Modified porous ecological concrete and its application in engineering structures

Abstract

The application provides modified porous ecological concrete, which comprises the following components: coarse aggregate 180-220 parts, sulphoaluminate cement 45-55 parts, modified diatomite 5-10 parts, modified porous ceramsite 4-8 parts, modified fiber 5-10 parts, water reducing agent 2-4 parts, retarder 1-3 parts and water 20-40 parts. The modified porous ecological concrete with high strength and low alkalinity is obtained by taking the coarse aggregate and the sulphoaluminate cement as the main body and adding the modified diatomite, the modified porous ceramsite and the modified fiber components, and the modified porous ecological concrete is applied to slope protection engineering, and the mechanical strength of the concrete and the growth effect of planted grass are good.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology, specifically relating to modified porous ecological concrete and its application in engineering structures. Background Technology

[0002] Ecological porous concrete is a new type of environmentally friendly building material with a special structure and performance between ordinary concrete and topsoil. It is a type of concrete product made from cement, coarse aggregate, water, etc., in a specific mix ratio using a specific process. It has continuous porous structure suitable for the growth of green plants, possessing a certain pore structure and strength. It can reduce environmental impact, adapt to biological growth, and plays a positive role in regulating ecological balance, beautifying the environment, and achieving harmony between humans and nature. Ecological concrete is also known as porous planting concrete, greening concrete, and vegetated concrete. Ecological concrete can be used in slope protection technology, mainly by pouring porous ecological concrete onto the slope surface, and then planting plants within the concrete pores. The plant roots penetrate the concrete to reach the slope surface. This achieves both safety protection and ecological planting, thus enhancing slope stability and improving the natural environment of the slope. It is a new type of slope protection material that effectively combines engineering protection and ecological restoration.

[0003] However, existing porous ecological concrete uses cement, which is highly alkaline, resulting in high alkalinity. Furthermore, the concrete's strength is insufficient, which is detrimental to plant growth and thus limits its application range. Summary of the Invention

[0004] The purpose of this invention is to provide a modified porous ecological concrete and its preparation method. By using coarse aggregate and sulfoaluminate cement as the main components, and adding modified diatomaceous earth, modified porous ceramsite, modified fiber components, etc., a modified porous ecological concrete with high strength and low alkalinity is obtained, which has good effect when applied to slope protection projects.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A modified porous ecological concrete, by weight, comprises the following components: 180-220 parts coarse aggregate, 45-55 parts sulfoaluminate cement, 5-10 parts modified diatomaceous earth, 4-8 parts modified porous ceramsite, 5-10 parts modified fiber, 2-4 parts water-reducing agent, 1-3 parts retarder, and 20-40 parts water.

[0007] Preferably, the coarse aggregate has a particle size of 19.0-26.5 mm, a bulk density of 1250-1350 kg / m3, a porosity of 45-51%, a water absorption rate of 5.2-6.5%, and a crushing index of 13-16%.

[0008] Preferably, the modified diatomaceous earth is obtained by modification with oxalic acid and ferric sulfate; the modified porous ceramsite is obtained by modification with anionic polyacrylamide and sodium lignosulfonate; the modified fiber is obtained by modification with nano-silica; the water-reducing agent is a polycarboxylate water-reducing agent; and the retarder is a sodium tripolyphosphate retarder.

[0009] Preferably, the polycarboxylate superplasticizer has a solid content of 20-22%, a density of 1.067-1.073 g / ml, a pH of 6.2-6.5, and a water reduction rate of 25-28%.

[0010] The preparation method of the above-mentioned modified porous ecological concrete includes the following steps:

[0011] S1: By weight, take 10-20 parts of diatomaceous earth and 0.5-1.5 parts of ferric sulfate and add them to 50-80 parts of 30% oxalic acid aqueous solution. Stir and react at 80-100℃ for 1-3 hours, and filter to obtain modified diatomaceous earth.

[0012] S2: Take 5-10 parts of porous ceramsite by weight, add 5-8 parts of anionic polyacrylamide, 3-6 parts of sodium lignosulfonate and 40-60 parts of water, stir and react at 100-120℃ for 1-3 hours, and filter to obtain modified porous ceramsite.

