Device for accelerating generation of carbon-sulfur-silicon-calcium stone in ardealite through electric pulse and using method

Abstract

The invention discloses a device for accelerating generation of carbon-sulfur-silicon-calcium stone in ardealite through electric pulses and a using method. The device mainly comprises an electric pulse generator, a curing box and a power line. The waterproof baffle plate and the porous electrode plate are arranged in the curing box; and the good electrode of the electric pulse generator is connected to the two porous electrode plates through power lines. The device disclosed by the invention is applied to a simulation test for accelerating generation of the carbon-sulfur-silicon-calcium stone in the phosphogypsum-based road stabilizing material, and the test shows that after two groups of samples are respectively soaked for 14 days, the unconfined compressive strength of the samples subjected to continuous pulse for 14 days by pulse voltage is at least 92% of the unconfined compressive strength of the samples cured in a NaOH solution with the same concentration, and the unconfined compressive strength of the samples cured in the NaOH solution with the same concentration is at least 92%. The softening coefficient is 90% of that of a sample cured in a NaOH solution with the same concentration, the purpose of accelerating generation of the carbon-sulfur-silicon-calcium stone in the ardealite-based road stabilizing material can be achieved through the electric pulse, and the device is simple in structure, energy-saving, environmentally friendly and wide in application prospect.

Description

Technical Field

[0001] The present invention relates to the field of durability tests of phosphogypsum-based road stabilizing materials, and particularly to a device for accelerating the formation of thaumasite in phosphogypsum by electric pulses. Background Art

[0002] Phosphogypsum (PG) is a by-product generated during the wet production of phosphoric acid by reacting phosphoric lime with sulfuric acid in chemical plants. Its main component is CaSO4·2H2O, accounting for more than 90% of its total composition. In addition, phosphogypsum also contains phosphorus, fluorine, organic matter and other impurities. For every 1t of phosphoric acid produced, 4.5 - 5.5t of phosphogypsum is generated. In recent years, the production of phosphogypsum in China has been increasing year by year, while the utilization rate of the by-product phosphogypsum has increased relatively slowly. If phosphogypsum is used in road construction to prepare phosphogypsum-based road stabilizing materials, it can not only consume a large amount of phosphogypsum, but also significantly reduce the construction cost of roads, with remarkable social and economic benefits.

[0003] Since the main component of phosphogypsum is CaSO4·2H2O, which is rich in sulfates, compared with cement-based materials, it is more likely to undergo an erosion reaction. The erosion reaction product is thaumasite (CaCO3·CaSiO3·CaSO4·15H2O). This erosion is called thaumasite-type sulfate attack, abbreviated as TSA attack. TSA attack is a relatively special type of sulfate attack. Its most significant feature is that during the erosion process of phosphogypsum-based road stabilizing materials, the continuously formed thaumasite causes the C-(A)-S-H gel in the materials to be damaged, gradually transforming the phosphogypsum-based road stabilizing materials into grayish-white mud-like or paste-like substances without gelling properties, thereby causing a sharp reduction in the mechanical properties of the road stabilizing materials and even completely losing their load-bearing capacity. Different from the common ettringite-type and gypsum-type sulfate attack damages, during the TSA attack damage process, the volume expansion of the phosphogypsum-based road stabilizing materials is not obvious, and obvious expansion cracks do not appear on the apparent morphology. Therefore, the harm of TSA attack has extremely strong concealment. The commonly used sulfate accelerated erosion method is the dry-wet cycling method, which cannot be used to accelerate TSA attack at low temperatures. Some studies have used the method of immersing specimens in a high-concentration MgSO4 solution at low temperatures to accelerate the erosion of specimens. The specimens formed thaumasite after 365 days, but there was no obvious mud-like substance, so it could not be verified that TSA attack had occurred.

