Phytogenic concrete precast block with water purification function and preparation method thereof

Abstract

The application provides a phytogenic concrete precast block with a water purification function and a preparation method thereof, which comprises the following raw materials in parts by mass: cement 80-100 parts, volcanic rock 300-400 parts, silica stone 100-200 parts, diatomite 15-30 parts, plant fiber 0.5-1.5 parts, water 25-35 parts, silica ash 2.5-3.5 parts, sodium alginate 1-3 parts, cationic starch 0.5-1.5 parts and water reducing agent 1-3 parts; and carbon curing is performed on the concrete precast block after demolding. The phytogenic concrete precast block prepared by the application has the advantages of high strength, good air and water permeability, remarkable water purification function, low alkalinity and good biocompatibility.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of building materials, and particularly relates to a phytogenic concrete prefabricated block with water purification function and a preparation method thereof. BACKGROUND

[0002] Phytogenic concrete is a new multifunctional ecological slope protection, which, compared with the previous one, only needs to bear the reinforcement and water flow scouring of the river bank, now the slope protection emphasizes more on the embodiment of its ecological value. Unlike the traditional slope protection, it uses large-pore concrete as the skeleton and plants slope protection grass on it. The organic combination of concrete and plants makes it have good water purification capacity, ecological environment restoration effect and ecological environment combination capacity, solving the problems of large resource consumption, poor water pollutant reduction performance and ecological environment combination capacity of the traditional slope protection.

[0003] The water purification capacity of conventional phytogenic concrete mainly depends on plants, and a more serious water pollution environment can limit the growth of plants, and most plants die in winter. Therefore, plants cannot completely bear the heavy task of water purification. This leads to the fact that the water purification capacity of phytogenic concrete depends on the environment and season. Therefore, how to strengthen the water purification capacity of phytogenic concrete itself has become an important issue to be solved in the application research of phytogenic concrete.

[0004] Another problem that needs to be concerned in the application of phytogenic concrete is the coordination problem between strength and porosity. Phytogenic concrete requires large pores and high porosity to ensure good air permeability and water permeability suitable for plant growth. However, large pores and high porosity can cause low concrete strength and poor durability. SUMMARY

[0005] The present application provides a phytogenic concrete prefabricated block with water purification function and a preparation method thereof, which has the characteristics of high strength, large porosity, significant water purification effect, good ecological compatibility, etc.

[0006] The technical scheme of the present application is a phytogenic concrete prefabricated block with water purification function, which comprises the following raw materials in parts by mass: ordinary Portland cement 80-100 parts, volcanic rock 300-400 parts, silica stone 100-200 parts, diatomite 15-30 parts, plant fiber 0.5-1.5 parts, water 25-35 parts, silica fume 2.5-3.5 parts, sodium alginate 1-3 parts, cationic starch 0.5-1.5 parts and water reducing agent 1-3 parts; the concrete prefabricated block is carbon cured after demolding.

[0007] Further, the ordinary Portland cement has a Blaine specific surface area of 450 m 2The strength grade of the general portland cement is 42.5 or above, preferably slag portland cement or fly ash portland cement.

[0008] Further, the volcanic rock has a particle size of 10-20 mm, a porosity of ≥40%, a crushing value of ≤15% and a powder content of ≤3%.

[0009] Further, the silica has a particle size of 10-20 mm, a SiO2 mass content of ≥95% and a crushing value of ≤15%.

[0010] Further, the diatomite has a SiO2 mass content of ≥85%, a water content of ≤5% and a mesh number of ≥300.

[0011] Further, the plant fiber has a length of 10-20 mm and is a bast fiber such as flax or bamboo fiber.

[0012] Further, the silica fume has a Blaine specific surface area of 20000-30000 m2 / g. 2 Further, the silica fume has a SiO2 mass content of ≥85%.

[0013] Further, the water reducing agent is a polycarboxylic acid water reducing agent.

[0014] Further, the carbon curing is performed at a carbon dioxide volume concentration of ≥30%, a relative humidity of 60-70% and a temperature of 20±2℃.

