A kind of ceramsite-based porous ecological concrete and preparation method thereof

Abstract

The invention discloses a ceramsite-based porous ecological concrete, characterized in that it is made of the following raw materials in parts by weight: 300-350 parts of cement, 500-600 parts of porous ceramsite, 850-950 parts of coarse aggregate, 9-12 parts of fiber, 30-40 parts of sawdust, 30-40 parts of styrene-butadiene latex, 15-20 parts of biochar, 5-8 parts of water-absorbing resin, 100-110 parts of water, and 10-14 parts of polycarboxylic acid high-efficiency water reducing agent. Ceramsite is used to replace part of the aggregate, and the prepared concrete has high strength and good water purification effect.

Description

Technical Field

[0001] The invention relates to the technical field of ecological concrete, in particular to ceramsite-based porous ecological concrete and a preparation method thereof. Background Art

[0002] Eco-concrete is a new type of building material. It is made of coarse aggregate with larger particle size and chemical additives to enhance performance. It is prepared by special process. It has a porous structure and large specific surface area, can reduce environmental load, and can be coordinated with natural ecology and has positive significance. Due to its porous structure, it can enrich microorganisms in water bodies, purify water quality, and reduce water pollution; after filling the river bank with soil, plants can also be planted to protect the slope and fix sand, prevent soil erosion, green the slope, and restore riverbank vegetation. Therefore, ecological concrete materials can maintain the balance of the ecosystem and are of great significance for the protection of river banks and the restoration of riverbank ecology.

[0003] At present, the research on ecological slow-setting soil in China generally focuses on permeability, vegetation, mechanical properties and water purification performance. In recent years, the applicant has been committed to the research of ecological concrete. The patent document with application number 2022100225917 discloses a modified volcanic rock bio-based ecological concrete and its preparation method, which is made of the following raw materials in parts by weight: 100 parts of cement, 370-400 parts of volcanic rock, 5-6 parts of fly ash, 8-10 parts of admixture, 3-5 parts of admixture, 0.8-1.5 parts of short-cut fiber, 30-33 parts of water, and 1-1.3 parts of polycarboxylic acid water reducer. The ecological concrete uses volcanic rock as aggregate and modifies the volcanic rock to increase the water purification effect of the ecological concrete; however, the problem is that due to the large amount of aggregate used, the modification cost is high, and its mechanical properties and water purification performance need to be further improved. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a ceramsite-based porous ecological concrete to address the deficiencies in the prior art. Ceramsite is used to replace part of the aggregate, and the prepared concrete has high strength and good water purification effect.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A ceramsite-based porous ecological concrete is prepared from the following raw materials in parts by weight: 300-350 parts of cement, 500-600 parts of porous ceramsite, 850-950 parts of coarse aggregate, 9-12 parts of fiber, 30-40 parts of sawdust, 30-40 parts of styrene-butadiene emulsion, 15-20 parts of biochar, 5-8 parts of water-absorbing resin, 100-110 parts of water, and 10-14 parts of polycarboxylic acid high-efficiency water reducing agent.

[0007] Furthermore, the fiber is a mixture of polyvinyl alcohol fiber and jute fiber in a weight ratio of 1-2:1, the polyvinyl alcohol fiber has a diameter of 0.15-0.2 mm and a length of 8-10 mm, and the jute fiber has a length of 4-6 mm.

[0008] Furthermore, the jute fiber is surface treated, and the surface treatment process is: soaking the jute fiber in a 2wt% NaOH solution for 30 minutes, with a solid-liquid ratio of 1:2-3, washing and drying for later use.

[0009] Furthermore, the porous ceramsite comprises an inner core and a coating layer, and is prepared by the following steps:

[0010] (1) The inner core and the coating layer have the same ingredients, and are made of the following raw materials in parts by weight: 32-36 parts of red mud, 28-32 parts of fly ash, 8-12 parts of sawdust, 9-12 parts of glass fiber, 4-5 parts of coal powder, 2-3 parts of calcium carbonate whiskers, 4-6 parts of activated alumina, and 2-3 parts of dextrin; the particle size of the coal powder in the ingredients of the inner core is 70-150 μm, and the particle size of the coal powder in the ingredients of the coating layer is 50-70 μm;

[0011] (2) After the ingredients of the inner core are mixed evenly, 25-30wt% of water is added to granulate to prepare an inner core green body, and then the ingredients of the coating layer and 25-30wt% of water are added to continue granulation to make a raw ball, which is then dried;

[0012] (3) Heat to 1200℃ and fire for 15-20min, then cool in the furnace;

[0013] (4) The fired product is immersed in a 2wt% NaOH solution, kept at 80°C for 1-1.5h, and then washed and dried to obtain the product.

