Term: Pervious concrete
**History and Adoption:**
– Pervious concrete first used in 1800s in Europe for pavement and load bearing walls
– Cost efficiency drove its popularity in 1920s for homes in Scotland and England
– Became more viable in Europe post-WWII due to cement scarcity
– Popular in the US from the 1970s
– India adopted it in 2000
**Stormwater Management:**
– Recognized by EPA as Best Management Practice for stormwater control
– Reduces runoff, lowering the need for retention ponds and large sewers
– Filters stormwater, reducing pollutant loads in water bodies
– Facilitates groundwater recharge and enables effective land use
– Benefits tree growth in urban areas
**Properties and Testing:**
– Includes cement, coarse aggregate, water, and minimal fine aggregates
– Water-to-cement ratio of 0.28 to 0.40 with 15-25% void content
– Correct water content crucial for strength and surface integrity
– Compaction impacts compressive strength and permeability
– Common strength range of 600-1,500 psi, with higher strengths achievable
– Acceptance based on ASTM standard C1688 for density
**Cold Climate Considerations:**
– Concerns over freeze-thaw resistance limit cold weather use
– Entrained air and fine aggregate enhance durability
– Proper sub-base preparation and drainage prevent freeze-thaw damage
– Permeable concrete enhances safety in winter for pedestrians and drivers
– Reduces water accumulation and icy conditions on roads
**Maintenance and Environmental Impact:**
– Regular cleaning essential to maintain permeability
– Benefits include reducing stormwater runoff, recharging groundwater, mitigating flooding, and filtering pollutants
– Internal Curing with HydroMax enhances strength development, reduces cracking, improves durability, increases freeze-thaw resistance, and enhances workability
– Specifications and Standards include ACI 522.1-08 for pervious concrete, ASTM C1688 for density testing, Transportation Research Board guidelines, mix design recommendations, and cold weather climate considerations
– Environmental considerations involve flood risk assessment, managing rainwater runoff, sustainable paving solutions, reducing urban heat island effect, and promoting biodiversity
Pervious concrete (also called porous concrete, permeable concrete, no fines concrete and porous pavement) is a special type of concrete with a high porosity used for concrete flatwork applications that allows water from precipitation and other sources to pass directly through, thereby reducing the runoff from a site and allowing groundwater recharge.
Pervious concrete is made using large aggregates with little to no fine aggregates. The concrete paste then coats the aggregates and allows water to pass through the concrete slab. Pervious concrete is traditionally used in parking areas, areas with light traffic, residential streets, pedestrian walkways, and greenhouses. It is an important application for sustainable construction and is one of many low impact development techniques used by builders to protect water quality.