Anti-freezing ecological concrete suitable for cold regions and preparation method of anti-freezing ecological concrete

Abstract

The invention belongs to the technical field of building materials, and provides anti-freezing ecological concrete suitable for cold regions and a preparation method of the anti-freezing ecological concrete. The concrete disclosed by the invention is prepared from the following components in parts by mass: 180 to 250 parts of cement, 900 to 1300 parts of modified coarse aggregate, 150 to 300 parts of fine aggregate, 90 to 130 parts of water, 8 to 20 parts of a composite additive, 3 to 8 parts of an ecological nutrient and 15 to 35 parts of composite fiber. Through component innovation and synergistic effect mechanism optimization, the comprehensive performance of the concrete is remarkably improved, and the prepared concrete has outstanding practical value and can be widely applied to side slope treatment, desertification control, ecological corridor construction and other projects in cold regions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, and in particular to an anti-freezing ecological concrete suitable for cold regions and a preparation method thereof. BACKGROUND

[0002] Traditional concrete materials take high strength and durability as the core target, but have significant defects in ecological functions. With the increasing demand for ecological restoration and sustainable development, the existing technology exposes the following problems: ecological isolation: conventional concrete structures are dense, with low porosity, which cannot support plant root penetration, resulting in low vegetation coverage in slope protection and river engineering, and increasing the risk of water and soil loss; insufficient freeze-thaw resistance: the pore structure of slope protection materials in cold regions is unreasonable, and water retention causes frost heaving damage, and the existing ecological concrete does not optimize the anti-freezing and water permeability; contradiction between structural stability and ecological function: high porosity is beneficial to water permeability, but insufficient coarse aggregate ratio easily leads to mechanical property decline; and existing porous concrete is difficult to balance particle grading and plant growth space; poor deformation adaptability: traditional materials have too high rigidity and cannot adapt to small deformation caused by foundation settlement or temperature stress, resulting in structure cracking and destroying the continuity of the vegetation layer.

[0003] Current part of ecological concrete attempts to improve planting performance by adding organic matter or opening hole design, but ignores the toxic effect of pore blockage and salt and alkali precipitation on plant roots under freeze-thaw cycles. In addition, a single functional optimization scheme (such as only increasing water permeability or compressive strength) is difficult to meet the comprehensive needs of water and soil conservation, ecological restoration and engineering safety in complex environments.

[0004] Therefore, it is of great significance to research an anti-freezing ecological concrete suitable for cold regions with high water permeability, freeze-thaw durability, plant compatibility and controllable deformation ability and a preparation method thereof. SUMMARY

[0005] The purpose of the present application is to provide an anti-freezing ecological concrete suitable for cold regions and a preparation method thereof, which solves the deficiencies of existing concrete in water and soil loss prevention effect, anti-freezing performance, plant planting adaptability, pore structure rationality and deformation control.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical scheme:

[0007] The present application provides an anti-freezing ecological concrete suitable for cold regions, which comprises the following components by mass fraction:

[0008] Cement 180-250 parts, modified coarse aggregate 900-1300 parts, fine aggregate 150-300 parts, water 90-130 parts, composite admixture 8-20 parts, ecological nutrient 3-8 parts, and composite fiber 15-35 parts.

[0009] Preferably, the cement is ordinary Portland cement.

[0010] The modified coarse aggregate is granite gravel modified by silane coupling agent KH-550, and the particle size of the modified coarse aggregate is 15-35 mm.

[0011] Preferably, the fine aggregate comprises expanded perlite and aeolian sand, the mass ratio of the expanded perlite to the aeolian sand is 1-2:1-2, and the fineness modulus of the expanded perlite is 2.0-2.5.

[0012] The composite admixture comprises nano calcium carbonate, calcium lignosulfonate, polycarboxylate superplasticizer and ethylene glycol, and the mass ratio of the nano calcium carbonate, the calcium lignosulfonate, the polycarboxylate superplasticizer and the ethylene glycol is 0.8-1.2:1.5-2.5:3.5-4.5:3.