[0015] The present application also relates to a preparation method of the concrete precast block, comprising the following steps:

[0016] S1, the raw materials are weighed according to the proportion, the general portland cement, diatomite, plant fiber, silica fume, sodium alginate and cationic starch are uniformly mixed, then water and a water reducing agent are uniformly mixed, finally, the volcanic rock and the silica are uniformly mixed to obtain a mixture;

[0017] S2, the mixture obtained in S1 is spread and formed in a mold, demolded after conventional indoor curing, and finally carbon cured to obtain the phytogenic concrete precast block with water purification function.

[0018] The present application has the following advantages:

[0019] (1) High strength. The vegetation concrete is sand-free, has large pores, high porosity, and fewer connecting surfaces between coarse aggregates, and thus the strength is low. The present application uses volcanic rock as the main coarse aggregate, which has the characteristics of high strength, high wear resistance, and high hardness, which is beneficial to the strength improvement of the vegetation concrete precast block. Second, the volcanic rock and silica have large specific surface areas, rough and angular surfaces, which increase the connecting area of the cement paste between the aggregates, which is beneficial to the strength improvement of the vegetation concrete precast block. Third, the present application also adds silica fume, which has small particles and can effectively fill the pores of hardened cement stone, i.e. the hardened cement paste at the connecting surface of the coarse aggregate is more dense, which is beneficial to the strength improvement of the vegetation concrete precast block. Fourth, the main components of silica fume and diatomite are SiO2, which can undergo secondary hydration reaction with the cement hydration products to form calcium silicate gel, thereby improving the strength of the vegetation concrete precast block. Fifth, after demolding, carbon curing is used, which causes the dissolved carbon dioxide in the liquid phase to react with the alkaline substances such as calcium ions and magnesium ions in the cement paste, and at the same time participate in the hydration reaction of the cementitious material. The main components of the hardened cement paste after hardening are ettringite phase, carbonate, carbon aluminates, and part of low calcium-silicon ratio hydrated calcium silicate gel, and the number of crystals is much higher than that in the hardened cement paste in conventional vegetation concrete, thereby improving the strength of the vegetation concrete precast block. Finally, the addition of plant fibers can strengthen the interface of each phase of the concrete, inhibit the generation and expansion of microcracks, and help to improve the strength of the vegetation concrete precast block.

[0020] (2) Good air and water permeability. In addition to the designed porosity of the vegetation concrete precast block, the volcanic rock used as the coarse aggregate has the characteristics of large specific surface area, high porosity (the pore volume accounts for not less than 40% of the total volume), and good particle shape, which improves the air and water permeability of the vegetation concrete. Similarly, the porous structure of silica also improves the air and water permeability of the vegetation concrete precast block.

[0021] (3) Significant water purification function. In addition to the water purification function of plants, the volcanic rock has a large specific surface area and high porosity, which can adsorb harmful bacteria and heavy metal ions in water that affect living organisms, and even some residual chlorine in water; silica has a porous structure and light weight, and has strong adsorption capacity; diatomite has a porous structure, is acid-resistant, has large pore volume and pore size, and has large specific surface area and strong adsorption capacity; which significantly improves the water purification function of the vegetation concrete precast block.

[0022] (4) Low alkalinity. First, the high porosity structure of the vegetation concrete precast block and each raw material, especially the composition of the cementitious material and the porous characteristics of the volcanic rock and silica as aggregate, are all conducive to the implementation effect of carbon curing, realizing the low alkalinity of the vegetation concrete precast block; carbon curing will cause the alkaline substances of the vegetation concrete precast block to mineralize with the carbon dioxide dissolved in water to generate carbonates; at the same time, the carbon dioxide dissolved in water also participates in the hydration reaction of the cementitious material, which is superimposed with the hydration reaction to generate carbon aluminates and other substances, i.e. the mineralization reaction products and the intermediate products of the mineralization reaction all participate in the hydration reaction of the cementitious material; after hardening, the main composition of the cement paste is ettringite phase, carbonate, carbon aluminates crystals and part of low calcium-silicon ratio hydrated calcium silicate gel, and the alkalinity of the vegetation concrete precast block is significantly reduced; the water generated when calcium carbonate and magnesium carbonate are formed can also participate in the hydration reaction of the cementitious material, playing a self-curing role. Second, the porous structure of the volcanic rock and silica, large specific surface area, is conducive to the secondary hydration reaction of silica fume and diatomite with the cement hydration products to form low calcium-silicon ratio hydrated calcium silicate gel, i.e. low alkalinity hydrated calcium silicate gel, which is also conducive to reducing the alkalinity of the vegetation concrete precast block. Finally, the volcanic rock can stabilize the pH value, which can adjust the excessively acidic or excessively alkaline water to near neutral, thereby improving the alkaline environment for plant growth.

