CN201247042Y - Device for measuring early age period linear deformation of cement based material - Google Patents

Abstract

The utility model discloses a measuring device for the linear deformation of cement-based materials at an early age. The measuring device comprises: a measuring chamber with an upper end opening formed by a bottom plate, a side plate and an outer end plate; The template is provided with inner end plates at both ends of the template, and a separation groove is opened in the middle of the template to divide the template into two sliding templates. Compared with the prior art, the measuring device of the utility model is equipped with a sliding template on the bottom plate, and the template is divided into two pieces by the separation groove. The template measures its displacement without waiting for the cement-based material to harden, thereby accurately reflecting the linear deformation characteristics of the cement-based material at an early age. The bottom plate and the template are provided with chute respectively, and balls are arranged in the chute, so that the sliding friction is changed into rolling friction, the friction force is greatly reduced, and the measurement accuracy is improved.

Description

Measuring device for early-age linear deformation of cement-based materials

technical field

The utility model relates to a measuring device for early-age linear deformation of cement-based materials, which can be used for forming molds for early-age linear deformation of cement-based materials such as cement paste, mortar, concrete, and solid materials such as aggregates under unconstrained conditions. and take measurements. Under different heating systems and curing systems, it can measure the thermal expansion coefficient, self-shrinkage and drying shrinkage of cement-based materials in the early stage.

Background technique

In the field of civil engineering, early age cracking prediction of concrete structures is very important. At the early age of the concrete structure, the thermodynamic properties of the concrete material are extremely unstable, and various thermodynamic properties of the early-age concrete directly determine the cracking evaluation of the early-age concrete. Accurately measure various thermodynamic properties of the early-age concrete The law of development is very necessary. The coefficient of thermal expansion, autogenous shrinkage and drying shrinkage are the main factors affecting the cracking of early-age concrete. Therefore, the design of the measurement mold must not only be suitable for the characteristics of the extremely poor anti-disturbance ability of early-age concrete, but also eliminate the error of the mold during the measurement process as much as possible. .

At present, there are mainly two methods for measuring the early-age deformation of cement-based materials: volumetric method and linear method.

In the volumetric method, liquid is generally used as the medium, and the measurement of the volume change of the cement-based specimen is converted into the measurement of the volume change of the liquid. Chinese Patent No. 200510050171.6 uses the principle that the volume change of concrete causes the change of water level difference in the container to measure the volume deformation of concrete at an early age. This method is rarely used in scientific research and production, mainly because it is difficult to wrap the volume of conventional concrete mixture and the test accuracy of the volume method is not high.

In terms of the linear method, according to the provisions of the "Hydraulic Test Regulations" DL-T5150-2001, the mold for measuring the thermal expansion coefficient and self-shrinkage of cement-based materials is an iron bucket with a diameter of 200 mm and a height of 500 mm. More than 7 days. The "Hydraulic Test Regulations" did not take into account that most of the hydration temperature rise of cement-based materials is completed before the age of 7 days, and the thermal expansion coefficient of concrete after initial setting has more practical significance for predicting cracking of concrete at an early age. "Hydraulic Test Regulations" does not consider the problem of eliminating friction between the test piece and the mold, and the cylindrical test piece is not uniform with the traditional cuboid test piece in my country, the mold is rough, and the test accuracy is low. A new type of mold should be designed.

In recent years, some molds and test methods applied to the measurement of linear deformation of early-age concrete have been disclosed. Chinese Patent No. 200510012299.3 discloses an automatic measurement system for concrete temperature linear deformation, and proposes an automatic method for measuring the linear expansion coefficient of concrete, but its mold is not suitable for the measurement of early-age cement-based materials. Chinese Patent No. 200610038892.X discloses a method and device for testing the early self-deformation of concrete, which can make the initial time of self-shrinkage measurement earlier after pouring, but it is not suitable for early-age concrete because there is no temperature control system Determination of the coefficient of thermal expansion.

The thermal performance of the test platform material is often ignored, but it greatly affects the test measurement results, causing large errors.

Most of the guide rods used for deformation measurement are copper alloy guide rods. The thermal expansion coefficient of copper alloy is between 16.6-17.6×10 ^-6 /℃, which is not suitable for tests with large changes in ambient temperature, and the distance between it and the steel mold It is very inconvenient to install and disassemble.

