Essay On Asphalt

902 Words2 Pages

RAP There has been a drastic increase in the production of asphalt in Ireland in recent years. As a result of this increase in production the consumption of materials has also obviously increased however these materials, such as aggregate, tend not to be renewable. Increased consumption of any non-renewable resources will inevitably have to be addressed and one way of addressing this problem is the use of Reclaimed Asphalt Pavement (RAP). The use of Reclaimed Asphalt is one of the most economical and environmentally friendly methods of pavement construction. RAP is the term given to materials that have come from asphalt pavements that have to be removed. They are then crushed down to produce a high quality and well graded aggregates. There has been much research done to assess the use of this material. Mix Design When carrying out tests on the material design mixes similar to that currently in practise in Ireland were used. This was to give, as close as possible, a representation of the results of the performance fatigue of Irish pavements. To achieve this, a standard mix of 20mm binder course was used. For more comprehensive result varying amounts of RAP were added. Control samples were used to compare the results with and RAP was added at levels of 10, 20 and 30%. Samples needed to be taken to insure the material that would be produced was in accordance with the British standard BS 812: Part 103.1 (BSI 1985). It was necessary to calculate the surface area of the aggregate to find out if adjustments needed to be made to the amount of binder that was required a simple formula was used to provide this information (Shell Bitumen 1991): T= b/(100-b) x 1/Db x 1/SAF T= bitumen thickness (m) Db= density of bitumen (kg/m3) SAF= surface... ... middle of paper ... ...Deflection Test The previous test also produced results for the permanent deflection of the slab. As a result of the simulated weak foundation the initial deflection was quit sever when viewed to next to the deflection present in the later stages of the test. The results reported by this test showed that samples had deflected considerably more than those that included RAP and there was a direct link between an increase of RAD and a decrease in the level of deflection. The results of the above test have proven on several occasions that reclaimed asphalt pavement is a suitable source of material for the production of pavements. It has become so well accepted that previsions have been made in both the British and Irish Design Standards to incorporate information gathered on such materials. Information on RAP and other such recycled materials are present in Series 900.

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