Modified porous ecological concrete and application thereof in engineering structure

Abstract

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

Description

Technical Field

[0001] The invention belongs to the technical field of concrete, and specifically relates to modified porous ecological concrete and application thereof in engineering structures. Background Art

[0002] Ecological porous concrete is a new type of environmentally friendly building material with a special structure and performance between ordinary concrete and cultivated soil. It is a type of concrete product made of cement, coarse aggregate, water, etc. in a specific mix ratio and a specific process. It has continuous pores and is suitable for the growth of green plants. It has a certain pore structure and strength, can reduce environmental load, adapt to biological growth, and has a positive effect on regulating ecological balance, beautifying the environment and landscape, and achieving coordination between humans and nature. Ecological concrete is also called porous planting concrete, greening concrete, and vegetation concrete. Ecological concrete can be used for slope protection technology, mainly by pouring porous ecological concrete on the slope surface, and then planting plants in the concrete pores. The plant roots pass through the concrete to reach the slope surface. While achieving safety protection, ecological planting can be achieved, which can not only enhance the stability of the slope surface, but also improve the natural environment of the slope surface. It is a new type of slope protection material that can well combine engineering protection and ecological restoration.

[0003] However, the existing porous ecological concrete uses cement, which is highly alkaline, causing a high alkalinity problem. In addition, the strength of the concrete is not good enough, which is not conducive to the subsequent plant growth, thus affecting the application scope of the porous ecological concrete. Summary of the invention

[0004] The purpose of the present invention is to provide a modified porous ecological concrete and a preparation method thereof. By taking coarse aggregate and sulphoaluminate cement as the main body, 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 is applied to slope protection projects with good effects.

[0005] In order to achieve the above object, the present invention provides the following technical solutions: A modified porous ecological concrete comprises the following components, measured by weight: 180-220 parts of coarse aggregate, 45-55 parts of sulphoaluminate cement, 5-10 parts of modified diatomaceous earth, 4-8 parts of modified porous ceramsite, 5-10 parts of modified fiber, 2-4 parts of water reducer, 1-3 parts of retarder and 20-40 parts of water.

[0006] 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%.

[0007] Preferably, the modified diatomaceous earth is modified with oxalic acid and ferric sulfate; the modified porous ceramsite is modified with anionic polyacrylamide and sodium lignin sulfonate; the modified fiber is modified with nano-silicon dioxide; the water reducer is a polycarboxylate water reducer; and the retarder is a sodium tripolyphosphate retarder.

[0008] Preferably, the polycarboxylate water-reducing agent 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%.

[0009] The preparation method of the modified porous ecological concrete comprises the following steps: S1: In parts by weight, 10-20 parts of diatomaceous earth and 0.5-1.5 parts of ferric sulfate are added to 50-80 parts of 30% by weight oxalic acid aqueous solution, stirred at 80-100°C for 1-3h, and filtered to obtain modified diatomaceous earth; S2: Take 5-10 parts of porous ceramsite, add 5-8 parts of anionic polyacrylamide, 3-6 parts of sodium lignin sulfonate and 40-60 parts of water by weight, stir and react at a temperature of 100-120° C. for 1-3 hours, and filter to obtain modified porous ceramsite; S3: The straw is cut, kneaded, impurity-removed, washed and dried to obtain pretreated fibers; 10-20 parts by weight of the pretreated fibers are added to 40-60 parts by weight of a 1% sodium hydroxide solution, and stirred at a temperature of 60-80°C for 30-40 minutes; then 5-10 parts by weight of a 1% nano-SiO2 suspension are added, ultrasonically vibrated at a temperature of 30-35°C for 20-40 minutes, and the modified fibers are obtained by cutting; S4: In parts by weight, 100-150 parts of coarse aggregate, 5-10 parts of modified diatomite, 20-40 parts of modified porous ceramsite, 5-10 parts of modified fiber and 150-250 parts of 0.5% potassium sulfate aqueous solution are mixed, and reacted at a temperature of 80-100°C for 2-4 hours; then 45-55 parts of sulphoaluminate cement, 2-4 parts of water reducer, 1-3 parts of retarder and 20-40 parts of water are added into a concrete mixer and stirred for 60-150 seconds to obtain modified porous ecological concrete.

