CN205333631U - Cement mortar dry shrinkage test jig - Google Patents

Abstract

The utility model provides a cement mortar dry shrinkage test jig belongs to civil engineering field, and its structure includes roof and bottom plate, and roof and bottom plate average level set up, are connected with vertical support between roof and the bottom plate the roof on be equipped with at least one jack of placing the amesdial be equipped with the test piece groove of placing the test piece on the upper surface of bottom plate, jack and test piece groove correspond from top to bottom and coaxial setting one by one. During the use, pouring earlier the test piece, then carrying out the drawing of patterns behind the standard curing with the test piece, on test piece after the drawing of patterns carried out installing after the full water curing test jig, dry environment maintenance was put into to the test jig that will have test piece and amesdial to the air shrinkage rate of test piece is reach through the amesdial measurement. The utility model discloses the operating procedure is simple, and need not to make a round trip to get to put the test piece, has reduced the possibility of the experimental error of sum of errors.

Description

A kind of cement mortar dry shrinkage testing jig

Technical field

This utility model relates to technical field of civil engineering, specifically a kind of cement mortar dry shrinkage testing jig。

Background technology

Since concrete is born, owing to the performance of its brilliance makes it obtain rapid development, concrete is most widely used, the most successful construction material now。Along with society is to modernization development, high-rise building, big depth underground structures, overlength bridge, off-shore airport, even the heavy construction such as marine city gets more and more, and the performance of cement and concrete is had higher requirement: have good workability, intensity is higher, the heat of hydration is lower, volume is more stable, corrosion-resistant and durability is better。And the encountered environment of concrete structure increasingly worsens, containing the air of various harmful components, rainwater and subsoil water and other corrosive mediums etc., the corrosiveness of cement-based material is more and more heavier。

Meanwhile, cement-based material itself exists clearly disadvantageous, for instance it shrinks。When cement-based material is in free state, its contraction does not have any adverse effect, but the concrete structure in reality is in different restrained conditions owing to being subject to basis, reinforcing bar or pining down of adjacent part, therefore the contraction of cement-based material easily produces tension therein, and then causes problem of Cracking。The cement-based material of cracking is more susceptible to the erosion of environment, and under the effect of environment, its performance declines further, thus reducing its service life, possibly even causing seepage for water-retaining structure thing, causing potential safety hazard。

In the last few years, the shrinkage cracking problem about the volume stability of high performance concrete particularly high performance concrete became the topic that engineering circles, academia or even the public pay special attention to。Therefore becoming a highly important job for the detection of concrete volume stability, and concrete dry shrinkage occupies a critically important part in concrete total contraction, therefore, the mensuration tool for dry shrinkage is of great significance。

At present, the test method that cement mortar dry shrinkage adopts is to adopt two ends equipped with the die trial of the 25mm × 25mm × 280mm of spherical ailhead, three test specimens of molding。First carry out maintenance in water after molding, then will measure test specimen initial length, and then test specimen be put in dry care environments, carry out maintenance, measure its length in certain age and then calculate its shrinkage factor。The measurement instrument that this method of testing adopts is cement mortar dry shrinkage instrument, and this instrument single can only measure a test specimen, and all needs by length necessarily to demarcate pole pair instrument before measuring every time and demarcate。Test specimen is taken out from care environments and carries out, again test specimen is put back to after being measured and care environments is dried maintenance。The certainty of measurement of dry shrinkage often reaches micron level, and this measuring method has the disadvantage that: all need to demarcate before measuring, complex operation every time, and owing to calibration process itself exists error, thus increase measurement error；Test specimen pick and place the change being likely to make test specimen cause piece lengths owing to colliding with back and forth, thus causing error；Being taken out from care environments by test specimen, due to variation of ambient temperature, the piece lengths that can temperature be caused change is incorporated in measurement, interferes, and the change of ambient humidity also causes measurement error；Owing to anthropic factor is more in measurement process, manual operation the error caused is bigger。

