Artificial lightweight aggregate with high heat capacity, high strength, low water absorption and surface reactivity as well as preparation method and application of artificial lightweight aggregate

Abstract

The invention provides an artificial lightweight aggregate with high heat capacity, high strength, low water absorption and surface reactivity. The aggregate comprises an inner core which is selected from shale lightweight aggregate of which the normal-pressure water absorption rate is not lower than 20% and the particle size is 1-2mm; the phase change material is adsorbed in the holes of the inner core through the capillary action of the holes in the surface of the inner core; the polymer encapsulation layer is used for adsorbing the surface of the inner core with the phase change material to form a flexible thin film to prevent leakage of the phase change material and is used as a buffer layer when the volume of the phase change material is changed due to phase change or temperature change; the transition layer is coated on the polymer encapsulation layer, so that the peripheral alkalinity is reduced, and the polymer encapsulation layer is prevented from being eroded by alkali; the transition layer is coated with the shell, the strength of the artificial lightweight aggregate is improved, the water absorption rate is reduced, and therefore the working performance and strength of concrete or mortar are improved. The artificial lightweight aggregate has the heat capacity of 1100-1200 J / (kg.K), the cylinder compressive strength of 6.0-7.0 MPa, the water absorption rate of less than 7% and the loose bulk density of less than 900 kg / m < 3 >.

Description

Technical Field

[0001] The present invention relates to the field of construction industry, and more particularly to an artificial lightweight aggregate having high heat capacity, high strength, low water absorption and surface reactivity. Background Art

[0002] Aggregates are essential materials in the construction industry, widely used in foundations, roadbeds, drainage culverts, and concrete. Aggregates are categorized into standard and lightweight aggregates. Lightweight aggregates are suitable for producing lightweight bricks and other lightweight building products, offering excellent thermal and sound insulation properties. Traditionally, aggregate production relies on ore crushing, but this often results in environmental damage, and mines are often located far from demand centers. To address environmental concerns, artificial aggregates, including artificial lightweight aggregates, are emerging as new sources of aggregate materials.

[0003] Existing artificial lightweight aggregate products have a density range similar to natural lightweight aggregate, but the manufacturing process typically uses sintered natural minerals such as expanded clay and shale, resulting in energy-intensive production and greenhouse gas emissions. Lightweight aggregate concrete is widely used in building components with high insulation requirements, such as exterior walls and panels, leveraging its low thermal conductivity to slow heat exchange between interior and exterior spaces, thereby improving insulation. However, reducing thermal conductivity only slows heat transfer, limiting its effectiveness in improving insulation.

[0004] Therefore, there is an urgent need in the art to develop artificial lightweight aggregates for construction that can further enhance the effect of stabilizing indoor temperature, thereby reducing indoor temperature fluctuations and avoiding significant changes in indoor temperature due to changes in the temperature of the external environment. The present invention aims to address these needs. Summary of the Invention

[0005] The purpose of the present invention is to provide an artificial lightweight aggregate, a preparation method or an application thereof that solves the above technical problems.

[0006] According to a first aspect of the present invention, there is provided an artificial lightweight aggregate having high heat capacity, high strength, low water absorption and surface reactivity. In particular, the aggregate comprises: The inner core is selected from shale lightweight aggregate with a water absorption rate of not less than 20% at normal pressure and a particle size of 1-2 mm; a phase change material, wherein the phase change material is adsorbed into the pores of the core through capillary action of the surface pores of the core; A polymer encapsulation layer, which is used to form a flexible film on the surface of the core having the phase change material adsorbed thereon to prevent leakage of the phase change material and to serve as a buffer layer when the phase change material undergoes phase change or volume change due to temperature change; a transition layer, the transition layer being coated on the polymer encapsulation layer to reduce the alkalinity of the periphery thereof to prevent the polymer encapsulation layer from being corroded by alkali; and an outer shell, the outer shell being coated on the transition layer to enhance the strength of the artificial lightweight aggregate and reduce the water absorption rate of the artificial lightweight aggregate, thereby enhancing the workability and strength of concrete or mortar using the artificial lightweight aggregate; The artificial lightweight aggregate has a heat capacity of 1100-1200 J / (kg·K), a cylinder compressive strength of 6.0-7.0 MPa, a water absorption rate of less than 7%, and a heat resistance of less than 900 kg / m 3 loose bulk density.