[0013] Preferably, the ecological nutrient agent comprises straw ash and bone meal, and the mass ratio of the straw ash to the bone meal is 4-6:2-3.

[0014] The composite fiber comprises basalt fiber and polyester fiber, and the mass ratio of the basalt fiber to the polyester fiber is 1:1.5-2.5, the length of the basalt fiber is 18-22 mm, and the length of the polyester fiber is 8-12 mm.

[0015] Preferably, the preparation method of the modified coarse aggregate comprises the following steps: mixing granite gravel and silane coupling agent KH-550, and then standing.

[0016] The mass ratio of the granite gravel to the silane coupling agent KH-550 is 100:0.2-0.6, and the standing time is 22-26 h.

[0017] The application further provides a preparation method of the anti-freezing ecological concrete suitable for cold regions.

[0018] Preferably, the mixing time is 18-26 min.

[0019] Preferably, the curing is sectional curing, and the sectional curing is as follows:

[0020] The first 7 days are covered with plastic film for moisture retention, and then water is sprayed 1-2 times per day, and the curing time is greater than or equal to 21 days.

[0021] Compared with the prior art, the application has the following beneficial effects:

[0022] The concrete prepared by the application has excellent water loss prevention performance, excellent anti-freezing performance, good plant planting adaptability and suitable deformation amount, so that the plant growth demand can be met while the strength of the concrete is ensured, and the volume change caused by the large day and night temperature difference can be effectively adapted to reduce cracking.

[0023] The application significantly improves the comprehensive performance of the concrete through component innovation and synergistic mechanism optimization, has outstanding practical value, and can be widely applied to slope treatment, desertification prevention and control and ecological corridor construction in cold regions. DETAILED DESCRIPTION

[0024] The application provides an anti-freezing type ecological concrete suitable for cold regions, and the concrete comprises the following components in mass fraction:

[0025] Cement 180-250 parts, modified coarse aggregate 900-1300 parts, fine aggregate 150-300 parts, water 90-130 parts, composite admixture 8-20 parts, ecological nutrient agent 3-8 parts and composite fiber 15-35 parts.

[0026] In the application, the mass fraction of the cement is preferably 190-240 parts, further preferably 200-230 parts, and more preferably 210-220 parts.

[0027] The mass fraction of the modified coarse aggregate is preferably 950-1250 parts, further preferably 1000-1200 parts, and more preferably 1100-1150 parts.

[0028] The mass fraction of the fine aggregate is preferably 170-280 parts, further preferably 200-260 parts, and more preferably 220-240 parts.

[0029] The mass fraction of the water is preferably 100-120 parts, further preferably 105-115 parts, and more preferably 110-112 parts.

[0030] The mass fraction of the composite admixture is preferably 10-18 parts, further preferably 12-16 parts, and more preferably 13-15 parts.

[0031] The mass fraction of the ecological nutrient agent is preferably 4-7 parts, and further preferably 5-6 parts.

[0032] The mass fraction of the composite fiber is preferably 16-32 parts, further preferably 18-30 parts, and more preferably 20-25 parts.

[0033] In the application, the cement is preferably ordinary portland cement.

[0034] The modified coarse aggregate is preferably granite gravel modified by silane coupling agent KH-550, and the particle size of the modified coarse aggregate is preferably 15-35 mm, further preferably 20-30 mm, and more preferably 24-26 mm.

[0035] In the present application, the granite in the modified coarse aggregate is modified by silane coupling agent KH-550, so that the surface activity is improved, the interface bonding force with the cement paste is significantly enhanced, and the overall strength of the concrete can be effectively improved; the large particle size and the reasonable gradation with the fine aggregate form a rich pore structure, which provides space for plant root growth and water storage, and at the same time enhances the impact resistance of the concrete. The interface transition zone structure between the surface of the coarse aggregate modified by the silane coupling agent and the cement paste is more dense, and the stress transmission is more uniform, so that the concrete has high strength while still maintaining the effective pores formed by the coarse aggregate, thereby synergistically improving the structural stability and pore functionality of the concrete.

