Energy-saving and environment-friendly strong water-permeable concrete and preparation method thereof

Abstract

The application relates to the technical field of building materials, and particularly discloses an energy-saving and environment-friendly strong water-permeable concrete and a preparation method thereof. The energy-saving and environment-friendly strong water-permeable concrete comprises the following components in parts by mass: water 100 parts; cement 256-260 parts; fly ash 27-29 parts; modified recycled coarse aggregate 1080-1090 parts; additive 4.4-4.8 parts; the modified recycled coarse aggregate is prepared from recycled coarse aggregate by modification of a modifier; the recycled coarse aggregate is formed by waste and old concrete damage; and the modifier is a compound of isobutyl triethoxysilane, cyclohexyl methacrylate, isooctyl acrylate and hydroxyethyl acrylate. The application has the advantages of improving the strength of the water-permeable concrete.

Description

Technical Field

[0001] This invention relates to the field of building materials, and in particular to an energy-saving and environmentally friendly permeable concrete and its preparation method. Background Technology

[0002] Permeable concrete, also known as sand-free concrete, uses coarse aggregate, which gives it a certain porosity after curing. This allows water to pass through the concrete smoothly, resulting in better drainage, anti-slip properties, sound absorption, and noise reduction. It effectively improves the surface ecological cycle and is beneficial to traffic safety.

[0003] However, due to the large number of voids in permeable concrete, its density is relatively low. Since the strength of ordinary concrete is mainly improved by its density, permeable concrete generally suffers from a significant decrease in strength. Since permeable concrete is mainly used for road paving, the decrease in strength leads to a decrease in its load-bearing capacity, thereby limiting vehicle load and affecting the development of transportation. Therefore, there is still room for improvement. Summary of the Invention

[0004] To improve the strength of permeable concrete, this application provides an energy-saving and environmentally friendly type of highly permeable concrete and its preparation method.

[0005] Firstly, this application provides an energy-saving and environmentally friendly permeable concrete, employing the following technical solution:

[0006] An energy-saving and environmentally friendly permeable concrete comprises the following components in parts by weight:

[0007] 100 parts water;

[0008] 256-260 parts cement;

[0009] 27-29 parts fly ash;

[0010] 1080-1090 parts of modified recycled coarse aggregate;

[0011] 4.4-4.8 parts of admixture;

[0012] The modified recycled coarse aggregate is obtained by modifying recycled coarse aggregate with a modifier;

[0013] The recycled coarse aggregate is made from broken waste concrete.

[0014] The modifier is a compound of isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate.

[0015] By adopting the above technical solution, and modifying the recycled coarse aggregate with a modifier composed of isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate, the bonding ability between the recycled coarse aggregate and cement can be improved, making it less likely for the cement and recycled coarse aggregate to separate. This significantly improves the strength of permeable concrete, maintains high permeability, and better enhances the road surface bearing capacity, which is more conducive to the development of transportation.

[0016] Preferably, the mass ratio of isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate is 15-17:3-5:7-9:4-6.

[0017] By adopting the above technical solution and specifically selecting the mass ratio of isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate, the modification effect of recycled coarse aggregate is better, thus improving the strength of permeable concrete.

[0018] Preferably, the particle size of the recycled coarse aggregate is 8-10 mm.

[0019] By adopting the above technical solution and specifically selecting recycled coarse aggregate with a particle size of 8-10mm, the resulting voids have high drainage performance and are less prone to forming local large pores, resulting in uniform distribution of permeable concrete properties, which is beneficial to improving stability and increasing strength.

[0020] Preferably, the modification method of the modified recycled coarse aggregate is as follows:

[0021] Step 1) Mix isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate and hydroxyethyl acrylate evenly to obtain the modifier;

[0022] Step 2) Add the recycled coarse aggregate into the modifier, heat to 130-140℃, keep the temperature constant at 130-140℃, and soak for 3-4 hours for modification.

