CONCRETE APPLICATIONS I CIMT 210 Pervious Concrete: What is Pervious? Definition History Applications 2. Stormwater Management Benefits Recommended Specifications Hydrologic Analysis 3. Mix Design

1. What is Pervious? DEFINITION (SEE VIDEO ON PERVIOUS CONCRETE) It allows rainfall to be captured and to percolate into the ground. It reduces stormwater runoff It recharges groundwater It supports sustainable construction http://asusmart.com/blog/news/asu-art-museum-pervious-parking-lot http://youtube.com/watch?v=G6BOJ6AFhls

1. What is Pervious? B. HISTORY Its not a new technology (first used in 1852) 2. Federal Clean Water legislation (promotes it.) http://www.perviouspavement.org/?gclid=CLG3wNr-so8CFQ4SQQodmStrMQ

1. What is Pervious? C. APPLICATION 1. Its high porosity provides is thermally insulating (i.e in walls of buildings) 2. It has good acoustical properties (for sound barrier walls). http://www.perviouspavement.org/?gclid=CLG3wNr-so8CFQ4SQQodmStrMQ

1. What is Pervious? C. APPLICATION Table . Applications for Pervious Concrete Low-volume pavements Residential roads, alleys, and driveways Sidewalks and pathways Parking areas Low water crossings Tennis courts Subbase for conventional concrete pavements Patios Artificial reefs Slope stabilization Well linings Tree grates in sidewalks Foundations / floors for greenhouses, fish hatcheries, aquatic amusement centers, and zoos Hydraulic structures Swimming pool decks Pavement edge drains Groins and seawalls Noise barriers Walls (including load-bearing)

2. STORMWATER MANAGEMENT A. BENEFITS Its subbase may provide enough water storage capacity to eliminate the need for retention ponds, swales, and other precipitation runoff containment strategies. 2. Its drainage media for hydraulic structures, parking lots, tennis courts, and greenhouses. 3. It helps owners comply with EPA stormwater regulations

2. STORMWATER MANAGEMENT B. Recommended Specifications  1. Recommended Concrete working time is usually, one hour between mixing and placing. 2.Using retarders and hydration stabilizers can extend the working time by as much as 1.5 hours   (Density and Porosity) .A pavement 5 inches (125 mm) thick with 20% voids will be able to store 1 inch (25 mm) of a sustained rainstorm in its voids. It covers the majority of rainfall events in the U.S. 6-inch thick subbase of open-graded gravel increases it to as much as 3” of precipitation                                                                   

2. STORMWATER MANAGEMENT B. Recommended Specifications   (Permeability)  Typical flow rates through pervious concrete are 3 to 8 gal/ft²/min, rates of up to 17 gal/ft²/min   (Compressive Strength)  Compressive strengths ( 500 to 4000 psi) Typical values are about 2500 psi Drilled cores best measures in-place strengths Compaction differences make cast cylinders less representative of field concrete. (Flexural Strength)  Flexural strength (150 psi to 550 psi ). Flexural strength is affected by compaction, porosity, and the aggregate-to-cement (A/C) ratio. Pervious concrete does not require the measurement of flexural strength for design.

2. STORMWATER MANAGEMENT B. Recommended Specifications Freeze –Thaw (continued) Research indicates that entrained air in the paste dramatically improves freeze-thaw protection   Sulfate Resistance Aggressive chemicals in soils or water, such as acids and sulfates, are a concern to conventional concrete and pervious concrete Abrasion Resistance  Because of the rougher surface texture and open structure of pervious concrete, abrasion and raveling of aggregate particles can be a problem, particularly where snowplows are used to clear pavements. Highways are generally not suitable for pervious concretes. However, anecdotal evidence indicates that pervious concrete pavements allow snow to melt faster, requiring less plowing.

3. MIX DESIGN A. STRUCTURAL DESIGN Cementitious materials Portland Cements (ASTM C 150, C 1157) Blended cements (ASTM C 595, C 1157) Fly Ash, pozzolans (ASTM C 618) Ground-granulated blast furnace slag (ASTM C 989)  Supplementary cementitious materials (SCMs) Fly ash, pozzolans, and Slag These influence concrete performance, setting time, rate of strength development, porosity, permeability, etc.   Silica fume, Fly ash, and Blast furnace slag all increase durability by decreasing permeability and cracking

3. MIX DESIGN A. STRUCTURAL DESIGN Silica fume is a byproduct of silicone production. It consists of superfine spherical particles Used frequently for high-rise buildings It produces concrete that exceeds 20,000 psi Silica fume can replace 5-12% cement Fly ash is the waste byproduct of burning coal in electrical power plants;it used to be landfilled This material can be used to replace 5-65% of the Portland cement Blast furnace slag is the waste byproduct of steel manufacturing. It imparts added strength and durability to concrete, and can replace 20-70% of the cement in the mix.