[0010] Preferably, step S1 is specifically as follows: by weight, 16 parts of diatomaceous earth and 1.2 parts of ferric sulfate are added to 70 parts of 30% by weight aqueous oxalic acid solution, stirred at 85° C. and at a speed of 500 r / min for 2.5 hours, and the modified diatomaceous earth is filtered.

[0011] Preferably, step S2 is specifically as follows: by weight, take 7 parts of porous ceramsite, add 6.5 parts of anionic polyacrylamide, 5 parts of sodium lignin sulfonate and 55 parts of water, stir and react at a temperature of 110° C. and a speed of 600 r / min for 2 hours, and filter to obtain modified porous ceramsite.

[0012] Preferably, step S3 is specifically as follows: cutting, kneading, removing impurities, washing and drying the straw to obtain pretreated fibers; adding 15 parts of pretreated fibers to 55 parts of 1% sodium hydroxide solution by weight, stirring at a rate of 600 r / min for 35 minutes at a temperature of 70°C; then adding 7 parts of 1% nano-SiO2 suspension by weight, ultrasonically oscillating at a power of 3000 W at a temperature of 32°C for 35 minutes, and cutting to obtain modified fibers.

[0013] Preferably, step S4 is specifically as follows: in parts by weight, 120 parts of coarse aggregate, 7 parts of modified diatomite, 35 parts of modified porous ceramsite, 8 parts of modified fiber and 220 parts of a 0.5% potassium sulfate aqueous solution are mixed, and reacted at a temperature of 90°C for 2.5 hours; then 50 parts of sulphoaluminate cement, 3 parts of a water reducer, 2 parts of a retarder and 35 parts of water are added to a concrete mixer and stirred at a rate of 800 r / min for 120 seconds to obtain modified porous ecological concrete.

[0014] Application of any of the above-mentioned modified porous ecological concrete in engineering structures.

[0015] Compared with the prior art, the advantages and beneficial effects of the present invention are: 1. The present invention uses oxalic acid and ferric sulfate to load-modify diatomite, and uses the weak acidity of aqueous solutions such as oxalic acid and ferric sulfate to neutralize the alkaline substances produced during cement hydration, thereby achieving the purpose of reducing alkali, and reducing the impact of direct addition on the strength of concrete structure in the form of loading.

[0016] 2. The present invention uses porous ceramsite as a matrix, and modifies it with anionic polyacrylamide and sodium lignin sulfonate to form a firm and stable network structure, thereby improving the stability and strength of the slurry; at the same time, the fiber is modified with sodium hydroxide solution and nano-SiO2 suspension to improve the roughness of the fiber surface, improve the hydrophobicity of the fiber surface, strengthen the interfacial bonding force between the fiber and cement, synergistically promote the bonding force between sulphoaluminate cement and aggregates, improve the internal microstructure of porous concrete, and synergistically enhance the durability and mechanical strength of porous concrete. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0018] The sources of raw materials used in the present invention are as follows: Porous expanded clay comes from Pingxiang Aorong New Materials Co., Ltd. with item number JDL; diatomaceous earth comes from Shandong Zhengxing New Materials Co., Ltd. with item number CG8; anionic polyacrylamide comes from Wuhan Pushida Biotechnology Co., Ltd. with item number 3024; sodium lignin sulfonate comes from Shanghai Yuanye Biotechnology Co., Ltd. with item number S30635; sulfoaluminate cement comes from Wuhan Jiyesheng Chemical Co., Ltd. with item number A00305; polycarboxylate water reducer comes from Liaoning Cologne Fine Chemical Co., Ltd. with item number SP609; sodium tripolyphosphate retarder comes from Shanghai Yuanye Biotechnology Co., Ltd. with item number S30235.

