CN114249561A - Geopolymer foamed cement heat-insulating material and preparation method thereof - Google Patents
Geopolymer foamed cement heat-insulating material and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a geopolymer foamed cement heat-insulating material and a preparation method thereof, wherein the raw materials comprise 100 parts of municipal solid waste incineration bottom ash, 30-80 parts of silicon-rich aluminum raw material, 5-25 parts of magnesium ingredient, 35-70 parts of liquid alkali activator, 0.5-2 parts of thickener and 0.5-3 parts of foam stabilizer. Mixing the raw materials to obtain geopolymer slurry, and performing hydrothermal curing to obtain the geopolymer foamed cement heat-insulating material. The MSWI bottom ash is used as a substrate, so that the harmless treatment and high-valued resource utilization of the MSWI bottom ash are realized, the preparation method is easy to operate, the MSWI bottom ash can be directly used, the pretreatment is not needed, the chemical foaming can be realized without additionally adding a foaming agent, and the material production cost is effectively saved. The obtained foamed cement thermal insulation material has excellent performance, the doped magnesium ingredient can effectively inhibit the phenomena of alkaline infiltration and weathering, and the heavy metal ions are filtered out to meet the limit value requirement of the solid waste leaching toxicity identification standard.
Description
Technical Field
The invention belongs to preparation of building materials, and particularly relates to a geopolymer foamed cement heat-insulating material prepared from waste incineration bottom ash.
Background
The geopolymer is an alkali-activated cementing material prepared by reacting active silica-alumina raw materials (calcined clay, granulated blast furnace slag, fly ash and the like) with a strong-alkaline activator (sodium hydroxide, water glass and the like). The bottom ash of Municipal Solid Waste Incineration (MSWI) is rich in silicon, calcium and aluminum components, the MSWI bottom ash is used as a main raw material, a strong alkaline excitant is added, the alkali foaming characteristic of the bottom ash can be fully exerted, and the foaming cement with excellent heat insulation performance can be prepared by matching a foam stabilizer and a hydrothermal curing system. Meanwhile, the specific three-dimensional network structure of the geopolymer is also beneficial to solidifying heavy metal elements contained in the bottom ash, and the harmless treatment and high-value utilization of the bottom ash are realized.
However, due to the use of the strong alkaline excitant, the loose and porous geopolymer foamed cement product is easy to have the phenomena of alkaline efflorescence, namely, the seeped strong alkaline pore solution rich in sodium ions reacts with carbonate ions in the air to generate a sodium carbonate crystallization product, and the reaction process is that
Alkali loss and expansion stress of the crystallized product can destroy the structural stability of the geopolymer hardened body, ultimately affecting the strength and thermal insulation properties of the foamed cement. Therefore, how to effectively inhibit the alkaline-penetrating weathering phenomenon of geopolymer foamed cement also becomes a main technical problem to be solved urgently for such products.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a geopolymer foam cement heat-insulating material which inhibits the effect of alkaline-penetrating weathering and takes MSWI bottom ash as a foam raw material; the second purpose of the invention is to provide a preparation method of the geopolymer foam cement thermal insulation material.
The technical scheme is as follows: the invention relates to a geopolymer foam cement heat-insulating material which is composed of the following materials in parts by weight:
further, the magnesium ingredient comprises any one or more of magnesium oxide, magnesium chloride, magnesium nitrate and magnesium sulfate. The magnesium ingredient is contacted with the strong alkaline excitant to dissolve out magnesium ions, and the magnesium ingredient reacts with carbonate ions in the air to generate magnesium carbonate crystallization precipitation products, the solubility of the magnesium carbonate crystallization precipitation products is far lower than that of sodium carbonate crystals, so that pores can be effectively filled and alkali permeation channels can be blocked, and the alkali permeation weathering is inhibited. Meanwhile, the active magnesium component reacts with the aluminum component dissolved out from the silicon-rich aluminum raw material to generate a hydrotalcite-like mineral phase with a layered Mg-Al double metal hydroxide structure in the geopolymer, so that heavy metal elements such As As, Ba, Cr, Cu, Hg and Pb in the MSWI bottom ash can be adsorbed and solidified, and the use safety of the geopolymer foamed cement heat-insulating material is further improved.
