The History of Bitumen Asphalt Concrete Roads

The History of modern road construction and paving materials dates back to the days of the late1900s when it became widespread, the chief paving materials of the day consisted of loose gobble stones and blocks in addition to miscellaneous wooden bricks, blocks, crushed rocks and pebbles, and at times some naturally occurring tar and cement concrete surfacing materials were also used. John Mc Adam the inventor of crushed rock (road metal) and his broken stone design provided the most cost effective paving options, at the time but its open cut surface was inapt to sustain the viability of road constructions and consequently became to consist of slippery and muddy road surfaces once bought on by wet weather conditions and abundant amounts of horse excrement. At the start of the 20th century, roads were mostly inadequate to cater for the every day traffic demands which were going to be challenged increasingly by the newly invented motorcar. As time went by and the motor car technology developed and vehicle velocities increased, the friction between the road surfaces and the car tires became a critical road safety issue especially when subjected to stresses encountered when subjected to constant acceleration, cornering and braking conditions. In addition to numerous pavement failures experienced at the time it was also made apparent that much more durable and tougher road construction materials were called for. The answer at the time was relying in the ongoing research which was being conducted to find better, cheaper and stronger road pavement materials and processes that could withstand the hustle and bustle of every day road traffic and roads made from Asphalt and cementic concrete seemed to offer the most promise. Asphalt is generally a mixture of bitumen and aggregates namely crushed rock as cementic concrete is also a mixture of cement and rock, asphalt pathways were first paved in France in the early 1800's, but the method was not perfected until around 1829, The first use of roads constructed using asphalt and bitumen took place in around 1825, when asphalt blocks were first put down as a pavement on French streets in Paris, and the first successful great asphalt and bitumen (tar) paving application was first laid down in1858. The first successful paved cement concrete sidewalk in turn was built in Inverness in Scotland in 1865, neither technology however progressed greatly without the added pressures which the motorcar posed on the roads infrastructure in the coming years.

The History and advancement of the modern road asphalt as we see on our roads today came initially from the United States which had great naturally occurring bitumen deposits from which to draw from and where the local engineers were forced to analyze the principles behind the behavior of this promising new road engineering material. The first real initiative came in the late 1860s, from the research work conducted by a Belgian immigrant Edward de Smedt from Columbia University in New York City where De Smedt conducted his first field testing in New Jersey in 1870 and by 1872 was already producing the equivalent of a modern day maximum strength dense graded road asphalt. The first practical application was followed by the laying of asphalt in Battery Park and on Fifth Avenue in New York USA in 1872. De Smedt went later to Washington. D.C in 1876 as part of President Ulysses S. Grant's desire to make the city a Capital City deserving of a great Nation. President Grant assigned a commission to supervise the undertaking of a major road making project, and they went on to conduct first successful field trials on Pennsylvania Avenue in1877, sixty percent of the asphalt field trials at the time were being using based on de Smedt's new bituminous asphalt mixture which consequently went on to became a great successes. In 1887 de Smedt's foot steps as an inspector of asphalts and cements were keenly pursued by Clifford Richardson, who instigated the standardization and the specifications of asphalt mixes in the United States. Richardson developed two forms of asphalt, mainly bituminous dense graded asphaltic DGA concrete, which had great fatigue properties and therefore offered structural strength in a roller (compacted) asphalt design, which contained more than enough bitumen and therefore created a smoother and more effective surface for motor vehicle as well as for pedestrian traffic.

One of the great convenient coincidences in the history of asphalt roads was the development of the motor car which by pure chance ran on gasoline which at that time was just another petroleum by-product which was distilled from kerosene which in turn was derived from petroleum by the fast emerging and growing petroleum refining industry. Another useful by-product that was derived in the process of refining crude oil was bitumen, until that time most asphalt aggregate paving manufacturing had used coal tar as a binder for road asphalt construction which is a by-product of the petroleum refining process and coal tar in today's standards is considered a toxin and hazardous carcinogen. As the demand for motorcar fuel rapidly increased so did the availability of this highly sought after black sticky residue (bitumen) as did the asphalt roads that were designed and constructed jointly by de Smedt and Richardson. This gave U.S. road contractors a major advantage over their European counterparts, who were still hooked up with the virtues of the various naturally occurring asphalts such as those from Neuchatel, Switzerland, and from the island of Trinidad hence the term "lake asphalt" of which asphalt was widely used in the mastic asphalt paving and roofing industries around Europe and the U.S. Clifford Richardson went on to publish a standards based textbook on asphalt paving in 1905, and the practice from a major innovation point of view has never quite changed much from thereafter. The greatest change has occurred mainly in the machinery and equipment available to produce, lay, and finish asphalt roads, but not so much in the binder (bitumen) formulation itself which is required to hold the asphalt aggregate mix constituents together. Toward the end of the century, there were major advances towards the use of recycled asphalts, chemically modified for improving bitumen properties mainly the fatigue and durability characteristics, and fibers for improving things like crack resistance and rutting resistance, additionally the developments in structural analysis and testing made it possible to further design asphalt pavement constructions which would become advanced functional high load bearing structures as we basically see on our roads today. The first modem cement concrete roads in the road construction history were developed by a Civil engineer Joseph Mitchell, who conducted three successful field trials in England and Scotland in the years 1865 - 1866, Mitchell was also a keen follower of Thomas Telford, who was a stonemason, architect and civil engineer and a noted road, bridge and canal builder. Comparable to asphalt technology, cement concrete roads have been used since the dating back to the Roman days. the modern roads concrete built using cement was largely developed in the turn of the 20th century and was limited more by the availability of appropriate application machinery than by the cement material itself. Technical issues were experienced in constructing a surface that could compare with that of a properly constructed hot roller compacted asphalt. For the next 95 years the two competing materials have remained in fierce rivalry, both offering a similar product at a similar cost, and there has always been little evidence that one would move far in front of the other as they continued on their paths of gradual technological progress and improvement, at least not until the global climate change problem first hit the head lines and became a environmental concern in the 1990s and Ecopave Australia Bio-Bitumen Asphalt Concrete Research