Always Advancing Pervious Pervious challenges: Build tougher pavement. Build pavement that drains well. We can identify the challenge of building pervious concrete pavement that is more durable and will drain well. Our design and construction methods can advance mixtures and finishing methods. Our systems can be designed to be maintenance friendly by observing the specific unique functions of pervious concrete pavement in the practice of storm water management.

intro David Mitchell Bunyan Industries Equipment manufacturer Allied with NRMCA and promoters of cement and ready mixed concrete System designs Hydrology Mixture variations Hi, I’m David Mitchell from Bunyan Industries. We previously covered mixtures and surface finishes. This section will cover the system design, site conditions and the outfalls that serve our hydrologic function.

objectives Evaluate the potential site and the owner site terrain geotechnical properties of site soils site precipitation flow in/out mixture design detention design landscape adjacent pavement traffic exposure to deicing salts Every site is different. Each has potential advantages and certain limits. The system designer should evaluate the site and apply certain features of the system to best serve the expectations of the owner.

objectives Educate the owner to expect: differences in storm water function porous surface texture award contracts based on experience tasks of guarding against deicing salts tasks of guarding from contamination tasks of prompt and proactive response tasks of monitoring infiltration rates tasks of regularly scheduled cleaning tasks of remedial extraction tasks of applying denisifiers and sealers Those responsible for system design should also align the owner’s expectation of unique performance and the unusual tasks of protecting and maintaining the entire system. The pervious concrete storm water system should be designed to make each of these tasks easier and more effective. The potential owner of this pavement should understand that the system will not continue to function unless it drains well and is guarded against certain types of contamination.

Site conditions Permeability of soils at basin Permeability of soils at 15 ft depth Slope Elevation: slab section detention basin detention water at maximum Precipitation Potential inflow of water / silt Discharge limits & fees for outflow Use software called Pervious Concrete Hydrological Design to apply the variables of perc rate, precipitation rate for the pavement areas and include the areas which flow into the system. This will calculate the required thickness for detention basin aggregate. If the soils and water table will allow, an injection column may be installed to vent additional infiltration through shallow, impermeable soils.

Perimeter curb . The slab section is surrounded by curbs of various type, intended to protect the pavement from surrounding areas. The curb also blocks the migration of surrounding soils into the voids of the detention aggregate. The edges of the detention aggregate are also isolated with a vertical silt barrier which is folded to form an “L” shape. The horizontal silt barrier is best achieved by placing a layer of coarse sand at 4 to 6 inch depth at the bottom of the detention basin aggregate. An alternate design may use filter fabric as a horizontal silt barrier but has historically shown to clog with silt.

slope . Choose a slab elevation that is slightly higher than the surrounding terrain. A simple system is level. If slope is required, excavate the bottom of the detention basin to a level surface, install the vertical silt barrier around the perimeter. Secure the top edge of the vertical barrier to the formwork to remain at slab elevation. Install a level horizontal silt barrier. Fill the basin with detention aggregate to the bottom of the slab section.

Adjoined to asphalt .

Check dam .

Multi-layered pavement can reach multiple objectives. Alternate vents Multi-layered pavement can reach multiple objectives.

Tree wells

Exposed edge

Filter Fabric Examine a sample of detention aggregate that is infiltrated with water. Silt can develop clogging on the fabric surface. This is the main reason to use a layer of sand to build a horizontal silt barrier, rather than filter fabric. We refer to this as “planar occlusion

Water of convenience Water of necessity waters Water of convenience Water of necessity

Structure Bridge formation Absorption Wet, metallic sheen Structure Bridge formation Absorption

Structure Bridge formation Absorption Wet, metallic sheen Structure Bridge formation Absorption

Particle packing Particle sizes: cement slag coal ash silica fume nano silica Entrained air Paste density

Surface Exposure Wind Relative humidity Moist cure Surface Exposure Wind Relative humidity

Fog Evaporation inhibitor Curing compound Poly sheeting Moist cure Fog Evaporation inhibitor Curing compound Poly sheeting

Super Absorbent Polymer  

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