A high-density washed sand mud unfired brick and its preparation method

Abstract

The invention belongs to the technical field of building materials, and specifically discloses a high-density washed sand mud unfired brick and a preparation method thereof. The unfired brick comprises 60-90 parts of washed sand mud, 10-30 parts of stone powder, 5-20 parts of cement, 1-5 parts of slaked lime, 0.1-1 part of redispersible latex powder and 5-10 parts of water. The preparation process comprises the following steps: firstly dry-mixing the washed sand mud, stone powder, cement, slaked lime and redispersible latex powder; then spraying water into the dry mixture until a wet mixture with a moisture content within a certain precise range is obtained; finally, pouring the wet mixture into a static pressure brick mold and performing secondary static pressure molding under a pressure within a certain precise range. The washed sand mud unfired brick obtained by the method has the characteristics of high strength, small shrinkage, excellent water resistance, low carbon and environmental protection, and significant economic benefits as a whole, and has good promotion prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and specifically discloses a high-density washed sand mud unfired brick and a preparation method thereof. Background Art

[0002] Sand washing mud refers to the material containing a large amount of mud, sand, water and impurities produced after cleaning in the process of preparing machine-made sand in order to improve the quality of machine-made sand and gravel.

[0003] Although sand-washing mud is a waste material, it also has potential value. Sand-washing mud contains a certain proportion of useful components, such as clay and fine sand (the fine sand is primarily composed of tiny rock fragments formed through erosion and weathering, with a particle size distribution ranging from 1μm to 1000μm). Studies have shown that mineral components in clay, such as kaolinite, illite, and montmorillonite, can react with strong alkali to form hydration products CSH and CAH. Furthermore, when the fine sand particle size is less than 75μm, it exhibits a certain degree of pozzolanic activity and can also produce hydration products under alkaline stimulation. Utilizing these useful components in sand-washing mud to produce unfired bricks not only transforms sand-washing mud into valuable resources, but also aligns well with current green development requirements. Unfired bricks, which require no calcination and are formed by static pressing, are energy-efficient, environmentally friendly, and low-carbon. However, unfired bricks made from sand-washing mud often have poor water resistance and are prone to cracking, severe cracking, or even disintegration upon contact with water, a major obstacle hindering their widespread application. To improve the water resistance of unfired bricks, research shows that increasing their density is one of the most effective ways.

[0004] In response to the problem of poor water resistance of washed sand mud unfired bricks, the existing technology has proposed corresponding improvement methods. For example, patent CN110002824 proposes a kind of unfired brick and its production method. The unfired brick uses soil and recycled aggregate as raw materials for making bricks, cement as gelling agent, and with the help of admixtures and fusion agents, the soil and fusion agent are wrapped and fused together, making full use of waste residues and waste materials. The obtained soil unfired brick has the characteristics of good waterproof effect. However, there are two obvious shortcomings in this invention. First, the soil unfired bricks prepared by this invention patent use curing agents, fusion agents and a variety of admixtures, which are very expensive; second, the steps of preparing curing agents and fusion agents are cumbersome, and finally the unfired bricks need to be coated with curing agents. The overall preparation process is complicated and not conducive to large-scale promotion.

[0005] Based on the above-mentioned defects of washed sand mud unfired bricks and the shortcomings of previous inventions, the present invention plans to improve the density of washed sand mud unfired bricks from multiple aspects of optimizing the preparation process and component ratio, thereby improving its water resistance, and exploring a high-density washed sand mud unfired brick to achieve high added value utilization of washed sand mud and reduce production costs. Summary of the Invention

[0006] The main purpose of the present invention is to provide a high-density washed sand mud unburned brick and a preparation method thereof, so as to reduce production costs and realize high added value utilization of washed sand mud.

[0007] To achieve the above objectives, the present invention provides the following technical solutions:

[0008] The high-density washed sand mud unburned brick is prepared from the following materials, calculated by weight: 60-90 parts of washed sand mud, 10-30 parts of stone powder, 5-20 parts of cement, 1-5 parts of slaked lime, 0.1-1 part of redispersible latex powder and 5-10 parts of water.

[0009] Preferably, the sand washing mud is the mud produced in the process of machine-made sand washing, with a sand content of ≤30%, a mud content of ≥60%, main components of SiO2, Al2O3 and CaO, an organic matter content of ≤15%, a water content of ≥30%, and a particle size range of ≤5 mm.

[0010] Preferably, the stone powder is stone powder collected during the ore crushing process of the machine-made sand crushing equipment, and the particle size is 0.01mm to 8mm.