[0019] Example 1 This embodiment provides a modified porous ecological concrete, and the preparation method thereof comprises the following steps: S1: Take 10g diatomaceous earth and 0.5g ferric sulfate and add them into 50g 30% oxalic acid aqueous solution, stir at 80℃ and 500r / min for 1h, and filter to obtain modified diatomaceous earth; S2: Take 5g of porous ceramsite, add 5g of anionic polyacrylamide, 3g of sodium lignin sulfonate and 40g of water, stir and react at a temperature of 100°C and a speed of 600r / min for 1h, and filter to obtain modified porous ceramsite; S3: The straw is cut, kneaded, impurity-removed, washed and dried to obtain pretreated fibers with a fiber length of 7-8 mm; 10 g of the pretreated fibers are added to 40 g of a 1% sodium hydroxide solution, and stirred at a temperature of 60°C at a rate of 600 r / min for 30 min; then 5 g of a 1% nano-SiO2 suspension is added, ultrasonically shaken at a temperature of 30°C for 20 min, and the modified fibers are obtained by cutting; S4: Coarse aggregate (particle size 19-22mm, bulk density 1250-1270kg / m 3, porosity 45-47%, water absorption 5.2-5.4%, crushing index 13-14%) 100g, modified diatomite 5g, modified porous ceramsite 20g, modified fiber 5g and 0.5% potassium sulfate aqueous solution 150g were mixed and reacted at 80°C for 2h; then 45g sulphoaluminate cement, 2g polycarboxylate water reducer (solid content 20%, density 1.067g / ml, pH=6.2, water reduction rate 25%), 1g sodium tripolyphosphate retarder and 20g water were added into a concrete mixer and stirred at a rate of 800r / min for 60s to obtain modified porous ecological concrete.

[0020] Example 2 This embodiment provides a modified porous ecological concrete, and the preparation method thereof comprises the following steps: S1: Take 20g of diatomaceous earth and 1.5g of ferric sulfate and add them into 80g of 30% oxalic acid aqueous solution, stir at 100℃ and 500r / min for 3h, and filter to obtain modified diatomaceous earth; S2: Take 10g of porous ceramsite, add 8g of anionic polyacrylamide, 6g of sodium lignin sulfonate and 60g of water, stir and react at a temperature of 120°C and a speed of 600r / min for 3h, and filter to obtain modified porous ceramsite; S3: The straw is cut, kneaded, impurity-removed, washed and dried to obtain pretreated fibers with a fiber length of 9-10 mm; 20 g of the pretreated fibers are added to 60 g of a 1% sodium hydroxide solution, and stirred at 80°C at a rate of 600 r / min for 40 min; then 10 g of a 1% nano-SiO2 suspension is added, ultrasonically shaken at 35°C for 40 min, and the modified fibers are obtained by cutting; S4: Coarse aggregate (particle size 24.5-26.5mm, bulk density 1320-1350kg / m 3 , porosity 50-51%, water absorption 6.4-6.5%, crushing index 15-16%) 150g, modified diatomite 10g, modified porous ceramsite 40g, modified fiber 10g and 0.5% potassium sulfate aqueous solution 250g were mixed and reacted at a temperature of 100°C for 4h; then 55g sulphoaluminate cement, 4g polycarboxylate water reducer (solid content 22%, density 1.073g / ml, pH=6.5, water reduction rate 28%), 3g sodium tripolyphosphate retarder and 40g water were added into a concrete mixer and stirred at a rate of 800r / min for 150s to obtain modified porous ecological concrete.

[0021] Example 3 This embodiment provides a modified porous ecological concrete, and the preparation method thereof comprises the following steps: S1: 16 g of diatomaceous earth and 1.2 g of ferric sulfate were added to 70 g of 30% oxalic acid aqueous solution, stirred at 85 °C and 500 r / min for 2.5 h, and the modified diatomaceous earth was obtained by filtration; S2: Take 7g of porous ceramsite, add 6.5g of anionic polyacrylamide, 5g of sodium lignin sulfonate and 55g of water, stir and react at a temperature of 110°C and a speed of 600r / min for 2h, and filter to obtain modified porous ceramsite; S3: The straw is cut, kneaded, impurity-removed, washed and dried to obtain pretreated fibers with a fiber length of 8-9 mm; 15 g of the pretreated fibers are added to 55 g of a 1% sodium hydroxide solution, and stirred at 70°C at a rate of 600 r / min for 35 min; then 7 g of a 1% nano-SiO2 suspension is added, and ultrasonically vibrated at 32°C and 3000 W for 35 min, and the modified fibers are cut; S4: Coarse aggregate (particle size 22-24mm, bulk density 1290-1320kg / m 3 , porosity 46-49%, water absorption rate 5.8-6.2%, crushing index 14-15%) 120g, modified diatomite 7g, modified porous ceramsite 35g, modified fiber 8g and 0.5% potassium sulfate aqueous solution 220g were mixed and reacted at a temperature of 90°C for 2.5h; then 50g sulphoaluminate cement, 3g polycarboxylate water reducer (solid content 21%, density 1.071g / ml, pH=6.4, water reduction rate 26.5%), 2g sodium tripolyphosphate retarder and 35g water were added into a concrete mixer and stirred at a rate of 800r / min for 120s to obtain modified porous ecological concrete.