[0007] According to one embodiment of the present invention, the phase change material is selected from polyethylene glycol, lauric acid or a combination thereof.

[0008] According to one embodiment of the present invention, the polymer encapsulation layer is composed of ethylene-vinyl acetate copolymer emulsion.

[0009] According to one embodiment of the present invention, the transition layer is selected from zeolite powder or metakaolin, or a mixture of the two in any proportion.

[0010] According to one embodiment of the present invention, the shell includes cement, silica fume and hydrophilic nano-silica.

[0011] According to one embodiment of the present invention, the transition layer can react with the calcium hydroxide in the shell to generate calcium silicate hydrate gel.

[0012] According to one embodiment of the present invention, the shell can provide the surface of the artificial lightweight aggregate with chemical reactivity, so that it can react with the cement base to produce calcium hydroxide to form calcium silicate hydrate gel, thereby strengthening the bonding force between the artificial lightweight aggregate and the cement base.

[0013] According to a second aspect of the present invention, a construction mortar with high heat capacity, high strength and low thermal conductivity is provided, which comprises, by weight, 100-150 parts of cement, 20-40 parts of fly ash, 200-250 parts of river sand, 50-70 parts of water, and 60-100 parts of the artificial lightweight aggregate as described above, the total of which is 450-470 parts.

[0014] According to one embodiment of the present invention, the mortar has a 28-day compressive strength of 40-50 MPa, a heat capacity of 1100-1200 J / (kg·K) and a thermal conductivity of 0.4-0.5 W / (m·K) at a temperature of 35-45°C.

[0015] According to a third aspect of the present invention, there is provided a building concrete having high heat capacity, high strength and low thermal conductivity, comprising, by weight, 300-350 parts of cement, 150-200 parts of fly ash, 50-60 parts of silica fume, 360-400 parts of shale aggregate with a density grade of 500 and a particle size of 5-15 mm, 160-200 parts of shale aggregate with a density grade of 700 and a particle size of 0-5 mm, 160-180 parts of water, 8-12 parts of an admixture, and 200-240 parts of the artificial lightweight aggregate as described above, the total of which is 1480-1540 parts.

[0016] According to one embodiment of the present invention, the concrete has a 28-day compressive strength of 45-55 MPa, a heat capacity of 1000-1100 J / (kg·K) and a thermal conductivity of 0.2-0.4 W / (m·K) at a temperature of 35-45°C.

[0017] According to a fourth aspect of the present invention, there is provided a method for preparing an artificial lightweight aggregate having high heat capacity, high strength, low water absorption and surface reactivity, comprising: Heat the core and phase change material to 100-110°C and 60-70°C respectively; Evenly mixing the core and the phase change material so that the phase change material is adsorbed into the surface pores of the core, and then cooling the core to room temperature; The mixture is uniformly mixed with an ethylene-vinyl acetate copolymer emulsion and placed in an environment with a temperature of 20-30°C and a humidity of 50-80% for 120-180 minutes to form a polymer encapsulation layer; adding zeolite powder or metakaolin and allowing it to adsorb onto the polymer encapsulation layer to form a transition layer; and Then, the material is added into a granulator with cement, silica fume, hydrophilic nano-silica and water for granulation to form a shell on the transition layer, thereby obtaining artificial lightweight aggregate.

