The Ecological and Environmental Advantages of Permeable Brick -- The Preferred Permeable Material for Sponge City

As we all know, China is a country with concurrent droughts and floods, and the contradiction between water retention in arid areas and drainage in rainy areas is extremely prominent. Northern cities, especially inland cities, are seriously threatened by the lack of water resources all the year round, with an annual water shortage of 3 billion cubic meters; southern cities often cause road surface water due to heavy rains, which seriously hinders urban traffic and residents' travel. However, with the rapid development of our country's economy, many towns are covered by reinforced concrete houses, large infrastructure, various impervious sites and roads. While these impervious sites and roads have heat storage, they lack respiration and rain and snow permeability, which aggravates the deterioration of the climate and brings the so-called "heat island effect", which makes the natural water resources very little moisten the vegetation and return to the earth, and also increases the burden of the dredging system and aggravates the pollution of rivers.

In April 2012, the concept of "sponge city" was first proposed in the "2012 Low-Carbon City and Regional Development Technology Forum"; on December 12, 2013, General Secretary Xi Jinping emphasized in the speech of the "Central Urbanization Work Conference": "When upgrading the urban drainage system, priority should be given to leaving the limited rainwater behind, giving priority to more use of natural forces for drainage, and building a sponge city with natural storage, natural infiltration, and natural purification".

Therefore, the extensive use of permeable materials to pave various sites and pavements is the trend of road development in China and the world, and it is also one of the necessary measures for human beings to protect water resources and maintain ecological balance.

Ecological and environmental advantages of permeable pavement

The internal structure of permeable pavement and pavement (referred to as permeable pavement) is composed of a series of porous structures connected with the outside air to form a skeleton, and at the same time, it can meet the requirements of road and pavement strength and durability.

Permeable pavement includesWater permeable brick pavementPermeable concrete pavement andPermeable asphalt pavementand so on;Among thempermeable brickpavement than the other twoHave a unique reusability.China's traditional cobblestone pavement for garden paving is also a kind of permeable pavement. Some permeable floor tiles are combined with greening to form a semi-green ground. Permeable pavement because of its good environmental benefits more and more people's attention.

Maintain the balance of urban soil ecological environment
Permeable pavement has both good water permeability and moisture retention, which not only takes into account the use requirements of human activities for hardened ground, but also approaches the ecological advantages of natural lawn and soil floor through its own performance, so as to reduce the damage degree of urban non-permeable hardened ground to nature, and effectively protect the living space of animals, plants and microorganisms below the permeable pavement floor, therefore, it reflects the concept of sustainable development of "symbiosis with the environment.

Good flood control and drainage performance
Due to its good water permeability, it can effectively alleviate the flood discharge pressure of the urban drainage system, the runoff curve is gentle, its peak is low, and the flow is also slowly rising and falling, which is undoubtedly beneficial to the urban flood control. Therefore, paving permeable ground is a positive measure for waterlogging prevention in urban squares.

The role of improving the light environment
Due to the existence of pores, the light projected onto the surface of the permeable pavement surface produces diffuse reflection, thus avoiding the glare caused by directional reflection that often occurs in smooth floor tiles or stones. The water surface gathered on the impermeable ground in rainy days will also produce glare. This glare is particularly serious under the lights at night, which is one of the important reasons for many traffic accidents in rainy days at night. Due to the timely elimination of surface water, the permeable pavement overcomes the defects caused by the "drift", "splash", "night glare" and other impervious ground, which is also beneficial to urban traffic safety.

With sound absorption
When sound waves hit the surface of permeable pavement, the sound waves cause air movement in small holes or gaps inside the permeable pavement. The air movement speed close to the surface of the hole wall is slow. Due to friction and viscous resistance of air movement, part of the sound energy is converted into heat energy, thus attenuating the sound waves. At the same time, the heat loss caused by the heat exchange between the air and the hole wall in the small hole can also attenuate the sound energy. Due to the increasing number of urban high-rise buildings and elevated roads, coupled with the aircraft noise passing through the urban area, these high noise sources are projected from the city over the surface of permeable pavement. According to the above principle, permeable pavement relies on its unique sound absorption and noise reduction mechanism to improve the urban sound environment. Ordinary non-permeable hardened square ground can only re-reflect sound waves, not sound absorption and noise reduction. On the other hand, the porous structure of the permeable pavement can reduce the tire noise of the vehicle running on it, and it is also advantageous to reduce the traffic noise.permeable brickThe pore structure can effectively reduce the road noise by 6-10 dB.