[0023] By adopting the above technical solution and heating to 130-140℃, the modification effect is more significant. The modified recycled aggregate is less likely to separate from the cement and can be better connected to form a whole, thus making the permeable concrete stronger.

[0024] Preferably, in step 2), the mass ratio of recycled coarse aggregate to modifier is 1:1.5-2.

[0025] By adopting the above technical solution and specifically selecting the mass ratio of recycled coarse aggregate to modifier, the modifier can fully impregnate the recycled coarse aggregate, ensuring a better modification effect, while reducing modifier waste, better controlling costs, and having high economic value.

[0026] Preferably, in step 2), during the soaking modification process, the rotation speed is 20-30 r / min, and the stirring is continuous.

[0027] By adopting the above technical solution and through continuous stirring, the modification effect is more complete, and the permeable concrete has higher strength.

[0028] Preferably, the admixture is a compound of water-reducing agent and early-strength agent, and the mass ratio of water-reducing agent to early-strength agent is 3.2-3.4:1.2-1.4.

[0029] By adopting the above technical solutions and specifically selecting water-reducing agents and early-strength agents, the construction performance of permeable concrete is improved, the seepage phenomenon is reduced, and the early-strength agents enable the concrete to form a stable structure more quickly, so that the concrete can maintain a high permeability after curing.

[0030] Preferably, the water-reducing agent is a polycarboxylate water-reducing agent; and the early-strength agent is calcium formate.

[0031] By adopting the above technical solution and specifically selecting calcium formate as the polycarboxylate superplasticizer and early strength agent, the water reduction and early strength effects are better, and the performance of permeable concrete is better.

[0032] Secondly, this application provides a method for preparing energy-saving and environmentally friendly permeable concrete, which adopts the following technical solution:

[0033] A method for preparing the above-mentioned energy-saving and environmentally friendly permeable concrete includes the following steps:

[0034] Step 01): Mix cement, fly ash, modified recycled coarse aggregate, and admixtures evenly to obtain a premix;

[0035] Step 02): Add water to the premix and mix evenly to obtain concrete mix.

[0036] Step 03) Pour the concrete mix into the mold, cure and demold to obtain energy-saving and environmentally friendly permeable concrete.

[0037] By adopting the above technical solution, the permeable concrete produced has both high permeability and high strength, making it particularly suitable for road applications. It can effectively improve the road's load-bearing capacity, and the resulting pavement is not prone to cracking, thus showing great application potential.

[0038] In summary, this application has the following beneficial effects:

[0039] 1. Because this application modifies recycled coarse aggregate by using a modifier composed of isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate and hydroxyethyl acrylate, the bonding ability between recycled coarse aggregate and cement is improved, making it less likely for cement to separate from recycled coarse aggregate. This significantly improves the strength of permeable concrete, maintains high permeability while better improving the pavement bearing capacity, and is more conducive to the development of transportation.

[0040] 2. In this application, the preferred method is to select the specific mass ratio of isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate to achieve a better modification effect on recycled coarse aggregate and improve the strength of permeable concrete.

[0041] 3. In this application, it is preferred to select recycled coarse aggregate with a particle size of 8-10mm. The resulting voids have high drainage performance and are less likely to form large local pores, which makes the permeable concrete properties more uniform, which is beneficial to improving stability and strength. Detailed Implementation

[0042] The present application will be further described in detail below with reference to the embodiments.

[0043] Example 1

[0044] An energy-saving and environmentally friendly permeable concrete comprises the following components:

[0045] Water, cement, fly ash, modified recycled coarse aggregate, and admixtures.

[0046] The cement was purchased from Runfeng Cement, silicate cement, P.O42.5R.

[0047] The fly ash is commercially available and is classified as Grade I fly ash.

[0048] The admixture is a combination of water-reducing agent and early-strength agent.

[0049] The water-reducing agent is a polycarboxylate water-reducing agent, purchased from Wuhan Huaxuan High-Tech Co., Ltd., model: PC-306.

