High-performance pervious concrete and preparation method thereof

Abstract

The invention discloses high-performance pervious concrete and a preparation method thereof, and belongs to the technical field of civil engineering materials. Based on 100 parts of P.O42.5 cement, the cement comprises the following components in parts by weight: 520-640 parts of gravel, 60-70 parts of sand, 4-5 parts of siliceous active enhancer and 30-40 parts of water. Preferably, the particle size of the gravel is 10-20 mm, and the particle size of the sand is 0 The preparation method comprises the following steps: dry-mixing the cement, the sand and the gravel, adding the water and the reinforcing agent, stirring, inserting and tamping layer by layer, compacting and curing. The obtained concrete has high permeability coefficient and high compressive strength, is low in cement consumption, and is suitable for sidewalks of sponge cities, residential roads and parking lots.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of civil engineering materials, and particularly relates to a high-performance pervious concrete and a preparation method thereof. BACKGROUND

[0002] With the advancement of social economy and urbanization, areas that were once covered with vegetation are now replaced by infrastructure, parking lots, streets, and sidewalks, resulting in water in these places only flowing radially and not directly penetrating into the soil. The loss of these natural surfaces greatly disrupts the water cycle, and the overuse of impervious coverings presents cities with the challenges of increased runoff, difficulty in groundwater recharge, flooding, and water quality degradation. Urban runoff is composed of oil, organic and non-organic materials, and solids on the surface of roads, streets, and urban areas, which need to be properly managed, collected, and treated so that they can be reused for green spaces, agriculture, and industry. Another challenge that cannot be ignored is that covering the ground with impermeable pavements greatly reduces the probability of energy exchange between the underlying cushion and the upper layer, and is one of the main factors that increase the urban heat island effect (UHI). Therefore, in construction projects, it is crucial to design and build high-permeability pavements, which are beneficial for alleviating water shortages, urban flooding, and urban heat island effects.

[0003] Pervious concrete is a highly permeable material that contains a large number of interconnected voids that allow rainwater and other water sources to pass through. The pavement formed by pervious concrete allows rainwater to penetrate into the underlying base layer instead of producing runoff. Due to its high permeability, not only is urban flooding alleviated, but groundwater supply can also be replenished. Moreover, pervious concrete pavements can balance temperature differences by releasing vapor and heat energy from the surface, reducing the impact of urban "heat islands", and thus contributing to the sustainability of urban areas.

[0004] In recent years, permeable concrete and related research have attracted widespread attention. Permeable concrete typically consists of coarse aggregate, water, cement, and little or no fine aggregates, with a porosity ranging from 10% to 25%, compressive strength from 10 MPa to 30 MPa, and a permeability coefficient of 0.5 to 15 cm / s. Compared to traditional concrete, workability and compressive strength are not the most important performance indicators. Permeable concrete aims to ensure optimal compressive strength while maintaining necessary permeability. Pore structure is a key factor determining the compressive strength and permeability of concrete. Numerous scholars have explored factors affecting porosity, including aggregate size and type, cementitious materials, water-cement ratio, binder ratio, admixtures, and compaction methods. Studies have shown a correlation between strength and porosity. Cementitious material properties are affected by the water-cement ratio, additives, and mixing time. Permeable concrete can also be made with different types of cement, such as ordinary Portland cement, Portland pozzolanic cement, and fly ash-based polymers. It is important to note that the effect of the water-cement ratio on the performance of permeable concrete differs from that of traditional concrete. Increasing the water-cement ratio in permeable concrete makes it too fluid, causing sedimentation and loss of permeability. Decreasing the water-cement ratio reduces the bonding strength of the slurry, leading to weaker concrete strength. Therefore, the water-to-cement ratio is only effective within a specific and optimal range. To achieve the required permeability, porosity, and compressive strength, the optimal mix design for permeable concrete must be implemented. Currently, to ensure strength, permeable concrete uses up to 300 kg / m³ of cement, significantly increasing its cost. These challenges threaten the large-scale application and promotion of high-performance permeable concrete. The design and preparation methods for high-performance permeable concrete urgently need improvement to overcome the current dilemma of not being able to simultaneously achieve high compressive strength and high permeability. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a high-performance permeable concrete and its preparation method. This concrete is inexpensive, while also possessing high compressive strength and high permeability, requiring less than 300 kg of cement per cubic meter, exhibiting high compressive strength and ideal permeability.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] One of the objectives of this invention is to provide a high-performance permeable concrete, based on 100 parts of P.O42.5 grade cement, with raw materials including: 520-640 parts crushed stone (coarse aggregate), 60-70 parts sand (fine aggregate), 4-5 parts reinforcing agent and 30-40 parts water;

[0008] The reinforcing agent is a reinforcing agent containing silicon-based active ingredients.