Environmental protection and optimization of urban environment
Permeable engineering materials with large porosity can adsorb urban pollutants (such as dust), reduce dust pollution, and filter surface sewage. Moreover, it can effectively prevent the occurrence of surface runoff in rainy days, so that garbage can be prevented from floating everywhere with surface runoff and dirty water everywhere. Make the city clean and more environmentally friendly whether it is sunny or rainy.

Beautify the environment
A variety of colorings can be incorporated into the binder so thatPervious brick pavementThe color becomes diverse, and it is easy to form various patterns. It can be designed freely in combination with the surrounding landscape, getting rid of the single, dignified and depressed black pavement before, enriching the color of the urban pavement and beautifying the landscape effect of the city. This example in our country has a lot, our country is actively studying, now has permeable ecological color art floor, it is not only ecological environmental protection, and color, texture, fancy and changeable, suitable for different landscape style needs. Gulou Street, located in Zhongwei City, Ningxia, was applied.Water permeable brick pavementA bottle of mineral water poured down, but it completely seeps down in two seconds, solving the problem of slippery road surface in rainy and snowy weather in the past.

significant economic benefits
According to expert estimates, Nanjing can be transformed into a permeable pavement area of about 3.7 million square meters. If all the transformation is completed, it can store 690000 cubic meters of water, which is equivalent to the displacement of 70 pumps. If this part of precipitation is mixed into the sewage system, it will be seriously wasted. In 2007, Beijing renovated nine Olympic municipal roads such as Yuquan West Street and the eastern section of Stadium North Road, laying 5500 meters of trails, covering 25000 square meters of trails and saving 12000 cubic meters of water annually; permeable material pavement of the ground and impermeable material pavement of the ground engineering cost is basically the same or lower.

Effective river pollution control
Urban river pollution control is of great significance in urban construction.Pervious brick pavementIt can be used for river slope protection to prevent water and soil erosion due to the erosion of river embankment by water flow, which is conducive to the growth of green plants. The application effect exceeds the assumption of the relevant departments to implement the ecological restoration project on the river bank. Hangzhou city in order to implement the "canal heritage" plan, large-scalePervious brick pavementApplied to the embankment and slope protection project of urban river, it can realize "clear water, green bank and beautiful scenery", and become a good place for citizens to relax and play.

have good water storage
      Pervious brick pavementIt can make rainwater penetrate into the ground quickly, replenish groundwater, maintain soil moisture, maintain the ecological balance of groundwater and soil, improve urban ecological conditions, and avoid engineering geological disasters such as ground subsidence and housing foundation subsidence caused by excessive exploitation of groundwater. It is estimated that 50 million square meters of permeable floor can store 30 million cubic meters of water according to the annual rainfall of 600 millimeters, which is equivalent to the capacity of a medium-sized reservoir. Visiblepermeable brickThe water storage potential of the paved road is huge!

The role of permeable pavement in the protection of urban groundwater resources
The traditional non-permeable pavement unilaterally emphasizes the waterproof and anti-seepage performance of the hardened ground. The pavement completely blocks the natural rainfall from the soil layer and groundwater at the lower part of the pavement. Rainfall has to be discharged into the surface water sources such as rivers, lakes and seas through the urban drainage system pipe network, which makes it difficult for the urban underground water source to be replenished in time and seriously affects the effective use of rainwater. At the same time, when rainfall occurs on impervious ground, rainwater is first discharged into the sewer through the drainage slope of the ground or the surface ditch. Before entering the sewer, rainwater can enter the urban underground drainage system through a long distance of surface runoff. This process makes relatively clean rainwater dissolve into a large number of urban surface pollutants, and the secondary pollution generated in this runoff process enters the surrounding surface natural water bodies through the urban drainage system, thus increasing the pollution of these natural water bodies. The permeable pavement penetrates the rainwater directly into the lower soil through the seepage path communicating with the underground cushion layer, and the rainwater can be purified through the filtration of the soil layer.

