阅读说明：本技术 水泥负温水化的评价方法及装置 (Method and device for evaluating cement negative temperature hydration ) 是由 叶家元 张文生 程华 王敬宇 任俊儒 于 2020-03-12 设计创作，主要内容包括：本发明的主要目的在于提供一种水泥负温水化的评价方法及装置。所述方法包括以下步骤：将测试温度T<Sub>1</Sub>的水泥配制为浆体；获取其温度随测量时间的变化关系；测试环境保持于测试温度下,浆体与环境间的散热常数≤100焦耳/(小时×摄氏度)；由浆体的温度变化计算得到温度极值T<Sub>2</Sub>；若不存在T<Sub>2</Sub>或者(T<Sub>2</Sub>-T<Sub>1</Sub>)<10℃,则判定其不适用于该测试温度对应的负温环境施工。所要解决的技术问题是此方法及装置可以快速直观地获取水泥于负温下水化时浆体的温度变化,准确地评价水泥于该负温下是否发生了水化,以及水泥于该负温下的水化反应的速度和剧烈程度如何,极大地缩短了水泥产品的研发时间,提高了效率,也能定性、定量地评价和预测负温水泥的性能,从而更加适于实用。(The invention mainly aims to provide a method and a device for evaluating cement negative temperature hydration. The method comprises the following steps: will test the temperature T 1 Preparing the cement into slurry, obtaining the change relation of the temperature along with the measuring time, keeping the testing environment at the testing temperature, and calculating the temperature extreme value T according to the temperature change of the slurry, wherein the heat dissipation constant between the slurry and the environment is less than or equal to 100 joules/(hour × DEG C) 2 (ii) a If T is not present 2 Or (T) 2 ‑T 1 )<And if the temperature is 10 ℃, judging that the construction is not suitable for the negative temperature environment construction corresponding to the testing temperature. The method and the device can quickly and intuitively acquire the temperature change of the slurry when the cement is hydrated at the negative temperature, accurately evaluate whether the cement is hydrated at the negative temperature and how fast and violent the hydration reaction of the cement at the negative temperature, greatly shorten the research and development time of cement products, improve the efficiency, and qualitatively and quantitatively evaluate and predict the performance of the negative temperature cement, thereby being more practical.)

1. The method for evaluating the negative temperature hydration of the cement is characterized by comprising the following steps of:

1) preparing cement and auxiliary materials with the test temperature into slurry with the test temperature; wherein, the test temperature T₁≤0℃；

2) Obtaining the change relation of the temperature of the slurry along with the measurement time, wherein the environment temperature in the test time is kept at the test temperature, and the heat dissipation constant between the slurry and the environment is less than or equal to 100 joules/(hour × ℃);

3) calculating a time value t with the first derivative equal to 0 and the second derivative smaller than 0 by taking the measured first derivative and the second derivative of the temperature of the slurry against time;

if the time value t does not exist, the cement is considered to be incapable of hydrating at the testing temperature, and the cement is judged to be not suitable for construction at the testing temperature; alternatively, the first and second electrodes may be,

taking the temperature corresponding to the minimum time in the time value T as T₂Calculating Δ T ═ T₂-T₁In units of; and if the delta T is less than 10 ℃, the cement is considered to be difficult to hydrate at the test temperature, and the cement is judged to be not suitable for construction at the test temperature.

2. The method according to claim 1, wherein when the test temperature is-30 ℃ to-20 ℃, the following condition is satisfied if the measurement result is obtained:

delta T is more than or equal to 45 ℃ and T₁≤40min、t₂Less than or equal to 200 min; alternatively, the first and second electrodes may be,

delta T is more than or equal to 30 ℃ and less than 45 ℃, and T₁≤30min、t₂Less than or equal to 200 min; alternatively, the first and second electrodes may be,

delta T is more than or equal to 10 ℃ and less than 30 ℃, and T₁≤20min、t₂≤100min；

Judging that the cement is suitable for construction in an environment of-30 ℃ to-20 ℃;

wherein, t₁Epitaxial initiation time, t, for temperature variation₂The epitaxial termination time for temperature change.