[0023] (5) Good biocompatibility. The trace elements adsorbed by the volcanic rock, silica and diatomite from the water can be absorbed by the root system of the plants, thereby promoting the growth of the plants; the diatomite can also play a role in moisturizing and prolonging the effect time of the medicine and fertilizer, and assisting the growth of crops; sodium alginate, as a natural polysaccharide carbohydrate with a relatively low price, has the characteristics of non-toxicity, good biocompatibility and good biological regenerability.

[0024] (6) Light quality. The coarse aggregate, which accounts for a major part of the quality of the vegetation concrete, is volcanic rock and silica, and both of these two stone materials have the characteristic of light quality, so the light quality vegetation concrete is more convenient to operate compared with the conventional vegetation concrete, and can be applied to projects with requirements on the unit weight.

[0025] (7) From the aspects of material composition, structure, preparation method and application, the green development concept of building materials is implemented, and helps to realize the "double carbon" target. Environment-friendly materials such as slag portland cement, fly ash portland cement and plant fibers are selected in the material composition, the structural characteristics of the volcanic rock and silica are utilized, the carbon curing method is adopted in the preparation, carbon dioxide can be effectively utilized, and the plants grown in the application can absorb and utilize carbon dioxide in the environment. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The volcanic rock used in the present application is shown.

[0027] Figure 2 The silica used in the present application is shown. DETAILED DESCRIPTION

[0028] The embodiments of the present application will be described in detail below with examples, but those skilled in the art will understand that the following examples are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application.

[0029] Example 1

[0030] A phytogenic concrete prefabricated block with water purification function comprises the following raw materials in mass fraction:

[0031] 42.5 strength grade slag portland cement 90 parts, Blaine specific surface area 460 m 2 / kg;

[0032] Volcanic rock 400 parts, porosity 42%, crushing value index 13%, powder content 2%, particle size 10-20 mm;

[0033] Silica 100 parts, SiO2content 96% (mass percentage), crushing value index 12%, particle size 10-20 mm;

[0034] 350 mesh diatomite 20 parts, SiO2content 86% (mass percentage), water content 2%;

[0035] Flax fiber 1 part, length 15-20 mm;

[0036] Water 30 parts;

[0037] Silica fume 3 parts, Blaine specific surface area 22000 m 2 / kg, SiO2content 90% (mass percentage);

[0038] Sodium alginate 2 parts;

[0039] Cationic starch 1 part;

[0040] Polycarboxylic acid water reducing agent 2 parts.

[0041] A preparation method of a phytogenic concrete prefabricated block with water purification function comprises the following steps:

[0042] Step one, weighing: weigh the cement, volcanic rock, silica, diatomite, flax fiber, water, silica fume, sodium alginate, cationic starch, and polycarboxylic acid water reducing agent with the set mixing ratio.

[0043] Step two, mixing: first, the cement, silica, flax fiber, silica fume, sodium alginate, cationic starch of step one are weighed and added into the mixer in turn and stirred for 2 minutes; then the water and water reducing agent of step one are weighed and added into the mixer and stirred for another 2 minutes to form a uniform slurry with appropriate consistency; finally, the pumice and silica of step one are weighed and added into the mixer and stirred for another 3 minutes to form a uniform mixture, and the mixture is discharged.

[0044] Step three, paving and forming: the mixture of step two is evenly layered and paved in the mold.

[0045] Step four, standard curing: the mixture of step three is placed in the curing chamber together with the mold and cured for 3 days, the temperature of the curing chamber is controlled at 20±2℃, and the relative humidity is greater than 95%.

[0046] Step five, demolding: the vegetation concrete is separated from the mold to obtain vegetation concrete precast blocks; the precast blocks are placed in the carbon curing chamber with a distance of 100-500mm between adjacent precast blocks.

[0047] Step six, carbon curing: the vegetation concrete precast blocks are cured in the carbon curing chamber for 28 days, the volume concentration of carbon dioxide in the chamber is not less than 30%, the relative humidity is 60-70%, and the temperature is 20±2℃.