[0022] Comparative Example 1 The difference between this comparative example and Example 1 is that step S1 is missing, that is, the diatomaceous earth is not modified; in step S4, unmodified diatomaceous earth is directly used, and the other steps are the same.

[0023] Comparative Example 2 The difference between this comparative example and Example 1 is that step S2 is missing, that is, the porous ceramsite is not modified; in step S4, unmodified porous ceramsite is directly used, and the other steps are the same.

[0024] Comparative Example 3 The difference between this comparative example and Example 1 is that step S3 is missing, that is, the fiber is not modified; in step S4, unmodified fiber is directly used, and the other steps are the same.

[0025] Comparative Example 4 The difference between this comparative example and Example 1 is that oxalic acid is not added in step S1, but only ferrous sulfate is added for modification, and the other steps are the same.

[0026] Comparative Example 5 The difference between this comparative example and Example 1 is that sodium lignin sulfonate is not added in step S2, and the other steps are the same.

[0027] Comparative Example 6 The difference between this comparative example and Example 1 is that no nano-SiO2 suspension is added in step S3, and the other steps are the same.

[0028] The porous ecological concrete prepared in Example 1 is used for slope protection engineering. First, weeds, fallen leaves and branches, floating soil and pumice on the slope are removed, and the porous concrete is poured into the loading hopper; it is moved into the mold by a crane for pouring, and after the concrete solidifies, a mixed grass seed of tall fescue and bermudagrass is sown on the concrete surface, and the sowing amount per square meter is 30g; after sowing, the surface is covered with planting soil, and the surface of the planting soil is covered with non-woven fabric. After the tall fescue and bermudagrass are planted, water and fertilize regularly. The results show that the plant planting is good, and the concrete has no cracking and other phenomena, and the strength is good.

[0029] Performance Test: The compressive strength test was carried out in accordance with GB / T50081-2019 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", and the test instrument was a TYE-2000E pressure testing machine. Alkalinity: After the compressive strength of the ecological concrete was tested, it was crushed and ground, and placed in a glass cup at a ratio of 1:1 between the sample and water. The mouth of the glass cup was sealed with a safety film, and after soaking for 24 hours, the pH value of the aqueous solution after soaking was measured with a PHS3E precision pH meter. Porosity: The porosity of porous ecological concrete was determined in accordance with Japan's "Construction Manual for Permeable Concrete River Embankments".

[0030] Table 1 Performance test results

[0031] From the above performance test results, it can be seen that the compressive strength, basicity and porosity of Examples 1 to 3 have obvious effects, especially the comprehensive performance of Example 3 is the most outstanding.

[0032] However, the comparative example does not adopt the necessary technical solution, resulting in its performance being significantly worse than that of the embodiment in the corresponding performance test. The above experimental results further prove the importance of the technical solution defined in the present invention to its technical effect.

[0033] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A modified porous ecological concrete, It is characterized in that The invention comprises the following components in parts by weight: 180-220 parts of coarse aggregate, 45-55 parts of sulphoaluminate cement, 5-10 parts of modified diatomite, 4-8 parts of modified porous ceramsite, 5-10 parts of modified fiber, 2-4 parts of water reducer, 1-3 parts of retarder and 20-40 parts of water.

2. A modified porous ecological concrete according to claim 1, It is characterized in that The particle size of the coarse aggregate is 19.0-26.5 mm, and the bulk density is 1250-1350 kg / m 3 , porosity 45-51%, water absorption 5.2-6.5%, crushing index 13-16%.