Utility model content

For the problems referred to above, the purpose of this utility model is in that to provide a kind of cement mortar dry shrinkage testing jig, and this testing jig measures accurate, simple to operate, reliable results。

The technical scheme in the invention for solving the technical problem is: a kind of cement mortar dry shrinkage testing jig, including top board and base plate, top board and base plate are all horizontally disposed with, vertical support it is connected between top board and base plate, described top board is provided with at least one jack placing amesdial, the upper surface of described base plate is provided with the test specimen groove placing test specimen, jack and test specimen groove one_to_one corresponding and is coaxially disposed。

For increasing the stability of testing jig, improving the accuracy measured, further technical scheme is: the dead in line of described top board, base plate and support。

For ease of amesdial is fixed, further technical scheme is: the side of described top board is provided with amesdial fixing hole, amesdial fixing hole is the screw being connected with jack, the axis of amesdial fixing hole and the axis of jack intersect vertically, and the distance on the upper and lower surface of the axial line distance top board of amesdial fixing hole is equal。

For ease of test specimen is fixed, further technical scheme is: the side of described base plate is provided with test specimen fixing hole, test specimen fixing hole is the screw being connected with test specimen groove, the axis of the axis of test specimen fixing hole and test specimen groove intersects vertically, and the distance on the upper and lower surface of the axial line distance test specimen groove of test specimen fixing hole is equal。

For improving the reliability of measurement result, further technical scheme is: when jack is provided with multiple, and multiple jacks are uniformly distributed around the axis of support。

Further technical scheme is: described support is prism or cylinder。Prism or cylinder processing are simple, save material and space。

In order to the test specimen with specification matches, further technical scheme is: the cross section of described test specimen groove is square。

The beneficial effects of the utility model are:

1, test specimen and amesdial are installed the measurement that can carry out cement mortar test specimen dry shrinkage on the tester rack, it is to avoid the staking-out work that cement mortar dry shrinkage is loaded down with trivial details before measuring, without demarcating in measurement process, decrease error；

2, in measurement process, test specimen is installed on the tester rack all the time, it is not necessary to pick and place test specimen back and forth, decreases the possibility causing test specimen to damage；

3, in whole measurement process, it is not necessary to by dry for test specimen removal care environments, decrease the error owing to environmental change causes；

4, measurement amesdial and test specimen position are all fixing, decrease the anthropic factor impact in measurement process, decrease error and the probability of test error。

Accompanying drawing explanation

Fig. 1 is the structural representation of this utility model embodiment。

In figure: 1 top board, 2 jacks, 3 amesdial fixing holes, 4 supports, 5 base plates, 6 test specimen grooves, 7 test specimen fixing holes。

Detailed description of the invention

Below in conjunction with Figure of description and specific embodiment, the utility model will be further described:

As it is shown in figure 1, a kind of cement mortar dry shrinkage testing jig, including top board 1 and base plate 5, top board 1 and base plate 5 are all horizontally disposed with, and are connected to vertical support 4, top board 1 and base plate 5 all cylindrical between top board 1 and base plate 5, support 4 is prism-shaped, the dead in line of top board 1, base plate 5 and support 4。

Top board 1 is provided with the jack 2 of three placement amesdials, jack 2 extends vertically through described top board 1, the aperture of jack 2 is identical with the diameter of the fixing bar of the amesdial adopted, the line in the center of circle of the center of circle of jack 2 and top board 1 is mutually 120 ° of angles, and the distance in the center of circle of the center of circle distance top board 1 of three jacks 2 is equal。Be provided with amesdial fixing hole 3 in the side of top board 1, amesdial fixing hole 3 is the screw being connected with jack 2, and the axis of the axis of amesdial fixing hole 3 and jack 2 intersects vertically, and the distance on the upper and lower surface of the axial line distance top board 1 of amesdial fixing hole 3 is equal。Amesdial fixing hole 2 is used for installing amesdial fixed screw, can be fixedly secured in jack 2 by amesdial by tightening amesdial fixed screw。

