Anti-freezing non-burned brick and preparation method thereof

Abstract

This invention discloses a frost-resistant, non-fired brick and its preparation method. By mass percentage, the frost-resistant, non-fired brick comprises 45-60% weathered granite soil and 40-55% cement. This invention utilizes weathered granite soil to prepare frost-resistant, non-fired bricks. Not only is the process simple, the materials readily available, and energy-saving, but it is also easy to scale up for industrial production. Furthermore, by adjusting the raw material ratio, a series of frost-resistant, non-fired brick products covering two strength grades, MU15 and MU20, can be prepared, demonstrating high practicality.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to an antifreeze, non-fired brick and its preparation method. Background Technology

[0002] Non-fired bricks are a new type of wall material, mainly made from waste materials such as fly ash, slag, coal gangue, tailings slag, and chemical slag. They are manufactured without high-temperature firing and have advantages such as high strength, good durability, standard dimensions, intact shape, and convenient construction. However, compared with traditional sintered bricks, non-fired bricks have lower strength. In cold regions, when moisture freezes inside the brick, it expands, damaging the internal structure and causing cracking or damage; that is, non-fired bricks have relatively poor freeze-thaw resistance. With the increasing national requirements for the quality of large-scale projects, while meeting strength requirements, the requirements for the freeze-thaw resistance of non-fired bricks are gradually increasing, becoming an important issue that urgently needs to be addressed.

[0003] With the rapid development of infrastructure in my country, the excessive use of natural sand in the construction industry has seriously affected the safety of water conservancy facilities such as river embankments and the stability of river channels. Coupled with environmental protection policies, the production of manufactured sand has increased dramatically, reaching 3 billion tons annually. However, during the mining process, the weathered layer covering the mine surface cannot be used as raw material and is stripped off and placed in stockpiles. This not only occupies a large amount of land resources, but also poses a significant risk of dust storms, landslides, and other disasters, seriously threatening the safety of nearby residents. Therefore, the resource utilization of weathered soil is urgently needed.

[0004] Currently, there are few patents on the preparation of frost-resistant non-fired bricks using weathered soil, and the theoretical and practical development is still incomplete. Among existing technologies, patent CN106082947A discloses a type of frost-resistant non-fired brick using flue gas dust removal soil, red soil, halloysite, coal gangue, natural sand, alkalized cotton stalks, and Kiryu sand as raw materials. The process involves grinding, mixing, pressing, and curing to produce a frost-resistant non-fired brick product with a 28-day compressive strength of 19 MPa and a mass loss of 1.3% and a strength loss of 2.2% after freeze-thaw cycles. However, this method uses complex raw materials and does not solve the problem of excessive use of natural sand. Furthermore, the raw material pretreatment stage requires grinding and other processes, and the finished product curing needs to be carried out in a 65% pure CO2 atmosphere, making the process complex and costly. Patent CN116082019A discloses an environmentally friendly, non-fired brick produced using granite mine tailings and its preparation method. The method uses granite mine tailings, cement, quicklime, and water glass as raw materials, and prepares the non-fired bricks through processes such as mixing, aging, molding, and steam curing. The final product is a non-fired brick with a compressive strength of 18.4 MPa. However, this method has drawbacks such as complex raw material combinations and a lengthy aging period. Furthermore, steam curing must be carried out at 80-100 °C, making the process cumbersome and costly. Additionally, it does not investigate the frost resistance of the brick material. Summary of the Invention

[0005] To address the aforementioned shortcomings, the present invention aims to provide a frost-resistant, non-fired brick and its preparation method, thereby solving the technical problems of complex raw materials and high production costs in the preparation of frost-resistant, non-fired bricks in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a frost-resistant, non-fired brick, comprising, by mass percentage, 45-60% weathered granite soil and 40-55% cement.

[0008] Preferably, the weathered soil of granite includes SiO2, Al2O3, Fe2O3, K2O, Na2O, MgO and CaO, wherein the mass ratio of SiO2, Al2O3, Fe2O3, K2O, Na2O, MgO and CaO is (40~50):(20~30):(5~10):(1~2):(1~2):(1~2):(1~2).