[0014] Furthermore, in the step (2), the particle size of the inner core green body is 8-10 mm, and the particle size of the green ball obtained by adding the coating layer ingredients and continuing granulation is 15-20 mm.

[0015] Furthermore, in step (3), the steel is pre-fired at 400-450°C for 15-20 min, and then heated to 1200°C and fired for 15-20 min, with a heating rate of 5-10°C / min.

[0016] A method for preparing ceramsite-based porous ecological concrete comprises the following steps:

[0017] After the porous ceramsite and coarse aggregate are mixed, one-third of water is added to wet the surface, and then sawdust, biochar, absorbent resin and fiber are added and mixed for 2-3 minutes; then the remaining raw materials are added and mixed for 2 minutes, injected into a mold, vibrated and formed, and cured; the porous ceramsite is soaked in water for 24 hours before use.

[0018] The beneficial effects of the present invention are:

[0019] 1. The present invention discloses a ceramsite-based porous ecological concrete, which replaces part of the aggregate with the ceramsite developed by the applicant, and then adds fiber, sawdust, styrene-butadiene emulsion, biochar and water-absorbing resin to prepare the ecological concrete. The ecological concrete has high strength, a compressive strength of 23.7-27.5Mpa, and a high removal rate of N, P and COD, and an excellent water purification effect.

[0020] 2. The present application is porous concrete with high porosity. In order to increase the strength and toughness of concrete, polyvinyl alcohol fiber and jute fiber are added. The polyvinyl alcohol fiber has good bonding performance with the concrete matrix. The compound natural jute fiber, unlike artificial fiber, generates very little static electricity. Mixing with polyvinyl alcohol fiber can reduce fiber agglomeration. Moreover, after the jute fiber of the present application is soaked in alkali solution, the aspect ratio of the jute fiber is increased, and the bonding force with cement slurry is strong, which has the effect of strengthening and toughening, and also has a certain water retention property, which can further increase the water purification effect.

[0021] In addition, a small amount of sawdust, biochar and absorbent resin are added to the raw materials and dispersed in the concrete matrix. On the one hand, it enhances the adsorption and water purification performance of the concrete, and it also has certain water retention properties, which can increase the surface adhesion of the concrete, help microbial bonding, and increase the water purification effect.

[0022] 3. The porous expanded clay used in this application has a two-layer structure, which is divided into an inner core and a coating layer. The matrix is ​​mainly prepared from red mud, fly ash, sawdust, coal powder, glass fiber, calcium carbonate whiskers, activated alumina and dextrin. The particle size of the coating layer coal powder is smaller than that of the inner layer, which can increase the residence time of the water body, increase the adsorption performance and water purification performance.

[0023] Both red mud and fly ash contain a large amount of silicon oxide and aluminum oxide. Glass fiber and activated alumina are also added, which are evenly distributed in the matrix to fill the gaps, promote sintering, and increase the density of the matrix. Calcium carbonate whiskers, coal powder and dextrin are also added. Dextrin is used as a binder in the early stage to increase the bonding performance of the raw material. In the heating stage, it begins to slowly carbonize and produce uniform micropores in the matrix. The particle size of coal powder gradually decreases from the inner core to the outer layer, and after high-temperature roasting, a gradually decreasing pore structure is formed. A small amount of calcium carbonate whiskers synergizes with coal powder and dextrin to form small and evenly distributed interconnected gaps in the porous ceramsite, which helps to increase water retention. Moreover, these components have different decomposition temperatures, which can ensure uniform and slow pore formation and matrix strength. In addition, a small amount of sawdust is added, which has a strong adsorption effect after carbonization, further increasing the water purification performance.