Being provided with the test specimen groove 6 placing test specimen, jack 2 and test specimen groove 6 one_to_one corresponding on the upper surface of base plate 5 and be coaxially disposed, test specimen groove 6 is the groove that cross section is square, and the length and width of test specimen groove 6 is 25mm, and the degree of depth of test specimen groove 6 is 10mm～20mm。According to national regulation, the standard size of test specimen is 25mm × 25mm × 280mm, and the cross sectional dimensions of test specimen groove 6 and the size of test specimen adapt, and the degree of depth of test specimen groove 6 is too little is not easy fixing test specimen, and the degree of depth too conference reduces the effective length of test specimen, thus increasing error。

The side of base plate 5 is provided with test specimen fixing hole 7, and test specimen fixing hole 7 is the screw being connected with test specimen groove 6, and the axis of the axis of test specimen fixing hole 7 and test specimen groove 6 intersects vertically, and the distance on the upper and lower surface of the axial line distance test specimen groove 6 of test specimen fixing hole 7 is equal。Test specimen fixing hole 7 is used for installing test specimen fixed screw, can be fixedly secured in test specimen groove 6 by test specimen by tightening test specimen fixed screw。

The length of described support 4 is more than the effective length of cement mortar drying shrinkage test specimen, described effective length refers to after described test specimen groove 6 inserted by test specimen, exceed the piece lengths of described test specimen groove 6, its concrete length is determined according to structure and the range thereof of amesdial, it is therefore an objective to the drying shrinkage of cement mortar drying shrinkage test specimen is changed within the range of amesdial。

The method of testing of the cement mortar dry shrinkage of the present embodiment, comprises the following steps:

Step (1): according to design proportioning preparation cement mortar compound, and be cast in the three joint-trial moulds that sample dimensions is 25mm × 25mm × 280mm；

Step (2): test specimen is 20 DEG C ± 2 DEG C in temperature after having built, relative humidity carries out the demoulding more than after maintenance 24h ± 2h in the environment of 95% (h is hour, hour)；

Step (3): obtain after the demoulding one group of three test specimen is put in the water that temperature is 20 DEG C ± 2 DEG C and carry out full water curing；

Step (4): test specimen in water maintenance 2d (d is day, my god) after, test specimen is taken out from water, dry surface of test piece water and rapidly three test specimens inserted in test specimen groove 6, test specimen is made to be perpendicular to base plate 5 plane, and screw the screw in test specimen fixing hole 7, make test specimen be fixed well；Then rapidly three amesdials are inserted in three jacks 2 respectively, the fixing bar making amesdial is perpendicular to top board 1 plane, and amesdial measuring staff is withstood on drying shrinkage test specimen end face, regulate the height of amesdial, the drying shrinkage making test specimen controls within the range of amesdial, then screw the screw in amesdial fixing hole 3, fix amesdial；

Step (5): it is 20 DEG C ± 3 DEG C that the testing jig fixing test specimen and amesdial is put into rapidly temperature, and relative humidity is in the dry environment of 50% ± 4%, then reads rapidly the initial reading of amesdial；

Step (6): the reading of three amesdials the average drying shrinkage of calculation testing piece are read in test specimen maintenance in dry environment after predetermined age, and the average drying shrinkage of test specimen is calculated by following formula:

$S=\frac{(L_0^1-L_i^1)+(L_0^2-L_i^2)+(L_0^3-L_i^3)}{3h}*{10}^{-3}$

In formula: S represents average drying shrinkage；

Represent three amesdial readings of predetermined age test specimen respectively；

I represents the age of test specimen；

₀Represent three amesdial initial readings of test specimen respectively；

H represents the effective length of test specimen, deducts the degree of depth of test specimen groove equal to the length of test specimen。

