Asphalt concrete mixtures with high RA content s:, design performance a, LNEC, 25 March 2010 Maria de Lurdes Antunes, LNEC Fátima Batista, LNEC Luís Picado Santos, FCT UC António Baptista, IPV Paulo Pereira, UM Jorge Pais, UM Road
Background: Hot mix asphalt recycling in Portugal >1999 - First known applications of RA in the production of hot mix asphalt concrete in Portugal >Growing interest in asphalt recycling since then >2006 - LNEC published E 472 (Guide for the production of recycled hot mix asphalt); reviewed 2009 >2009 Review of E 472 Road s:, design performance
Background: Hot mix asphalt recycling in Portugal >2009 New specifications for highway works (Estradas de Portugal) include provisions for use of RA in Hot Mix Asphalt Concrete (HMAC) >Many CE marked HMAC in Portugal include up to 20% of RA >Higher percentages of RA are used in specific cases Road s:, design performance
Objectives >To discuss the main issues associated with the used of high RA contents in HMAC >To present research results concerning mix design performance of HMAC with high RA Project REPARE (LNEC + FCT UC + UM) Road s:, design performance
Main issues associated with high RA content in HMAC >Technology No longer an issue >Mix design >Grading of aggregate mixture >Binder properties >Variability Too many fines Properties of final blend? Road s:, design performance
Control of variability in HMAC with RA At the asphalt plant >Separation of RA into 2 or more stockpiles According to RA particle size More flexibility to adjust aggregate gradation Better consistency of binder content (finer particles will have higher content) >Blending the materials to get a uniform stockpile Road s:, design performance
Control of variability in HMAC with RA At the lab >Test several samples for aggregate gradation binder content properties Reblend the materials if variability is too high >Use representative samples of RA for mix design Blend diferent samples to get a representative sample Road s:, design performance
Early applications of HMAC using RA Rehabilitation of EN 105 road pavement (1999) Road s:, design performance
Rehabilitation of EN 105 Mix composition (binder course) 40 % Reclaimed Asphalt 15 % Aggregate 14/20 10 % Aggregate 10/14 10 % Aggregate 6/10 23 % Fine aggregate 0/6 2 % Aded filler Virgin bitumen: pen 35/50 Final binder content:5,4 % Road s:, design performance
Rehabilitation of EN 105 Grading of aggregate mixture EN 105 Hot mix asphalt concrete with 40% RA % de material pas ssado 100 90 80 70 60 50 40 30 20 10 0 0,01 0,1 1 10 100 abertura dos peneiros (mm) fuso C.E. da Obra Mistura de agregados composta Agregados do material fresado Road s:, design performance
Rehabilitation of EN 105 Binder properti ies Road s:, design performance Penetration, 0,1 mm Softening point, ºC 100 10 1 100 10 1 Recovered binder (from RA) Final blend PEN 35/50 Virgin bitumen t AB (ºC) 50/58 0 20 40 60 80 100 Final blend 0 20 40 60 80 100 Content of virgin bitumen in the final blend
Rehabilitation of EN 105 Stiffness fatigue Road 4 PB (f=10hz; t = 22ºC) FWD tests E > 5000 Mpa (@ ~20ºC) 10000 Stiffness: E 4000 MPa Field testing Lab testing Road s:, design performance Extensão (µm/m) 1000 100 10 1 Vigas de mistura reciclada em central Mistura convencional, tipo macadame betuminoso 100 1.000 10.000 100.000 1.000.000 Número de aplicações de carga (ESH, LNEC)
Rehabilitation of EN 105 Resistance to permanent deformation Wheel tracking tests (t = 60ºC) 8,00 Deformação (mm) 7,00 6,00 5,00 4,00 3,00 2,00 L1 L2 V 105-120 (x10-3 mm/min) 18 17 1,00 (WT, LNEC) 0,00 0 10 20 30 40 50 60 70 80 90 100 110 120 Tempo (minutos) Road s:, design performance
Rehabilitation of EN 105 Still in good shape after 10 years! Road s:, design performance
