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Article Concrete containing RAP for use in concrete pavement

Article Feasibility study of RAP aggregates in cement concrete pavements

Thanks Kundan Meshram for your help

Dear Saloua,

The failure in RAP concrete is associated with asphalt cohesion failure. That means, without removing the asphalt film, the ITZ cannot be strengthened. However, you may try the following

a) Inclusions of supplementary cementitious admixtures such as silica fume wouldn't have any significant effect on the strength properties of RAP concrete, however, higher Portland cement content can enhance the same.

b) If the RAP is highly oxidized by virtue of higher service life of pavement or stockpiling in open environment, the stiffened asphalt film would have better adhesion with the mortar matrix. (see: Laboratory investigation of RAP aggregates for dry lean concrete mixes)

c) Mechanical roughening of stiffened asphalt film may provide with patches of clean aggregate surface and thus chances of bonding between mortar and aggregates would increase. (See: An economical processing technique to improve RAP inclusive concrete properties. AND Feasibility study of RAP aggregates in cement concrete pavements).

Moreover, inclusions of supplementary cementitious admixtures in beneficiated RAP concrete would further enhance the strength and durability properties. (See: Effect of mineral admixtures on fresh, mechanical and durability properties of RAP inclusive concrete).

d) If you are planning to use fine RAP, milling of the same employing uncontrolled milling technique may provide you relatively well graded fine RAP and thus, the properties of PCC would be better as compared to the gap graded fine RAP inclusive PCC mixes. (see: Laboratory Investigation of Concrete PavementsContaining Fine RAP Aggregates).

Add fly Ash and superplasticizer.

Thank you Mr Tarek for your answer

Dear Saloua

The majour issue is the presense of asphalt cement which prevent the required adhesion. It is not recommended to use reclaimed asphalt concrete aggregates into concrete pavement, but it maybe used for Construction of a new asphalt concrete pavement.

Thanks Dr Saad Sarsam for your answer.