Fiber-reinforced glass bead thermal insulation mortar as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of thermal insulation building materials, and particularly relates to fiber-reinforced glass bead thermal insulation mortar as well as a preparation method and application thereof. Raw materials of the fiber-reinforced glass bead thermal insulation mortar comprise a base material, additives, reinforced fibers and water, the base material comprises cement, glass beads and sepiolite, the additives comprise rubber powder, cellulose, an active agent, a thixotropic agent, starch ether and an air entraining agent, and the reinforced fibers comprise wood fibers, polypropylene fibers, glass fibers and carbon fibers. By adding different types of reinforcing fibers, the compressive strength and breaking strength of the vitrified micro-bead thermal insulation mortar can be effectively improved. The fibers form a net-shaped or disordered distribution structure in mortar, so that the connectivity and integrity of the interior of the material are enhanced, and the mechanical property of the material is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal insulation building materials, and more specifically relates to a fiber-reinforced vitrified microsphere thermal insulation mortar and a preparation method and application thereof. Background Art

[0002] In the current construction industry, the selection of exterior wall insulation materials is showing a diversified trend, which is mainly divided into two categories: organic and inorganic. In the field of organic insulation materials, expanded extruded polystyrene boards, expanded molded polystyrene boards, polyurethane boards and rubber-plastic insulation boards occupy the mainstream of the market. These materials occupy a leading position in the insulation market due to their advantages such as technological maturity, low raw material costs, convenience of factory production and quality controllability. However, organic insulation materials are not perfect. Their complicated construction process, high labor costs, low level of mechanized construction, long cycle, difficult maintenance, risk of falling off, poor fire resistance, poor weather resistance and insufficient strength have become bottlenecks restricting their further development.

[0003] Inorganic thermal insulation materials are increasingly favored in the field of building exterior wall thermal insulation and energy saving due to their excellent fire resistance, mechanical and durability properties, and are regarded as the future star of building energy conservation. As an important inorganic thermal insulation material, thermal insulation mortar has attracted the attention of many researchers. The composition of thermal insulation mortar is complex and delicate, mainly including cementitious materials, aggregates and various admixtures. There are many types of thermal insulation mortars on the market, among which polystyrene particle thermal insulation mortar, expanded perlite thermal insulation mortar and vitrified microsphere thermal insulation mortar are the most common. However, polystyrene particle thermal insulation mortar has slightly insufficient fire resistance and durability because the aggregate contains organic components. Although expanded perlite thermal insulation mortar is low in cost, its high water absorption rate limits its application. In contrast, vitrified microsphere thermal insulation mortar shows unique advantages. As an inorganic glassy mineral material, vitrified microspheres are processed by special technology and have the characteristics of light weight, heat insulation, fire resistance, high and low temperature resistance and aging resistance. Its physical and chemical properties are stable, it is resistant to corrosion, acid and alkali, and it has a small and uniform particle size, high porosity, and few open holes. The prepared mortar has good fluidity, simple construction, and stable quality. Therefore, vitrified microsphere insulation mortar has excellent performance in thermal insulation and is highly anticipated. However, its thermal conductivity is still higher than that of organic thermal insulation boards, and there are challenges in construction. It also has problems such as high brittleness, poor crack resistance, and poor impermeability. Therefore, how to improve its mechanical properties while meeting the requirements of thermal conductivity, and thus obtain a thermal insulation material with excellent comprehensive performance, has become a difficult problem that technicians in this field urgently need to overcome. Summary of the invention

[0004] The purpose of the present invention is to provide a fiber-reinforced vitrified microsphere thermal insulation mortar and a preparation method and application thereof, so as to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is to provide a fiber-reinforced vitrified microsphere thermal insulation mortar, wherein the raw materials include, by weight: 1000 parts of base material, 32.75 parts of admixture, 5-40 parts of reinforcing fiber and 800-960 parts of water;

[0007] The base materials include cement, vitrified microspheres and sepiolite;

[0008] The additives include rubber powder, cellulose, an active agent, a thixotropic agent, starch ether and an air entraining agent;

[0009] The reinforcing fiber includes at least one of wood fiber, polypropylene fiber, glass fiber and carbon fiber.

[0010] Furthermore, the mass ratio of the cement, the vitrified microspheres and the sepiolite is 14:10:1.

[0011] Furthermore, the cement is PO42.5 silicate cement.

[0012] Furthermore, the bulk density of the vitrified microspheres is 80-120 kg / m3, and the thermal conductivity is ≤0.048 W / (m·K).

[0013] Furthermore, the bulk density of the sepiolite is 2 to 2.5 g / cm 3 , with a specific surface area of ​​900m 2 / g.

[0014] Furthermore, the mass ratio of the rubber powder, cellulose, active agent, thixotropic agent, starch ether and air entraining agent is 60:16:44:6:4:1.

[0015] Furthermore, the bulk density of the rubber powder is 430 g / L, and the average particle size is 80 μm.

[0016] Furthermore, the rubber powder is redispersible latex powder.

[0017] Furthermore, the cellulose is hydroxypropyl methylcellulose ether.

[0018] Furthermore, the active agent is polyvinyl alcohol (PVA) or polyoxyethylene (POE).

