Paved Surface
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Water Drainage: Two main water problems have an adverse impact on pavement lifespan; sub-surface water saturation, and insufficient surface drainage. The larger problem of the two is sub-surface water saturation where leaking irrigation or high water tables saturate support structure under the asphalt. This places load-bearing stress on asphalt, which leads to eventual failure of the asphalt and its base structure. These are extremely costly repairs that can be avoided through early identification and preemptive action.
It is very rare to install an asphalt surface that does not connect to existing driveways, roadways or parking lots. As such, asphalt-paving contractors must find a way to smooth the transition from old surface to new.
Paved surfaces get warmer in the summer than green space; removing paving creates more room for plantings and the plants keep the area cooler on hot summer days. Removing paving offers animals, plants and soil life more space.
In urban areas many surfaces are paved unnecessarily, often with the argument of lower maintenance costs. But unused paved surfaces must also be maintained: they must be swept and pesticides to fight weeds are often used. So the question is whether a low-maintenance field of wild grass that needs to be mowed only twice a year needs more maintenance.
Not only horizontal surfaces such as paving at ground level and roofs, but also vertical surfaces (facades, noise barriers) can be made permeable. In general, the following rule applies: the rougher the surface, the greater the effect. A field of flowers does more than a grass lawn, and bushes have a greater effect than a stand of herbaceous plants. The biggest effect on air quality is most likely through the reduction in the disturbance of precipitated particle matter. If there is a lack of space at ground level, green facades can be used. These contribute to the capture of particle matter, though mainly to the lowering of the atmospheric temperature.
The spread of impervious surfaces was widespread across the region, but development was particularly intense along key lines of transportation. Much of the development occurred along the Beltway in communities such as Tysons Corner, Springfield, College Park, and New Carrollton. Inside the Beltway, building followed the Metro rail lines.
At one time it was thought that a prime coat was an essential element of good pavement construction. However, in recent years some engineers have eliminated the use of a prime, especially when asphalt layer(s) (surface and/or base) is 4 inches or more in thickness. In many instances, prime coats have not been used even when surface thickness have been as thin as 2 inches. Over the past 20 years, few, if any, pavement failures can be attributed to the lack of prime coat.
Generally speaking, there are no unique problems with using polymer modified mixes as RAP. Some individuals express environmental concerns about running millings containing ground tire rubber (GTR) through a drum plant. Florida uses a small percentage of GTR on most of their highway surface mixes. California and Arizona also use GTR frequently.
We do not recommend spraying water on freshly laid hot mix asphalt (HMA) in order to cool the mat faster and open to traffic sooner. First, spraying water on the hot mat is not very effective since the water should drain properly on a new surface and only cools the crust temporarily, with the internal HMA temperature not being affected much. In addition, there is a concern that the water could cause a foaming effect with the hot asphalt binder, making the HMA less stable under traffic. We believe it is best to let the hot mat cool naturally.
The Asphalt Institute recommends a transverse slope of between 1.5 to 3.0% on all pavement surfaces, and an even steeper slope of 3 to 6% on shoulders. Maintaining a slope of at least 1.5% on parking lots will ensure proper surface drainage (no ponding or birdbaths) and minimize infiltration, hydroplaning and the detrimental effects of water.
It is not avisable to start paving if it is raining. If rain starts after paving has begun, the work can continue as long as there is no standing water and the rain is not too hard. The primary concern is achieving adequate compaction, as the mix will cool much faster due to evaporative cooling if laid on a wet surface or rain falls on an uncompacted mat. Additional compactive effort will be needed and monitoring temperatures is key to acheiving adequate density.
Generally speaking, there should be no unique problems with using polymer modified mixes as RAP. There have been some individuals express environmental concerns about running millings containing ground tire rubber (GTR) through a drum plant. Florida uses a small percentage of GTR on most of their highway surface mixes. California and Arizona also use GTR frequently.
