Concrete applications i cimt 210

Pervious Concrete:What is Pervious?DefinitionHistoryApplications2. Stormwater ManagementBenefitsRecommended SpecificationsHydrologic Analysis3. Mix DesignCONCRETE APPLICATIONS I CIMT 2101. What is Pervious?DEFINITION (SEE VIDEO ON PERVIOUS CONCRETE) allows rainfall to be captured and to percolate into the ground.It reduces stormwater runoffIt recharges groundwaterIt supports sustainable construction What is Pervious?B. HISTORY not a new technology (first used in 1852)2. Federal Clean Water legislation (promotes it.)1. What is Pervious?C. APPLICATION Its high porosity provides is thermally insulating (i.e in walls of buildings) 2. It has good acoustical properties (for sound barrier walls). 1. What is Pervious?C. APPLICATIONTable . Applications for Pervious ConcreteLow-volume pavementsResidential roads, alleys, and drivewaysSidewalks and pathwaysParking areasLow water crossingsTennis courtsSubbase for conventional concrete pavementsPatiosArtificial reefsSlope stabilizationWell liningsTree grates in sidewalksFoundations / floors for greenhouses, fish hatcheries, aquatic amusement centers, and zoosHydraulic structuresSwimming pool decksPavement edge drainsGroins and seawallsNoise barriersWalls (including load-bearing)2. STORMWATER MANAGEMENTA. BENEFITSIts 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 regulations2. STORMWATER MANAGEMENTB. 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 MANAGEMENTB. 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 psiDrilled cores best measures in-place strengthsCompaction 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 MANAGEMENTB. Recommended SpecificationsFreeze –Thaw (continued)Research indicates that entrained air in the paste dramatically improves freeze-thaw protection  Sulfate ResistanceAggressive 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 DESIGNA. 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 cracking3. MIX DESIGNA. STRUCTURAL DESIGN Silica fume is a byproduct of silicone production. It consists of superfine spherical particles Used frequently for high-rise buildingsIt 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 landfilledThis material can be used to replace 5-65% of the Portland cementBlast 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.