JP5536509B2 - Lightweight fireproof insulation cement mortar - Google Patents

Description

  The present invention relates to a lightweight fireproof and heat insulating mortar using pearlite as a lightweight aggregate.

Conventionally, the use of fire-resistant mortar containing asbestos has been banned, making it difficult to produce fire-resistant mortar with excellent fire resistance, economy, and workability. RABT (Richtlinien fur die Ausstattung und den
Betrieb von Strassentunneln: The development of fire-resistant mortars that meet the standards of the German Ministry of Transport, regulations on road tunnel equipment and traffic), and that are excellent in economic efficiency and workability are desired. Fire-resistant compositions such as various fire-resistant mortars Development is underway.
As a lightweight aggregate of the refractory composition, one using pearlite is known (for example, see Patent Document 1).

Perlite is obtained by crushing, firing, and foaming raw stones (perlite before processing) such as obsidian, pearlite, and pine sebite, also called natural glass.
Perlite used as a lightweight aggregate has a melting point as high as 1200 degrees Celsius to 1300 degrees Celsius, a specific gravity as low as 0.2, and has been used as an aggregate for fireproof mortar.

  As an example of the composition of the refractory mortar containing this pearlite, there is, for example, a combination of 463.0 kg of cement, 219.6 kg of pearlite (volume 1200 l), 396 kg of water, 0.9 kg of methylcellulose as a thickener, and a total of 10795 kg.

JP 2004-299959 A

By the way, when applying the fireproof mortar containing pearlite as a lightweight aggregate of the above-mentioned composition, it is necessary to make the coating thickness of 15 mm or less once. If the thickness is greater than that, there is a risk of material separation.
As described above, the fire-resistant mortar using only the lightweight aggregate as the aggregate and pearlite as the lightweight aggregate is likely to cause separation of the material, and it is difficult to produce a uniform material.

Moreover, in the above-mentioned blending, methylcellulose as a thickener is used as an additive (admixture) for preventing the separation of the material, but this is not sufficient to prevent the separation of the material.
In addition to methylcellulose, hydroxypropylcellulose, cellulose ester, and the like are known as thickeners for improving the workability of cement mortar.

Moreover, although it is not necessarily for refractory mortar using a lightweight aggregate, an additive for preventing breathing in which aluminum sulfate is added to hydroxyethyl cellulose is known.
In addition, plastering mortar for light coating is known in which cellulose ethers as thickeners are added together with fly ash, gypsum, slag, and a sulfonic acid dispersant. Also known is a combination of hydroxypropylmethylcellulose and a triazine fluidizer as an additive for preventing the separation of underwater concrete. These additives were not sufficient to prevent material separation in the refractory mortar described above.

  An object of the present invention is to provide a light-weight fireproof and heat-insulating cement mortar that includes pearlite as a lightweight aggregate and can sufficiently suppress the separation of materials.

In order to solve the above-mentioned problem, the lightweight refractory heat insulating cement mortar according to claim 1 includes cement, pearlite, water, and an additive for suppressing separation thereof,
Said additive, seen contains hydroxypropyl methylcellulose, and calcium aluminate,
The hydroxypropyl methylcellulose / cement ratio is in the range of 0.1 wt% to 5 wt%, the calcium aluminate / cement ratio is in the range of 0.01 wt% to 5 wt%, and the pearlite / cement ratio is It is characterized by being 20 to 150% by weight .

  In the invention according to claim 1, by using a combination of hydroxypropylmethylcellulose and calcium aluminate as additives, in a lightweight fireproof insulation cement mortar containing pearlite as a lightweight aggregate, the material can be easily used. Mixing is possible, and separation of materials can be suppressed. Therefore, the uniformity of the lightweight fireproof heat insulation hardened | cured material which hardened the lightweight fireproof heat insulation cement mortar can be improved. This also increases the uniformity of the thermal conductivity in the lightweight fireproof and heat-cured cured product, and in a fire where high heat is generated, the thermal conductivity is non-uniform, resulting in a difference in the internal expansion coefficient and the fireproof coating layer. Can be reliably prevented from causing internal destruction or explosion.

By setting the hydroxypropylmethylcellulose / cement ratio and the calcium aluminate / cement ratio in the above ranges, separation of the lightweight refractory heat-insulating cement mortar can be effectively suppressed.
When the hydroxypropylmethylcellulose / cement ratio is less than 0.1% by weight and the calcium aluminate / cement ratio is less than 0.01% by weight, it is difficult to sufficiently suppress material separation.