[0019] Furthermore, the thixotropic agent is hydroxyethyl cellulose or hydroxyethyl methyl cellulose (HEMC).

[0020] Furthermore, the air entraining agent is sodium dodecyl sulfate K12 air entraining agent.

[0021] Furthermore, the length of the reinforcing fiber is 3 mm-9 mm.

[0022] The second technical solution of the present invention is to provide a method for preparing the above-mentioned fiber-reinforced vitrified microsphere thermal insulation mortar, the steps comprising:

[0023] The basic material, the admixture and the reinforcing fiber are dry-mixed and uniformly mixed, and water is added and stirred uniformly to obtain the fiber-reinforced vitrified microsphere thermal insulation mortar.

[0024] Furthermore, the stirring is firstly stirring at a rotation speed of 50-75 rpm for 2-5 min, then stirring at a rotation speed of 85-135 rpm for 1-2 min, and finally stirring at a rotation speed of 50-75 rpm for 1-2 min.

[0025] The third technical solution of the present invention is to provide an application of the above-mentioned fiber-reinforced vitrified microsphere thermal insulation mortar in the construction of energy-saving buildings.

[0026] The present invention discloses the following technical effects:

[0027] The present invention can effectively improve the compressive strength and flexural strength of the vitrified microsphere thermal insulation mortar by adding different types of reinforcing fibers (such as wood fibers, polypropylene fibers, glass fibers and carbon fibers). These fibers form a mesh or randomly distributed structure in the mortar, which enhances the internal connectivity and integrity of the material, thereby improving the mechanical properties of the material.

[0028] The fiber-reinforced glass microsphere thermal insulation mortar of the present invention can adjust the physical properties of the thermal insulation mortar, such as dry density, thermal conductivity and consistency, by adjusting the raw materials. For example, the addition of an appropriate amount of fiber can reduce the dry density of the thermal insulation mortar and improve its thermal conductivity to keep it within a reasonable range to meet the demand for building energy conservation. In addition, the presence of fiber can also change the consistency of the mortar and affect its construction performance.

[0029] The addition of fibers in the present invention not only increases the strength of the thermal insulation mortar, but also significantly improves the durability and stability of the material due to the good bonding between the fibers and the cement matrix. This helps to reduce cracks caused by temperature changes or other environmental factors and prolong the service life of the material.

[0030] The present invention provides a fiber-reinforced vitrified microsphere thermal insulation mortar with excellent comprehensive performance, which not only ensures good thermal insulation effect, but also improves the mechanical properties and other physical properties of the material, and is suitable for various energy-saving building construction needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0032] Figure 1 SEM images of M3, M4, M6 and M8 specimens, where a is M3, b is M4, c is M6, and d is M8.

[0033] Figure 2 SEM images of specimens X1, X5, X6 and X7, where a is X1, b is X5, c is X6 and d is X7.

[0034] Figure 3 SEM images of Y2, Y4, Y6 and Y8 specimens, where a is Y2, b is Y4, c is Y6 and d is Y8.

[0035] Figure 4 SEM images of L1, L2, L3 and L7 specimens, where a is L1, b is L2, c is L3, and d is L7.

[0036] Figure 5 SEM images of N1, N3, N4 and N6 test blocks, where a is N1, b is N3, c is N4, and d is N6.

[0037] Figure 6 SEM images of T2, T4, T5 and T6 specimens, where a is T2, b is T4, c is T5, and d is T6. DETAILED DESCRIPTION

[0038] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0039] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0040] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0041] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0042] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0043] The cement used in the specific embodiment of the present invention is PO42.5 silicate cement, the physical property parameters of which are shown in Table 1, and the main components are shown in Table 2.

[0044] Table 1

[0045]

[0046]

[0047] Table 2

[0048]

[0049] The sepiolite used in the specific embodiment of the present invention is a commercially available product provided by Hunan Mingmin New Materials Technology Co., Ltd., with a bulk density of 2 to 2.5 g / cm 3 The specific surface area is 900m 2 / g, and its main chemical components are shown in Table 3.

[0050] Table 3

[0051]

[0052] The vitrified microspheres used in the specific implementation scheme of the present invention are provided by Hunan Mingmin Technology Co., Ltd., and the specific performance parameters are shown in Table 4.

[0053] Table 4

[0054]

[0055] In a specific embodiment of the present invention, the cellulose used is hydroxypropyl methylcellulose ether, which is provided by Henan Tianchen Biological Co., Ltd., and its specific properties are shown in Table 5; the active agent used is specifically polyvinyl alcohol (PVA); the thixotropic agent used is hydroxyethyl cellulose (HEC), which is provided by Guangzhou Core New Materials Co., Ltd.; the starch ether used is provided by Shandong Hongshun New Materials Co., Ltd.; the air entraining agent used is sodium dodecyl sulfate (k12 air entraining agent), which is provided by Ningbo Zhongshuike Chemical Technology Co., Ltd.; the rubber powder used is a redispersible latex powder, and its physical property parameters are shown in Table 6; the rubber powder used is a redispersible latex powder, with a bulk density of 430 g / L and an average particle size of 80 μm.

