration is determined using a UV spectrophotometer. The adsorption capacity is then calculated based on the concentration difference compared to a blank sample (no cement added). However, this method has drawbacks: First, the water-cement ratio is too high, far exceeding the actual water-cement ratio of concrete systems. This affects the properties of cement particles during initial hydration and, in turn, their adsorption capacity for the water-reducing agent. Second, cement particles smaller than 1 μm, which are difficult to separate and precipitate even under high-speed centrifugation, often affect the test results, resulting in significant errors. In their paper "Effects of the Molecular Structure of Polycarboxylate Water-Reducing Agents on Their Adsorption Properties on Cementitious Materials," Li An et al. used an Elementar Liqui TOC instrument to measure total organic carbon (TOC) content, using a hydrochloric acid solution as the eluent. The residual content of PCE in the cement / fly ash / mineral powder slurry solution at the initial time (5 min) and at 20, 40, 60, 90, and 120 min was calculated based on the TOC content. The adsorption amount of PCE on the surface of the cementitious material at different times was then obtained by calculating the difference in TOC content before and after adsorption.

[0005] However, due to the large differences in the adsorption properties of different mineral admixtures and cements on polycarboxylate superplasticizers and the existence of competitive adsorption, existing testing equipment is unable to accurately simulate and measure the competitive adsorption phenomenon of PCE in multi-component cementitious materials. Summary of the Invention

[0006] Given that existing testing devices are unable to accurately simulate and measure the competitive adsorption phenomenon of PCE in multi-component gelling materials, in response to the problems existing in the background technology, the present invention provides a measuring device and method for competitive adsorption of multi-component gelling materials, which can enable each component to fully adsorb PCE molecules and then easily separate them, thereby separately measuring the adsorption amount of PCE molecules on each component.

[0007] In order to achieve the above technical objectives, the technical solutions implemented by the present invention are:

[0008] In one aspect, the present invention provides a device for measuring competitive adsorption of multi-component cementitious materials, comprising a plurality of individual components of the device and a test container, wherein the test container contains a concrete simulated pore solution containing a polycarboxylate water-reducing agent, and the individual components of the device are placed in the test container respectively;

[0009] Each individual component of the measuring device includes a dialysis bag, which allows water and polycarboxylate water-reducing agent to pass through during the adsorption test and prevents the polycarboxylate water-reducing agent solid from being dispersed into the solution in the test container;

[0010] A single component of gelling material is placed in the dialysis bag.

[0011] Preferably, each individual component of the assay device further comprises a clamping member for sealing the dialysis bag. In an embodiment of the present invention, the clamping member is a plastic clamp.

[0012] In an embodiment of the present invention, the test container is a beaker.

[0013] Furthermore, the measuring device further comprises a magnetic stirrer, the test container is placed on a magnetic stirrer tray, and a rotor is placed in the test container to ensure consistency of solution concentration.

[0014] Another aspect of the present invention provides a method for determining competitive adsorption of a multi-component gelling material, comprising the following steps:

[0015] Step 1: Pour the SCPS solution (concrete simulated pore solution) into the test container, weigh an appropriate amount of polycarboxylate superplasticizer (PCE) and add it to the SCPS solution. Set the magnetic stirrer speed between 200-800 rpm and stir until fully dissolved. Sampling is performed to measure the total organic carbon (TOC) concentration in the solution at this time, which is recorded as C0.

[0016] Step 2: Place the gelling material in the dialysis bag of the measuring device and seal it. Then, place the individual components of the assembled measuring devices into the solution simultaneously. The components of the gelling material fully adsorb PCE under the action of the rotor stirring. After adsorption for 2-10 minutes, remove the material from the beaker. At this time, sample the solution in the beaker, acidify it, and test the total organic carbon content, which is recorded as C1.

[0017] Step 3: After fully adsorbing PCE, each component is taken out from the dialysis bag, diluted with deionized water by a certain multiple (K1), and centrifuged. At this time, the PCE attached to the surface of the gelling material but not yet adsorbed is centrifuged to the supernatant. The supernatant is taken for acidification and the total organic carbon content is measured, which is recorded as C2. At the same time, in order to eliminate the influence of PCE attached to the dialysis membrane, the dialysis membrane is placed in a centrifuge tube, diluted with deionized water by a certain multiple (K2), and centrifuged. The supernatant is taken for acidification and the total organic carbon content is measured, which is recorded as C3.