In addition, when the hydroxypropylmethylcellulose / cement ratio is more than 5% by weight and the calcium aluminate / cement ratio is more than 5% by weight, it is difficult to desire further improvement of the material separation inhibiting effect. Cost increase due to an increase in calcium aluminate becomes a problem. Moreover, there is a possibility that problems may occur in the workability and the properties of the cured product.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, the additive is a dispersion obtained by dissolving and dispersing the hydroxypropylmethylcellulose and the calcium aluminate in water. To do.

In the invention according to claim 2, since the additive is not in the form of powder but in the form of a dispersion, it can be easily dispersed when mixing the material of the lightweight refractory heat insulating cement mortar. Can be added either before adding water, before adding water and mixing, or after starting mixing in the production of lightweight fireproof and heat-insulating cement mortar, and the addition time can be selected according to the work situation .

  ADVANTAGE OF THE INVENTION According to this invention, separation of the material in the lightweight fireproof heat insulation cement mortar containing pearlite as a lightweight aggregate can be prevented, and a highly uniform lightweight fireproof heat insulation hardened | cured material can be obtained, and it utilizes effectively as a fireproof heat insulation material. be able to.

The RBAT60 heating curve as a heating method in the fireproof performance test of the Example of this invention is shown. It is a graph which shows the test result of Example 1 of the fire resistance performance test of the shield segment which used the lightweight fireproof heat insulation cement mortar of the Example of this invention as the fireproof coating layer. It is a graph which shows the test result of Example 1 of the fire resistance performance test of the shield segment which used the lightweight fireproof heat insulation cement mortar of the Example of this invention as the fireproof coating layer. It is a graph which shows the test result of Example 2 of the fire resistance performance test of the shield segment which used the lightweight fireproof heat insulation cement mortar of the Example of this invention as the fireproof coating layer. It is a graph which shows the test result of Example 2 of the fire resistance performance test of the shield segment which used the lightweight fireproof heat insulation cement mortar of the Example of this invention as the fireproof coating layer. It is a graph which shows the test result of Example 3 of the fire resistance performance test of the shield segment which used the lightweight fireproof heat insulation cement mortar of the Example of this invention as the fireproof coating layer. It is a graph which shows the test result of Example 3 of the fire resistance performance test of the shield segment which used the lightweight fireproof heat insulation cement mortar of the Example of this invention as the fireproof coating layer. It is a graph which shows the test result of the fire resistance performance test of the shield segment used as a comparative example. It is a graph which shows the test result of the fire resistance performance test of the shield segment used as a comparative example.

Embodiments of the present invention will be described below.
The lightweight fireproof and heat insulating cement mortar of this embodiment is composed of cement, pearlite, water and additives (admixtures) for preventing separation thereof.
As the cement of this example, various known cements can be used. For example, various Portland cements can be used.
The pearlite in this example is obtained by crushing, firing, and foaming raw stones (perlite before processing) such as obsidian, pearlite, and pinestone, which are also called natural glass, as described above. That is, the pearlite in this example is foamed pearlite after processing. In addition, pearlite has different characteristics such as whether there are many closed cells or many open cells due to the difference in raw materials. In this example, oblite with excellent quality stability based on the above characteristics is used as the raw material. It is preferable to use perlite.

  In this example, granular pearlite is used, and the average particle size of pearlite is preferably 0.5 mm to 25.0 mm, for example, and is 0.5 mm to 3.0 mm. And are preferred. Moreover, although the specific gravity of pearlite is about 0.2, for example, various pearlites baked as described above can be used, and pearlite having a different specific gravity can also be used.

The pearlite / cement ratio is preferably 20% to 150% by weight, more preferably 35% to 75% by weight. Moreover, it is preferable that the content of pearlite is set so that the specific gravity of the lightweight fireproof heat insulating cement mortar forming the fireproof coating layer 4 is in the range of 0.5 to 0.8. When the specific gravity is less than 0.5, the content of lightweight pearlite increases, and it may be difficult to disperse the pearlite substantially uniformly and cure, or the fireproof coating layer 4 may become brittle. That is, when the above pearlite / cement ratio exceeds 150% by weight, the strength may be extremely lowered.
If the specific gravity is greater than 0 or 8, the content of lightweight pearlite decreases, so that there are fewer voids due to pearlite and the heat insulation performance may be reduced.

The water / cement ratio is preferably 30% to 70% by weight, more preferably 40% to 60% by weight.
The admixture in this example is obtained by adding a calcium aluminate solution to hydroxypropylmethylcellulose. Hydroxypropyl methylcellulose is a water-soluble polymer, and the admixture can be handled as a solution.It can be easily mixed in a lightweight refractory thermal insulation cement mortar before curing. Can be set freely.