[0018] According to one embodiment of the present invention, the method further comprises curing the artificial lightweight aggregate with steam at 60-80° C. and 1 atmosphere of pressure for 24 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings, in which:

[0020] Figure 1 A schematic structural diagram of an artificial lightweight aggregate having high heat capacity, high strength, low water absorption and surface reactivity according to one embodiment of the present invention is shown;

[0021] Figure 2 Shows the cooling curves for different aggregates;

[0022] Figure 3 Shows the cooling curves of the mortar (control 1, control 2, sample 1) after heating; DETAILED DESCRIPTION

[0023] In the following description, an artificial lightweight aggregate having high heat capacity, high strength, low water absorption and surface reactivity, a manufacturing method and / or application are listed as preferred examples. It will be apparent to those skilled in the art that modifications including additions and / or substitutions may be made without departing from the scope and spirit of the invention, and specific details may be omitted so as not to obscure the invention; however, this disclosure is prepared to enable those skilled in the art to practice the disclosure herein without undue experimentation.

[0024] According to a first aspect of the present invention, an artificial lightweight aggregate is provided that has high heat capacity, high strength, low water absorption, and surface reactivity. More particularly, the artificial lightweight aggregate has both low thermal conductivity and high heat capacity to further enhance indoor temperature stabilization. The artificial lightweight aggregate comprises the following components: The inner core is composed of shale lightweight aggregate with a water absorption rate of not less than 20% at normal pressure and a particle size of 1-2 mm; Phase change material is adsorbed into the pores of the core by capillary action through the surface pores of the core; a polymer encapsulation layer, located on the surface of the phase change material, forming a flexible film for preventing leakage of the phase change material and acting as a buffer layer when the volume changes due to phase change or temperature change; and A transition layer, coated on the polymer encapsulation layer to reduce the alkalinity of its periphery and prevent alkali corrosion; The shell, covering the transition layer, increases the strength of the artificial lightweight aggregate and reduces water absorption, thereby improving the workability and strength of the concrete or mortar.

[0025] In one embodiment, the artificial lightweight aggregate has a heat capacity of 1100-1200 J / (kg·K), a cylinder compressive strength of 6.0-7.0 MPa, a water absorption rate of less than 7%, and a heat resistance of less than 900 kg / m 3 loose bulk density.

[0026] In one embodiment, the phase change material is selected from polyethylene glycol, lauric acid, or a combination thereof.

[0027] In one embodiment, the polymer encapsulation layer is made of ethylene vinyl acetate copolymer emulsion (EVA emulsion for short).

[0028] In one embodiment, the transition layer is selected from zeolite powder or metakaolin, or a mixture of the two in any proportion.

[0029] In one embodiment, the shell includes cement, silica fume and hydrophilic nano-silica.

[0030] In one embodiment, the transition layer can react with calcium hydroxide in the shell to form calcium silicate hydrate gel.

[0031] In one embodiment, the shell can provide the surface of the artificial lightweight aggregate with chemical reactivity, so that it can react with the cement base to produce calcium hydroxide to form calcium silicate hydrate, thereby strengthening the bonding force between the artificial lightweight aggregate and the cement base.

[0032] To enhance the thermal insulation performance of artificial lightweight aggregate, the present invention utilizes a phase change material to increase the aggregate's heat capacity while maintaining substantially unchanged aggregate density. This helps reduce indoor temperature fluctuations and stabilize indoor temperatures when the aggregate is subsequently incorporated into building structures. Consequently, the present invention provides applications for the artificial lightweight aggregate, such as in construction mortar or concrete.

[0033] According to a second aspect of the present invention, a construction mortar with high heat capacity, high strength and low thermal conductivity is provided, which comprises, by weight, 100-150 parts of cement, 20-40 parts of fly ash, 200-250 parts of river sand, 50-70 parts of water, and 60-100 parts of the artificial lightweight aggregate as described above, the total of which is 450-470 parts.

[0034] In one embodiment, the mortar has a 28-day compressive strength of 40-50 MPa, a heat capacity of 1100-1200 J / (kg·K) and a thermal conductivity of 0.4-0.5 W / (m·K) at a temperature of 35-45° C.