3. A modified porous ecological concrete according to claim 1, It is characterized in that The modified diatomaceous earth is modified by oxalic acid and ferric sulfate; the modified porous ceramsite is modified by anionic polyacrylamide and sodium lignin sulfonate; The modified fiber is obtained by modifying nano-silicon dioxide; the water reducer is a polycarboxylic acid water reducer; and the retarder is a sodium tripolyphosphate retarder.

4. The modified porous ecological concrete according to claim 1, It is characterized in that The polycarboxylate water-reducing agent 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%.

5. A method for preparing modified porous ecological concrete, It is characterized in that The steps include: S1: In parts by weight, 10-20 parts of diatomaceous earth and 0.5-1.5 parts of ferric sulfate are added to 50-80 parts of 30% by weight oxalic acid aqueous solution, stirred at 80-100°C for 1-3h, and filtered to obtain modified diatomaceous earth; S2: Take 5-10 parts of porous ceramsite, add 5-8 parts of anionic polyacrylamide, 3-6 parts of sodium lignin sulfonate and 40-60 parts of water by weight, stir and react at a temperature of 100-120° C. for 1-3 hours, and filter to obtain modified porous ceramsite; S3: cutting, kneading, removing impurities, washing and drying the straw to obtain pretreated fibers; By weight, 10-20 parts of pretreated fibers are added to 40-60 parts of 1% sodium hydroxide solution, and stirred at 60-80°C for 30-40 minutes; then, 5-10 parts of 1% nano-SiO2 suspension are added, ultrasonically vibrated at 30-35°C for 20-40 minutes, and the modified fibers are cut to obtain; S4: In parts by weight, 100-150 parts of coarse aggregate, 5-10 parts of modified diatomite, 20-40 parts of modified porous ceramsite, 5-10 parts of modified fiber and 150-250 parts of 0.5% potassium sulfate aqueous solution are mixed, and reacted at a temperature of 80-100°C for 2-4 hours; then 45-55 parts of sulphoaluminate cement, 2-4 parts of water reducer, 1-3 parts of retarder and 20-40 parts of water are added into a concrete mixer and stirred for 60-150 seconds to obtain modified porous ecological concrete.

6. A method for preparing a modified porous ecological concrete according to claim 5, It is characterized in that Step S1 is specifically as follows: by weight, 16 parts of diatomaceous earth and 1.2 parts of ferric sulfate are added to 70 parts of 30% by weight aqueous oxalic acid solution, stirred at 85° C. and at a speed of 500 r / min for 2.5 hours, and the modified diatomaceous earth is obtained by filtering.

7. A method for preparing a modified porous ecological concrete according to claim 5, It is characterized in that Step S2 is specifically as follows: by weight, take 7 parts of porous ceramsite, add 6.5 parts of anionic polyacrylamide, 5 parts of sodium lignin sulfonate and 55 parts of water, stir and react at a temperature of 110° C. and a speed of 600 r / min for 2 hours, and filter to obtain modified porous ceramsite.

8. A method for preparing a modified porous ecological concrete according to claim 5, It is characterized in that Step S3 specifically comprises: cutting, kneading, removing impurities, washing and drying the straw to obtain pretreated fibers; By weight, 15 parts of pretreated fibers were added to 55 parts of 1% sodium hydroxide solution, and stirred at 70°C at a rate of 600 r / min for 35 min; then 7 parts of 1% nano-SiO 2 The suspension was ultrasonically vibrated at 3000 W for 35 min at 32°C and cut to obtain the modified fiber.

9. A method for preparing a modified porous ecological concrete according to claim 5, It is characterized in that Step S4 is specifically as follows: in parts by weight, 120 parts of coarse aggregate, 7 parts of modified diatomite, 35 parts of modified porous ceramsite, 8 parts of modified fiber and 220 parts of a 0.5% potassium sulfate aqueous solution are mixed, and reacted at a temperature of 90°C for 2.5 hours; then 50 parts of sulphoaluminate cement, 3 parts of a water reducer, 2 parts of a retarder and 35 parts of water are added to a concrete mixer and stirred at a rate of 800r / min for 120s to obtain modified porous ecological concrete.

10. Use of the modified porous ecological concrete according to any one of claims 1 to 9 in engineering structures.

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