[0024] 4. The porous expanded clay is first fired at a low temperature and then heated up, which can control the slow volatilization of moisture and gas in the matrix to ensure strength. After firing, the porous expanded clay is hydrothermally kept warm in an alkaline solution to dissolve the silicon and aluminum on the surface and cracks of the porous expanded clay, and then undergo condensation reaction, nucleation, and growth under alkaline conditions, making the surface and cracks of the porous expanded clay rougher and having a certain strength, which is conducive to the attachment of microorganisms and biofilm, further increasing the water purification effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the water retention performance test curve of porous ceramsite for this application. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. Example 1

[0027] A ceramsite-based porous ecological concrete is made of the following raw materials in parts by weight: 300 parts of PC42.5 cement, 500 parts of porous ceramsite, 850 parts of coarse aggregate, 9 parts of fiber, 30 parts of wood chips, 30 parts of styrene-butadiene emulsion (solid content 48%), 15 parts of biochar, 5 parts of water-absorbing resin, 100 parts of water, and 10 parts of polycarboxylic acid high-efficiency water reducing agent.

[0028] The fibers are polyvinyl alcohol fibers and jute fibers mixed in a weight ratio of 1:1. The polyvinyl alcohol fibers have a diameter of 0.15-0.2 mm and a length of 8-10 mm, and the jute fibers have a length of 4-6 mm.

[0029] The jute fiber is surface treated before use. The specific surface treatment process is: cut the jute plant fiber into 4-6 mm small segments, soak it in 2wt% NaOH solution for 30 minutes, with a solid-liquid ratio of 1:2, wash and dry it for use.

[0030] The water-absorbing resin used in this application is a commercially available super absorbent resin (SPA) with a particle size of 0.15 mm and a water absorption rate of 80-100. The main components of red mud are: Fe 2 O 3 30-33wt%,Al 2 O 3 20-25wt%,SiO 2 15-18 wt%, CaO15-20wt%, Na 2 O10-12wt%; the main components of fly ash are: SiO 2 50-55wt%,Al 2 O 3 35-40wt%,Fe 2 O 3 2-3wt%; The main component of glass fiber is SiO 2、Al 2 O 3 , calcium oxide, etc.; the coarse aggregate is limestone crushed stone, with an apparent density of 2690kg / m 3 , bulk density 1500 kg / m 3 The crushing index is 8.9%, the particle size is 15-30mm; the biochar particle size is 1-3mm.

[0031] The porous ceramsite comprises an inner core and a coating layer, and is prepared by the following steps:

[0032] (1) The inner core of the porous ceramsite has the same ingredients as the coating layer, and is made of the following raw materials in parts by weight: 32 parts of red mud, 32 parts of fly ash, 8 parts of sawdust, 9 parts of glass fiber, 4 parts of coal powder, 2 parts of calcium carbonate whiskers, 4 parts of activated alumina and 2 parts of dextrin; the particle size of the coal powder in the inner core is 70-150 μm, and the particle size of the coal powder in the coating layer is 50-70 μm, wherein 25-30 wt% of water by weight of the raw materials needs to be added during granulation;

[0033] (2) After the ingredients of the inner core are mixed evenly, 25 wt% of water is added to granulate to prepare an inner core green body with a particle size of 8 mm, and then the ingredients of the coating layer and the mixture of 25 wt% of water are added to continue granulation to prepare a raw material ball with a particle size of 15 mm, which is then dried;

[0034] (3) Pre-sinter at 400°C for 20 min, then heat to 1200°C for 20 min at a heating rate of 5°C / min, and cool with the furnace;

[0035] (4) The fired product is immersed in a 2wt% NaOH solution with a solid-liquid ratio of 1:3, kept at 80°C for 1-1.5h, and then washed and dried to obtain the product.

[0036] A method for preparing ceramsite-based porous ecological concrete comprises the following steps:

[0037] After the porous ceramsite and coarse aggregate are mixed, one-third of water is added to wet the surface, and then sawdust, biochar, absorbent resin and fiber are added and mixed for 2 minutes; then the remaining raw materials are added and mixed for 2 minutes, injected into a mold, vibrated and formed, and cured; the porous ceramsite is soaked in water for 24 hours before use to make it saturated with water before being used to prepare concrete. Example 2

[0038] A ceramsite-based porous ecological concrete is prepared from the following raw materials in parts by weight: 310 parts of cement, 520 parts of porous ceramsite, 880 parts of coarse aggregate, 10 parts of fiber, 32 parts of sawdust, 32 parts of styrene-butadiene emulsion, 16 parts of biochar, 6 parts of water-absorbing resin, 105 parts of water, and 11 parts of polycarboxylic acid high-efficiency water reducing agent.

