CN100533117C - A dry-wet cycle and fresh water-sea water cycle simulation device - Google Patents

Abstract

The invention relates to a dry-wet cycle and fresh water-sea water cycle simulation device. It consists of a shower head, a water tank, a water tank bracket, a transmission system, a rotating frame and an erosion solution tank. The transmission gear of the transmission system is fixed on the motor shaft, and the controller is connected to the motor; the rotating frame is composed of a ring, a ring bracket and a sample holder. , the ring is fixed to one end of the ring bracket through a shaft, so that the ring can rotate freely on the ring bracket perpendicular to the horizontal plane; the tooth shape of the transmission gear matches the tooth shape on the outer ring of the ring; one side of the ring bracket is equipped with Erosion solution tank, the lower part of the ring is located in the corrosion solution tank; one end of the sample holder is vertically fixed on the outer ring of the ring surface; the shower head is located above the ring, and the water tank is fixed on the water tank bracket below the shower head It rotates between the sink and the shower head. The invention can greatly improve the efficiency of research on the sulfate erosion resistance of cement and concrete, and is closer to actual engineering conditions than traditional methods.

Description

A dry-wet cycle and fresh water-sea water cycle simulation device

technical field

The invention relates to a dry-wet cycle and fresh water-sea water cycle simulation device.

Background technique

At the estuaries of rivers and rivers in our country, many cross-river and sea-crossing projects are planned. Due to the effect of tides, seawater pours into rivers and rivers at high tide, submerging concrete structures below the tidal range, and making concrete withstand chloride salts and various sulfuric acids. Salt erosion; when the tide ebbs, the river and river water begin to erode the concrete, making it subject to fresh water erosion, while the concrete in the tidal range area is exposed to the air. Therefore, the concrete structures of these projects are in the corrosive environment of dry-wet cycle and fresh water-sea water cycle.

Concrete in the marine environment is called marine concrete or marine concrete. Its main damage form is that Cl ions in the sea invade the concrete protective layer and cause corrosion of steel bars. At the same time, various sulfates in seawater corrode concrete for a long time and cause expansion damage. Therefore, the durability of concrete samples is generally studied by immersing them in seawater. For the concrete structures at the mouths of rivers and rivers, due to the aforementioned environmental characteristics different from marine concrete, more serious erosion and damage laws will occur.

The erosion and damage mechanism of sulfate in seawater is that the sulfate solution penetrates into the pores of concrete to produce crystals, and when the crystals accumulate to a certain amount, the resulting crystallization expansion pressure destroys the concrete structure. For concrete that has been immersed in seawater, the sulfate solution first invades the surface pores of the concrete, and crystallizes when the concentration accumulates to a certain value, and the drying process accelerates the crystallization speed. The early crystallization can block the pores and prevent the sulfate solution from further intruding into the concrete, but in the tidal zone, due to the dry-wet cycle, the sulfate crystals crystallized and blocked in the surface pores shrink due to drying, making the blocked pores The channels were re-opened, allowing the sulfate to penetrate deeper into the concrete, eventually causing more severe expansion failure. This is an important reason why concrete in the tidal zone is more severely damaged than concrete completely immersed in seawater. If there is a freshwater-seawater circulation at the same time, the freshwater may dissolve and wash away part of the crystallized sulfate crystals from the surface pores of the structure, making the pores more open and the sulfate more likely to invade deep into the structure. Therefore, there is a certain gap between the corrosion environment of concrete engineering at river and river estuaries and the complete marine corrosion environment. To study the durability of this type of concrete, it is necessary to find targeted research methods in order to find effective protective technical measures.

Regarding the research on the resistance of concrete to seawater erosion, the main methods generally refer to ASTM C1012-02, ASTM C452-02, ASTM C1092-95A, GB/T749-01 "Cement Sulfate Erosion Resistance Test Method" and GB2420-81 "Cement Sulfate Erosion Resistance Rapid Test Method", etc. The common feature of these methods is to continuously immerse the sample in the sulfate solution, and then use various test methods to study the degree of damage of the sample after being soaked for a certain period of time. Up to now, there is no standard method that can simulate the corrosion environment of concrete in the estuary of rivers and rivers, which has both dry-wet cycle and fresh water-sea water cycle.

In summary, the study of an experimental device for simulating concrete subjected to dry-wet cycle and freshwater-seawater cycle erosion has practical significance and theoretical guiding value for the research on the durability of concrete in cross-river and sea-crossing projects located at river and sea estuaries in my country. .

Contents of the invention

The object of the present invention is to provide a dry-wet cycle and fresh water-sea water cycle simulation device.