[0009] Further, the particle size of the crushed stone is 5-30 mm. Preferably, the particle size of the crushed stone is 10-20 mm.

[0010] Further, the particle size of the sand is 0-4.75mm. Preferably, the particle size of the sand is 0-2.34mm.

[0011] Further, the reinforcing agent is a pervious concrete reinforcing agent produced by Green Carbon Technology Co., Ltd. Other manufacturers' special pervious concrete reinforcing agents can also be used.

[0012] The second object of the present application is to provide a preparation method of high-performance pervious concrete, comprising the following steps: sequentially adding cement, sand and gravel into a mixer, stirring for 1-2 minutes to make them fully mixed and uniform; then sequentially adding water and a reinforcing agent, stirring for 2-3 minutes until all the materials are uniformly dispersed to obtain a mixture; inserting and tamping the mixture in 3-4 layers, troweling and curing as required to obtain high-performance pervious concrete.

[0013] The third object of the present application is to provide an application of high-performance pervious concrete in sidewalks, residential roads or parking lots in the construction of sponge cities.

[0014] Compared with the prior art, the present application has the following advantages and technical effects:

[0015] The pervious concrete of the present application significantly reduces the cement consumption while maintaining high water permeability and high compressive strength; and the particle size of the aggregate can be selected from a wide range, which is convenient for local material selection and greatly reduces the preparation cost. In actual application scenarios, the concrete can effectively prevent road water accumulation and prevent the risk of skidding of pedestrians and vehicles; at the same time, it can store rainwater in the internal structure of the road to adjust the road temperature through water evaporation, significantly alleviating the problem of high road temperature. In addition, rainwater can penetrate into underground soil through the concrete to effectively supplement groundwater, which has a positive effect on maintaining the balance of urban ecological systems. In summary, the high-performance pervious concrete of the present application has practicality and environmental value, and is an ideal environmentally friendly material suitable for green infrastructure construction. DETAILED DESCRIPTION

[0016] The various exemplary embodiments of the present application will now be described in detail, which should not be considered as limiting the present application, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present application.

[0017] It should be understood that the terms described in the present application are only for describing the specific embodiments, and are not intended to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value within the stated range and any other stated value or intermediate value within the stated range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0018] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art to which this application pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All documents mentioned herein are incorporated by reference to disclose and describe in full the methods and / or materials which are described therein. In case of conflict between the content of the specification and that of any document incorporated herein by reference, the content of the specification prevails.

[0019] Many modifications and variations of this application of the application can be made without departing from its spirit or scope, which will be apparent to those skilled in the art. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only.

[0020] As used herein, the terms "comprise", "comprising", "include", "including", "have" and "having" and the like are open-ended, that is, they mean "including but not limited to".

[0021] In order to solve the problems of high cost and the need to balance high strength and high permeability, the embodiment of the application provides a preparation method of high-performance pervious concrete, which comprises the following steps: cement, sand and gravel are sequentially added into a stirrer, and stirring is performed for 1-2 minutes, so that the cement, sand and gravel are completely mixed and uniformly distributed; then water and a reinforcing agent are sequentially added, and stirring is performed for 2-3 minutes, until all the materials are uniformly dispersed, to obtain a mixture; the mixture is inserted and tamped to be compacted in 3-4 layers, is leveled, and is maintained according to requirements, to obtain the high-performance pervious concrete.

[0022] By using the method, the high-performance pervious concrete can be prepared, the water permeability coefficient of the concrete can reach 3.8-11 mm / s, and the compressive strength can reach 27-53 MPa.