[0039] The fiber is a mixture of polyvinyl alcohol fiber and jute fiber in a weight ratio of 1:1. The polyvinyl alcohol fiber has a diameter of 0.15-0.2 mm and a length of 8-10 mm, and the jute fiber has a length of 4-6 mm.

[0040] The jute fiber is surface treated, and the surface treatment process is: cutting the jute plant fiber into small segments of 4-6 mm, soaking in a 2wt% NaOH solution for 30 minutes, with a solid-liquid ratio of 1:2, washing and drying for standby use.

[0041] The porous ceramsite comprises an inner core and a coating layer, and is prepared by the following steps:

[0042] (1) The porous ceramsite inner core and the coating layer have the same ingredients, and are made of the following raw materials in parts by weight: 33 parts of red mud, 32 parts of fly ash, 9 parts of sawdust, 10 parts of glass fiber, 4.2 parts of coal powder, 2.2 parts of calcium carbonate whiskers, 4.5 parts of activated alumina and 2.2 parts of dextrin; the particle size of the coal powder in the inner core is 70-150 μm, and the particle size of the coal powder in the coating layer is 50-70 μm;

[0043] (2) After the inner core ingredients are evenly mixed, 28 wt% of water is added to prepare an inner core green body with a particle size of 8 mm, and then the coating layer ingredients and 28 wt% of water are added to continue granulation to prepare a raw material ball with a particle size of 15 mm, which is then dried;

[0044] (3) Pre-sinter at 450°C for 15 min, then heat to 1200°C for 20 min at a heating rate of 5°C / min, and cool with the furnace;

[0045] (4) The fired product is immersed in a 2wt% NaOH solution with a solid-liquid ratio of 1:3, kept at 80°C for 1-1.5h, and then washed and dried to obtain the product.

[0046] A method for preparing ceramsite-based porous ecological concrete comprises the following steps:

[0047] After the porous ceramsite and coarse aggregate are mixed, one-third of water is added to wet the surface, and then wood chips, biochar, absorbent resin and fiber are added and mixed for 3 minutes; then the remaining raw materials are added and mixed for 2 minutes, injected into a mold, vibrated and formed, and cured; the porous ceramsite is soaked in water for 24 hours before use. Example 3

[0048] A ceramsite-based porous ecological concrete is prepared from the following raw materials in parts by weight: 320 parts of cement, 550 parts of porous ceramsite, 900 parts of coarse aggregate, 11 parts of fiber, 35 parts of sawdust, 35 parts of styrene-butadiene emulsion, 18 parts of biochar, 6.5 parts of water-absorbing resin, 105 parts of water, and 12 parts of polycarboxylic acid high-efficiency water reducing agent.

[0049] The fiber is a mixture of polyvinyl alcohol fiber and jute fiber in a weight ratio of 1.5:1. The polyvinyl alcohol fiber has a diameter of 0.15-0.2 mm and a length of 8-10 mm, and the jute fiber has a length of 4-6 mm.

[0050] The jute fiber is surface treated, and the surface treatment process is: cutting the jute plant fiber into 4-6 mm small segments, soaking in 2wt% NaOH solution for 30 minutes, with a solid-liquid ratio of 1:3, washing and drying for standby use.

[0051] The porous ceramsite comprises an inner core and a coating layer, and is prepared by the following steps:

[0052] (1) The porous ceramsite inner core and the coating layer have the same ingredients, and are made of the following raw materials in parts by weight: 35 parts of red mud, 30 parts of fly ash, 10 parts of sawdust, 11 parts of glass fiber, 4.5 parts of coal powder, 2.5 parts of calcium carbonate whiskers, 5 parts of activated alumina and 2.5 parts of dextrin; the particle size of the coal powder in the inner core is 70-150 μm, and the particle size of the coal powder in the coating layer is 50-70 μm;

[0053] (2) After the inner core ingredients are evenly mixed, 25 wt% water is added to prepare an inner core green body with a particle size of 8 mm, and then the coating layer ingredients and the mixture of 25 wt% water are added to continue granulation to prepare a raw material ball with a particle size of 15 mm, which is then dried;

[0054] (3) Pre-sinter at 450°C for 15 min, then heat to 1200°C for 15 min at a heating rate of 5°C / min, and cool with the furnace;

[0055] (4) The fired product is immersed in a 2wt% NaOH solution with a solid-liquid ratio of 1:3, kept at 80°C for 1-1.5h, and then washed and dried to obtain the product.

