A method for manufacturing autoclaved brick

Abstract

The application discloses a preparation method of steam pressure bricks, and relates to the technical field of wall materials. The steam pressure bricks are prepared by using aerated concrete waste, titanium-containing blast furnace slag, cementitious material waste and siliceous material, do not need high-temperature calcination and lime mixing, have the advantages of simple process, convenient reaction process control and the like, reduce the dependence on traditional resource consumption, realize the resource utilization of the waste such as the titanium-containing blast furnace slag, low-carbon cementitious material waste and aerated concrete waste, and the like. The mineral composition in the low-carbon cementitious material or low-carbon cementitious material damp waste can make the green body structure stronger after continuous hydration, enhances the ability of the green body to adapt to the temperature difference stress and humidity difference stress during the steam pressure kettle steam curing, and improves the performance of the steam pressure bricks.

Description

Technical Field

[0001] This invention relates to the field of wall material technology, and specifically to a method for preparing autoclaved bricks. Background Technology

[0002] As a new type of green wall material, autoclaved aerated concrete (AAC) is being used more and more widely. On the one hand, due to its relatively low strength, AAC is easily damaged during production or transportation, leading to substandard products. These substandard products are not being fully and effectively utilized. On the other hand, with the rapid development of engineering construction, the amount of waste material from building demolition and construction is constantly increasing. The reuse rate of autoclaved aerated concrete waste after demolition is very low, creating a significant burden of construction waste disposal for the country and society. The mineral and chemical composition of AAC is similar to that of autoclaved lime-sand bricks; therefore, AAC waste can be used as aggregate for autoclaved bricks, siliceous materials for hydration reactions, and crystal guides for hydrothermal synthesis.

[0003] The cementitious bonding properties of titanium-containing blast furnace slag are quite limited. However, due to the unique high-pressure and high-temperature production process of autoclaved bricks, the utilization of titanium-containing blast furnace slag is feasible. Meanwhile, low-carbon cementitious materials for aerated concrete are green and low-carbon materials; however, due to the special production process and their high mineral reactivity, if not consumed in time during aerated concrete production, they easily react with moisture in the air, leading to a decline in material performance. This results in problems such as poor casting stability and long settling times during aerated concrete production. Failure to utilize this portion of low-carbon cementitious material in a timely manner leads to resource waste. The chemical and mineral composition of low-carbon cementitious materials that have been slightly or moderately moistened is suitable as raw materials for autoclaved bricks, which can save resources and improve the performance of autoclaved bricks. Summary of the Invention

[0004] The purpose of this invention is to provide a method for obtaining autoclaved bricks by utilizing waste materials from aerated concrete, industrial waste titanium-containing blast furnace slag, and damp waste materials from low-carbon cementitious materials, through a designed raw material ratio and preparation process. The resulting autoclaved bricks have good performance. This method can provide a solution to the problem of difficult disposal and the utilization of limited titanium-containing blast furnace slag and aerated concrete waste materials.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing autoclaved bricks includes the following steps:

[0007] S1. Mix the aerated concrete waste material, titanium-containing blast furnace slag, cementitious materials, and siliceous materials evenly to obtain a mixed dry material. Add water to the mixed dry material to obtain a mixture.

[0008] S2. Allow the mixture to stand and digest in a natural environment for 4-10 hours to obtain the billet.

[0009] S3. Pour the billet into the brick mold and use a pressure of 20MPa to make the green brick;

[0010] S4. Place the green bricks into an autoclave and steam them at 185℃ and 1.0-1.2MPa for 5-8 hours to obtain autoclaved bricks.

[0011] Furthermore, the mass percentages of the aerated concrete waste, titanium-containing blast furnace slag, cementitious materials, and siliceous materials are 10-15wt%, 12-20wt%, 8-15wt%, and 50-65wt%, respectively, and the amount of water added accounts for 8-14wt% of the mass of the mixed dry materials.

[0012] Furthermore, the proportion of particles with a size of 0-0.08 mm in the aerated concrete waste material is 90-95%.

[0013] Furthermore, the proportions of particles with particle sizes of 0.15-0.3 mm and 0-0.15 mm in the titanium-containing blast furnace slag are 0-30% and 45-75%, respectively.

[0014] Furthermore, the titanium-containing blast furnace slag contains 20-30 wt% CaO, 25-30 wt% SiO2, 5-13 wt% Al2O3, and 5-12 wt% TiO2.

[0015] Furthermore, the cementing material is one or both of low-carbon cementing materials or damp waste of low-carbon cementing materials.

[0016] Preferably, the cementing material is low-carbon cementing material waste.

[0017] Furthermore, the mineral composition of the low-carbon cementitious material is: f-CaO: 24-40wt%, C2S: 30-55wt%. 1-10wt%, C4AF: 0.1-10wt%, CaSO4: 0.1-10wt%.

