Rubberasfalt in de wegenbouw Fedde Tolman Hollandsche Beton Groep - Civiel Netherlands Pavement Consultants bv

contents u pavements u asphalt u bitumen u modified bitumen u rubber modified binder

pavements u primary function: transfer forces from vehicle to earth u loads on pavements F traffic -mechanical -noise F weather -moisture induced softening of grain material -high temperature softening -cracking due to restrained shrinkage

u pavement performance - crack control - evenness - fixation of particles - skid resistance - visibility F noise

u applications - roads - industrial areas - airports - bridge decks - steel: structural - concrete: environmental protection - floors

Pavement structure

composition asphalt u mineral (type and gradation) u bitumen (pen) u additives u pores

Most important Dutch asphalt types

bitumen u Samenstelling –asfaltenen –maltenen –alifaten –aromaten u karakterisering –rheologisch (modulus en fasehoek) –empirisch (penetratie en verwekingspunt) –functioneel empirisch (breekpunt, verwekingspunt, mengviscositeit)

Polymer modifications

Inert and chemical modifications

Consistency - temperature

Force - ductility

Molecular distribution

Risks in modifications -compatibility bitumen and polymer problematic (mixing of bindertypes) -asphalt mixing and compaction higher risk of being problematic -mechanical improvement unclear -hot reuse in principle no problem -registration of application regarding demolition -quality control of procedure; tedious product control

Rubber in asphalt

rubber in pavements: panacea? –rubber modified binder in asphalt -stiffness, fatigue, stability (permanent deformation) -impact absorption and strength -damping of vibration -abrasion -noise -friction -reduced temperature sensitivity -durability (ageing, adhesion, friction)

Types of rubber applications u in asphalt - rubber granulate and filler in asphalt - blocks, tiles and slabs - joints u in binder - dissolved - emulsification - powder (5 – 7%) - tyre scrap (4 – 8 %)

u motives: - improvement of pavement - recycling / waste reduction (esp. of wasted tyres) u sustainability - emission - exposure - toxicity F environment

Effect rubber addition

Proefvakken A

Productie 18 juni (vakken 0 t/m 5) u aanleg ZOAB-proefvakken probleemloos u vak 1 met 4,5% rubberbitumen stolling van het bindmiddel: verpompbaarheid - bindmiddeltemperatuur verhoogd  viscositeit - pomp roerketel en installatie in serie  druk u vak 2 (5,5 %) geen problemen u vak 4 (4,5%) zelfde problemen als vak 1 u vak 5 (5,5%) geen problemen

conclusions u Technical –bitumen are the main binding part; polymers and rubbers are specific –mechanical properties may be improved but also worsened by rubber addition –quality control problematic –no final qualification

u Environmental –reuse tires –reduction noise –higher production temperatures u Health and safety –exposition to tire components –higher temperatures --> more emissions

perspectives u Rubber remains of interest for modifying binders and may become so as granulates u noise and reuse most important motives u vibration and impact may be of interest