[0048] Step seven, finished product, quality inspection, and stacking: the vegetation concrete precast blocks are removed from the carbon curing chamber, and the finished product is obtained after the quality inspection meets the requirements, and the finished product is stacked.

[0049] Example 2

[0050] A vegetation concrete precast block with water purification function, comprising the following mass fractions of raw materials:

[0051] 42.5 strength grade slag Portland cement 90 parts, Blaine specific surface area 460 m 2 / kg;

[0052] Pumice 350 parts, porosity 42%, crushing value index 13%, powder content 2%, particle size 10-20 mm;

[0053] Silica 150 parts, SiO2 content 96% (mass percent), crushing value index 12%, particle size 10-20 mm;

[0054] 400 mesh diatomite 20 parts, SiO2 content 90% (mass percent), water content 3%;

[0055] Flax fiber 1 part, length 15-20 mm;

[0056] Water 30 parts;

[0057] silica fume 3 parts, Blaine specific surface area 26000 m 2 / kg, SiO2 content 95% (mass percent);

[0058] sodium alginate 2 parts;

[0059] cationic starch 1 part;

[0060] polycarboxylic acid water reducing agent 2 parts.

[0061] A method for preparing a phytogenic concrete precast block with water purification function is the same as that in Example 1.

[0062] Example 3

[0063] A phytogenic concrete precast block with water purification function comprises the following mass parts of raw materials:

[0064] 52.5 strength grade fly ash portland cement 90 parts, Blaine specific surface area 500 m 2 / kg;

[0065] volcanic rock 300 parts, porosity 45%, crushing value index 15%, powder content 2%, particle size 10-20 mm;

[0066] silica stone 200 parts, SiO2 content 95% (mass percent), crushing value index 13%, particle size 10-20 mm;

[0067] 400 mesh diatomite 20 parts, SiO2 content 90% (mass percent), water content 2%;

[0068] bamboo fiber 1 part, length 20 mm;

[0069] water 30 parts;

[0070] silica fume 3 parts, Blaine specific surface area 28000 m 2 / kg, SiO2 content 90% (mass percent);

[0071] sodium alginate 2 parts;

[0072] cationic starch 1 part;

[0073] polycarboxylic acid water reducing agent 2 parts.

[0074] A method for preparing a phytogenic concrete precast block with water purification function comprises the following steps:

[0075] Step 1, weighing: weigh the cement, volcanic rock, silica stone, diatomite, bamboo fiber, water, silica fume, sodium alginate, cationic starch, and polycarboxylic acid water reducing agent with the set mixing ratio.

[0076] Step two, mixing: first, the cement, silica, bamboo fiber, silica fume, sodium alginate, cationic starch of step one are added into the mixer in turn and stirred for 3 minutes; then the water and water reducing agent of step one are added into the mixer and continue to stir for 3 minutes to form a uniform slurry with appropriate consistency; finally, the volcanic rock and silica of step one are added into the mixer and continue to stir for 5 minutes to become a uniform mixture, and the mixture is discharged.

[0077] Step three, paving and forming: the mixture of step two is evenly layered and paved in the mold.

[0078] Step four, standard curing: the mixture of step three is placed in the curing room together with the mold for 5 days, the temperature of the curing room is controlled at 20±2℃, and the relative humidity is greater than 95%.

[0079] Step five, demolding: the vegetation concrete is separated from the mold to obtain a vegetation concrete precast block; the precast block is moved to the carbon curing room for stacking, and the distance between adjacent precast blocks is controlled at 100-500mm.

[0080] Step six, carbon curing: the vegetation concrete precast block is cured in the carbon curing room for 28 days, the volume concentration of carbon dioxide in the room is not less than 30%, the relative humidity is 60-70%, and the temperature is 20±2℃.

[0081] Step seven, finished product, quality inspection, and stacking: the vegetation concrete precast block is removed from the carbon curing room, and the finished product is obtained after the quality inspection meets the requirements, and the finished product is stacked.