Therefore, in order to accurately measure the early-age linear deformation of cement-based materials, it is necessary to design a measuring device and method for measuring the early-age linear deformation of cement-based materials, which can not only reduce the test cost of thermal expansion coefficient and various shrinkage, but also benefit cement Unification of linear deformation measurements at early ages of base materials.

Contents of the invention

The technical problem to be solved by the utility model is to provide a measuring device for the linear deformation of the cement-based material at an early age in view of the above-mentioned deficiencies in the prior art. Using this mold, the linear deformation can be carried out after the cement-based material has a little plasticity. Measurement, which can measure the thermal expansion coefficient, self-shrinkage and drying shrinkage of cement-based materials in the early stage.

In order to solve the above-mentioned technical problems, the measuring device of the present utility model comprises: a measuring chamber with an upper end opening formed by a base plate, a side plate and an outer end plate, a sliding template is also arranged on the base plate, and the template Inner end plates are provided at the two ends of the template, and a separation groove is opened in the middle of the template to divide the template into two sliding templates.

A first chute is provided on the lower end surface of the template, a second chute is provided on the upper end surface of the bottom plate, and a ball is provided between the first chute and the second chute, so The sliding formwork described above slides on the bottom plate through the balls arranged in the first slide groove and the second slide groove.

There are three first slide grooves arranged on the sliding formwork, which are arranged in a triangle, and there are six second slide grooves arranged on the bottom plate, which are respectively adapted to the first slide grooves of the slide formwork.

A bump is also arranged on the inner end plate.

The material of the inner end plate is Invar alloy.

Compared with the prior art, the utility model measuring device has the following advantages:

1. Set the template slidingly on the bottom plate, and the template is divided into at least two pieces by the separation groove. When the cement-based material specimen shrinks, its displacement can be measured through the sliding template bonded to the cement-based material, without waiting for the cement The base material hardens, thus accurately reflecting the linear deformation characteristics of cement-based materials at an early age.

2. The shrinkage of cement and materials is very small, and when shrinking, the deformation force generated is also very small. When the friction between the sliding formwork and the bottom plate is large, it cannot well reflect the actual early age of cement-based materials. The characteristics of linear deformation, for this reason, the measuring device of the utility model has chute respectively on the base plate and the template, and balls are arranged in the chute, so that the sliding friction is changed into rolling friction, which greatly reduces the friction force and improves the the measurement accuracy.

3. The chute is arranged in a triangle. On the one hand, it can improve the stability of the formwork sliding on the base plate. On the other hand, it also ensures that the base plate and formwork are relatively parallel, so that when the formwork slides on the base plate, the force is balanced and there will be no The phenomenon of increasing friction such as tilting occurs, further improving the accuracy of measurement.

4. In order to further improve the measurement accuracy, an inner end plate made of Invar alloy is also set in the outer end plate, which effectively reduces the influence of temperature deformation of the inner end plate on the measurement accuracy. At the same time, a convex block to strengthen the bond between the test piece and the inner end plate, which is conducive to the simultaneous expansion and contraction of the test piece and the inner end plate.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of a measuring device for early-age linear deformation of cement-based materials of the present invention.

Fig. 2 is a schematic diagram of the connection structure between the bottom plate and the template of the measuring device of the present invention.

Fig. 3 is a structural schematic diagram of the bottom plate of the measuring device of the present invention.

Fig. 4 is a schematic diagram of the structure of the outer end plate of the measuring device of the present invention

Fig. 5 is a schematic diagram of the structure of the inner end plate of the measuring device of the present invention.

Fig. 6 is a schematic diagram of a device for testing self-shrinkage of cement-based materials according to the present invention.

Fig. 7 is a schematic diagram of a measuring device for testing the second specimen of the coefficient of thermal expansion of cement-based materials according to the present invention.

Fig. 8 is a schematic diagram of typical early autogenous shrinkage test results of concrete, where w/c=0.35, cement dosage is 480kg/m ³ , the abscissa is age (h), and the ordinate is strain (×10 ^-6 ).

Figure 9 is a schematic diagram of the variation of the thermal expansion coefficient with age for the mortar specimen of W:C:S=1:3:5, the abscissa is the age (h), and the ordinate is the thermal expansion coefficient (×10 ^-6 /℃) .

Figure 10 is a schematic diagram of the drying shrinkage of concrete at an early age as a function of age when the maximum particle size of the aggregate is 16 mm and 20 mm, respectively. The abscissa is age (h), and the ordinate is strain (×10 ^-6 ).