[0056] Table 5

[0057]

[0058] Table 6

[0059] project Performance parameters Appearance White powder, free flowing Solid content / % 99±1 Grayscale (800℃) / % 10±2 Bulk density / (g / L) 430±100 Average particle size / μm 80 50% aqueous solution viscosity / (Pa.s) 0.5～2.0 pH 6～8 Minimum film forming temperature / ℃ -5

[0060] Unless otherwise specified, the "parts" referred to in the specific embodiments of the present invention are "parts by mass", and the "room temperature" and "normal temperature" involved all refer to 20°C-30°C.

[0061] The preparation method of fiber reinforced vitrified microsphere thermal insulation mortar comprises the following steps:

[0062] S1. Dry mix (50 rpm) the base material, admixture and reinforcing fiber to obtain a dry mix;

[0063] S2. Add water to the dry mixture in step S1, and then stir at a rotation speed of 60 rpm for 5 minutes, then stir at a rotation speed of 130 rpm for 2 minutes, and finally stir at a rotation speed of 60 rpm for 2 minutes to obtain a fiber-reinforced vitrified microsphere insulation mortar.

[0064] Test example

[0065] The above-prepared insulation mortar was allowed to stand at room temperature for 15 minutes, and then slowly injected into the mold to ensure that the mortar was slightly higher than the edge of the test mold. The mold was a 70.7mm×70.7mm×70.7mm and 40mm×40mm×160mm steel triple test mold that was easy to disassemble. Before use, an appropriate amount of mold release agent was evenly applied to the inner wall of the test mold. Then, the tamping rod was gently used to evenly tamp 25 times in a spiral direction from outside to inside. This process should be operated with caution to avoid damaging the vitrified micro-bead aggregate. After standing for 10 minutes, the mortar that was higher than the edge of the test mold was cut off and smoothed with a spatula. The test block was placed in an environment with a temperature of (23±2)℃ and a relative humidity of (50±10)%, covered with a plastic film, and removed after three days of mold curing. Then, the standard curing was continued for 28 days.

[0066] 1. Determination of dry density

[0067] According to the national standard GB / T 5486, the dry density is determined by the following method:

[0068] Place the sample in an electric constant temperature air drying oven, adjust the oven temperature to (105±5)℃, and continue drying until it reaches a constant weight.

[0069] The dry density of the specimen is calculated according to formula (1), and the average of the test results of the three specimens is taken as the final dry density value. The final result is accurate to 0.1kg / m 3 :

[0070]

[0071] Where ρ0 is the dry density, kg / m 3 , accurate to 0.1; m0 is the drying mass of the specimen, g; V is the volume of the specimen, mm 3 .

[0072] 2. Mechanical properties test

[0073] The compressive strength test was carried out according to GBT 17671-1999 standard. The test specimens used were 40mm×40mm×160mm in size and were taken out after 28 days of curing in the fully automatic curing room. Before the test, the surface of the test block was ensured to be dry and free of moisture. Then the compressive strength test was carried out using a DYE-300 digital pressure testing machine. Three groups were measured and the average value was calculated.

[0074] The compressive strength of thermal insulation mortar is calculated according to formula (2):

[0075]

[0076] In the formula, R C is the compressive strength of the mortar cube specimen, MPa; F C is the maximum load when the specimen is damaged, N; A is the pressure-bearing area of ​​the specimen, mm 2 .

[0077] According to the GBT 17671-1999 standard process, the flexural strength of the test block was tested. The test block size was 40mm×40mm×160mm. The testing equipment was a DYE-300 digital flexural testing machine. Three groups were tested and the average value was calculated.

[0078] 3. Determination of thermal conductivity

[0079] According to GB / T 10297-2015 standard, the transient hot-wire method (Hot-wire) was used to measure the thermal conductivity of the steel sheet using a TC3000E thermal conductivity meter (Xi'an Xiaxi Electronic Technology Co., Ltd.). Three groups were tested and the average value was calculated.

[0080] 4. Consistency test

[0081] According to the JGJ / T 70-2009 standard, the consistency of the mortar was measured, three groups were tested, and the average value was calculated. First, ensure that the measuring instrument is in good condition and the slide rod slides smoothly. Then pour the mortar mixture into the measuring container at one time. The mortar surface needs to be slightly lower than the container mouth by about 10mm. Then, use the tamping rod to tamp evenly 25 times and tap the container to make the surface flat. After that, adjust the position of the measuring rod through the brake screw so that the lower end of the measuring rod just touches the upper end of the slide rod. At the same time, the pointer is aligned with the zero point to start timing. After 10 seconds, quickly tighten the screw to make the lower end of the measuring rod touch the upper end of the slide rod again. At this time, read the sinking depth (accurate to 1mm) from the dial. This value is the mortar consistency.

[0082] 5. Microscopic morphology

[0083] Field emission scanning electron microscopy (SEM, S4800, HITACHI, Japan) was used to observe the microstructure and pore structure of the test pieces at different scales.

[0084] Example 1

[0085] The reinforcing fiber is made of wood fiber with a length between 3 and 6 mm. The raw material ratio is shown in Table 7 and the performance is shown in Table 8.