The dry-wet circulation and freshwater-seawater circulation simulation device proposed by the present invention is composed of a shower head 1, a water tank 3, a water tank support 10, a transmission system, a rotating frame and an erosion solution tank 8, and its structure is shown in Fig. 1 and Fig. 2 . Wherein, transmission system is made up of transmission gear 4, controller 5 and motor 6, and transmission gear 4 is fixed on the axle 13 of motor 6, and controller 5 is connected with motor 6 by wire; Composed with the sample holder 9, the center position of the ring 2 is fixed on one end of the ring bracket 7 through the shaft 12, so that the ring 2 can rotate freely on the ring bracket 7; The tooth shapes on the ring match; one side of the ring support 7 is provided with an erosion solution tank 8, and one side of the ring 2 is located in the erosion solution tank 8; one end of the sample holder 9 is vertically fixed on the outer ring of the ring 2 the other end is suspended; the shower head 1 is located above the ring 2, the water tank 3 is fixed on the water tank support 10, and the sample holder 9 fixed on the top of the ring 2 is located between the shower head 1 and the water tank 3.

In the present invention, the sample 11 is fixed on the sample holder 9 .

In the present invention, the etching solution tank 8 is filled with a sulfate or chloride etching solution.

Working process of the present invention is as follows:

Fix the pre-prepared cement mortar or concrete sample 11 on the rotatable sample holder 9, connect the power supply of the controller 5, adjust the starting interval time of the motor 5 and the rotation time of each motor, so that the ring support 7 Rotate according to the designed cycle (for example, one circle/day can be used), so that the sample 11 fixed on the sample holder 9 rotates with the ring bracket 7, and the sample 7 is immersed in the corrosion solution tank 8, so that the sample 11 11 Complete a cycle in a dry-wet environment and a cycle in a freshwater-seawater environment every day; the shower head 1 is connected to a fresh water source (such as tap water), turn on the shower head 1, and adjust the water volume so that the sprayed sample 11 can keep Uniform wetting, corrosion solutions such as sulfate or chloride salts prepared according to the design are filled in the corrosion solution tank 8 .

Beneficial effects of the present invention:

Adopt the device of the present invention and the method that the sample is directly soaked in the corrosion solution for comparative experiments, in the same sulfate corrosion solution and the same corrosion time, the cement mortar sample obtained by the device of the invention is affected by sulfate The degree of erosion damage is more serious than traditional methods. This aspect shows that the device of the present invention can greatly improve the efficiency of the research on the resistance to sulfate erosion of cement and concrete; And the freshwater-seawater circulation environment, so it is closer to the actual engineering conditions than the traditional method of continuously immersing the sample in the erosion solution.

Description of drawings

Fig. 1 is a schematic diagram of the cross-sectional structure of the present invention.

Fig. 2 is a schematic diagram of the longitudinal section structure of the present invention.

Numbers in the figure: 1 is the shower head, 2 is the ring, 3 is the sink, 4 is the transmission wheel, 5 is the controller, 6 is the motor, 7 is the ring bracket, 8 is the erosion solution tank, 9 is the sample holder, 10 For the sink stand. 11 is a sample, 12 is a motor shaft, and 13 is a shaft on the ring support 7.

Detailed ways

The present invention is further illustrated below by means of embodiments in conjunction with the accompanying drawings.

Embodiment 1: Stainless steel is used to make the ring 2. The diameter of the ring 2 can be determined according to the amount of samples to be tested each time. Generally, a ring 2 with a diameter of 1 meter can be placed at most 60 pieces of 4×4×16cm at a time. Rectangular sample 11. According to the number of test samples 11 that can be placed, use an equal number of stainless steel angle steel or stainless steel flat steel as the sample holder 9, one end of which is welded on the outer ring of the circle perpendicular to the circular surface, and the other end is suspended and fixed on the outer side of the circle of the ring 2. Rubber gear teeth; make the ring support 7, and the ring 2 is installed on the ring support 7 through the shaft, so that the ring 2 can freely rotate on the ring support 7, thereby forming a rotating frame.

Select the motor 6, which is generally two motors, and its power is determined according to the weight of the ring 2 and the sample 11 when it is filled, generally less than 0.5 kilowatts; the power supply capacity of the controller 5 should adapt to the power consumption of the motor 6, and there A variety of specifications are available; the gear 4 is fixed on the shaft of the motor 6, and the gear teeth of the gear 4 correspond to the rubber gear teeth on the outside of the ring 2; the controller 5 and the motor 6 are connected together and connected with the gear together form the transmission system.

Make a tray-type water tank 3, and its size is determined according to the size of the sample. For a rectangular sample of 4×4×16cm, the length is generally 30cm, the width is 20cm, and the height is 6cm; Catch the water dripped from the shower head 1 and do not make the water tank 3 collide with the rotating frame as the criterion; one end of the plastic pipe is connected to the bottom of the water tank 3, and the other end is connected to the sewer or the inlet of the collection container arranged for circulating water.

