[TCHS admixtures in concrete] At present, pavement slab or asphalt are the main materials used in pavement construction. These materials do not have ecological and environmental protection functions and can not play a positive role in improving and alleviating the urban environment. In recent years, China, such as developed Europe and the United States, including neighboring Japan, has paid attention to them. To solve this problem, the pervious concrete additive road is used as the main material and technology of municipal construction in practice. Because eco-environmental permeable concrete additives can effectively solve the problem of environmental pollution. The main materials of pervious concrete additives are stones, solidifying agents, whose main technical characteristics are abundant void structure (15%-25%). It can effectively make rainwater infiltrate underground rapidly and reduce to groundwater, which can solve the serious shortage of urban groundwater.
Pervious concrete additives with overflow structure inside, permeable concrete additives with overflow and drainage structure inside the cushion, which can temporarily store rainwater through the pavement, and then infiltrate step by step. Its aquifer structure includes leveling layer, gravel layer and permeable geotextile. When the rainfall is small, the permeability coefficient of the soil foundation is very large, and the water can directly infiltrate into the underground without affecting its bearing capacity (without polluting the groundwater source). When the rainfall is large, when the rainwater fills the whole water storage base, the water level is higher than the internal overflow pipe orifice, and the rainwater can be discharged through the overflow pipe. Overflow pipes should be evenly arranged along the longitudinal direction of pervious concrete additives and away from motor lanes. The number and spacing of overflow pipes should be selected according to the designed rainfall, permeability coefficient of surface and cushion. The permeable concrete additive with overflow and drainage structure inside the cushion can store rainwater infiltrated into the base for a long time. A non-permeable geotextile is set between the base and the cushion. The rainwater can not directly infiltrate into the underground, but is discharged out of the road through the internal underground pipeline. This kind of base is suitable for locations where rainfall is large, permeability coefficient of soil foundation is small, bearing capacity of cushion is very low after seepage, and water source may be polluted.
Pervious concrete additives use color cement, color aggregate, and coloring additives. The color of pervious concrete additives can change at will. In addition to the gray characteristics in people's impressions, pervious concrete additives can present brilliant colors. The commonly used coloring methods of decorative pervious concrete additives include the integral coloring of pigments, the surface coloring of color hardeners, and chemical reaction dyeing.
Pervious concrete additives, the traditional road surface has no pervious function, the city can only rely on surface catchment system and drainage pipe network to eliminate surface rainfall. Because of the rapid development of cities in China, the development of urban infrastructure is seriously lagging behind, and many cities'drainage facilities can not effectively meet the requirements of drainage. Especially in rainstorm season, rainwater accumulation and overflow often occur in cities when rainstorm comes. A large number of rainwater makes the surface runoff increase sharply, and the peak value appears soon, and the runoff coefficient will also increase with the expansion of urban area, which is also an important cause of urban waterlogging in many cities in China in summer. Pervious concrete additives can effectively reduce urban surface runoff, reduce the burden of drainage facilities and relieve the pressure of urban waterlogging because of their good water permeability. At the same time, the use of pervious concrete additives can also reduce the construction scale of urban drainage system and reduce the cost of urban construction.