Further, the silicon-rich aluminum raw material comprises one or more of metakaolin, granulated blast furnace slag, fly ash, steel slag and rice hull ash. Wherein, the metakaolin is aluminosilicate mineral phase formed by high-temperature calcination of the kaolin; when the granulated blast furnace slag is pig iron smelted by a blast furnace, the melt is quenched to form an industrial byproduct rich in calcium aluminosilicate vitreous body; the fly ash is fly ash collected from coal-fired flue gas; the steel slag is the waste slag which is generated in the steel smelting process and is rich in crystalline phase and vitreous body; the rice hull ash is ash obtained by burning rice hulls. The silicon-rich aluminum raw material supplements silicon, aluminum and certain calcium components for MSWI bottom ash, improves the activity of the raw material, and promotes alkali-activated reaction, so as to prepare the geopolymer foamed cement with stable structure, high strength and excellent performance.
Further, the liquid alkali activator is prepared by water, sodium hydroxide and water glass; SiO in liquid excitant2And Na2The molar ratio of the O component is 1.4-2.0: 1, SiO2And Na2The solid content of O is 25-35%.The strong alkaline environment provided by the liquid alkali activator can dissolve the MSWI bottom ash, the silicon-rich aluminum raw material and the magnesium ingredient, so as to initiate alkali excitation reaction and promote the coagulation and hardening of geopolymer slurry. SiO in liquid alkali excitant2The more the content, the more viscous the liquid, which in turn increases the viscosity of the geopolymer slurry. The slurry is too viscous, which is not beneficial to the foaming process of the reaction of the aluminum metal chips in the bottom ash to release hydrogen, and the slurry is too thin, which is poor in foam stability and easy to break.
Further, the thickener includes any one or more of hydroxymethyl cellulose, carboxymethyl cellulose, ethyl cellulose, and hydroxyethyl methyl cellulose. The proper amount of the thickening agent can adjust the viscosity of the slurry, increase the homogeneity and maintain the good stability of the foam, more importantly, the foaming reaction rate of the bottom ash after being subjected to alkali can be effectively controlled, the foaming amount is controlled, the phenomenon that the foam in a local area is concentrated to form a large cavity and the structural integrity of a hardening body is damaged is avoided, and the foam stabilizing effect is achieved.
Further, the foam stabilizer comprises any one or more of polyacrylamide emulsion, silicone polyether emulsion and dodecyl dimethyl amine oxide. The polyacrylamide emulsion can play a role in suspension and thickening in geopolymer slurry, can keep good stability of foam in the hydrothermal curing process, and is insensitive to sodium hydroxide in a strong alkaline activator. The silicone polyether emulsion can improve the structural stability of a bubble liquid film, improve the foam elasticity and the self-repairing capability, and has an obvious foam stabilizing effect. The dodecyl dimethyl amine oxide solution has thickening and foam stabilizing effects in an alkaline medium besides the effect of a common nonionic surfactant.
Furthermore, the mesh number of the waste incineration bottom ash is 60-120 meshes. The MSWI bottom ash is prepared from powdery MSWI bottom ash, the MSWI bottom ash is ground into powder by a ball mill to be used as a main raw material for preparing geopolymer, the particle size of the ball-milled MSWI bottom ash powder is small, the contact area with a strong alkaline liquid excitant is large during alkali excitation reaction, and the reaction activity of the bottom ash is further improved. Wherein the waste incineration bottom ash comprises 32.1-56.6 wt% of SiO27.77-10.4 wt% of Al2O314.47-22.7 wt% of CaO, 2.20-10.17 wt% of Fe2O30 to 2.38 wt% of MgO, 0 to 12.4 wt% of Na2O, 0.8 to 1.77 wt% of K2O and the balance of heavy metal elements. The heavy metal elements include As, Ba, Cr, Cu, Hg, Pb, etc.
The preparation method of the geopolymer foamed cement heat-insulating material comprises the steps of mixing MSWI bottom ash, a silicon-rich aluminum raw material, a magnesium ingredient, a liquid alkali activator, a thickening agent and a foam stabilizer to obtain geopolymer slurry, and performing hydrothermal curing to obtain the geopolymer foamed cement heat-insulating material. Wherein the hydrothermal curing temperature is 40-60 ℃, and the curing time is 48-72 h.
