Posted by Jesse Willoughby on Wed, Jul 21, 2010 @ 02:29 PM
I just want to share a video I came across on Youtube today. What do you think about turning our roads into a power grid? This idea would create jobs and no doubt improve the roads we are driving on.
Click here to watch this asphalt solar road video on Youtube. Let me know your thoughts. Would you vote for this?
Posted by Jesse Willoughby on Mon, Sep 14, 2009 @ 02:24 PM
Sometimes Asphalt is better than concrete, and life-cycle costs can be one of those benefits where you'll save money.
- Reduces costs for initial construction.
- Requires less maintenance over the life of the pavement.
- Repaired and maintained cost-effectively with HMA overlays instead of complete removal and reconstruction with concrete.
- When maintenance is needed, HMA offers the widest variety of alternatives geared to solve the precise problems on the surface.
- Can be overlaid to add structural capacity to account for increased traffic loading.
- Eliminates the need for costly reinforcing materials, which are subject to corrosion, which lead to more frequent and more costly repairs.
- Properly designed and constructed HMA pavements will last 50 years or more with occasional resurfacing, relieving road agencies of the need for costly, time-consuming and disruptive reconstruction.
- HMA can be recycled (milled and replaced along with fresh materials), saving dollars and preserving nonrenewable natural resources.
Posted by Jesse Willoughby on Thu, Apr 23, 2009 @ 06:33 AM
Image: Hydrograph comparison showing how porous pavement reduces peak flow and total volume of runoff
Source: Cahill Associates
Impact on groundwater
Asphalt pavements are compatible with clean water. Studies show that asphalt pavements and stockpiles of reclaimed asphalt pavement do not leach.
Contaminants on the surface of pavements tend to become part of runoff, but with a porous pavement, they are washed into the stone bed. From there they flow down into the soil, where beneficial bacteria and other natural processes cleanse them. Data are limited, but indicate a very high removal rate for total suspended solids, metals, and oil and grease.
Figure 1 shows the effect of a porous asphalt pavement on the hydrology of a developed site.
Cool cities
Porous asphalt pavements have been shown to mitigate the urban heat island effect. Open-graded asphalt roads and highways-which use the same surface material as porous parking lots-have been shown to lower nighttime surface temperatures as compared to impervious pavements. In at least one city, the hottest heat signature is at the airport, with its thick, dense, impervious runways.
Comparisons to other asphalt pavements
The surface of a porous asphalt pavement wears well. While slightly coarser than some pavements, it is attractive and acceptable. Most people driving or walking on the pavement will not notice (or believe) that it is porous.
Like all asphalt pavements, porous pavements are ADA-friendly.
Environmental applications
Asphalt pavements have been used for many years to enhance water quality. At landfills, asphalt liners and caps keep contaminants from leaking into groundwater. Drinking water reservoirs lined with asphalt pavement have been used in California since the 1950s. Salmon hatcheries and fish rearing ponds in the Pacific Northwest use asphalt liners.
Variations on the theme
Porous asphalt can be used successfully in parking lots, walkways, and playgrounds. Several current suburban projects are exploring its use in subdivision roads. A few porous highways and city streets have been constructed, both in the U.S. and in Europe, and have performed well.
The open-graded asphalt surface used for porous pavements has been used extensively to surface high-volume highways that carry heavy trucks. Its benefits include noise reduction, a decrease in splash and spray kicked up by vehicles in heavy downpours, and mitigation of the urban heat island effect.
Posted by Jesse Willoughby on Wed, Apr 22, 2009 @ 06:25 AM
Construction and performance
Porous asphalt pavements are fast and easy to construct. With the proper information, most asphalt plants can easily prepare the mix and general paving contractors can install it.
The stone bed, often eighteen to thirtysix inches in depth, provides a tremendous subbase for the pavement. As a result, porous asphalt pavements tend not to exhibit cracking and pothole formation problems. The surface wears well. Under the stone bed is a geotextile which keeps fine particles from moving into the stone bed from below and filling in the spaces.
Porous asphalt has been proven to last for decades, even in extreme climates, and even in areas with many freeze-thaw cycles. The underlying stone bed can also provide stormwater management for adjacent impervious areas such as roofs and roads. To achieve this, stormwater is conveyed directly into the stone bed, where perforated pipes distribute the water evenly.
Economics
Porous pavement is a sound choice on economics alone. A porous asphalt pavement surface costs approximately the same as conventional asphalt. Because porous pavement is designed to "fit into" the topography of a site, there is generally less earthwork. The underlying stone bed is usually more expensive than a conventional compacted sub-base, but this cost difference is offset by eliminating the detention basin and other components of stormwater management systems. On projects where unit costs have been compared, the porous pavement has been the less expensive option. Porous pavements are therefore attractive on both environmental and economic grounds.
An installation at the University of North Carolina in Chapel Hill included parking lots where some sections were constructed from porous asphalt and others used porous concrete. The cost differential was approximately 4:1 - that is, the porous concrete pavement cost four times as much as the porous asphalt pavement.