[0035] According to a third aspect of the present invention, there is provided a building concrete having high heat capacity, high strength and low thermal conductivity, comprising, by weight, 300-350 parts of cement, 150-200 parts of fly ash, 50-60 parts of silica fume, 360-400 parts of shale aggregate with a density grade of 500 and a particle size of 5-15 mm, 160-200 parts of shale aggregate with a density grade of 700 and a particle size of 0-5 mm, 160-180 parts of water, 8-12 parts of an admixture, and 200-240 parts of the artificial lightweight aggregate as described above, the total of which is 1480-1540 parts.

[0036] In one embodiment, the mortar has a 28-day compressive strength of 45-55 MPa, a heat capacity of 1000-1100 J / (kg·K) and a thermal conductivity of 0.2-0.4 W / (m·K) at a temperature of 35-45° C.

[0037] According to a fourth aspect of the present invention, there is provided a method for preparing an artificial lightweight aggregate having high heat capacity, high strength, low water absorption and surface reactivity, comprising: Heat the core and phase change material to 100-110°C and 60-70°C respectively; Evenly mixing the core and the phase change material so that the phase change material is adsorbed into the surface pores of the core, and then cooling the core to room temperature; It is uniformly mixed with ethylene and vinyl acetate copolymer emulsion and placed in an environment with a temperature of 20-30°C and a humidity of 50-80% for 120-180 minutes to form a polymer encapsulation layer; Zeolite powder or metakaolin is added and adsorbed on the polymer encapsulation layer to form a transition layer. The zeolite powder or metakaolin is then added to a granulator with cement, silica fume, hydrophilic nano-silica, and water for granulation to form a shell on the transition layer to obtain artificial lightweight aggregate.

[0038] In one embodiment, the method further comprises curing the artificial lightweight aggregate with steam at 60-80° C. and 1 atmosphere of pressure for 24 hours.

[0039] It is worth noting that only steam curing is required in an air environment, and carbonization is not required, because once the degree of carbonization is too high, the alkalinity of the shell will decrease, and the unreacted silica fume in the shell will significantly reduce the reaction activity.

[0040] As used herein, the term "granulation" refers to the preparation of artificial aggregates by granulation or spheroidization. Granulation or spheroidization is a process of agglomerating raw material particles into larger, incompletely hardened particles. A granulator is an instrument commonly used to carry out the granulation or spheroidization process. There are different types of granulators available for purchase on the market, and any type of granulator can be used to prepare the artificial aggregate of the present invention. The granulation capacity of different types of granulators and the size and shape of the produced particles are different. For example, the particles produced by the common disc granulator have a better spherical shape. In view of the better stacking properties and mechanical properties of spherical aggregates, many applications tend to use spherical aggregates, such as making concrete. Therefore, in an embodiment of the present invention, preferably, a disc granulator is used to prepare the artificial aggregate of the present invention.

[0041] Example

[0042] Example 1: Artificial lightweight aggregate with high heat capacity, high strength, low water absorption and surface reactivity

[0043] See also Figure 1, showing an artificial lightweight aggregate 10 with high heat capacity, high strength, low water absorption, and surface reactivity according to one embodiment of the present invention. The core 101 of artificial lightweight aggregate 10 is a porous shale lightweight aggregate, which serves as a carrier for the phase change material and provides a certain strength to the mortar or concrete. Through the capillary action of the pores on the surface of core 101, the phase change material is adsorbed into the pores, forming pores 102 filled with the phase change material. The phase change material absorbs or releases heat during its phase change from solid to liquid (or liquid to solid), increasing the aggregate's heat capacity and stabilizing the temperature of nearby aggregates.