HMAC with high RA content Laboratory investigation >Laboratory mixtures produced with the following materials: RA milled from motorway A1 (Pombal / Condeixa); 5,1% binder content (pen 14 x 0,1mm). Virgin binder: o Pen 35/50 o Pen 50/70 o Pen 70/100 Virgin aggregates: limestone >Follow-up of previous studies concerning mixtures with up to 40% RA (António Baptista, 2006) Road s:, design performance
HMAC with 60-70% RA Aggregate grading Road 100 90 Fuso-l1 % passin ng 80 70 60 50 40 30 Fuso-l2 70% Mat.Fres. 60% Mat.Fres. No aded filler Only 15/25 mm virgin aggregates 20 10 0 0,01 0,1 1 10 100 sieve size (mm) Road s:, design performance
Marshall mix design for HMAC (1/3) 70% RA; pen 50/70 virgin binder Density 2425 Void content 13,0 2400 11,0 2375 9,0 ρb (kg/m3) 2350 Vv (%) 7,0 2325 5,0 2300 3,0 2275 1,0 3,5 4,5 5,5 6,5 3,5 4,0 4,5 5,0 5,5 6,0 6,5 Pb (%) Pb (%) Road s:, design performance
Marshall mix design for HMAC (2/3) 70% RA; pen 50/70 virgin binder Marshall stability Flow 33,5 5,0 28,5 4,5 23,5 4,0 S (kn) 18,5 F (mm) 3,5 13,5 3,0 8,5 2,5 3,5 3,5 4,0 4,5 5,0 5,5 6,0 6,5 Pb (%) 2,0 3,5 4,0 4,5 5,0 5,5 6,0 6,5 Pb (%) Road s:, design performance
Marshall mix design for HMAC (3/3) 70% RA; pen 50/70 virgin binder Voids in Mineral Aggregate 18,0 17,0 16,0 VMA (%) 15,0 14,0 13,0 12,0 3,5 4,0 4,5 5,0 5,5 6,0 6,5 Pb (%) Selected binder content: 5,0 % (total) Road s:, design performance
HMAC with 70% RA; 50/70 pen virgin binder Marshall characteristics water sensitivity Bulk Void Marshall Marshall VMA ITSR Density content Stability Flow (Mg/m 3 ) (%) (kn) (mm) (%) (%) Results 2,395 2,9 25,4 2,8 13,4 100 EP specification - 3-6 7,5-15 2-4 14 - Road s:, design performance
HMAC with 70% RA; 50/70 pen virgin binder Wheel tracking test Road s:, design performance
HMAC with 70% RA; 50/70 pen virgin binder Stiffness Stiffness (M MPa) 12000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 Road s:, design performance 0 f=10hz f=5hz f=2hz f=1hz f=0.5hz f=0.2hz f=0.1hz 0 10 20 30 40 50 Temperature (ºC)
HMAC with 70% RA; 50/70 pen virgin binder Stiffness 100,0 Phase angl le (º) 10,0 f=0.1hz f=0.2hz f=0.5hz f=1hz f=2hz f=5hz f=10hz 1,0 0 10 20 30 40 50 Temperature (ºC) Road s:, design performance
HMAC with 70% RA; 50/70 pen virgin binder Fatigue (25ºC; 10 Hz) 10000 Virgin binder: pen 50/70 Tensile stra ain (x 10-6) 1000 100 1E+02 1E+03 1E+04 70% 1E+05 1E+06 1E+07 Number of load applications Road s:, design performance
HMAC with high RA content Laboratory mixtures RA Virgin binder (pen grade) Final binder content 0 35/50 - - 4,2% 20 % 35/50 50/70-4,3% 30 % 35/50 50/70 70/100 4,4% 40 % 35/50 50/70 70/100 4,7% 70 % - 50/70 70/100 5,0% Road s:, design performance
Fatigue of laboratory mixtures with RA (4PB @ 25ºC; 10 Hz) Virgin binder: pen 50/70 10000 10000 Tensile strain (x 10-6 6) 1000 1000 30% 40% 70% 100 100 1E+02 1E+03 1E+04 1E+05 1E+06 1E+07 Number of load applications Road s:, design performance
Fatigue of laboratory mixtures with RA (4PB @ 25ºC; 10 Hz) 30% RA 10000 10000 Tensile strain (x 10- -6) 1000 1000 B35/50 B50/70 B70/100 100 100 1E+02 1E+03 1E+04 1E+05 1E+06 1E+07 Number of load applications Road s:, design performance
Fatigue of laboratory mixtures with RA (4PB @ 25ºC; 10 Hz) 40% RA 10000 10000 Tensile strain (x 10-6 6) 1000 1000 B35/50 B50/70 B70/100 100 100 1E+02 1E+03 1E+04 1E+05 1E+06 1E+07 Number of load applications Road s:, design performance
Final remarks >Using high RA content in HMAC Need extra care to control variability Dificult to comply with stard (empirical) specifications You can still achieve good performance! >Future work Assess ageing of mixtures with high RA Move to performance specifications Road s:, design performance