Concrete structure thermal insulation and moisturizing curing blanket

Abstract

The present invention provides a thermal insulation and moisture-retaining maintenance blanket for concrete structures, comprising a water-absorbing material layer, capillaries, a plastic film layer, and a rubber-plastic sponge layer. The water-absorbing material layer is the bottom layer and covers the surface of a newly cast concrete structure; capillaries are laid on the water-absorbing material layer; a plastic film layer is covered on the capillaries; and a rubber-plastic sponge layer is covered on the plastic film layer. The capillaries of the present invention are connected to a water supply pipe, and water flows out through the orifices on the surface of the capillaries. Under the action of the water-absorbing material, the water is evenly distributed on the surface of the concrete structure, replenishing moisture to the surface of the concrete structure and meeting the requirement of keeping the surface of the concrete structure moist. At the same time, by adjusting the water temperature and water flow time, the temperature of the concrete structure is controlled so that the surface temperature of the concrete meets the requirement of controlling the internal and external temperature difference, that is, cracks are prevented from forming on the surface of the concrete structure through dual temperature and humidity control.

Description

Technical Field

[0001] The present invention relates to a curing blanket, in particular to a curing blanket specially used for heat preservation and moisture retention of concrete structures. The present invention belongs to the technical field of concrete structure construction and curing. Background Art

[0002] After concrete is poured, a hydration reaction occurs within it, causing the internal temperature to rise sharply, then begin to drop after reaching a certain point. When there is a large temperature difference between the inside and outside of the concrete, cracks, known as temperature cracks, can form on the surface of the concrete structure. Furthermore, excessive dryness can also easily lead to cracks. Therefore, to prevent these cracks, it is crucial to maintain the surface of the concrete structure with thermal insulation and moisture retention.

[0003] However, traditional concrete structure thermal insulation and moisture conservation measures are two independent sets of measures, each implemented separately, and the two cannot be taken into account at the same time. Moisture conservation measures involve sprinkling water on the concrete structure surface, while thermal insulation conservation measures involve covering the concrete structure surface with insulation materials. Once the concrete structure surface is covered with insulation materials, it is not convenient to sprinkle water on the surface for moisture conservation. Sprinkling water on the concrete structure surface for moisture conservation requires the concrete structure surface to be exposed, and when the concrete structure surface is exposed, it is not convenient to cover it with insulation materials for insulation conservation. Therefore, traditional thermal insulation and moisture conservation measures often cannot be taken into account at the same time. Summary of the Invention

[0004] In view of the above reasons, in order to maintain the newly poured concrete structure and prevent it from cracking, the purpose of the present invention is to provide a maintenance blanket specifically used for heat preservation and moisture retention on the surface of concrete structure, which can take into account the heat preservation and moisture retention maintenance functions.

[0005] To achieve the above object, the present invention adopts the following technical solution: a concrete structure heat preservation and moisture retention curing blanket, which includes a water-absorbing material layer, capillaries, a plastic film layer and a rubber-plastic sponge layer;

[0006] The water-absorbing material layer is the bottom layer and covers the surface of the newly poured concrete structure; the capillary tubes are laid on the water-absorbing material layer, and the capillary tubes are arranged in a serpentine shape. Orifices are opened at intervals on the surface of the capillary tubes. Water in the capillary tubes flows out through the orifices, seeps through the water-absorbing material layer, and is evenly distributed on the surface of the concrete structure; the plastic film layer is covered on the capillary tubes; and the rubber-plastic sponge layer is covered on the plastic film layer;

[0007] When the surface of the covered concrete structure is horizontal and the thermal insulation and moisture-retaining blanket is placed horizontally, the relationship between the orifice spacing d on the capillary tubes and the spacing h between two adjacent horizontal sections of the serpentine capillary tubes and the wetting radius r is:

[0008]

[0009]

[0010] Where: r is the capillary orifice wetted radius; m is the mass of the absorbent material per unit area; w is the water absorption rate of the absorbent material; ρ is the density of water; q is the capillary orifice flow rate; t is the capillary orifice outflow time;

[0011] When the surface of the covered concrete structure is inclined and the thermal insulation and moisture-retaining curing blanket is placed at an angle, the orifice spacing d of the capillary tubes and the spacing h between two adjacent horizontal sections of the serpentine-shaped capillary tubes are:

[0012] d=b

[0013] h=h 逆 +h 顺

[0014] Where: b is the horizontal wet distance perpendicular to the slope; h is the vertical wet distance; 逆 h is the wetting distance against the slope; 顺 The wetting distance along the slope is:

[0015]

[0016]

[0017]

[0018] Where r is the capillary orifice wetted radius; m is the mass of the absorbent material per unit area; w is the water absorption rate of the absorbent material; ρ is the density of water; q is the capillary orifice flow rate; t is the capillary orifice outflow time; i is the inclination angle of the thermal insulation and moisture retention blanket.

[0019] The outflow rate of each orifice on the capillary tube is equal.

[0020] Furthermore, when the heat preservation and moisture conservation blanket is placed horizontally, that is, i=0, the equivalent number of openings e at any opening position of the capillary tube is z for:

[0021]

[0022] Where: q is the orifice flow rate of the capillary tube; u is the orifice flow coefficient; g is the acceleration of gravity; K is the capillary flow modulus; d is the orifice spacing; N is the total number of capillary orifices; z is the orifice number along the direction of the capillary tube; H z+1 To follow the direction of the capillary tube, the z+1th orifice has an effective water head; e z To follow the direction of the capillary tube, the orifice is numbered as z, which is the equivalent number of openings; S 标准 is the opening area of the hole opener;

[0023] When the thermal insulation and moisturizing blanket is placed at an angle, that is, i≠0, the equivalent number of openings e at any opening position of the capillary tube is j,k for:

[0024]

[0025] Where: q is the orifice flow rate of the capillary tube; u is the orifice flow coefficient; g is the acceleration of gravity; K is the capillary flow modulus; d is the orifice spacing; c is the number of capillary horizontal layers; n is the total number of orifices in each capillary layer; (j, k) is the number of the kth orifice in the jth layer along the direction of the capillary tube; H j,k+1 The effective water head of the k+1th orifice in the jth layer is along the direction of the capillary tube; e (j,k) In the direction of the capillary tube, the orifice number is (j, k), which is the equivalent number of openings; S 标准 is the opening area of the hole opener.

[0026] Furthermore, the capillary tubes are tied to the water-absorbing material layer, the plastic film layer and the rubber-plastic sponge layer are bonded by glue, and the whole formed by the water-absorbing material layer and the capillary tubes is connected to the plastic film layer and the rubber-plastic sponge layer bonded together by a needle-free fixator to form an integral structure.

[0027] Furthermore, the thickness of the rubber-plastic sponge layer is 2cm-10cm.

[0028] Furthermore, the concrete structure thermal insulation and moisture conservation blanket includes a temperature sensor and a humidity sensor;

[0029] The temperature sensors include a temperature sensor disposed inside the concrete structure, a temperature sensor disposed below the water-absorbing material layer, close to the surface of the concrete structure, and between two adjacent sections of serpentine capillary tubes running horizontally, and a temperature sensor disposed on the top surface of the rubber-plastic sponge;

[0030] The humidity sensor includes a humidity sensor arranged below the water-absorbing material layer, close to the surface of the concrete structure, with serpentine capillaries horizontally extending between two adjacent sections, and a humidity sensor arranged on the top surface of the rubber-plastic sponge. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the top view of the concrete structure heat preservation and moisture retention curing blanket of the present invention;

[0032] Figure 2 This is a schematic side view of the heat preservation and moisture retention curing blanket for concrete structures according to the present invention;

[0033] Figure 3 This is a schematic diagram of the wetting range of the outflow from the horizontally placed capillary orifice of the present invention;

[0034] Figure 4 This is a schematic diagram of the wetting range of the outflow from the obliquely placed capillary orifice of the present invention;

[0035] Figure 5 This is a schematic diagram of the calculation of uniform outflow from a horizontally placed capillary orifice according to the present invention;

[0036] Figure 6 This is a schematic diagram of the calculation of uniform outflow from an inclined capillary orifice of the present invention;

[0037] Figure 7 A state diagram is used for the present invention. DETAILED DESCRIPTION

[0038] The structure and features of the present invention are described in detail below with reference to the accompanying drawings and embodiments. It should be noted that various modifications can be made to the embodiments disclosed herein. Therefore, the embodiments disclosed in the specification should not be regarded as limiting the present invention, but are merely examples of embodiments, the purpose of which is to make the features of the present invention apparent.