[0013] S3: The straw is cut, shredded, impurities removed, washed, and dried to obtain pretreated fibers; by weight, 10-20 parts of the pretreated fibers are added to 40-60 parts of a 1% sodium hydroxide solution and mixed, and stirred at 60-80℃ for 30-40 minutes; then 5-10 parts of a 1% nano-SiO2 suspension are added, and ultrasonically vibrated at 30-35℃ for 20-40 minutes, and then cut to obtain modified fibers;

[0014] S4: By weight, mix 100-150 parts of coarse aggregate, 5-10 parts of modified diatomaceous earth, 20-40 parts of modified porous ceramsite, 5-10 parts of modified fiber, and 150-250 parts of 0.5% potassium sulfate aqueous solution, and react at 80-100℃ for 2-4 hours; then add 45-55 parts of sulfoaluminate cement, 2-4 parts of water-reducing agent, 1-3 parts of retarder, and 20-40 parts of water to a concrete mixer and mix for 60-150 seconds to obtain modified porous ecological concrete.

[0015] Preferably, step S1 specifically involves: taking 16 parts by weight of diatomaceous earth and 1.2 parts by weight of ferric sulfate and adding them to 70 parts by weight of 30% oxalic acid aqueous solution, stirring at 85°C and 500 r / min for 2.5 h, and then filtering to obtain modified diatomaceous earth.

[0016] Preferably, step S2 specifically involves taking 7 parts by weight of porous ceramsite, adding 6.5 parts by weight of anionic polyacrylamide, 5 parts by weight of sodium lignosulfonate and 55 parts by weight of water, stirring at 110°C and 600 r / min for 2 hours, and filtering to obtain modified porous ceramsite.

[0017] Preferably, step S3 specifically involves: cutting, shredding, removing impurities, washing, and drying the straw to obtain pretreated fibers; adding 15 parts by weight of the pretreated fibers to 55 parts by weight of a 1% sodium hydroxide solution and mixing them, stirring at 70°C and a speed of 600 r / min for 35 min; then adding 7 parts by weight of a 1% nano-SiO2 suspension and ultrasonically vibrating at 32°C and a power of 3000 W for 35 min, and cutting to obtain modified fibers.

[0018] Preferably, step S4 specifically involves: mixing 120 parts by weight of coarse aggregate, 7 parts by weight of modified diatomaceous earth, 35 parts by weight of modified porous ceramsite, 8 parts by weight of modified fiber, and 220 parts by weight of 0.5% potassium sulfate aqueous solution, and reacting at 90°C for 2.5 hours; then adding 50 parts by weight of sulfoaluminate cement, 3 parts by weight of water-reducing agent, 2 parts by weight of retarder, and 35 parts by weight of water into a concrete mixer and mixing at a speed of 800 r / min for 120 seconds to obtain modified porous ecological concrete.

[0019] The application of any of the above-mentioned modified porous ecological concrete in engineering structures.

[0020] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0021] 1. This invention uses oxalic acid and ferric sulfate to modify diatomaceous earth by loading. The aqueous solutions of oxalic acid and ferric sulfate are weakly acidic, which is used to neutralize the alkaline substances produced during cement hydration, thereby achieving the purpose of reducing alkali. Moreover, the loading method reduces the impact of direct addition on the strength of concrete structures.

[0022] 2. This invention uses porous ceramsite as the matrix and modifies it with anionic polyacrylamide and sodium lignosulfonate to form a strong and stable network structure, thereby improving the stability and strength of the slurry. At the same time, the fibers are modified with sodium hydroxide solution and nano-SiO2 suspension to improve the surface roughness of the fibers, increase the hydrophobicity of the fiber surface, strengthen the interfacial bonding force between the fibers and cement, and synergistically promote the bonding force between sulfoaluminate cement and aggregates, improve the internal microstructure of porous concrete, and synergistically enhance the durability and mechanical strength of porous concrete. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The raw materials used in this invention are sourced from the following sources:

[0025] The porous ceramsite is from Pingxiang Aorong New Materials Co., Ltd., item number JDL; the diatomaceous earth is from Shandong Zhengxing New Materials Co., Ltd., item number CG8; the anionic polyacrylamide is from Wuhan Pushida Biotechnology Co., Ltd., item number 3024; the sodium lignosulfonate is from Shanghai Yuanye Biotechnology Co., Ltd., item number S30635; the sulfoaluminate cement is from Wuhan Jiyesheng Chemical Co., Ltd., item number A00305; the polycarboxylate superplasticizer is from Liaoning Kelong Fine Chemical Co., Ltd., item number SP609; and the sodium tripolyphosphate retarder is from Shanghai Yuanye Biotechnology Co., Ltd., item number S30235.