[0082] Example 4

[0083] A vegetation concrete precast block with water purification function, comprising the following mass fractions of each raw material:

[0084] 52.5 strength grade fly ash portland cement 100 parts, Blaine specific surface area 550m 2 / kg;

[0085] Volcanic rock 400 parts, porosity 45%, crushing value index 10%, powder content 3%, particle size 10-20mm;

[0086] Silica 100 parts, SiO2 content 97% (mass percent), crushing value index 15%, particle size 10-20mm;

[0087] 500 mesh diatomite 30 parts, SiO2 content 88% (mass percent), water content 3%;

[0088] Bamboo fiber 1.5 parts, length 15mm;

[0089] Water 35 parts;

[0090] Silica fume 3.5 parts, Blaine specific surface area 28000 m 2 / kg, SiO2 content 85% (mass percent);

[0091] Sodium alginate 3 parts;

[0092] Cationic starch 1.5 parts;

[0093] Polycarboxylic acid water reducing agent 3 parts.

[0094] A preparation method of a phytogenic concrete precast block with water purification function, comprising the following steps:

[0095] Step one, weighing: weighing the cement, volcanic rock, silica, diatomite, bamboo fiber, water, silica fume, sodium alginate, cationic starch, and polycarboxylic acid water reducing agent according to the set mixing ratio.

[0096] Step two, mixing: first, add the cement, diatomite, bamboo fiber, silica fume, sodium alginate, and cationic starch weighed in step one into a mixer in sequence and stir for 3 min; then add the water and water reducing agent weighed in step one into the mixer and continue to stir for 2 min to form a uniform slurry with appropriate consistency; finally, add the volcanic rock and silica weighed in step one into the mixer and continue to stir for 4 min to become a uniform mixture, and then discharge.

[0097] Step three, paving and forming: evenly layer the mixture of step two in the mold.

[0098] Step four, standard curing: place the mixture and the mold in a curing room for curing for 3 days, with the temperature controlled at 20±2℃ and the relative humidity greater than 95%.

[0099] Step five, demolding: separate the phytogenic concrete from the mold to obtain a phytogenic concrete precast block; then move the precast block to a carbon curing room for stacking, with the distance between adjacent precast blocks controlled at 100-500 mm.

[0100] Step six, carbon curing: cure the phytogenic concrete precast block in the carbon curing room for 28 days, with the carbon dioxide volume concentration not less than 30%, the relative humidity 60-70%, and the temperature 20±2℃.

[0101] Step seven, finished product, quality inspection, and stacking: move the phytogenic concrete precast block out of the carbon curing room, and the finished product is obtained when the quality inspection meets the requirements; then stack the finished product.

[0102] Example 5

[0103] A phytogenic concrete precast block with water purification function, comprising the following mass fractions of raw materials:

[0104] 52.5 strength grade fly ash portland cement 80 parts, Blaine specific surface area 480 m2 / kg;

[0105] Volcanic rock 400 parts, porosity 50%, crushing value index 15%, powder content 2%, particle size 10-20 mm;

[0106] Silica 100 parts, SiO2 content 97% (mass percent), crushing value index 15%, particle size 10-20 mm;

[0107] 400 mesh diatomite 15 parts, SiO2 content 86% (mass percent), water content 2%;

[0108] Bamboo fiber 0.5 parts, length 10 mm;

[0109] Water 25 parts;

[0110] Silica fume 2.5 parts, Blaine specific surface area 28000 m 2 / kg, SiO2 content 85% (mass percent);

[0111] Sodium alginate 1 part;

[0112] Cationic starch 0.5 parts;

[0113] Polycarboxylic acid water reducing agent 1 part.

[0114] A method for preparing a phytogenic concrete precast block with water purification function, comprising the following steps:

[0115] Step one, weighing: weigh the cement, volcanic rock, silica, diatomite, bamboo fiber, water, silica fume, sodium alginate, cationic starch, and polycarboxylic acid water reducing agent according to the set mixing ratio.

[0116] Step two, mixing: first, add the cement, diatomite, bamboo fiber, silica fume, sodium alginate, and cationic starch weighed in step one into a mixer in sequence and stir for 2 min; then add the water and water reducing agent weighed in step one into the mixer and continue stirring for 2 min to form a uniform slurry with appropriate consistency; finally, add the volcanic rock and silica weighed in step one into the mixer and continue stirring for 3 min to become a uniform mixture, and discharge.

[0117] Step three, spreading and forming: spread the mixture of step two evenly in layers in a mold.

[0118] Step four, standard curing: place the mixture of step three together with the mold in a curing chamber for 7 days, with the temperature controlled at 20±2℃ and the relative humidity greater than 95%.