[0039] like Figure 1 、 Figure 2 As shown, the concrete structure thermal insulation and moisture-retaining blanket disclosed in the present invention comprises a water-absorbing material layer 1, capillary tubes 2, a plastic film layer 3, and a rubber-plastic sponge layer 4. The water-absorbing material layer 1 is the bottom layer, covering the surface of the freshly poured concrete structure 5. The capillary tubes 2 are laid on top of the water-absorbing material layer; the plastic film layer 3 covers the capillary tubes 2; and the rubber-plastic sponge layer 4 covers the plastic-plastic sponge layer 4. The capillary tubes 2 are tied to the water-absorbing material layer 1 with fine plastic-coated copper wire. The plastic film layer 3 and the rubber-plastic sponge layer 4 are bonded together with glue. The water-absorbing material layer 1 and capillary tubes 2 are connected to the bonded plastic film layer and rubber-plastic sponge layer via a needle-free fastener to form a monolithic structure.

[0040] The capillary tubes 2 control the surface temperature of the concrete structure, thereby controlling the temperature difference between the inside and outside of the concrete structure, as well as maintaining the concrete surface and moisture. The capillary tubes 2 are arranged in a serpentine pattern, with orifices 21 spaced apart on their surface. The capillary tubes 2 are connected to a water supply pipe 6. Water within the capillary tubes flows out through the orifices 21. To ensure uniform distribution of water across the concrete structure, a water-absorbing material layer 1 is laid beneath the capillary tubes 2. This layer can be a nonwoven fabric, geotextile, or other absorbent material. When the outside temperature is too low, causing the concrete surface temperature to drop, hot water can be introduced into the capillary tubes through the water supply pipe 6 to adjust the water temperature and control the temperature difference between the inside and outside of the concrete structure.

[0041] In actual use, the surface of the covered concrete structure may be horizontal or inclined. When the surface of the covered concrete structure is horizontal and the thermal insulation and moisture-retaining blanket is placed horizontally, Figure 3 As shown, the orifice 21 on the surface of the capillary tube 2 has a circular shape when water is discharged. When the orifice flow rate q and the orifice outflow time t are constant, if the water-absorbing material layer (such as non-woven fabric) is fully and evenly wetted, the relationship between the orifice spacing d and the spacing h between two adjacent horizontal segments of the serpentine capillary tubes and the wetting radius r is:

[0042]

[0043] Where: r is the wetted radius of the capillary orifice; m is the mass of the absorbent material per unit area; w is the water absorption rate of the absorbent material; ρ is the density of water; q is the orifice flow rate of the capillary; t is the orifice outflow time of the capillary.

[0044] The orifice spacing d and the spacing h between two adjacent horizontal sections of the water capillary are:

[0045]

[0046] When the surface of the covered concrete structure is inclined, the thermal insulation and moisture-retaining blanket covering it is also placed inclined, such as Figure 4 As shown, the wetting shape of the capillary orifice outlet is a rectangle. Let the horizontal wetting distance perpendicular to the slope be b and the wetting distance against the slope be h. 逆 , the wetting distance along the slope is h 顺 When the orifice flow rate q, orifice outflow time t and inclination angle i are constant, if the non-woven fabric is fully and evenly wetted, the orifice spacing d and the spacing h between two adjacent horizontal sections of the serpentine capillary tubes are:

[0047] d=b (3)

[0048] h=h 逆 +h 顺 (4)

[0049] Where: b is the horizontal wet distance perpendicular to the slope; h is the vertical wet distance; 逆 h is the wetting distance against the slope; 顺 The wetting distance along the slope is:

[0050]

[0051]

[0052]

[0053] Among them, r is the wetting radius of the capillary orifice; m is the mass of the water-absorbing material per unit area; w is the water absorption rate of the water-absorbing material; ρ is the density of water; q is the orifice flow rate of the capillary tube; t is the orifice outflow time of the capillary tube; i is the inclination angle of the thermal insulation and moisture-retaining maintenance blanket.