[0018] In step 3, the centrifugal operation speed is 6000-10000 rpm, and the centrifugation time is 6-12 min.

[0019] Preferably, in step 1, the concrete simulation pore solution is an aqueous solution, wherein the ion concentration range is Ca 2+ 0.2-0.6g / L,Na + 1.5-3g / L,K + 5-10g / L,SO4 2- 6-12g / L,OH - 2-2.5g / L.

[0020] Preferably, in step 1, the total organic carbon concentration C0 in the concrete simulation pore solution is in the range of 24-120 mg / L.

[0021] Preferably, in step 2, the ratio of the total amount of each group of cementitious materials added in the measuring device to the polycarboxylate superplasticizer in step 1 is: 1g of cementitious materials corresponds to 4-15mg of polycarboxylate superplasticizer (PCE); and the amount of cementitious materials added in each group is equal.

[0022] The competitive adsorption results were calculated using the following formula:

[0023]

[0024] Wherein, C is the final calculated concentration of PCE adsorbed on the surface of the cementitious material, mg / L;

[0025] C0 is the initial carbon concentration of the solution, mg / L;

[0026] C1 is the carbon concentration in the remaining solution after adsorption occurs, mg / L;

[0027] C2 is the concentration of free carbon that has not been adsorbed on the surface of the cementitious material after the cementitious material is diluted, and K1 is the dilution multiple when the cementitious material is diluted;

[0028] C3 is the carbon concentration in the supernatant after the dialysis membrane is diluted with deionized water and centrifuged, and K2 is the corresponding dilution multiple.

[0029] In some embodiments, the components of the multi-component cementitious material include cement clinker, calcined clay, limestone powder, granulated blast furnace slag powder, steel slag powder, fly ash, rice husk ash, silica fume, phosphorus slag powder, zeolite powder and composite mineral admixtures.

[0030] Furthermore, the multi-component cementitious material comprises cement clinker, calcined clay and limestone powder.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention provides a device and method for measuring competitive adsorption of multi-component gelling materials, which can effectively solve the problem of detecting the competitive adsorption of each component in a PCE solution when multiple components coexist. Through this device, each component can fully adsorb PCE molecules and then easily separate them, so that the amount of PCE molecules adsorbed on each component can be measured separately. During the entire adsorption process, the three samples will not interfere with each other, ensuring the consistency of solution concentration. The competitive adsorption situation is determined by analyzing the amount of PCE molecules adsorbed on each component.

[0033] (2) In addition, the experimental equipment used in the present invention is relatively common, has a simple structure, is easy to assemble, and has a highly flexible condition control capability. The device is also reusable, further improving its practicality and cost-effectiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0035] Figure 1 A structural diagram of a single component of a multi-component gelling material competitive adsorption assay device provided in Example 1;

[0036] Figure 2 This is a schematic diagram of the overall structure of a measurement device for competitive adsorption of multi-component gelling materials provided in Example 1.

[0037] Among them, 1-dialysis bag, 2-gel material single component, 3-plastic clamp, 4-beaker, 5-PCE solution, 6-rotor, 7-magnetic stirrer. DETAILED DESCRIPTION

[0038] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0039] Example 1, a device for measuring competitive adsorption of multi-component gelling materials

[0040] like Figure 1 and Figure 2 As shown, 1 is a dialysis bag, which is used to allow water and polycarboxylate superplasticizer (PCE) to pass through during the adsorption test and to isolate the various components of the gelling material from the solution in the beaker; 2 is a single component of the gelling material involved in the adsorption test; 3 is a plastic clip, which clamps the two sides of the dialysis bag to prevent the solid from dispersing into the beaker solution; 4 is a beaker, used to hold the solution; 5 is the PCE solution; 6 is a rotor, which ensures the consistency of the solution concentration; and 7 is a magnetic stirrer.