[0086] Table 7

[0087]

[0088] Table 8

[0089]

[0090] It can be seen from Table 8 that after adding wood fiber, the compressive strength of the thermal insulation mortar shows a trend of first decreasing and then gradually increasing. When the dosage exceeds 2.0%, the compressive strength continues to rise because the micro-powder structure of wood fiber can easily fill the pores of the thermal insulation mortar and the shell of the vitrified microspheres, which will reduce the voids inside the thermal insulation mortar and make the connection of the entire structure more closely connected. In addition, the wood fiber can easily fuse with the hydration products in the thermal insulation mortar, which can greatly improve the compressive strength of the thermal insulation mortar. When the wood fiber dosage is 3.5%, the flexural strength is 0.77Mpa, which is mainly because the surface of the wood fiber is relatively rough and the adhesion between it and the cementitious material is very good, which can improve the bending moment resistance of the test block section. After adding wood fiber, the dry density of the thermal insulation mortar first increases and then decreases. This is because the density of wood fiber is slightly lower than that of cement, but much greater than that of vitrified microspheres. When the proportion of wood fiber added increases, the volume of vitrified microspheres in the mortar per unit volume will decrease, resulting in a larger dry density of the thermal insulation mortar. When the amount of wood fiber added continues to increase, it replaces most of the volume occupied by cement, and the dry density of the thermal insulation mortar decreases. The addition of wood fiber also increases the thermal conductivity of the thermal insulation mortar. This is because wood fiber has a powdery structure and largely fills the pores introduced by the air entraining agent in the thermal insulation mortar, thereby enhancing the thermal conductivity of the thermal insulation mortar.

[0091] Figure 1 The SEM images of the M3, M4, M6 and M8 test blocks, where a is M3, b is M4, c is M6, and d is M8. It can be seen from the figure that the wood fiber is evenly distributed in the mortar, fully combined with the cement mortar, and can have a good filling effect on the pores of the thermal insulation mortar. When the wood fiber content is 1.5% to 2.0%, the wood fiber has a certain filling effect on the cement mortar, and the density of the thermal insulation mortar is improved. When the wood fiber content is 3.0% to 4.0%, the wood fiber can fully fill the pores in the cement mortar, and the density of the thermal insulation mortar is greatly improved. The wood fiber, cementitious materials and vitrified microspheres are closely combined, and the strength of the thermal insulation mortar is greatly improved. In addition, the density of the thermal insulation mortar is significantly improved.

[0092] Example 2

[0093] Compared with Example 1, the difference is that the reinforcing fiber is polypropylene fiber with a length of 6 mm. The properties are shown in Table 9.

[0094] Table 9

[0095]

[0096] It can be seen from the data in Table 9 that when the polypropylene fiber content is 2.0%, the compressive strength of the thermal insulation mortar reaches a maximum value of 0.73Mpa. When the polypropylene fiber content is 4.0%, the flexural strength reaches a maximum value of 0.75Mpa. The significant improvement in compressive strength and flexural strength is because the polypropylene fiber is distributed in a network in the thermal insulation mortar and is well wrapped by the thermal insulation mortar, which plays a good supporting role for the thermal insulation mortar and can be well bonded with the hydration products in the mortar. In addition, since the polypropylene fiber is crisscrossed in the thermal insulation mortar, it plays a good role in reinforcing the mortar. When the mortar is under pressure, it can well prevent the generation and development of cracks. Moreover, since the polypropylene fiber has a certain toughness, it has a high elongation at break and elastic modulus. Therefore, adding polypropylene fiber can greatly improve the compressive strength and flexural strength of the thermal insulation mortar.

[0097] When the polypropylene fiber content is 0.5% to 1.0%, the dry density of the thermal insulation mortar increases from 330.02kg / m 3 Down to 297.60kg / m 3 , reduced by 32.00kg / m 3 The decrease ratio is 10%, because the dry density of polypropylene fiber is much smaller than that of cement. After adding polypropylene fiber, it replaces part of the volume occupied by cement, and the dry density of thermal insulation mortar decreases. When the polypropylene fiber content is 1.0% to 2.0%, the dry density of thermal insulation mortar shows an increasing trend again, because with the increase of polypropylene fiber content, the friction between polypropylene fiber and vitrified microspheres will increase during the mixing process, the damage of vitrified microspheres will increase, the aggregate filling will be more dense, and the dry density of mortar will increase. When the polypropylene fiber content is 2.5%, the dry density of thermal insulation mortar decreases sharply. When the polypropylene fiber content is 3.0% to 4.0%, there is little change compared with the content of 2.0%.

[0098] When the polypropylene fiber content is 0.5% to 2.0%, the thermal conductivity of the insulation mortar continues to rise. When the polypropylene fiber content is 2% to 3%, the polypropylene fiber occupies a larger volume of the mortar. On the contrary, the volume occupied by cement is relatively small, and the thermal conductivity of the insulation mortar is reduced. When the polypropylene fiber content reaches 4%, the thermal conductivity of the insulation mortar reaches 0.0623W / (M·K).

[0099] Under the condition of constant water-to-solid ratio, with the increase of polypropylene fiber content, the consistency of thermal insulation mortar shows a trend of first increasing and then gradually decreasing. This is because when the polypropylene fiber content is small, the polypropylene fiber itself has a certain water absorption, so it will reduce the water secretion, but with the increase of polypropylene fiber content, the fiber forms a dispersed network in the thermal insulation mortar system, which reduces the flow performance of the mortar. With the increase of fiber content, the wet bulk density of the mortar gradually increases.