[0004] Currently, many scholars at home and abroad have applied electric fields to the erosion research of cement-based materials. For example, they have studied the migration and chemical reaction processes of sulfates in cement-based materials under an electric field environment. Lorente et al. studied the influence of an electric field on SO4 2–Migration; Wang Chong et al. applied pulsed electric fields to accelerate the TSA erosion of cement-based materials, studied that the electric field could accelerate the migration of ions, and speed up the internal chemical reactions of cement-based materials, achieving the effect of accelerating TSA erosion. However, at present, no scholars have applied pulsed electric fields to the field of phosphogypsum-based road stabilizing materials. The device of the present invention applies pulsed electric fields to accelerate the formation of ettringite in phosphogypsum-based road stabilizing materials, providing a method and reference device for exploring the TSA erosion of phosphogypsum-based road stabilizing materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a device and method for accelerating the formation of ettringite in phosphogypsum by electric pulses, aiming at the defects that it is difficult to simulate TSA erosion under low-temperature acceleration in the prior art and it is difficult to verify TSA erosion in phosphogypsum-based materials.

[0006] The present invention is realized by the following technical solutions: A device for accelerating the formation of ettringite in phosphogypsum by electric pulses, comprising a generator, a curing box and a power cord; Among them: the inner groove of the curing box includes a baffle and an electrode plate. The positive and negative electrodes of the generator are respectively connected to both ends of the electrode plate through the power cord. The electrode plate and the baffle divide the inner groove of the curing box into three sections; the upper part of the electrode plate is connected to the baffle. The baffle is made of waterproof non-conductive material, the electrode plate is made of conductive material, and a plurality of holes are evenly arranged on the electrode plate. The side surface of the electrode plate is covered with a waterproof film.

[0007] The inner surface of the curing box is covered with a layer of PE film, and the thickness of the curing box is not less than 2 mm.

[0008] Preferably, the thickness of the PE film is 0.02 - 0.03 mm.

[0009] The material of the curing box is acrylic board.

[0010] The groove shape of the curing box is set according to the shape after the connection of the electrode plate and the baffle.

[0011] Each section of the curing box is 150 mm.

[0012] The material of the baffle is EVA.

[0013] The material of the electrode plate is titanium electrode plate, and the thickness of the electrode plate is 1 - 2 mm.

[0014] Preferably, the upper part of the electrode plate is connected to the baffle through insulating glue.

[0015] Preferably, the insulating glue is G704 strong glue.

[0016] Preferably, the power cord is bonded to the generator with conductive adhesive, and the power cord is bonded to the electrode plate with conductive adhesive.

[0017] The usage method of the device for accelerating the formation of thaumasite in phosphogypsum by electric pulse includes the following steps: Step S1: Prepare and form a specimen of phosphogypsum-based road stabilizing material into a ∅150mm×150mm cylindrical specimen by static pressure method according to JTG E51—2009 "Test Procedures for Inorganic Binder Stabilized Road Stabilizing Materials in Highway Engineering", and demold the specimen after molding.

[0018] Step S2: After demolding the specimen obtained in Step S1, place it into the device for accelerating the formation of thaumasite in phosphogypsum by electric pulse, and then place the specimen and the device into a standard curing box for curing; Step S3: Add NaOH solution into the device, adjust the pH of the NaOH solution and the specimen to be the same with water, adjust the pulse voltage, pulse frequency and electric pulse action time of the electric pulse generator, and start to accelerate the formation of thaumasite in phosphogypsum.

[0019] In the said Step S1, the optimum moisture content of the phosphogypsum-based road stabilizing material is 7.0~13.0%, and the maximum dry density is 1.70~2.10g / cm 3 .

[0020] In the said Step S3, the pulse voltage is 20~40V, the pulse frequency is 20~40s, and the electric pulse action time is 14d.

[0021] Preferably, after the specimen is formed in Step S1, it is demolded after being placed for 8h.

[0022] Preferably, in Step S2, the temperature of the standard curing box is 20℃±2℃, and the relative humidity ≥95%.

[0023] Preferably, in Step S2, the specimen and the device are placed in the standard curing box for curing for 28d.

[0024] Preferably, in Step S3, the mass fraction of the NaOH solution is 0.01%~0.40%.

[0025] Preferably, in Step S3, the pH of both the NaOH solution and the specimen is 11.00~13.00.

[0026] Preferably, the said usage method further includes Step S4 and S5: Step S4: Standardly cure the same specimen of phosphogypsum-based road stabilizing material for 28d, place it in the NaOH solution with the same concentration as that in Step S3 for curing, and conduct conventional erosion; Step S5: Determine the unconfined compressive strength of two groups of specimens according to JTG E51—2009 "Test Procedures for Inorganic Binder Stabilized Road Stabilizing Materials in Highway Engineering".