The hydroxypropyl methylcellulose / cement ratio is 0.1% to 5% by weight.
Further, the calcium aluminate / cement ratio is set to 0.001 wt% to 5 wt%.
In the concentration range of these hydroxypropylmethylcellulose and calcium aluminate, the effect of suppressing the separation of pearlite can be confirmed. When it is lower than the lower limit of these concentration ranges, the effect of suppressing the separation of the lightweight refractory heat insulating cement mortar becomes insufficient. Further, when the concentration is made higher than the upper limit of these concentration ranges, the effect of suppressing the separation of the lightweight refractory heat insulating cement mortar reaches its peak, and the cost increase due to an increase in the amount added becomes a problem.
The ratio of hydroxypropyl methylcellulose to calcium aluminate is preferably 0.05 to 10.0 for calcium aluminate with respect to hydroxypropylmethylcellulose 1.

In such a lightweight refractory heat insulating cement mortar, the aggregate / cement ratio (weight) is smaller than that of general concrete because pearlite is a lightweight aggregate. That is, even if the amount of the lightweight aggregate having a small specific gravity is increased, the weight is small, and the aggregate / cement ratio is small. In general concrete, for example, the aggregate / cement ratio is 7 (7: 1) or more, but the fireproof coating material of this example is, for example, about 1 (1: 1), but such low The admixture (additive) of this example effectively acts on the mortar of the aggregate / cement ratio.
As mentioned above, pearlite is a member that contains many voids due to foaming, so the apparent specific gravity is about 0.2, which is considerably lower than water, and it is extremely difficult to mix pearlite with cement and water. However, by using the admixture of this example, it is possible to uniformly mix pearlite and suppress separation. Further, since this admixture does not have a large viscosity, the workability does not deteriorate due to deterioration of fluidity and the like. Therefore, the workability is improved as compared with the case where a general thickener is used as an admixture for preventing separation. The admixture may contain components other than hydroxypropylmethylcellulose and calcium aluminate, but the other components are preferably water-soluble, and the admixture can be handled as a solution.

In this lightweight fireproof and heat insulating cement mortar, separation is suppressed by using the above-mentioned admixture, and there is almost no difference in density between the upper side and the lower side of the cured product obtained by curing this lightweight fireproof and heat insulating cement mortar. It becomes a state which is not seen, and it is possible to form the lightweight fireproof heat insulation hardened | cured material with very high uniformity.
Thus, the uniformity of the material of a lightweight fireproof heat insulation hardened | cured material is ensured, and the balance of the heat conductivity indispensable for fireproof heat insulation is ensured. This is a very important and required technology for products intended for thermal insulation. For example, if the material is in a non-uniform state, the thermal conductivity will be different in the lightweight refractory hardened and cured product system, and the way in which heat is transmitted will be different. A difference in temperature occurs, and based on this, a state in which the expansion coefficient differs is generated. There is a risk of causing internal destruction and explosion caused by it. On the other hand, the fireproof coating layer of this example has high fireproof performance due to high internal uniformity.

  As described above, in the conventional refractory mortar containing pearlite, for example, when methylcellulose or the like is used as a conventional admixture, if the thickness of the refractory mortar is larger than about 15 mm, the pearlite is clearly In order to isolate | separate, it was difficult to make thickness of the fireproof coating layer which consists of fireproof mortar thicker than about 15 mm. Therefore, it has been difficult to improve the heat insulation performance by increasing the thickness of the fireproof coating layer. It was also difficult to increase the pearlite content to increase the internal porosity and improve the heat insulation performance. Furthermore, when conventional methylcellulose was used as an admixture, water separation (breathing) was observed as the cement hardened.

  On the other hand, the thickness of the fireproof coating layer formed of the lightweight fireproof heat insulating cement mortar of this example is, for example, about 30 mm, and is, for example, twice as thick as the conventional fireproof mortar using pearlite. Thermal insulation performance can be improved. Further, if necessary, a highly uniform state can be maintained even if the thickness of the fireproof coating layer 4 is 100 mm or more. Moreover, heat insulation performance can be improved by increasing the content of pearlite and increasing the porosity. At this time, as described above, separation of pearlite and water is suppressed by the admixture, so that a fire-resistant coating layer with extremely high uniformity can be formed and fire resistance can be improved.