[0009] Preferably, the particle size of weathered granite soil is ≤4.75 mm.

[0010] Preferably, the cement is silicate cement.

[0011] Preferably, the silicate cement is one or more of grade 52.5 silicate cement, grade 42.5 silicate cement, and grade 32.5 silicate cement.

[0012] Secondly, the present invention provides a method for preparing frost-resistant, non-fired bricks, comprising the following steps:

[0013] S1. The weathered granite soil is sieved to obtain the first material;

[0014] S2. Mix the first material with cement evenly to obtain the second material;

[0015] S3. Mix the second material with water evenly, and then press it into shape to obtain a brick blank;

[0016] S4. Curing the brick blanks yields frost-resistant, non-fired bricks.

[0017] Preferably, in step S1, the sieve used for sieving is 4 mesh.

[0018] Preferably, in step S3, the amount of water used is 15-20% of the mass of the second material.

[0019] Preferably, in step S3, the pressing pressure is 20~25 MPa and the molding time is 2~5 min.

[0020] Preferably, in step S4, the curing temperature is 20~27℃, the curing humidity is 90%~97%, and the curing time is 28~30 days.

[0021] The beneficial effects of this invention are:

[0022] This invention uses weathered granite soil and cement as the main raw materials to produce non-fired bricks with a 28-day compressive strength of 17-25 MPa, a softening coefficient of 87-98%, and a strength loss rate of less than 10% after freeze-thaw cycles. These meet the performance requirements for non-fired bricks in JC / T 422-2007 "Non-Sintered Waste Tailings Bricks". This not only achieves efficient, harmless, and resource-based utilization of weathered soil but also broadens the raw material sources for non-fired bricks, realizing a high degree of unity between environmental, economic, and social benefits. At the same time, it has significant practical implications for promoting the sustainable and green development of the building materials industry.

[0023] This invention uses weathered granite soil as the main material to prepare frost-resistant, non-fired bricks, turning weathered soil into a valuable resource. The resulting non-fired bricks have higher strength and excellent frost resistance, saving clay raw materials and natural sand. Furthermore, the frost-resistant non-fired bricks can be prepared simply by mixing, pressing, and curing, eliminating lengthy preliminary raw material processing and the energy-intensive sintering step. The preparation process is simple, the curing conditions are mild, and the production cost is low. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0025] Figure 1 This is a process flow diagram of the preparation process of an antifreeze, non-fired brick according to the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] The main chemical components of weathered granite soil are SiO2, Al2O3, and Fe2O3, etc., and its main properties are similar to those of building aggregates. It can be used as an admixture and aggregate in the production of non-fired bricks. Meanwhile, the Fe in weathered granite soil... 3+ During the cement hydration process, it will react with Al 3+ A displacement reaction occurs, resulting in the formation of large amounts of ferric calcite and ferric binder (FH3), which enhances the frost resistance of the unfired bricks. For example... Figure 1 As shown in the figure, an embodiment of the present invention provides a method for preparing frost-resistant, non-fired bricks, comprising the following steps:

[0028] S1. Pass the weathered granite soil through a 4-mesh sieve to obtain the first material;

[0029] S2. Mix 45-60% of the first material with 40-55% of the cement by mass percentage to obtain the second material.

[0030] S3. Mix the second material with water evenly, wherein the amount of water is 15-20% of the mass of the second material, and press it into shape at 20-25 MPa for 2-5 minutes to obtain a brick blank.

[0031] S4. Curing the brick blanks at 20~27℃ and 90%~97% humidity for 28~30 days yields frost-resistant, non-fired bricks.

[0032] This invention utilizes weathered granite soil to prepare frost-resistant, non-fired bricks. The process is simple, the materials are readily available, energy is saved, and it is easy to scale up production. Moreover, by adjusting the raw material ratio, a series of frost-resistant, non-fired brick products covering two strength grades, MU15 and MU20, can be prepared, making it highly practical.

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below.

