Cracking in Costa Rica. Ing. Luis Guillermo Loria-Salazar, Ph.D.

Transcription

1 Workshop: New approaches to address pavement failure more realis.cally in asphal.c pavement design methods Recent Developments in Accelerated Pavement Tes5ng (APT) as a Pavement Design Tool for Cracking and Reflec.ve Cracking in Costa Rica Ing. Luis Guillermo Loria-Salazar, Ph.D. Paper N : xxxxx COSTA RICA - Located in Central America km 2 (Brasil: km 2 ) - 5,000,000 people ( immigrants) - No army since million of tourists a year. - A strong democracy since A very happy country!!!

2 UNIVERSITY OF COSTA RICA Transporta5on Infrastructure Program -LanammeUCR 90 Professionals Civil, Chemical and Mechanical engineers Physic Chemist Surveyors Geographer, geologist 30 Technicians - Funds: 8114 LAWà 1% Fuel Tax DUTIES: - Audi.ng labs/projects, evalua.on of na.onal roads, research, na.onal specs, technologhy transfer, local governments aaen.on 11 Ph. D. 4 Pavements 2 Hydraulics/Hydrologhy 2 Geotechnical 2 Structures/Bridges 1 Geology 12 M.Sc. 50 students/assitants

3 Research Areas/Scales NANO FULL SCALE MICRO MACRO Fa5gue/Reflec5ng cracking Factors to study the asphalt mix behavior in laboratory: Loading type Temperature Res.ng.mes Material proper.es Ageing 6

4 ME Approach Stress Strain Controled Tests Fa.gue life measured in field (APT) Distress/ Transfer Func.ons 7 Notched Semicircular Bending Fa.gue Test UGR test AMPT Overlay Test Tensile Stregth Test Fa.gue Tests Fenix Test Indirect Tensile Test Flexural Fa.gue Test 8

5 Stress or Strain controled? (Tangella et al. 1990) 5 Failure Criterion Fa5gue Tests Approaches: Phenomenological or empirical Energy Fracture Mechanics (Paris Law) 10

6 Phenomenological Approach Laboratory costarican mixtures: Beam Flexural Tests from 2004 to 2013 (617 raw data) Based on laboratory results, they need to be calibrated with data field!!! (HVS) (Vargas-Nordbeck et. al, 2013): 11 Acelerated Pavement Tests Response sources for many years It can be grouped in four categories Circular Circuit Linear fixed Linear movable Profilometer AASHO Road Test, Illinois

7 Circular 13 Circuit 11

8 Linear Fixed 12 Linear Movable 13

9 PaveLab LanammeUCR Since 2013 in Costa Rica 14 Tests specifica5ons 20,000 loads in two direc5ons per day Load speed: 10 km/hr Loads applied: 40, 60, 70, 80 kn Type of 5re: Dual 11R22-5 Wandering: 100 mm Dry condi5ons 23/7 15

10 Test Section m 30 s,c e n ick 40 T h 50 AC1 AC2 AC3 AC4 HMA HMA HMA HMA CTB GB GB CTB SB SB SB SB s,in e n ick T h Real field pavament Phase I Experiment Sifón-La Abundancia Project 20/Nbr tot.

11 Instrumenta5on Soil Pressure Transducers Mul.-Depth Deflectometer (MDD) Road Surface Deflectometer (RSD) Thermocouples Asphalt strain gauges Moisture sensors Cracking Ac.vity Meter 21/Nbr tot. Instrumenta5on 30 cm 60 cm 90 cm MDD Thermocouple MDD Sec.on Length = 6.0 m HMA GB/CTB Subbase Subgrade 17

12 59 millons ESALs applied Test ESALS 001 AC AC AC AC Transducers for deforma5on 004AC in 500 s tra ro ic 400 M MESALS 004AC3 40 kn Cracking Longitudinal Transverse 19

13 Fa5gue cracking 004AC3 20 Phenomenological or empirical analysis N k2 k2 = k ε N = k σ Where: N: Number of load cycles to fa.gue failure ε o σ: Applied tensile strain or stress (mm/mm) k i : Laboratory determined material constants Disadvantages: There is not a unique rela@onship High variability Fa@gue limit