[0054] According to the structural parameters of the curing blanket, the number of capillary openings is:

[0055] Number of capillary horizontal layers c:

[0056]

[0057] Number of holes per layer n:

[0058]

[0059] Total number of orifices N:

[0060] N=c·n

[0061] Wherein: L represents the length of the thermal insulation and moisturizing maintenance blanket, and B represents the width of the thermal insulation and moisturizing maintenance blanket.

[0062] Due to the existence of head loss along the capillary tube, the head gradually decreases along the capillary tube. If the outflow rate of each orifice along the capillary tube is equal, the outflow area of each orifice needs to be adjusted. In the actual production of the curing blanket, the opening area of the hole opener is the standard value S 标准 Therefore, the present invention uses a method of opening several standard holes at the opening position to equalize the opening area, thereby ensuring that the outflow rate of each orifice of the capillary tube is equal. At any opening position of the capillary tube, the equivalent opening number e Z The method for determining is as follows.

[0063] Assume that the inclination angle of the concrete structure thermal insulation and moisture conservation blanket is i, the orifice flow rate is q, the orifice spacing is d, the capillary horizontal direction upper and lower layer spacing is h, the distance between the capillary water inlet and the first dripper is a, the capillary cross-sectional area is A, the orifice flow coefficient is u, the capillary flow modulus is K, and the area of the kth orifice in the jth layer along the capillary direction is S. j,k (j=1,2,3,...,c;k=1,2,3,...,n), along the direction of the capillary tube, the area of the zth orifice S z (z=1,2,3,...,N), the total number of orifices N, the number of capillary horizontal layers c, and the number of orifices in each layer n.

[0064] like Figure 5 As shown, when the present invention is placed horizontally, i.e., i=0, the orifice spacing along the capillary tube is equal, and the head at each orifice is equal. The difference in the effective head comes from the head loss along the way. To ensure that the outflow q of each orifice is equal, it is necessary to first ensure that the outflow of the Nth orifice is q, and the area of the Nth orifice S N Under known conditions, the orifice outflow calculation formula can be used to determine the Nth orifice effective head H N The calculation method of the head loss along the way can be used to determine the effective heads of the remaining N-1 orifices. The specific calculation method is as follows:

[0065]

[0066] The outflow area of each orifice can be determined by the outflow rate of each orifice and the effective head of each orifice. The specific calculation method is as follows:

[0067]

[0068] In the actual production process, the size of the hole opened by the hole opener is fixed, so the opening area is usually the standard value S 标准 , in order to facilitate production, the equivalent number of holes e can be used. z and standard orifice area S 标准 To equate the above orifice area calculation value S z , the specific calculation method is as follows:

[0069]

[0070] Among them: e z S represents the number of orifices along the direction of the capillary tube that is equivalent to the calculated area value of the zth orifice; z It represents the calculated value of the zth orifice area along the direction of the capillary tube.

[0071] Substituting formulas (8) and (9) into formula (10), it can be calculated that when the present invention is set horizontally, i.e., i=0, the equivalent number of openings e at any opening position of the capillary tube is z for:

[0072]

[0073] Where: q is the orifice flow rate of the capillary tube; u is the orifice flow coefficient; g is the acceleration of gravity; K is the capillary flow modulus; d is the orifice spacing; N is the total number of capillary orifices; z is the orifice number along the direction of the capillary tube; H z+1 To follow the direction of the capillary tube, the z+1th orifice has an effective water head; e z To follow the direction of the capillary tube, the orifice is numbered as z, which is the equivalent number of openings; S 标准 is the opening area of the hole opener.

[0074] like Figure 6 As shown, when the present invention is placed at an angle, i.e. i≠0, the orifice spacing along the capillary tube is not equal, and the position head of each layer of orifices is not equal. The difference in effective head comes from the head loss along the way and the position head. To ensure that the outflow q of each orifice is equal, first ensure that the outflow of the Nth orifice is q, and the orifice area S of the Nth orifice is equal. c,n Under known conditions, the orifice outflow calculation formula can be used to determine the Nth orifice effective head H c,n By calculating the head loss along the way and the head change at the position, the effective heads of the remaining N-1 orifices can be determined. The specific calculation method is as follows:

[0075]

[0076] The outflow area of each orifice can be determined by the outflow rate of each orifice and the effective head of each orifice. The specific calculation method is as follows:

[0077]

[0078] In the actual production process, the opening area is usually the standard value S 标准 In order to facilitate production, the number of holes e and the standard orifice area S can be used. 标准 To equate the above orifice area calculation value, the specific calculation method is as follows:

[0079]

[0080] Among them, e j,k S represents the number of orifices equivalent to the calculated area of the kth orifice in the jth layer along the direction of the capillary tube; j,k It represents the calculated value of the kth orifice area in the jth layer along the direction of the capillary tube.