[0041] Figure 1Shown is a single component of a multi-component gelling material competitive adsorption assay. A dialysis bag 1, fitted with a plastic clip 3, holds the single gelling material component involved in the adsorption test. Dialysis bag 1, also known as a dialysis membrane or semipermeable membrane, is a specialized membrane material that allows small solute molecules to pass but blocks large solute molecules. Dialysis bags are widely used in biochemistry, medicine, biotechnology, and other fields to separate and purify molecules of varying sizes or properties. The molecular weight of PCE is typically less than 6W, so a dialysis bag with a molecular weight cutoff of less than 10W was selected.

[0042] like Figure 2 As shown, a single component of the assembled measuring device is placed in a beaker 4. The single component is not fixed in the beaker and can rotate with the solution. A PCE solution 5 is pre-poured into the beaker 4. The PCE solution 5 is an SCPS solution containing PCE. A magnetic rotor 6 is placed at the bottom of the beaker 4, and the beaker 4 is placed on a tray of a magnetic stirrer 7.

[0043] As a typical embodiment, three groups of individual components of the measuring device are placed in the beaker 4, and a single component of a gelling material with a different composition is pre-added into each component.

[0044] Example 2, a method for determining competitive adsorption of multi-component gelling materials

[0045] Test method:

[0046] Step 1: Pour the SCPS solution (concrete simulated pore solution (SCPS)) into a beaker 4, weigh an appropriate amount of polycarboxylate superplasticizer (PCE) and add it to the SCPS solution. Set the magnetic stirrer speed to between 200-800 rpm and stir until fully dissolved. Sampling is performed to measure the total organic carbon (TOC) concentration in the solution at this time, which is recorded as C0.

[0047] Step 2: Place the individual components of the prepared multiple measuring devices into the solution simultaneously. The various components of the gelling material fully adsorb PCE under the action of the rotor stirring. After 4 minutes of adsorption, the material is removed from the beaker. At this time, a sample of the solution in the beaker is taken, and the total organic carbon content is measured after acidification, which is recorded as C1.

[0048] In this step, the adsorption time is within the range of 2-10 minutes. If the adsorption time is too short, incomplete adsorption will result. If the adsorption time is too long, the cement clinker will be hydrated, resulting in the problem that the PCE adsorption target is converted into hydrated tricalcium silicate, ettringite, calcium hydroxide, etc., which are hydrated products.

[0049] Acidification treatment uses 1 mol / L hydrochloric acid solution, and 10 drops of 1 mol / L hydrochloric acid solution are added to every 20 g of sample.

[0050] Step 3: After fully adsorbing PCE, each component is taken out from the dialysis bag, diluted with deionized water by a certain multiple (K1), and centrifuged at 8500 rpm for 10 minutes. At this time, the PCE attached to the surface of the gelling material but not yet adsorbed is centrifuged to the supernatant. The supernatant is taken for acidification and the total organic carbon content is measured, which is recorded as C2. At the same time, in order to eliminate the influence of PCE attached to the dialysis membrane, the dialysis membrane is placed in a centrifuge tube, diluted with deionized water by a certain multiple (K2), and centrifuged at 8500 rpm for 10 minutes. The supernatant is taken for acidification and the total organic carbon content is measured, which is recorded as C3.

[0051] As a feasible implementation method, during the centrifugal operation, the rotation speed can be 6000-10000 rpm and the centrifugation time can be 6-12 minutes.

[0052] The competitive adsorption results were calculated using the following formula:

[0053]

[0054] Wherein, C is the final calculated concentration of PCE adsorbed on the surface of the cementitious material, mg / L;

[0055] C0 is the initial carbon concentration of the solution, mg / L;

[0056] C1 is the carbon concentration in the remaining solution after adsorption occurs, mg / L;

[0057] C2 is the concentration of free carbon that has not been adsorbed on the surface of the cementitious material after the cementitious material is diluted, and K1 is the dilution multiple when the cementitious material is diluted;

[0058] C3 is the carbon concentration in the supernatant after the dialysis membrane is diluted with deionized water and centrifuged, and K2 is the corresponding dilution multiple.