[0100] Figure 2 The SEM images of the X1, X5, X6 and X7 specimens, where a is X1, b is X5, c is X6, and d is X7. As can be seen from the figure, the polypropylene fiber is tightly wrapped by the cement mortar and presents a network structure distribution in the mortar. With the increase of the polypropylene fiber content, the polypropylene fiber is more densely distributed in the mortar. When the fiber content is 0.5%, due to the relatively small fiber content, it can be well wrapped by cement. When the fiber content is 2.5% to 3.0%, the probability of polypropylene fiber forming a network structure increases, which is equivalent to many micro-reinforcements embedded in the mortar, which plays a good connection role for the cement mortar, and can better transmit stress, and can bond well with the hydration products, so that the strength of the thermal insulation mortar can be greatly improved. When the polypropylene fiber content is 3.5%, the fiber distribution is more dense, but because the cementitious material wrapping the fiber has not increased, the further improvement of the thermal insulation mortar strength is limited.

[0101] Example 3

[0102] Compared with Example 1, the difference is that the reinforcing fiber is polypropylene fiber with a length of 9 mm. The properties are shown in Table 10.

[0103] Table 10

[0104]

[0105] It can be seen from the data in Table 10 that 9mm polypropylene fiber at different dosages has a great influence on the compressive strength, flexural strength, dry density, thermal conductivity and consistency of the sample: when the polypropylene fiber dosage is added from 0.5% to 1%, the compressive strength and flexural strength of the thermal insulation mortar show an upward trend, and the flexural strength is at the maximum value; the dry density increases from 288.10kg / m 3 Increased to 354.63kg / m 3 ; The thermal conductivity increased from 0.0536W / (M·K) to 0.0555W / (M·K), an increase of 3.5%. The above four properties generally show a trend of first increasing, then decreasing, and then gradually increasing with the increase of polypropylene fiber content. This is because compared with 6mm polypropylene fiber, 9mm polypropylene fiber is longer. When the content of longer polypropylene fiber is not large, even a small amount of it can play a good reinforcing role in the thermal insulation mortar. The density of polypropylene fiber is smaller than that of cement, but much larger than that of glass beads. Therefore, after adding, it will occupy the volume occupied by glass beads to a large extent. The dry density and thermal conductivity of the sample will definitely increase, and the compressive strength and flexural strength will also increase, and the mechanical properties will also increase.

[0106] When the polypropylene fiber content is 2.5% to 4%, the compressive strength, flexural strength, dry density and thermal conductivity of the insulation mortar are generally on an upward trend. When the polypropylene fiber content is 3%, the compressive strength of the insulation mortar is at a maximum value of 1MPa. This is because the polypropylene fiber forms a three-dimensional network system in the insulation mortar, which plays a good supporting role for the skeleton of the insulation mortar. In addition, since the polypropylene fiber itself has extremely strong toughness, each polypropylene fiber is randomly distributed horizontally or vertically in the insulation mortar and firmly embedded in it, making the insulation mortar have extremely strong shear resistance.

[0107] The changes in the consistency of the thermal insulation mortar are just the opposite to the changes in other properties. When the polypropylene fiber content is 0.5% to 1.5%, the consistency of the thermal insulation mortar continues to decrease. This is because the polypropylene fiber forms a dispersed network system in the thermal insulation mortar, which reduces the fluidity of the thermal insulation mortar. When the polypropylene fiber content is 1.5% to 2.5%, the consistency of the thermal insulation mortar continues to increase. This is because more polypropylene fibers occupy the volume occupied by cement to a considerable extent, which will weaken the water absorption of the thermal insulation mortar. However, the volume of the added water has not changed, which will increase the consistency of the thermal insulation mortar. When the polypropylene fiber content is 2.5% to 4%, the consistency of the thermal insulation mortar decreases again. This is because the network system formed by the polypropylene fiber plays a leading role and the fluidity of the thermal insulation mortar is reduced.

[0108] Figure 3The SEM images of the Y2, Y4, Y6 and Y8 specimens, where a is Y2, b is Y4, c is Y6, and d is Y8. As can be seen from the figure, the polypropylene fiber is firmly embedded in the thermal insulation mortar, and the hydration products generated by cement and other cementitious materials are also attached to the fiber surface. The fibers are crisscrossed in the thermal insulation mortar. When the fiber content is 1%, the fiber is embedded in the thermal insulation mortar, and the bonding between the fiber and the cementitious material is good, which can improve the bending moment resistance of the specimen. With its significant specific surface area advantage and higher elastic modulus than the binary cementitious system, the polypropylene fiber can form a wide contact surface with the binary system, thereby generating strong pulling friction and bonding force, effectively improving the flexural strength of the binary system. When the hardened binary cementitious system is subjected to external force, the expansion of the internal microcracks will be hindered by the polypropylene fiber. The fiber consumes the stress energy required for crack expansion during the pulling process, thereby delaying the further development of the crack. The polypropylene fiber is evenly distributed in the binary cementitious system, generating a strong mechanical meshing force with the surrounding matrix, forming a reverse stress field, and effectively dispersing the concentrated stress at the crack tip. When the crack tries to expand, it must overcome this stress field and consume more energy, thereby slowing down the crack expansion rate. In b, the polypropylene fiber exists in the binary system in a skewed posture. When the crack encounters the fiber, its expansion direction will undergo a complex multi-directional deflection rather than a simple unidirectional change. In this process, the fiber not only bears part of the external force, but also disperses the concentrated force to multiple directions. Therefore, the polypropylene fiber significantly enhances the flexural strength of the binary cementitious system. In c and d, when the polypropylene fiber content is 3% to 4%, the fiber is distributed more and more densely in the insulation mortar, forming a cross-distribution situation, which is equivalent to inserting a lot of micro-reinforcements in the insulation mortar, which plays a good supporting role in the skeleton of the insulation mortar. The hydration product and the polypropylene fiber are tightly bonded together to form a very good whole, which plays a very important role in improving the compressive strength of the insulation mortar.