Posted by Jesse Willoughby on Tue, Apr 21, 2009 @ 12:55 PM
Porous asphalt...
• Conserves water
• Allows for better use of land
• Reduces runoff
• Promotes infiltration
• Cleans stormwater
• Replenishes aquifers
• Protects streams
Porous asphalt offers a powerful tool in the toolbox for storm-water management.
In the natural environment, rainfall sinks into soil, filters through it, and eventually finds its way to streams, ponds, lakes, and underground aquifers. The built environment, by way of contrast, seals the surface. Rainwater and snowmelt become unoff which may contribute to flooding. Contaminants are washed from surfaces directly into waterways without undergoing the filtration that nature intended.
For these reasons, managing stormwater is a significant issue in land use planning and development. Stormwater management tools can serve to mitigate the impact of the built environment on natural hydrology. Unfortunately, however,they also can lead to unsound solutions such as cutting down stands of trees in
order to build detention ponds.
Porous asphalt pavements allow for land development plans that are more thoughtful, harmonious with natural processes, and sustainable. They conserve water, reduce runoff, promote infiltration which cleanses stormwater, replenish aquifers,
and protect streams.
A typical porous pavement has an opengraded surface over an underlying stone recharge bed. The water drains through
the porous asphalt and into the stone bed, then, slowly, infiltrates into the soil. If contaminants were on the surface at the time of the storm, they are swept along with the rainfall through the stone bed. From there they infiltrate into the subbase so that they are subjected to the natural processes that cleanse water.
Posted by Jesse Willoughby on Tue, Apr 21, 2009 @ 12:49 PM
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Posted by Jesse Willoughby on Mon, Feb 09, 2009 @ 04:16 PM
Pavements constructed of Hot Mix Asphalt (HMA) are so versatile that they can be used in practically every
situation. Consider these examples of the versatility of HMA pavements:
• In parking lots, HMA pavements are durable and economical.
• On interstate highways, HMA pavements stand up to high speeds and heavy trucks.
• In ports and log yards, new types of heavy-duty HMA pavements stand up to static loads.
• On city streets, HMA pavements are cost-effective, durable, safe, and quiet.
• When building a new neighborhood or shopping center, staged construction can be used to provide a durable
pavement during construction, and then topped with a pristine layer of asphalt for a beautiful street that will last
for many years.
The driving surface of an HMA pavement can be customized to
• minimize rutting,
• increase skid resistance,
• lower the risk of hydroplaning,
• decrease splash and spray, or
• absorb noise.
Environmental benefits
Asphalt pavement is America's most recycled product. And asphalt pavements have many environmental uses,
including:
• liners for reservoirs and fish hatcheries,
• caps for landfills, and
• biking/hiking trails that enhance our access to the outdoors while reducing damage to fragile ecosystems.
New technology
HMA offers state-of-the-art technology. New, specially designed pavement types include Superpave, SMA
(Stone Matrix Asphalt), OGFC (Open Graded Friction Course), high-modulus HMA, dense-graded HMA, HMA
with modified binders, and thin-friction lifts.
Easy maintenance
HMA pavements are easy to preserve and maintain because the top layer can be milled off for recycling, then
replaced with a new, durable pavement. On commuter routes, all the work can be done overnight, so that most
motorists are not inconvenienced by construction delays.
Posted by Jesse Willoughby on Thu, Jan 15, 2009 @ 12:17 PM
Pothole repair options have increased tremendously from a variety of types and sizes of equipment and proprietary mixes to help repair potholes faster, better, more safely, and more affordable. But when speed isn't the essence, and problems are deeper, and you want the BEST QUALITY you can have, you need to remove and replace the pavement. Here is how to construct the perfect patch.
1. Mark 1 foot into the sound pavement around the pothole. Sawcut a clean cut.
2. A vertical edge and right angles assure a sound patch. Once cut, break out and remove pavement within the sawcut area.
3. Remove material, including subgrade, until you reach a firm base. Compact. The Asphalt Handbook says deep patches can be backfilled with dense-graded mix.
4. Once compaction of the base and/or subbase is complete, apply a tack coat to the vertical sides of the cut. This helps it bond.
5. Place hot mix into the sawcut area. Rake or lute to level out the mix.
6. If placing mix in multiple layers, compact each layer after it is placed and leveled.
7. Add hot mix so the repair is slightly higher than the surrounding pavment (1/2 inch for a 2-inch deep repair is a good rule of thumb).
8. Sweep scattered mix onto the patch, then lute and level before final compaction.
9. Compact from the outside edges in toward the center of the repair. The next two passes here will be perpendicular to those already made.
10. Finish Compacting the entire patch. Vibratory plates are as effective as rollers. The size of the area to be compacted is the main determiner for whether compaction plates or rollers are used.
11. The end result of this step-by-step process is a structurally sound patch in which damaged pavement has been removed and overall pavement strengthened.