Detailed ways

Below in conjunction with accompanying drawing, the utility model is described in detail:

As shown in Figure 1, the measuring device for the linear deformation of cement-based materials in the present invention includes a steel base plate 1, and 6 small elongated grooves are symmetrically opened on the upper surface of the steel base plate 1, and corresponding to the sides are opened around. The plate 2 and the outer end plate 3 are grooved in thickness to install the side plate 2 and the outer end plate 3, see Fig. 2 and Fig. 3 . A formwork 4 is placed on the base plate 1, and the formwork 4 is divided into two sliding formworks 41 by the separation groove 7, and three elongated small grooves corresponding to the base plate 1 are respectively opened on the lower bottom surface of the sliding formwork 41. A steel ball 6 with a diameter slightly smaller than the width of the small groove is placed to ensure that the sliding template 4 slides freely on the base plate 1. The outer sides of the two sliding templates 41 are connected to the inner end plate 5, a space for deformation of the test piece is formed between the inner end plate 5 and the outer end plate, and the total length of the two sliding templates 41 is 2mm smaller than the distance between the two outer end plates 3 , before pouring the test piece, insert the tetrachloropolyethylene insert between the sliding formwork and insert it into the middle groove of the bottom plate 1. When the test piece is slightly plastic, gently pull out the tetrachloropolyethylene insert to ensure that the template Does not affect the free shrinkage of the specimen. Four cube iron blocks 51 are welded on the inner surface of the inner end plate 5 to strengthen the bond between the test piece and the inner end plate 5, which is beneficial to the simultaneous expansion or contraction of the test piece and the inner end plate 5, see FIG. 5 for details. Open four holes symmetrically on both sides of the side plate 2, insert the bolts 8 into the holes on the side plate 2, and tighten the bolts 8. After the template assembly is completed, apply vaseline on the upper surface of the sliding template 4, and cover the vaseline with a double-layer plastic film. If the thermal expansion coefficient and self-shrinkage test are performed, the plastic film is reserved for sealing the test piece. After the test piece is formed, use the quartz glass guide rod 9 to pass through the outer end plate 3 of the hole, as shown in Figure 4, and be directly adsorbed on the outside of the inner end plate 5. When the test piece has a little plasticity, loosen the bolt 8, and remove the side plate 2 and The outer end plate 3 measures the early-age linear deformation of different properties of the specimen under different heating systems and different curing systems.

The measuring method of self-shrinkage, thermal expansion and drying shrinkage of cement-based materials by adopting the measuring device of the utility model is as follows:

Self-shrinkage measurement method of cement-based materials:

A1. Complete the assembly of the measuring device, see Figure 6, place a temperature sensor 13 in the center of the test piece after pouring the test piece, and seal the test piece with a plastic film.

A2. The mold and test piece are placed horizontally on the platform 10, two quartz glass guide rods 9 are adsorbed on the outside of the inner end plate 5, the magnetic table 12 is fixed on both sides of the platform 10, and a high-precision displacement sensor (LVDT) 11 is erected On the quartz glass guide rod 9.

A3. Maintain the test piece at the set temperature, that is, under the condition that the reading of the temperature sensor 13 does not change, at regular intervals, the computer automatically reads the temperature in the test piece and the high-precision displacement sensor (LVDT) 11 . Assume that the readings of the two high-precision sensors (LVDT) 11 for measuring the starting time are respectively Ya0 and Yb0, and the readings after changing with age are respectively Yat and Ybt; The calculation formula of autogenous shrinkage ε _ca,t is as follows:

${\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; at</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; bt</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; at</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; bt</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

Among them, Fig. 8 is a typical concrete early autogenous shrinkage test result graph, where w/c=0.35, and the amount of cement is 480kg/m ³ .

Measurement method of thermal expansion coefficient of cement-based materials:

B1. Complete the assembly of two sets of measuring devices. After pouring the test piece, place a temperature sensor 13 inside the test piece a, place three temperature sensors 13 in the center of the test piece B, and seal the test piece a and the test piece b with a plastic film. . Specimen a is subjected to the self-shrinkage test according to the above-mentioned A, and specimen b is subjected to the thermal expansion coefficient measurement test. The measuring device is shown in Figure 7, and the two tests must be carried out simultaneously.