[0027] Determine the unconfined compressive strength of two groups of specimens according to the relevant regulations in JTG E51—2009 "Test Procedures for Inorganic Binder Stabilized Road Stabilizing Materials in Highway Engineering". The ratio of the unconfined compressive strength of the specimens accelerated by electric pulse erosion to the unconfined compressive strength of the specimens not accelerated by electric pulse erosion is called the electric promotion coefficient, which is used to characterize the degree of TSA erosion acceleration of phosphogypsum-based road stabilizing materials after electric pulse, so as to verify whether the electric pulse can accelerate the formation of thaumasite in phosphogypsum-based road stabilizing materials.

[0028] Compared with the prior art, the beneficial effects of the present invention include: 1. The structure of the device for accelerating the formation of thaumasite in phosphogypsum by electric pulse in the present invention is simple, energy-saving and environmentally friendly, easy to install and disassemble, and provides a device and a usage method for studying the formation of thaumasite in phosphogypsum-based road stabilizing materials by electric pulse, which is beneficial to the durability test of phosphogypsum road materials and promotes the resource utilization of phosphogypsum in the road industry.

[0029] 2. The device of the present invention generates a test pulse voltage with a fixed frequency by a pulse generator. The power cord connects the pulse generator to the porous electrode plates at both ends of the phosphogypsum-based road stabilizing material specimen. The electric pulse accelerates the migration of sulfate ions in the phosphogypsum-based road stabilizing material through the electric field potential difference, and the waterproof baffle prevents the NaOH solution from eroding the specimen from above the specimen.

[0030] 3. The present invention uses NaOH solution to adjust the pH value of the solutions on both sides of the specimen to be the same as that of the specimen, thereby avoiding the influence of pH during the migration of sulfate ions. Description of the Drawings

[0031] Figure 1 It is a schematic structural diagram of the device for accelerating the formation of thaumasite in phosphogypsum by electric pulse; Figure 2 It is the three views of the device for accelerating the formation of thaumasite in phosphogypsum by electric pulse, Figure 2 (a) is the front view, Figure 2 (b) is the left view, Figure 2 (c) is the top view; Figure 3 It is a sectional view with the section plane parallel to the front plane of the device for accelerating the formation of thaumasite in phosphogypsum by electric pulse; Figure 4 It is a sectional view with the section plane parallel to the side plane of the device for accelerating the formation of thaumasite in phosphogypsum by electric pulse; In the attached drawing reference numerals: 1 - generator; 2 - curing box; 3 - power cord; 4 - baffle; 5 - electrode plate; 6 - waterproof film. Detailed implementation mode

[0032] The present invention will be further described in detail below in conjunction with the attached drawings and specific embodiments.

[0033] Drug reagents: EVA is a copolymer of ethylene - vinyl acetate; The phosphogypsum - based road stabilizing material contains 90% - 95% phosphogypsum, 0 - 5% silica fume, 0 - 5% cement, and 0 - 2% slaked lime; The insulating glue is G704 strong glue, purchased from Dongguan Gupai New Material Technology Co., Ltd.; The conductive glue is purchased from Shenzhen Ausbond Co., Ltd.; The structural schematic diagram of the device for accelerating the formation of thaumasite in phosphogypsum by electric pulse of the present invention is as Figure 1 , and the device includes a generator 1, a curing box 2, a power cord 3, a baffle 4 and an electrode plate 5 arranged inside the curing box 2. It is applicable to ∅150mm×150mm cylindrical specimens.

[0034] Cover the inner surface of the curing box 2 with a 0.01mm - 0.03mm PE film. After splicing the two baffles 4 and the electrode plates 5 with insulating glue respectively, insert them into the curing box 2, and divide the inner groove of the curing box 2 into three sections, each section being 150mm.

[0035] Pad a waterproof film in the area between the two baffles 4. Take out one side of the baffle 4 and the electrode plate 5, and re - insert them after the cylindrical specimen is fixed in the mold. Cover the waterproof film 6 on the upper part of the specimen, and seal the possible liquid - leakage places with insulating glue; Connect the positive and negative poles of the generator 1 to the two - side electrode plates 5 through the power cord 3. The power cord 3 is bonded to the generator 1 with conductive glue, and the power cord 3 is bonded to the electrode plate 5 with conductive glue. Set the pulse voltage of the adjustable generator 1 to 20 - 40V and the pulse frequency to 20 - 40s.