[0050] The early-strength agent is calcium formate, which was purchased from Henan Mingzhixin Chemical Products Co., Ltd.

[0051] Modified recycled coarse aggregate is obtained by modifying recycled coarse aggregate with a modifier.

[0052] Recycled coarse aggregate is made from waste concrete and has a particle size of 8-10mm.

[0053] The modifier is a compound of isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate.

[0054] Isobutyltriethoxysilane was purchased from Shandong Yuanjin New Materials Co., Ltd.

[0055] Cyclohexyl methacrylate was purchased from Changzhou Aozun Composite New Materials Co., Ltd.

[0056] Isooctyl acrylate was purchased from Shandong Ruigang Chemical Co., Ltd.

[0057] Hydroxyethyl acrylate was purchased from Shandong Youwang Chemical Products Co., Ltd.

[0058] The modification method for modified recycled coarse aggregate is as follows:

[0059] Step 1): Add 1500 kg of isobutyltriethoxysilane, 300 kg of cyclohexyl methacrylate, 700 kg of isooctyl acrylate and 400 kg of hydroxyethyl acrylate into a stirred tank, stir at 60 r / min for 10 min, mix evenly to obtain the modifier.

[0060] Step 2): Add 1933 kg of recycled coarse aggregate to the modifier, heat to 130°C, maintain the temperature at 130°C, rotate at 20 r / min, stir continuously, modify for 3 h, filter out the solid, ventilate at 110°C for 2 h to obtain modified recycled coarse aggregate.

[0061] The preparation method of energy-saving and environmentally friendly permeable concrete includes the following steps:

[0062] Step 01): Add 256 kg of cement, 27 kg of fly ash, 1080 kg of modified recycled coarse aggregate, 3.2 kg of water-reducing agent, and 1.2 kg of early strength agent into a concrete mixer. Mix at 60 r / min for 15 min until homogeneous to obtain a premix.

[0063] Step 02): Add 100 kg of water to the premix, stir at 60 r / min for 5 min until evenly mixed to obtain concrete mix.

[0064] Step 03): Pour the concrete mix into the mold, water-cur for 3 days, demold, water-cur for 7 days, and let it stand for 28 days to obtain energy-saving and environmentally friendly permeable concrete.

[0065] Example 2

[0066] An energy-saving and environmentally friendly permeable concrete comprises the following components:

[0067] Water, cement, fly ash, modified recycled coarse aggregate, and admixtures.

[0068] The cement was purchased from Runfeng Cement, silicate cement, P.O42.5R.

[0069] The fly ash is commercially available and is classified as Grade I fly ash.

[0070] The admixture is a combination of water-reducing agent and early-strength agent.

[0071] The water-reducing agent is a polycarboxylate water-reducing agent, purchased from Wuhan Huaxuan High-Tech Co., Ltd., model: PC-306.

[0072] The early-strength agent is calcium formate, which was purchased from Henan Mingzhixin Chemical Products Co., Ltd.

[0073] Modified recycled coarse aggregate is obtained by modifying recycled coarse aggregate with a modifier.

[0074] Recycled coarse aggregate is made from waste concrete and has a particle size of 8-10mm.

[0075] The modifier is a compound of isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate.

[0076] Isobutyltriethoxysilane was purchased from Shandong Yuanjin New Materials Co., Ltd.

[0077] Cyclohexyl methacrylate was purchased from Changzhou Aozun Composite New Materials Co., Ltd.

[0078] Isooctyl acrylate was purchased from Shandong Ruigang Chemical Co., Ltd.

[0079] Hydroxyethyl acrylate was purchased from Shandong Youwang Chemical Products Co., Ltd.

[0080] The modification method for modified recycled coarse aggregate is as follows:

[0081] Step 1): Add 1600 kg of isobutyltriethoxysilane, 400 kg of cyclohexyl methacrylate, 800 kg of isooctyl acrylate, and 500 kg of hydroxyethyl acrylate to a mixing tank, stir at 60 r / min for 10 min, and mix evenly to obtain the modifier.