[0023] In the method, based on 100 parts of P.O42.5 grade cement, the raw materials further comprise: 520-640 parts of gravel (coarse aggregate), 60-70 parts of sand (fine aggregate), 4-5 parts of a reinforcing agent and 30-40 parts of water; wherein the reinforcing agent is a reinforcing agent containing a siliceous active ingredient.

[0024] The high-performance pervious concrete provided by the application is suitable for areas where drainage is difficult. In the selection of cement, P.O42.5 grade cement is preferentially used, and other types of cement of the same grade can also be used instead, including but not limited to Portland cement, slag Portland cement, pozzolanic Portland cement, fly ash Portland cement and the like.

[0025] The dosage of the reinforcing agent is preferably 4-5 parts based on 100 parts of cement. Specifically, if the dosage of the reinforcing agent exceeds 8 parts, the material cost will increase significantly, which is difficult to meet the economic demand of basic road engineering; if the dosage is less than 3 parts, the bonding strength of the concrete will be insufficient, and the processing performance of the concrete will be reduced, which will affect the construction quality.

[0026] The aggregate used in the application comprises fine aggregate and coarse aggregate, and the dosages and particle sizes of the two need to be strictly controlled.

[0027] The dosage of the coarse aggregate needs to be controlled in the range of 520-640 parts (based on 100 parts of cement). If the dosage exceeds 640 parts, the thickness of the cement paste wrapped on the surface of the aggregate will be too thin, which will directly lead to insufficient bonding strength of the concrete; if the dosage is less than 520 parts, the relative dosage of the cementing material will be increased, which not only greatly increases the cost, but also reduces the water permeability of the concrete. In terms of particle size selection, the suitable particle size range of the coarse aggregate is 5-30 mm, and the optimal particle size interval is 10-20 mm.

[0028] The dosage of the fine aggregate needs to be controlled in the range of 60-70 parts (based on 100 parts of cement). If the dosage exceeds 70 parts, the surface of the pervious concrete is prone to have floating sand phenomenon, which will reduce the wear resistance; if the dosage is less than 60 parts, the dosage of the cement needs to be increased to ensure the basic performance, which not only increases the cost, but also reduces the strength of the concrete. In terms of particle size selection, the suitable particle size range of the fine aggregate is 0-4.75 mm, and the optimal particle size interval is 0-2.34 mm.

[0029] In the concrete formula of the application, the dosage of water needs to be strictly controlled in a specific range (based on 100 parts of P.O42.5 grade cement, the corresponding dosage of water is 30-40 parts): if the water dosage exceeds 40 parts, the internal pores of the concrete will be filled with excess paste, which will significantly reduce the water permeability; if the water dosage is less than 30 parts, the cementing material and the aggregate will be difficult to fully integrate, which will lead to insufficient flowability of the concrete mixture and reduced processability, and finally increase the difficulty of construction operation.

[0030] The cement used in the application is not particularly limited, and the ordinary cement commonly used in the construction field can meet the basic performance requirements, and other types of cement of the same grade (such as Portland cement, slag Portland cement, etc.) can also be compatible, which has certain flexibility in material selection.

[0031] In addition, the concrete of the application can additionally add various functional additives based on the above-mentioned core components (cement, aggregate, reinforcing agent, water) according to the actual engineering requirements, such as colorants for color customization, tailings for improving resource utilization, etc., so as to expand the application scenarios and additional value of the concrete.

[0032] In the following preferred embodiments of the present application, the raw materials include: 520-640 parts (such as 520 parts, 550 parts, 560 parts, 10 parts or 640 parts) of crushed stone, 60-70 parts (such as 60 parts or 70 parts) of sand, 4-5 parts of reinforcing agent (such as 4 parts or 5 parts) and 30-40 parts (such as 30 parts, 35 parts or 40 parts) of water, based on 100 parts of P.O42.5 grade cement.

[0033] The water permeable concrete of the present application has excellent performance and low material cost, and is suitable for sidewalks, residential roads, parking lots, tree grilles on sidewalks, foundations / floors of greenhouses, water-based recreation centers, road edge drainage pipes and seawalls, and the like, and is particularly suitable for sponge city construction.

[0034] The "parts" in the present application, unless otherwise specified, refer to mass parts.

[0035] The raw materials used in the present application are all commercially available.

[0036] The technical solutions of the present application are further described below through examples.