In the components of the heat insulation material, the waste incineration bottom ash, the silicon-rich aluminum raw material and the liquid alkali activator form an alkali-activated foaming system, and the waste incineration bottom ash is completely used as the raw material without adding an additional foaming agent; the magnesium ingredient, the thickening agent and the foam stabilizer form a modified component; the magnesium ions provided by the magnesium ingredient can form magnesium carbonate crystal precipitation to inhibit alkali infiltration weathering, can form hydrotalcite-like mineral phase with a double-metal hydroxide structure to solidify heavy metal elements in bottom ash, and can also react with the silicon-rich aluminum raw material to form a magnesium-aluminum silicate gel phase product to promote the development of the early strength of a hardened body, so that the synergistic effects of simultaneously improving the strength, inhibiting alkali infiltration, solidifying heavy metal ions and the like are achieved by adding the magnesium ingredient. The addition of the thickening agent achieves the function of controlling the foaming reaction rate, the addition of the foam stabilizer achieves the foam stabilizing effect, and the thickening agent and the foam stabilizer jointly promote the homogeneous and stable forming process of the geopolymer foaming cement hardened body in the hydrothermal reaction preparation process
The thermal insulation material is subjected to hydrothermal reaction, and the hydrothermal curing can improve the foaming efficiency and promote the hardening and early strength development of the foaming cement; hydrothermal curing temperature and time are critical to formation, which is largely dependent on the rate of alkali-activated reaction of the geopolymer. The temperature is too high, the alkali-activated reaction rate is too high, so that the cement hardened body is hardened in advance, and the bottom ash cannot be fully foamed; the temperature is too low, the alkali-activated reaction is slow, and the strength of the hardened foamed cement is low and the structural stability is poor.
Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: (1) the MSWI bottom ash is used as the matrix, so that the harmless treatment and high-valued resource utilization of the MSWI bottom ash are realized, and the prepared foamed cement heat-insulating material is low in density, high in strength and excellent in heat-insulating property; the dry bulk density is 200 to 450kg/m3Within the range, the compressive strength is 2.5-4.8 MPa, and the heat conductivity coefficient is 0.100-0.130W/(mk); (2) the magnesium ingredient doped in the geopolymer can be quickly dissolved in the strong alkaline pore solution to form a magnesium-rich environment, so that the continuous contact of the strong alkaline pore solution and carbonate ions in the air is inhibited, and the effect of improving alkaline-penetrating weathering is achieved; the doped magnesium ingredient is easy to react with the active aluminum component in the geopolymer, and is beneficial to solidifying heavy metal elements, so that the heavy metal ions of the foamed cement heat-insulating material are filtered out to meet the limit value requirement of the solid waste leaching toxicity identification standard (GB 5095.3-2007); (3) the preparation method is easy to operate, the MSWI bottom ash can be directly used without pretreatment, the reaction of the aluminum metal fragments remained in the bottom ash and the strong-alkaline exciting agent is fully utilized to release hydrogen, chemical foaming can be realized without adding a foaming agent additionally, and the material production cost is effectively saved.
Drawings
FIG. 1 is a comparison of the alkali bleed on the surface of the samples of example 2, comparative example 1 and comparative example 2.
Detailed Description
The invention is further illustrated by the following figures and examples.
Example 1
And (3) ball-milling the MSWI bottom ash for 5 minutes by a dry method, and sieving to obtain 80-mesh bottom ash. Mixing water, sodium hydroxide and water glass to prepare SiO2：Na2The O molar ratio is 1.4, and the solid content is 25 wt% of liquid alkali activator.
100 parts of MSWI bottom ash, 40 parts of silicon-rich aluminum raw material (comprising 20 parts of fly ash and 20 parts of granulated blast furnace slag), 5 parts of magnesium oxide, 50 parts of liquid alkali activator, 0.5 part of ethyl cellulose and 1 part of polyacrylamide emulsion are uniformly mixed to prepare geopolymer slurry, and the geopolymer slurry is cured at 40 ℃ for 48 hours to prepare the foamed cement heat-insulating material.
Example 2
The MSWI bottom ash is ball-milled for 10 minutes by a dry method and then sieved to obtain 60-mesh bottom ash. Mixing water, sodium hydroxide and water glass to prepare SiO2：Na2The O molar ratio is 1.6, and the solid content is 35 wt% of liquid alkali activator.
