High-performance aerated concrete and preparation method thereof

Abstract

The invention discloses high-performance aerated concrete and a preparation method thereof, and solves the problems of long standing time, low early strength, high drying shrinkage value, poor freezing resistance and the like of an existing high-content solid waste-based aerated concrete product. The high-performance aerated concrete disclosed by the invention is prepared from 25 to 28 parts of calcium material, 64.5 to 68.8 parts of siliceous material, 3 to 5 parts of adjusting material and 0.29 to 0.52 part of additive, the mass of the water is calculated according to a water-material ratio of 0.52-0.55. The mechanical property of the aerated concrete is enhanced, and the durability of the aerated concrete in a complex natural environment is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to high-performance aerated concrete and a preparation method thereof. Background Art

[0002] Traditional autoclaved aerated concrete (AAC) is a porous lightweight building material made of fly ash or quartz sand as the main siliceous material, lime and cement as the calcium materials, and then mixed with a gas-generating agent, which is stirred with water to form pores by chemical reaction, and finally cast, pre-cured, cut and autoclaved to produce a porous light building material. In recent years, AAC has been increasingly valued by the building materials industry. As a ready-to-use building material, it has excellent performance characteristics such as light weight, good thermal insulation performance, convenient transportation and convenient construction. In actual engineering applications, AAC is often used as a filling material for building exterior and interior walls, thermal insulation sheets, and load-bearing walls of low-rise building materials.

[0003] At present, due to the scarcity of quartz sand resources and the shortage of fly ash, the production cost of AAC has gradually increased. A large number of studies have verified the potential feasibility of various solid wastes as alternative raw materials for AAC production, including but not limited to high-calcium coal gangue, iron tailings, red mud, molybdenum tailings, circulating fluidized bed fly ash and slag. However, in order to reduce the cost of raw materials, in the process of increasing the proportion of solid waste to replace siliceous materials and reducing the amount of calcium materials at the same time, the following problems arise: the hydration reaction process slows down significantly during the static curing stage, the amount of hydration products generated decreases, and the internal temperature of the body is low. This series of phenomena directly leads to quality problems such as slow hardening rate of aerated concrete body in the pre-curing stage and unsatisfactory early strength. In the processing links such as handling, turning and cutting of the body, undesirable phenomena such as edge shedding, surface scratches and damaged integrity occur. Therefore, the static pre-curing time required for many studies is as long as 12 to 24 hours. Most of these research results can only stay in the laboratory preparation stage and are difficult to be effectively transformed into actual industrial production. In addition, in northern regions, due to the significant temperature difference between day and night and the cold winter climate, high-solid waste-based AAC blocks also face the severe challenge of easy cracking, and improving their anti-freeze performance has become an urgent problem to be solved.

[0004] In summary, there is an urgent need for a method to solve the problems of long static curing time, low early strength and poor frost resistance of high-solid waste-based autoclaved aerated concrete. Summary of the invention

[0005] The object of the present invention is to provide a high-performance aerated concrete and a preparation method thereof, so as to solve the problems of long static time, low early strength, high drying shrinkage value, poor frost resistance, etc. of existing high-content solid waste-based aerated concrete products.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] On the one hand, a high-performance aerated concrete is provided, comprising the following raw materials: a calcareous material, a siliceous material, a regulating material, an admixture and water; the weight proportions of the raw materials are as follows: 25 to 28 parts of calcareous material, 64.5 to 68.8 parts of siliceous material, 3 to 5 parts of regulating material, and 0.29 to 0.52 parts of admixture; the mass of water is calculated based on a water-to-material ratio of 0.52 to 0.55.

[0008] Furthermore, the calcareous material comprises the following substances in percentage by weight: 90-95 wt % of low-carbon cementitious material and 5-10 wt % of fixed-carbon cementitious material.

[0009] Furthermore, the chemical composition of the low-carbon cementitious material includes CaO, and the mineral composition includes the following substances in mass percentage: f-CaO 40-45wt%, C3S22~18wt%, C2S5~15wt%, C4AF 2~5wt%.

[0010] Furthermore, the carbon-fixing cementitious material is a γ-C2S type carbon-fixing cementitious material, and the main mineral phase of the γ-C2S type carbon-fixing cementitious material is γ-C2S.

