The effect of salt and extreme temperatures on aggregates used in asphalt pavements

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1 The effect of salt and extreme temperatures on aggregates used in asphalt pavements Patricia Pérez Fortes (PhD student UCM-CEDEX) Madrid, Spain Researcher in formation in Geology Complutense University of Madrid (UCM) Faculty of Geology Department of Petrology and Geochemistry Geosciences Institute (IGEO) Petrophysics Laboratory Spanish Civil Engineering Research Agency (CEDEX) Geotechnical Laboratory Transports Laboratory 1/16 1

2 Researcher in formation in Geology NOWADAYS Individual Mobility of Researchers Programme between Spain, Norway, Iceland and Liechtenstein Pre-doctoral stay in Trondheim for 6months 2/16 MY THESIS PROJECT To study the quality and durability of road aggregates in areas where is common the use of salts in winter To apply portable and fast techniques of quality analysis complementary to the Standard Tests 3/16 2

3 WINTER MAINTENANCE: WHY DO WE USE SALTS ON ROADS? EFFECT OF ICE/SNOW IN ROADS: Reduction of surface adhesion Loss of control and collisions FREEZING-POINT DEPRESSANTS Chlorides (NaCl, MgCl 2 and CaCl 2 ) Abrasives (sands, ) Acetates (Kac, NaAc, CMA) Most common 4/16 WINTER MAINTENANCE IN SPAIN Main freezing-point depressant SALT (NaCl) USE OF SALT IN SPAIN 225,000t per year 25,633km of roads under winter maintenance 96% Preventive treatment Spread salt before snowfall/ice-formation IF NOT Image from Girona, Spain (2010) Image from Galicia, Spain (2010) A MESS! 5/16 3

SPAIN Average: 5-10 days of snow per year WHY ASPHALTS IN SPAIN ARE

4 EFFECTS OF THE USE OF SALTS IN ROADS IN SPAIN CRACKS LOSS OF MATERIAL Loss of security and driving comfort 6/16 SNOWFALL IN SPAIN Average: 5-10 days of snow per year WHY ASPHALTS IN SPAIN ARE DAMAGED BY SALTS?? Sources: AEMET, Spanish Environmental Service, IGN. 7/16 4

5 LOCATION OF MATERIALS STUDIED : Touro 8/16 MATERIALS EXPLOITED: Geological map of the Arinteiro unit (Gómez Barreiro, J., Wijbrans, J. R., Catiñeiras, P., Martínez Catalán, J. R., Arenas, R., Díaz García, F., Abati, J Ar/39Ar laserprobe dating of mylonitic fabrics in a polyorogenic terrane of NW. Iberia. Journal of the Geological Society, London, 163: 61 73) 9/16 5

6 WEATHER CONDITIONS Santiago de Compostela: Local towns (mountain conditions) Winter conditions Low T -3º C 6 days of snow per year Hr 80% Winter conditions Low T -5º C 26 days of snow per year Hr 80% 10/16 WEATHER CONDITIONS: WHAT HAPPENS IN SUMMER? Santiago de Compostela: Local towns (mountain conditions) Summer conditions High T 40º C Hr 80% Summer conditions High T 36º C Hr 80% 11/16 6

7 Precipitations (L/m2) Precipitation (L/m2) WEATHER CONDITIONS: 350,0 300,0 250,0 200,0 150,0 100,0 50,0 0,0 Precipitations in Santiago de Compostela, Spain (2012) Periods without precipitations Precipitation (L/m2) SUMMARY 5-25 days of snow per year Temperatures under O degrees High temperatures in summer Low precipitations 400,0 350,0 300,0 250,0 200,0 150,0 100,0 50,0 0,0 Precipitations in Arzua, Spain (2012) Periods without precipitations Precipitations (L/m2) Could be high T with salts a cause too of pavements damages in Spain? 12/16 LABORATORY WORK SIMULATION OF CLIMATOLOGICAL CONDITIONS IN WINTER AND SUMMER Freeze-thaw test Thermal shock test Natural Stone Aggregates Asphalt mixture 13/16 7

8 Force (N) LABORATORY WORK EFFECTS EVALUATION STANDARD TESTS (UNE-EN) Water absorption Uniaxial Compressive Strength Test Polished Stone Value Test (PSV) Los Angeles Abrasion Value Test (LA) Wheel Tracking Test OTHER TECHNIQUES Optical and Fluorescence Microscopy X-Ray Diffraction/ X-Ray Fluorescence Mercury porosimetry Micro-drilling resistance of an asphalt mixture TECHNIQUES FROM OTHER FIELDS Optical surface roughness tester MicroHardness Durometer Tester Micro-drilling Resistance Tester Depth (mm) 14/16 SOME CONCLUSIONS: AGGREGATES ARE MORE AFFECTED BY SALT EXPOSURE THAN ASPHALT Asphalt matrix Aggregate Image form Optical Microscopy Image form Fluorescence Microscopy 15/16 8

9 SOME CONCLUSIONS: THERMAL SHOCK TEST WITH SALT IS MORE AGGRESIVE THAN FREEZE-THAW TEST Aggregate surface Aggregate surface Freeze-thaw test Thermal shock test Image form Fluorescence Microscopy Image form Fluorescence Microscopy 16/16 THANKS! 9

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