Posted on March 15, 2018
Should your new parking lot be surfaced with asphalt or concrete? There are many reasons to seriously consider concrete, from economic to environmental and from aesthetic to functional. Here are five key reasons why an investment in a concrete parking lot makes sense.
Simply put, when subjected to significant loads, asphalt flexes much more than concrete does. Concrete disperses loads across a greater area, reducing base layer loads. It possesses a higher layer coefficient than asphalt. Asphalt flexes to the point that it decreases load dispersals, and this increases base layer loads. The only way to properly cope with this is to increase base layer thickness, alter base layer composition or both.
When it comes to asphalt, resilience concerns multiply when temperatures are extreme. Asphalt softens in extreme heat, and it can contract to the point of cracking in extreme cold. Triple-digit temperatures in summer heat waves may soften asphalt enough to compromise its load-bearing capabilities, leading to premature deterioration of the asphalt and/or the base layer.
2. Lifecycle Costs
In most instances, life cycle cost analyses favor concrete over asphalt. The scales tip even further in favor of concrete when environmental lifecycle costs are also considered.
As MIT's Concrete Sustainability Hub notes, a proper life cycle cost assessment (LCCA) must consider all costs from "initial construction to demolition," including factors like lighting requirements and long-term maintenance. Environmental analysis should consider everything from the acquisition of materials to the use phase and on to eventual disposal costs. A thorough LCCA provides designers, engineers, decision makers and stakeholders with the information they need to make informed infrastructure decisions that balance costs, risks and impact.
Albedo is a measure of the amount of solar energy that a given surface reflects. Relatively high albedo surfaces like concrete reflect more solar energy, while low albedo surfaces like asphalt absorb more solar energy, increasing the heat felt by visitors on warm, sunny days.
Convenience stores and gas stations have increasingly turned to concrete to create well-lit, safe and energy-efficient oases for their endless flow of customers.
In general, asphalt lots are costlier to maintain. Asphalt preservation requires periodic seal coating. As asphalt lots age, spider cracks, potholes and rutting may proliferate. These flaws may even increase the relative toxicity of water runoff. Therefore, crack and pothole repairs are often necessary. Periodic milling and resurfacing are frequently required to restore a level, consistent surface.
Also, deterioration of the base layer may eventually require comprehensive lot reconstruction. In busier settings, seal coating and repairs may cause logistics problems or business interruptions.
Concrete is often much simpler to maintain. Joint sealing, striping and an occasional repair are all that is typically required. The lower cumulative maintenance costs of concrete make it an attractive alternative. There are also aesthetic considerations -- concrete sends a positive message to arriving customers and visitors about your brand, and it looks good throughout its life cycle.
5. Price Stability
To understand the comparative stability of asphalt and concrete prices, consider the cost of their respective raw materials -- oil vs. silica and fly ash. The volatility of oil prices is well known. For example, over the past five years, WTI crude oil prices have ranged from less than $30 to more than $110 per barrel. A BLS graph published by MIT reveals how much asphalt has soared in price relative to concrete and steel since 2005.
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