Uniformly mixing 100 parts of MSWI bottom ash, 50 parts of fly ash, 10 parts of magnesium ingredient (containing 5 parts of magnesium chloride and 5 parts of magnesium sulfate), 60 parts of liquid alkali activator, 1 part of carboxymethyl cellulose and 2 parts of foam stabilizer (containing 1 part of polyacrylamide emulsion and 1 part of silicone polyether emulsion) to prepare geopolymer slurry, and curing at 40 ℃ for 48 hours to prepare the foamed cement heat-insulating material.
Example 3
And (3) carrying out dry ball milling on the MSWI bottom ash for 15 minutes, and sieving to obtain 100-mesh bottom ash. Mixing water, sodium hydroxide and water glass to prepare SiO2：Na2The O molar ratio is 1.8, and the solid content is 30 wt% of liquid alkali activator.
100 parts of MSWI bottom ash, 80 parts of silicon-rich aluminum raw material (comprising 40 parts of granulated blast furnace slag and 40 parts of steel slag), 15 parts of magnesium ingredient (comprising 5 parts of magnesium oxide and 10 parts of magnesium sulfate), 70 parts of liquid alkali activator, 2 parts of hydroxymethyl cellulose and 1.5 parts of silicone resin polyether emulsion are uniformly mixed to prepare geopolymer slurry, and the geopolymer slurry is cured at 60 ℃ for 72 hours to prepare the foamed cement heat-insulating material.
Example 4
And (3) carrying out dry ball milling on the MSWI bottom ash for 15 minutes, and sieving to obtain 100-mesh bottom ash. Mixing water, sodium hydroxide and water glass to prepare SiO2：Na2The O molar ratio is 2.0, and the solid content is 25 wt% of liquid alkali activator.
100 parts of MSWI bottom ash, 60 parts of silicon-rich aluminum raw material (comprising 20 parts of fly ash, 20 parts of granulated blast furnace slag and 20 parts of metakaolin), 5 parts of magnesium sulfate, 65 parts of liquid alkali activator, 1 part of hydroxyethyl methyl cellulose and 2 parts of foam stabilizer (comprising 1 part of silicone resin polyether emulsion and 1 part of dodecyl dimethyl amine oxide solution) are uniformly mixed to prepare geopolymer slurry, and the geopolymer slurry is cured at 50 ℃ for 48 hours to prepare the foamed cement heat-insulating material.
Comparative example 1
The specific raw material dosage and the preparation process are the same as those in example 2, except that no magnesium ingredient is added in the system.
The preparation process comprises the following steps: uniformly mixing 100 parts of MSWI bottom ash, 50 parts of fly ash, 60 parts of liquid alkali activator, 1 part of carboxymethyl cellulose and 2 parts of foam stabilizer (comprising 1 part of polyacrylamide emulsion and 1 part of silicone polyether emulsion) to prepare geopolymer slurry, and curing at 40 ℃ for 48 hours to prepare the foamed cement heat-insulating material.
Comparative example 2
The specific raw material dosage and preparation process are the same as example 2, except that an excessive magnesium ingredient (30 parts) is added into the system. The 30 parts of magnesium ingredient are 10 parts of magnesium oxide, 10 parts of magnesium nitrate and 10 parts of magnesium sulfate.
The preparation process comprises the following steps: uniformly mixing 100 parts of MSWI bottom ash, 50 parts of fly ash, 30 parts of magnesium ingredient, 60 parts of liquid alkali activator, 1 part of carboxymethyl cellulose and 2 parts of foam stabilizer (comprising 1 part of polyacrylamide emulsion and 1 part of silicone polyether emulsion) to prepare geopolymer slurry, and curing for 48 hours at 40 ℃ to prepare the foamed cement heat-insulating material.
Comparative example 3
The specific raw material amounts and the preparation process are the same as those in example 2, except that no thickener is added to the system.
The preparation process comprises the following steps: uniformly mixing 100 parts of MSWI bottom ash, 50 parts of fly ash, 10 parts of magnesium ingredient (containing 5 parts of magnesium chloride and 5 parts of magnesium sulfate), 60 parts of liquid alkali activator and 2 parts of foam stabilizer (containing 1 part of polyacrylamide emulsion and 1 part of silicone polyether emulsion) to prepare geopolymer slurry, and curing at 40 ℃ for 48 hours to prepare the foamed cement heat-insulating material.
