Permeable concrete has the characteristics of small capacity, insignificant capillary phenomenon of water, high permeability, small cement consumption and simple construction, so the advantages of this new building material are constantly known and gradually applied in the road field. It can increase the rainwater that seeps into the surface, and alleviate some urban environmental problems such as the sharp drop of the city's groundwater level. So what is the practice of permeable concrete? What are its advantages? Let's take a look at it together!
1. Advantages of pervious concrete:
1. When centralized precipitation occurs, it can reduce the burden of urban drainage facilities, prevent rivers from flooding and prevent pollution.
2. It can make rainwater quickly penetrate into the ground, reduce groundwater and keep soil moisture.
3. prevent road area from accumulating water, and do not reflect light at night, so as to increase road safety and traffic comfort.
4. Adjust the temperature and humidity of urban space, improve the urban thermal cycle, and alleviate the heat island effect.
5. Large porosity can reduce the road noise when vehicles are running and create a comfortable traffic environment.
6. A large number of gaps can adsorb urban pollutants (such as dust) and reduce dust pollution.
7. easy to maintain, the gap will not be damaged, and the traffic jam is not easy.
8. Patterns can be designed according to needs, so as to fully integrate with the surrounding environment.
Second, the method of pervious concrete
The raw materials used for pervious concrete are high-strength cement, cementing agent, additives, water, crushed stone aggregate, etc., which are uniformly packaged
A.? The establishment of the on-site mixing station and the stacking of raw materials shall be based on the principle of convenient feeding and the most space saving. The mixer covers an area of about 2m2, and the quantity of cement and gravel reserves is at least 3 times of the daily construction quantity, and various additives need to be stored in a warehouse. The mixing station covers an area of about 3? m2。
b.? On-site mixing technology and transportation measurement: a weighbridge is set on site. The mixture ratio shall be strictly in accordance with the design requirements. Each can of metered cement shall be designed according to the whole bag, the stones shall be weighed by trolleys, and various additives shall be accurately measured in barrel containers. In order to measure quickly, obvious markings can be drawn on cars and barrels after the first weighing, but weighing is still required every time. ? Mixing: put the crushed stone, cement and additives in a mixer for about 1 minute, and then add water according to the workability of the mixture until the mixture meets the requirements.
third, the practice of permeable concrete paving
The paving technology of permeable concrete is similar to concrete paving, but it is different from concrete paving.
Proportion of three kinds of raw materials in the construction process:
In order to construct a high-quality and high-standard permeable concrete floor, it is an important key to strictly control the proportion of the above three kinds of raw materials under the condition of fixed raw materials, and the person in charge must strictly control the proportion at the construction site.
mix proportion of permeable concrete (by mass):
water: cementing agent: macadam: cement = 113: 1: 1518: 31
cement is 42.5Mp? Portland cement
IV. Requirements of permeable concrete pavement base
1. Thickness of permeable concrete pavement: The thickness of panels varies according to different applications of pavement. For light load floors such as sidewalks and bicycle lanes, the thickness of the surface layer is generally not less than 8 cm; For parking lots, plazas and other heavy floors, the surface layer thickness is not less than 1 cm. Considering the cost, the surface layer can be divided into two layers, that is, the surface layer is a permeable concrete layer with a thickness of not less than 3 cm, and the lower layer is a plain permeable concrete layer.
2. In order to ensure that the pavement structure layer has sufficient overall strength and water permeability, there should be a permeable base layer and a cushion layer with good water retention under the surface layer.
requirements for base course: on the compacted layer of plain soil, the base course materials should have proper strength and good water permeability, using graded gravel or graded crushed stone. When graded macadam is used, the maximum particle size of macadam should be less than .7 times of the thickness of the base, and not more than 5 mm.
the cushion is generally made of natural crushed stones, with the particle size less than 1mm, commonly known as melon seeds, and it is paved with a certain thickness and needs to be even and flat.
3. Considering the factors of heavy rain season, in order to prevent excessive water accumulation at the grass-roots level from affecting the foundation, a special permeable pipe row is set at the grass-roots level to lead to the drainage system beside the road, so as to eliminate excessive rainwater when it is used.
Precautions:
(1) A special person shall be responsible for material proportioning at the construction site.
(2) strictly control the water-cement ratio, that is, control the amount of water added. Water is added in 2-3 times during stirring, and it is not allowed to be added at one time.
(3) In order to stir the materials evenly, the mechanical stirring time should be appropriately extended, but it should not be too long.
As a new environmental protection and ecological road material, pervious concrete has attracted increasing attention. The surface of modern cities is mostly covered by reinforced concrete buildings and impervious pavement. Compared with natural soil, ordinary concrete pavement lacks the ability of breathing, absorbing heat and infiltrating rainwater, which brings a series of environmental problems. Concrete has always been regarded as the culprit of destroying nature, but as long as continuous pores are formed, it can create a connection point with the natural environment and greatly change the image of the past. Therefore, pervious concrete is a creative material for restoring the constantly damaged earth environment and will contribute to the sustainable development of mankind.