Method for nondestructive testing of hydration degree of cement grout
Through the NMR test method, the pore characteristics in the cement slurry are measured and the relaxation intensity distribution curve is constructed, which solves the complex and time-consuming problems of traditional detection methods, and achieves rapid and accurate non-destructive testing of the degree of hydration of the cement slurry.
Patent Information
- Application Number
- CN202411813763.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-02-14
AI Technical Summary
Traditional methods are used to detect the degree of hydration of cement slurry and are time-consuming, making it difficult to achieve efficient and accurate non-destructive testing.
Using the nuclear magnetic resonance test method, a relaxation intensity distribution curve was constructed by measuring the T2 signal of different size pores in the cement slurry and the initial magnetization vector M0, and the equivalent relaxation intensity was calculated to determine the degree of hydration.
It realizes rapid and accurate non-destructive testing of the degree of hydration of cement slurry, and can continuously and repeatedly test the same cement sample, avoiding the complexity and time-consuming of traditional methods.
Smart Images
Figure CN119438286A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of nondestructive testing of building materials, and in particular to a method for nondestructive testing of the hydration degree of cement slurry. Background Art
[0002] As a low-cost and high-performance inorganic cementitious material, cement has been widely used in practical projects such as grouting, grouting, water blocking and anti-seepage, and rock and soil reinforcement in the current fields of mining, tunnels, high-speed railways, construction, hydropower, etc.
[0003] At present, scholars have done a lot of research on the evolutionary properties of cement-based materials, including viscosity, water seepage rate, hydration process and other properties, which have an important impact on the application of practical engineering. The hydration process has research difficulties such as multiphase reaction, heterogeneity, and kinetic changes, but it is directly related to the overall performance of cement-based materials and the sustainability of engineering. Therefore, how to efficiently and accurately study the hydration process of cement-based materials has very important engineering significance for the correct evaluation of the performance of cement-based materials. However, traditional methods for characterizing the degree of cement hydration (including hydration heat, non-evaporable water, CH quantitative measurement and cement hydration kinetic model method) are quite complicated and time-consuming. Summary of the invention
[0004] The invention provides a method for non-destructively detecting the hydration degree of cement slurry. The method is simple and does not require damage to the cement slurry.
[0005] The present invention provides a method for non-destructively detecting the hydration degree of cement slurry, comprising the following steps:
[0006] (1) Performing nuclear magnetic resonance testing on cement slurry to obtain the initial magnetization vector M0 of pores of different sizes and T2 of pores of different sizes when the hydration time of the cement slurry is 0;
[0007] Arrange the T2 of pores of different sizes from small to large, and obtain the relaxation intensity distribution curve based on the T2 of pores of different sizes and the corresponding 0.37M0;
[0008] (2) Calculate the underlying area of the relaxation strength distribution curve to obtain the equivalent relaxation strength when the hydration time is 0 h.
[0009] (3) Repeat steps (1) to (2) to obtain the equivalent relaxation strength when the hydration time is T
[0010] (4) Calculate the hydration degree α of cement slurry when the hydration time is T according to formula (1):
[0011]
[0012] Preferably, during the nuclear magnetic resonance test, the cement slurry is placed in a silicon glass container and then vertically placed in a test coil used for the nuclear magnetic resonance test.
[0013] Preferably, the nuclear magnetic resonance test uses a CPMG sequence to collect data.
[0014] Preferably, the parameters of the nuclear magnetic resonance test include: waiting time is more than 1500 ms, echo time is more than 0.15 ms, repeated sampling times is more than 4, and the number of echoes is more than 4000.
[0015] Preferably, the waiting time is 1500-3000 ms, the echo time is 0.15-0.5 ms, the number of repeated sampling is 4-32 times, and the number of echoes is 4000-16000.
[0016] Preferably, the equivalent relaxation strength calculation formula is as shown in formula (2):
[0017]
[0018] Ts is the maximum T2 value among T2 of pores of different sizes, It is 0.37M0 corresponding to T2.
[0019] The present invention detects the hydration degree based on nuclear magnetic resonance, and can continuously and repeatedly test the same cement sample without damage, while other testing methods cannot distinguish such a difference in the water content in the slurry before setting. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 is the relaxation intensity distribution curve at different hydration times in Example 1;
[0021] Figure 2 is the area covered by the T2 signal intensity at different hydration times in Example 1;
[0022] Figure 3 It is the hydration degree of cement slurry with different hydration time in Example 1. DETAILED DESCRIPTION
[0023] The present invention provides a method for non-destructively detecting the hydration degree of cement slurry, comprising the following steps:
[0024] (1) Performing nuclear magnetic resonance testing on cement slurry to obtain the initial magnetization vector M0 of pores of different sizes and T2 of pores of different sizes when the hydration time of the cement slurry is 0;
[0025] Arrange the T2 of pores of different sizes from small to large, and obtain the relaxation intensity distribution curve based on the T2 of pores of different sizes and the corresponding 0.37M0;
[0026] (2) Calculate the underlying area of the relaxation strength distribution curve to obtain the equivalent relaxation strength when the hydration time is 0 h.
[0027] (3) Repeat steps (1) to (2) to obtain the equivalent relaxation strength when the hydration time is T
[0028] (4) Calculate the hydration degree α of cement slurry when the hydration time is T according to formula (1):
[0029]
[0030] In the present invention, 0.37M0 is the relaxation strength.