3. The method according to claim 1, wherein when the test temperature is-20 ℃ to-10 ℃, the following condition is satisfied if the measurement result is obtained:

delta T is more than or equal to 45 ℃ and T₁≤40min、t₂Less than or equal to 200 min; alternatively, the first and second electrodes may be,

delta T is more than or equal to 30 ℃ and less than 45 ℃, and T₁≤30min、t₂Less than or equal to 200 min; alternatively, the first and second electrodes may be,

delta T is more than or equal to 10 ℃ and less than 30 ℃, and T₁≤20min、t₂≤100min；

Judging that the cement is suitable for construction at the temperature of between 20 ℃ below zero and 10 ℃ below zero;

wherein, t₁Epitaxial initiation time, t, for temperature variation₂The epitaxial termination time for temperature change.

4. The method according to claim 1, wherein when the test temperature is-10 ℃ to 0 ℃, the following condition is satisfied if the measurement result is obtained:

delta T is more than or equal to 30 ℃ and T₁≤40min、t₂Less than or equal to 200 min; alternatively, the first and second electrodes may be,

delta T is more than or equal to 10 ℃ and less than 30 ℃, and T₁≤20min、t₂≤200min；

Judging that the cement is suitable for construction at the temperature of-10-0 ℃;

wherein, t₁Epitaxial initiation time, t, for temperature variation₂The epitaxial termination time for temperature change.

5. The utility model provides an evaluation device of cement negative temperature hydration, includes the thermostated bath box, its characterized in that, it includes:

the closed container comprises a cylinder body and a cover body which are detachably connected; the barrel body and the cover body sequentially comprise an inner wall, a heat insulation material layer and an outer wall from inside to outside; the cover body is provided with a sensor interface;

the temperature sensor is detachably connected to the cover body through the sensor interface; the middle upper part of the temperature sensor is provided with threads for mounting a sensor protection shell;

the reaction container is movably arranged in the closed container and is used for containing slurry; the bottom surface of the sealed container is isolated from the bottom surface of the sealed container by adopting a heat insulation material layer, and a gap is arranged between the side wall of the sealed container and the side wall of the sealed container;

and the bracket is arranged in the constant-temperature bath box body and is used for supporting the closed container.

6. The apparatus of claim 5, further comprising a metal clip for securing said temperature sensor to said cover; a rotatable spanner is arranged above the metal clamp, and the metal clamp and the spanner are integrally machined.

7. The apparatus according to claim 5, wherein the closed container is placed in a constant temperature bath at a constant temperature; the distance between the outer wall of the constant temperature bath box body and the side wall, the bottom surface and the liquid level of the constant temperature bath box body is more than or equal to 10 mm.

8. The apparatus of claim 5, wherein the closed container has a heat dissipation constant of 100 joules/(hour × degrees C.).

9. The device of claim 5, wherein the temperature sensor ranges from-35 ℃ to 60 ℃; the constant temperature bath box body is provided with a temperature monitoring device, and the measuring range of the temperature monitoring device is-40-60 ℃.

Technical Field

The invention belongs to the technical field of cement performance measurement, and particularly relates to a method and a device for evaluating cement negative temperature hydration.

Background

Negative temperature construction is more and more common in winter, and along with the polar strategy of China, the development of cement-based cementing materials meeting the negative temperature environment requirements is urgent. Under the condition of negative temperature, whether the hydration reaction of the cement occurs, the speed and the intensity of the hydration reaction and the like are the keys for determining whether the cement is suitable for construction in the negative temperature environment. Therefore, the evaluation and the test of the cement negative temperature hydration performance are extremely important for the preparation and the construction of the cement for the negative temperature environment.

According to the research of the prior art, no method and device specially aiming at the cement hydration performance evaluation under the negative temperature condition are available at present. Therefore, the evaluation of the cement negative temperature hydration performance is still blank at present, and great difficulty is caused to research and development effect evaluation and research and development efficiency improvement of research and development personnel.