[0036] In the present application, the fine aggregate includes expanded perlite and aeolian sand, and the mass ratio of the expanded perlite to the aeolian sand is preferably 1-2:1-2, further preferably 1.2-1.8:1.2-1.8, and further preferably 1.5-1.6:1.5-1.6; the fineness modulus of the expanded perlite is preferably 2.0-2.5, further preferably 2.1-2.4, and more preferably 2.2-2.3, and the particle size of the aeolian sand is preferably 0.0074-0.025 mm, further preferably 0.01-0.02 mm, and more preferably 0.015-0.018 mm.

[0037] The composite admixture includes nano calcium carbonate, calcium lignosulfonate, polycarboxylate superplasticizer, and ethylene glycol, and the mass ratio of the nano calcium carbonate, calcium lignosulfonate, polycarboxylate superplasticizer, and ethylene glycol is preferably 0.8-1.2:1.5-2.5:3.5-4.5:3, further preferably 0.9-1.1:1.6-2.3:3.7-4.2:3, and more preferably 1:1.8-2:3.8-4:3.

[0038] In the present application, the fine aggregate has the characteristics of light weight and porosity, can reduce the bulk density of the concrete, and at the same time, the internal pores can absorb and store water, providing sustained water supply for plant growth; filling the gaps between the coarse aggregates, improving the workability of the concrete, and forming a more reasonable pore gradation with the coarse aggregates.

[0039] In the application, the nano calcium carbonate in the composite admixture promotes cement hydration as a crystal nucleus, and cooperates with the polycarboxylate superplasticizer to reduce the water consumption, improve the cement hydration degree, and increase the concrete density; the retarding effect of the calcium lignosulfonate can avoid the internal stress caused by rapid hydration of concrete in low temperature environment, and the anti-freezing effect of the ethylene glycol can make the concrete still normally hydrate in low temperature, and the internal structure is more uniform, and the frost resistance and strength of the concrete are significantly improved.

[0040] In the application, the ecological nutrient agent comprises straw ash and bone meal, and the mass ratio of the straw ash and the bone meal is preferably 4-6:2-3, further preferably 4.5-5.5:2.2-2.8, and more preferably 5-5.2:2.5-2.6.

[0041] The composite fiber comprises basalt fiber and polyester fiber, and the mass ratio of the basalt fiber and the polyester fiber is preferably 1:1.5-2.5, further preferably 1:1.6-2.2, and more preferably 1:1.8-2; the length of the basalt fiber is preferably 18-22 mm, further preferably 19-21 mm, and more preferably 20 mm; and the length of the polyester fiber is preferably 8-12 mm, further preferably 9-11 mm, and more preferably 10 mm.

[0042] In the application, the basalt fiber in the composite fiber has good compatibility with the cement matrix, can bear the main tensile stress, and can inhibit the expansion of macroscopic cracks; the polyester fiber is uniformly dispersed in the cement paste and the interstitial space of the aggregate, and can prevent the generation and development of microscopic cracks. The two fibers are interwoven in space, form a three-dimensional support network with the aggregate, and cooperatively improve the crack resistance, toughness and deformation capacity of the concrete, so that the concrete is not easy to crack under temperature change and external force, and the adhesion between the concrete and the aggregate is enhanced, and the soil erosion caused by aggregate loosening is reduced.

[0043] In the application, the preparation method of the modified coarse aggregate is as follows: the granite gravel is mixed with silane coupling agent KH-550 and then is left standing.

[0044] The mass ratio of the granite gravel and the silane coupling agent KH-550 is preferably 100:0.2-0.6, further preferably 100:0.3-0.5, and more preferably 100:0.35-0.4; and the standing time is preferably 22-26 h, further preferably 23-25 h, and more preferably 24 h.

[0045] In the present application, cement provides strength basis, modified coarse aggregate and fine aggregate form reasonable pore structure, composite admixture guarantees the performance stability of concrete in low temperature environment, ecological nutrient promotes plant growth, and composite fiber improves the deformation capacity and integrity of concrete. After the growth of plants, the root system penetrates into the pores of concrete and is closely combined with concrete, further enhancing the water and soil loss resistance of concrete; and the pore structure of concrete provides growth space for plant roots, forming a "concrete-plant" symbiotic system, achieving the synergy and unity of water and soil loss prevention, ecological restoration and structural stability.