[0011] Preferably, the cement is ordinary Portland cement.

[0012] Preferably, the calcium content of the slaked lime is ≥95%, and the slaked lime is a white powdery solid.

[0013] Preferably, the redispersible latex powder is a water-soluble white to light beige or light yellow powder, the active ingredient of which is a flexible copolymer of vinyl chloride and ethylene or a flexible terpolymer of vinyl chloride, ethylene and vinyl laurate, with a solid content of ≥98% and a bulk density of 400-550 kg / m 3 .

[0014] Furthermore, the present invention also provides a method for preparing high-density washed sand mud unburned bricks, comprising the following steps:

[0015] S1. Air-dry and crush the washed sand into specified specifications;

[0016] S2. According to the mass ratio, measure 60-90 parts of sand washing mud, 10-30 parts of stone powder, 5-20 parts of cement, 1-5 parts of slaked lime, 0.1-1 parts of redispersible latex powder and 5-10 parts of water for use;

[0017] S3. The washed sand mud, stone powder, cement, slaked lime and redispersible latex powder were mixed and dry-mixed for 4 minutes to obtain a uniform mixture;

[0018] S4. Use a spray bottle to spray the weighed water into the dry mixture until the moisture content is controlled within the range of 12% ± 0.5%. The wet mixing time is controlled within 5 minutes.

[0019] S5. The moisture content of the washed sand mud unfired brick mixture is poured into the static pressure brick machine mold, the pressure of the press is controlled at 12 ± 1MPa, and the secondary static pressure method is used to obtain the washed sand mud unfired brick;

[0020] S6. Place the obtained washed sand mud unfired bricks in an environment of 23±2°C and a relative humidity of 65±15%, cover with a film and cure for 28 days to obtain high-density washed sand mud unfired bricks, and test their strength and water resistance.

[0021] The high-density washed sand mud unburned bricks obtained by the invention are mainly used in the field of construction engineering.

[0022] The present invention has the following advantages:

[0023] 1) Nearly 80% of the weight of the present invention is waste (washing mud accounts for about 70% of the total mass, and stone powder accounts for about 10% of the total mass). It has the characteristics of low cost and can absorb sand washing mud and stone powder waste on a large scale, thus avoiding the occupation and pollution of land resources by these waste materials. At the same time, the sand washing mud unburned bricks prepared with the optimal ratio have high density, a softening coefficient of up to 0.9, and excellent water resistance.

[0024] 2) The present invention improves the density of washed sand mud unfired bricks by optimizing the preparation process and component ratios in many aspects, thereby improving the water resistance of washed sand mud unfired bricks. In terms of preparation process, the density of unfired bricks is maximized by precisely controlling the moisture content of the wet mix (12% ± 0.5%) and the static pressing pressure (12 ± 1MPa). In terms of ratio optimization, slaked lime is added to replace cement and redispersible latex powder is added to promote the internal reaction of the unfired bricks to generate more hydration products, thereby improving the density of the unfired bricks.

[0025] 3) The present invention pre-mixes the washed sand mud, stone powder, cement, slaked lime, and redispersible latex powder. The purpose of the pre-mixing is mainly to allow the cement, slaked lime, and redispersible latex powder to be evenly distributed around the washed sand mud and stone powder particles, which is conducive to the generation of hydration products between the washed sand mud and the stone powder, ensuring the density of the unfired bricks and improving their water resistance. The specific analysis is as follows: In the early pre-mixing process, the washed sand mud, stone powder, cement, slaked lime, and redispersible latex powder have been fully mixed. When water is added, the redispersible latex powder will be redispersed into an emulsion when it meets water. The emulsion can wrap up the evenly dispersed cement, slaked lime, washed sand mud, and stone powder. In this way, the hydration products generated by the reaction of slaked lime and cement can wrap the washed sand mud and stone powder around them, thereby increasing the density of the washed sand mud unfired bricks to improve their water resistance.