Disclosure of Invention

The invention mainly aims to provide a method and a device for evaluating cement negative temperature hydration, aiming at solving the technical problem that the existing method and device are not suitable for evaluating the cement negative temperature hydration performance under a negative temperature environment, and providing the method and the device for evaluating the cement negative temperature hydration, which can quickly and intuitively obtain the temperature change curve of slurry when cement is hydrated under the negative temperature, accurately evaluate whether the cement is hydrated under the negative temperature, and evaluate the speed and the intensity of the hydration reaction of the cement under the negative temperature, greatly shorten the research and development time of cement products, improve the efficiency, qualitatively and quantitatively evaluate and predict the performance of the negative temperature cement, and are more suitable for practical use.

The purpose of the invention and the technical problem to be solved are realized by adopting the following technical scheme. The invention provides an evaluation method of cement negative temperature hydration, which comprises the following steps:

1) preparing cement and auxiliary materials with the test temperature into slurry with the test temperature; wherein, the test temperature T₁≤0℃；

2) Obtaining the change relation of the temperature of the slurry along with the measurement time, wherein the environment temperature in the test time is kept at the test temperature, and the heat dissipation constant between the slurry and the environment is less than or equal to 100 joules/(hour × ℃);

3) calculating a time value t with the first derivative equal to 0 and the second derivative smaller than 0 by taking the measured first derivative and the second derivative of the temperature of the slurry against time;

if the time value t does not exist, the cement is considered to be incapable of hydrating at the testing temperature, and the cement is judged to be not suitable for construction at the testing temperature; alternatively, the first and second electrodes may be,

taking the temperature corresponding to the minimum time in the time value T as T₂Calculating Δ T ═ T₂-T₁In units of; if Δ T<At 10 ℃, the cement is regarded as the cementAnd the cement is difficult to hydrate at the test temperature, and the cement is judged to be not suitable for construction at the test temperature.

The object of the present invention and the technical problems solved thereby can be further achieved by the following technical measures.

Preferably, the method further comprises the step of, when the test temperature is-30 ℃ to-20 ℃, determining that the following conditions are met: delta T is more than or equal to 45 ℃ and T₁≤40min、t₂Less than or equal to 200 min; or delta T is more than or equal to 30 DEG C<At 45 ℃ and t₁≤30min、t₂Less than or equal to 200 min; or delta T is more than or equal to 10 DEG C<At 30 ℃ and t₁≤20min、t₂Less than or equal to 100 min; judging that the cement is suitable for construction in an environment of-30 ℃ to-20 ℃; wherein, t₁Epitaxial initiation time, t, for temperature variation₂The epitaxial termination time for temperature change.

Preferably, the method further comprises the step of, when the test temperature is-20 ℃ to-10 ℃, determining that the following conditions are met: delta T is more than or equal to 45 ℃ and T₁≤40min、t₂Less than or equal to 200 min; or delta T is more than or equal to 30 DEG C<At 45 ℃ and t₁≤30min、t₂Less than or equal to 200 min; or delta T is more than or equal to 10 DEG C<At 30 ℃ and t₁≤20min、t₂Less than or equal to 100 min; judging that the cement is suitable for construction at the temperature of between 20 ℃ below zero and 10 ℃ below zero; wherein, t₁Epitaxial initiation time, t, for temperature variation₂The epitaxial termination time for temperature change.

Preferably, the method further comprises the step of, when the test temperature is-10 ℃ to 0 ℃, if the measurement result meets the following condition: delta T is more than or equal to 30 ℃ and T₁≤40min、t₂Less than or equal to 200 min; or delta T is more than or equal to 10 DEG C<At 30 ℃ and t₁≤20min、t₂Less than or equal to 200 min; judging that the cement is suitable for construction at the temperature of-10-0 ℃; wherein, t₁Epitaxial initiation time, t, for temperature variation₂The epitaxial termination time for temperature change.