[0011] Furthermore, the siliceous material comprises the following substances in parts by weight: 64-68 parts of siliceous solid waste and 0.5-0.8 parts of nano-SiO2.

[0012] Furthermore, the siliceous solid waste is one of quartz tailings and coal gasification slag; the SiO2 content of the siliceous solid waste is ≥45wt%, and the 3-day strength activity strength index is ≥75%.

[0013] Furthermore, the regulating material is one or more of desulfurized gypsum, anhydrite and phosphogypsum.

[0014] Furthermore, the admixture includes the following substances in parts by weight: 0.08-0.1 parts of a gas generating agent, 0.01-0.02 parts of a foam stabilizer, 0.1 parts of a water reducing agent, and 0.1-0.3 parts of an antifreeze agent.

[0015] Furthermore, the gas generating agent is aluminum powder, and the active aluminum content is ≥90%; the foam stabilizer is one of sodium dodecylbenzene sulfonate, tea saponin, and calcium stearate; the water reducer is a polycarboxylic acid water reducer; and the antifreeze agent is an ethylene glycol organic antifreeze agent.

[0016] On the other hand, a method for preparing high-performance aerated concrete is provided, comprising the following steps:

[0017] S1. Ingredients: weigh calcium materials, silicon materials, regulating materials, admixtures and water according to their respective masses, heat the water to 50±2℃ and place it in a constant temperature water tank;

[0018] S2, mixing and pouring: the calcareous material, the regulating material and the siliceous material are stirred and mixed to obtain a mixed powder; the water is divided into two parts, one part is mixed and stirred with the gas generating agent and the foam stabilizer of the admixture to form a suspension, and the other part is mixed and stirred with the water reducing agent and the antifreeze agent of the admixture to form a mixed liquid; the mixed liquid is poured into the mixed powder and stirred rapidly for 3 minutes, and then the suspension is added and stirred rapidly for 50 seconds to obtain a slurry; the slurry is injected into the mold;

[0019] S3, static curing: the mold injected with the slurry is moved into a 45°C steam curing box for pre-curing for 2 to 2.5 hours to obtain an embryo body;

[0020] S4, autoclave curing: cutting the expanded surface of the embryo into planes and demoulding, and then putting it into an autoclave for curing at a saturated steam pressure of 1 to 1.2 MPa for 8 hours to obtain high-performance aerated concrete;

[0021] Prior to S1, the particle size distribution of the siliceous solid waste in the siliceous material is regulated: the siliceous solid waste is dried and then ground to a specific surface area of ​​250-360 kg / m 2 , median diameter is 24-37μm;

[0022] In S2, the mass of water mixed with the gas generating agent and the foam stabilizer of the admixture to form the aluminum powder suspension accounts for 12wt% of the total mass of water, and the remaining mass of water is mixed with the water reducing agent and the antifreeze agent of the admixture to form a mixed liquid;

[0023] In S2, a stirring pot is used for stirring; when the mixed powder is poured into the mixed powder and stirred rapidly and the aluminum powder suspension is added and stirred rapidly, the rotational speed of the stirring pot is 285±10r / min and the rotational speed is 125±10r / min.

[0024] The invention adjusts the particle size distribution of the siliceous material, including the specific surface area and the median diameter, so that the siliceous particles at the pore wall are in a tightly packed state, thereby achieving the densification of the pore wall structure of the aerated concrete.

[0025] The present invention adds nano-SiO2 with small particle size and high volcanic ash activity to enable it to undergo secondary hydration reaction with Ca(OH)2 generated by hydration of cementitious materials, while also promoting hydration of low-carbon cementitious materials, improving early strength and reducing static time.

[0026] The present invention can effectively reduce the freezing point of the pore solution of aerated concrete by adding ethylene glycol organic antifreeze agent, thereby improving the antifreeze performance.