[0034] The main chemical composition of the weathered granite soil used in the following examples and comparative examples is as follows: SiO2: 48.88%, Al2O3: 28.03%, Fe2O3: 8.68%, K2O: 1.86%, Na2O: 1.70%, MgO: 1.68%, CaO: 1.57%.

[0035] Example 1

[0036] A frost-resistant, non-fired brick is prepared as follows:

[0037] S1. Pass the weathered granite soil through a 4-mesh square-hole standard sieve to obtain the undersize material, which is the first material.

[0038] S2. Mix 45 wt% of the first material with 55 wt% of PO 525 silicate cement evenly to obtain the second material.

[0039] S3. Add municipal water accounting for 15 wt% of the second material to the second material, mix evenly, place in a mold, and press into shape under a tablet press. The molding pressure is 20 MPa and the molding time is 2 min to obtain a brick blank.

[0040] S4. The brick blanks are cured in a constant temperature and humidity curing chamber at 25 ℃ and 95% humidity for 28 days to obtain frost-resistant, non-fired bricks.

[0041] Example 2

[0042] A frost-resistant, non-fired brick is prepared as follows:

[0043] S1. Pass the weathered granite soil through a 4-mesh square-hole standard sieve to obtain the undersize material, which is the first material.

[0044] S2. Mix 50 wt% of the first material with 50 wt% of PO 525 silicate cement evenly to obtain the second material.

[0045] S3. Add municipal water accounting for 15 wt% of the second material to the second material, mix evenly, place in a mold, and press into shape under a tablet press. The molding pressure is 20 MPa and the molding time is 2 min to obtain a brick blank.

[0046] S4. The brick blanks are cured in a constant temperature and humidity curing chamber at 25 ℃ and 95% humidity for 28 days to obtain frost-resistant, non-fired bricks.

[0047] Example 3

[0048] A frost-resistant, non-fired brick is prepared as follows:

[0049] S1. Pass the weathered granite soil through a 4-mesh square-hole standard sieve to obtain the undersize material, which is the first material.

[0050] S2. Mix 55 wt% of the first material with 45 wt% of PO 525 silicate cement evenly to obtain the second material.

[0051] S3. Add municipal water accounting for 15 wt% of the second material to the second material, mix evenly, place in a mold, and press into shape under a tablet press. The molding pressure is 20 MPa and the molding time is 2 min to obtain a brick blank.

[0052] S4. The brick blanks are cured in a constant temperature and humidity curing chamber at 25 ℃ and 95% humidity for 28 days to obtain frost-resistant, non-fired bricks.

[0053] Example 4

[0054] A frost-resistant, non-fired brick is prepared as follows:

[0055] S1. Pass the weathered granite soil through a 4-mesh square-hole standard sieve to obtain the undersize material, which is the first material.

[0056] S2. Mix 60 wt% of the first material with 40 wt% of PO 525 silicate cement evenly to obtain the second material.

[0057] S3. Add municipal water accounting for 15 wt% of the second material to the second material, mix evenly, place in a mold, and press into shape under a tablet press. The molding pressure is 20 MPa and the molding time is 2 min to obtain a brick blank.

[0058] S4. The brick blanks are cured in a constant temperature and humidity curing chamber at 25 ℃ and 95% humidity for 28 days to obtain frost-resistant, non-fired bricks.

[0059] Comparative Example 1

[0060] A frost-resistant, non-fired brick is prepared as follows:

[0061] S1. Pass the weathered granite soil through a 4-mesh square-hole standard sieve to obtain the undersize material, which is the first material.

[0062] S2. Mix 65 wt% of the first material with 35 wt% of PO 525 silicate cement evenly to obtain the second material.

[0063] S3. Add municipal water accounting for 15 wt% of the second material to the second material, mix evenly, place in a mold, and press into shape under a tablet press. The molding pressure is 20 MPa and the molding time is 2 min to obtain a brick blank.

[0064] S4. The brick blanks are cured in a constant temperature and humidity curing chamber at 25 ℃ and 95% humidity for 28 days to obtain frost-resistant, non-fired bricks.

