Experimental investigation on fibre-reinforced cement-treated materials using reclaimed asphalt

摘要

Cement treated materials (CTMs) are used as base or subbase courses for heavy-traffic highway. CTMs are characterised by high strength and stiffness ensuring a good support for the upper bituminous layers and by a uniform stress distribution on the lower layers. However, high stiffness of CTM can be self-defeating when the brittle behaviour becomes critical. In this case, CTM become typically prone to shrinkage cracking, which can lead to premature failure of the overall pavement. The use of polymer fibres, such as polypropylene fibres (PFs), can avoid the CTM weakening due to shrinkage phenomenon and it can prevent crack propagation with remarkable benefits in terms of service life of the road pavement. CTM were originally produced using natural or crushed aggregates but, currently, also recycled aggregates, such as reclaimed asphalt (RA), have been more and more used to preserve natural resources and to reduce the disposal of materials coming from the demolition of civil constructions. Although recycled aggregates could affect CTM mechanical characteristics, an accurate mix design and material selection allow appreciable performance to be reached. This paper is a part of an overall research project and it investigates the influence of PF dosage and RA content on CTM properties. In particular, 3-point bending tests and ultrasonic pulse velocity tests were carried out on CTM employing a combination of different PF dosages and RA contents.