This guide explains requirements in the ADAStandards for floor and groundsurfaces. Specifications for floor and ground surfaces address surfacecharacteristics, carpeting, openings, and changes in level. They applyto:
Accessible floor and ground surfaces must be stable, firm, and slipresistant. Stable surfaces resist movement, while firm surfaces resistdeformation by applied forces. Accessible surfaces remain unchanged byexternal forces, objects, or materials.
Accessible surfaces must be slip resistant to minimizehazards to people with disabilities, especially those who are ambulatoryor semi-ambulatory or who use canes, crutches, and other walking aids. However, the standards do not specify a minimum level of slip resistance(coefficient of friction) because a consensus method for rating slipresistance remains elusive. While different measurement devices andprotocols have been developed over the years for use in the laboratoryor the field, a widely accepted method has not emerged. Since ratingsystems are unique to the test method, specific levels of slipresistance can only be meaningfully specified according to a particularmeasurement protocol. Some flooring products are labeled with a slipresistance rating based on a laboratory test procedure.
The standards limit changes in level and openings in floor and groundsurfaces, but they do not further address overall surface smoothness. Rough surfaces composed of cobblestones, Belgian blocks, and similarmaterials can be difficult and sometimes painful to negotiate withwheeled mobility aids due to the vibrations they cause.
Concrete, asphalt, and other paved surfaces are more reliably compliant,but other materials, such as wood, and construction methods can be usedto provide firm and stable surfaces. Loose material like gravel willnot perform adequately unless it is sufficiently stabilized by binders,compaction, or other treatments and will likely require repeatedmaintenance.
The standards require ground and floor surfaces to be slip resistant,but they do not specify a minimum level of slip resistance orcoefficient of friction. This value varies according to the measurementmethod and protocols used. Some products are labeled with a ratedlevel, but in the absence of a consensus test procedure, the standardsdo not set a minimum value. Standard methods to prevent or minimizeslipperiness in the specification of floor materials, textures,applications, and finishes may be sufficient for compliance with thestandards.
Sprawl causes increased reliance on automobiles because suburban developments are spread over larger land areas. This results in more roads being built over larger land areas. Roads are impervious surfaces. Impervious surfaces prevent rain and other precipitation from naturally seeping into the ground. As a result, the building of roads may contribute to the pollution of the local waterways in a variety of ways:
One can walk on the new surface right away, it may stick to your shoes, but it is ok to walk to and from your destination. In hotter months, it is advisable to not park or drive on your new driveway for at least 3 days. In less hot months, one can stay off for 1 to 2 days.
Parking in one spot for a long period of time, on a freshly paved surface, is still not recommended to do for at least a week. Overtime, the asphalt will adjust to the enviornment and won't be as \"vulnerable\" to parking, turning wheels, draining of water, etc...
Using pavers for ground surfaces is a bit more expensive up-front but it has its advantages. Brick and paving units (usually made of precast concrete) have small spaces between them, which gives them the ability to conform to the ground as it shifts, unlike solid asphalt or concrete. If the ground becomes uneven to the point where the pavers are no longer level with each other, it can be a tripping hazard. Luckily, repairs are easy. Individual pavers can be removed and the base course (usually crushed gravel) can be smoothed out below before putting the pavers back in. If any of the pavers break, they can be taken out and replaced with new ones. No obvious repair patchwork means that surfaces with this type of paving will age gracefully and look like new for much longer.
Loose gravel surfaces for play areas or planting areas are usually made of larger, heavier particle sizes and are contained with solid borders like curbs to contain it, making them less susceptible to erosion. It is still more or less inevitable that some gravel will escape, requiring some occasional tidying with a broom to keep surrounding hard surfaces gravel-free. Twigs and other debris might find their way into gravel. These can be easily picked or raked out.
Debris accumulating on rubber surface(Image: James West ) Keeping the rubber clean lets this pattern shine(Image: Soft Surfaces Ltd ) Debris may accumulate in cracks, requiring a leaf blower or vacuum(Image: Nick Ares ) Leaves from nearby trees will find their way to any surface(Image: Scott Robinson ) 59ce067264