[0031] The present invention performs nuclear magnetic resonance testing on cement slurry to obtain initial magnetization vectors M0 of pores of different sizes and T2 of pores of different sizes when the hydration time of the cement slurry is 0;
[0032] The T2 of pores of different sizes are arranged from small to large, and the relaxation intensity distribution curve is obtained based on the T2 of pores of different sizes and the corresponding 0.37M0.
[0033] In the present invention, during the nuclear magnetic resonance test, the cement slurry is preferably placed in a silicon glass container and then vertically placed in a test coil used for the nuclear magnetic resonance test. The use of a silicon glass container can effectively avoid interference with the nuclear magnetic resonance test.
[0034] In the present invention, the NMR test preferably uses a CPMG sequence to collect data; the parameters of the NMR are: waiting time is more than 1500ms, echo time is more than 0.15ms, repeated sampling times is more than 4, and the number of echoes is more than 4000.
[0035] The waiting time is more preferably 1500-3000ms. In a specific embodiment of the present invention, the waiting time may be 1500ms, 2000ms, 2500ms or 3000ms;
[0036] The echo time is more preferably 0.15 to 0.5 ms. In a specific embodiment of the present invention, the echo time may be 0.15 ms, 0.2 ms, 0.3 ms, 0.4 ms or 0.5 ms;
[0037] The number of repeated sampling is more preferably 4 to 32 times. In a specific embodiment of the present invention, the number of repeated sampling can be 4 times, 8 times, 12 times, 16 times, 20 times, 24 times, 28 times or 32 times;
[0038] The number of echoes is more preferably 4000-16000. In a specific embodiment of the present invention, the number of echoes may be 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000 or 16000.
[0039] After obtaining the relaxation strength distribution curve, the present invention calculates the underlying area of the relaxation strength distribution curve to obtain the equivalent relaxation strength when the hydration time is 0h.
[0040] In the present invention, the calculation formula of the equivalent relaxation strength is preferably as shown in formula (2):
[0041]
[0042] Ts is the maximum T2 value among T2 of pores of different sizes, It is 0.37M0 corresponding to T2.
[0043] Repeat steps (1) to (2) to obtain the equivalent relaxation strength when the hydration time is T
[0044] (4) According to formula (1), the hydration degree α of cement slurry at hydration time t is calculated as:
[0045]
[0046] The method for non-destructive detection of cement slurry hydration degree provided by the present invention is described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.
[0047] Example 1
[0048] (1) Prepare ultrafine silicate cement (K1000 mesh ultrafine cement slurry (D50≤5μm, D90≤13μm)) with a water-cement ratio of 0.6, take 10 mL and put it into a silica glass test tube, vertically put it into a low-field nuclear magnetic resonance analysis system (MacroMR12-150H-I low-field nuclear magnetic resonance rock seepage process real-time monitoring system produced by Suzhou Newmai Analytical Instrument Co., Ltd.), use the CPMG sequence, set the test parameters: TW = 1500ms, TE = 0.15ms, NS = 4, NECH = 4000, and obtain the initial magnetization vector M at hydration time of 0h, 2h, 6h, 12h, 19h, 26h and 37h, respectively.0i and T2 with different pore sizes;
[0049] The T2 of pores of different sizes are arranged from small to large, and the relaxation intensity distribution curves at hydration times of 0h, 2h, 6h, 12h, 19h, 26h and 37h are obtained according to the T2 of pores of different sizes and the corresponding 0.37M0. The results are shown in Figure 1 shown.
[0050] Calculate the area under the relaxation intensity distribution curve for different hydration times. The results are as follows: Figure 2 shown.
[0051] Depend on Figure 2 It can be seen that the equivalent relaxation strength gradually decreases with the hydration time, thus obtaining the equivalent relaxation strength of different hydration times.
[0052] (3) According to formula (2), the hydration degree of cement slurry measured at 2h, 12h, 19h, 26h and 37h is calculated. The results are as follows: Figure 3 shown.
[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for non-destructive detection of the degree of hydration of cement slurry, characterized in that: The following steps are involved: (1) Performing nuclear magnetic resonance testing on cement slurry to obtain the initial magnetization vector M0 of pores of different sizes and T2 of pores of different sizes when the hydration time of the cement slurry is 0; Arrange the T2 of pores of different sizes from small to large, and obtain the relaxation intensity distribution curve based on the T2 of pores of different sizes and the corresponding 0.37M0; (2) Calculate the underlying area of the relaxation strength distribution curve to obtain the equivalent relaxation strength when the hydration time is 0 h. (3) Repeat steps (1) to (2) to obtain the equivalent relaxation strength when the hydration time is T (4) Calculate the hydration degree α of cement slurry when the hydration time is T according to formula (1):
2. The method according to claim 1, characterized in that During the nuclear magnetic resonance test, the cement slurry is placed in a silicon glass container and then vertically placed in a test coil used for the nuclear magnetic resonance test.
3. The method according to claim 1, characterized in that The nuclear magnetic resonance test uses a CPMG sequence to collect data.
4. The method according to claim 1 or 3, characterized in that: The parameters of the nuclear magnetic resonance test include: waiting time is more than 1500ms, echo time is more than 0.15ms, repeated sampling times is more than 4, and the number of echoes is more than 4000.
5. The method according to claim 4, characterized in that The waiting time is 1500-3000 ms, the echo time is 0.15-0.5 ms, the number of repeated sampling is 4-32 times, and the number of echoes is 4000-16000.
6. The method according to claim 1, characterized in that The calculation formula of the equivalent relaxation strength is shown in formula (2): Ts is the maximum T2 value among T2 of pores of different sizes, It is 0.37M0 corresponding to T2.