The object of the present invention and the technical problem to be solved are also achieved by the following technical means. The invention provides an evaluation device for cement negative temperature hydration, which comprises a constant temperature bath box body, and the evaluation device comprises:

the closed container comprises a cylinder body and a cover body which are detachably connected; the barrel body and the cover body sequentially comprise an inner wall, a heat insulation material layer and an outer wall from inside to outside; the cover body is provided with a sensor interface;

the temperature sensor is detachably connected to the cover body through the sensor interface; the middle upper part of the temperature sensor is provided with threads for mounting a sensor protection shell;

the reaction container is movably arranged in the closed container and is used for containing slurry; the bottom surface of the sealed container is isolated from the bottom surface of the sealed container by adopting a heat insulation material layer, and a gap is arranged between the side wall of the sealed container and the side wall of the sealed container;

and the bracket is arranged in the constant-temperature bath box body and is used for supporting the closed container.

The object of the present invention and the technical problems solved thereby can be further achieved by the following technical measures.

Preferably, the device further comprises a metal clip for fixing the temperature sensor to the cover; a rotatable spanner is arranged above the metal clamp, and the metal clamp and the spanner are integrally machined.

Preferably, the apparatus is characterized in that the closed container is placed in a constant temperature bath at a constant temperature; the distance between the outer wall of the constant temperature bath box body and the side wall, the bottom surface and the liquid level of the constant temperature bath box body is more than or equal to 10 mm.

Preferably, in the device, the heat dissipation constant of the closed container is less than or equal to 100 joules/(hour × ℃).

Preferably, in the device, the range of the temperature sensor is-35 to 60 ℃; the constant temperature bath box body is provided with a temperature monitoring device, and the measuring range of the temperature monitoring device is-40-60 ℃.

By means of the technical scheme, the method and the device for evaluating the cement negative temperature hydration, provided by the invention, have the advantages that:

1. according to the method and the device for evaluating the cement negative temperature hydration, the polyurethane layer and the air layer are adopted to isolate the cement paste from the external environment through the heat-insulating closed container, so that the method and the device have a good heat-insulating effect, can prevent the dissipation of heat released during the hydration of the cement, and are convenient to obtain a temperature change curve capable of accurately reflecting the hydration process;

2. according to the method and the device for evaluating the cement negative temperature hydration, the barrel body and the cover body of the closed container are connected in a threaded rotating mode, so that the method and the device have good sealing performance, are convenient and practical, and are simple to operate;

3. according to the method and the device for evaluating the cement negative temperature hydration, the metal cover body is designed in a U shape and is filled with the polyurethane layer, and the temperature sensor can be inserted into the sensor interface of the temperature sensor to enter the inside of the slurry body, so that the heat preservation performance of the whole device is further ensured, and the relative accuracy of an evaluation result is ensured;

4. according to the method and the device for evaluating the cement negative temperature hydration, the temperature sensor is fixed by the metal clamp with the threads, so that the problem that the sealing performance of the temperature sensor is influenced by the expansion of the diameter of an upper interface of a cover body due to the fact that the temperature sensor is inserted and taken for many times is solved; moreover, only the corresponding metal clip needs to be replaced when the device is disassembled and replaced, so that the service life of the device is prolonged, and the maintenance difficulty and cost are greatly reduced;

5. according to the method and the device for evaluating the negative temperature hydration of the cement, the screw thread is arranged on the middle upper part of the temperature sensor and the plastic protective shell is arranged, so that the temperature sensor and the plastic protective shell can be effectively separated, the matched plastic protective shell is installed again during the secondary test, a new sensor does not need to be replaced every time, the use times of the temperature sensor are greatly prolonged, and the cost is obviously reduced; moreover, the temperature sensor can be effectively immersed in the cement slurry, so that the accuracy of a tested temperature curve is ensured;

6. the method and the device for evaluating the cement negative temperature hydration summarize the standard of the cement negative temperature hydration reaction evaluation through a large amount of laboratory data, utilize the data for evaluating the cement negative temperature hydration performance to be identical with the actual data of engineering construction in the extremely cold region, not only can effectively guide the research and development of cement products, but also can provide a basis for the performance evaluation of products suitable for the extremely cold region.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings.