[0044] Next, a polymer encapsulation layer 103 is formed on the surface of the aggregate core. Polymer encapsulation layer 103 is a flexible encapsulation layer, forming a thin, flexible film on the aggregate surface that minimizes surface pores, acting as a primary barrier to prevent leakage of the phase change material. Furthermore, due to its toughness, the polymer encapsulation layer mitigates the impact of the phase change material's volume changes during phase transitions and temperature changes on the rigid outer shell, preventing the aggregate from expanding or cracking. Polymer encapsulation layer 103 is coated with a transition layer 104, primarily composed of amorphous silica-alumina and layered particles of zeolite powder or metakaolin. This transition layer reduces the alkalinity of the polymer encapsulation layer's surface, thereby minimizing alkali corrosion.

[0045] Finally, the outermost layer, the shell 105, is located on the transition layer 104. The shell 105 can provide strength to the artificial lightweight aggregate 10, prevent leakage of the phase change material, and reduce the water absorption rate of the artificial lightweight aggregate 10, so that it will not have a serious negative impact on the subsequent working performance of the mortar or concrete. In addition, because the shell 105 contains silica fume, it has pozzolanic activity and reacts with the calcium hydroxide produced by cement hydration to form a hydrated calcium silicate gel, thereby enhancing the bonding force between the artificial lightweight aggregate 10 and the cement matrix and improving the strength of the mortar or concrete.

[0046] It is worth noting that the zeolite powder or metakaolin in the transition layer 104 reacts with the calcium hydroxide produced by the hydration of cement in the outer shell 105 to form a hydrated calcium silicate gel. Physically, this can fill the gap between the polymer encapsulation layer 103 and the outer shell 105 to improve the strength of the aggregate. Chemically, it can reduce the alkalinity near the polymer encapsulation layer 103 and reduce the corrosion of the polymer by alkali. Although the polymer encapsulation layer 103 itself has strong alkali resistance, if the concentration of alkali near it can be reduced as much as possible, the durability of the polymer encapsulation layer 103 can be further improved.

[0047] Example 2: Preparation of artificial lightweight aggregate with high heat capacity, high strength, low water absorption and surface reactivity

[0048] According to one embodiment of the present invention, the preparation method involves first heating the core material, shale lightweight aggregate, to 100-110°C. Polyethylene glycol and lauric acid are then mixed and heated to 60-70°C to melt them, thereby forming a phase change material. The mixture is then added to a mixer and mixed thoroughly. The capillary action of the shale allows the polyethylene glycol-lauric acid eutectic to be absorbed into the pores of the shale.

[0049] After the shale lightweight aggregate adsorbed with phase change material is cooled to room temperature, it is evenly mixed with an EVA emulsion with a concentration of 55% to form a polymer encapsulation layer on its surface. The aggregate is placed in an environment with a temperature of 20-30°C and a humidity of 50-80% for 120-180 minutes. Within the time period of 120-180 minutes, zeolite powder or metakaolin is added and mixed evenly. At this time, since the EVA emulsion has just entered the demulsification stage and has strong viscosity, it is more conducive to the adsorption of zeolite powder or metakaolin on the surface of the polymer encapsulation layer to form a transition layer.

[0050] After the transition layer is formed, it is granulated with cement, silica fume, hydrophilic nano-silica, and water in a granulator to form a shell on the surface of the particles. Finally, it is cured with steam at 60-80°C and 1 atmosphere of pressure for 24 hours and then cooled to room temperature to obtain an artificial lightweight aggregate with high heat capacity, high strength, low water absorption, and surface reactivity according to one embodiment of the present invention.

[0051] It's worth noting that the outer shell primarily provides strength through cement. The average particle size of silica fume is approximately 1 / 30 of that of cement, filling the gaps between the cement and the outer shell. The average particle size of hydrophilic nano-silica is approximately 1 / 5 of that of silica fume, filling the gaps within the silica fume. This provides a sufficiently dense outer shell to prevent leakage of the phase change material and reduce the water absorption of the aggregate, preventing a serious negative impact on the performance of the mortar or concrete. Furthermore, the presence of silica fume and nano-silica in the outer shell imparts chemical reactivity to the aggregate surface, reacting with the calcium hydroxide produced by cement hydration to form a hydrated calcium silicate gel. This strengthens the bond between the aggregate and the cement matrix, thereby increasing the strength of the mortar or concrete.