[0059] Test example

[0060] The present invention is used to measure LC 3 Adsorption of PCE by low carbon cement, LC 3 Low carbon cement mainly contains three components: cement clinker, calcined clay, and limestone powder. In this experiment, the cement pore solution used is an aqueous solution, in which the concentrations of various ions are: Ca 2+ 0.4g / L,Na + 2.25g / L,K + 7.1g / L,SO4 2- 8.29g / L,OH - 2.16g / L.

[0061] As a feasible implementation plan, the cement pore ion concentration range that can be adopted is Ca 2+0.2-0.6g / L,Na + 1.5-3g / L,K + 5-10g / L,SO4 2- 6-12g / L,OH - 2-2.5g / L.

[0062] PCE was made in the laboratory and synthesized by free radical copolymerization. It is a polycarboxylic acid-based water reducer. (Tang Ruifeng, Cui Suping, Yang Feihua, Wang Zhaojia, Wang Ziming. Effect of the amount of polycarboxylic acid copolymer on the nucleation and early strength of nano-CSH crystals during the synthesis process. Bulletin of the Chinese Ceramic Society. 2024, 43(09): 3128-3136+3202).

[0063] Specific detection implementation cases are as follows:

[0064] 18 mg of PCE solid was dissolved in 500 mL of cement pore solution. After PCE was fully dissolved, the total organic carbon concentration in the solution was measured (C0 = 48.32 mg / L). 1 g of each of the three components was weighed and spread evenly on the dialysis membrane, and the port was sealed with a dialysis membrane sealing clip. After the adsorption was completed, the total organic carbon concentration in the solution was measured (C1 = 47.09 mg / L). After washing with deionized water and centrifuging, the total organic carbon concentration in the supernatant (including free and unadsorbed PCE) was measured (C2 = 11.57 [水泥熟料] , 9.68 [煅烧粘土] , 18.36 [石灰石粉] mg / L), where the dilution factor K1 = 30.44 [水泥熟料] , 32.19 [煅烧粘土] , 36.35 [石灰石粉] At the same time, the organic carbon attached to the dialysis membrane was measured to obtain the total organic carbon content (C3 = 9.4 [水泥熟料] , 7.94 [煅烧粘土] , 8.78 [石灰石粉] mg / L), where the dilution factor K1 = 39.86 [水泥熟料] , 36.07 [煅烧粘土] , 39.89 [石灰石粉] .

[0065] Substituting the above data into the formula, the competitive adsorption amount of each component on PCE is:

[0066] Components cement clinker calcined clay limestone powder Adsorption capacity [mg / L] 0.61 0.71 0.50

[0067] The results show that in LC 3 In a low-carbon cement system, when cement clinker, calcined clay, and limestone powder are present simultaneously, the PCE adsorption capacity of calcined clay exceeds that of cement and then exceeds that of limestone powder. This device can clearly measure the adsorption capacity of each component under competitive adsorption conditions.

[0068] The study found that if C0 is too small, it will affect the detection effect, and if it is too high, it may lead to the non-existence of the concept of competitive adsorption. Therefore, the recommended range is 24-120 mg / L.

[0069] Currently, there is no device for measuring multi-component competitive adsorption due to the overlapping particle size distribution of cement binder components, making separation difficult after mixing. Conventional methods for measuring single-component adsorption can indirectly verify the accuracy of the results of this device.

[0070] The method is as follows: The TOC method for measuring the adsorption of PCE by a single component solid was used to conduct adsorption tests on the three components. The operation method refers to "Total organic carbon analyzer for testing. 30.0g of cement was mixed with 15.0g of PCEs solutions with different mass fractions in a 50mL centrifuge tube and centrifuged. The supernatant was filtered with a 0.45μm filter membrane. The filtrate was acidified with 0.1mol / L HCl to remove inorganic carbon. It was then diluted a certain number of times with deionized water, and the resulting solution was tested for total organic carbon. The same PCEs solution was used for measurement in the same way. The amount of PCEs adsorbed on the cement surface was obtained based on the difference in organic carbon content between the PCEs solution and the cement paste supernatant" (Yuan Jin, Sun Zhenping, Yang Haijing, et al. Effect and mechanism of PCEs molecular structure on cement paste viscosity [J / OL]. Building Materials Science).