[0027] The present invention adds γ-C2S type carbon-fixing cementitious material so that it can be carbonized in the air to generate nano-scale calcium carbonate and silica gel to fill the macroscopic pores and cracks in the concrete, effectively compensating for the strength loss after freeze-thaw cycles.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. Shorten the static time: Add water reducer to improve the fluidity of slurry, improve the gasification effect, and reduce the water-to-material ratio. In addition, by using low-carbon cementitious materials and fixed carbon cementitious materials instead of traditional calcium materials such as quicklime and cement, the f-CaO in the cementitious materials will quickly dissolve during the static process, releasing a large amount of heat, causing the internal temperature of the slurry to rise rapidly; at the same time, minerals such as C3S in the cementitious materials will hydrate to form CSH gel, causing the pore wall strength of the green body to increase rapidly. In addition, a small amount of nano-SiO2 is reasonably added, which has a small particle size and high volcanic ash activity, and can react with Ca(OH)2 generated by the hydration of the cementitious materials for secondary hydration, while promoting the hydration of the cementitious materials and improving the early strength. The above measures can increase the consumption and evaporation rate of free water in the green body, accelerate the hardening of the green body, increase the number of hydration reaction products, and increase the early strength rapidly, thereby further shortening the static maintenance time, improving the turnover efficiency of the mold, and reducing the scrap rate.

[0030] 2. High strength: The compressive strength of concrete is improved by optimizing the pore structure and strengthening the pore walls. The optimization of the pore structure is manifested in the following ways: adding a foam stabilizer can effectively reduce the surface tension of bubbles, inhibit the growth and merging of bubbles, and form closed circular holes with uniform distribution and small pore size. The enhancement of the space wall is manifested in the following ways: by regulating the particle size distribution of the siliceous material, controlling the specific surface area and median diameter of the particles, and a more reasonable particle grading can make the siliceous particles at the pore wall in a tightly packed state, thus achieving the densification of the pore wall structure of the aerated concrete.

[0031] 3. Good frost resistance: Adding a small amount of γ-C2S type carbon-fixing cementitious material is beneficial to improve the frost resistance of aerated concrete. CO2 in the external environment continuously penetrates into the material through the dense pores inside the aerated concrete and dissolves in the pore solution to form CO3 2- Subsequently, γ-C2S reacts with dissolved CO3 2-A chemical reaction occurs to generate nano-scale calcium carbonate and silica gel. These hydration products can effectively fill pores and cracks, promote the close bonding of hydration products between pore walls, and thus enhance the compactness of the aerated concrete structure. Therefore, it also has good mechanical strength and crack resistance in natural environments such as severe cold, large temperature difference between day and night, or high humidity. In addition, the addition of ethylene glycol antifreeze can significantly reduce the freezing point of the pore solution of aerated concrete, ensure that the free water in the pores remains liquid under low temperature conditions, and effectively alleviate the stress accumulation caused by volume changes during the freeze-thaw cycle. This feature is not only beneficial to volume stability, but also promotes the dissolution process of CO2 in the pore solution under low temperature conditions, accelerates the carbonization reaction of γ-C2S, and significantly improves the freeze-thaw resistance of aerated concrete. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] In the embodiment of the present invention, the chemical composition of the low-carbon cementitious material includes CaO, and the mineral composition includes the following substances in percentage by weight: f-CaO 40-45wt%, C3S22~18wt%, C2S5~15wt%, C4AF 2~5wt%.

[0034] In the embodiment of the present invention, the SiO2 content of the siliceous solid waste is ≥45wt%, and the 3-day strength activity strength index is ≥75%.

[0035] Example 1

[0036] As a preferred embodiment of the present invention, the raw material composition of the high performance aerated concrete of this embodiment is shown in Table 1 below.

[0037] Table 1 Composition of high performance aerated concrete components in Example 1

[0038]

[0039] In this embodiment, the quality of water is calculated based on a water-to-material ratio of 0.53.

[0040] The preparation method of high performance aerated concrete in this embodiment is as follows:

[0041] S1. Weigh the calcium material, silicon material, regulating material, admixture and water according to their respective masses, heat the water to 50°C and place it in a constant temperature water tank;

[0042] S2, stirring and mixing the calcareous material, the regulating material and the siliceous material to obtain a mixed powder; dividing the water into two parts, mixing one part with the aluminum powder and the tea saponin to form a suspension, and mixing the other part with the polycarboxylate water reducer and the ethylene glycol organic antifreeze to form a mixed solution; pouring the mixed solution into the mixed powder and stirring rapidly for 3 minutes, then adding the suspension and stirring rapidly for 50 seconds to obtain a slurry; injecting the slurry into a mold;

[0043] S3, moving the mold injected with the slurry into a 45°C steam curing box for pre-curing for 2 hours to promote hydration and evaporate excess water to obtain an embryo with initial strength;

[0044] S4. Cut the expanded surface of the embryo into planes and demould, then put it into an autoclave and cure it at a saturated steam pressure of 1.2 MPa for 8 hours to obtain high-performance aerated concrete.