Comparative example 4
The specific raw material dosage and the preparation process are the same as those in example 2, except that no foam stabilizer is added in the system.
The preparation process comprises the following steps: uniformly mixing 100 parts of MSWI bottom ash, 50 parts of fly ash, 10 parts of magnesium ingredient (containing 5 parts of magnesium chloride and 5 parts of magnesium sulfate), 60 parts of liquid alkali activator and 1 part of carboxymethyl cellulose to prepare geopolymer slurry, and curing at 40 ℃ for 48 hours to prepare the foamed cement heat-insulating material.
Referring to fig. 1, the alkali penetration condition of the surface of the foaming cement heat preservation material samples prepared in example 2, comparative example 1 and comparative example 2 is shown; wherein (a) represents a sample of example 2, (b) represents a sample of comparative example 1, and (c) represents a sample of comparative example 2. As can be seen from the figure, the surface of the geopolymer hardened body without the magnesium ingredient is seriously infiltrated with alkali, and the surface is peeled off due to the leaching of efflorescence products and alkali; the hardened geopolymer body with excessive magnesium ingredient has obvious structural cracks, and the magnesium ingredient reacts with hydroxide ions in strong alkaline pore solution to generate a large amount of Mg (OH)2The crystal expansion force of the alkali-permeable hardened body causes the structural damage of the geopolymer, and the generated cracks become alkali-permeable channels, so that the alkali-permeable weathering phenomenon is further accelerated, and the surface alkali-permeable of the hardened body is still serious. Therefore, only the addition of the magnesium ingredient within the limited range can achieve the effect of inhibiting the efflorescence of the alkali penetration, but the excessive magnesium ingredient can generate structural crack propagation and can cause serious alkali penetration.
The dry bulk density, compressive strength and thermal conductivity of the geopolymer foamed cement insulation materials prepared in examples 1-4 and comparative examples 1-4 were measured, respectively, as shown in table 1.
TABLE 1 basic Properties of Geopolymer foamed cement insulation
As can be seen from Table 1, the dry bulk densities of examples 1-4 were 230-400kg/m3In the range of 0.110-0.130W/(m.k), the 7-day compressive strength is in the range of 2.9-4.5MPa, the heat preservation performance is excellent, and the early strength is developed rapidly. Whereas in comparative examples 1-4: the absence of magnesium burden results in a significant decrease in 7 day compressive strength,only reaches 1.2MPa, because the severe alkali-permeable weathering reduces the alkali-activated reaction rate, and simultaneously, weathering products cause the surface of a hardened body to peel off, thereby reducing the compressive strength; the addition of too much magnesium charge resulted in an increase in the thermal conductivity to 0.145W/(m.k) and a decrease in the 7-day compressive strength to 0.8MPa due to the formation of excess Mg (OH)2The crystal expansion force of the material causes the crack of the structure to expand, which not only increases the heat transfer channel of heat flow, but also influences the structural stability of the hardened body; the foaming reaction of bottom ash and an alkali activator is aggravated without adding a thickening agent, a large cavity is formed in a local area in a concentrated manner, the thermal conductivity coefficient is increased to 0.350W/(m.k) due to the uneven foam structure, and the strength is reduced to 1.3 MPa; the absence of foam stabilizers can seriously affect the foaming effect and destroy the foam structure in the hardened body, leading to an increase in the dry bulk density of the geopolymer hardened body to 620kg/m3The thermal conductivity increased to 0.425W/(m.k). Therefore, the addition of a proper amount of magnesium ingredients, a thickening agent and a foam stabilizer is a key technical parameter for preparing the geopolymer foamed cement thermal insulation material with excellent performance by using bottom ash.
The geopolymer foamed cement heat-insulating materials prepared in examples 1-4 and comparative examples 1-2 were tested for leaching heavy metal elements according to the environmental protection industry standard "solid waste leaching toxicity leaching method sulfuric acid-nitric acid method" (HJ/T299-2007), as shown in Table 2.
