Method for measuring length of alkali activity test piece

Abstract

The invention discloses a method for measuring the length of an alkali activity test piece. The method comprises the following steps: S1, taking out and cleaning a maintained test piece; s2, placing the test piece in a measuring frame, releasing a lateral extrusion mechanism which is fixed in advance and can be elastically reset, enabling the lateral extrusion mechanism to instantly move under the action of elastic force, and extruding and attaching the side surface of the test piece to the fixed reference baffle plate; and S3, contacting the measuring instrument with the upper end of the test piece and reading. Wherein the total operation time from the time when the test piece leaves the alkali liquor to the time when reading is completed is controlled within 15 + / -5 seconds. According to the invention, the key step of releasing the elastic extrusion mechanism to realize instantaneous automatic alignment is combined with strict time window control, so that the rapidness, consistency and high precision of test piece positioning are ensured, and the measurement error of the test piece caused by environmental change is obviously inhibited. The method is particularly suitable for being cooperatively used with a special measuring device with a corresponding structure, a single person can complete single measurement within seconds, and the testing efficiency and the result reliability are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of building material performance testing technology, specifically to a method for measuring the length of alkali-reactive specimens used to determine the alkali-aggregate reaction expansion rate of concrete or mortar, and in particular, a length measurement method that can be performed quickly, accurately, and by a single person. Background Technology

[0002] Alkali-aggregate reaction is a significant cause of concrete durability degradation. In laboratory assessments of aggregate alkali-aggregate reactivity, specimens of a specified shape are typically cured in a high-temperature alkaline solution, and their length changes are measured periodically. The accuracy and repeatability of these measurements directly impact the evaluation of aggregate alkali-aggregate reactivity.

[0003] Currently, methods for measuring the length of alkali-reactive specimens typically employ an outside micrometer or a fixed clamp equipped with a dial indicator. These methods have the following inherent drawbacks:

[0004] 1. Cumbersome and Time-Consuming Operation: During measurement, repeated adjustments, alignment, and clamping of the specimen are required, making the entire process time-consuming. According to relevant testing standards (such as the Chinese industry standard SL / T352-2020), the total time from removing the specimen from the constant-temperature alkaline solution to completing the measurement should be controlled within 15±5 seconds; otherwise, the slight expansion and contraction of the specimen due to temperature and humidity changes will introduce significant errors. Traditional methods, operated by a single person, are unlikely to meet this stringent time requirement.

[0005] 2. Low alignment accuracy: The specimen needs to be in close contact with the measurement reference surface to eliminate gaps. Traditional manual alignment methods cannot guarantee that the specimen and the reference surface are in consistent contact during each measurement, resulting in random gaps, large fluctuations in measurement values, and poor repeatability.

[0006] 3. Inefficiency: A set of tests usually includes multiple specimens. Traditional measurement methods are inefficient, labor-intensive, and difficult to meet the needs of batch testing.

[0007] To address the aforementioned issues, Chinese utility model patent application number 201420731032.4, entitled "Measuring Device for the Length of Alkali-Active Specimens," discloses a dedicated measuring device. This device, by incorporating a resiliently resettable compression plate and a reference baffle, aims to assist in rapid specimen alignment. However, this utility model patent only protects the structure of the device itself. To most effectively and optimally utilize this device (or a device with equivalent functionality), translating its structural advantages into stable, reliable, and high-precision measurement results, a standardized operating method perfectly complementing it is required. Currently, there is a lack of a systematic measurement method that integrates with such dedicated devices, fundamentally resolving the challenges of measurement speed, accuracy, and consistency from a procedural perspective. Summary of the Invention

[0008] The present invention aims to solve the above-mentioned technical problems by providing a method for measuring the length of alkali-active specimens.