[0026] 4) The present invention mixes slaked lime and redispersible latex powder, which can achieve multiple effects of improving the crack resistance of washed sand mud unfired bricks, thereby increasing the density of washed sand mud unfired bricks to improve their water resistance. The specific analysis is as follows: the cement in the unfired brick will produce shrinkage stress during the hydration process, resulting in a decrease in volume and cracking of the unfired brick, affecting its water resistance. After adding slaked lime, on the one hand, slaked lime will precipitate crystals in a saturated state, and its ability to resist deformation is stronger than that of the hydration product gel, which can resist the shrinkage caused by the cement reaction to a certain extent. On the other hand, slaked lime will produce expansion stress during the hydration process, causing the volume of the unfired brick to increase and fill cracks. Adding an appropriate proportion of slaked lime can make the two stresses offset or balance each other, thereby reducing or eliminating the risk of shrinkage deformation and cracking of the unfired brick. After adding redispersible latex powder, the emulsion formed by the redispersible latex powder will form a continuous polymer film, which will increase the cohesion, adhesion and flexibility of the unfired brick, which is beneficial for the unfired brick to resist stress concentration and crack expansion, improve its density and thus improve water resistance.

[0027] 5) The present invention mixes slaked lime and redispersible latex powder, which is beneficial to further ensure that the slaked lime and the active ingredients in the clay and fine sand in the sand washing mud (active silica, active alumina, etc.) continue to undergo a pozzolanic reaction, generating more hydration products, thereby improving the density of the sand washing mud unfired bricks and increasing their water resistance. The specific analysis is as follows: the slaked lime requires the participation of water to undergo a pozzolanic reaction, and the redispersible latex powder used in the present invention will be redispersed into an emulsion after encountering water. The emulsion can wrap the unfired bricks and prevent the water in the unfired bricks from being lost too quickly. Adequate water is beneficial to promote the reaction of slaked lime to generate more hydration products to wrap the sand washing mud, stone powder and other materials, thereby improving the density of the unfired bricks and improving their water resistance.

[0028] 6) The slaked lime used in the present invention can release calcium hydroxide and maintain the alkaline environment of the unburned brick, which is beneficial to improve the density of the washed sand mud unburned brick and thus improve its water resistance. The specific analysis is as follows: The washed sand mud contains components such as clay and fine sand, which need to be active in a strong alkaline environment. However, with the hydration reaction of cement, the alkalinity of the unburned brick will decrease. At this time, the clay and fine sand components in the washed sand mud cannot fully exert their activity due to insufficient alkalinity, which limits the formation of hydration products. After adding slaked lime, the unburned brick can maintain a strong alkaline environment, which is beneficial to the clay and fine sand in the washed sand mud to exert their activity, thereby promoting the further formation of hydration products, improving the density of the unburned brick and thus improving its water resistance. DETAILED DESCRIPTION

[0029] To make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention. Materials used in the present invention:

[0030] Sand washing mud is the mud produced in the process of machine-made sand washing. Its sand content is ≤30%, mud content is ≥60%, main components are SiO2, Al2O3 and CaO, organic matter content is ≤15%, water content is ≥30%, and particle size range is ≤5mm.

[0031] Stone powder is the stone powder collected during the ore crushing process of machine-made sand crushing equipment, with a particle size of 0.01mm to 8mm.

[0032] The cement is ordinary Portland cement.

[0033] The calcium content of slaked lime is ≥95%, and it is a white powdery solid.

[0034] Redispersible latex powder is a water-soluble white to light beige or light yellow powder. The active ingredient is a flexible copolymer of vinyl chloride and ethylene or a flexible terpolymer of vinyl chloride, ethylene and vinyl laurate. The solid content is ≥98% and the bulk density is 400-550 kg / m 3 The sources of the redispersible latex powder products are: Wacker 3030H (a flexible copolymer of vinyl chloride and ethylene) and Wacker 8031H (a flexible terpolymer of vinyl chloride, ethylene and vinyl laurate).

[0035] The water meets the requirements of the construction industry construction standard JGJ63-2006 "Standard for Water Use in Concrete".

[0036] Example 1

[0037] A high-density washed sand mud unburned brick is composed, by weight, of 90 parts of washed sand mud, 30 parts of stone powder, 20 parts of cement, 5 parts of slaked lime, 1 part of redispersible latex powder and 8 parts of water.

[0038] Among them, the average particle size of the washed sand mud is 3mm, the effective ingredient of the redispersible latex powder is a flexible copolymer of vinyl chloride and ethylene (product source: Wacker 3030H), the moisture content of the wet mixture before pressing is 11.5%, and the static pressing pressure is 11MPa.