Therefore, the use of permeable pavement instead of impermeable pavement can effectively alleviate the negative impact of urban impermeable hardened ground on urban water resources. Japan is a rainy country. The country's average annual rainfall per unit area is 1,800mm, which is 215 times the world's average annual rainfall. In the 1970 s, in order to solve the problem of "foundation subsidence caused by groundwater extraction", Japan adopted the "underground reduction countermeasure of rainwater" and developed and applied permeable asphalt pavement. In the early 1980 s, Japan's Ministry of Construction implemented the "Rainwater Infiltration Plan". Japan's permeable pavement is mainly used in parks, squares, parking lots, sports grounds and urban roads. At the beginning of 1996, Tokyo alone laid permeable ground and paved 495,000m2 of floor. According to statistics, the rainwater outflow rate of Tokyo's permeable pavement was reduced from 51.8 to 5.4. Since the 1990 s, the international popular use of such as permeable asphalt pavement,Water permeable brick pavementAs well as similar to China's garden cobblestone paving and other permeable pavement covering the city hardened ground, this move to improve the urban urban rainwater utilization, to ensure the effective supplement of urban groundwater is of great significance.

Effect of Permeable Pavement on Improvement of Thermal and Humid Environment in City Square and Urban Area
Due to a series of porous structures connected with the external air and the lower permeable cushion, the rich capillary water in the soil under the permeable pavement absorbs a large amount of sensible heat and latent heat through the natural evaporation and transpiration under the action of solar radiation, thus reducing the surface temperature, thus effectively alleviating the "heat island phenomenon". Therefore, the water permeable pavement in the city square and the urban area will affect the temperature of the city square and the urban area as well as the evaporation of the urban water body and the transpiration of the greening system, which has a significant effect on improving the thermal environment of the urban area and forming the local wind. "Urban desiccation" is one of the chain reactions of urban heat island effect. The common wind and sand dusting phenomenon in northern cities in the rainy season is due to the reduction of surface humidity and evaporation, the humidity of the air and the surface is too small, and the air is increasingly dry. This phenomenon is particularly evident in the water shortage of northern cities, these cities if the use of permeable pavement, permeable pavement evaporation of water vapor will increase the humidity of the air, which is also beneficial to alleviate the "urban drying", the role of humidification can effectively reduce the urban ground dust and "sandstorm" hazards.

Effect of Permeable Pavement on Improvement of Urban Surface Soil Ecological Environment
The impervious pavement has seriously damaged the living environment of animals and plants on the surface soil of urban areas, and changed the original ecological balance of nature. The urban underlayer, including city squares, buildings, roads and other facilities, has replaced the original forests, green spaces and fields of nature, forming an "urban desert". Wild animals and plants have gradually lost their living environment and are constantly decreasing to the point of extinction. It can be said that the impervious and hardened ground of the city is one of the root causes of a series of urban surface ecological environment crises. The United Nations Environment Programme (United Nations Environment Pro2 gram, referred to as UNEP) to develop the "Human Environment Declaration" and "Convention on Biological Diversity" is in response to the above crisis and put forward the world-wide ecological protection regulations. Permeable pavement has both good water permeability and moisture retention, which not only takes into account the use requirements of human activities for hardened ground, but also approaches the ecological advantages of natural lawn and soil floor through its own performance, so as to reduce the damage degree of urban non-permeable hardened ground to nature, and effectively protect the living space of animals, plants and microorganisms below the permeable pavement floor, therefore, it reflects the concept of sustainable development of "symbiosis with the environment.

Effect of permeable pavement on urban waterlogging prevention
The development of urban infrastructure in China is seriously lagging behind, which makes the urban drainage facilities can not effectively meet the requirements of drainage and flood control during rainstorm, and the phenomenon of rainwater accumulation and flooding often occurs on the hardened ground in urban areas. In this case, non-permeable pavement will undoubtedly increase the pressure on the urban drainage system, which is an important factor for urban waterlogging in many cities in China in summer. The impervious ground can only rely on the surface catchment system and urban drainage pipe network to eliminate the surface rainfall. In the rainstorm, the surface runoff increases sharply, and the peak value appears soon, and the flow rises and falls sharply. The permeable pavement due to its good water permeability performance of the seepage capacity, can effectively alleviate the urban drainage system of the flood pressure, runoff curve smooth, its peak is low, and the flow is also slowly rise and fall, which is undoubtedly beneficial for urban flood control. Therefore, paving permeable ground is a positive measure for waterlogging prevention in urban squares.