  As a method of using such a lightweight fireproof heat insulating cement mortar, there is a fireproof heat insulating coating. For example, in a steel structure such as a steel structure, the outer surface of a steel material such as a steel frame is prevented by a spraying method or the like in order to prevent the strength of the iron from drastically decreasing in a short time due to high temperatures during a fire. A fireproof coating layer is formed throughout. For this fireproof coating layer, the light weight fireproof insulation cement mortar of this example can be used.

Also, in concrete structures, generally, high-strength, high-density concrete has a tendency to explode due to a sudden rise in temperature due to a fire, etc., and the water accumulated in the concrete, such as bound water, expands. Because of this, fireproof coating may be required. For example, in a shield tunnel for roads where secondary lining is omitted, when the shield segment exposed by omitting secondary lining becomes hot due to a vehicle fire, the concrete constituting the shield segment explodes. In order to avoid this, a fireproof coating layer is formed on the inner peripheral surface of the shield segment. It is possible to use the light-weight fireproof insulating cement mortar of this example for the fireproof coating layer.
It is also possible to use this lightweight fireproof heat insulating cement mortar as a heat insulating material for external heat insulation in a reinforced concrete building.

Moreover, as a form at the time of use of this lightweight fireproof thermal insulation cement mortar, use as a material sprayed by the spraying method as mentioned above, or use as a fireproof thermal insulation panel (fireproof board) by curing and forming into a plate shape Can be mentioned.
Furthermore, when a fireproof coating layer is provided on the surface of the concrete as described above, after the lightweight fireproof insulation cement mortar is hardened and formed into a layered (plate-like) shape, the concrete is placed on the hardened material. The component enters the voids of the hardened pearlite, and the hardened material and the concrete are integrated.

This makes it possible to form a fire-resistant coating layer on the concrete surface during concrete placement, and saves on-site construction work rather than spraying the concrete after it has hardened or forming a fire-resistant coating layer later by fixing the fire plate. Can be reduced.
In addition, when building a concrete shield segment in order to construct a road shield tunnel that omits secondary lining, a fireproof coating layer in which the lightweight fireproof insulation cement mortar of this example is cured is used as a formwork. It is good also as what manufactures and uses the shield segment which the fireproof coating layer adhered integrally by arrange | positioning and placing concrete used as a shield segment on a fireproof coating layer.
By performing primary lining of the shield tunnel with the shield segment having the fireproof coating layer, the inner peripheral surface of the shield segment constituting the shield tunnel is in a state where fireproof coating is performed. Therefore, in shield tunnel construction, it is not necessary to apply fireproof coating later on the part where the shield segment has already been assembled, or by using a fire-resistant plate, and it is possible to save labor on site work in shield tunnel construction. it can.

  In addition, since it is not necessary to perform fireproof coating later, the construction period can be shortened. In addition, since it is not necessary to perform fireproof coating on the part of the shield tunnel that has already been assembled, there is no need to install fireproof coating in the shield tunnel that is being constructed. Therefore, it is possible to improve the workability in the shield tunnel by reducing the facilities in the shield tunnel where there is a limit.

In addition, the shield segment made of precast concrete is manufactured at a factory, for example. At this time, the segment main body can be manufactured by manufacturing the fireproof coating layer and joining the concrete to the fireproof coating layer. By manufacturing a shield segment with a fireproof coating layer at the factory, it is possible to stabilize the quality of the shield segment, and it is also possible to easily eliminate defective products at the quality control level at the factory. It is possible to prevent problems in the construction of the fireproof coating on site.
Moreover, it can prevent that a fireproof coating layer and a segment main body adhere with high adhesive force, and a fireproof coating layer peels off.

  In addition, in a shield tunnel provided by a shield segment having a fireproof coating layer, there may be a risk of damage to the fireproof coating layer in the event of a vehicle fire. In this case, repair is necessary. Because it is possible to spray using the lightweight fireproof insulation cement mortar of this example used for the coating layer, for example, only the damaged part of the fireproof coating layer is peeled off, and the lightweight fireproof insulation cement mortar is sprayed on this part Thus, the fireproof coating layer can be repaired.

  At this time, the components of the existing fireproof coating layer portion and the restored new fireproof coating layer are in substantially the same state, and it is possible to ensure the original fireproof performance also in the repaired portion, It is possible to ensure high uniformity with the existing part, and it is possible to restore to a very close state before the fire.

