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Method for measuring bleeding property of cement paste employing hydrogen proton low-field nuclear magnetic resonance technique

A low-field nuclear magnetic resonance and cement slurry technology, applied in the field of building materials, can solve the problems of impermeability, frost resistance and corrosion resistance, the actual water-cement ratio of fresh concrete, the actual volume and the adverse effects of volume stability, weak layer The problem of uneven quality, to achieve the effect of accurate detection

Active Publication Date: 2015-04-29
HUNAN CSCEC5B CONCRETE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Taking concrete as an example, the steps of mixing, molding and curing in the preparation process all have an important impact on its internal structure and macroscopic properties, especially the concrete mixture in the plastic stage, often due to the cementitious material system itself and excessive vibration Bleeding due to various reasons, such as water-cement ratio, actual volume and volume stability of freshly mixed concrete will be adversely affected, and it will cause the emergence of weak layers and uneven quality of concrete after hardening, which will lead to impermeability, frost resistance and Deterioration of performance such as corrosion resistance

Method used

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  • Method for measuring bleeding property of cement paste employing hydrogen proton low-field nuclear magnetic resonance technique
  • Method for measuring bleeding property of cement paste employing hydrogen proton low-field nuclear magnetic resonance technique
  • Method for measuring bleeding property of cement paste employing hydrogen proton low-field nuclear magnetic resonance technique

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] Test material: cement is P.O 52.5 grade, specific surface area is 396.5 kg / m 3 , the water consumption for the standard consistency is 141g, the initial setting is 1h20min, the final setting is 3h42min, the water-cement ratio used for the example test is 0.5, the expansion loss is 32% in 120min, and 67% in 300min. The test equipment and parameters are: MICRO-MR20 nuclear magnetic resonance analyzer is used for the test, CPMG pulse sequence is used, the number of echoes is n=18000, the echo time is 2τ=100μs, each CPMG signal scans m=8 times on average, and Repeat decay. The resampling waiting time TW is 18000ms. According to the calculation method mentioned above, the bleeding coefficient can be obtained.

[0041] figure 1 and figure 2 T is the cement paste with different hydration time 2 distribution and T representing the bleeding peak 2 curve.

[0042] Substitute the data in the figure into the calculation formula (2) to obtain the bleeding coefficient of the ...

Embodiment 2

[0046] Test material: cement is P.O 52.5 grade, specific surface area is 396 m 3 / kg, the water consumption of the standard consistency is 141g, the experiment controls the fluidity (200mm±5mm), adjusts the water-cement ratio of the slurry for the bleeding test, and the water-cement ratio of the slurry for the bleeding test is 0.44. The nuclear magnetic resonance test equipment and parameters are: MICRO-MR20 nuclear magnetic resonance analyzer is used for the test, CPMG pulse sequence is used, the number of echoes is n=18000, the echo time is 2τ=100μs, and each CPMG signal scans m=8 times on average , and repeated decay. The resampling waiting time TW is 18000ms. Will image 3 The data in is calculated by formula (2) to get the bleeding coefficient K was 1.65%. Test the bleeding rate according to JC / T 2153-2012 "Test Method for Bleeding of Cement" to get the bleeding rate B w was 1.61%.

Embodiment 3

[0048] Test material: cement is P.O 32.5 grade, specific surface area is 384 m 3 / kg, the water consumption of the standard consistency is 113g, the experiment controls the fluidity (200mm±5mm), adjusts the water-cement ratio of the slurry for the bleeding test, and the water-cement ratio of the slurry for the bleeding test is 0.41. The nuclear magnetic resonance test equipment and parameters are: MICRO-MR20 nuclear magnetic resonance analyzer is used for the test, CPMG pulse sequence is used, the number of echoes is n=18000, the echo time is 2τ=100μs, and each CPMG signal scans m=8 times on average , and repeated decay. The resampling waiting time TW is 18000ms. Will Figure 4 The data in is calculated by formula (2) to get the bleeding coefficient K 2.25%. Test the bleeding rate according to JC / T 2153-2012 "Test Method for Bleeding of Cement" to get the bleeding rate B w was 2.18%.

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Abstract

The invention belongs to the technical field of building materials, and particularly relates to a method for measuring bleeding property of cement paste employing a hydrogen proton low-field nuclear magnetic resonance technique. The method comprises the following steps: adding water to cement, and stirring evenly; packing the obtained paste into a test tube free of an interference signal on a nuclear magnetic resonator, standing and then testing an attenuation curve of transverse relaxation time (T2); carrying out inversion calculation on the collected T2 attenuation curve through software (InvFit) and thus obtaining a distribution curve of the T2 value at different relaxation time, which indirectly reflects relative quantity of water in the paste at different relaxation time at testing time; and obtaining a bleeding coefficient of the cement paste by calculation of the curve peak value area of T2. According to the method, the test can be relatively simply finished; the breeding degree of the cement paste is relatively accurately and continuously reflected; the bleeding property of the cement paste can be subjected to instant tracking testing by the method; the method is convenient, fast, time-saving and efficient; and continuous in-situ test can also be carried out on the cement paste.

Description

technical field [0001] The invention belongs to the technical field of building materials, and in particular relates to a method for measuring the bleeding property of cement paste by using a hydrogen proton low-field nuclear magnetic resonance technique. Background technique [0002] Cement-based materials are engineering materials with cement as the main cementitious material, among which concrete and mortar are the most common cement-based materials and are widely used in practical engineering. Taking concrete as an example, the steps of mixing, molding and curing in the preparation process all have an important impact on its internal structure and macroscopic properties, especially the concrete mixture in the plastic stage, often due to the cementitious material system itself and excessive vibration Bleeding due to various reasons, such as water-cement ratio, actual volume and volume stability of freshly mixed concrete will be adversely affected, and it will cause the em...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N24/08
Inventor 孙振平冀言亮李春景水亮亮杨旭刘毅
Owner HUNAN CSCEC5B CONCRETE
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