[0109] Example 4

[0110] Compared with Example 1, the difference is that the reinforcing fiber is glass fiber with a length of 3 mm. The properties are shown in Table 11.

[0111] Table 11

[0112]

[0113] It can be seen from the data in Table 11 that when the 3mm glass fiber content ranges from 0.5% to 4%, the compressive strength of the glass bead insulation mortar varies from 0.27 to 0.7MPa. When the glass fiber content is 3.5%, the compressive strength of the insulation mortar is the largest, which is 0.7MPa. This is because when the glass fiber content reaches 3.5%, the glass fiber has a significant supporting effect on the insulation mortar, and the compressive strength of the insulation mortar gradually increases. When the 3mm glass fiber content is 0.5% to 4%, the flexural strength of the glass bead insulation mortar varies from 0.3 to 1.1MPa. When the glass fiber content is 3.5%, the flexural strength of the insulation mortar is the largest, which is 1.1MPa. As the glass fiber content increases, the flexural strength of the insulation mortar shows a trend of first changing slowly, then increasing, and then decreasing. When the glass fiber content is 0.5% to 3%, the glass fiber does not play a good connecting role on the cross section of the thermal insulation mortar. When the glass fiber content is 3.5%, it can achieve good random and uniform distribution in the thermal insulation mortar, tightly combined with the cementitious material, and form a complex network structure, thereby enhancing the mechanical bite force between the mortar and the matrix, improving the crack resistance and plastic strength of the thermal insulation mortar, effectively hindering the formation and development of microcracks, maintaining the integrity of the internal structure of the mortar, and improving the overall performance. When the 3mm glass fiber content ranges from 0% to 4%, the dry density of the vitrified microsphere thermal insulation mortar varies from 299.05 to 374.33 kg / m 3 When the glass fiber content is 3%, the dry density of the thermal insulation mortar is the smallest, which is 299.05kg / m 3 When the glass fiber content is 3.5%, the dry density of the thermal insulation mortar is the largest, which is 374.33kg / m 3. The dry density of the thermal insulation mortar shows a trend of gradually decreasing, then increasing, and then decreasing again with the increase of glass fiber content. This happens because the dry density of glass fiber is much smaller than that of cement, but much larger than that of vitrified microspheres. Therefore, after adding the thermal insulation mortar, it occupies the volume occupied by cement, which reduces the dry density of the thermal insulation mortar. However, after adding a certain amount of glass fiber, the degree of crushing of vitrified microspheres increases, and the density of the thermal insulation mortar continues to increase. If vitrified microspheres continue to be added, the degree of replacing cement increases, and the dry density of the thermal insulation mortar decreases instead. When the content of 3mm glass fiber is in the range of 0.5% to 4%, the thermal conductivity of the vitrified microsphere thermal insulation mortar varies from 0.0412 to 0.0533W / (M·K). When the glass fiber content is 1.5%, the thermal conductivity of the insulation mortar is the largest, which is 0.0533W / (M·K). When the glass fiber content is 0.5%, the thermal conductivity of the insulation mortar is the smallest, which is 0.0412W / (M·K). When the glass fiber content is 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, and 4%, the thermal conductivity of the insulation mortar is increased by 14.3%, 29.4%, 18%, 18.2%, 13.1%, 13.3%, and 21.8% respectively compared with the glass fiber content of 0.5%. The thermal conductivity of the insulation mortar shows a trend of increasing first and then decreasing with the increase of glass fiber content. This phenomenon occurs because, with the increase of glass fiber content, the degree of crushing of vitrified microspheres increases, the cavity structure of vitrified microspheres is destroyed, and the thermal insulation performance of thermal insulation mortar decreases. With the increase of glass fiber content, cement is largely replaced, and the thermal conductivity of thermal insulation mortar decreases. With the increase of glass fiber content, the consistency of thermal insulation mortar shows a downward trend overall, because glass fiber forms a dispersed network structure in thermal insulation mortar, which reduces the fluidity of thermal insulation mortar.