[1] Fire resistance test of shield segment In this example, a fire resistance test of a shield segment used in a P & PC (Prestressed & Precast Concrete) segment construction method is performed. In the P & PC segment construction method, after assembling a concrete segment (segment body 3) embedded in advance with a sheath communicating with each segment along the circumferential direction, the PC steel material is inserted into the sheath from the notch provided in one of the segments. By inserting a strand of PC steel and fixing the tension, prestress is introduced in the circumferential direction into a ring composed of segments.
This example has a fireproof coating layer made of lightweight fireproof thermal insulation cement mortar, made of concrete with the same composition as the P & PC segment mentioned above, and pre-stressed as PC steel by unbonded PC steel wire and PC steel bar The test specimens were subjected to a fire resistance performance test according to the RABT60 heating curve, and the temperature of each part of the test specimen was measured, and the behavior of the test specimen in explosion and fireproof coating was observed.

(A) Specimen The test specimen is made of a single concrete, and the specimen of Example 1 in which a fireproof coating layer is provided by attaching a panel fireproof plate with an anchor pin, is also made of a single concrete and sprayed. The specimen of Example 2 provided with a fireproof coating layer by the above, and the two concretes were fixed by tension with PC steel, and the specimen of Example 3 provided with a fireproof coating layer by spraying, and the two concretes were tensioned by PC steel. A comparative test body that was fixed and not provided with a fireproof coating layer was used.

Each test body corresponds to a shield segment made of reinforced concrete, and has a length of 2000 mm, a width of 600 mm, and a thickness of 400 mm (thickness not including the fireproof coating layer).
The reinforcing bars are D22 for the main bars and D13 for the loop bars.
The concrete has a slump flow of 65 cm, an air volume of 2%, a water binder ratio of 30.8%, and S / a of 52.3%. The concrete composition is 116 kg / m ³ cement, 160 kg / m ³ water, fine aggregate 340 kg / m ³ , coarse aggregate 310 kg / m ³ , and admixture 54 kg / m ³ .

The compressive strength of the concrete was 87.5 N / mm ² (wood 28 days), the moisture content was 4.1% (dried at 105 degrees Celsius for 6 days), and the density was 2430 kg / m ³ . .
The concrete curing method is pre-curing 2 hours, steam curing (temperature increase 15 degrees or less / hour, 40 degrees Celsius constant temperature holding 4 hours, temperature decrease 15 degrees or less / hour).

  The PC steel material (tensor) is one unbonded PC steel wire (diameter (φ) 21.8 mm) and four PC steel bars (diameter (φ) 32 mm). The unbonded PC steel strand reproduces the tension fixation of the shield segment in the P & PC segment, and the PC steel rod is used to reproduce the pressure acting on the shield tunnel.

Further, a polyethylene sheath (inner diameter 42 mm) for wire and a steel sheath (inner diameter 45 mm) are embedded in the concrete from unbonded PC steel.
Further, a tension of 480 kN × 1 = 480 kN is applied to the unbonded PC steel wire, and a tension of 350 kN × 4 = 1400 kN is applied to the PC steel bar.

The fireproof covering material is made of the light-weight fireproof and heat insulating cement mortar of the above example, and contains pearlite, and contains hydroxypropylmethylcellulose and calcium aluminate as an admixture for preventing separation.
In Example 1, lightweight fireproof heat insulating cement mortar was molded into a panel fireproof plate and cured, and the length was 2000 mm, the width was 600 mm, and the thickness was 30 mm corresponding to the size of the concrete specimen. ing.

The composition of the light-weight fireproof heat insulating cement mortar constituting the fireproof plate of Example 1 excluding water is, by weight, an early-strength Portland cement 55%, pearlite 39%, and the above-described admixture containing hydroxypropylmethylcellulose and calcium aluminate. 6%.
The density of the fireproof plate made of this lightweight fireproof heat insulating cement mortar is 450 kg / m ³ .
This refractory plate is fixed to a concrete specimen by anchor pins (diameter (φ) 4 mm, length 60 mm).

  In addition, the composition of the lightweight fireproof thermal insulation cement mortar for spraying of Examples 2 and 3 is 70% of an inorganic admixture composed of an admixture containing 25% of ordinary Portland cement, pearlite and calcium aluminate. %, And 5% is an organic admixture composed of an admixture containing hydroxypropylmethylcellulose.

In addition, in spraying concrete on a specimen, a mesh bar of 100 mm × 100 mm made of stainless steel (a direction corresponding to the tunnel circumferential direction (direction along the strand of PC steel) has a diameter (φ) of 1.2 mm. The mesh line in the axial direction perpendicular to it has a diameter (φ) of 2.0 mm) is fixed to the specimen with an anchor pin (diameter (φ) 4 mm, length 25 mm), and this mesh line is attached. A fireproof coating layer having a thickness of 30 mm is formed by spraying the above-mentioned lightweight fireproof and heat insulating cement mortar on the surface of the test specimen.
The moisture content of the fire-resistant coating layer that was sprayed and cured was 3.5% (105 degrees Celsius, dried for 4 days), and the density was 900 kg / m ³ .

