Rapid detection method for water reducing performance of water reducing type polycarboxylic acid water reducing agent

Abstract

The invention discloses a method for rapidly detecting the water reducing performance of a water reducing type polycarboxylic acid water reducing agent, and relates to the technical field of polycarboxylic acid water reducing agents. The rapid detection method comprises the following steps: (1) detecting the final test viscosity eta of a product after the reaction of a sample is completed by adopting online viscosity detection equipment with an automatic temperature compensation function; (2) calculating the viscosity average molecular weight M eta and the monomer conversion rate alpha by adopting a viscosity average molecular weight calculation formula and a monomer conversion rate calculation formula according to the test viscosity eta; and (3) comparing the viscosity average molecular weight M eta and the monomer conversion rate alpha with the normal performance range of the product, and judging the water reducing performance of the product. According to the method, the viscosity of the polycarboxylate superplasticizer is tested on line, the water reducing performance of the polycarboxylate superplasticizer is rapidly judged according to the viscosity, and a new thought is provided for detection of the water reducing performance.

Description

Technical Field

[0001] The present invention relates to the technical field of polycarboxylate water reducers, and particularly relates to a rapid detection method for the water reduction performance of water-reducing polycarboxylate water reducers. Background Art

[0002] Polycarboxylate water reducers are widely used due to their low dosage, high water reduction rate, excellent slump retention performance, low shrinkage, which can significantly improve the workability of concrete, improve construction efficiency and quality, greatly reduce the water-binder ratio, enhance the strength and durability of concrete, extend the service life of concrete structures, save cement consumption, and improve the utilization rate of industrial waste residues. Due to the diversity of their structures, polycarboxylate water reducers are of various types, and their detection methods are also different. Currently, the relatively subjective and cumbersome production detection links do not match the increasing usage of polycarboxylate water reducers. Usually, after production, quality control personnel take samples from the reaction kettle and then go to the laboratory for a series of tests such as the fluidity of neat cement paste, solid content, and density. There are many subjective factors affecting the detection process, with large fluctuations, which may cause errors in detection data and affect product quality control. At the same time, a series of tests take a long time and require a large number of personnel, which to a certain extent affects the production efficiency of admixtures. Currently, there is an urgent need to develop an efficient, fast, and accurate detection method.

[0003] Viscosity, as an important performance index of polymers, is a direct manifestation of polymer molecular weight, monomer conversion rate, solid content, etc. The performance of polymers can be indirectly judged through viscosity. At the same time, the measurement methods of viscosity are relatively diverse, and the reading can be directly obtained using a viscometer. Therefore, it is potentially valuable to use viscosity as a medium for rapid detection of the water reduction performance of polycarboxylate water reducers. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a rapid detection method for the water reduction performance of water-reducing polycarboxylate water reducers. By online testing the viscosity of polycarboxylate water reducers and quickly determining the water reduction performance of polycarboxylate water reducers based on the viscosity, a new idea is provided for the detection of water reduction performance.

[0005] The technical solution for the present invention to solve the above technical problems is as follows: A rapid detection method for the water reduction performance of water-reducing polycarboxylate water reducers is provided, including the following steps:

[0006] (1) Using an online viscosity detection device with temperature automatic compensation function, detect the final test viscosity η of the product after the sample reaction is completed;

[0007] (2) According to the test viscosity η, use the viscosity-average molecular weight calculation formula and the monomer conversion rate calculation formula to calculate the viscosity-average molecular weight M η and the monomer conversion rate α;

[0008] Formula for viscosity-average molecular weight: Mη = 902.15η0.925;

[0009] Formula for monomer conversion rate: α = -1.1×10-5 η 2 + 0.00825 η -0.5621;

[0010] (3) Compare the viscosity-average molecular weight M η and the monomer conversion rate α with the normal performance range of the product to judge the water-reducing performance of the product.

[0011] Furthermore, in step (1), the viscosity at 40 °C under temperature compensation is detected.

[0012] Furthermore, in step (3), the normal performance range of the product is obtained by the following method: Take production samples of multiple batches of products, conduct viscosity tests at a temperature of 40 °C, and simultaneously obtain the actual viscosity-average molecular weight and monomer conversion rate of the production samples. Eliminate the data of unqualified production samples to obtain the normal performance range of the product.

[0013] The present invention has the following beneficial effects:

[0014] 1. The viscosity online detection method adopted by the present invention can directly read the data from the equipment, quickly convert the viscosity of the detection sample into the corresponding viscosity-average molecular weight and monomer conversion rate, so as to quickly obtain whether the water-reducing performance of the sample meets the requirements, avoiding cumbersome operation processes, greatly shortening the detection time, and reducing the labor input at the same time.