[0039] The preparation method of high-density washed sand mud unburned bricks comprises the following steps:

[0040] S1. Air-dry and crush the washed sand into specified specifications;

[0041] S2. Measure the raw materials according to the mass ratio and set aside;

[0042] S3. The washed sand mud, stone powder, cement, slaked lime and redispersible latex powder were mixed and dry-mixed for 4 minutes to obtain a uniform mixture;

[0043] S4. Spray the weighed water into the dry mixture using a spray bottle until the moisture content is controlled to 11.5%, and the wet mixing time is controlled within 5min;

[0044] S5. The moisture content of the washed sand mud unfired brick mixture is poured into the static pressure brick machine mold, the pressure of the press is controlled at 11MPa, and the secondary static pressure method is used to obtain the washed sand mud unfired brick;

[0045] S6. Place the obtained washed sand mud unfired bricks in an environment of 23±2°C and a relative humidity of 65±15%, cover with a film and cure for 28 days to obtain high-density washed sand mud unfired bricks, and test their strength and water resistance.

[0046] Example 2

[0047] A high-density washed sand mud unfired brick is composed, by weight, of 80 parts of washed sand mud, 20 parts of stone powder, 15 parts of cement, 3 parts of slaked lime, 0.8 parts of redispersible latex powder and 7 parts of water. The preparation method is the same as that of Example 1.

[0048] Among them, the average particle size of the washed sand mud is 2mm, the effective ingredient of the redispersible latex powder is a flexible copolymer of vinyl chloride and ethylene (product source: Wacker 3030H), the moisture content of the wet mixture before pressing is 12%, and the static pressing pressure is 12MPa.

[0049] Example 3: A high-density washed sand mud unfired brick, which is composed of 70 parts of washed sand mud, 15 parts of stone powder, 10 parts of cement, 2 parts of slaked lime, 0.6 parts of redispersible latex powder and 6.5 parts of water, by weight. The preparation method is the same as that of Example 1.

[0050] Among them, the average particle size of the washed sand mud is 2mm, the effective ingredient of the redispersible latex powder is a flexible terpolymer of vinyl chloride, ethylene and vinyl laurate (product source: Wacker 8031H), the moisture content of the wet mixture before pressing is 12.5%, and the static pressing pressure is 13MPa.

[0051] Comparative Example 1: The unburned bricks of this scheme do not contain redispersible latex powder and slaked lime

[0052] A high-density washed sand mud unfired brick is composed, by weight, of 80 parts of washed sand mud, 20 parts of stone powder, 18 parts of cement and 7 parts of water.

[0053] Preparation method: Since redispersible latex powder and slaked lime are not added, the washed sand mud, stone powder and cement are directly dry-mixed for 4 minutes in step S3 to ensure that the cement particles are evenly distributed around the washed sand mud and stone powder particles. The other preparation steps are the same as in Example 1.

[0054] Among them, the average particle size of the washed sand mud is 2mm, the moisture content of the wet mixture before pressing is 12%, and the static pressing pressure is 12MPa.

[0055] Comparative Example 2: The unfired bricks of this scheme do not contain redispersible latex powder

[0056] A high-density washed sand mud unburned brick is composed, by weight, of 80 parts of washed sand mud, 20 parts of stone powder, 15 parts of cement, 3 parts of slaked lime and 7 parts of water.

[0057] Preparation method: Since no redispersible latex powder is added, step S3 directly dry-mixes the washed sand mud, stone powder, cement and slaked lime for 4 minutes to ensure that the cement particles and slaked lime particles are evenly distributed around the washed sand mud and stone powder particles. The other preparation steps are the same as Example 1.

[0058] Among them, the average particle size of the washed sand mud is 2mm, the moisture content of the wet mixture before pressing is 12%, and the static pressing pressure is 12MPa.

[0059] Comparative Example 3: The unburned bricks in this scheme do not contain slaked lime

[0060] A high-density washed sand mud unfired brick is composed, by weight, of 80 parts of washed sand mud, 20 parts of stone powder, 18 parts of cement, 0.8 parts of redispersible latex powder and 7 parts of water.

[0061] Preparation method: Since slaked lime is not added, step S3 directly dry-mixes the washed sand mud, stone powder, cement and redispersible latex powder for 4 minutes to ensure that the cement particles and redispersible latex powder are evenly distributed around the washed sand mud and stone powder particles. The other preparation steps are the same as Example 1.

[0062] Among them, the average particle size of the washed sand mud is 2mm, the effective ingredient of the redispersible latex powder is a flexible copolymer of vinyl chloride and ethylene (product source: Wacker 3030H), the moisture content of the wet mixture before pressing is 12%, and the static pressing pressure is 12MPa.