[0082] Step 2): Add 1885 kg of recycled coarse aggregate to the modifier, heat to 135°C, maintain the temperature at 135°C, rotate at 25 r / min, stir continuously, modify for 3.5 h, filter out the solid, ventilate at 110°C for 2 h to obtain modified recycled coarse aggregate.

[0083] The preparation method of energy-saving and environmentally friendly permeable concrete includes the following steps:

[0084] Step 01): Add 258 kg of cement, 28 kg of fly ash, 1085 kg of modified recycled coarse aggregate, 3.3 kg of water-reducing agent, and 1.3 kg of early-strength agent to a concrete mixer. Mix at 60 r / min for 15 min until homogeneous to obtain a premix.

[0085] Step 02): Add 100 kg of water to the premix, stir at 60 r / min for 5 min until evenly mixed to obtain concrete mix.

[0086] Step 03): Pour the concrete mix into the mold, water-cur for 3 days, demold, water-cur for 7 days, and let it stand for 28 days to obtain energy-saving and environmentally friendly permeable concrete.

[0087] Example 3

[0088] An energy-saving and environmentally friendly permeable concrete comprises the following components:

[0089] Water, cement, fly ash, modified recycled coarse aggregate, and admixtures.

[0090] The cement was purchased from Runfeng Cement, silicate cement, P.O42.5R.

[0091] The fly ash is commercially available and is classified as Grade I fly ash.

[0092] The admixture is a combination of water-reducing agent and early-strength agent.

[0093] The water-reducing agent is a polycarboxylate water-reducing agent, purchased from Wuhan Huaxuan High-Tech Co., Ltd., model: PC-306.

[0094] The early-strength agent is calcium formate, which was purchased from Henan Mingzhixin Chemical Products Co., Ltd.

[0095] Modified recycled coarse aggregate is obtained by modifying recycled coarse aggregate with a modifier.

[0096] Recycled coarse aggregate is made from waste concrete and has a particle size of 8-10mm.

[0097] The modifier is a compound of isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate.

[0098] Isobutyltriethoxysilane was purchased from Shandong Yuanjin New Materials Co., Ltd.

[0099] Cyclohexyl methacrylate was purchased from Changzhou Aozun Composite New Materials Co., Ltd.

[0100] Isooctyl acrylate was purchased from Shandong Ruigang Chemical Co., Ltd.

[0101] Hydroxyethyl acrylate was purchased from Shandong Youwang Chemical Products Co., Ltd.

[0102] The modification method for modified recycled coarse aggregate is as follows:

[0103] Step 1): Add 1700 kg of isobutyltriethoxysilane, 500 kg of cyclohexyl methacrylate, 900 kg of isooctyl acrylate and 600 kg of hydroxyethyl acrylate into a stirred tank, stir at 60 r / min for 10 min, mix evenly to obtain the modifier.

[0104] Step 2): Add 1850 kg of recycled coarse aggregate to the modifier, heat to 140°C, maintain the temperature at 140°C, rotate at 30 r / min, stir continuously, modify for 4 hours, filter out the solid, ventilate at 110°C for 2 hours to obtain modified recycled coarse aggregate.

[0105] The preparation method of energy-saving and environmentally friendly permeable concrete includes the following steps:

[0106] Step 01): Add 260kg of cement, 29kg of fly ash, 1090kg of modified recycled coarse aggregate, 3.4kg of water-reducing agent, and 1.4kg of early-strength agent to a concrete mixer. Mix at 60r / min for 15min until homogeneous to obtain a premix.

[0107] Step 02): Add 100 kg of water to the premix, stir at 60 r / min for 5 min until evenly mixed to obtain concrete mix.

[0108] Step 03): Pour the concrete mix into the mold, water-cur for 3 days, demold, water-cur for 7 days, and let it stand for 28 days to obtain energy-saving and environmentally friendly permeable concrete.