[0052] Example 3: Preparation of building mortar with high heat capacity, high strength and low thermal conductivity

[0053] According to the method specified in JGJ98-2010 "Design Code for Mix Ratio of Masonry Mortar", the design strength grade M20 mortar has a mix ratio of cement 360kg / m 3 , river sand 480kg / m 3 , the aggregate of the present invention is 480kg / m 3 , water 300kg / m 3During production, all materials are put into the mortar mixer at the same time and stirred for 180 to 240 seconds to obtain a building mortar with high heat capacity, high strength and low thermal conductivity. Its performance indicators are as follows: 28-day standard curing strength 23.4MPa, 28-day air-dry density 1560kg / m 3 ,

[0054] Example 4: Preparation of high heat capacity, high strength, and low thermal conductivity building concrete

[0055] According to the method specified in JGJ / T12-2019, "Technical Standard for the Application of Lightweight Aggregate Concrete," the mix ratio for concrete with a design strength grade of LC35 is, by weight, 320 parts cement, 175 parts fly ash, 55 parts silica fume, 380 kg of shale aggregate with a density grade of 500 and a particle size of 5-15 mm, 180 kg of shale aggregate with a density grade of 700 and a particle size of 0-5 mm, 170 kg of water, 10 kg of admixture, and 220 kg of the aforementioned artificial lightweight aggregate. To prepare the concrete, first place all solid materials into a forced concrete mixer and mix for 30-60 seconds. Then, add water and admixtures simultaneously and continue mixing for 240-300 seconds, resulting in a construction concrete with high heat capacity, high strength, and low thermal conductivity.

[0056] Example 5: Testing the Temperature Stability and Water Absorption of Artificial Lightweight Aggregates with High Heat Capacity, High Strength, Low Water Absorption, and Surface Reactivity

[0057] River sand, ordinary shale, and an artificial lightweight aggregate with high heat capacity, high strength, low water absorption, and surface reactivity according to one embodiment of the present invention were heated to above 80°C and then placed in a loosely stacked state in a 1L steel cylinder. Since the thermal conductivity of steel is much higher than that of various natural or artificial aggregates, the effect of thermal conductivity on temperature can be minimized. The effect of heat capacity on aggregate temperature and the density of the loosely stacked aggregate were examined.

[0058] like Figure 2 As shown, when the aggregates are in the same loose stacking state, the porosity is roughly the same. The cooling rate of the aggregate of the present invention is significantly slower than that of the river sand, and a slower temperature drop trend is achieved at a lower stacking density.

[0059] Furthermore, as shown in Table 1, the loose bulk density of the aggregate of the present invention is 63% of that of river sand and 105% of that of shale, significantly lower than river sand and only slightly higher than shale. These experimental results demonstrate that the aggregate of the present invention has the characteristics of high heat capacity and light weight.

[0060] Table 1. Loose bulk density river sand 0-5mm shale Artificial lightweight aggregate of the present invention <![CDATA[1460kg / m 3 ]]> <![CDATA[740kg / m 3 ]]> <![CDATA[820kg / m 3 ]]>

[0061] Water absorption was tested according to the method specified in Section 11, "Water Absorption," of GB 17431.2-1998, "Lightweight Aggregates and Their Tests, Part 2: Test Methods for Lightweight Aggregates." The results, shown in Table 2, indicate that because the artificial lightweight aggregate of the present invention is based on shale as its core, its outermost cementitious shell is very dense after being wrapped in a multi-layer structure, resulting in a significantly lower water absorption rate than shale particles.