Drawings

FIG. 1 is a graph showing the change in hydration temperature of muddy water in an environment of-10 ℃;

FIG. 2 is a graph showing the change in hydration temperature of muddy water in an environment of-20 ℃;

FIG. 3 is a graph showing the variation of cement hydration temperature in an environment of-30 ℃;

FIG. 4 is a schematic structural view of a cement slurry reaction system in the apparatus proposed by the present invention;

FIG. 5 is a schematic structural diagram of a negative temperature hydration evaluation device for cement provided by the invention.

Detailed Description

To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the following detailed description will be given to the specific implementation, structure, characteristics and effects of the method and apparatus for evaluating cement hydration at negative temperature according to the present invention with reference to the accompanying drawings and preferred embodiments.

The invention provides an evaluation method of cement negative temperature hydration, which comprises the following steps: 1) preparing cement and auxiliary materials with the test temperature into slurry with the test temperature; wherein, the test temperature T₁The temperature of the slurry is less than or equal to 0 ℃, 2) the change relation of the temperature of the slurry along with the measurement time is obtained, wherein the environment temperature in the test time is kept at the test temperature, the heat dissipation constant between the slurry and the environment is less than or equal to 100 joules/(hour × ℃), 3) the first derivative and the second derivative of the measured temperature of the slurry to the time are calculated, the time value T with the first derivative equal to 0 and the second derivative smaller than 0 is calculated, if the time value T does not exist, the cement is regarded as being not hydratable at the test temperature, the cement is judged to be not suitable for construction at the test temperature, or the temperature corresponding to the minimum moment in the time value T is taken as T₂Calculating Δ T ═ T₂-T₁Unit ofIs that; if Δ T<And if the temperature is 10 ℃, the cement is considered to be difficult to hydrate at the testing temperature, and the cement is judged to be not suitable for construction at the testing temperature.

When cement evaluation is carried out, firstly, the cement to be evaluated and auxiliary materials are subjected to a first constant temperature at a test temperature, prepared into slurry at the test temperature, and the slurry is placed in a heat-insulating closed container; and (3) placing the closed container at the test temperature for second constant temperature to obtain the temperature of the slurry within the measurement time.

The cement hydration can be judged according to the maximum value of the temperature rise of the cement under the evaluated negative temperature condition, because the temperature of the slurry has obvious temperature rise within any time, for example, 10 ℃, the hydration reaction can be judged, the slurry can emit heat as long as the cement hydration reaction occurs, the slurry can be heated as long as the heat is emitted, and the temperature of the slurry can be correspondingly increased, the specific heat capacity of the water is 4.2 kilojoules/(kilogram × ℃), and the specific heat capacity of the slurry is larger than that of the water, therefore, the cement hydration reaction can be sufficiently proved when the temperature rise is more than or equal to 10 ℃.

Preferably, the testing temperature is-30 ℃ to 0 ℃; the method is suitable for evaluating the hydration performance of the cement-based cementing material constructed in an extremely cold area at the temperature of-30-0 ℃.

The cement can be evaluated by the evaluation method only when the cement does not freeze under the evaluation negative temperature environment.

According to the test method disclosed by the invention, through a large number of test evaluations, technical support and guidance can be provided for guiding the selection of cement in the construction process of extremely cold regions, and the specific selection can be referred to as shown in the following table 1.

TABLE 1 Cement recommendation schemes applicable in different negative temperature environments

In Table 1 above, t₁Is the starting time of said temperature change. It should be noted that the start time here is not a start time in absolute terms, but is a time corresponding to the intersection of the tangents of the two temperature profiles in which the curve occurs, and the value of the start time is greater than the absolute start time (the time at which the temperature rise starts relative to the test temperature), so t₁Also known as extrapolated start time; in the same way, t₂Is the end time of said temperature change, also called extrapolated end time.