[0109] Comparative Example 1

[0110] An energy-saving and environmentally friendly permeable concrete, compared with Example 2, differs only in that:

[0111] In the modifier, isobutyltriethoxysilane is replaced in equal amounts with methyltrimethoxysilane.

[0112] Methyltrimethoxysilane was purchased from Shandong Yuanjin New Materials Co., Ltd.

[0113] Comparative Example 2

[0114] An energy-saving and environmentally friendly permeable concrete, compared with Example 2, differs only in that:

[0115] In the modifier, stearate acrylate is used to replace cyclohexyl methacrylate in an equal amount.

[0116] Acrylic stearate was purchased from Shandong Jinyufeng New Materials Co., Ltd.

[0117] Comparative Example 3

[0118] An energy-saving and environmentally friendly permeable concrete, compared with Example 2, differs only in that:

[0119] In the modifier, dipropylene glycol diacrylate is used to replace isooctyl acrylate in an equal amount.

[0120] Dipropylene glycol diacrylate was purchased from Hubei Biaoyue Biotechnology Development Co., Ltd.

[0121] Comparative Example 4

[0122] An energy-saving and environmentally friendly permeable concrete, compared with Example 2, differs only in that:

[0123] In the modifier, trimethylolpropane trimethacrylate is used to replace hydroxyethyl acrylate in an equal amount.

[0124] Trimethylolpropane trimethacrylate was purchased from Hubei Dongcao Chemical Technology Co., Ltd.

[0125] Comparative Example 5

[0126] An energy-saving and environmentally friendly permeable concrete, compared with Example 2, differs only in that:

[0127] In the modifier, methyltrimethoxysilane is used to replace isobutyltriethoxysilane in equal amounts, stearate acrylate is used to replace cyclohexyl methacrylate in equal amounts, dipropylene glycol diacrylate is used to replace isooctyl acrylate in equal amounts, and trimethylolpropane trimethacrylate is used to replace hydroxyethyl acrylate in equal amounts.

[0128] Methyltrimethoxysilane was purchased from Shandong Yuanjin New Materials Co., Ltd.

[0129] Acrylic stearate was purchased from Shandong Jinyufeng New Materials Co., Ltd.

[0130] Dipropylene glycol diacrylate was purchased from Hubei Biaoyue Biotechnology Development Co., Ltd.

[0131] Trimethylolpropane trimethacrylate was purchased from Hubei Dongcao Chemical Technology Co., Ltd.

[0132] Comparative Example 6

[0133] An energy-saving and environmentally friendly permeable concrete comprises the following components:

[0134] Water, cement, fly ash, coarse aggregate, and admixtures.

[0135] The cement was purchased from Runfeng Cement, silicate cement, P.O42.5R.

[0136] The fly ash is commercially available and is classified as Grade I fly ash.

[0137] The admixture is a combination of water-reducing agent and early-strength agent.

[0138] The water-reducing agent is a polycarboxylate water-reducing agent, purchased from Wuhan Huaxuan High-Tech Co., Ltd., model: PC-306.

[0139] The early-strength agent is calcium formate, which was purchased from Henan Mingzhixin Chemical Products Co., Ltd.

[0140] The coarse aggregate is basalt crushed stone, sourced from commercially available sources, with a particle size of 8-10mm.

[0141] The preparation method of energy-saving and environmentally friendly permeable concrete includes the following steps:

[0142] Step 01): Add 258 kg of cement, 28 kg of fly ash, 1085 kg of coarse aggregate, 3.3 kg of water-reducing agent, and 1.3 kg of early-strength agent to a concrete mixer. Mix at 60 r / min for 15 min until homogeneous to obtain a premix.

[0143] Step 02): Add 100 kg of water to the premix, stir at 60 r / min for 5 min until evenly mixed to obtain concrete mix.

[0144] Step 03): Pour the concrete mix into the mold, water-cur for 3 days, demold, water-cur for 7 days, and let it stand for 28 days to obtain energy-saving and environmentally friendly permeable concrete.