[0026] Example 1

[0027] This embodiment provides modified porous ecological concrete, the preparation method of which includes the following steps:

[0028] S1: Take 10g of diatomaceous earth and 0.5g of ferric sulfate and add them to 50g of 30% oxalic acid aqueous solution. Stir the mixture at 80℃ and 500r / min for 1h, and filter to obtain modified diatomaceous earth.

[0029] S2: Take 5g of porous ceramsite, add 5g of anionic polyacrylamide, 3g of sodium lignosulfonate and 40g of water, stir at 100℃ and 600r / min for 1h, and filter to obtain modified porous ceramsite.

[0030] S3: The straw is cut, shredded, impurities removed, washed, and dried to obtain pretreated fibers with a length of 7-8 mm; 10 g of pretreated fibers are added to 40 g of 1% sodium hydroxide solution and mixed, and stirred at 600 r / min for 30 min at 60℃; then added to 5 g of 1% nano SiO2 suspension and ultrasonically vibrated at 30℃ for 20 min, and cut to obtain modified fibers;

[0031] S4: Coarse aggregate (particle size 19-22mm, bulk density 1250-1270kg / m³) 3100g of modified diatomaceous earth (porosity 45-47%, water absorption 5.2-5.4%, crushing index 13-14%), 5g of modified porous ceramsite, 20g of modified fiber, and 150g of 0.5% potassium sulfate aqueous solution were mixed and reacted at 80℃ for 2 hours. Subsequently, 45g of sulfoaluminate cement, 2g of polycarboxylate superplasticizer (solid content 20%, density 1.067g / ml, pH=6.2, water reduction rate 25%), 1g of sodium tripolyphosphate retarder, and 20g of water were added to a concrete mixer and stirred at 800r / min for 60s to obtain modified porous ecological concrete.

[0032] Example 2

[0033] This embodiment provides modified porous ecological concrete, the preparation method of which includes the following steps:

[0034] S1: Take 20g of diatomaceous earth and 1.5g of ferric sulfate and add them to 80g of 30% oxalic acid aqueous solution. Stir the mixture at 500r / min for 3h at 100℃ and filter to obtain modified diatomaceous earth.

[0035] S2: Take 10g of porous ceramsite, add 8g of anionic polyacrylamide, 6g of sodium lignosulfonate and 60g of water, stir at 120℃ and 600r / min for 3h, and filter to obtain modified porous ceramsite.

[0036] S3: The straw is cut, shredded, impurities removed, washed, and dried to obtain pretreated fibers with a length of 9-10 mm; 20 g of pretreated fibers are added to 60 g of 1% sodium hydroxide solution and mixed, and stirred at 80℃ and 600 r / min for 40 min; then added to 10 g of 1% nano-SiO2 suspension and ultrasonically vibrated at 35℃ for 40 min, and cut to obtain modified fibers;

[0037] S4: Coarse aggregate (particle size 24.5-26.5mm, bulk density 1320-1350kg / m³) 3 150g of modified diatomaceous earth (porosity 50-51%, water absorption 6.4-6.5%, crushing index 15-16%), 10g of modified porous ceramsite, 40g of modified fiber, and 250g of 0.5% potassium sulfate aqueous solution were mixed and reacted at 100℃ for 4 hours. Subsequently, 55g of sulfoaluminate cement, 4g of polycarboxylate superplasticizer (solid content 22%, density 1.073g / ml, pH=6.5, water reduction rate 28%), 3g of sodium tripolyphosphate retarder, and 40g of water were added to a concrete mixer and stirred at 800r / min for 150s to obtain modified porous ecological concrete.

[0038] Example 3

[0039] This embodiment provides modified porous ecological concrete, the preparation method of which includes the following steps:

[0040] S1: Take 16g of diatomaceous earth and 1.2g of ferric sulfate and add them to 70g of 30% oxalic acid aqueous solution. Stir the mixture at 500r / min for 2.5h at 85℃ and filter to obtain modified diatomaceous earth.

