Pervious concrete is also known as porous concrete or permeable concrete.
It is a particular type of concrete in which concrete flatwork utility allows rainwater to pass directly, thereby reducing runoff from a site and allowing groundwater recharge.
Earlier concrete is a mixture of cement with coarse aggregates and water with no fine combination or very small aggregates.
Introduction to previous concrete:
Previous concrete allows 50% infiltration while impermeable concrete allows only 15% and it has lighter densities of 15M to 1900 kg / m3.
Placement followed by a fog misting plastic, sheeting is the recommended for curing process for the last seven days, the implication of extensive concrete should replace sheeting.
Pervious concrete mix design:
- In the previous concrete the mixture has little or no good aggregate.
- The overall size is between 3/8 to 1/2 inch.
- Natural or crushed aggregate can be used.
- In general, round aggregates will require less condensation effort than crushed aggregates.
- They must be kept moist or wet, especially at high temperatures.
- Their aggregate to cement ratio typically falls between 4: 1- 5: 1.
Constituents of pervious concrete:
Cement is commonly used for the production of pervious concrete.
Complementary cementation materials such as fly ash or slag can be used for about 25% (fly ash) and 50% (slag) of cement.
Water meeting standard requirements for conventional concrete can be used to produce deformed concrete.
Water reducing admixtures may be used for lowering w/c ratio and increasing the strength of mortar.
Air entraining admixtures can be used to improve the freeze or melting durability of mortar.
Accelerating or retailing admixtures allows the setting properties of concrete to be adjusted in relation to ambient conditions.
Colour or pigment additives in powdered or liquid form can be used for the production of coloured pervious concrete.
Properties of Pervious concrete:
The compressive strength falls in the range of 3.5 MP to 28 MP, typical values are around 17 MPa.
Range between 1 and 3.8 MPa.
It is affected by degree of condensation, porosity, and aggregate-cement (A / C) ratio.
Depends on the properties and proportions of the material, condensation processes used in the placement.
In-place densities within the order of 1600 to 2000 kg/m^3 falls in the higher range of lightweight concrete.
This depends on the saturation level of voids in the concrete during the time of freezing.
Voids are saturated, complete freezing can cause serious damage.
Open and rough structure friction and bulge of aggregation on the surface can be a problem, therefore highways are generally not suitable for deformed concrete.
Advantage of pervious concrete:
- It reduces stormwater runoff replenishes water tables and aquifers.
- It eliminate detention ponds that are costly for stormwater management practices.
- Also permits for extra environment-friendly land growth.
- It prevents warm and polluted water from getting into streams.
- It minimizes flash flooding and standing water.
- Skidding is lowered.
- Light reflectivity is greater than asphalt surfaces, therefore reduce the heat island effect.
- Glare from the wet pavement is virtually eliminated.
Disadvantages of Pervious concrete:
- Runoff from adjacent areas onto pervious concrete needs to be prevented.
- The parking areas are generally limited to auto parking and occasional trucks.
- If reinforcement is required, epoxy-coated bars should be used.
- Concrete has variable permeability;
- Over-vibration significantly reduces permeability.
Applications of porous concrete:
The various uses of deformed concrete as follows:
- Residential roads, streets and driveways.
- Low-volume pavements.
- Sideways and avenues.
- Parking area.
- Tennis Court.
- Sub-base for traditional concrete pavements.
- In Well linings.
- Swimming pool decks.
Extensive concrete is mainly used for pavement construction.