[0062] Table 2. Water absorption test results Normal pressure, 20±2℃ time 0-5mm river sand 0-5mm shale Artificial lightweight aggregate of the present invention 1h 2.6％ 18.0％ 4.5％ 24h 3.4％ 23.0％ 5.7％

[0063] Example 6: Testing and comparing the strength and temperature changes of high heat capacity, high strength, and low thermal conductivity building mortar

[0064] The strength test of building mortar was carried out according to the method specified in Section 9 "Cube Compressive Strength Test" of JGJ / T 70-2009 "Standard for Test Methods of Basic Properties of Building Mortar". The results are shown in Table 3. The strength of the mortar (Sample 1) incorporating the artificial lightweight aggregate of the present invention is slightly higher than that of ordinary shale mortar (Control 2). The density of the mortar using the artificial lightweight aggregate of the present invention is 72% (1520 / 2120 g / L) of the ordinary mortar (Control 1), while the strength can reach 87% (46 / 52.6 MPa) of the ordinary mortar (Control 1). However, its density is basically the same as that of ordinary shale mortar (Control 2). In other words, the mortar incorporating the artificial lightweight aggregate of the present invention does not affect its strength and density, and there is no significant difference from ordinary shale mortar, thus solving the problem of mortar strength reduction caused by the incorporation of phase change materials.

[0065] Table 3 Composition and strength of control group mortar and samples Mortar strength test mix ratio and strength (g / L)

[0066] Temperature changes can be detected using two methods. One is to create holes in the mortar during its formation. After the mortar hardens, oil is injected into the holes and a kerosene thermometer is inserted into the holes to measure the mortar temperature. The second method is to embed a thermocouple in the mortar during its formation. When temperature measurement is required, the thermocouple is connected to a thermometer and the mortar temperature is recorded using the thermometer.

[0067] The results are as follows Figure 3 As shown, compared with ordinary mortar (control 1) and shale mortar (control 2), the temperature drop curve of the mortar (sample 1) mixed with the artificial lightweight aggregate of the present invention is relatively gentle, especially at 30-40 minutes, compared with controls 1-2, it can maintain a temperature difference of about 5°C higher, indicating that its thermal conductivity is lower.

[0068] As used herein, the terms "approximately," "substantially," "essentially," and "about" are used to describe and explain small variations. When used in conjunction with an event or circumstance, the term can refer to situations where the event or circumstance occurs exactly, as well as situations where the event or circumstance occurs approximately. As used herein with respect to a given value or range, the term "approximately" generally refers to within ±10%, ±5%, ±1%, or ±0.5% of a given value or region. The range can be indicated herein as from one endpoint to another or between two endpoints. Unless otherwise specified, all ranges disclosed herein include endpoints. When referring to a value or characteristic that is "substantially" the same, the term can refer to a value within ±10%, ±5%, ±1%, or ±0.5% of the average of the values.

[0069] The foregoing description has been presented for purposes of illustration and description of the present invention, but is not intended to be exhaustive or to limit the invention to the precise form disclosed, as many modifications and variations will be apparent to those skilled in the art.

[0070] The embodiment was chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated.

Claims

1. An artificial lightweight aggregate having high heat capacity, high strength, low water absorption and surface reactivity, characterized in that: include: The inner core is selected from shale lightweight aggregate with a water absorption rate of not less than 20% at normal pressure and a particle size of 1-2 mm; A phase change material, wherein the phase change material is adsorbed into the pores of the core through capillary action of the surface pores of the core; A polymer encapsulation layer, which is used to form a flexible film on the surface of the core having the phase change material adsorbed thereon to prevent leakage of the phase change material and to serve as a buffer layer when the phase change material undergoes phase change or volume change due to temperature change; A transition layer, the transition layer being coated on the polymer encapsulation layer to reduce the alkalinity of the periphery thereof and prevent it from being corroded by alkali; as well as The shell is coated on the transition layer to improve the strength of the artificial lightweight aggregate and reduce the water absorption rate of the artificial lightweight aggregate, thereby improving the working performance and strength of the concrete or mortar using the artificial lightweight aggregate; wherein the artificial lightweight aggregate has a heat capacity of 1100-1200 J / (kg·K), a cylinder compressive strength of 6.0-7.0 MPa, a water absorption rate of less than 7%, and a load of less than 900 kg / m 3 loose bulk density. 2 . The artificial lightweight aggregate according to claim 1 , wherein the phase change material is selected from polyethylene glycol, lauric acid or a combination thereof.