[0119] Step five, demolding: separate the phytogenic concrete from the mold to obtain a phytogenic concrete precast block; move the precast block to a carbon curing chamber for stacking, with the distance between adjacent precast blocks controlled at 100-500 mm.

[0120] Step six, carbon curing: the vegetation concrete precast block is cured in a carbon curing room to an age of 28d, the volume concentration of carbon dioxide in the room is not less than 30%, the relative humidity is 60-70%, and the temperature is 20±2℃.

[0121] Step seven, finished product, quality inspection, and stacking: the vegetation concrete precast block is removed from the carbon curing room, and the finished product is obtained after the quality inspection meets the requirements. The finished product is stacked.

[0122] The following are four comparative examples.

[0123] Comparative Example 1

[0124] Compared with Example 1, diatomite is not added, and the diatomite in Example 1 is replaced with 42.5 strength grade slag portland cement in equal parts.

[0125] Comparative Example 2

[0126] The basalt and silica in Example 1 are replaced with ordinary gravel in equal parts.

[0127] Comparative Example 3

[0128] After demolding, the vegetation concrete precast block in Example 1 is continuously cured under standard conditions to an age of 28d, that is, no carbon curing is performed after demolding.

[0129] The physical and mechanical properties of the above examples and comparative examples are compared. Among them, the same test method and evaluation index are used in the test of the five preferred examples and comparative examples, and the test method and evaluation index are both JC / T 2557-2020 “Vegetation Concrete”.

[0130] 1. Compressive strength test

[0131] According to JC / T 2557-2020 “Vegetation Concrete”, the 7d compressive strength of vegetation concrete should not be less than 3MPa, and the 28d compressive strength should not be less than 10MPa. The compressive strength test is performed on Examples 1-5 and Comparative Examples 1-3, and the results are shown in Table 1. The compressive strength of Comparative Example 1 is less than that of Example 1, because the main component of diatomite is SiO2, which can produce secondary hydration reaction with the hydration of cement to form calcium silicate gel, which improves the strength of concrete after hardening. Compared with Comparative Example 2, the compressive strength of Examples 1-5 is improved to different degrees, which shows that basalt and silica have a strengthening effect on the compressive strength of vegetation concrete. The 28d compressive strength of Comparative Example 3 is less than that of Example 1, which shows that carbon curing after demolding can improve the compressive strength of vegetation concrete.

[0132] Table 1 Compressive strength test results

[0133] 7d compressive strength (MPa) 28d compressive strength (MPa) Example 1 8.0 14.6 Example 2 7.8 14.0 Example 3 7.5 13.5 Example 4 10.3 18.9 Example 5 7.0 12.6 Comparative Example 1 7.3 13.0 Comparative Example 2 6.6 10.3 Comparative Example 3 8.0 12.7

[0134] 2. Porosity test

[0135] According to JC / T 2557-2020 “Vegetation Concrete”, the porosity of vegetation concrete should be between 21% and 30%. The porosity test was performed on Examples 1-5 and Comparative Examples 1-3, and the results are shown in Table 2. The porosity of Example 1 is greater than that of Comparative Example 2, indicating that the addition of volcanic rock and silica can increase the porosity of vegetation concrete.

[0136] Table 2. Porosity test results

[0137] Total porosity (%) Actual porosity (%) Example 1 28.2 26.2 Example 2 27.9 25.7 Example 3 27.5 25.3 Example 4 25.3 23.8 Example 5 30.2 27.9 Comparative Example 1 27.8 25.6 Comparative Example 2 23.3 20.5 Comparative Example 3 28.1 26.0

[0138] 3. pH test

[0139] According to JC / T 2557-2020 “Vegetation Concrete”, the pH of vegetation concrete should be between 6 and 9, which can meet the growth needs of most plants. The pH test was performed on Examples 1-5 and Comparative Examples 1-3, and the results are shown in Table 3. The pH of Comparative Example 2 is greater than that of Example 1, indicating that the addition of volcanic rock and silica can reduce the pH of vegetation concrete. The pH of Comparative Example 3 is greater than that of Example 1, indicating that carbon curing can reduce the pH of vegetation concrete. In the present application, if carbon curing is not performed, the pH of the obtained precast block is as high as 11.5, and even if volcanic rock and silica are used as aggregates, the pH is still higher than 9. Therefore, in the present application, carbon curing is an essential step.