[0009] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a method for measuring the length of an alkali-active specimen, comprising the following steps: S1. Specimen preparation: Take out the specimen that has been cured in constant temperature alkaline solution and clean its surface and the probes at both ends; S2. Specimen loading and alignment: Place the specimen between the upper and lower reference surfaces within the measuring frame; release a pre-fixed, elastically resettable lateral compression mechanism, allowing the mechanism to move under elastic force, pressing one side of the specimen against a fixed reference baffle and ensuring close contact. S3. Data reading: Make the probe of a measuring instrument contact the upper end of the specimen and read the specimen length change value displayed by the measuring instrument; The total operation time from the moment the specimen leaves the constant-temperature alkaline solution in step S1 to the completion of the reading in step S3 is controlled within 15 ± 5 seconds.

[0010] Furthermore, the total operation time is 3 to 5 seconds.

[0011] Furthermore, in step S1, the cleaning is completed by wiping with an absorbent material.

[0012] Further, step S2 specifically includes: lifting the measuring rod of the measuring instrument with one hand to move the upper reference surface upward, and placing the specimen into the measuring frame with the other hand and positioning it between the upper reference surface and the lower reference surface; subsequently, releasing the pre-fixed lateral compression mechanism.

[0013] Furthermore, the lateral compression mechanism is temporarily fixed by a locking element, and the release action is to unlock the locking element.

[0014] Furthermore, the appendix to the specification of the utility model patent, such as application number 201420731032.4, can be adopted. Figure 1 , 2 The measuring device shown implements the method. For brevity, the specification and drawings of this patent are incorporated herein by reference. The locking element is a zipper, the lateral compression mechanism is a compression plate, and the reference baffle is a reference baffle.

[0015] Furthermore, the measuring instrument is a dial indicator.

[0016] Furthermore, the method is used to measure the length change rate of concrete or mortar specimens in the alkali-aggregate reaction experiment; in step S1, the constant temperature alkali solution is a 1 mol / L NaOH solution, and the curing temperature is 80±2℃.

[0017] Compared with the prior art, the present invention has the following significant advantages: 1. By using the "release of the lateral compression mechanism to achieve instantaneous automatic alignment," the specimen is quickly and consistently pressed against the reference baffle using elastic force (such as spring force), completely eliminating random gaps and angular deviations caused by manual specimen placement. This step ensures a high degree of consistency in the spatial relationship between the specimen and the reference surface during each measurement, fundamentally improving the repeatability of the measurement.

[0018] 2. The operation process is standardized and modularized into several consecutive actions: "wiping - placing - releasing - reading." By employing a two-handed coordinated operation—lifting the measuring rod with one hand and placing the specimen with the other—auxiliary time is significantly reduced. The entire process can be completed within 3-5 seconds, far below the standard limit of 15±5 seconds. This minimizes measurement errors caused by thermal expansion and contraction or moisture evaporation after the specimen leaves the constant temperature environment, thus ensuring the authenticity and accuracy of the data.

[0019] 3. The entire methodology is rationally designed with smooth transitions between actions, requiring no assistance from a second person. The operator can continuously and stably complete all measurements of a set of specimens, avoiding systematic errors caused by differing operating habits among multiple people, thus improving work efficiency and the reliability of results. Attached Figure Description

[0020] The specific implementation of the method of this invention can be combined with a measuring device capable of performing the corresponding function. To more clearly illustrate the device structure upon which the preferred embodiment of this method relies, the drawings in the specification of utility model patent application number 201420731032.4 are referenced herein. Wherein:

[0021] Figure 1 This is a flowchart of the present invention.

[0022] Figure 2 This is a schematic diagram of the main view structure of an existing measuring device in the background art.

[0023] Figure 3 This is a schematic diagram of the left-side structure of an existing measuring device in the background art.

[0024] As shown in the figure: 1. Dial indicator; 2. Upper fixing nut; 3. Inner fixing clip; 4. Upper measuring plate; 5. Reference baffle; 6. Lower measuring plate; 7. Lower fixing nut; 8. Extrusion plate; 9. Side plate; 10. Spring; 11. Slot; 12. Zipper; 13. Specimen; 14. Screw. Detailed Implementation

[0025] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0026] This solution achieves rapid and high-precision measurement of the length change of alkali-active specimens through a standardized operating procedure deeply integrated with the specific device structure and strict time control. The following embodiments use the measuring device from the referenced document (application number 201420731032.4) as an example tool for implementation, to facilitate understanding. Those skilled in the art will understand that any measuring device capable of "providing upper and lower reference planes," "having a releasable elastic lateral compression function," and "having a fixed reference baffle" can be used to implement the core steps of the method of this invention.