[0065] Comparative Example 2

[0066] The only difference between this comparative example and Example 2 is that the weathered granite soil was subjected to magnetic separation to remove iron. The main chemical components of the weathered granite soil after magnetic separation are SiO2: 45.66%, Al2O3: 26.53%, Fe2O3: 4.45%, K2O: 1.51%, Na2O: 1.46%, MgO: 1.23%, and CaO: 1.04%.

[0067] The performance of the non-fired bricks obtained in Examples 1-4 and Comparative Examples 1-2 were tested respectively, and the results are shown in Table 1.

[0068] Table 1. Test results of Examples 1-4 and Comparative Examples 1-2

[0069]

[0070] As can be seen from Table 1, the non-fired bricks prepared in Examples 1-4 of this invention have excellent compressive strength, water absorption, frost resistance and softening coefficient, which meet the requirements of JC / T 422-2007 "Non-sintered waste tailings bricks", covering two strength grades, MU15 and MU20. After 15 freeze-thaw cycles, the brick structure is stable and there are no obvious defects in appearance.

[0071] Compared to Example 1, Comparative Example 1 used a higher amount of weathered soil. The compressive strength, water absorption, softening coefficient, and frost resistance of the prepared non-fired bricks were all inferior to those of Example 1. In fact, the compressive strength dropped sharply to 12.04 MPa after freeze-thaw cycles, with a strength loss rate of 16.33%. This is because the weathered soil has a larger particle size. With the increase of weathered soil content, the porosity of the brick's internal structure increases, resulting in a decrease in density and an increase in water absorption. During freeze-thaw cycles, a higher water absorption rate means that the expansion volume of water during freeze-thaw cycles is larger, which means that the brick structure is more easily damaged, which is macroscopically manifested as a decrease in the compressive strength of the brick.

[0072] Comparative Example 2 showed a higher strength loss after freeze-thaw compared to Example 2. This is due to Fe 3+ It can promote the hydration activity of cement during the hydration process, and interact with Al. 3+ The substitution process generates a large amount of ferric calcite and ferric binder (FH3), making the brick structure denser. This results in increased compressive strength, reduced water absorption, increased density, and superior frost resistance. 3+ The reduction in content had a negative impact on these properties.

[0073] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0074] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A frost-resistant, non-fired brick, characterized in that, by mass percentage, it comprises 45-60% weathered granite soil and 40-55% cement; the main chemical composition of the weathered granite soil, by mass percentage, is: SiO2: 48.88%, Al2O3: 28.03%, Fe2O3: 8.68%, K2O: 1.86%, Na2O: 1.70%, MgO: 1.68%, CaO: 1.57%.

2. The frost-resistant, non-fired brick according to claim 1, characterized in that, The particle size of the weathered granite soil is ≤4.75mm.

3. The frost-resistant, non-fired brick according to claim 1, characterized in that, The cement is silicate cement.

4. The frost-resistant, non-fired brick according to claim 3, characterized in that, The silicate cement is one or more of grade 52.5 silicate cement, grade 42.5 silicate cement, and grade 32.5 silicate cement.

5. A method for preparing frost-resistant, non-fired bricks as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1. The weathered granite soil is sieved to obtain the first material; S2. Mix the first material with cement evenly to obtain the second material; S3. Mix the second material with water evenly, and then press it into shape to obtain a brick blank; S4. Curing the brick blanks to obtain frost-resistant, non-fired bricks.

6. The method for preparing frost-resistant, non-fired bricks according to claim 5, characterized in that, In step S1, the sieve used for sieving has a mesh size of 4.

7. The method for preparing frost-resistant, non-fired bricks according to claim 5, characterized in that, In step S3, the amount of water used is 15-20% of the mass of the second material.

8. The method for preparing frost-resistant, non-fired bricks according to claim 5, characterized in that, In step S3, the pressing pressure is 20~25 MPa and the molding time is 2~5 min.

9. The method for preparing frost-resistant, non-fired bricks according to claim 5, characterized in that, In step S4, the curing temperature is 20~27℃, the curing humidity is 90%~97%, and the curing time is 28~30 days.

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