TABLE 2 heavy metal element leaching of geopolymer foamed cement insulation
As can be seen from Table 2, examples 1 to 4 all meet the limit requirements of the solid waste leaching toxicity identification standard (GB 5095.3-2007), and the prepared geopolymer foamed cement thermal insulation material can be safely used. In comparative example 1, no magnesium ingredient is added, so no hydrotalcite-like mineral phase with a layered Mg-Al double metal hydroxide structure is generated in the geopolymer, and heavy metal elements such As As, Ba, Cr, Cu, Hg and Pb in MSWI bottom ash cannot be effectively adsorbed and solidified, so that the leaching concentration is comprehensiveAnd the As, Ba, Cr and Hg in the cement are all higher than the standard limit value, so that the use safety of the foamed cement is seriously reduced. The magnesium ingredient in comparative example 2 is added in an amount too high to effectively promote the formation of hydrotalcite-like mineral phase, but because of Mg (OH)2The structure is cracked due to the crystal expansion force, so that the hardened body still cannot effectively inhibit the heavy metal elements from being filtered out, exceeds the standard limit value requirement and cannot be safely used.
Example 5
Two sets of parallel tests were designed, and the specific preparation process was the same as that in example 2, except that the hydrothermal curing temperatures were different, namely 25 ℃ and 80 ℃.
The performance of the prepared geopolymer foamed cement thermal insulation material is as follows 3.
TABLE 3 Properties of materials at different curing temperatures
As can be seen from Table 3, different hydrothermal curing temperatures have great influence on the material performance, when the curing temperature is low (25 ℃), the alkali-activated reaction is slow, the strength of the hardened foamed cement is low, and the compressive strength is only 0.5MPa in 7 days; when the curing temperature is high (80 ℃), the alkali-activated reaction rate is too high, so that the cement hardened body is hardened in advance, and the bottom ash cannot be fully foamed, so that the dry bulk density is increased to 560kg/m3The thermal conductivity coefficient is increased to 0.660W/(m.k), so that the thermal insulation performance of the foamed cement is poor.
Claims (10)
1. The geopolymer foam cement heat-insulating material is characterized by comprising the following materials in parts by weight:
2. the geopolymer foamed cement insulation according to claim 1, characterized in that: the magnesium ingredient comprises any one or more of magnesium oxide, magnesium chloride, magnesium nitrate and magnesium sulfate.
3. The geopolymer foamed cement insulation according to claim 1, characterized in that: the silicon-rich aluminum raw material comprises one or more of metakaolin, granulated blast furnace slag, fly ash, steel slag and rice husk ash.
4. The geopolymer foamed cement insulation according to claim 1, characterized in that: the liquid alkali activator is prepared from water, sodium hydroxide and water glass; SiO in liquid excitant2And Na2The molar ratio of the O component is 1.4-2.0: 1, SiO2And Na2The solid content of O is 25-35%.
5. The geopolymer foamed cement insulation according to claim 1, characterized in that: the thickener comprises any one or more of hydroxymethyl cellulose, carboxymethyl cellulose, ethyl cellulose and hydroxyethyl methyl cellulose.
6. The geopolymer foamed cement insulation according to claim 1, characterized in that: the foam stabilizer comprises any one or more of polyacrylamide emulsion, silicone polyether emulsion and dodecyl dimethyl amine oxide.
7. The geopolymer foamed cement insulation according to claim 1, characterized in that: the mesh number of the waste incineration bottom ash is 60-120 meshes.
8. The geopolymer foamed cement insulation material of claim 7, characterized in that: the waste incineration bottom ash comprises 32.1-56.6 wt% of SiO27.77-10.4 wt% of Al2O314.47-22.7 wt% of CaO, 2.20-10.17 wt% of Fe2O30 to 2.38 wt% of MgO, 0 to 12.4 wt% of Na2O, 0.8 to 1.77 wt% of K2O and the balance of heavy metal elements.
9. A method for preparing the geopolymer foamed cement thermal insulation material of claim 1, which is characterized in that: mixing the MSWI bottom ash, the silicon-rich aluminum raw material, the magnesium ingredient, the liquid alkali activator, the thickening agent and the foam stabilizer to obtain geopolymer slurry, and performing hydrothermal curing to obtain the geopolymer foamed cement heat-insulating material.
10. The method for preparing the geopolymer foamed cement thermal insulation material according to claim 9, characterized in that: the hydrothermal curing temperature is 40-60 ℃, and the curing time is 48-72 hours.
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