[0045] Before S1, the particle size distribution of the quartz tailings in the siliceous material was regulated: the quartz tailings were placed in a drying oven at 105°C for 24 hours, and then ground in a SMφ500×500 ball mill, with a loading amount of 5 kg each time, and the grinding media were 60 kg steel balls and 40 kg steel forgings originally provided with the mill, and the grinding time was 30 min, resulting in a specific surface area of ​​320.27 m 2 / kg, quartz tailings sand powder with a median diameter of 28.45μm;

[0046] In S2, the mass of water mixed with the gas generating agent and the foam stabilizer of the admixture to form the aluminum powder suspension accounts for 12wt% of the total mass of water, and the remaining mass of water is mixed with the water reducing agent and the antifreeze agent of the admixture to form a mixed liquid;

[0047] In S2, a stirring pot is used for stirring; when the mixed powder is poured into the mixed powder and stirred rapidly and the aluminum powder suspension is added and stirred rapidly, the rotational speed of the stirring pot is 285±10r / min and the rotational speed is 125±10r / min.

[0048] Example 2

[0049] As a preferred embodiment of the present invention, the raw material composition of the high performance aerated concrete of this embodiment is shown in Table 2 below.

[0050] Table 2 Composition of high performance aerated concrete components in Example 2

[0051]

[0052]

[0053] In this embodiment, the quality of water is calculated based on a water-to-material ratio of 0.52.

[0054] The preparation method of high performance aerated concrete in this embodiment is as follows:

[0055] S1. Weigh the calcium material, silicon material, regulating material, admixture and water according to their respective masses, heat the water to 50°C and place it in a constant temperature water tank;

[0056] S2, stirring and mixing the calcareous material, the regulating material and the siliceous material to obtain a mixed powder; dividing the water into two parts, mixing one part with the aluminum powder and the tea saponin to form a suspension, and mixing the other part with the polycarboxylate water reducer and the ethylene glycol organic antifreeze to form a mixed solution; pouring the mixed solution into the mixed powder and stirring rapidly for 3 minutes, then adding the suspension and stirring rapidly for 50 seconds to obtain a slurry; injecting the slurry into a mold;

[0057] S3, moving the mold injected with the slurry into a 45°C steam curing box for pre-curing for 2 hours to promote hydration and evaporate excess water to obtain an embryo with initial strength;

[0058] S4. Cut the expanded surface of the embryo into planes and demould, then put it into an autoclave and cure it at a saturated steam pressure of 1.2 MPa for 8 hours to obtain high-performance aerated concrete.

[0059] Before S1, the particle size distribution of the coal gasification slag in the siliceous material was regulated: the coal gasification slag was placed in a drying oven at 105°C for 24 hours, and then ground in a SMφ500×500 ball mill. The loading amount was 5 kg each time, and the grinding media were the 60 kg steel balls and 40 kg steel forgings originally provided with the mill. The grinding time was 90 min, and the specific surface area was 356.73 m 2 / kg, coal gasification slag powder with a median diameter of 24.65μm;

[0060] In S2, the mass of water mixed with the gas generating agent and the foam stabilizer of the admixture to form the aluminum powder suspension accounts for 12wt% of the total mass of water, and the remaining mass of water is mixed with the water reducing agent and the antifreeze agent of the admixture to form a mixed liquid;

[0061] In S2, a stirring pot is used for stirring; when the mixed powder is poured into the mixed powder and stirred rapidly and the aluminum powder suspension is added and stirred rapidly, the rotational speed of the stirring pot is 285±10r / min and the rotational speed is 125±10r / min.

[0062] Example 3

[0063] As a preferred embodiment of the present invention, the raw material composition of the high performance aerated concrete of this embodiment is shown in Table 3 below.

[0064] Table 3 Composition of high performance aerated concrete components of Example 3

[0065]

[0066] In this embodiment, the quality of water is calculated based on a water-to-material ratio of 0.53.