[0081] Substituting formulas (12) and (13) into formula (14), it can be calculated that when the present invention is placed obliquely, that is, i≠0, the equivalent number of openings e at any opening position of the capillary tube is j,k for:

[0082]

[0083] Where: q is the orifice flow rate of the capillary tube; u is the orifice flow coefficient; g is the acceleration of gravity; K is the capillary flow modulus; d is the orifice spacing; c is the number of capillary horizontal layers; n is the total number of orifices in each capillary layer; (j, k) is the number of the kth orifice in the jth layer along the direction of the capillary tube; H j,k+1 The effective water head of the k+1th orifice in the jth layer is along the direction of the capillary tube; e (j,k) In the direction of the capillary tube, the orifice number is (j, k), which is the equivalent number of openings; S 标准 is the opening area of the hole opener.

[0084] In order to maintain the humidity of the surface of the concrete structure and prevent the concrete surface from drying and cracking, the capillary tubes are covered with a layer of plastic film for locking in water.

[0085] In order to prevent heat loss inside the concrete structure and reduce the temperature difference between the inside and outside of the concrete structure, the present invention covers a layer of rubber-plastic sponge with a thickness of 2cm-10cm for insulation on the plastic film layer.

[0086] The principle of the present invention for achieving thermal insulation and moisture retention of concrete structures is as follows: the capillary tube is adjacent to the water supply pipe, water flows out through the orifice on the surface of the capillary tube, and under the action of the non-woven fabric, the water flow is evenly distributed on the surface of the concrete structure, replenishing moisture to the surface of the concrete structure, meeting the requirement of keeping the surface of the concrete structure moist; at the same time, by adjusting the water temperature and water flow time in the capillary tube, the temperature of the concrete structure is controlled so that the surface temperature of the concrete meets the requirement of controlling the temperature difference between the inside and the outside, that is, cracks are prevented from occurring on the surface of the concrete structure through dual temperature and humidity control.

[0087] like Figure 1 、 Figure 2 As shown, the present invention includes temperature sensors and humidity sensors. To accurately monitor the internal and external temperatures of the concrete structure, a temperature sensor 71 is installed inside the concrete structure to measure the internal temperature. At least one temperature sensor 72 is installed between two adjacent sections of the serpentine capillary tubes, located below the water-absorbing material layer and in close contact with the concrete surface, to measure the external temperature of the concrete structure. A temperature sensor 73 is installed on the top surface of the rubber-plastic sponge to measure the ambient temperature.

[0088] In order to accurately grasp the humidity of the concrete structure surface, the present invention provides at least one humidity sensor 81 between two adjacent sections of the serpentine capillary tubes; and a humidity sensor 82 is provided on the top surface of the rubber sponge to measure the ambient humidity.

[0089] A wire groove 9 is also provided on one side of the maintenance blanket, through which the wires connected to the signal output ends of each sensor are led out.

[0090] Figure 7 As shown in the figure, when using, the curing blanket is laid on the concrete structure surface in sequence.

[0091] The advantages of the present invention are simple structure, heat preservation and moisture retention functions, and more convenient maintenance of concrete structures.