The quantity of jack 2 and test specimen groove 6 can do flexible adjustment according to specifically used requirement, and the test specimen quantity of once mounting can also experimental concrete condition change flexibly。

When the quantity with group test specimen is one, the average drying shrinkage of test specimen is calculated according to formula (1), and described formula (1) is:

$S=\frac{(L_0^1-L_i^1)}{h}*{10}^{-3}---\left(1\right)$

In formula (1): the average drying shrinkage of S；

The amesdial reading of predetermined age test specimen；

The age of i test specimen；

The amesdial initial reading of test specimen；

The effective length of h test specimen, deducts the degree of depth of test specimen groove equal to the length of test specimen；

When the quantity with group test specimen is multiple, the average drying shrinkage of test specimen is calculated according to formula (2), and described formula (2) is:

$S=\frac{(L_0^1-L_i^1)+(L_0^2-L_i^2)+\mathrm{...}+(L_0^n-L_i^n)}{nh}*{10}^{-3}---\left(2\right)$

In formula (2): the average drying shrinkage of S；

The amesdial reading of predetermined age test specimen；

The amesdial initial reading of test specimen；

The age of i test specimen；

N is with the sum organizing test specimen；

The effective length of h test specimen, deducts the degree of depth of test specimen groove equal to the length of test specimen。

It is the test specimen being once simultaneously attached on testing jig with group test specimen。

In this utility model, the shape of top board 1 and base plate 5 is not limited to the cylinder described in embodiment, it is also possible to be set to square or other polygon, but relative to other shapes, cylindrical top board 1 and base plate 5 compare saving space, save material。

In this utility model, the shape of support 4 is not limited to the prism described in embodiment, and support 4 provides installing space for roof supporting 1 and for test specimen, and support 4 also can adopt other shapes such as cylinder, framework shape。

The foregoing is only preferred embodiment of the present utility model; it it is not whole embodiment of the present utility model; not in order to limit this utility model; all within spirit of the present utility model and principle; any amendment of being made, equivalent replacement, improvement etc., should be included within protection domain of the present utility model。

Except technical characteristic described in description, all the other technical characteristics are those skilled in the art's known technology, and in order to highlight innovative characteristics of the present utility model, above-mentioned technical characteristic does not repeat them here。

Claims (7)

1. a cement mortar dry shrinkage testing jig, it is characterized in that, including top board and base plate, top board and base plate are all horizontally disposed with, vertical support it is connected between top board and base plate, described top board is provided with at least one jack placing amesdial, the upper surface of described base plate is provided with the test specimen groove placing test specimen, jack and test specimen groove one_to_one corresponding and is coaxially disposed。

2. a kind of cement mortar dry shrinkage testing jig according to claim 1, is characterized in that, the dead in line of described top board, base plate and support。

3. a kind of cement mortar dry shrinkage testing jig according to claim 1, it is characterized in that, the side of described top board is provided with amesdial fixing hole, amesdial fixing hole is the screw being connected with jack, the axis of amesdial fixing hole and the axis of jack intersect vertically, and the distance on the upper and lower surface of the axial line distance top board of amesdial fixing hole is equal。

4. a kind of cement mortar dry shrinkage testing jig according to claim 1, it is characterized in that, the side of described base plate is provided with test specimen fixing hole, test specimen fixing hole is the screw being connected with test specimen groove, the axis of the axis of test specimen fixing hole and test specimen groove intersects vertically, and the distance on the upper and lower surface of the axial line distance test specimen groove of test specimen fixing hole is equal。

5. a kind of cement mortar dry shrinkage testing jig according to claim 1, is characterized in that, when jack is provided with multiple, multiple jacks are uniformly distributed around the axis of support。

6. a kind of cement mortar dry shrinkage testing jig according to claim 1, is characterized in that, described support is prism or cylinder。

7. a kind of cement mortar dry shrinkage testing jig according to claim 1, is characterized in that, the cross section of described test specimen groove is square。