[0067] The preparation method of high performance aerated concrete in this embodiment is as follows:

[0068] S1. Weigh the calcium material, silicon material, regulating material, admixture and water according to their respective masses, heat the water to 50°C and place it in a constant temperature water tank;

[0069] S2, stirring and mixing the calcareous material, the regulating material and the siliceous material to obtain a mixed powder; dividing the water into two parts, mixing one part with the aluminum powder and the tea saponin to form a suspension, and mixing the other part with the polycarboxylate water reducer and the ethylene glycol organic antifreeze to form a mixed solution; pouring the mixed solution into the mixed powder and stirring rapidly for 3 minutes, then adding the suspension and stirring rapidly for 50 seconds to obtain a slurry; injecting the slurry into a mold;

[0070] S3, moving the mold injected with the slurry into a 45°C steam curing box for pre-curing for 2 hours to promote hydration and evaporate excess water to obtain an embryo with initial strength;

[0071] S4. Cut the expanded surface of the embryo into planes and demould, then put it into an autoclave and cure it at a saturated steam pressure of 1.2 MPa for 8 hours to obtain high-performance aerated concrete.

[0072] Before S1, the particle size distribution of quartz tailings in the siliceous material was regulated: the coal gasification slag was placed in a drying oven at 105°C for 24 hours, and then ground in a SMφ500×500 ball mill. The loading amount was 5 kg each time, and the grinding media were 60 kg steel balls and 40 kg steel forgings originally provided with the mill. The grinding time was 30 min, and the specific surface area was 320.27 m 2 / kg, quartz tailings sand powder with a median diameter of 28.45μm;

[0073] In S2, the mass of water mixed with the gas generating agent and the foam stabilizer of the admixture to form the aluminum powder suspension accounts for 12wt% of the total mass of water, and the remaining mass of water is mixed with the water reducing agent and the antifreeze agent of the admixture to form a mixed liquid;

[0074] In S2, a stirring pot is used for stirring; when the mixed powder is poured into the mixed powder and stirred rapidly and the aluminum powder suspension is added and stirred rapidly, the rotational speed of the stirring pot is 285±10r / min and the rotational speed is 125±10r / min.

[0075] Example 4

[0076] As a preferred embodiment of the present invention, the raw material composition of the high performance aerated concrete of this embodiment is shown in Table 4 below.

[0077] Table 4 High performance aerated concrete component composition of Example 4

[0078]

[0079] In this embodiment, the quality of water is calculated based on a water-to-material ratio of 0.53.

[0080] The preparation method of high performance aerated concrete in this embodiment is as follows:

[0081] S1. Weigh the calcium material, silicon material, regulating material, admixture and water according to their respective masses, heat the water to 50°C and place it in a constant temperature water tank;

[0082] S2, stirring and mixing the calcareous material, the regulating material and the siliceous material to obtain a mixed powder; dividing the water into two parts, mixing one part with the aluminum powder and the tea saponin to form a suspension, and mixing the other part with the polycarboxylate water reducer and the ethylene glycol organic antifreeze to form a mixed solution; pouring the mixed solution into the mixed powder and stirring rapidly for 3 minutes, then adding the suspension and stirring rapidly for 50 seconds to obtain a slurry; injecting the slurry into a mold;

[0083] S3, moving the mold injected with the slurry into a 45°C steam curing box for pre-curing for 2 hours to promote hydration and evaporate excess water to obtain an embryo with initial strength;

[0084] S4. Cut the expanded surface of the embryo into planes and demould, then put it into an autoclave and cure it at a saturated steam pressure of 1.2 MPa for 8 hours to obtain high-performance aerated concrete.

[0085] Before S1, the particle size distribution of quartz tailings in the siliceous material was regulated: the coal gasification slag was placed in a drying oven at 105°C for 24 hours, and then ground in a SMφ500×500 ball mill. The loading amount was 5 kg each time, and the grinding media were 60 kg steel balls and 40 kg steel forgings originally provided with the mill. The grinding time was 30 min, and the specific surface area was 320.27 m 2 / kg, quartz tailings sand powder with a median diameter of 28.45μm;

[0086] In S2, the mass of water mixed with the gas generating agent and the foam stabilizer of the admixture to form the aluminum powder suspension accounts for 12wt% of the total mass of water, and the remaining mass of water is mixed with the water reducing agent and the antifreeze agent of the admixture to form a mixed liquid;

[0087] In S2, a stirring pot is used for stirring; when the mixed powder is poured into the mixed powder and stirred rapidly and the aluminum powder suspension is added and stirred rapidly, the rotational speed of the stirring pot is 285±10r / min and the rotational speed is 125±10r / min.