[0018] Furthermore, the mineral composition of the low-carbon cementitious material wetted waste is: f-CaO: 5-35wt%, C2S: 25-50wt%. 0.1-10wt%, C4AF: 0.1-10wt%, CaSO4: 0.1-10wt%, Ca(OH)2: 1-15wt%.

[0019] Furthermore, the siliceous material is one or more of fly ash, quartz sand, and tailings sand, and the proportions of particles with particle sizes of 0-0.15mm, 0.15-0.3mm, 0.3-0.45mm, 0.45-1.2mm, and 1.2-2.5mm in the siliceous material are 35-50%, 25-35%, 3-7%, 3-7%, and 3-6%, respectively.

[0020] Furthermore, the siliceous material is one or more of fly ash, sand, and tailings sand, and the SiO2 content of the siliceous material is ≥65wt%.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) This invention utilizes aerated concrete waste, titanium-containing blast furnace slag, damp cementitious material waste, and siliceous materials to prepare autoclaved bricks. It does not require high-temperature calcination or the addition of quicklime. It has the advantages of simple process and convenient control of reaction process. It reduces the dependence on traditional resource consumption and realizes the resource utilization of waste materials such as titanium-containing blast furnace slag, damp low-carbon cementitious material waste, and aerated concrete waste.

[0023] (2) The mineral composition of the low-carbon cementitious material or the damp waste of low-carbon cementitious material used in this invention can result in higher structural strength of the green body after continued static hydration. At the same time, the alkalinity of the hydration environment is also higher, which has a certain activating effect on titanium-containing slag, improves the activity of titanium-containing slag, enhances the hydration reaction activity and hydrothermal reaction activity of titanium slag, and enhances the ability of the green body to adapt to temperature and humidity stress during autoclaving. During autoclaving, the gypsum (CaSO4) can promote the hydrothermal reaction, causing CSH(I) to transform into tobermorite; at the same time, it can inhibit the formation of hydrogarnet. The aluminum (Al) in the hydrated minerals of anhydrous calcium sulfoaluminate can also promote the transformation of CSH(I) into tobermorite, while preventing its transformation into calcareous silica, thereby improving the strength of the product and reducing product shrinkage. Attached Figure Description

[0024] Figure 1 This is a microscopic morphology diagram of the autoclaved brick of Embodiment 1 of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0026] In this embodiment of the invention, the amount of water added accounts for 8-14 wt% of the mass of the mixed dry material.

[0027] In the embodiments of the present invention, the proportion of particles with a size of 0-0.08 mm in the aerated concrete waste material is 90-95%.

[0028] The titanium-containing blast furnace slag used in this embodiment of the invention contains 20-30 wt% CaO, 25-30 wt% SiO2, 5-13 wt% Al2O3, and 5-12 wt% TiO2.

[0029] The cementing material used in this invention embodiment is one or both of low-carbon cementing materials or damp waste of low-carbon cementing materials. The mineral composition of the low-carbon cementing material is: f-CaO: 24-40wt%, C2S: 30-55wt%. 1-10wt%, C4AF: 0.1-10wt%, CaSO4: 0.1-10wt%. The mineral composition of damp waste low-carbon cementitious materials is: f-CaO: 5-35wt%, C2S: 25-50wt%. 0.1-10wt%, C4AF: 0.1-10wt%, CaSO4: 0.1-10wt%, Ca(OH)2: 1-15wt%.

[0030] The siliceous material used in this invention embodiment is one or more of fly ash, quartz sand, and tailings sand. The proportions of particles with sizes of 0-0.15 mm, 0.15-0.3 mm, 0.3-0.45 mm, 0.45-1.2 mm, and 1.2-2.5 mm in the siliceous material are 35-50%, 25-35%, 3-7%, 3-7%, and 3-6%, respectively. Alternatively, the siliceous material is one or more of fly ash, sand, and tailings sand, and the SiO2 content of the siliceous material is ≥65wt%.

[0031] The method for preparing autoclaved bricks in this embodiment of the invention includes the following steps:

[0032] S1. Mix the aerated concrete waste material, titanium-containing blast furnace slag, cementitious materials, and siliceous materials evenly to obtain a mixed dry material. Add water to the mixed dry material to obtain a mixture.

[0033] S2. Allow the mixture to stand and digest in a natural environment for 4-10 hours to obtain the billet.

[0034] S3. Pour the billet into the brick mold and use a pressure of 20MPa to make the green brick;

[0035] S4. Place the green bricks into an autoclave and steam them at 185℃ and 1.0-1.2MPa for 5-8 hours to obtain autoclaved bricks.