B2. Place the curing box or temperature-changing equipment 14 horizontally on the support platform 10, then horizontally place the test piece b in the curing box or temperature-changing equipment 14, and finally attach two quartz glass guide rods 9 to the outside of the inner end plate 5, And stretch out the other end of the quartz glass guide rod 9 outside the curing box or the temperature changing equipment 14.

B3. Fix the magnetic watch base 12 on both sides of the platform 10, and set up a high-precision displacement sensor (LVDT) 11 on the quartz glass guide rod 9.

B4. Turn on the curing box or temperature-changing equipment 14, set the temperature-changing system, and use the method of rapid heating and cooling to reduce the influence of self-shrinkage. At regular intervals, the computer automatically reads the temperature inside the test piece and the high-precision displacement sensor (LVDT) 11 .

时自收缩试验的试验结果进行修正，龄期t时单位长度的试件热膨胀系数α_c，t的计算公式如下：B5, two high-precision displacement transducers (LVDT) 11 readings are Ya0 and Yb0 when the test begins; Choose the temperature change section that the measured temperature change rate of three temperature sensors 13 is consistent as the calculation section, and the starting point of the calculation section is three temperatures The average temperature of sensor 13 is respectively X1, and corresponding two high-precision displacement sensors (LVDT) 11 readings are Ya1 and Yb1, and age is t1; The readings of two high-precision displacement sensors (LVDT) 11 are Ya2 and Yb2, the age is t2, and the length L of the test piece is 500mm. Use the corresponding age t as

Correct the test results of self-shrinkage test at age t, and the calculation formula of thermal expansion coefficient α _c,t per unit length at age t is as follows:

${\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; L</span>}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; t</span>}}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>}$

Among them, Figure 9 is a schematic diagram of the change of thermal expansion coefficient with age for mortar with W:C:S ratio of 1:3:5.

Measurement method for drying shrinkage of cement-based materials:

C1. Complete the assembly of two sets of measuring devices. After pouring the test pieces, place a temperature sensor 13 inside the test piece a, place a temperature sensor 13 in the center of the test piece c, and seal the test pieces a and c with a plastic film. Not sealed. Specimen a is subjected to the self-shrinkage test according to the above-mentioned A, and specimen c is subjected to the drying shrinkage measurement test, and the two tests must be carried out simultaneously.

C2. The drying shrinkage test procedure of specimen c is the same as in A.

C3. Maintain the test piece at the set temperature, that is, under the condition that the reading of the temperature sensor 13 does not change, at regular intervals, the computer automatically reads the temperature and the high-precision displacement sensor (LVDT) 11 in the test piece. Let the readings of the two high-precision sensors (LVDT) 11 for measuring the starting time be Ya0 and Yb0 respectively, and the readings after changing with age are respectively Yat and Ybt; let the length L be 500mm. The test results of the autogenous shrinkage test at the corresponding age t are used for correction. The drying shrinkage ε _{cd, t} of the specimen per unit length at the age t is calculated as follows:

${\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; cd</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; at</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; bt</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; at</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; bt</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Y</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; ca</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; t</span>}}$

Among them, Figure 10 is a schematic diagram of the change of concrete drying shrinkage with age when the maximum particle size of the aggregate is 16mm and 20mm respectively.

Claims (4)

1, a kind of measurement mechanism of early age period linear deformation of cement based material, the measurement cavity volume that comprises the upper end open that constitutes by base plate (1), side plate (2) and outer end plate (3), it is characterized in that: on described base plate (1), also be provided with a template (4) of sliding, at the two ends of described template (4) inner end plate (5) is set, offers separating tank (7) at the middle part of described template (4) described template (4) is divided into 2 sleiding forms (41).

2, the measurement mechanism of early age period linear deformation of cement based material according to claim 1, it is characterized in that: be provided with first chute (42) in the lower surface of described template (4), be provided with second chute (11) in the upper surface of described base plate (1), be provided with ball (6) between described first chute (42) and second chute (11), described sleiding form (41) is gone up slip by the ball (6) that is arranged between first chute (42) and second chute (11) at described base plate (1).

3, the measurement mechanism of early age period linear deformation of cement based material according to claim 2, it is characterized in that: first chute (42) that is arranged on the sleiding form (41) is three, and triangularity is arranged, second chute (11) that is arranged on the base plate (1) is 6, and is suitable with first chute (42) of sleiding form (41) respectively.

4, the measurement mechanism of early age period linear deformation of cement based material according to claim 1 and 2 is characterized in that: also be provided with projection (51) on described inner end plate (5).

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