subject: Roadbase Materials [print this page] Roadbase Materials Roadbase Materials
Queensland and Western Australia are the fastest growing regions in Australia. Any growing region requires infrastructure and connectivity to enjoy the benefits of a free flowing trade. It is therefore no surprise that road construction is being undertaken in a big way in and around Brisbane The largest city in Queensland and the hub of its economic activity.
Roadbase as the name suggests forms the base of roads. In plain terms it is the layer of aggregates under the paved layer of a road. These aggregates are essentially required to flatten the road path and also act as a binder to hold the sub-base. Another role of Road base is that of filler. Huge quantity of road base material is being used for major highways as well as smaller roads and pathways.
There are many types of Roadbase materials that are used. It could be natural sand and gravel, virgin quarry road bases or recycled road bases. Virgin quarry road bases had been the predominant choice but in recent times there has been a conscious shift towards finding more environmentally sustainable alternatives in the field of road base materials. The primary driver is the fast depleting natural sources of rock quarries and the challenges that the depletion of such resource pose to climate change and the overall eco-system at large.
As mentioned earlier virgin quarry aggregates were a very popular choice for road base material. The advantages they offered were they retained most of the properties of the rocks from which these were grinded. They were strong, natural binders and had excellent heat resistant properties. The biggest advantage they possessed was that they required the least treatment or refining before usage. In most developing economies they still are the preferred choice as the startup costs for alternatives like concrete recycling or crushed glass proved to be a deterrent. Typically lower qualities of recycled products also were inferior in terms of strength and binding.
Later on developed markets started using modified road bases. Roadbases basically consist of small granular stones which when correctly placed and compacted form a stiff pavement layer. Research in this area highlighted that to enhance stiffness binding agents could be added. Herein originated the modified road bases. These typically have a small amount of a binding agent such as lime added in them. There are other stabilized' road bases, which have larger quantities of binding agents such as cement, fly ash or slag. These further improved the quality of road bases and eventually of the roads.
With improvements in technology it became possible to refine and treat recycled slag to such an extent that it could match the properties of virgin quarry. In fact it had its own advantages apart from being environment friendly. The recycled road bases often are lower in density hence lesser quantity is required to fill the same surface area. They also have distinct advantage of lower transportation cost as often the demolition materials can be recycled and used. Crushed glass is another important ingredient in many recycled road base material.
Roadbase materials have come a long way and now most developed economies have clearly indicated their preference for recycled road base material. The primary reason is the impact quarrying of rocks has o the environment, also with technological advancements the gap between natural road bases and aggregates and recycled alternatives has narrowed down. The recycled road base material also acts as a natural waste disposal or land fill which simply adds to its appeal. However incase of specific roads we might still need virgin quarry aggregates. It's still a case of different horses for different courses.