[0056] The other processes are the same as those in Example 1. Example 4

[0057] A ceramsite-based porous ecological concrete is prepared from the following raw materials in parts by weight: 340 parts of cement, 580 parts of porous ceramsite, 920 parts of coarse aggregate, 12 parts of fiber, 38 parts of wood chips, 38 parts of styrene-butadiene emulsion, 19 parts of biochar, 7 parts of water-absorbing resin, 108 parts of water, and 13 parts of polycarboxylic acid high-efficiency water reducing agent.

[0058] The fiber is a mixture of polyvinyl alcohol fiber and jute fiber in a weight ratio of 2:1. The polyvinyl alcohol fiber has a diameter of 0.15-0.2 mm and a length of 8-10 mm, and the jute fiber has a length of 4-6 mm.

[0059] The jute fiber is surface treated, and the surface treatment process is: cutting the jute plant fiber into 4-6 mm small segments, soaking in 2wt% NaOH solution for 30 minutes, with a solid-liquid ratio of 1:3, washing and drying for standby use.

[0060] The porous ceramsite comprises an inner core and a coating layer, and is prepared by the following steps:

[0061] (1) The ingredients of the porous ceramsite inner core and the coating layer are the same, and the ingredients are made of the following raw materials in parts by weight: 36 parts of red mud, 28 parts of fly ash, 11 parts of sawdust, 12 parts of glass fiber, 4.5 parts of coal powder, 2.5 parts of calcium carbonate whiskers, 5.5 parts of activated alumina and 2.5 parts of dextrin; the particle size of the coal powder in the ingredients of the inner core is 70-150 μm, and the particle size of the coal powder in the ingredients of the coating layer is 50-70 μm;

[0062] (2) After the inner core ingredients are evenly mixed, 25 wt% water is added to prepare the inner core with a particle size of 8 mm, and then the coating layer ingredients and a mixture of 25 wt% water are added to continue granulation to prepare raw material balls with a particle size of 15 mm, which are then dried;

[0063] (3) Pre-sinter at 450°C for 18 min, then heat to 1200°C for 18 min at a heating rate of 5°C / min, and cool with the furnace;

[0064] (4) The fired product is immersed in a 2wt% NaOH solution with a solid-liquid ratio of 1:3, kept at 80°C for 1-1.5h, and then washed and dried to obtain the product.

[0065] The other processes are the same as those in Example 1. Example 5

[0066] A ceramsite-based porous ecological concrete is prepared from the following raw materials in parts by weight: 350 parts of cement, 600 parts of porous ceramsite, 950 parts of coarse aggregate, 12 parts of fiber, 40 parts of wood chips, 40 parts of styrene-butadiene emulsion, 20 parts of biochar, 8 parts of water-absorbing resin, 110 parts of water, and 14 parts of polycarboxylic acid high-efficiency water reducing agent.

[0067] The fiber is a mixture of polyvinyl alcohol fiber and jute fiber in a weight ratio of 1.5:1. The polyvinyl alcohol fiber has a diameter of 0.15-0.2 mm and a length of 8-10 mm, and the jute fiber has a length of 4-6 mm.

[0068] The jute fiber is surface treated, and the surface treatment process is: cut the jute plant fiber into small segments of 4-6 mm, soak it in 2wt% NaOH solution for 30 minutes, with a solid-liquid ratio of 1:2.5, wash it with water, and dry it for use.