[0027] This embodiment provides a complete method for measuring the length of alkali-reactive specimens, which is particularly suitable for measuring mortar rod specimens for alkali-aggregate reaction tests according to the "Test Procedure for Hydraulic Concrete".

[0028] Preparations before measurement: 1. Equipment preparation: Refer to Figure 2 and Figure 3 Place the measuring device on a stable workbench. Loosen the lower fixing nut 7 and adjust the height of the lower measuring plate 6 by rotating the screw 14, ensuring that the distance between it and the upper measuring plate 4 is slightly greater than the standard length of the test piece 13. Then, tighten the lower measuring plate 6 with the lower fixing nut 7. Ensure that the compression plate 8 is reliably fixed to the side plate 9 via the zipper 12, in a "pre-tightened" or "ready to release" state. Check that the dial indicator 1 is securely installed and perform zero-point calibration.

[0029] 2. Specimen preparation: Remove specimen 13, along with its sealed curing container, from the constant temperature water bath while it is being cured in a 1 mol / L NaOH solution at 80±2℃, and move it to the side of the measuring device for later use. Prepare a dry, clean towel or cotton cloth.

[0030] Measurement operation steps: S101. Specimen Removal and Cleaning (corresponding to step S1 in claim): Open the curing chamber and quickly remove one specimen 13 using clamps or gloved hands. Immediately and quickly wipe the surface of the specimen 13 and the metal probes at both ends with a towel to remove residual alkali and moisture. This step should be done quickly, usually within 1-2 seconds.

[0031] The rapid wiping is to reduce errors caused by the liquid film on the specimen surface and to buy time for subsequent "rapid alignment". The cleaned metal probes at both ends of specimen 13 will contact the upper test plate 4 and the lower test plate 6 of the device, respectively. Cleaning ensures the reliability of the contact surfaces.

[0032] S102. Specimen loading and automatic alignment (preferred method corresponding to step S2 of claim): This step is performed by two hands working together.

[0033] The operator holds the middle of the specimen 13 with their non-dominant hand (e.g., left hand); at the same time, they gently lift the measuring rod of the dial indicator 1 upwards with their dominant hand (e.g., right hand), causing the upper measuring plate 4 connected to it to move upwards, making enough space inside the measuring frame; then, the left hand quickly places the specimen 13 vertically into the space enclosed by the reference baffle 5, the compression plate 8, the upper measuring plate 4, and the lower measuring plate 6, so that the lower end of the specimen 13 contacts the lower measuring plate 6; then, the right hand releases the measuring rod of the dial indicator 1, so that the upper measuring plate 4 gently falls on the upper end of the specimen 13 under its own weight (at this time, the dial indicator pointer begins to rotate, but is not stable); the right hand immediately unzips the zipper 12 that fixes the compression plate 8 to the side plate 9.

[0034] The moment the zipper 12 is unzipped, the previously compressed spring 10 (installed in the slot 11) immediately releases its elastic force, pushing the compression plate 8 towards the reference baffle 5. The compression plate 8 presses one side of the specimen 13 tightly, smoothly, and without gaps against the fixed reference baffle 5. This process utilizes the elastic energy storage and rapid release characteristics of the spring to achieve instantaneous constant force alignment that is difficult to achieve manually, completely eliminating lateral gaps and tilting of the specimen 13. The entire process is seamless, and should be completed within 1-2 seconds from the insertion of the specimen to the unzipping.

[0035] S103. Data Reading and Reset (corresponding to step S3 in claim 1): After the extrusion plate 8 completes the extrusion action and the position of the specimen 13 is completely fixed, the pointer of the dial indicator 1 will swing slightly and then stabilize. At this time, the operator quickly and accurately reads the reading of the dial indicator 1, which is the change in the current length of the specimen 13 from the initial length, and records it. The measurement of a single specimen is completed.