[0088] Comparative Example 1

[0089] The aerated concrete of this comparative example has the same raw material composition and preparation method as those of Example 1, except that all the calcareous materials are low-carbon cementitious materials (25 parts, i.e., no γ-C2S type carbon-fixing cementitious materials) and no ethylene glycol organic antifreeze agent.

[0090] Comparative Example 2

[0091] The aerated concrete of this comparative example does not contain nano-SiO2, and the rest of the raw material composition and preparation method are the same as those of Example 3.

[0092] Test Case

[0093] The aerated concrete of each embodiment and comparative example was subjected to performance tests, including the test of dry density and compressive strength after leaving the autoclave, and the dry density, compressive strength, drying shrinkage value and frost resistance of the aerated concrete were tested after 28 days in an open air environment in a severe cold region, wherein the frost resistance was measured by the strength loss and mass loss after 15 freeze-thaw cycles. The performance test results are shown in Table 5.

[0094] Table 5 Aerated concrete performance test results

[0095]

[0096] Analysis of the results in Table 5 shows that the aerated concrete blocks prepared by the present invention show significant advantages. The test results show that under the ratio containing a high proportion of siliceous solid waste, the product has the advantages of rapid improvement of early strength and shortened static period. Specifically, the dry density index of the aerated concrete in each embodiment meets the B06 grade requirements, and its compressive strength is about 16 to 24% higher than the standard value of the A3.5 grade aerated concrete block in GB / T11968-2020. The improvement of the out-of-kettle strength can be attributed to the synergistic mechanism of nano-SiO2: on the one hand, the nano-SiO2 particles consume Ca(OH)2 in the system through secondary hydration reaction, promote the hydration process of low-carbon cementitious materials, and are conducive to the improvement of early strength; on the other hand, its nucleation effect accelerates the formation of CSH gel and tobermorite, thereby forming a densified matrix structure, further promoting the significant improvement of the early strength of the green body and the out-of-kettle strength, so that the static time can be shortened to 2 / 3 of the conventional process. In addition, by controlling the particle size of the siliceous raw material, the siliceous particles at the pore wall are tightly packed, thereby achieving the densification of the pore wall structure of the aerated concrete. The addition of the foam stabilizer is conducive to the formation of closed circular holes with uniform distribution and small pore size, thereby optimizing the pore structure. Therefore, the aerated concrete block of the present invention has excellent physical and mechanical properties and good frost resistance.

[0097] In terms of adaptability to low temperature environments, after being exposed to cold weather for 28 days, the strength loss rate of the embodiment group was ≤11% and the dry density increased. This indicates that during this period, the γ-C2S in the cementitious material carbonized, resulting in the formation of calcium carbonate, which not only increased the mass of the test block but also effectively compensated for the strength loss. The excellent frost resistance of the embodiment group is mainly due to the synergistic effect of the γ-C2S type carbon-fixing cementitious material and the antifreeze agent: the former consumes the dissolved CO3 in the pore solution through the carbonization reaction. 2- The latter inhibits the growth of ice crystals by forming a hydrogen bond network. The dual effects enable free water to remain liquid in a low-temperature environment, significantly increasing the CO2 dissolution rate, thereby accelerating the γ-C2S carbonization reaction, forming a continuously distributed calcium carbonate network structure, and effectively buffering freeze-thaw stress.

[0098] In Comparative Example 1, no γ-C2S type carbon-fixing cementitious material and antifreeze agent were added, which had no adverse effect on the early strength. However, after being exposed to the cold environment for 28 days, obvious structural degradation occurred, and its strength loss rate was as high as 21%. In addition, in Comparative Example 2, no nano-SiO2 was added. Under the same static stop time, the blank hardened more slowly, and slag fell when moved, indicating that the strength before entering the autoclave was low, and its internal structure was easily damaged during the autoclave process, so the strength out of the autoclave was also low; but the decline in the later strength was lower than that of Comparative Example 1, and its antifreeze property was better.

[0099] Finally, it should be noted that the above embodiments are only preferred embodiments of the present invention to illustrate the technical solutions of the present invention, rather than limiting them, and certainly not limiting the patent scope of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. In other words, any changes or modifications made to the main design concept and spirit of the present invention that have no substantive significance, and the technical problems they solve are still consistent with the present invention, should be included in the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention in other related technical fields is also included in the patent protection scope of the present invention.