[0046] The present application also provides a preparation method of the anti-freezing ecological concrete suitable for cold regions, comprising the following steps: mixing modified coarse aggregate, fine aggregate, cement, ecological nutrient, water, composite admixture and composite fiber to obtain concrete mixture, and curing the concrete mixture after pouring.

[0047] In the present application, the mixing time is preferably 18-26 min, further preferably 20-25 min, and more preferably 22-24 min.

[0048] In the present application, the mixing is preferably:

[0049] 1) Put the modified coarse aggregate and fine aggregate into a mixer and stir;

[0050] 2) Add cement and ecological nutrient and stir;

[0051] 3) Mix and stir water and composite admixture until completely dissolved, then add to the mixer and stir;

[0052] 4) Add composite fiber and stir to obtain the concrete mixture;

[0053] In the step 1), the stirring time is preferably 3-4 min;

[0054] In the step 2), the stirring time is preferably 4-6 min, and further preferably 5 min;

[0055] In the step 3), the stirring time is preferably 6-9 min, and further preferably 7-8 min;

[0056] In the step 4), the stirring time is preferably 5-7 min, and further preferably 6 min.

[0057] In the present application, the curing is preferably segmented curing, and the segmented curing is preferably:

[0058] The first 7 days are covered with plastic film for moisture retention, and then water is sprayed 1-2 times a day to keep the surface of the concrete wet, and the curing time is preferably ≥21 days, further preferably ≥22 days, and more preferably ≥24 days.

[0059] The technical solutions provided by the present application are described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.

[0060] In the examples and comparative examples of the present application, the parts are mass parts; the polycarboxylic acid water reducing agent is PCA-I type polycarboxylic acid water reducing agent.

[0061] Example 1

[0062] In this example, the concrete is composed of the following components:

[0063] Ordinary Portland cement 190 parts, modified coarse aggregate (granite crushed stone with a particle size of 25 mm and silane coupling agent KH-550 mixed at a mass ratio of 100:0.3, then left to stand for 23 h) 950 parts, fine aggregate (expanding perlite and aeolian sand at a mass ratio of 1:1, the fineness modulus of the expanding perlite is 2.2, and the particle size of the aeolian sand is 0.015 mm) 170 parts, water 100 parts, composite admixture (mass ratio of nano calcium carbonate, calcium lignosulfonate, polycarboxylic acid water reducing agent and ethylene glycol is 0.9:1.6:3.7:3) 10 parts, ecological nutrient agent (mass ratio of straw ash and bone meal is 4.5:2.2) 4 parts, and composite fiber (mass ratio of basalt fiber of 19 mm and polyester fiber of 9 mm is 1:1.6) 16 parts;

[0064] Preparation of the concrete:

[0065] Mix the modified coarse aggregate and the fine aggregate, stir for 3 min, then add the cement and the ecological nutrient agent, stir for 4 min, to obtain a mixture;

[0066] Mix the water and the composite admixture to obtain a composite admixture solution, add the composite admixture solution to the mixture, stir for 6 min, then add the composite fiber and stir for 5 min, to obtain a concrete mixture;

[0067] Pour the concrete mixture and then perform curing, which is film covering and moisturizing for the first 7 days, then water spraying once a day, and the curing is performed for 21 days.