[0036] The material of the curing box 2 is acrylic board; the shape of the groove of the curing box 2 is set according to the shape after the connection of the electrode plate 5 and the baffle 4; the material of the baffle 4 is EVA; the material of the electrode plate 5 is a titanium electrode plate with a thickness of 1 - 2mm. The insulating glue is G704 strong glue; For the detection of multiple specimens, a parallel connection method can be adopted with the same electric pulse generator.

[0037] Example 1 The mass fractions of the components in the phosphogypsum - based road stabilizing material are 90% phosphogypsum, 3% silica fume, 5% cement, and 2% slaked lime; the optimum moisture content is 10.6%, and the maximum dry density is 1.88g / cm 3 .

[0038] The phosphogypsum-based road stabilizing material was prepared into ∅150mm×150mm cylindrical specimens by the static pressure method in accordance with JTG E51—2009 "Test Procedures for Inorganic Binder Stabilized Road Stabilizing Materials in Highway Engineering", and demolded after being placed for 8 hours.

[0039] After the specimens were demolded, they were put into the simulation test device for the formation of calcium carboalumosilicate in the phosphogypsum-based road stabilizing material accelerated by electric pulse. The specimens and the device were placed together in standard curing box 2, and the temperature of curing box 2 was 22°C and the relative humidity was 97%, and cured for 28 days.

[0040] Add a NaOH solution with a mass fraction of 0.10% to the device to adjust the pH of the solutions on both sides of the specimens to be consistent with the pH of the specimens, both being 12.42. Adjust the test pulse voltage of the electric pulse generator 1 to 20V, the pulse frequency to 20s, and the electric pulse action time to 14 days.

[0041] After the phosphogypsum-based road stabilizing material specimens with the same mix ratio were cured under standard conditions for 28 days, they were placed in a NaOH solution with the same concentration for 14 days for conventional erosion for comparison.

[0042] After 14 days, take them out, and determine the unconfined compressive strength of the two groups of specimens according to the relevant regulations in JTG E51—2009 "Test Procedures for Inorganic Binder Stabilized Road Stabilizing Materials in Highway Engineering". The ratio of the unconfined compressive strength of the specimens eroded by electric pulse acceleration to the unconfined compressive strength of the specimens not eroded by electric pulse acceleration is called the electric promotion coefficient.

[0043] The unconfined compressive strength of the phosphogypsum-based road stabilizing material specimens accelerated by electric pulse is 8.97MPa, and the electric promotion coefficient is 0.95.

[0044] Example 2 The mass fractions of the components in the phosphogypsum-based road stabilizing material are 90% phosphogypsum, 5% silica fume, and 5% cement; the optimum moisture content is 12.6%, and the maximum dry density is 1.81g / cm 3 .

[0045] The phosphogypsum-based road stabilizing material was prepared into ∅150mm×150mm cylindrical specimens by the static pressure method in accordance with JTG E51—2009 "Test Procedures for Inorganic Binder Stabilized Road Stabilizing Materials in Highway Engineering", and demolded after being placed for 8 hours.

[0046] After the specimens were demolded, they were put into the simulation test device for the formation of calcium carboalumosilicate in the phosphogypsum-based road stabilizing material accelerated by electric pulse. The specimens and the device were placed together in standard curing box 2, and the temperature of curing box 2 was 21°C and the relative humidity was 96%, and cured for 28 days.

[0047] Add a NaOH solution with a mass fraction of 0.03% to the device, and adjust the pH values of the solutions on both sides of the specimen and the pH value of the specimen to be the same, both being 11.83. Adjust the test pulse voltage of the electric pulse generator 1 to 30 V, the pulse frequency to 30 s, and the electric pulse action time to 14 d.

[0048] After standard curing the specimens of phosphogypsum-based road stabilizing materials with the same mix proportion for 28 d, place them in a NaOH solution with the same concentration for 14 d for conventional erosion for comparison.

[0049] After 14 d, take them out, and determine the unconfined compressive strength of the two groups of specimens according to the relevant regulations in JTG E51—2009 "Test Procedures for Inorganic Binder Stabilized Road Stabilizing Materials in Highway Engineering". The ratio of the unconfined compressive strength of the specimens accelerated by electric pulse erosion to the unconfined compressive strength of the specimens not accelerated by electric pulse erosion is called the electric promotion coefficient.

