What is the purpose of paving bituminous surfacing over concrete
structures?
I believe asphalt overlay on concrete can help in following way:
1. To reduce moisture damage in subgrade
2. To improve adhesion between the vehicle tire and the road surface (note that concrete surface has lower adhesion than asphalt surface)
3. To reduce noise
4. To reduce deicing salt penetration and thereby to reduce to corrosion in rebar
Hope it helps Amjad!
Cheers
Kamal
The use of bituminous surfacing over concrete structures (e.g. existing
concrete roads) is widespread to improve the skid-resistance and the
general appearance of roads on one hand, and to avoid the pre-mature
failure of concrete surface by frost spalling in cold countries on the other
hand.
In designing the bituminous surfacing over concrete, there are several
areas to which engineers should pay attention. Firstly, the laying of thin
bituminous material over the joints or existing cracks of concrete structure
would lead to reflective cracking because the thermal movement of
concrete induces swift formation of cracks in bituminous surfacing. Past
research demonstrated that with the adoption of minimum thickness of
100mm bituminous surfacing the occurrence of reflective cracks would be
delayed when compared with the use of thinner surfacing. Secondly,
sufficient adhesion between concrete and bituminous surfacing has to be
achieved. Therefore, it is recommended to apply a layer of tack coat on the
concrete surface to promote bonding
Also if a concrete pavement is 400 mm thick and a heavier vehicle (eg. a new aircraft) requires it to be 500 mm thick, an asphalt overlay can provide the difference. A rule of thumb is 2mm of asphalt is equivalent to 1mm of concrete for these designs.
Cheers, Greg
To improve concrete's impermeability property. Therefore it may reduce the risk of chemical ingress and water penetration that may harm the steel reinforcement inside the concrete and eventually weaken the concrete structure.
To seal the concrete against the elements, to increase skid resistance value and reduce noise
I believe asphalt overlay on concrete can help in following way:
1. To reduce moisture damage in subgrade
2. To improve adhesion between the vehicle tire and the road surface (note that concrete surface has lower adhesion than asphalt surface)
3. To reduce noise
4. To reduce deicing salt penetration and thereby to reduce to corrosion in rebar
Hope it helps Amjad!
Cheers
Kamal
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