[0140] Table 3. pH test results

[0141] pH Example 1 8.3 Example 2 8.5 Example 3 8.5 Example 4 8.6 Example 5 8.0 Comparative Example 1 8.5 Comparative Example 2 9.9 Comparative Example 3 11.5

[0142] 4. Water purification test

[0143] The water purification test was performed on Examples 1-5 and Comparative Examples 1-3, and the results are shown in Table 4. The water purification effect of Example 1 is better than that of Comparative Example 1, indicating that diatomite can improve the water purification capacity of vegetation concrete. Because diatomite has numerous ordered small pores on its surface, it has stable performance, acid resistance, large pore volume, large pore size, large specific surface area, and strong adsorption. The water purification effect of Examples 1-5 is better than that of Comparative Example 2, indicating that the introduction of volcanic rock and silica in the present application can significantly improve the water purification capacity of vegetation concrete.

[0144] Table 4. Water purification test results

[0145]

[0146]

[0147] From the above tests, the following conclusions can be drawn:

[0148] 1) The incorporation of volcanic rock, silica stone and diatomite can improve the compressive strength of the plant-growing concrete. The incorporation of volcanic rock can increase the actual porosity of the plant-growing concrete; the incorporation of volcanic rock, silica stone and carbon curing can significantly reduce the pH of the plant-growing concrete; the incorporation of volcanic rock, silica stone and diatomite can improve the water purification capacity of the plant-growing concrete.

[0149] 2) The compressive strength, porosity, pH and other indicators of examples 1-5 meet the requirements of the actual engineering application specified in JC / T 2557-2020 “Plant-growing Concrete”.

[0150] The above is only the preferred embodiment of the present application, and it should be understood that the present application is not limited to the form disclosed herein, and should not be considered as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concepts described herein by the above teachings or related art or knowledge. Any modification and change made by those skilled in the art without departing from the spirit and scope of the present application shall be within the protection scope of the appended claims of the present application.

Claims

1. A precast concrete block with water purification function, characterized in that: It comprises the following raw materials by weight: 80-100 parts general-purpose silicate cement, 300-400 parts volcanic rock, 100-200 parts silica, 15-30 parts diatomaceous earth, 0.5-1.5 parts plant fiber, 25-35 parts water, 2.5-3.5 parts silica fume, 1-3 parts sodium alginate, 0.5-1.5 parts cationic starch, and 1-3 parts water-reducing agent; the volcanic rock has a particle size of 10-20 mm; porosity ≥40%, crushing value ≤15%, and powder content ≤3%; The silica particle size is 10~20mm; the SiO2 mass content is ≥95%, and the crushing value is ≤15%; The Blaine specific surface area of ​​the silica fume is 20,000 m². 2 / kg or more, SiO2 mass content ≥85%; During carbon curing, the indoor carbon dioxide volume concentration should be ≥30%, the relative humidity should be 60~70%, and the temperature should be 20±2℃. The preparation of this precast concrete block includes the following steps: S1. Weigh each raw material according to the proportion. First, mix the general silicate cement, diatomaceous earth, plant fiber, silica fume, sodium alginate, and cationic starch. Then add water and water-reducing agent and mix well. Finally, add volcanic rock and silica and mix well to obtain the mixture. The mixtures obtained from S2 and S1 are spread out, shaped in molds, and cured indoors in a conventional manner until demolding. Then, carbon curing is carried out for 28 days to obtain precast concrete blocks with water purification function.

2. The precast concrete block according to claim 1, characterized in that: The general-purpose silicate cement has a Blaine specific surface area of ​​450 m². 2 / kg or above, with a strength grade of 42.5 or above; specifically, it is slag silicate cement or fly ash silicate cement.

3. The precast concrete block according to claim 1, characterized in that: The diatomaceous earth contains ≥85% SiO2 by mass, ≤5% moisture content, and ≥300 mesh.

4. The precast concrete block according to claim 1, characterized in that: The plant fiber has a length of 10-20mm and is a bast fiber of flax or bamboo fiber type.

5. The precast concrete block according to claim 1, characterized in that: The water-reducing agent is a polycarboxylate water-reducing agent.

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