Problem 6 Like most civil engineering materials, asphalt concrete has upsides and downsides in terms of sustainability. The Calkins text outlines many of these in Chapter 8. Often, asphalt\'s downsides can be mitigated by alternative practices or materials Provide a discussion of one potential environmental issue related to asphalt (A)Discuss one aspect of traditional asphalt concrete that is unsustainable (environmentally, economically, etc.) (B) Discuss two potential means/methods for mitigating or eliminating the issue described in (A) Solution Asphalt concrete is extensively used to build roads. Asphalt concrete mainly contains asphalt which is used as a binder and some other aggregate of minerals. Asphalt layer is laid upon a base of gravel layer to construct a stiff and dependable road. Asphalt can be categorized into different categories depending on the laying temperature of the asphalt. advantages of asphalt :- Asphalt is used for highways having high volume of traffic. These roads are lower in cost and produce lower noise making it more suitable for regular usage with safety. It also offers higher traffic speed and is easy to repair as well disadvantages of asphalt :- However, Asphalt roads are less durable and become soft in hot weathers. Higher temperatures can soft down the asphalt binder making the roads softer. Thus a heavy load on such soft surface can deform the surface. However, very cold temperature can cause the contraction of asphalt resulting in the formation of cracks. Good maintenance can increase the durability of the roads. It also reduces the cost of repairing A and B he networks that tie our world together are indeed vast constructions, none more so than the roadways that tie our cities, towns and villages together. Roadways the world over are predominantly made of asphalt, an impervious, petroleum-based substance that includes aggregate such as sand or gravel. This same product is used in the installation of the expansive parking lots that characterize suburban development.What makes asphalt all the more problematic is the fact that water cannot pass through it. As a result, asphalt – in addition to paving the world over – not only dries out the ground below it, but gradually warms the environment in which it is used. Beyond ecological and aesthetic complexities, asphalt’s chemical makeup also represents a very real threat in both the short and long term. For one thing, asphalt has very high thermal mass properties through which it can retain heat generated from the sun. Said heat is slowly released from pavement over time, creating the heat island effect, which is responsible for increasing temperatures in some cities by as much as ten per cent relative to surrounding rural areas. Because asphalt is manufactured out of oil, moreover, it releases substantial volatile organic compounds (VOCs) during its production, including carcinogens benzene and toluene. Due to the intricate molecular structure of such compounds.

1. Problem 6 Like most civil engineering materials, asphalt concrete has upsides and downsides in
terms of sustainability. The Calkins text outlines many of these in Chapter 8. Often, asphalt's
downsides can be mitigated by alternative practices or materials Provide a discussion of one
potential environmental issue related to asphalt (A)Discuss one aspect of traditional asphalt
concrete that is unsustainable (environmentally, economically, etc.) (B) Discuss two potential
means/methods for mitigating or eliminating the issue described in (A)
Solution
Asphalt concrete is extensively used to build roads. Asphalt concrete mainly contains asphalt
which is used as a binder and some other aggregate of minerals. Asphalt layer is laid upon a base
of gravel layer to construct a stiff and dependable road. Asphalt can be categorized into different
categories depending on the laying temperature of the asphalt.
advantages of asphalt :-
Asphalt is used for highways having high volume of traffic. These roads are lower in cost and
produce lower noise making it more suitable for regular usage with safety. It also offers higher
traffic speed and is easy to repair as well
disadvantages of asphalt :-
However, Asphalt roads are less durable and become soft in hot weathers. Higher temperatures
can soft down the asphalt binder making the roads softer. Thus a heavy load on such soft surface
can deform the surface. However, very cold temperature can cause the contraction of asphalt
resulting in the formation of cracks. Good maintenance can increase the durability of the roads. It
also reduces the cost of repairing
A and B
he networks that tie our world together are indeed vast constructions, none more so than the
roadways that tie our cities, towns and villages together. Roadways the world over are
predominantly made of asphalt, an impervious, petroleum-based substance that includes
aggregate such as sand or gravel. This same product is used in the installation of the expansive
parking lots that characterize suburban development.What makes asphalt all the more
problematic is the fact that water cannot pass through it. As a result, asphalt – in addition to
paving the world over – not only dries out the ground below it, but gradually warms the
environment in which it is used.
Beyond ecological and aesthetic complexities, asphalt’s chemical makeup also represents a very
real threat in both the short and long term. For one thing, asphalt has very high thermal mass
properties through which it can retain heat generated from the sun. Said heat is slowly released
from pavement over time, creating the heat island effect, which is responsible for increasing

2. temperatures in some cities by as much as ten per cent relative to surrounding rural areas.
Because asphalt is manufactured out of oil, moreover, it releases substantial volatile organic
compounds (VOCs) during its production, including carcinogens benzene and toluene. Due to
the intricate molecular structure of such compounds, poisonous effects are very real long after
the release of VOCs from their points of origin. In other words, paved roads contribute to the
disintegration of safe, healthy environments in which acts as simple as breathing connote
veritable dangers
As mentioned, asphalt wreaks havoc on the way water interacts with its natural world. Normally,
rainfall is absorbed into the ground as it comes down from the sky, where is it either consumed
by plants or integrated into groundwater. As the latter accumulates, it transforms into rivers,
streams and lakes. Asphalt disrupts this process completely, as runoff finds itself diverted into
sewers where contact with VOCs is inevitable. Forever tainted, sewage water ends up
contaminating natural water sources, compromising the water cycle indefinitely.
Nonetheless, the vast asphalt cover represents an unprecedented opportunity to green cities,
simply by replacing pavement with trees, brush, and gardens. In fact, the pervasiveness of car
parks in proximity to dense population centres translates into the realistic goal of creating urban
agricultural hubs in cities around the world.
Furthermore, removing asphalt allows soil to absorb much needed rain and air, in turn enabling
plants to reach rich minerals deep beneath the ground, while stabilizing the water cycle. By
extension, if local agricultural practices are to take shape, it is first and foremost vital to end the
construction of roads, a process to be followed by the elimination of paved land in urban areas.