I. Composition and Performance of Permeable Concrete
1、? Composition of permeable concrete?
Permeable concrete is a new type of green building material, which is mainly composed of special cementing agent for permeable concrete, crushed stone and water.
( 1)? Cementing agent The special cementing agent for permeable concrete is a powdery material based on high-strength portland cement, and various additives are added to increase strength and cohesive force. Inorganic weather-resistant pigments can be added according to user's requirements.
(2)? Gravel used in gravel permeable concrete should be high-quality stone, and its physical performance indexes are shown in table 1. Gravel particles also have certain requirements. According to their granularity range, they are divided into three semicolons: 1 #, 2 # and 3 #. See Table 2 for the specific particle range.
Table 1? Physical performance index table of crushed stone/%acicular particle content/%silt content/%apparent density /(kg? M-3) Close packing density /(kg? M-3) Void ratio/%
(3) Water can be ordinary tap water. Unfiltered turbid groundwater or used unclean water cannot be used.
2、? Performance of Colored Permeable Concrete See Table 3 for the physical and mechanical performance indexes of pervious concrete.
Second, the permeable concrete pavement construction technology
1、? Models? Construction personnel shall carry out parting and regional formwork erection according to the design requirements, and pay attention to the height, verticality and flooding slope of formwork erection.
2, mixing according to the size of the engineering quantity, configuration of mechanical mixers with different capacities, mechanical mixer within a certain range of the ground, should be set to prevent water and materials scattered receiving equipment (such as square bucket), in order to protect the health of the construction environment, reduce the cleaning work after construction.
Permeable concrete cannot be mixed manually, and ordinary concrete mixer should be used. When mixing, the materials should be put into the mixer according to the specified proportion and feeding order. Cement and macadam are stirred for about 30 seconds, then they are initially stirred, and then the specified amount of water is added for 2 ~ 3 times to continue stirring for about 1.5 ~ 2 min. Depending on the mixing uniformity, the mechanical stirring time can be appropriately extended, but it is not advisable to stir for too long.
Attention should be paid to when mixing:
(1) There should be a special person in charge of material proportioning at the construction site. Design and apply the mix proportion according to the different locations, environments, bearing requirements, patterns and colors of the project.
(2) Strictly control the water cement ratio, that is, control the water addition. When stirring, add water for 2 ~ 3 times, and do not add water at one time.
(3) In order to stir the materials evenly, the mechanical stirring time can be appropriately extended, but it should not be too long.
3、? The transportation of permeable concrete is dry concrete material, and its initial setting is fast. The transportation time of the mixture is generally controlled according to the climatic conditions, and is basically controlled within 10min. Don't stop during transportation, the cart must be stable.
4、? Paving and pouring permeable concrete is a hard concrete material, which has fast initial setting and must be paved in time. For roads in scenic spots, large-scale construction is divided into blocks and warehouses, and the loose paving coefficient is1.1~1.15. Spread the mixture evenly on the working face, find out the flatness with a ruler and control a certain degree of floodlight, then tamp it with a flat vibrator (thick flat vibrator) or manually, and finally smooth it with plaster. There can be no Mingshui in the plaster.
In the process of paving and pouring, attention should be paid to:
(1) The loose paving coefficient is the ratio of the paving height of the material to the actual height. According to the dry humidity of permeable concrete, it is generally between1.1~1.15.
(2) The vibration time of the plate vibrator should not be too long, so as to prevent segregation due to over-density.
(3) Due to the high porosity and fast water loss of permeable concrete, when the temperature is higher than 35℃, the construction time should be avoided at noon, which is suitable for construction in the morning and evening.
5. Health permeable concrete has similar properties to cement concrete, so when the temperature is high after paving is finished and the elevation and smoothness meet the requirements, in order to reduce water evaporation, plastic film should be covered immediately to keep water. Watering can also be used for maintenance. Watering and curing shall be started at 1d after pervious concrete pouring, and after 8 hours of high temperature. However, when spraying water, it is not advisable to spray water directly on the concrete surface with pressure water, but directly from top to bottom. All curing periods shall not be less than 7d, so as to gradually improve the strength during the curing period.
6. Apply transparent sealant. After the surface concrete is molded and dried, the transparent sealant is brushed for about 3 days to enhance durability and aesthetics. Prevent the pores of permeable concrete from being polluted for too long, which will block the pores.
Third,? Construction control
(1) requires the construction unit to understand and analyze the characteristics of the project, formulate the construction plan, abide by the relevant operating procedures, and the project department will conduct technical disclosure and training.
(2) Require the construction unit to do the preparatory work before construction, such as the required water and electricity supply, the construction of the engineering material stacking shed (the cementing material should have a waterproof shed); Construction machinery, trolleys, bricklaying tools, wood or section steel for formwork installation, etc. ; Site setting of mixing machinery, etc. A small horizontal mixer is used to mix permeable concrete, and the best setting scheme of the mixer is the middle section of the construction site. Because the color permeable concrete is hard concrete and its initial setting is fast, the transportation time should be shortened as much as possible. In order to prevent concrete from sticking to the construction site, a certain range of the lower part of the mixer needs to be reinforced with protective plates.
(3) Laying special permeable pipes, in addition to laying according to the requirements of drawings, must be connected with the original road drainage system and become a part of the road drainage system.
(4) The supervisor shall witness the construction, strictly require the construction unit to construct according to the mixture ratio, control the water cement ratio and the vibrating time, and the vibrating time shall not be too long to prevent the concrete from being too dense and isolated. Use flat vibrator or manual tamping, and do not use high-frequency vibrator.
(5) Supervise the construction unit to do a good job in the health preservation and finished product protection of colored concrete. The curing time should be determined according to the construction temperature. The general curing period is 14 ~ 2 1d, the high temperature is not less than 14d, the low temperature is not less than 2 1d, and the curing period is not less than 28d. Traffic can only be opened after health preservation is completed.
Permeable concrete floor is a new type of ecological road material, which has the advantages of good permeability and durability. At the same time, it can also be said that it is a very good product, because it can be freely matched and adjusted. Now it is widely used in municipal engineering and landscape lighting pavement construction, but it is necessary to control the water-cement ratio and pay attention to pavement maintenance when constructing permeable concrete pavement. The above is the related content of pervious concrete floor compiled by Bian Xiao, and I believe it can help you.