ROAD AND RAILWAY CONSTRUCTION

Transcription

1 MSC COURSE 2016/2017 AUTUMN SEMESTER ROAD AND RAILWAY CONSTRUCTION ASPHALT MIXTURES SZÉCHENYI ISTVÁN UNIVERSITY Dr. Péter FÜLEKI assistant professor

2 6th lecture s theme Asphalt mixture types Production Types Tests 6th Lecture

3 Asphalt mixture is a mix of bitumen and aggregates. Because binder (bitumen) behaves as viscoelastic material, asphalt mixture has viscoelastic properties. During summer time the viscous properties will be relevant. During winter time asphalt mix will be more stiff, but elastic properties stay dominant. The Hungarian asphalt design temperature range is between -25 C and +60 C.

4 can be produced: by mixing, by spraying or scattering (thin, on site produced asphalt layers). Depending on production s temperature of technology: cold method (CMA), warm method (WMA), hot method (HMA), hot mixing-cooking (MA).

5 With mixing method produced asphalt mixtures can be: 3 phases system (bitumen, aggregate, air) 2 phases system (bitumen, aggregate, without air) (Mastic asphalts - MA)

6 Cold methods: Sprayed or scattered surface coat with bitumen emulsion binders. Mixed surface coat (Slurry seal) (self-setting, 1cm thick, with modified bitumen emulsion as binder). Warm methods: Soft asphalts for pavements with low traffic density (produced with soft bitumens). with bitumen emulsion (not surface coat!) for filling potholes and using during maintenance.

7 Hot methods: asphalt mixtures with 3 phases (bit, agg, air), production between C, Mixing-cooking with 2 phases (bit, agg), production between C (mastic asphalt). Special coating mixtures (SAM Stress Absorbing Membrane, SAMI Stress Absorbing Membrane Interlayer).

8 Mass % Air void content Volume % Aggregate 100% volume

9 System of European harmonized standardisation of hot mix asphalts Standards of asphalt products EN National specifications UME, e-ut Testing methods of harmonized components Basic equipments and calibration Supportive standards Quality standards Standards of raw materials Harmonized standard: Fulfil the fundamental requirements, prepared according mandate, worked out by CEN, accepted by member states, accepted by EU experts, published in official EU bulletin

10 types Asphalt types according EN standards: Asphalt concrete (AC) Beton bitumineux trés mince (BBTM) Soft asphalt (SA) Hot rolled asphalt (HRA) Stone mastic asphalt (SMA) Mastic asphalt (MA) Porous asphalt (PA) Reclaimed asphalt (RA)

11 Asphalt laying methods Hot ( C) (B) Warm ( C) (B) Half warm ( C) (AB) Cold (environmental temperature) (BE, AB) B bitumen AB with gasoline attenuated bitumen BE bitumen emulsion

12 Types of binders Paving grade bitumen Modified bitumen Bitumen emulsion Attenuated bitumen Additional method of binder Mixing-cooking (MA) Mixing Spraying (coating)

13 Phase system 2 phase (bitumen, aggregate) (MA) 3 phase (bitumen, aggregate, air) Compaction methods Without compaction With compaction (vibrating, smoothing)

14 Partical size distribution (grading) All-in aggregate (AC) Fractional (SMA) All-in aggregate elliptic (HRA) Compactness (compaction degree) Compact-closed (air void content 2-4%) Compact-opened (avc 20-22%) After compacting (very low traffic density)

15 Applying in the pavement: Surface course, Binder course, Upper base layer, Lower base layer.

16 Fuller curve for grading of aggregate If we deviate from the original Fuller curve then air void content will be too high -> higher frost risk, smaller resistance of fatigue, air void content will be too low -> slippery pavement, plastic deformation.

17 Asphalt concrete: Air void content 3,5-5,5 v/v%, Higher air void content result in smaller fatigue lifetime, frost risk, (but good surface texture and skid resistance) Lower air void content result in good fatigue lifetime (but lower skid resistance, and worse resistance against deformation) Hot rolled asphalt: Air content higher Scattering on asphalt layer after laying

18 Stone mastic asphalt: Surface course of highways with modified bitumen Angular aggregates Mastic asphalt: Most expensive, longest lifetime Air void content 0 v/v% Highest bitumen content -> slippery surface -> must be more rough Isolation layer for bridges Pavement of pathway or sidewalk

19 Porous asphalt: Drainasphalt (air void content v/v%) Water can seep through the layer Noise reduction Lower fatigue lifetime Air void can be filled in with pollution No frost risk BBTM: Up to 30 mm course thickness Produced with hard modified bitumen

20 BBTM: Up to 30 mm course thickness Produced with hard modified bitumen Soft asphalt: So called Finnish asphalt Produced with soft bitumen (penetration )

21 Thank you for your attention!