[0015] 2. The rapid water-reducing performance detection method provided by the present invention converts the viscosity-average molecular weight and monomer conversion rate by directly reading the viscosity data, avoiding human errors and greatly improving the detection accuracy.

[0016] 3. The rapid water-reducing performance detection method provided by the present invention avoids the tests of the fluidity of cement paste and the water-reducing rate of concrete, reduces the use of building materials, and does not produce noise pollution. It is economical and environmentally friendly and meets the requirements of green production.

[0017] 4. The rapid water-reducing performance detection method provided by the present invention automatically detects the viscosity by the equipment and calculates and converts it into the corresponding viscosity-average molecular weight and monomer conversion rate, realizing the intelligentization of production detection, high efficiency and energy saving. It can detect multiple batches of samples at the same time, greatly improving the market competitiveness of the enterprise. Specific embodiments

[0018] The principles and features of the present invention are described below. The examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. In the examples, where specific conditions are not specified, conventional conditions or manufacturer-recommended conditions were used. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially.

[0019] Example 1

[0020] Take a sample of a water-reducing polycarboxylate superplasticizer (hereinafter referred to as Sample A) as an example. The specifications of Sample A meet the requirements of GB8076-2008, "Concrete Admixtures." The fluidity of cement paste is based on GB / T8077-2012, "Test Method for Homogeneity of Concrete Admixtures."

[0021] The preparation of a water-reducing polycarboxylate water-reducing agent sample comprises the following steps:

[0022] (1) Synthesis of water-reducing polycarboxylate water-reducing agent: In a glass reactor equipped with a thermometer and a stirrer, 360 parts of isopentanol polyoxyethylene ether with a molecular weight of 2400 and 300 parts of deionized water were added in sequence and stirred until fully dissolved to obtain a reactant base solution;

[0023] (2) 30 parts of acrylic acid, 1 part of mercaptoethanol and 33 parts of deionized water were mixed to prepare a mixed solution A; 0.5 parts of L-ascorbic acid and 46 parts of deionized water were mixed to prepare a mixed solution B;

[0024] (3) Under stirring, add 2 parts of hydrogen peroxide to the reactant base liquid, first add mixed solution B dropwise, and then add mixed solution A dropwise after 2 minutes. Mixed solution A is added dropwise for 100 minutes, and mixed solution B is added dropwise for 120 minutes. After the addition is completed, keep warm for 60 minutes, add water to dilute to a solid content of 50%, and obtain a water-reducing polycarboxylate water reducer (sample A).

[0025] At the same time, samples with different viscosity-average molecular weights were obtained by changing the amount of mercaptoethanol, which was 0.5g, 1g, 1.5g, 2g, 2.5g, 3g, 3.5g, and 4g;

[0026] The samples with different polyether macromonomer conversion rates were terminated by adding a polymerization inhibitor (hydroquinone) in advance, and the termination times were 20 min, 40 min, 60 min, 80 min, 100 min, 120 min, 150 min, and 180 min respectively;

[0027] The viscosity average molecular weight and viscosity data at 40°C of samples with different mercaptoethanol dosages were tested. The specific data are shown in Table 1.

[0028] Table 1 Viscosity average molecular weight and viscosity of sample A prepared with different amounts of mercaptoethanol

[0029]

[0030] According to the equation η = kM η α The viscosity-average molecular weight calculation formula is obtained by fitting: Mη = 902.15η0.925.

[0031] Similarly, the viscosity-average molecular weight and viscosity data at 40 °C of samples with different reaction times are detected. The specific data are shown in Table 2;

[0032] Table 2 Conversion rate and viscosity of sample A polyether macromonomer prepared at different reaction times

[0033] Reaction time / min Viscosity / mPa·s Conversion rate of polyether macromonomer / % 20 89 8.23 40 123 28.69 60 178 55.15 80 211 67.31 100 246 80.70 120 274 88.93 180 307 94.02 240 321 95.14

[0034] Taking the viscosity and monomer conversion rate corresponding to different reaction times as sites, function fitting is carried out, and the goodness of fit is judged. The monomer conversion rate calculation formula:

[0035] α = -1.1×10-5η2 + 0.00825η - 0.5621.

[0036] Example 2

[0037] 1. Determination of the normal performance range of the product: Samples A of multiple batches are taken for production, including some samples with unqualified water-reducing performance. At 40 °C, viscosity tests are carried out to determine the viscosity fluctuation range of samples with qualified water-reducing performance. Qualified water-reducing performance means that the difference between the fluidity of cement paste and the reference is ≤ 15 mm; the specific data are shown in Table 3.

