Permeable concrete, also known as porous concrete, is a kind of porous lightweight concrete mixed with aggregate, cement, reinforcing agent, and water.
This kind of paving material can allow rainwater to flow into the ground, effectively supplement groundwater, alleviate some urban environmental problems such as the rapid decline of the city's groundwater level, and can effectively eliminate the hazards of environmental pollution such as oil compounds on the ground, while protecting Groundwater, maintaining ecological balance, can alleviate the urban heat island effect. It is conducive to the healthy development of the human living environment and the work of urban rainwater management and water pollution prevention and control, and has special significance.
The permeable concrete system has a series of color formulas, in line with the creativity of the design, and the paving construction is carried out in accordance with the decorative styles of different environments and individual requirements. This is a special paving material that cannot be achieved by traditional paving and general permeable bricks.
Permeable concrete is composed of aggregate, cement, water, etc., and mostly single-grain or intermittent coarse aggregate is used as the skeleton. The amount of fine aggregate is generally controlled within 20% of the total aggregate; the cement can be silicate. Cement, ordinary Portland cement and Portland slag cement; the admixtures can be silica fume, fly ash, slag fine powder, etc. When feeding, first add cement, admixtures, coarse aggregate, then add half of the amount of water, and stir for 30s; then add additives (additives, pigments, etc.) and stir for 60s; finally add the remaining water and stir for 120s to discharge.
The construction of permeable concrete mainly includes paving, forming, surface treatment, joint treatment and other processes. Paving can be carried out by mechanical or manual methods; the forming can be carried out by using a flat plate vibrator, a vibrating leveling roller, a manual push-pull roller, a vibrating leveling beam, etc.; the surface treatment is mainly to ensure that the surface look and feel is improved. The surface should be repaired or cleaned; the joints of the permeable concrete pavement are basically the same as those of ordinary concrete, and the shrinkage joints are arranged at equal intervals, and the spacing should not exceed 6m.
After the construction of the permeable concrete, it shall be covered and cured, and shall be maintained with water for at least 7 days. During the curing period, the pores of the concrete surface shall be prevented from being contaminated by sediment. The daily maintenance of concrete includes daily cleaning and cleaning of plugged pores. Methods such as blower blow, high pressure flushing or vacuum cleaning can be used to clean and block the pores.
(1) Mixture: Setting time (initial setting is not less than 2h);
(2) Hardened concrete: strength (C15～C30);
Water permeability (not less than 1mm/s);
(3) Freeze-thaw cycle resistance: generally not less than D100.