[0114] Figure 4The SEM images of L1, L2, L3 and L7 specimens, where a is L1, b is L2, c is L3, and d is L7. As can be seen from the figure, in a, the glass fibers are randomly distributed in the material. When the material is subjected to stress, this spatial structure is conducive to the dispersion and transmission of stress and improves the strength. In b and c, it can be clearly seen that a tight connection is formed between the root of the glass fiber and the cement matrix on the fracture surface of the sample. In the interface bonding area, there are abundant hydrated calcium silicate gel and rod-shaped calcium aluminate, and these hydration products are tightly attached to the surface of the glass fiber. The reason for this phenomenon is that the surface of the glass fiber is rich in hydroxyl groups, which can form hydrogen bonds with water molecules, thereby promoting the close bonding between the fiber and the cement matrix in the aerogel concrete. As the hydration process continues to advance, the fiber surface will continue to adsorb more hydration products, making the connection between the fiber and the cement matrix stronger, thereby significantly improving the mechanical properties of the material. In Figure d, when the glass fiber content is 3.5%, the distribution of the fibers in the mortar becomes more and more dense, and the monofilamentous glass fibers are embedded in the thermal insulation mortar, which greatly enhances the crack resistance of the thermal insulation mortar.

[0115] Example 5

[0116] Compared with Example 1, the difference is that the reinforcing fiber is glass fiber with a length of 6 mm. The properties are shown in Table 12.

[0117] Table 12

[0118]

[0119]

[0120] It can be seen from the data in Table 12 that 6mm glass fiber at different dosages has a great influence on the compressive strength, flexural strength, dry density, thermal conductivity and consistency of the sample: when the glass fiber dosage is added from 0.5% to 3%, the compressive strength and flexural strength of the thermal insulation mortar increase from 0.47MPa and 0.43MPa to 0.67MPa and 0.70MPa, respectively, with an increase of 42.6% and 62.8%, respectively. At this time, the compressive strength and flexural strength of the thermal insulation mortar are at their maximum values; the dry density increases from 330.02kg / m 3 Increased to 383.69kg / m 3, an increase of 16.3%; thermal conductivity increased from 0.0472W / MK to 0.0566W / MK, an increase of 19.9%; the above four properties generally showed a trend of first stable change, then gradual increase, and then decrease with the increase of thermal insulation mortar dosage; this is because compared with 3mm glass fiber, 6mm glass fiber is longer, and the longer glass fiber will continue to enhance the thermal insulation mortar as the dosage increases. The density of glass fiber is smaller than that of cement, but much larger than that of vitrified microspheres. When the glass fiber dosage is 0.5% to 1%, the cement dosage will be reduced, so the dry density and thermal conductivity of the sample will be slightly reduced. At this time, the compressive strength and flexural strength of the thermal insulation mortar also show a slightly decreasing trend. When the glass fiber dosage is 1% to 2%, the compressive strength, flexural strength, dry density and thermal conductivity of the thermal insulation mortar do not change much. When the glass fiber content is 2% to 3%, the compressive strength, flexural strength, dry density and thermal conductivity of the insulation mortar continue to increase. This is because the glass fiber content is large, which can continuously enhance the strength of the insulation mortar. The dry density of the insulation mortar increases and the compactness improves, which also leads to a continuous increase in the thermal conductivity of the insulation mortar. The consistency of the insulation mortar shows a trend of first decreasing, then increasing, and finally slightly decreasing. This is because the addition of glass fiber reduces the fluidity of the insulation mortar, causing the consistency to continue to decrease. When the glass fiber content is too much, the cement content will continue to decrease. At this time, the water absorption of the insulation mortar is weakened, but the amount of water added has not changed, so it will cause the fluidity of the mortar to continue to increase. When the glass fiber content is too much, the characteristics of the glass fiber itself reduce the fluidity of the insulation mortar to a certain extent.

[0121] Figure 5 The SEM images of the N1, N3, N4 and N6 specimens are shown in Figure 1, where a is N1, b is N3, c is N4 and d is N6. As can be seen from the figure, in a and b, the glass fibers are randomly distributed inside the material. In the damaged specimens, the glass fibers are broken and there are many holes on the surface of the material. This is attributed to the small diameter of the glass fibers, which enhances their air entrainment effect and thus reduces the thermal conductivity of the material. In c and d, the interface area where the fiber roots meet the cement matrix is ​​full of hydration products, mainly hydrated calcium silicate. Due to its excellent hydrophilicity, the surface of glass fibers is rich in hydroxyl groups, which can combine with water molecules in the thermal insulation mortar to form stable hydrogen bonds. These hydrogen bonds promote more complete hydration of the fiber thermal insulation mortar during the curing stage, thereby accumulating a large amount of hydration products on the fiber surface. As the hydration products continue to accumulate, they significantly enhance the static friction and bonding strength between the fiber and the cement matrix, and improve the overall density of the material. This change not only optimizes the microstructure of the material, but also improves its mechanical properties to a certain extent.

[0122] Example 6

[0123] Compared with Example 1, the difference is that the reinforcing fiber is carbon fiber with a length of 6 mm. The properties are shown in Table 13.