[0092] Finally, it should be noted that the embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A concrete structure thermal insulation and moisture conservation blanket, characterized by: It includes a water-absorbing material layer, a capillary tube, a plastic film layer and a rubber-plastic sponge layer; The water-absorbing material layer is the bottom layer and covers the surface of the newly poured concrete structure; the capillary tubes are laid on the water-absorbing material layer, and the capillary tubes are arranged in a serpentine shape. Orifices are opened at intervals on the surface of the capillary tubes. Water in the capillary tubes flows out through the orifices, seeps through the water-absorbing material layer, and is evenly distributed on the surface of the concrete structure; the plastic film layer is covered on the capillary tubes; and the rubber-plastic sponge layer is covered on the plastic film layer; When the surface of the covered concrete structure is horizontal and the thermal insulation and moisture-retaining blanket is placed horizontally, the relationship between the orifice spacing d on the capillary tubes and the spacing h between two adjacent horizontal sections of the serpentine capillary tubes and the wetting radius r is: Where: r is the capillary orifice wetted radius; m is the mass of the absorbent material per unit area; w is the water absorption rate of the absorbent material; ρ is the density of water; q is the capillary orifice flow rate; t is the capillary orifice outflow time; When the surface of the covered concrete structure is inclined and the thermal insulation and moisture-retaining blanket is placed at an angle, the orifice spacing d of the capillary tubes and the spacing h between two adjacent horizontal sections of the serpentine capillary tubes are: d=b h=h 逆 +h 顺 Where: b is the horizontal wet distance perpendicular to the slope; h is the vertical wet distance; 逆 h is the wetting distance against the slope; 顺 The wetting distance along the slope is: Where r is the capillary orifice wetted radius; m is the mass of the absorbent material per unit area; w is the water absorption rate of the absorbent material; ρ is the density of water; q is the capillary orifice flow rate; t is the capillary orifice outflow time; i is the inclination angle of the thermal insulation and moisture retention blanket. The outflow rate of each orifice on the capillary tube is equal.

2. The concrete structure heat preservation and moisture retention curing blanket according to claim 1, characterized in that: When the thermal insulation and moisturizing blanket is placed horizontally, that is, i=0, the equivalent number of openings at any opening position of the capillary tube is e z for: Where: q is the orifice flow rate of the capillary tube; u is the orifice flow coefficient; g is the acceleration of gravity; K is the capillary flow modulus; d is the orifice spacing; N is the total number of capillary orifices; z is the orifice number along the direction of the capillary tube; H z+1 To follow the direction of the capillary tube, the z+1th orifice has an effective water head; e z To follow the direction of the capillary tube, the orifice is numbered as z, which is the equivalent number of openings; S 标准 is the opening area of the hole opener; When the thermal insulation and moisturizing blanket is placed at an angle, that is, i≠0, the equivalent number of openings e at any opening position of the capillary tube is j,k for: Where: q is the orifice flow rate of the capillary tube; u is the orifice flow coefficient; g is the acceleration of gravity; K is the capillary flow modulus; d is the orifice spacing; c is the number of capillary horizontal layers; n is the total number of orifices in each capillary layer; (j, k) is the number of the kth orifice in the jth layer along the direction of the capillary tube; H j,k+1 The effective water head of the k+1th orifice in the jth layer is along the direction of the capillary tube; e (j,k) To follow the direction of the capillary tube, the orifice number is the equivalent number of openings at (j, k); S 标准 is the opening area of the hole opener.

3. The concrete structure heat preservation and moisture retention curing blanket according to claim 1 or 2, characterized in that: The capillaries are tied to the water-absorbing material layer, the plastic film layer and the rubber-plastic sponge layer are bonded by glue, and the whole formed by the water-absorbing material layer and the capillaries is connected to the plastic film layer and the rubber-plastic sponge layer bonded together by a needle-free fixator to form an integral structure.

4. The concrete structure heat preservation and moisture retention curing blanket according to claim 3, characterized in that: The thickness of the rubber-plastic sponge layer is 2cm-10cm.

5. The concrete structure heat preservation and moisture retention curing blanket according to claim 4, characterized in that: Includes temperature sensor and humidity sensor; The temperature sensors include a temperature sensor disposed inside the concrete structure, a temperature sensor disposed below the water-absorbing material layer, close to the surface of the concrete structure, and between two adjacent sections of serpentine capillary tubes running horizontally, and a temperature sensor disposed on the top surface of the rubber-plastic sponge; The humidity sensor includes a humidity sensor arranged below the water-absorbing material layer, close to the surface of the concrete structure, with serpentine capillaries horizontally extending between two adjacent sections, and a humidity sensor arranged on the top surface of the rubber-plastic sponge.

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