[0050] The unconfined compressive strength of the specimens of phosphogypsum-based road stabilizing materials accelerated by electric pulse is 8.22 MPa, and the electric promotion coefficient is 0.93.

[0051] Example 3 The mass fractions of the components in the phosphogypsum-based road stabilizing materials are 91.5% phosphogypsum, 3% silica fume, 4% cement, and 1.5% slaked lime; the optimum moisture content is 11.8%, and the maximum dry density is 1.72 g / cm 3 .

[0052] Prepare and form the phosphogypsum-based road stabilizing materials into ∅150 mm×150 mm cylindrical specimens by the static pressure method according to JTG E51—2009 "Test Procedures for Inorganic Binder Stabilized Road Stabilizing Materials in Highway Engineering", and demold after placing for 8 h.

[0053] After the specimens are demolded, put them into the device for simulating the formation of calcium carboalumosilicate in phosphogypsum-based road stabilizing materials accelerated by electric pulse. Put the specimens and the device together into the standard curing box 2, the temperature of the curing box 2 is 20 °C, and the relative humidity is 97%, and cure for 28 d.

[0054] Add a NaOH solution with a mass fraction of 0.30% to the device, and adjust the pH values of the solutions on both sides of the specimen and the pH value of the specimen to be the same, both being 12.87. Adjust the test pulse voltage of the electric pulse generator 1 to 30 V, the pulse frequency to 40 s, and the electric pulse action time to 14 d.

[0055] After standard curing the specimens of phosphogypsum-based road stabilizing materials with the same mix proportion for 28 d, place them in a NaOH solution with the same concentration for 14 d for conventional erosion for comparison.

[0056] Take them out after 14 days, and determine the unconfined compressive strength of the two groups of specimens according to the relevant regulations in JTG E51—2009 "Test Procedures for Inorganic Binder Stabilized Road Stabilizing Materials in Highway Engineering". The ratio of the unconfined compressive strength of the specimens accelerated by electric pulse erosion to the unconfined compressive strength of the specimens not accelerated by electric pulse erosion is called the electric promotion coefficient.

[0057] The unconfined compressive strength of the specimen of phosphogypsum-based road stabilizing material accelerated by electric pulse is 8.94 MPa, and the electric promotion coefficient is 0.95.

[0058] Example 4 The mass fractions of each component in the phosphogypsum-based road stabilizing material are 94% phosphogypsum, 1.5% silica fume, 4% cement, and 0.5% slaked lime; the optimum moisture content is 7.2%, and the maximum dry density is 2.08 g / cm 3 .

[0059] Prepare and form the phosphogypsum-based road stabilizing material into ∅150mm×150mm cylindrical specimens by static pressure method according to JTG E51—2009 "Test Procedures for Inorganic Binder Stabilized Road Stabilizing Materials in Highway Engineering", and demold after placing for 8 h.

[0060] After the specimens are demolded, put them into the simulation test device for the formation of calcium carboalumosilicate hydrate in the phosphogypsum-based road stabilizing material accelerated by electric pulse. Put the specimens and the device together into the standard curing box 2, the temperature of the curing box 2 is 21°C, and the relative humidity is 97%, and cure for 28 d.

[0061] Add 0.02% NaOH solution to the device to adjust the pH values of the solutions on both sides of the specimens and the pH value of the specimens to be the same, which is 11.76. Adjust the test pulse voltage of the electric pulse generator 1 to 40 V, the pulse frequency to 20 s, and the electric pulse action time to 14 d.

[0062] After the specimens of the phosphogypsum-based road stabilizing material with the same mix ratio are cured under standard conditions for 28 d, place them in the NaOH solution with the same concentration for curing for 14 d for conventional erosion for comparison.

[0063] Take them out after 14 days, and determine the unconfined compressive strength of the two groups of specimens according to the relevant regulations in JTG E51—2009 "Test Procedures for Inorganic Binder Stabilized Road Stabilizing Materials in Highway Engineering". The ratio of the unconfined compressive strength of the specimens accelerated by electric pulse erosion to the unconfined compressive strength of the specimens not accelerated by electric pulse erosion is called the electric promotion coefficient.