[0145] Experiment 1

[0146] According to GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", the 7-day compressive strength, 28-day compressive strength, and 28-day splitting tensile strength of the concrete samples made from the concrete in each example and comparative example were tested.

[0147] Experiment 2

[0148] According to GB / T25993-2010 "Permeable Pavement Bricks and Permeable Pavement Panels", the permeability level of concrete samples prepared from concrete mixes of each embodiment and comparative example was tested.

[0149] Grade A: Permeability coefficient ≥ 2.0 × 10 -2 .

[0150] Grade B: Permeability coefficient ≥ 1.0 × 10 -2 .

[0151] The specific test data for Experiments 1 and 2 are detailed in Table 1.

[0152] Table 1

[0153]

[0154] According to the data comparison between the embodiments and comparative examples in Table 1, the permeability of each embodiment and comparative example is better. Moreover, the strength of each embodiment is significantly higher than that of each comparative example, especially higher than that of comparative example 6. Comparative example 6 is concrete using natural stone, while the concrete of each embodiment, after being modified by a modifier composed of recycled coarse aggregate, isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate, has a higher strength than that of comparative example 6 which uses natural stone. It can be seen that the modifier composed of isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate can significantly improve the bonding force between recycled coarse aggregate and cement stone, thus significantly improving the strength of concrete after curing.

[0155] In Comparative Examples 1-5, the compound system of isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate was disrupted, resulting in concrete strength of the modified recycled coarse aggregate that could only barely approach that of Comparative Example 6 using natural aggregate. This shows that the modification effect brought about by the compound of butyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate is excellent, and replacing any one of them will lead to a significant decrease in the modification effect.

[0156] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An energy-saving and environmentally friendly permeable concrete, characterized in that: The components include the following parts by mass: 100 parts water; 256-260 parts cement; 27-29 parts fly ash; 1080-1090 parts of modified recycled coarse aggregate; 4.4-4.8 parts of admixture; The modified recycled coarse aggregate is obtained by modifying recycled coarse aggregate with a modifier; The recycled coarse aggregate is made from broken waste concrete. The modifier is a compound of isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate. The mass ratio of isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate, and hydroxyethyl acrylate is 15-17:3-5:7-9:4-6. The modification method of the modified recycled coarse aggregate is as follows: Step 1), mix isobutyltriethoxysilane, cyclohexyl methacrylate, isooctyl acrylate and hydroxyethyl acrylate evenly to obtain the modifier; Step 2) Add the recycled coarse aggregate into the modifier, heat to 130-140℃, keep the temperature constant at 130-140℃, and soak for 3-4 hours for modification.

2. The energy-saving and environmentally friendly permeable concrete according to claim 1, characterized in that: The particle size of the recycled coarse aggregate is 8-10 mm.

3. The energy-saving and environmentally friendly permeable concrete according to claim 1, characterized in that: In step 2), the mass ratio of recycled coarse aggregate to modifier is 1:1.5-2.

4. The energy-saving and environmentally friendly permeable concrete according to claim 3, characterized in that: In step 2), during the soaking and modification process, the rotation speed is 20-30 r / min, and the stirring is continuous.

5. The energy-saving and environmentally friendly permeable concrete according to claim 1, characterized in that: The admixture is a compound of water-reducing agent and early-strength agent, and the mass ratio of water-reducing agent to early-strength agent is 3.2-3.4:1.2-1.

4.

6. The energy-saving and environmentally friendly permeable concrete according to claim 5, characterized in that: The water-reducing agent is a polycarboxylate water-reducing agent; the early strength agent is calcium formate.

7. A method for preparing energy-saving and environmentally friendly permeable concrete according to any one of claims 1-6, characterized in that: Includes the following steps: Step 01): Mix cement, fly ash, modified recycled coarse aggregate, and admixtures evenly to obtain a premix; Step 02), add water to the premix and mix evenly to obtain concrete mix; Step 03) Pour the concrete mix into the mold, cure, and demold to obtain energy-saving and environmentally friendly permeable concrete.

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