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What is Bitumen and How is it Made?

Posted by Shell Zhang on

Origins Bitumen is defined in the Oxford English Dictionary as ‘a tarlike mixture of hydrocarbons derived from petroleum naturally or by distillation, and used for road surfacing and roofing’ (Oxford University Press, 1996). It is widely believed that the term bitumen originated in the ancient and sacred language of Hindus in India, Sanskrit; in which jatu means ‘pitch’ and jatu-krit means ‘pitch creating’. These terms referred to the pitch produced by some resinous trees. The Latin equivalent is claimed by some to be originally gwitu-men (‘pertaining to pitch’) and by others to be pixtu-men (‘bubbling pitch’), which was subsequently shortened...

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Who Were The Three Greatest Road Engineers?

Posted by Shell Zhang on

Jack Metcalf John Metcalf was the first of the great road builders during the Transport Revolution.  He was a remarkable man, who had been blind since the age of six, but went on to build about 300 km of turnpike road, mainly in Lancashire, Derbyshire, Cheshire and Yorkshire, in the period 1765 – 1792. His nickname was ‘Blind Jack Metcalf’. Metcalf believed that a good road should have good foundations, be well drained and have a smooth convex (rounded) surface to allow rainwater to drain quickly into ditches at the side of the road.   Metcalf established his reputation as a...

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10 Most Common Types of Asphalt Concrete Maintenance Treatments and Terminology

Posted by Shell Zhang on

Crack repair with sealing: A localized treatment method used to prevent water and debris from entering a crack, which might include routing to clean the entire crack and to create a reservoir to hold the sealant. It is only effective for a few years and must be repeated. However, this treatment is very effective at prolonging the pavement life. This method includes the following three crack repair methods : Clean and seal: Used on all types of cracks, it involves using a hot air lance or compressed air to blow out the debris in the crack, then filling with a sealant. Saw and seal: Involves...

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The Three Most Common General Pavement Maintenance Practices

Posted by Shell Zhang on

Increasing budget constraints require that states and local agencies perform more work with less money. Historically, the emphasis of local highway departments has been on building new roads, but the new focus is on maintaining and preserving existing pavement surfaces. This shift has resulted in three types of pavement maintenance operations: Preventative Maintenance A preventive maintenance program is a systematic approach to using a series of preventive maintenance treatments over time. A single treatment will improve the quality of the pavement surface and extend the pavement life, but the true benefits of pavement maintenance are realized when there is a consistent schedule for performing the preventive maintenance....

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Why does Asphalt Crack? What are the Factors and Hazards?

Posted by Shell Zhang on

The properties of asphalt pavement allow it to expand and contract with fluctuations in the material temperature. However, extreme cold temperatures can cause asphalt pavements to contract to a point that exceed the material’s elastic capabilities, resulting in thermally cracked pavements. If these cracks are left untreated, the asphalt layer, granular base, and lower soil layers are susceptible to damage from water that infiltrates the crack. Water can “strip” the asphalt binder from the sides of the crack, weakening the pavement structure. Water can also increase the moisture content of the granular base and subgrade soils, thereby weakening the foundation...

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