[0124] Table 13

[0125]

[0126] It can be seen from the data in Table 13 that with the increase of 6mm carbon fiber content, the compressive strength and flexural strength of the thermal insulation mortar continue to increase. This is because carbon fiber itself has great strength. After adding to the thermal insulation mortar, it can continuously enhance the strength of the thermal insulation mortar. When the carbon fiber content is 4%, the compressive strength and flexural strength of the thermal insulation mortar are 0.34MPa and 0.57MPa, respectively, which are 47.8% and 42.5% higher than when the carbon fiber content is 0.5%, respectively. The compressive strength and flexural strength are significantly improved. The dry density of the thermal insulation mortar shows a trend of first decreasing and then increasing with the increase of carbon fiber content. This is because the density of carbon fiber is low. After adding, it occupies the volume of cement to a certain extent, and the dry density of the thermal insulation mortar continues to decrease. However, as the carbon fiber content continues to increase, the degree of damage of the vitrified microspheres increases, so the dry density of the thermal insulation mortar continues to increase. With the increase of carbon fiber content, the thermal conductivity of the thermal insulation mortar shows a trend of first increasing and then changing slowly. This is because the addition of carbon fiber has caused the damage of the vitrified microspheres in the thermal insulation mortar to a large extent, and the thermal conductivity of the thermal insulation mortar has increased. When carbon fiber is continuously added, the effect of carbon fiber content on the thermal conductivity of the thermal insulation mortar begins to decrease. With the increase of carbon fiber content, the consistency of the thermal insulation mortar generally shows a trend of continuous decrease. This is because the addition of carbon fiber reduces the fluidity of the thermal insulation mortar and the consistency continues to decrease.

[0127] Figure 6 The SEM images of the T2, T4, T5 and T6 test blocks are shown in Figure 1, where a is T2, b is T4, c is T5 and d is T6. As can be seen from the figure, with the increase of the 6mm carbon fiber content, the carbon fiber is distributed more and more densely in the mortar, and is distributed in one direction in the mortar, which has a great effect on enhancing the strength of the thermal insulation mortar. The surface of the carbon fiber is attached with cement hydration products and is wrapped by a large amount of hydrated calcium silicate gel. It can be seen that the carbon fiber has a good bonding with the thermal insulation mortar matrix, but more carbon fibers are easy to fill the pores in the thermal insulation mortar. This is also the reason why the dry density and thermal conductivity of the thermal insulation mortar show an upward trend with the increase of the carbon fiber content.

[0128] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0129] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fiber-reinforced vitrified microsphere thermal insulation mortar, characterized in that: The raw materials include, by mass: 1000 parts of base material, 32.75 parts of admixture, 5-40 parts of reinforcing fiber and 800-960 parts of water; The base materials include cement, vitrified microspheres and sepiolite; The additives include rubber powder, cellulose, an active agent, a thixotropic agent, starch ether and an air entraining agent; The reinforcing fiber includes at least one of wood fiber, polypropylene fiber, glass fiber and carbon fiber.

2. The fiber-reinforced vitrified microsphere thermal insulation mortar according to claim 1, characterized in that: The mass ratio of the cement, vitrified microspheres and sepiolite is 14:10:1; and / or the mass ratio of the rubber powder, cellulose, active agent, thixotropic agent, starch ether and air entraining agent is 60:16:44:6:4:

1.

3. The fiber-reinforced vitrified microsphere thermal insulation mortar according to claim 1, characterized in that: The cement is PO42.5 silicate cement; and / or the bulk density of the vitrified microspheres is 80-120 kg / m 3 , thermal conductivity ≤ 0.048 W / (m·K); and / or, the bulk density of the sepiolite is 2 to 2.5 g / cm 3 , with a specific surface area of ​​900m 2 / g.

4. The fiber-reinforced vitrified microsphere thermal insulation mortar according to claim 1, characterized in that: The rubber powder has a bulk density of 430 g / L and an average particle size of 80 μm; and / or the rubber powder is a redispersible latex powder.

5. The fiber-reinforced vitrified microsphere thermal insulation mortar according to claim 1, characterized in that: The cellulose is hydroxypropyl methylcellulose ether; and / or the active agent is polyvinyl alcohol or polyoxyethylene.

6. The fiber-reinforced vitrified microsphere thermal insulation mortar according to claim 1, characterized in that: The thixotropic agent is hydroxyethyl cellulose or hydroxyethyl methyl cellulose; and / or, the air entraining agent is sodium dodecyl sulfate K12 air entraining agent.

7. The fiber-reinforced vitrified microsphere thermal insulation mortar according to claim 1, characterized in that: The length of the reinforcing fibers is 3 mm to 9 mm.

8. A method for preparing the fiber-reinforced vitrified microsphere thermal insulation mortar according to any one of claims 1 to 7, characterized in that the steps include: The basic material, the admixture and the reinforcing fiber are dry-mixed and uniformly mixed, and water is added and stirred uniformly to obtain the fiber-reinforced vitrified microsphere thermal insulation mortar.

9. The preparation method according to claim 8, characterized in that: The stirring is firstly stirring at a rotation speed of 50-75 rpm for 2-5 min, then stirring at a rotation speed of 85-135 rpm for 1-2 min, and finally stirring at a rotation speed of 50-75 rpm for 1-2 min.

10. Use of the fiber-reinforced vitrified microsphere thermal insulation mortar according to any one of claims 1 to 7 in the construction of energy-saving buildings.

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