[0037] The amounts of the raw materials used in the following examples of the present application refer to the amounts of each raw material per cubic meter.

[0038] Example 1

[0039] A high-performance water permeable concrete, the raw materials of which are as follows: P.O42.5 grade cement 100 kg, crushed stone (particle size 5-10 mm) 640 kg, sand (particle size 0-2.34 mm) 70 kg, reinforcing agent (purchased from the Green Carbon Intelligence Company, same below) 4 kg, and water 40 kg.

[0040] A method for preparing a high-performance water permeable concrete: the cement, sand and crushed stone are sequentially added to a mixer, stirred for 1 minute to make them completely mixed and uniform; then the water and the reinforcing agent are sequentially added, stirred for 2 minutes until all the materials are uniformly dispersed, to obtain a mixture; the mixture is inserted and tamped to be compacted in 3-4 layers, smoothed and cured as required (the curing conditions are: standard curing, temperature 20±2℃, humidity ≥95%, same below), to obtain the high-performance water permeable concrete.

[0041] Example 2

[0042] A high-performance water permeable concrete, the raw materials of which are as follows: P.O42.5 grade cement 100 kg, crushed stone (particle size 5-10 mm) 610 kg, sand (particle size 0-2.34 mm) 70 kg, reinforcing agent 4 kg, and water 35 kg.

[0043] A preparation method of high-performance pervious concrete: cement, sand and gravel are sequentially added into a stirring machine, and stirred for 1 minute to make them completely mixed and uniform; then water and a reinforcing agent are sequentially added, and stirred for 2 minutes until all the materials are uniformly dispersed to obtain a mixture; the mixture is inserted and tamped to be compacted in 3-4 layers, is leveled and is maintained according to requirements to obtain the high-performance pervious concrete.

[0044] Example 3

[0045] A high-performance pervious concrete, raw materials are as follows: P.O42.5 grade cement 100 kg, gravel (particle size 5-10 mm) 560 kg, sand (particle size 0-2.34 mm) 65 kg, reinforcing agent 4 kg, water 35 kg.

[0046] A preparation method of high-performance pervious concrete: cement, sand and gravel are sequentially added into a stirring machine, and stirred for 1 minute to make them completely mixed and uniform; then water and a reinforcing agent are sequentially added, and stirred for 2 minutes until all the materials are uniformly dispersed to obtain a mixture; the mixture is inserted and tamped to be compacted in 3-4 layers, is leveled and is maintained according to requirements to obtain the high-performance pervious concrete.

[0047] Example 4

[0048] A high-performance pervious concrete, raw materials are as follows: P.O42.5 grade cement 100 kg, gravel (particle size 5-10 mm) 550 kg, sand (particle size 0-2.34 mm) 60 kg, reinforcing agent 4 kg, water 35 kg.

[0049] A preparation method of high-performance pervious concrete: cement, sand and gravel are sequentially added into a stirring machine, and stirred for 1 minute to make them completely mixed and uniform; then water and a reinforcing agent are sequentially added, and stirred for 2 minutes until all the materials are uniformly dispersed to obtain a mixture; the mixture is inserted and tamped to be compacted in 3-4 layers, is leveled and is maintained according to requirements to obtain the high-performance pervious concrete.

[0050] Example 5

[0051] A high-performance pervious concrete, raw materials are as follows: P.O42.5 grade cement 100 kg, gravel (particle size 5-10 mm) 520 kg, sand (particle size 0-2.34 mm) 70 kg, reinforcing agent 5 kg, water 30 kg.

[0052] A preparation method of high-performance pervious concrete: cement, sand and gravel are sequentially added into a stirring machine, and stirred for 1 minute to make them completely mixed and uniform; then water and a reinforcing agent are sequentially added, and stirred for 2 minutes until all the materials are uniformly dispersed to obtain a mixture; the mixture is inserted and tamped to be compacted in 3-4 layers, is leveled and is maintained according to requirements to obtain the high-performance pervious concrete.

[0053] Comparative Example 1

[0054] A concrete was prepared with the following ingredients: 100 kg of P.O 42.5 grade cement, 330 kg of crushed stone (particle size 5-10 mm), 140 kg of sand (particle size 0-2.34 mm), 3 kg of reinforcing agent, and 30 kg of water.

[0055] The preparation method was the same as that of Example 1.