[0063] Comparative Example 4: The unburned bricks of this scheme use coarse washed sand mud instead of the washed sand mud in Example 2

[0064] A high-density washed sand mud unfired brick is composed, by weight, of 80 parts of washed sand mud, 20 parts of stone powder, 15 parts of cement, 3 parts of slaked lime, 0.8 parts of redispersible latex powder and 7 parts of water. The preparation method is the same as that of Example 1.

[0065] Among them, the average particle size of the washed sand mud is 9mm, the effective ingredient of the redispersible latex powder is a flexible copolymer of vinyl chloride and ethylene (product source: Wacker 3030H), the moisture content of the wet mixture before pressing is 12%, and the static pressing pressure is 12MPa.

[0066] Comparative Example 5: The effective ingredient of the unburned brick redispersible latex powder of this scheme is a rigid copolymer of vinyl acetate and ethylene copolymer

[0067] A high-density washed sand mud unfired brick is composed, by weight, of 80 parts of washed sand mud, 20 parts of stone powder, 15 parts of cement, 3 parts of slaked lime, 0.8 parts of redispersible latex powder and 7 parts of water. The preparation method is the same as that of Example 1.

[0068] Among them, the average particle size of the washed sand mud is 2mm, the effective ingredient of the redispersible latex powder is a rigid copolymer of vinyl acetate and ethylene copolymer (product source: Wacker 7550A), the moisture content of the wet mixture before pressing is 12%, and the static pressing pressure is 12MPa.

[0069] Comparative Example 6: The unburned bricks in this scheme have a low moisture content before the wet mixture is pressed.

[0070] A high-density washed sand mud unfired brick is composed, by weight, of 80 parts of washed sand mud, 20 parts of stone powder, 15 parts of cement, 3 parts of slaked lime, 0.8 parts of redispersible latex powder and 7 parts of water. The preparation method is the same as that of Example 1.

[0071] Among them, the average particle size of the washed sand mud is 2mm, the effective ingredient of the redispersible latex powder is a flexible copolymer of vinyl chloride and ethylene (product source: Wacker 3030H), the moisture content of the wet mixture before pressing is 9%, and the static pressing pressure is 12MPa.

[0072] Comparative Example 7: The unburned bricks in this scheme have too high a moisture content before the wet mixture is pressed.

[0073] A high-density washed sand mud unfired brick is composed, by weight, of 80 parts of washed sand mud, 20 parts of stone powder, 15 parts of cement, 3 parts of slaked lime, 0.8 parts of redispersible latex powder and 7 parts of water. The preparation method is the same as that of Example 1.

[0074] Among them, the average particle size of the washed sand mud is 2mm, the effective ingredient of the redispersible latex powder is a flexible copolymer of vinyl chloride and ethylene (product source: Wacker 3030H), the moisture content of the wet mixture before pressing is 14%, and the static pressing pressure is 12MPa.

[0075] Comparative Example 8: The static pressure of the unfired bricks in this scheme is too low

[0076] A high-density washed sand mud unfired brick is composed, by weight, of 80 parts of washed sand mud, 20 parts of stone powder, 15 parts of cement, 3 parts of slaked lime, 0.8 parts of redispersible latex powder and 7 parts of water. The preparation method is the same as that of Example 1.

[0077] Among them, the average particle size of the washed sand mud is 2mm, the effective ingredient of the redispersible latex powder is a flexible copolymer of vinyl chloride and ethylene (product source: Wacker 3030H), the moisture content of the wet mixture before pressing is 12%, and the static pressing pressure is 8MPa.

[0078] Comparative Example 9: The static pressure of the unfired bricks in this scheme is too high

[0079] A high-density washed sand mud unfired brick is composed, by weight, of 80 parts of washed sand mud, 20 parts of stone powder, 15 parts of cement, 3 parts of slaked lime, 0.8 parts of redispersible latex powder and 7 parts of water. The preparation method is the same as that of Example 1.

[0080] Among them, the average particle size of the washed sand mud is 2mm, the effective ingredient of the redispersible latex powder is a flexible copolymer of vinyl chloride and ethylene (product source: Wacker 3030H), the moisture content of the wet mixture before pressing is 12%, and the static pressing pressure is 15MPa.