It is advisable to make a rectangular etching solution tank 8 whose size can completely soak 15%-30% of the sample holders on the rotating frame with its full etching solution.

Install the above devices according to the method shown in Figure 1 and Figure 2, fix the shower head 1 on the upper end of the ring 2, fix the motor 6 beside the ring bracket 7, and make the transmission gear 4 contact with the rubber gear teeth on the outside of the ring 2.

Fix the pre-prepared cement mortar or concrete sample 11 on the rotatable sample holder 9, switch on the power supply of the controller 5, adjust the starting interval time of the motor and the rotation time of each motor, so that the rotating frame can be rotated according to the design. Cycle cycle rotation, generally one revolution per day, even if the test sample completes a cycle in a dry-wet environment and a cycle in a freshwater-seawater environment every day; open the shower head and adjust the water volume so that the sprayed sample 11 can Keep evenly moistened. The shape of the sample 11 is generally a rectangle of 4×4×16 cm, or other shapes such as a cylinder or an irregular shape, and is bound and fixed on the sample holder 9 with a corrosion-resistant rope. In the erosion solution tank 8, the erosion solutions such as vitriol or chloride salt prepared according to the design are filled.

Prepare 3 groups of cement mortar samples of 4 × 4 × 16cm in the same mixing ratio, each group of 3 test blocks, after 28 days of age, get 2 groups of samples and use the experimental device and method of the present invention to compare with the traditional ones. , and another group of samples continued to be cured in the standard curing room as blank samples. In the traditional method, the sample is continuously soaked in the erosion solution of 4% methsulfate+4% sodium sulfate, and the same erosion solution is also housed in the erosion solution tank 8 of the device of the present invention, and the controller 5 is adjusted to make the rotating frame rotate once a day.

After 3 months, the cement mortar samples tested by the two methods were taken out and dried, and the flexural strength of the two groups of samples was tested, and the flexural strength of the blank sample was tested at the same time. Divide the flexural strength of the two experimental samples by the flexural strength of the blank sample to obtain the ratio of the two flexural strengths, which is the basis for judging the sulfate corrosion resistance of the sample. The stronger the sulfate ability or the weaker the erosion damage of sulfate. The experimental and calculation results are shown in Table 1.

Table 1 Adopt the product that the device of the present invention obtains and the product that traditional method obtains about the comparison experiment result of sulfate attack

As can be seen from the experimental results in Table 1, in the same sulfate attack solution and the same erosion time thereof, the sample obtained by the device of the present invention is subjected to the ratio of the flexural strength after sulfate attack to the blank sample flexural strength Obviously less than the ratio of the sample flexural strength obtained by the traditional method of continuously immersing the sample in the erosion solution and the blank sample flexural strength, that is, the cement mortar sample obtained by popularizing the device of the present invention is more damaged by sulfate erosion than the traditional The method is more serious. This aspect shows that the device of the present invention can greatly improve the efficiency of the research on the resistance to sulfate erosion of cement and concrete; And the freshwater-seawater circulation environment is closer to the actual engineering conditions than the traditional method of continuously immersing the sample in the erosion solution.

Claims (3)

1, a kind of drying and watering cycle and fresh water-seawater circulating analog device, form by shower nozzle (1), tank (3), tank support (10), kinematic train, swivel mount and attack solution groove (8), it is characterized in that kinematic train is made up of transmission gear (4), controller (5) and motor (6), transmission gear (4) is fixed on the axle (12) of motor (6), and controller (5) is connected by lead with motor (6); Swivel mount is made up of annulus (2), circle ring rack (7) and specimen mounting (9), and the home position of annulus (2) is fixed in an end of circle ring rack (7) by axle (13), and annulus (2) can be rotated on circle ring rack (7) freely; Profile of tooth on the profile of tooth of transmission gear (4) and annulus (2) outer shroud matches; Circle ring rack (7) one sides are provided with attack solution groove (8), and a side of annulus (2) is positioned at attack solution groove (8); One end vertical fixing of specimen mounting (9) is on the outer shroud of annulus (2) disc, and the other end is unsettled; Shower nozzle (1) is positioned at annulus (2) top, and tank (3) is fixed on the tank support (10) of shower nozzle (1) below, and specimen mounting (9) is along with rotation is passed through between tank (3) and the shower nozzle (1).

2, drying and watering cycle according to claim 1 and fresh water-seawater circulating analog device is characterized in that sample (11) is fixed on the specimen mounting (9).

3, drying and watering cycle according to claim 1 and fresh water-seawater circulating analog device is characterized in that being full of in the attack solution groove (8) sulfate or chloride erosion solution.

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