[0038] Table 3 Fluidity of cement paste, viscosity, molecular weight of multiple batches of sample A corresponding to water-reducing performance

[0039]

[0040]

[0041]

[0042] As can be seen from Table 3, when the viscosity fluctuation range of the products with qualified water-reducing performance is 301 - 349 mPa·s, the actual fluctuation range of their viscosity-average molecular weight is 176701 - 202704, and the actual fluctuation range of monomer conversion rate is 92.18% - 98.98%. For the samples with poor water-reducing performance, the molecular weight or monomer conversion rate is outside the range. Among them, since the synthesis of polycarboxylate water-reducing agent is free radical polymerization, without changing the reaction conditions, the molecular weight will not change significantly. Samples No. 48 - 50 have too high molecular weight due to the self-polymerization of functional small monomers, and samples No. 46 - 47 have insufficient degree of polymerization. That is, the qualification of the samples can be judged by whether the viscosity-average molecular weight of the samples is within the range of 176701 - 202704 and whether the monomer conversion rate is within the range of 92.18% - 98.98%.

[0043] 2. Sample detection: Use an on-line viscosity detection device (with automatic temperature compensation) to detect the final test viscosity η of the product after the sample reaction is completed. Calculate the viscosity-average molecular weight and monomer conversion rate, compare with the database to determine whether the viscosity-average molecular weight and monomer conversion rate belong to the normal performance range, and then quickly judge the initial water-reducing performance of the water-reducing product. At the same time, conduct a review through the detection of the fluidity of cement paste. The specific data is shown in Table 4.

[0044] Table 4 Production data of sample A and determination of water-reducing performance

[0045]

[0046]

[0047] As can be seen from Table 4, when using the rapid detection method for the water-reducing performance of the water-reducing polycarboxylate water-reducing agent of the present invention to determine the qualification of water-reducing performance, the viscosity can be converted into the viscosity-average molecular weight and monomer conversion rate, and the water-reducing performance of the polycarboxylate water-reducing agent can be quickly judged. And the result is consistent with the result of the detection of the fluidity of cement paste, indicating that the water-reducing performance of the polycarboxylate water-reducing agent can be quickly detected by this method to obtain accurate water-reducing performance results. At the same time, the reasons for the products with poor water-reducing performance can be preliminarily judged according to the viscosity-average molecular weight and monomer conversion rate obtained by viscosity conversion.

[0048] Meanwhile, the rapid detection method for the water-reducing performance of the water-reducing polycarboxylate water-reducing agent of the present invention can replace the detection method of the fluidity of cement paste, reduce the consumption of building materials such as cement, and at the same time, as an intelligent detection, effectively reduce the labor cost, improve work efficiency, and practice intelligent manufacturing.

[0049] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A rapid detection method for the water-reducing performance of water-reducing polycarboxylate superplasticizer, characterized in that, It includes the following steps: (1) Use an on-line viscosity detection device with automatic temperature compensation function to detect the final test viscosity η of the product after the sample reaction is completed; (2) Calculate the viscosity-average molecular weight M and the monomer conversion rate α according to the measured viscosity η using the viscosity-average molecular weight calculation formula and the monomer conversion rate calculation formula. η and the monomer conversion rate α; Formula for calculating viscosity-average molecular weight: Mη = 902.15η0.925; Formula for calculating monomer conversion rate: α＝-1.1×10-5 η 2+0.00825 η -0.5621； (3) Compare the viscosity-average molecular weight M η and the monomer conversion rate α with the normal performance range of the product to judge the water-reducing performance of the product.

2. The rapid detection method for water-reducing performance of water-reducing polycarboxylate water reducer according to claim 1, characterized in that In step (1), the viscosity at 40°C under temperature compensation is detected.

3. The rapid detection method for water-reducing performance of water-reducing polycarboxylate water reducer according to claim 1, characterized in that, In step (3), the normal performance range of the product is obtained by the following method: Take production samples of multiple batches of products, conduct viscosity tests at 40°C, and simultaneously obtain the actual viscosity-average molecular weight and monomer conversion rate of the production samples. Eliminate the data of unqualified production samples to obtain the normal performance range of the product.

4. The rapid detection method for water-reducing performance of water-reducing polycarboxylate water reducer according to claim 1, wherein The qualified water-reducing performance of the product means that the difference between the fluidity of cement paste and the reference is ≤ 15 mm.

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