(B) Test method The test uses a horizontal member heating test apparatus (internal furnace dimensions: length 4000 mm, width 4000 mm, depth 2000 mm, lining: ceramic fiber board, heat source: city gas) of the National Institute for Building Science. I went.
(1) Heating method Heating was performed according to the RABT60 heating curve. The measurement of the heating temperature was measured and controlled at a position 1000 mm away from the specimen using a K thermocouple with a diameter of 1.6 mm having class 2 performance defined in JIS C 1602 (thermocouple). The RABT60 heating curve is shown in FIG.
(2) The temperature measurement method of each part of the test body was measured using a K thermocouple with a diameter of 0.65 mm having class 2 performance defined in JIS C 1602 (thermocouple).
The measurement positions are the surface of the concrete specimen (the portion covered with the fireproof coating layer) TC1, the back face TC7 of the specimen, and TC2 in which the positions are shifted in order from the surface side to the back inside the specimen. TC6. The positions of TC2 to TC6 are separated from the surface side in this order.
The distances from the surface are 0 mm for TC1, 66 mm for TC2, 100 mm for TC3, 175 mm for TC4, 200 mm for TC, 300 mm for TC6, and 400 mm for TC7 on the back.

  In addition, the above-mentioned K thermocouple is also attached to the unbonded PC steel strand in the sheath arranged at the center of the thickness, and TS1 and TS5 as measurement positions are located 300 mm away from the left and right ends in the length direction. Are arranged, and three measurement positions TS2 to TS4 are arranged every 350 mm therebetween.

(C) Test result FIG. 2 shows a graph of the temperature measurement result of the concrete part of the test body of Example 1, and FIG. 3 shows the temperature measurement result of the unbonded PC steel bar part of the test body of Example 1. FIG. 4 shows a graph of the temperature measurement result of the concrete part of the test body of Example 2, and FIG. 5 shows the temperature measurement result of the unbonded PC steel bar part of the test body of Example 2. FIG. 6 shows a graph of the temperature measurement result of the concrete part of the test body of Example 3, and FIG. 7 shows the temperature measurement result of the unbonded PC steel bar part of the test body of Example 3. FIG. 8 shows a graph of the temperature measurement result of the concrete part of the test body of the comparative example, and FIG. 9 shows the temperature measurement result of the unbonded PC steel bar part of the test body of the comparative example.

As shown in each graph, in the comparative example without the fireproof coating, the highest surface temperature of the specimen reached 1169 degrees Celsius, whereas in Example 1 using the fireproof plate, 221 degrees Celsius. In Example 2 and Example 3 using the fireproof coating by spraying, 100 degrees Celsius and 101 degrees Celsius, sufficient thermal insulation performance is recognized for the fireproof coating made of the lightweight fireproof thermal insulation cement mortar of this example. In addition, the internal temperature of the test body and the wire temperature were sufficiently lower than PC steel.
In addition, in the observation result by visual observation, in the comparative example, the explosion was seen on almost the entire heating side surface of the specimen, and the maximum depth of the explosion was 42 mm. In Examples 1, 2, and 3, no explosion was observed, and no change was observed on the surface after heating.

  Moreover, in Example 1, some peeling and shrinkage cracks from the specimen were observed on the fireproof plate, and in Examples 2 and 3 by spraying, no peeling was observed and shrinkage cracks were seen. In all cases, no explosion was observed.

[2] 5% Sulfuric Acid Drop Test The light-weight fireproof and heat-insulating cement mortar of the above example is used to see the durability against the exhaust gas of the automobile when the light-weight fireproof and heat-insulated cement mortar of the above example is used as a fireproof coating material on the inner peripheral surface of the shield tunnel. A test was conducted in which 5% sulfuric acid was dropped onto a plate-like test body made of

(A) The amount of the specimen weight insulating refractory cement mortar, early-strength Portland cement 50kg (519.8kg / m ^3), pearlite 18kg (187.1kg / m ^3), hydroxypropyl methylcellulose and calcium aluminate The admixture (additive) contained is 2.8 kg (29.2 kg / m ³ ) and water is 20.6 kg (214.1 kg / m ³ ).
The admixture contains 140 g of hydroxypropyl methylcellulose and 140 g of calcium aluminate.
This lightweight refractory heat-insulating cement mortar was placed in a mold having a width of 100 mm, a depth of 100 mm, and a thickness of 30 mm, and was cured at 20 degrees Celsius up to the 28th day of the batting material to obtain a test specimen.

