CN202041529U - A detection device for early self-shrinkage of cement mortar - Google Patents

Abstract

The utility model belongs to the technical field of construction material detection, in particular to a detection device for early autogenous shrinkage of cement mortar, which comprises a dropper, a flask stopper and a conical flask, wherein the flask stopper is plugged into the mouth of the conical flask; the flask stopper is provided with a circular hole; the dropper is inserted into the position of the circular hole; the diameter of the circular hole is equal to the external diameter of the dropper; and the dropper is provided with scales. A whole is formed by the dropper with the scales and the conical flask which is provided with the flask stopper and can be well sealed. The dropper with the scales and the flask stopper of the conical flask are tightly connected, and the dropper with the scales and the conical flask form a seal system. By using the detection device for the autogenous shrinkage, the autogenous shrinkage generated on the cement mortar at an early stage can be relatively accurately measured. The detection device for the early autogenous shrinkage of the cement mortar can also be used for determining the early autogenous shrinkage of the cement mortar and is suitable for actual production and scientific research.

Description

A detection device for early self-shrinkage of cement mortar

technical field

The utility model relates to a detection device for early self-shrinkage of cement mortar, which is suitable for testing the early self-shrinkage of cement mortar caused by continuous hydration of cement and internal self-drying.

Background technique

With the vigorous development of the national economy and the continuous growth of the construction industry, cement mortar is more and more widely used in the field of construction technology. The application of cement mortar in practice has brought many obstacles. Self-shrinkage refers to the fact that under the condition of no dehydration to the outside, the internal cement hydration continues, and the free water in the capillary pores is insufficient, so that the internal relative humidity of the cement decreases spontaneously, causing the internal capillary tension to increase and form internal stress. The resulting slurry shrinks and deforms. Autogenous shrinkage mainly occurs in the early stage of cement setting and hardening. At this time, cement hydration continues, and autogenous shrinkage causes the volume of the paste to decrease, but the cement paste structure has a certain strength, which makes the internal stress of the cement paste structure, which eventually leads to structural cracking. . Especially since the high-efficiency water reducer has been widely used in the construction industry, the water-binder ratio has dropped significantly, and the cracking problem caused by autogenous shrinkage has become more and more serious.

The mortar shrinkage measurement device in the national standard is only suitable for detecting the shrinkage deformation of the specimen after hardening, and cannot measure the self-shrinkage deformation of the early plastic stage of the mortar. The working principles of the existing experimental devices for measuring the self-shrinkage of mortar in the early plastic stage can be roughly divided into two types: the principle of volume method and the principle of length and height method: the volume method directly measures the external volume of the slurry, and the change of the external volume is used to measure the mortar. The self-shrinkage size of the body; the length and height method calculates the size of the self-shrinkage change by converting the change in the volume of the cement paste into a measurement of length or height. The volume method is intuitive and has fewer variables, and the result is more accurate than the length and height method, but the implementation of the method is more difficult; although the length and height method is simple to operate and easy to obtain, but because the volume change is converted into a length or height change, the conversion procedure It is cumbersome, there are too many variables, and the accuracy of the final result will also be reduced.

Contents of the invention

The purpose of the utility model is to solve the detection problem of the early self-shrinkage of the current cement mortar, and provide an accurate, simple and practical detection device for the early self-shrinkage of the cement mortar. This experimental device is based on the principle of the volumetric method, which gives full play to the advantages of the volumetric method, which is intuitive and reliable, and at the same time overcomes the difficulties in the experimental operation, making the experimental operation relatively simple.

A detection device for early self-shrinkage of cement mortar proposed by the utility model is composed of a dropper 1, a cork 2 and an Erlenmeyer bottle 3, wherein: the cork 2 is plugged in the mouth of the Erlenmeyer bottle 3, and the cork 2 is provided with There is a round hole, the dropper 1 is inserted into the round hole, and the diameter of the round hole is the same as the outer diameter of the dropper 1, and the dropper 1 is provided with a scale.

In the present utility model, the capacity of the Erlenmeyer flask 3 is 100mL-500mL, the wall thickness is 1mm-5mm, and the material is any one of glass, metal or plastic.

In the present utility model, the maximum measuring range of the dropper 1 is 1 mL or 10 mL.

In the utility model, the detection device is used under the temperature condition of 20°C to 25°C.

Advantage of the utility model and the benefit that produce have:

1) The device is simple, with few spare parts and high stability. Multiple sets of test devices can be used for comparative tests at the same time to improve the utilization efficiency of the test devices and the accuracy of test results.

2) The principle of the volume method is adopted as the basic working principle of the experimental device, and the test results are intuitive and easy to obtain, which greatly reduces the error of the experimental results caused by the introduction of multiple variables in the principle of the length and height method.