14 Phenomenological Approach Beam Flexural Test on the mixture Plant: Laboratory: Field tests (HVS) (Leiva-Villacorta et. al, Con5nuum damage Con.nuum damage mechanics considers a damaged body with some s.ffness as an undamaged body with a reduced s.ffness, and the rela.onship between damage and effec.ve s.ffness must be characterized C - ΔModulus S Damage Internal State Variable 22

15 MDD Backcalcula5on of modulus 001AC M1 M2 M3 C a P M s, 1000 lu d u o M d 100 te la c a lu 10 a c k B Repetitions E SR σ d C MPa = 0.1 Average n = -0.4 n 700 Deflection Equality m, m500 n c tio 400 e fle 300 y = x D d R² = a te 100 E stim Measured Deflection, mm-3 40 kn CR-ME 23 Phenomenological Approach + Con5nuum Damage Beam Flexural Test on the mixture: Damage model Plant: Laboratory: Field tests (HVS) (Leiva-Villacorta et. al,

16 Phenomenological Approach + Con5nuum Damage Field tests (HVS): Damage model (damage level = 50%) Field tests (HVS) (Leiva-Villacorta et. al, 2015 Fa.gue damage models developed using plant and lab produced mix tended to underes.mate the observed APT damage by an average of 59% and 28% respec.vely 25 Energy Approach Dissipated energy is defined as the damping of energy or the energy loss per load cycle in any repeated or dynamic test (Van Dijk, 1975; Van Dijk and Visser, 1977; SHRP, 1995). 26

17 Energy Approach!"##"$%&'( '*'+,- $'+.-./' = 1 3 " 4 " #'*5 " Where: ε i : Strain amplitude at load cycle i σ i : Mix s.ffness at load cycle i φ i: Phase shir between stress and strain at load cycle 27 Energy Approach!"#$ % = "# % "# ( "# % (( %)!"#$%#& (#"&% = * / /100 Where: RDEC a : ra.o of dissipated energy change DE a y DE b : dissipated energy of a and b repeated load N f50 : fa.gue life at 50% s.ffness reduc.on point 28

18 Energy Approach Laboratory costarican mixtures: Beam Flexural Tests from 2004 to 2013 (617 raw data) (Vargas-Nordbeck et. al, 2013) 29 Energy Approach Laboratory costarican mixtures: Addi.onal models: (Vargas-Nordbeck et. al,

19 Energy Approach Pavement design: Improved fa.gue models: Based on laboratory results, they need to be calibrated with data from APT!!! (HVS) (Vargas-Nordbeck et. al, Fracture Mechanics Approach Reflec5ve Cracking 38

20 Fracture Mechanics Approach Log 32 Fracture Mechanics Approach Cores extracted from a overlay rehabilitated pavement using geotex.les: 1.E+01 y = 3592.x R² = Δc/ΔN 1.E+00 1.E-01 1.E-02 1.E-02 1.E-01 1.E+00 ΔG, J 33

21 Cohesive model Introduced by Dugdale and Barenblaa Suppose stress-displacement behavior in damage zone as a property of the material Used for studying the fracture in various materials, such as metals, polymers, ceramics, and geomaterials. 34 (a) Crack growth (b) Zone idealized as zone of strain sorening (c) Zone idealized by closure trac.ons (Anderson, 2005) 35

22 Bilinear trac5on-separa5on law Load, kn Stress Adhesive Bond Stregth Energy dissipa.on Prior to damage ini.a.on Displacement, mm Damage evolu.on Crack propaga.on 36 Overlay Tester Simula5on CZM elements Displacement (a) Reac.ons (b) Von Mises 37

23 Conclusions Fa.gue and reflec.ve cracking are Complex phenomena Required mul.-scale analysis to understand tand to model them Lab tes.ng APT tes.ng Field evalua.on Modeling 45/Nbr tot. Conclusions Fa.gue models developed for lab and calibrated for APT condi.ons Phenomenological approach Phenomenological approach + Con.nuum damage Energy Approach Reflec.ve cracking models under development Overlay tester Bilinear trac.on-separa.on law OT FEM simula.on APT test on queue 46/Nbr tot.

24 Comming soon 76 papers Interna.onal and na.onal par.cipants 13 themes hmp:// 38 Muchas gracias! hmp:// 48