(B) Test method 2 ml of a 5% sulfuric acid solution was dropped on the test body, and the surface state after 24 hours was observed to confirm the state before the test. Moreover, the test was done with respect to three test bodies.

(C) Test results Although the dripped part of the sulfuric acid solution turns white in all three test specimens, no abnormalities such as dents and deterioration are observed in the specimens, and it is recognized that they are resistant to exhaust gas.
In addition, regarding the mass of the test specimen before and after the test, the mass after 24 hours of dropping the sulfuric acid solution increased by 0.8 g (0.2%) from before the dropping.

[3] Aqueous test (a) Specimen The blending amount of the lightweight refractory heat-insulating cement mortar to be the specimen was the same as in the 5% sulfuric acid dropping test.
A specimen having a diameter (φ) of 100 mm × 200 mm was prepared according to JIS A 1132 “How to make a specimen for a concrete strength specimen”. At this time, the wet curing was carried out for up to 3 days, and further up to 28 days.

(B) Test method The test body was immersed for 28 days in water within a range of 20 degrees Celsius and 3 degrees Celsius, and then a compressive strength test was performed. As a comparative example, a compressive strength test was performed on a specimen before being immersed in water.

(C) Test results The compressive strength test results before immersion in water are shown in Table 1, the compressive strength test results after immersion are shown in Table 2, the average fracture strength before and after immersion, and the average unit volume mass. Table 3 shows the rate of change before and after immersion.

  As shown in Table 3, the unit volume mass after immersion was increased by 2.5% and the breaking strength was increased by 9.2% compared with that before immersion, indicating that there was sufficient water resistance.

[4] Impact resistance test An impact resistance test was performed in which a steel ball of a test specimen was dropped in order to confirm durability due to a stepping stone caused by running of a vehicle.

(A) Specimen The blending amount of the lightweight refractory heat-insulating cement mortar to be the specimen was the same as in the 5% sulfuric acid dropping test.
The test specimens were placed on a mold having a length of 300 mm, a width of 300 mm, and a thickness of 30 mm, a lightweight fireproof and heat-insulating cement mortar, demolded after 2 days, and then cured for up to 28 days.
In addition, a concrete board having the same size as the test specimen was prepared.

(B) Test method In the state where the above-mentioned concrete board is piled on the lower side of the test body, the surface is held horizontally by full support on sand (conforming to JIS A 1408), and a steel ball having a weight of 500 g is raised on the test body. It was dropped from 70 cm. The steel balls were dropped three times for each of the three test bodies.

(C) Test results Table 4 shows the test results.

  As shown in Table 4, dents were generated at the falling locations of the steel balls and slight surface peeling was observed, but no cracks were observed, and it was confirmed that the steel balls had sufficient impact resistance.

[5] Adhesion strength test In order to confirm the adhesion strength of the light-weight fireproof insulation cement mortar shown in the embodiment to the segment body of the fireproof coating layer, the lightweight fireproof insulation cement mortar is cured to form a fireproof coating layer. After placing concrete on the fireproof coating layer and integrating the concrete and the fireproof coating layer, the tensile force is applied to the fireproof coating layer and the force (destructive stress) required to peel the fireproof coating layer from the concrete is obtained. It was measured.

(A) Specimen The blending amount of the lightweight refractory heat-insulating cement mortar to be the specimen was the same as in the 5% sulfuric acid dropping test.
The test specimen is a lightweight fireproof and heat insulating cement mortar formed on a 300 mm long, 300 mm wide, 30 mm thick formwork to form a fireproof coating layer. After curing in the air for 3 days, a 100 mm thick concrete is placed thereon. After laying and curing for 28 days, portions of the fireproof coating layer were cut with a cutter at intervals of 40 mm in length and 40 mm in width in a grid pattern.

(B) Test method A steel attachment is attached to a 40 mm square portion of the test piece with a fireproof coating layer cutter with an epoxy resin, and after 30 minutes, the fireproof coating layer is peeled off (the fireproof coating layer is destroyed). Tension was applied to the steel attachment in the vertical direction.
Moreover, the above-mentioned test was done in five places of the part which cut | disconnected the fireproof coating layer with the cutter in the above-mentioned 40 mm square.

Further, the adhesion strength required for preventing the fireproof coating layer from peeling was set to 0.00035 N / mm ² .
This vertical 40 mm, lateral 40 mm, the mass of the refractory coating layer having a thickness of 30 mm, a specific gravity of 1.2 g / cm ³ of the refractory coating layer, 4 (cm) × 4 ( cm) × 3 (cm) × 1. 2 (g) = 57.6 g = 0.56 N, and the required adhesion strength per unit area is 0.56 / (40 × 40) = 0.00035 N / mm ² .