[0081] The 28d compressive strength, drying shrinkage and softening coefficient of the washed sand mud unfired bricks were tested according to the "Test Methods for Wall Bricks" (GB / T 2542-2012). The performance test results of the washed sand mud unfired bricks obtained in the examples and the comparative examples are shown in Table 1

[0082] Table 1 Performance test results of washed sand mud unfired bricks obtained in Examples 1-3 and Comparative Examples 1-9

[0083]

[0084]

[0085] As can be seen from Table 1, the compressive strength and softening coefficient (characterizing water resistance, the larger the value, the better the water resistance of the washed sand mud unfired brick) of the embodiment are significantly improved compared with the control example 28d, and the drying shrinkage is significantly reduced; at the same time, it can be found from the embodiment and control examples 1, 2, and 3 that the compressive strength and softening coefficient of the washed sand mud unfired brick samples obtained in the embodiment are better than those of the control example, and the drying shrinkage is lower than that of the control example, indicating that the combined addition of slaked lime and redispersible latex powder improves the mechanical properties and water resistance of the washed sand mud unfired brick and is better than the single addition or non-addition of slaked lime or redispersible latex powder in reducing the drying shrinkage effect. In addition, it can be seen from Example 2 and Control Example 4 that the particle size of washed sand mud is a key parameter affecting the density of washed sand mud unfired bricks, that is, too coarse washed sand mud (the raw material particle size is too coarse, which will increase the pores between the particles and reduce the density) will reduce the density of the unfired brick, thereby affecting its various properties. Furthermore, it can be seen from Example 2 and Comparative Example 5 that the type of redispersible latex powder is also a key parameter affecting the density of washed sand mud unfired bricks.

[0086] From Example 2 and Comparative Examples 6 and 7, it can be seen that if the moisture content is too low or too high during the preparation process (on the one hand, too low a moisture content leads to lack of water in the hydration reaction, and the hydration product cannot be fully generated, which reduces the density; on the other hand, the friction between the wet mixture and the mold increases, and the corners of the unfired bricks are prone to corner defects; if the moisture content is too high, the free water in the wet mixture increases, which will lead to a decrease in the effective molding pressure and the inability to press densely), the density of the washed sand mud unfired brick will deteriorate and thus affect its various performances. It can be seen that appropriate moisture content is the key parameter affecting the density of the washed sand mud unfired brick.

[0087] From Example 2 and Comparative Examples 8 and 9, it can be seen that if the molding pressure during the preparation process is too low or too high (too low molding pressure will result in insufficient density of the unfired brick itself; too high molding pressure will cause gas to be introduced into the mixture during the stirring process, and the gas in the mixture will be over-compressed due to excessive pressure, which will produce a strong reaction force and cause the unfired brick to easily produce defects such as fine cracks), the density of the washed sand mud unfired brick will deteriorate and thus affect its various performances. It can be seen that appropriate molding pressure is a key parameter affecting the density of washed sand mud unfired bricks.

[0088] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing high-density washed sand mud unburned bricks, characterized in that: The following steps are involved: S1. Air-dry and crush the washed sand into specified specifications; S2. According to the mass ratio, measure 60-90 parts of sand washing mud, 10-30 parts of stone powder, 5-20 parts of cement, 1-5 parts of slaked lime, 0.1-1 parts of redispersible latex powder and 5-10 parts of water for use; S3. The washed sand mud, stone powder, cement, slaked lime and redispersible latex powder were mixed and dry-mixed for 4 minutes to obtain a uniform mixture; S4. Use a spray bottle to spray the weighed water into the dry mixture until the moisture content is within the range of 12% ± 0.5%. The wet mixing time is controlled within 5 minutes. S5. The moisture content of the washed sand mud unfired brick mixture is poured into the static pressure brick machine mold, the pressure of the press is controlled at 12 ± 1MPa, and the secondary static pressure method is used to obtain the washed sand mud unfired brick; S6. The obtained washed sand mud unfired bricks were placed in an environment of 23±2°C and a relative humidity of 65±15%, and cured for 28 days by covering with a film to obtain high-density washed sand mud unfired bricks, and their strength and water resistance were tested; Sand washing mud is the mud produced in the process of machine-made sand washing, with a particle size of 2mm; The effective component of the redispersible latex powder is a flexible copolymer of vinyl chloride and ethylene or a flexible terpolymer of vinyl chloride, ethylene and vinyl laurate.

2. The preparation method according to claim 1, wherein Stone powder is the stone powder collected during the ore crushing process of machine-made sand crushing equipment, with a particle size of 0.01mm~8mm.

3. The preparation method according to claim 1, wherein The cement is ordinary Portland cement.

4. The preparation method according to claim 1, wherein The calcium content of slaked lime is ≥95%, and it is a white powdery solid.

5. Application of the unburned bricks prepared by the preparation method according to any one of claims 1 to 4 in the field of construction engineering.

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