[0069] The porous ceramsite comprises an inner core and a coating layer, and is prepared by the following steps:

[0070] (1) The ingredients of the porous ceramsite inner core and the coating layer are the same, and the ingredients are made of the following raw materials in parts by weight: 35 parts of red mud, 28 parts of fly ash, 12 parts of sawdust, 10 parts of glass fiber, 5 parts of coal powder, 3 parts of calcium carbonate whiskers, 6 parts of activated alumina and 3 parts of dextrin; the particle size of the coal powder in the ingredients of the inner core is 70-150 μm, and the particle size of the coal powder in the ingredients of the coating layer is 50-70 μm;

[0071] (2) After the inner core ingredients are evenly mixed, 25 wt% water is added to prepare the inner core with a particle size of 8 mm, and then the coating layer ingredients and the mixture of 25 wt% water are added to continue granulation to prepare raw material balls with a particle size of 15 mm, which are then dried;

[0072] (3) Pre-sinter at 400°C for 20 min, then heat to 1200°C for 20 min at a heating rate of 5°C / min, and cool with the furnace;

[0073] (4) The fired product is immersed in a 2wt% NaOH solution with a solid-liquid ratio of 1:3, kept at 80°C for 1-1.5h, and then washed and dried to obtain the product.

[0074] The other processes are the same as those in Example 1.

[0075] Comparative Example 1

[0076] Comparative Example 1 is to replace the porous ceramsite in the raw material of the ecological concrete in Example 5 with crushed stone, and the other processes are the same as those in Example 5.

[0077] Comparative Example 2

[0078] The difference between Comparative Example 2 and Example 5 is that there is no stratified granulation.

[0079] The porous ceramsite is prepared by the following steps:

[0080] (1) The batch is made of the following raw materials in parts by weight: 35 parts of red mud, 28 parts of fly ash, 12 parts of sawdust, 10 parts of glass fiber, 5 parts of coal powder, 3 parts of calcium carbonate whiskers, 6 parts of activated alumina and 3 parts of dextrin; the particle size of the coal powder in the batch is 50-70 μm;

[0081] (2) After the ingredients are evenly mixed, 25 wt% water is added to prepare raw material balls with a particle size of 15 mm, and then dried;

[0082] (3) Pre-sinter at 400°C for 20 min, then heat to 1200°C for 20 min at a heating rate of 5°C / min, and cool with the furnace;

[0083] (4) The fired product is immersed in a 2wt% NaOH solution with a solid-liquid ratio of 1:3, kept at 80°C for 1-1.5h, and then washed and dried to obtain the product.

[0084] The other processes are the same as those in Example 5.

[0085] Comparative Example 3

[0086] The difference between Comparative Example 3 and Example 5 is that the calcium carbonate whiskers in the porous ceramsite batch are replaced by coal powder.

[0087] Comparative Example 4

[0088] The difference between Comparative Example 4 and Example 5 is:

[0089] The preparation process of the porous ceramsite omits step (4), and the finished product is obtained after cooling in the furnace without undergoing alkaline solution hydrothermal treatment.

[0090] Performance Testing

[0091] 1. Detect the porosity and compressive strength (MPa) of the porous ceramsite prepared in Examples 1-5 and Comparative Examples 1-4;

[0092] 2. The water retention performance of the porous ceramsite prepared in Examples 1-5 and Comparative Examples 1-4 was tested. The specific test method was: the porous ceramsite was immersed in water for 24 hours (the mass difference before and after water infiltration was the water absorption), and then dried at a humidity of 45% and 50°C. The water loss rate was calculated by weighing at regular intervals until it was dried to a constant weight. The test results are shown in Figure 1 .

[0093] 3. The concretes of Examples 1-5 and Comparative Examples 1-4 were respectively made into ecological concrete test blocks of standard size of 150*150*150 mm and cured to 28 days in accordance with the standard, and their compressive strength (MPa), porosity and water purification performance were tested.

[0094] 4. Static water purification test: nine groups of test blocks with a size of 150*150*150mm were placed in seven drums filled with sewage, with a total of 20L of sewage. The test drums were placed in a ventilated indoor environment. The total nitrogen, CODcr content and total phosphorus concentration were tested before and after the test, and the average removal rate was calculated. The test time was 720h. The test results are shown in Table 1.