[0071] The measured PCE adsorption order is: calcined clay > cement > limestone powder. This is consistent with the results obtained with this device. However, due to the varying PCE concentrations measured and the inability of existing methods to measure PCE adsorption affinity within the same PCE solution, this should not be used for complete comparison and should only be used as a reference.

[0072] Comparative Example 1

[0073] Using the same measurement method as in Example 2 and the test example, except that the adsorption time in step 2 was 1 minute, the results were: C0 = 48.25 mg / L, C1 = 48.36 mg / L. This is because the adsorption time was too short, and PCE had not yet adsorbed onto the surface of the cementitious material, resulting in a small difference between C0 and C1. The difference in total organic carbon content of the solution before and after adsorption was too small, making the amount of PCE adsorbed on the cementitious material impossible to calculate according to the formula.

[0074] The same determination method as in Example 2 and the test example was used, except that the adsorption time in step 2 was 11 minutes. The results were: cement clinker (1.02 mg / L), calcined clay (0.80 mg / L), and limestone powder (0.55 mg / L). This is because cement undergoes a hydration reaction when it comes into contact with water, and early hydration products such as hydrated tricalcium aluminate, ettringite, and calcium hydroxide are gradually generated, affecting the adsorption of PCE. As a result, there is a huge difference between its adsorption amount and the adsorption amount within 2-10 minutes due to the fact that calcined clay and limestone powder do not have the reaction conditions, so the adsorption amount does not change much.

[0075] Comparative Example 2

[0076] The same determination method as in Example 2 and the test example was used, except that the preparation method of the SCPS solution was "8 mg of PCE solid was dissolved in 500 mL of cement pore solution. After the PCE was fully dissolved, samples were taken to measure the total organic carbon concentration in the solution at this time (C0 = 23.03 mg / L) and the total organic carbon concentration of the solution after adsorption (and C1 = 23.29 mg / L)". The difference between C0 and C1 was too small to be further calculated using the formula.

[0077] The same determination method as in Example 2 and the test example was used, except that the preparation method of the SCPS solution was "56 mg of PCE solid was dissolved in 500 mL of cement pore solution. After the PCE was fully dissolved, a sample was taken to measure the total organic carbon concentration in the solution at this time (C0 = 130.09 mg / L)". The results were: cement clinker (1.91 mg / L), calcined clay (2.03 mg / L), and limestone powder (1.82 mg / L). It was calculated that the adsorption concentration of PCE in each component was close, and all had reached saturated adsorption, and there was no competitive adsorption phenomenon.

[0078] Compared to other devices, the present device for measuring competitive adsorption of multi-component gelling materials offers a simpler test method and can address the coexistence of multiple components in the gelling material during the adsorption process. After adsorption, the individual components can be easily separated and the amount of PCE molecules adsorbed on each component can be measured separately. When the rotor stirs the solution, a vortex is generated, causing the individual components placed in the measuring device to rotate. This rotation ensures that the individual components in the measuring device are fully exposed to the solution for adsorption, thus ensuring consistent solution concentration.

[0079] The measuring device provided by the present invention can be reused, and the amount of PCE dissolved and the rotor speed can be adjusted according to the required adsorption conditions. The rotor speed should be controlled within a certain range. The faster the speed, the faster the PCE dissolution rate. At the same time, during the experiment, the molecular motion is intensified, the molecular exchange rate inside and outside the dialysis membrane is accelerated, and PCE adsorption is faster. Therefore, too low a speed leads to insufficient PCE adsorption, and too high a speed will cause unstable operation of the device. Different PCE concentrations need to be set in the experiment for competitive adsorption tests. The amount of PCE dissolved must be less than the maximum adsorption amount of each component gelling material, and the speed setting should be controlled between 200rpm-800rpm.