[0041] S2: Take 7g of porous ceramsite, add 6.5g of anionic polyacrylamide, 5g of sodium lignosulfonate and 55g of water, stir at 110℃ and 600r / min for 2h, and filter to obtain modified porous ceramsite.

[0042] S3: The straw is cut, shredded, impurities removed, washed, and dried to obtain pretreated fibers with a length of 8-9 mm; 15 g of the pretreated fibers are added to 55 g of 1% sodium hydroxide solution and mixed, and stirred at 70°C and 600 r / min for 35 min; then 7 g of 1% nano-SiO2 suspension is added and ultrasonically vibrated at 32°C and 3000 W for 35 min, and then cut to obtain the modified fibers;

[0043] S4: Coarse aggregate (particle size 22-24mm, bulk density 1290-1320kg / m³) 3 120g of modified diatomaceous earth (porosity 46-49%, water absorption 5.8-6.2%, crushing index 14-15%), 7g of modified diatomaceous earth, 35g of modified porous ceramsite, 8g of modified fiber, and 220g of 0.5% potassium sulfate aqueous solution were mixed and reacted at 90℃ for 2.5h. Subsequently, 50g of sulfoaluminate cement, 3g of polycarboxylate superplasticizer (solid content 21%, density 1.071g / ml, pH=6.4, water reduction rate 26.5%), 2g of sodium tripolyphosphate retarder, and 35g of water were added to a concrete mixer and stirred at 800r / min for 120s to obtain modified porous ecological concrete.

[0044] Comparative Example 1

[0045] The difference between this comparative example and Example 1 is that step S1 is missing, i.e., the diatomaceous earth is not modified; in step S4, unmodified diatomaceous earth is used directly, and the other steps are the same.

[0046] Comparative Example 2

[0047] The difference between this comparative example and Example 1 is that step S2 is missing, i.e., the porous ceramsite is not modified; in step S4, unmodified porous ceramsite is used directly, and the other steps are the same.

[0048] Comparative Example 3

[0049] The difference between this comparative example and Example 1 is that step S3 is missing, i.e., the fiber is not modified; in step S4, unmodified fiber is used directly, and the other steps are the same.

[0050] Comparative Example 4

[0051] The difference between this comparative example and Example 1 is that oxalic acid was not added in step S1, but only ferric sulfate was added for modification; the other steps are the same.

[0052] Comparative Example 5

[0053] The difference between this comparative example and Example 1 is that sodium lignosulfonate was not added in step S2, while the other steps are the same.

[0054] Comparative Example 6

[0055] The difference between this comparative example and Example 1 is that no nano-SiO2 suspension was added in step S3, while the other steps are the same.

[0056] The porous ecological concrete prepared in Example 1 was used in slope protection engineering. First, weeds, fallen leaves, dead branches, loose soil, and loose stones were removed from the slope surface. The porous concrete was then poured into a hopper. It was moved to a mold by a crane for pouring. After the concrete set, a mixture of tall fescue and bermudagrass seeds was sown on the concrete surface at a rate of 30g per square meter. After sowing, planting soil was laid on the surface, and then non-woven fabric was used to cover the planting soil. The tall fescue and bermudagrass were watered and fertilized regularly after planting. Results showed good plant growth, no cracking in the concrete, and good strength.

[0057] Performance testing:

[0058] Compressive strength testing was conducted according to GB / T50081-2019 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete," using a TYE-2000E compression testing machine. Alkalinity: After testing the compressive strength of the ecological concrete, it was crushed and ground. The sample was placed in a glass beaker with water at a 1:1 ratio, the beaker was sealed with plastic wrap, and soaked for 24 hours. The pH value of the soaking solution was then measured using a PHS3E precision pH meter. Porosity: The porosity of the porous ecological concrete was determined according to the Japanese "Construction Guidelines for Permeable Concrete River Embankments."

[0059] Table 1 Performance Test Results

[0060]

[0061] The performance test results above show that Examples 1-3 exhibit significant improvements in compressive strength, alkalinity, and porosity. Example 3, in particular, demonstrates the most outstanding overall performance.