[0095] Table 1 Concrete properties and water purification test results

[0096]

[0097] Depend on Figure 1It can be seen that the porous ceramsite prepared in Examples 1-5 of the present application has excellent water retention performance, and the water retention time is 51-54h, indicating that the porous ceramsite prepared has many interconnected microporous structures, which can achieve slow evaporation and release of water; while the water retention time of Example 5 is slightly lower than that of other embodiments, which may be due to the high porosity of Example 5 and the rapid evaporation of water, resulting in a decrease in water retention performance. The water retention time of Comparative Examples 2-4 is lower than that of Example 5. It can be seen that the particle size of the coating layer coal powder is smaller than the particle size of the inner layer, and the calcium carbonate whiskers and other porogens in the porous ceramsite work together to form small and evenly distributed interconnected voids in the porous ceramsite, as well as hydrothermal treatment in alkali solution after firing, which can increase water retention performance and correspondingly increase the water purification effect.

[0098] It can be seen from Table 1 that the porosity of the ceramsite prepared in the present application is 50.4-56.1%, which is a porous structure, and the strength is relatively high, with a compressive strength of 5.6-6.7 MPa; wherein the porous ceramsite in Comparative Example 4 is not treated with alkali solution after firing, and its porosity is slightly lower than that of Example 5, and its strength is much lower than that of Example 5, indicating that hydrothermal insulation in alkali solution after firing can play a role in internal strengthening and toughening.

[0099] The prepared ecological concrete has a compressive strength of 24.7-27.5Mpa. Through a static water purification test, its nitrogen removal rate is 86-88%, phosphorus removal rate is 86-89%, CODcr removal rate is 90-92.5%, and its water purification performance is excellent.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A ceramsite-based porous ecological concrete, Features: It is made of the following raw materials in parts by weight: 300-350 parts of cement, 500-600 parts of porous ceramsite, 850-950 parts of coarse aggregate, 9-12 parts of fiber, 30-40 parts of sawdust, 30-40 parts of styrene-butadiene emulsion, 15-20 parts of biochar, 5-8 parts of water-absorbing resin, 100-110 parts of water, and 10-14 parts of polycarboxylic acid high-efficiency water reducing agent; The porous ceramsite comprises an inner core and a coating layer, and is prepared by the following steps: (1) The inner core and the coating layer have the same ingredients, and are made of the following raw materials in parts by weight: 32-36 parts of red mud, 28-32 parts of fly ash, 8-12 parts of sawdust, 9-12 parts of glass fiber, 4-5 parts of coal powder, 2-3 parts of calcium carbonate whiskers, 4-6 parts of activated alumina, and 2-3 parts of dextrin; the particle size of the coal powder in the ingredients of the inner core is 70-150 μm, and the particle size of the coal powder in the ingredients of the coating layer is 50-70 μm; (2) After the ingredients of the inner core are mixed evenly, 25-30wt% of water is added to granulate to prepare an inner core green body, and then the ingredients of the coating layer and 25-30wt% of water are added to continue granulation to make a raw ball, which is then dried; (3) Heat to 1200℃ and fire for 15-20min, then cool in the furnace; (4) The fired product is immersed in a 2wt% NaOH solution, kept at 80°C for 1-1.5h, and then washed and dried to obtain the product.

2. The ceramsite-based porous ecological concrete according to claim 1, Features: The fiber is a mixture of polyvinyl alcohol fiber and jute fiber in a weight ratio of 1-2:

1. The polyvinyl alcohol fiber has a diameter of 0.15-0.2 mm and a length of 8-10 mm, and the jute fiber has a length of 4-6 mm.

3. The ceramsite-based porous ecological concrete according to claim 2, Features: The jute fiber is surface treated, and the surface treatment process is: soaking the jute fiber in a 2wt% NaOH solution for 30 minutes, with a solid-liquid ratio of 1:2-3, washing and drying for later use.

4. The ceramsite-based porous ecological concrete according to claim 1, Features: In the step (2), the particle size of the inner core green body is 8-10 mm, and the particle size of the green ball is 15-20 mm.

5. The ceramsite-based porous ecological concrete according to claim 1, Features: In the step (3), the steel is first pre-fired at 400-450°C for 15-20 minutes, and then heated to 1200°C and fired for 15-20 minutes, with a heating rate of 5-10°C / min.

6. A method for preparing the ceramsite-based porous ecological concrete according to claim 1, The following steps are involved: After mixing the porous expanded clay and coarse aggregate, add one-third of water to wet the surface, then add sawdust, biochar, absorbent resin and fiber and mix for 2-3 minutes; then add the remaining raw materials and mix for 2 minutes, inject into the mold, vibrate and shape, and cure.

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