3. The artificial lightweight aggregate according to claim 1, wherein the polymer encapsulation layer is composed of ethylene-vinyl acetate copolymer emulsion.

4. The artificial lightweight aggregate according to claim 1, wherein the transition layer is selected from zeolite powder or metakaolin, or a mixture thereof in any proportion.

5. The artificial lightweight aggregate according to claim 1, wherein the shell comprises cement, silica fume and hydrophilic nano-dioxide. Silicon oxide.

6. The artificial lightweight aggregate according to claim 1, wherein the transition layer can react with the calcium hydroxide in the shell to generate calcium silicate hydrate gel.

7. The artificial lightweight aggregate according to claim 1, wherein the shell provides a surface of the artificial lightweight aggregate with chemical reactivity, so that the surface of the artificial lightweight aggregate can react with a cement substrate to produce calcium hydroxide to form a calcium silicate hydrate, thereby strengthening the bonding strength between the artificial lightweight aggregate and the cement substrate.

8. A building mortar with high heat capacity, high strength and low thermal conductivity, characterized in that: include: According to weight proportion, the present invention comprises 100-150 parts of cement, 20-40 parts of fly ash, 200-250 parts of river sand, 50-70 parts of water, and 60-100 parts of the artificial lightweight aggregate according to claim 1, the total of which is 450-470 parts.

9. The mortar according to claim 8, wherein the mortar has a 28-day compressive strength of 40-50 MPa, a heat capacity of 1100-1200 J / (kg·K) and a thermal conductivity of 0.4-0.5 W / (m·K) at a temperature of 35-45°C.

10. A high heat capacity, high strength, low thermal conductivity building concrete, characterized in that: include: By weight, the present invention comprises 300-350 parts of cement, 150-200 parts of fly ash, 50-60 parts of silica fume, 360-400 parts of shale aggregate with a density grade of 500 and a particle size of 5-15 mm, 160-200 parts of shale aggregate with a density grade of 700 and a particle size of 0-5 mm, 160-180 parts of water, 8-12 parts of admixture, and 200-240 parts of the artificial lightweight aggregate according to claim 1, the total of which is 1480-1540 parts.

11. The concrete according to claim 10, wherein the concrete has a 28-day compressive strength of 45-55 MPa, a heat capacity of 1000-1100 J / (kg·K) and a thermal conductivity of 0.2-0.4 W / (m·K) at a temperature of 35-45°C.

12. A method for preparing the artificial lightweight aggregate according to claim 1, characterized in that: include: heating the core and the phase change material to 100-110° C. and 60-70° C. respectively; uniformly mixing the core and the phase change material so that the phase change material is adsorbed into the surface pores of the core, and then cooling the core to room temperature; uniformly mixing the mixture with an ethylene-vinyl acetate copolymer emulsion and placing the mixture in an environment with a temperature of 20-30° C. and a humidity of 50-80% for 120-180 minutes to form the polymer encapsulation layer; adding zeolite powder or metakaolin and allowing it to adsorb onto the polymer encapsulation layer to form the transition layer; as well as Then, the mixture is added into a granulator with cement, silica fume, hydrophilic nano-silicon dioxide and water and granulated to form a shell on the transition layer, thereby obtaining the artificial lightweight aggregate.

13. The method according to claim 12, further comprising curing the artificial lightweight aggregate with steam at 60-80°C and 1 atmosphere for 24 hours.

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