3) Using this experimental device to detect early self-shrinkage of mortar or concrete is easy to operate, and does not require high operating skills of the experimenters. To a certain extent, it reduces the adverse effects on the results caused by the mistakes in the operation skills of the experimenters, and has a great impact on improving the results. Precision is beneficial.

4) The data obtained from the test has high precision, the error is within the allowable range, the repeatability of repeated tests is good, and the reliability is high.

5) A device for detecting early self-shrinkage of cement mortar is provided, which solves the problem that there is no early self-shrinkage detection device for cement mortar in the industry for a long time.

6) The device can also be used to detect early self-shrinkage of cement paste.

Description of drawings

Fig. 1 is the structural representation of the utility model.

Fig. 2 is the data chart of self-shrinkage value of embodiment 1.

Fig. 3 is the data chart of self-shrinkage value of embodiment 2.

Fig. 4 is the data chart of self-shrinkage value of embodiment 3.

Numbers in the figure: 1 is a dropper, 2 is a cork, and 3 is an Erlenmeyer flask.

Detailed ways

Further illustrate the utility model below by embodiment.

Example 1:

The device is composed of a graduated dropper 1, a bottle stopper 2 and a conical flask 3, and the cork 2 and the well-sealed conical flask 3 form a whole. A graduated dropper 1 forms a tight connection with the bottle stopper 2 of the Erlenmeyer flask, and forms a sealed system with the Erlenmeyer flask 3 . Firstly, clean the device, dry it and check the tightness, and soak the inside of the device with oil before use. Mix the cement mortar according to the mixing ratio in Table 1, weigh 100g of the prepared cement mortar, put it into a conical flask with a capacity of 100mL, a wall thickness of 1mm, and glass material, and fill it up with oil to ensure that there are no air bubbles in the bottle. After corking the cork, fill up the oil level of the graduated dropper with a maximum volume of 1mL to the 0 mark. Read the reading of the scale tube at this time and record the time, and place it at a temperature of 20°C to 25°C for curing. Starting from 0.5 hours after mixing, read the readings in the scale tube every 0.5 hours and record the readings and time. Continue to record and observe for 24 hours and calculate the shrinkage value. The data is shown in Figure 2.

Table 1 Example 1 cement mortar mix ratio

serial number Cement/g Sand/g water/g Fly ash/%* 1 600 600 180 0 2 540 600 180 10 3 510 600 180 15

*% of mass of cementitious material

Example 2

The test method is consistent with that of Example 1, the difference from Example 1 is that the mixing ratio of cement mortar is different, the fly ash is replaced with silica fume, and a water reducer is added. For example Table 2, the quality of the cement mortar tested in this example is 250g, and this device with a capacity of 200mL and a wall thickness of 5mm is used, and the sample is cured at a temperature of 20°C to 25°C. The test data is shown in Figure 3.

Table 2 Example 2 cement mortar mix ratio

serial number Cement/g Sand/g water/g Water reducer/%* Silica fume/%* 1 600 600 180 0 0 2 540 600 180 0 10 3 510 600 150 0.5 15

*% of mass of cementitious material

Example 3

The difference from Example 1 is that the mix ratio of cement mortar is different. By trying to prepare more mortar with low water-cement ratio, the influence of different water-cement ratios on the early self-shrinkage of cement mortar is studied. Cooperate with such as Figure 3. In this example, the quality of the cement mortar detected is 500g, and the device with a capacity of 500mL and a wall thickness of 3mm is cast iron. The maximum measuring range of the graduated dropper is 10mL, and the sample is placed at a temperature of 20°C to 25°C. maintenance. The test data is shown in Figure 4.

Table 3 Embodiment 3 mix ratio

serial number Cement/g Sand/g water/g Water reducer/%* 1 600 600 180 0 2 600 600 150 0.5 3 600 600 120 0.8

*% of mass of cementitious material

Claims (3)

1. A detection device for early self-shrinkage of cement mortar, characterized in that it is made up of dropper (1), cork (2) and conical flask (3), and cork (2) is plugged in conical flask (3) Bottle mouth, bottle stopper (2) is provided with round hole, and dropper (1) inserts this round hole position, and the diameter of round hole is identical with the outer diameter of dropper (1), and dropper (1) is provided with scale. 2. The detection device for early self-shrinkage of cement mortar according to claim 1, characterized in that the capacity of the Erlenmeyer flask (3) is 100mL～500mL, the wall thickness is 1mm～5mm, and the material is glass, metal or plastic any of these. 3. The detection device for early self-shrinkage of cement mortar according to claim 1, characterized in that the maximum measuring range of the dropper (1) is any one of 1mL or 10mL.

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