[0064] The unconfined compressive strength of the specimen of phosphogypsum-based road stabilizing material accelerated by electric pulse is 8.01 MPa, and the electric promotion coefficient is 0.92.

[0065] As can be illustrated by the above examples, in the pulse voltage range of 20 - 40V, the higher the voltage, the faster the occurrence rate of thaumasite - type erosion in the specimens of phosphogypsum - based road stabilizing materials, and the more severe the erosion degree; in the pulse period of 20 - 40s, under the action of a short - cycle electric field of 20s, the thaumasite - type erosion of the specimens is more severe. To sum up, high - intensity and high - frequency electric pulses can accelerate the formation of thaumasite in phosphogypsum - based road stabilizing materials, thus leading to a deeper degree of thaumasite - type erosion in the specimens.

[0066] The above embodiments are only applicable to illustrate the present disclosure, rather than a limitation thereof. For those of ordinary skill in the relevant technical field, without departing from the embodiments of the present disclosure, all equivalent technical solutions also fall within the scope of the present disclosure. The patent protection scope of the present disclosure shall be defined by the claims.

Claims

1. An apparatus for accelerating the formation of thaumasite in phosphogypsum by electric pulses, characterized in that, It includes a generator (1), a curing box (2) and a power cord (3); Among them: The inner groove of the curing box (2) includes a baffle (4) and an electrode plate (5). The positive and negative electrodes of the generator (1) are respectively connected to both ends of the electrode plate (5) through the power cord (3). The electrode plate (5) and the baffle (4) divide the inner groove of the curing box (2) into three sections; The upper part of the electrode plate (5) is connected to the baffle (4). The baffle (4) is made of waterproof non-conductive material, the electrode plate (5) is made of conductive material, and a plurality of holes arranged evenly are provided on the electrode plate (5). The side surface of the electrode plate (5) is covered with a waterproof film (6).

2. The device for accelerating the formation of thaumasite in phosphogypsum by electric pulse according to claim 1, wherein, The inner surface of the curing box (2) is covered with a layer of PE film, and the thickness of the curing box (2) is not less than 2 mm.

3. The electric pulse accelerating device for the formation of thaumasite in phosphogypsum according to claim 1, wherein The material of the curing box (2) is acrylic board.

4. The device for accelerating the formation of ettringite in phosphogypsum by electric pulses according to claim 1, wherein, The groove shape of the curing box (2) is set according to the shape after the connection of the electrode plate (5) and the baffle (4).

5. The device for accelerating the formation of ettringite in phosphogypsum by electric pulses according to claim 1, wherein Each section of the curing box (2) is 150 mm.

6. The device for accelerating the formation of ettringite in phosphogypsum by electric pulse according to claim 1, wherein, The material of the baffle (4) is EVA.

7. The device for accelerating the formation of ettringite in phosphogypsum by electric pulse according to claim 1, characterized in that, The material of the electrode plate (5) is a titanium electrode plate, and the thickness of the electrode plate (5) is 1 - 2 mm.

8. The method for using the device for accelerating the formation of ettringite in phosphogypsum by electric pulses according to claims 1-7, characterized in that, It includes the following steps: Step S1: Prepare and form a specimen of phosphogypsum-based road stabilizing material into a ∅150 mm×150 mm cylinder specimen by the static pressure method according to JTG E51—2009 "Test Procedures for Inorganic Binder Stabilized Road Stabilizing Materials in Highway Engineering", and demold the specimen after it is formed; Step S2: After demolding the specimen obtained in Step S1, put it into the device for accelerating the formation of thaumasite in phosphogypsum, and then put the specimen and the device into the standard curing box (2) for curing; Step S3: Add NaOH solution into the device, adjust the pH of the NaOH solution and the specimen to be the same with water, adjust the pulse voltage, pulse frequency and electric pulse action time of the electric pulse generator (1), and start accelerating the formation of thaumasite in phosphogypsum.

9. The usage method according to claim 8, characterized in that, In the step S1, the optimum moisture content of the phosphogypsum-based road stabilizing material is 7.0 - 13.0%, and the maximum dry density is 1.70 - 2.10 g / cm 3 .

10. The method of use according to claim 8, wherein In Step S3, the pulse voltage is 20 - 40 V, the pulse frequency is 20 - 40 s, and the electric pulse action time is 14 d.

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