[0062] The comparative example, however, did not employ the necessary technical solutions, resulting in significantly inferior performance compared to the embodiment in the corresponding tests. The above experimental results further demonstrate the importance of the technical solutions defined in this invention for its technical effects.

[0063] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing modified porous ecological concrete, characterized in that, Includes the following steps: S1: By weight, take 10-20 parts of diatomaceous earth and 0.5-1.5 parts of ferric sulfate and add them to 50-80 parts of 30% oxalic acid aqueous solution. Stir and react at 80-100℃ for 1-3 hours, and filter to obtain modified diatomaceous earth. S2: Take 5-10 parts of porous ceramsite by weight, add 5-8 parts of anionic polyacrylamide, 3-6 parts of sodium lignosulfonate and 40-60 parts of water, stir and react at 100-120℃ for 1-3 hours, and filter to obtain modified porous ceramsite. S3: The straw is cut, shredded, impurities removed, washed and dried to obtain pretreated fibers; By weight, 10-20 parts of pretreated fiber are added to 40-60 parts of 1% sodium hydroxide solution and mixed, and stirred at 60-80℃ for 30-40 min; then 5-10 parts of 1% nano SiO2 suspension are added and ultrasonically vibrated at 30-35℃ for 20-40 min, and cut to obtain modified fiber; S4: By weight, mix 100-150 parts of coarse aggregate, 5-10 parts of modified diatomaceous earth, 20-40 parts of modified porous ceramsite, 5-10 parts of modified fiber, and 150-250 parts of 0.5% potassium sulfate aqueous solution, and react at 80-100℃ for 2-4 hours; then add 45-55 parts of sulfoaluminate cement, 2-4 parts of water-reducing agent, 1-3 parts of retarder, and 20-40 parts of water to a concrete mixer and mix for 60-150 seconds to obtain modified porous ecological concrete; The coarse aggregate has a particle size of 19.0-26.5 mm and a bulk density of 1250-1350 kg / m³. 3 Porosity 45-51%, water absorption 5.2-6.5%, crushing index 13-16%; The water-reducing agent is a polycarboxylate water-reducing agent with a solid content of 20-22%, a density of 1.067-1.073 g / ml, a pH of 6.2-6.5, and a water reduction rate of 25-28%.

2. The method for preparing modified porous ecological concrete according to claim 1, characterized in that, Step S1 is as follows: by weight, 16 parts of diatomaceous earth and 1.2 parts of ferric sulfate are added to 70 parts of oxalic acid aqueous solution with a mass fraction of 30%, and the mixture is stirred at 85°C and 500 r / min for 2.5 h. The modified diatomaceous earth is then obtained by filtration.

3. The method for preparing modified porous ecological concrete according to claim 1, characterized in that, Step S2 is as follows: Take 7 parts by weight of porous ceramsite, add 6.5 parts of anionic polyacrylamide, 5 parts of sodium lignosulfonate and 55 parts of water, stir and react at 110℃ and 600r / min for 2h, and filter to obtain modified porous ceramsite.

4. The method for preparing modified porous ecological concrete according to claim 1, characterized in that, Step S3 specifically involves cutting, shredding, removing impurities, washing, and drying the straw to obtain pretreated fibers. By weight, 15 parts of pretreated fiber were added to 55 parts of sodium hydroxide solution with a mass fraction of 1% and mixed. The mixture was stirred at 70°C and 600 r / min for 35 min. Then, 7 parts of nano-SiO2 suspension with a mass fraction of 1% were added and ultrasonically vibrated at 32°C and 3000 W for 35 min. The modified fiber was then cut to obtain the modified fiber.

5. The method for preparing modified porous ecological concrete according to claim 1, characterized in that, Step S4 is as follows: by weight, 120 parts of coarse aggregate, 7 parts of modified diatomaceous earth, 35 parts of modified porous ceramsite, 8 parts of modified fiber, and 220 parts of 0.5% potassium sulfate aqueous solution are mixed and reacted at 90℃ for 2.5 hours; then 50 parts of sulfoaluminate cement, 3 parts of water-reducing agent, 2 parts of retarder, and 35 parts of water are added to a concrete mixer and stirred at a speed of 800 r / min for 120 seconds to obtain modified porous ecological concrete.

6. The application of the modified porous ecological concrete obtained by the preparation method according to any one of claims 1-5 in engineering structures.

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