[0080] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for determining competitive adsorption of multi-component gelling materials, characterized in that: Based on a competitive adsorption determination device of multi-component gelling materials, The measuring device for competitive adsorption of multi-component cementitious materials comprises a plurality of individual components of the measuring device and a test container, wherein the test container contains a concrete simulated pore solution containing a polycarboxylate water reducer, and the individual components of the measuring device are respectively placed in the test container; Each individual component of the measuring device includes a dialysis bag, which allows water and polycarboxylate water-reducing agent to pass through during the adsorption test and prevents the single component solid of the gel material from being dispersed into the solution in the test container; A single component of gelling material is placed in the dialysis bag; The steps include: Step 1: Pour the concrete simulation hole solution into the test container, weigh an appropriate amount of polycarboxylate water reducer and put it into the concrete simulation hole solution, set the magnetic stirrer speed between 200-800 rpm, stir until fully dissolved, and take a sample to measure the total organic carbon (TOC) concentration in the solution at this time, recorded as C0; In step 1, the total organic carbon concentration C0 in the simulated pore solution of concrete ranged from 24 to 120 mg / L; Step 2: Place the gelling materials in the dialysis bags of the measuring device, seal them, and place the multiple individual components of the assembled measuring device into the solution simultaneously. The components of the gelling materials fully absorb the polycarboxylate water-reducing agent under the action of the rotor stirring. After adsorption for 2-10 minutes, remove the gelling materials from the beaker. At this time, sample the solution in the beaker, acidify it, and then test the total organic carbon content, which is recorded as C1. In step 2, the ratio of the total amount of each group of cementitious materials added to the measuring device to the polycarboxylate superplasticizer in step 1 is: 1g of cementitious materials corresponds to 4-15mg of polycarboxylate superplasticizer; the amount of cementitious materials added to each group is equal; Step 3: After fully adsorbing the polycarboxylate water-reducing agent, each component is taken out from the dialysis bag, diluted with deionized water by a certain multiple K1, and centrifuged. At this time, the polycarboxylate water-reducing agent attached to the surface of the gelling material and not yet adsorbed is centrifuged to the supernatant. The supernatant is acidified and the total organic carbon content is measured, which is recorded as C2; the dialysis membrane is placed in a centrifuge tube, diluted with deionized water by a certain multiple K2, and centrifuged. The supernatant is acidified and the total organic carbon content is measured, which is recorded as C3.

2. The method for determining competitive adsorption of multi-component gelling materials according to claim 1, characterized in that: Each individual component of the assay device further comprises a clamp for sealing the dialysis bag.

3. The method for determining competitive adsorption of multi-component gelling materials according to claim 1, characterized in that: The test container is placed on a magnetic stirrer tray and a rotor is placed inside the test container to ensure consistency of solution concentration.

4. The method for determining competitive adsorption of multi-component gelling materials according to claim 1, characterized in that: The competitive adsorption results were calculated using the following formula: Where C is the final calculated concentration of polycarboxylate superplasticizer adsorbed on the surface of cementitious materials, mg / L; C0 is the initial carbon concentration of the solution, mg / L; C1 is the carbon concentration in the remaining solution after adsorption occurs, mg / L; C2 is the concentration of free carbon that has not been adsorbed on the surface of the cementitious material after the cementitious material is diluted, and K1 is the dilution multiple when the cementitious material is diluted; C3 is the carbon concentration in the supernatant after the dialysis membrane is diluted with deionized water and centrifuged, and K2 is the corresponding dilution multiple.

5. The method for determining competitive adsorption of multi-component gelling materials according to claim 1, characterized in that: The components of the multi-component cementitious material include cement clinker, calcined clay, limestone powder, granulated blast furnace slag powder, steel slag powder, fly ash, rice husk ash, silica fume, phosphorus slag powder, zeolite powder and composite mineral admixtures.

6. The method for determining competitive adsorption of multi-component gelling materials according to claim 5, characterized in that: The multi-component cementitious material comprises cement clinker, calcined clay and limestone powder.

7. The method for determining competitive adsorption of multi-component gelling materials according to claim 1, characterized in that: In step 1, the concrete simulation pore solution is an aqueous solution, wherein the ion concentration range is Ca 2+ 0.2-0.6 g / L, Na + 1.5-3 g / L, K + 5-10 g / L, SO4 2- 6-12 g / L, OH - 2-2.5 g / L.

Images