[0068] Example 2

[0069] In this example, the concrete is composed of the following components:

[0070] Ordinary Portland cement 230 parts, modified coarse aggregate (granite gravel with a particle size of 25 mm and silane coupling agent KH-550 mixed at a mass ratio of 100:0.5 and then left to stand for 25 h) 1200 parts, fine aggregate (expanding perlite and aeolian sand at a mass ratio of 1:1, the fineness modulus of the expanding perlite being 2.2 and the particle size of the aeolian sand being 0.015 mm) 260 parts, water 115 parts, composite admixture (nano calcium carbonate, calcium lignosulfonate, polycarboxylate superplasticizer and ethylene glycol at a mass ratio of 1.1:2.3:4.2:3) 16 parts, ecological nutrient agent (straw ash and bone meal at a mass ratio of 5.5:2.8) 6 parts and composite fiber (basalt fiber of 21 mm and polyester fiber of 11 mm at a mass ratio of 1:2.2) 30 parts;

[0071] Preparation of the concrete:

[0072] The modified coarse aggregate and the fine aggregate were mixed and stirred for 4 min, then the cement and the ecological nutrient agent were added and stirred for 6 min to obtain a mixture;

[0073] The water and the composite admixture were mixed to obtain a composite admixture solution, which was added to the mixture and stirred for 8 min, then the composite fiber was added and stirred for 7 min to obtain a concrete mixture;

[0074] The concrete mixture was poured and cured, the curing being film covering and moisturizing for the first 7 days and then watering twice a day for 22 days.

[0075] Example 3

[0076] In this example, the concrete was composed of the following components:

[0077] Ordinary Portland cement 215 parts, modified coarse aggregate (granite gravel with a particle size of 25 mm and silane coupling agent KH-550 mixed at a mass ratio of 100:0.5 and then left to stand for 24 h) 1125 parts, fine aggregate (expanding perlite and aeolian sand at a mass ratio of 1:1, the fineness modulus of the expanding perlite being 2.25 and the particle size of the aeolian sand being 0.015 mm) 230 parts, water 111 parts, composite admixture (nano calcium carbonate, calcium lignosulfonate, polycarboxylate superplasticizer and ethylene glycol at a mass ratio of 1:2:4:3) 14 parts, ecological nutrient agent (straw ash and bone meal at a mass ratio of 5:3) 5.5 parts and composite fiber (basalt fiber of 20 mm and polyester fiber of 10 mm at a mass ratio of 1:2) 22 parts;

[0078] Preparation of the concrete:

[0079] The modified coarse aggregate and the fine aggregate were mixed and stirred for 3 min, then the cement and the ecological nutrient agent were added and stirred for 5 min to obtain a mixture;

[0080] Mix water and composite admixture to obtain a composite admixture solution, add the composite admixture solution into the mixture, stir for 7 min, then add the composite fiber and stir for 6 min to obtain a concrete mixture;

[0081] Pour the concrete mixture and perform curing, which is film covering and moisturizing for the first 7 days, then spraying water once a day, and curing for 24 days.

[0082] Comparative Example 1

[0083] In Example 3, the composite admixture is deleted, and other steps are the same as those in Example 3.

[0084] Comparative Example 2

[0085] In Example 3, the modified coarse aggregate is replaced by “granite gravel with a particle size of 25 mm”, and other steps are the same as those in Example 3.

[0086] Comparative Example 3

[0087] In Example 3, the composite fiber is deleted, and other steps are the same as those in Example 3.

[0088] Comparative Example 4

[0089] In Example 3, the fine aggregate is replaced by “230 parts of aeolian sand with a particle size of 0.015 mm”, and other steps are the same as those in Example 3.

[0090] Comparative Example 5

[0091] In Example 3, the ecological nutrient is replaced by “5.5 parts of straw ash”, and other steps are the same as those in Example 3.

[0092] The concrete obtained in Examples 1-3 and Comparative Examples 1-5 is subjected to the following performance verification, and the performance detection results are shown in Tables 1 and 2.

[0093] Frost resistance: detected according to the national standard GB / T 50082-2009 “Standard for Testing Methods of Long-term Performance and Durability of Ordinary Concrete” to count the number of freeze-thaw cycles;

[0094] 28d compressive strength: the concrete is made into a test block with a specification of 150mmx150mmx150mm, and detected according to the national standard GB / T 50081-2019 “Standard for Testing Methods of Physical and Mechanical Properties of Concrete”;

[0095] 28d flexural strength: the concrete is made into a test block with a specification of 150mmx150mmx550mm, and detected according to the national standard GB / T 50081-2019 “Standard for Testing Methods of Physical and Mechanical Properties of Concrete”;

[0096] Anti-cracking: the concrete is made into a test block with a size of 1000mmx1000mmx100mm, and the flat plate constraint method is used for detection, and the maximum crack width (mm) and the number of cracks at 28d are counted;

[0097] Plant growth performance: ryegrass is sown on the surface of the concrete, and the plant height, root length and coverage rate are measured and counted after 30d.