(C) Test results Table 5 shows the breaking load and breaking stress strength when the fireproof coating layer was peeled (broken), and the ratio of breaking stress / required adhesion strength.

  As shown in Table 5, a sufficient strength of 500 to 3000 times the adhesion strength necessary for preventing peeling was obtained.

[6] Bending strength test In order to confirm the follow-up performance of the refractory coating layer shown in the embodiment with respect to the displacement of the segment body, a lightweight refractory heat-insulating cement mortar is cured to form a refractory coating layer. Concrete was cast into the concrete and the concrete and the fireproof coating layer were integrated, and then the bending strength test was performed on the integrated concrete and the fireproof coating layer.

(A) Specimen The blending amount of the lightweight refractory heat-insulating cement mortar to be the specimen was the same as in the 5% sulfuric acid dropping test.
The test specimen is a fireproof coating layer formed by placing a lightweight fireproof and heat insulating cement mortar on a 400 mm long, 100 mm wide, 30 mm thick formwork. After curing for 3 days, a 100 mm thick concrete is cast thereon. Set up and cured at 20 degrees Celsius until 28th day.
(B) Test method In accordance with JIS A 1106 "Concrete bending strength test method", the follow-up performance of the fireproof coating layer to the segment body was confirmed.

The fireproof coating layer of the test specimen was placed below, the concrete layer was placed on top, and the lower face of the test specimen was supported by a round bar-shaped support material orthogonal to the longitudinal direction of the specimen at two locations spaced in the longitudinal direction of the specimen. . The distance between the support members at this time was 300 mm, and the center of this distance was the center in the longitudinal direction of the test specimen.
On the upper surface of this test body, force was applied in the vertical direction with a round bar-shaped pressing member orthogonal to the longitudinal direction of the test body at two locations spaced in the longitudinal direction of the test body. The distance between the two pressing members at this time was 100 mm, and the center of this distance was the center in the longitudinal direction of the specimen.
In addition, a test is performed on three test specimens, and a force is applied to two test specimens until a crack is generated in the fireproof coating layer. I applied.

(C) Test results Table 6 shows the test results. Even if the fireproof coating layer cracked or the specimen was destroyed, no delamination occurred between the concrete layer and the fireproof coating layer.

[7] Test on water absorption of refractory material After the light weight refractory and heat resistant material is cured to form a refractory coating layer, when concrete is placed on the refractory coating layer, moisture in the concrete moves to the refractory coating layer A test was conducted to confirm the situation.

(A) Specimen Concrete was cast on a mold having a diameter (φ) of 100 mm and a thickness of 30 mm, and cured for 3 days to prepare a specimen.
(B) Test method Using a transparent acrylic cylindrical pipe (inner diameter: 100 mm, height: 400 mm), set the test body once on the pipe, and caulk between the outer peripheral surface of the test body and the inner peripheral surface of the pipe. The material was filled and cured for 3 days. After that, with the test body down, a concrete plate is placed on the pipe test body up to a total height of 400 mm with a glass plate placed at the lower end, which is the pipe test body side, to close the opening of the pipe. did. The state in which moisture in the placed concrete moves to the fireproof coating was visually confirmed.
The concrete cast at this time had a slump of 8 cm and a water / cement ratio of 38.2%.

(C) Test results Immediately after placing the concrete, no water droplets were seen on the bottom side of the fireproof coating layer.
After 24 hours of placing the concrete, no water droplets were seen on the bottom side of the fireproof coating layer, but waterdrops were seen on the glass plate closing the fireproof coating layer side end of the pipe. In addition, water drops were observed on the inner peripheral surface of the fireproof coating layer portion of the pipe.

Claims (2)

Including cement, pearlite, water and additives that inhibit their separation;
Said additive, seen contains hydroxypropyl methylcellulose, and calcium aluminate,
The hydroxypropyl methylcellulose / cement ratio is in the range of 0.1 wt% to 5 wt%, the calcium aluminate / cement ratio is in the range of 0.01 wt% to 5 wt%, and the pearlite / cement ratio is A lightweight refractory heat-insulating cement mortar characterized by being 20% to 150% by weight. The lightweight fireproof heat insulating cement mortar according to claim 1, wherein the additive is a dispersion obtained by dissolving and dispersing the hydroxypropylmethylcellulose and the calcium aluminate in water.

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