Claims

1. A high performance aerated concrete, characterized in that: The invention comprises the following raw materials: calcareous material, siliceous material, regulating material, additive and water; the weight proportions of the raw materials are as follows: 25-28 parts of calcareous material, 64.5-68.8 parts of siliceous material, 3-5 parts of regulating material and 0.29-0.52 parts of additive; the mass of water is calculated based on a water-to-material ratio of 0.52-0.

55.

2. A high performance aerated concrete according to claim 1, characterized in that: The calcareous material comprises the following substances in percentage by weight: 90-95 wt % of low-carbon cementitious material and 5-10 wt % of fixed-carbon cementitious material.

3. A high performance aerated concrete according to claim 2, characterized in that: The chemical composition of the low-carbon cementitious material includes CaO, and the mineral composition includes the following substances in percentage by weight: f-CaO 40-45wt%, C3S22~18wt%, C2S 5~15wt%, C4AF 2~5wt%.

4. A high performance aerated concrete according to claim 2, characterized in that: The carbon-fixing cementitious material is a γ-C2S type carbon-fixing cementitious material.

5. The high performance aerated concrete according to claim 1, characterized in that: The siliceous material comprises the following substances in parts by weight: 64-68 parts of siliceous solid waste and 0.5-0.8 parts of nano-SiO2.

6. A high performance aerated concrete according to claim 5, characterized in that: The siliceous solid waste is one of quartz tailings and coal gasification slag; the SiO2 content of the siliceous solid waste is ≥45wt%, and the 3-day strength activity strength index is ≥75%.

7. The high performance aerated concrete according to claim 1, characterized in that: The regulating material is one or more of desulfurized gypsum, anhydrite and phosphogypsum.

8. The high performance aerated concrete according to claim 1, characterized in that: The admixture includes the following substances in parts by weight: 0.08-0.1 parts of a gas generating agent, 0.01-0.02 parts of a foam stabilizer, 0.1 parts of a water reducing agent, and 0.1-0.3 parts of an antifreeze agent.

9. The high performance aerated concrete according to claim 8, characterized in that: The gas generating agent is aluminum powder, and the active aluminum content is ≥90%; the foam stabilizer is one of sodium dodecylbenzene sulfonate, tea saponin, and calcium stearate; the water reducer is a polycarboxylic acid water reducer; and the antifreeze agent is an ethylene glycol organic antifreeze agent.

10. A method for preparing high performance aerated concrete according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Weigh the calcium material, silicon material, regulating material, admixture and water according to their respective masses, heat the water to 50±2℃ and place it in a constant temperature water tank; S2. Stir and mix the calcareous material, the regulating material and the siliceous material to obtain a mixed powder; divide the water into two parts, one part is mixed and stirred with the gas generating agent and the foam stabilizer of the admixture to form an aluminum powder suspension, and the other part is mixed and stirred with the water reducing agent and the antifreeze agent of the admixture to form a mixed liquid; pour the mixed liquid into the mixed powder and stir rapidly for 3 minutes, then add the aluminum powder suspension and stir rapidly for 50 seconds to obtain a slurry; inject the slurry into a mold; S3, moving the mold injected with the slurry into a 45° C. steam curing box for pre-curing for 2 to 2.5 hours to obtain an embryo body; S4, cutting the expanded surface of the embryo into a plane and demoulding it, and then putting it into an autoclave for curing at a saturated steam pressure of 1 to 1.2 MPa for 8 hours to obtain high-performance aerated concrete; Prior to S1, the particle size distribution of the siliceous solid waste in the siliceous material is regulated: the siliceous solid waste is dried and then ground to a specific surface area of ​​250-360 kg / m 2 , median diameter is 24-37μm; In S2, the mass of water mixed with the gas generating agent and the foam stabilizer of the admixture to form the aluminum powder suspension accounts for 12wt% of the total mass of water, and the remaining mass of water is mixed with the water reducing agent and the antifreeze agent of the admixture to form a mixed liquid; In S2, a stirring pot is used for stirring; when the mixed powder is poured into the mixed powder and stirred rapidly and the aluminum powder suspension is added and stirred rapidly, the rotational speed of the stirring pot is 285±10r / min and the rotational speed is 125±10r / min.

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