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This article highlights the benefits of designing parking lots with concrete, including established rational design, low maintenance, long life, safety features, lower ownership costs, and environmental friendliness. It also compares concrete and asphalt pavements and provides a sample parking lot comparison.
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Design Benefits • Established rational design - ACI 330 • Integral curb and gutter • Fewer drainage structures needed • Can be easily designed to hold storm water • Can be colored and textured to owner’s desires
Maintenance • Proven fewer repairs • No annual resealing needed • Low annual maintenance cost • No business interruption
Performance • Proven long life • Strength increases with age • Evenly carries heavy loads • No potholes, bumps, or wrinkles • Resistance to freeze-thaw
Safety • Excellent light reflectance • Greater visibility • Rigid pavement means no potholes • High skid resistance • Less ponding means less re-freezing and less exposure to liability in cold weather climates
Lower Total Ownership Costs • Competitive first cost • Proven longer life • Lower life cycle costs • Predictable cost estimates • Energy Costs • Less lighting needed • Savings as great as 30% • Low heat absorption • 7° - 10° F cooler ambient air temp • Lower cooling costs
Environmentally Friendly • Uses less raw materials • No hazardous materials used • Recycled materials can be used • Conserves petroleum resources • Does not pollute waterways
Compare Concrete and Asphalt • Portland Cement Concrete • Hot Mix Asphalt • Formerly known as Bituminous Concrete • Both use sand and stone • How these raw materials are bound together make the difference
Portland Cement Concrete • Industrial strength glue as binder • Inorganic – Does not break down • Gains strength over time • Creates a rigid pavement • Able to evenly carry loads • Low maintenance
Hot Mix Asphalt • Uses “Scotch-tape like” adhesive for binder • Requires pressure (compaction) • Petroleum-based organic adhesive – breaks down due to heat, water, & UV rays • Becomes weaker over time • Requires costly seal coats & overlays to replenish this “adhesive” • Creates a flexible pavement • Strength and durability highly reliant on quantity and quality of base material • Results in high maintenance costs
6,600 lbs 6,600 lbs pressure < 29 psi pressure » 290 psi Concrete’s rigidity spreads the load over a large area and keeps pressures on the subgrade low. Pavement Failure • Not due to # of years • Due to stress of vehicle traffic Concrete Asphalt
Concrete vs. Asphalt • Apples-to-apples comparison of pavement design should always be considered • It takes 8” or more of asphalt to equal load carrying capacity of a 5” concrete pavement
Sample Parking Lot Comparison • Utilizing NRMCA Concrete Pavement Analyst • 100,000 ft2 • Average daily truck traffic (ADTT) 25 • Subbase soil type - Common - CBR 3 • Planned service life 20 years