[0036] The reference baffle 5 provides a stable, immovable measurement reference surface. The specimen 13 is pressed tightly against it by the compression plate 8, ensuring the uniformity of the measurement reference. The upper measuring plate 4 is coaxially mounted with the dial indicator 1, ensuring the accuracy of displacement transmission.

[0037] S104. Device Reset: After recording the data, pull back the compression plate 8 with your right hand and re-fix it to the side plate 9 with the zipper 12, so that the spring 10 is compressed and stored, preparing for the next measurement. Take out the measured specimen 13.

[0038] The core of time control: From the start of timing when specimen 13 leaves the alkaline solution in step S101 to the end of timing when the dial gauge reading is completed in step S103, the total time taken for the entire process from S101 to S103, i.e., the time "from solution to reading," is strictly controlled within 3 to 5 seconds. This is far superior to the standard requirement of 15 ± 5 seconds, minimizing non-reactive length changes in the specimen caused by temperature drop and surface moisture evaporation, and ensuring that the measurement results truly reflect the expansion amount of the alkali-aggregate reaction.

[0039] Repeated measurements: By repeating steps S101 to S104 above, continuous and rapid measurements of a group of multiple specimens can be completed. Due to the fast device reset and standardized operating procedures, single-person operation is extremely efficient.

[0040] This invention provides a method for measuring the length of alkali-reactive specimens in deep collaboration with a dedicated measuring device. By combining standardized operating procedures with strict time control and linking them with the mechanical characteristics of the device (elastic rapid alignment, stable reference), it successfully solves the problems of accuracy, speed, and consistency in the measurement of alkali-reactive specimens. Those skilled in the art, after understanding the core concept of this invention, can make various improvements and modifications without departing from the spirit of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.

[0041] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for measuring the length of an alkali-reactive specimen, characterized in that, Includes the following steps: S1. Specimen preparation: Take out the specimen that has been cured in constant temperature alkaline solution and clean its surface and the probes at both ends; S2. Specimen loading and alignment: Place the specimen between the upper and lower reference surfaces within the measuring frame; release a pre-fixed, elastically resettable lateral compression mechanism, allowing the mechanism to move under elastic force, pressing one side of the specimen against a fixed reference baffle and ensuring close contact. S3. Data reading: Make the probe of a measuring instrument contact the upper end of the specimen and read the specimen length change value displayed by the measuring instrument; The total operation time from the moment the specimen leaves the constant-temperature alkaline solution in step S1 to the completion of the reading in step S3 is controlled within 15 ± 5 seconds.

2. The method for measuring the length of an alkali-active specimen according to claim 1, characterized in that, The total operation time is 3 to 5 seconds.

3. The method for measuring the length of an alkali-active specimen according to claim 1, characterized in that, In step S1, the cleaning is completed by wiping with an absorbent material.

4. The method for measuring the length of an alkali-active specimen according to claim 1, characterized in that, Step S2 specifically includes: With one hand, lift the measuring rod of the measuring instrument to raise the upper reference surface, and with the other hand, place the specimen into the measuring frame and position it between the upper and lower reference surfaces; then, release the pre-fixed lateral compression mechanism.

5. The method for measuring the length of an alkali-active specimen according to claim 4, characterized in that, The lateral compression mechanism is temporarily fixed by a locking element, and the release action is to unlock the locking element.

6. The method for measuring the length of an alkali-active specimen according to claim 5, characterized in that, The locking element is a zipper (12), the lateral extrusion mechanism is an extrusion plate (8), and the reference baffle is a reference baffle (5).

7. The method for measuring the length of an alkali-active specimen according to claim 6, characterized in that, The measuring instrument is a dial indicator (1).

8. The method for measuring the length of an alkali-reactive specimen according to any one of claims 1 to 7, characterized in that, The method is used to measure the length change rate of concrete or mortar specimens in alkali-aggregate reaction experiments; in step S1, the constant temperature alkali solution is a 1 mol / L NaOH solution, and the curing temperature is 80±2℃.

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