[0036] Example 1

[0037] As a preferred embodiment of the present invention, the autoclaved brick of this embodiment has the following specific composition as shown in Table 1:

[0038] Table 1

[0039] Components Mass percentage (wt%) Aerated concrete waste 15 Titanium-containing blast furnace slag 15 Low-carbon cementitious material damp waste 12 Tailings sand 58

[0040] Example 2

[0041] As a preferred embodiment of the present invention, the autoclaved brick of this embodiment has the following specific composition as shown in Table 2:

[0042] Table 2

[0043] Components Mass percentage (wt%) Aerated concrete waste 15 Titanium-containing blast furnace slag 15 Low-carbon cementitious material damp waste 12 fly ash 30 Tailings sand 28

[0044] Example 3

[0045] As a preferred embodiment of the present invention, the autoclaved brick of this embodiment has the following specific composition as shown in Table 3:

[0046] Table 3

[0047] Components Mass percentage (wt%) Aerated concrete waste 15 Titanium-containing blast furnace slag 15 Low-carbon cementitious material damp waste 12 fly ash 23 Quartz sand 15 Tailings sand 20

[0048] Example 4

[0049] As a preferred embodiment of the present invention, the autoclaved brick of this embodiment has the following specific composition as shown in Table 4:

[0050] Table 4

[0051] Components Mass percentage (wt%) Aerated concrete waste 13 Titanium-containing blast furnace slag 18 Low-carbon cementitious material damp waste 9 Tailings sand 60

[0052] Example 5

[0053] As a preferred embodiment of the present invention, the autoclaved brick of this embodiment has the following specific composition as shown in Table 5:

[0054] Table 5

[0055] Components Mass percentage (wt%) Aerated concrete waste 10 Titanium-containing blast furnace slag 12 Low-carbon cementitious material damp waste 13 fly ash 65

[0056] Example 6

[0057] As a preferred embodiment of the present invention, the autoclaved brick of this embodiment has the following specific composition as shown in Table 6:

[0058] Table 6

[0059] Components Mass percentage (wt%) Aerated concrete waste 15 Titanium-containing blast furnace slag 20 Low-carbon cementitious material damp waste 15 Quartz sand 50

[0060] Example 7

[0061] As a preferred embodiment of the present invention, the autoclaved brick of this embodiment has the following specific composition as shown in Table 7:

[0062] Table 7

[0063] Components Mass percentage (wt%) Aerated concrete waste 15 Titanium-containing blast furnace slag 20 Low-carbon cementitious material damp waste 10 sand 55

[0064] Example 8

[0065] As a preferred embodiment of the present invention, the autoclaved brick of this embodiment has the following specific composition as shown in Table 8:

[0066] Table 8

[0067]

[0068]

[0069] Example 9

[0070] As a preferred embodiment of the present invention, the autoclaved brick of this embodiment has the following specific composition as shown in Table 9:

[0071] Table 9

[0072] Components Mass percentage (wt%) Aerated concrete waste 15 Titanium-containing blast furnace slag 15 Low-carbon cementitious materials 12 fly ash 58

[0073] Example 10

[0074] As a preferred embodiment of the present invention, the autoclaved brick of this embodiment has the following specific composition as shown in Table 10:

[0075] Table 10

[0076] Components Mass percentage (wt%) Aerated concrete waste 15 Titanium-containing blast furnace slag 15 Low-carbon cementitious materials 12 Quartz sand 58

[0077] Example 11

[0078] As a preferred embodiment of the present invention, the autoclaved brick of this embodiment has the following specific composition as shown in Table 11:

[0079] Table 11

[0080] Components Mass percentage (wt%) Aerated concrete waste 15 Titanium-containing blast furnace slag 15 Low-carbon cementitious materials 12 sand 58

[0081] Example 12

[0082] As a preferred embodiment of the present invention, the autoclaved brick of this embodiment has the following specific composition as shown in Table 12:

[0083] Table 12

[0084] Components Mass percentage (wt%) Aerated concrete waste 15 Titanium-containing blast furnace slag 15 Low-carbon cementitious materials 12 fly ash 25 sand 33

[0085] Comparative Example 1

[0086] This comparative example of an autoclaved brick has the same composition as Example 1, except that the low-carbon cementitious material wetted waste is replaced with quicklime. The preparation method is also the same as in Example 1. The specific composition is shown in Table 13.

[0087] Table 13

[0088] Components Mass percentage (wt%) Aerated concrete waste 15 Titanium-containing blast furnace slag 15 quicklime 12 Tailings sand 58

[0089] Comparative Example 2

[0090] This comparative example of an autoclaved brick has the same composition as Example 1, except that the low-carbon cementitious material wetted waste is replaced with cement. The preparation method is also the same as in Example 1. The specific composition is shown in Table 14.