[0098] Table 1: performance test results of the concrete obtained in examples 1-3 and comparative examples 1-5

[0099]

[0100]

[0101] Table 2: plant growth performance test results of the concrete obtained in examples 1-3 and comparative examples 1-5

[0102]

[0103] As shown in Table 1, the highest number of freeze-thaw cycles, 28d compressive strength / bending strength and anti-cracking performance of the concrete obtained in examples 1-3 are all better than those of the concrete obtained in comparative examples 1-5.

[0104] As shown in Table 2, the growth rate of ryegrass in examples 1-3 is obviously better than that in comparative examples 1-5, i.e. the plant growth performance is excellent.

[0105] Therefore, by the synergistic design of the modified coarse aggregate, composite admixture and composite fiber, the unity of the frost resistance, structural strength and ecological function of the concrete in cold regions is achieved.

[0106] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A frost-resistant ecological concrete suitable for cold regions, characterized in that: The concrete comprises the following components in parts by mass: 180-250 parts of cement, 900-1300 parts of modified coarse aggregate, 150-300 parts of fine aggregate, 90-130 parts of water, 8-20 parts of composite admixture, 3-8 parts of ecological nutrient agent, and 15-35 parts of composite fiber.

2. The frost-resistant ecological concrete suitable for cold regions according to claim 1, characterized in that: The cement is ordinary Portland cement; The modified coarse aggregate is granite crushed stone modified by silane coupling agent KH-550, and the particle size of the modified coarse aggregate is 15 to 35 mm.

3. The frost-resistant ecological concrete suitable for cold regions according to claim 2, characterized in that: The fine aggregate includes expanded perlite and aeolian sand, wherein the mass ratio of the expanded perlite to the aeolian sand is 1-2:1-2; the fineness modulus of the expanded perlite is 2.0-2.5; The composite admixture comprises nano calcium carbonate, calcium lignin sulfonate, polycarboxylic acid water reducer and ethylene glycol, and the mass ratio of the nano calcium carbonate, calcium lignin sulfonate, polycarboxylic acid water reducer and ethylene glycol is 0.8-1.2:1.5-2.5:3.5-4.5:

3.

4. The frost-resistant ecological concrete suitable for cold regions according to claim 2 or 3, characterized in that: The ecological nutrient comprises straw ash and bone meal, and the mass ratio of straw ash to bone meal is 4-6:2-3; The composite fiber comprises basalt fiber and polyester fiber, the mass ratio of the basalt fiber to the polyester fiber is 1:1.5-2.5, the length of the basalt fiber is 18-22 mm, and the length of the polyester fiber is 8-12 mm.

5. The frost-resistant ecological concrete suitable for cold regions according to claim 2, characterized in that: The modified coarse aggregate is prepared by mixing granite crushed stone and silane coupling agent KH-550 and then allowing the mixture to stand; The mass ratio of the granite crushed stone to the silane coupling agent KH-550 is 100:0.2-0.6, and the standing time is 22-26 hours.

6. The method for preparing frost-resistant ecological concrete suitable for cold regions according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: mixing modified coarse aggregate, fine aggregate, cement, ecological nutrient, water, composite admixture and composite fiber to obtain a concrete mixture, and curing the concrete mixture after pouring.

7. The method for preparing frost-resistant ecological concrete suitable for cold regions according to claim 6, characterized in that: The mixing time is 18 to 26 minutes.

8. The method for preparing frost-resistant ecological concrete suitable for cold regions according to claim 7, characterized in that: The maintenance is segmented maintenance, which includes: Cover with plastic film to keep moist for the first 7 days, then water 1 to 2 times a day. The maintenance time is ≥ 21 days.

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