[0056] Comparative Example 2

[0057] A concrete was prepared with the following ingredients: 100 kg of P.O 42.5 grade cement, 350 kg of crushed stone (particle size 5-10 mm), 150 kg of sand (particle size 0-2.34 mm), 3 kg of reinforcing agent, and 30 kg of water.

[0058] The preparation method was the same as that of Example 1.

[0059] Comparative Example 3

[0060] A concrete was prepared with the following ingredients: 100 kg of P.O 42.5 grade cement, 370 kg of crushed stone (particle size 5-10 mm), 160 kg of sand (particle size 0-2.34 mm), 3 kg of reinforcing agent, and 30 kg of water.

[0061] The preparation method was the same as that of Example 1.

[0062] Performance test:

[0063] After the concrete prepared in Examples 1-5 and Comparative Examples 1-3 was standard cured for 28 days, the compressive strength test was performed in accordance with GB / T 50081-2019 “Standard for Testing Methods of Physical and Mechanical Properties of Concrete”, and the permeability coefficient test was performed in accordance with GJJ / T 135-2009 “Technical Specification for Permeable Cement Concrete Pavement”. The results are shown in Table 1.

[0064] Table 1: Performance test results of different concretes

[0065] Compressive strength (MPa) Permeability coefficient (mm / s) Example 1 27.63 10.93 Example 2 31.19 9.41 Example 3 36.98 7.43 Example 4 40.11 5.37 Example 5 52.95 3.88 Comparative Example 1 15.23 8.22 Comparative Example 2 19.37 7.42 Comparative Example 3 20.83 4.74

[0066] Generally, the higher the compressive strength of permeable concrete, the lower the permeability coefficient. Currently, existing permeable concrete has the problem of low compressive strength (generally lower than 25 MPa). A permeable concrete with excellent performance not only has a high permeability coefficient, but also has a high compressive strength. The permeable concrete of the present application has a compressive strength of 27-53 MPa and a permeability coefficient of 3.8-11 mm / s.

[0067] As can be seen from Table 1, the water-permeable concrete prepared in the embodiments of the present application has the advantage that, compared with other water-permeable concrete, when the water-permeable coefficient of the water-permeable concrete is equivalent, the water-permeable concrete of the present application has higher compressive strength. For example, the water-permeable coefficient and the compressive strength of the water-permeable concrete of Example 1 are 32.97% and 81.42% higher than those of Comparative Example 1, respectively; the water-permeable coefficient and the compressive strength of the water-permeable concrete of Example 2 are 14.48% and 105.79% higher than those of Comparative Example 1, respectively; the compressive strength of the water-permeable concrete of Example 3 is 90.91% higher than that of Comparative Example 2; the compressive strength of the water-permeable concrete of Example 4 and Example 5 is 92.56% and 154.20% higher than that of Comparative Example 3, respectively.

[0068] The above merely provides the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of the changes or replacements within the technical scope disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A high-performance permeable concrete, characterized in that, Based on 100 parts of P.O42.5 grade cement, the raw materials also include: 520-640 parts crushed stone, 60-70 parts sand, 4-5 parts reinforcing agent and 30-40 parts water; The reinforcing agent is a reinforcing agent containing silicon-based active ingredients.

2. The high-performance permeable concrete according to claim 1, characterized in that, The particle size of the crushed stone is 5-30mm.

3. The high-performance permeable concrete according to claim 1, characterized in that, The particle size of the crushed stone is 10-20 mm.

4. The high-performance permeable concrete according to claim 1, characterized in that, The particle size of the sand is 0-4.75 mm.

5. The high-performance permeable concrete according to claim 1, characterized in that, The particle size of the sand is 0-2.34 mm.

6. A method for preparing high-performance permeable concrete as described in any one of claims 1-5, characterized in that, Includes the following steps: Cement, sand, and gravel are added to a mixer in sequence and mixed for 1-2 minutes; then water and reinforcing agent are added in sequence and mixed for 2-3 minutes to obtain a mixture; the mixture is compacted in 3-4 layers, smoothed, and cured to obtain high-performance permeable concrete.

7. The application of high-performance permeable concrete as described in any one of claims 1-5 in sidewalks, residential roads or parking lots in sponge city construction.