[0091] Table 14

[0092] Components Mass percentage (wt%) Aerated concrete waste 15 Titanium-containing blast furnace slag 15 cement 12 Tailings sand 58

[0093] Autoclaved bricks prepared in Examples 1-12 and Comparative Examples 1-2 were tested for mechanical properties such as strength and frost resistance. The test methods were in accordance with GB 50574-2010 and GB 11945-2019. The test results are shown in Table 15.

[0094] Table 15

[0095]

[0096] As shown in Table 15, when using low-carbon cementitious materials or damp waste materials in this embodiment, the compressive strength of the prepared autoclaved bricks mostly reaches above 20 MPa, the flexural strength reaches above 5 MPa, and the frost resistance also meets the requirements of GB50574-2010 Unified Technical Specification for Application of Wall Materials and GB 11945-2019 Technical Requirements for MU20 grade in autoclaved lime-sand solid bricks and solid blocks. When the amount of tailings sand and titanium-containing blast furnace slag is increased, the crystalline silicon content also changes due to the reduction of calcareous materials and the increase of blast furnace slag, resulting in a decrease in the overall calcium-silicon ratio and a reduction in the mechanical properties of the autoclaved bricks. However, the strength can still reach 15 MPa, meeting the technical requirements of MU15 grade, and other properties also meet the requirements. Therefore, the autoclaved bricks prepared by this invention have good stability and can meet the needs of existing applications.

[0097] Figure 1 The image shows the microstructure of the autoclaved brick prepared in Example 1. As can be seen from the image, the product contains a large number of needle-shaped tobermorite and aluminum-substituted tobermorite, which are evenly distributed in the product structure, interpenetrating and connecting aggregates such as sand and titanium-containing slag. The structure is dense and improves the strength of the autoclaved brick.

[0098] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit the invention, nor are they intended to limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. That is to say, any changes or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but whose technical problems are still consistent with the present invention, should be included within the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing autoclaved bricks, characterized in that, Includes the following steps: S1. Mix the aerated concrete waste material, titanium-containing blast furnace slag, cementitious materials, and siliceous materials evenly to obtain a mixed dry material. Add water to the mixed dry material to obtain a mixture. S2. Allow the mixture to stand and digest in a natural environment for 4-10 hours to obtain the billet. S3. Pour the billet into the brick mold and use a pressure of 20MPa to make the green brick; S4. Place the green bricks into an autoclave and steam them at 185℃ and 1.0-1.2MPa for 5-8 hours to obtain autoclaved bricks. The cementing material is one or both of low-carbon cementing materials or damp waste of low-carbon cementing materials. The mineral composition of the low-carbon cementitious material is: f-CaO: 24-40wt%, C2S: 30-55wt%. : 1-10wt%, C4AF: 0.1-10wt%, CaSO4: 0.1-10wt%; The mineral composition of the damp waste low-carbon cementitious material is: f-CaO: 5-35wt%, C2S: 25-50wt%. :0.1-10wt%, C4AF: 0.1-10wt%, CaSO4: 0.1-10wt%, Ca(OH)2: 1-15wt%; The siliceous material is one or more of fly ash, quartz sand, and tailings sand.

2. The method for preparing autoclaved bricks according to claim 1, characterized in that, The mass percentages of the aerated concrete waste, titanium-containing blast furnace slag, cementitious materials, and siliceous materials are 10-15wt%, 12-20wt%, 8-15wt%, and 50-65wt%, respectively, and the amount of water added accounts for 8-14wt% of the mass of the mixed dry materials.

3. The method for preparing autoclaved bricks according to claim 1, characterized in that, The proportion of particles with a size of 0-0.08mm in the aerated concrete waste material is 90-95%.

4. The method for preparing autoclaved bricks according to claim 1, characterized in that, The titanium-containing blast furnace slag contains particles with sizes of 0.15-0.3 mm and 0-0.15 mm, accounting for 0-30% and 45-75% respectively.

5. The method for preparing autoclaved bricks according to claim 1, characterized in that, The titanium-containing blast furnace slag contains 20-30 wt% CaO, 25-30 wt% SiO2, 5-13 wt% Al2O3, and 5-12 wt% TiO2.

6. The method for preparing autoclaved bricks according to claim 1, characterized in that, The proportions of particles with sizes of 0-0.15mm, 0.15-0.3mm, 0.3-0.45mm, 0.45-1.2mm, and 1.2-2.5mm in the siliceous material are 35-50%, 25-35%, 3-7%, 3-7%, and 3-6%, respectively.

7. The method for preparing autoclaved bricks according to claim 1, characterized in that, The SiO2 content of the siliceous material is ≥65wt%.

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