Non-Destructive Pavement Testing at IDOT LaDonna R. Rowden, P.E. Pavement Technology Engineer
Bureau of Materials and Physical Research Physical Research Section Bridge Investigations Unit Pavement Technology Unit Products Evaluation Unit Technical Services Unit Operations Sub-Unit Pavement Data Management Sub-Unit
Types of Testing Pavement Surface Distress and Riding Quality Skid Resistance (Pavement Friction) Falling Weight Deflectometer (FWD)
Pavement Surface Distress and Riding Quality
Pavement Surface Distress Six cameras record images from the roadway Three front-facing perspective One rear-facing Two pairs of down-facing (only one set collects at a time) Images collected at a rate of 3 to 1, downward to perspective
Pavement Riding Quality International Roughness Index Measurement relating how passengers perceive the roughness of the pavement. Pavement Profile analyzed using a quarter-car simulation. Collected in each wheelpath using lasers. Recorded in inches/mile (mm/km).
International Roughness Index (IRI) Subjective Ratings for All Countries RATING Smooth Medium Rough VALUE 0 to 190 191 to 320 Over 320
Pavement Riding Quality Rut Depth Permanent deformation of the pavement surface due to wheel loads. Collected through lasers in each wheelpath. Recorded in inches (mm).
Pavement Riding Quality RWG LWG LWG RWP CEN LWP Calculations: Left Rut Depth: LWP-(CEN+LWG)/2 Right Rut Depth: RWP-(CEN+RWG)/2 Center Rut Depth: (RWP+LWP)/2-CEN
Pavement Surface Distress and Riding Quality Information stored in a database. IDOT has 15 workstations for reviewing images and data. Select 5 predominant distresses. CRS value determined from distresses and ride quality data.
Pavement Inventory Interstates Tested Annually Non-Interstates Tested Biannually Even Years: 1 (Cook Co.), 4, 5, 8, 9 Odd Years: 1 (Collar Co.), 2, 3, 6, 7 Special Requests
SKID RESISTANCE (Pavement Friction) Slippery when wet Sharon Haasis Bureau of Materials & Physical Research
SKID TRAILER
FRICTION NUMBER (FN) Represents the frictional properties of the pavement. Used to evaluate skid resistance of the pavement relative to other pavements. Used to evaluate the change in skid resistance of the pavement with time.
FN t and FN s FN t represents treaded tire measurements. FN s represents smooth tire measurements. Treaded tire measures microtexture of pavement. Smooth tire measures macrotexture of pavement.
PAVEMENT PROPERTIES Microtexture Irregularities of aggregate surface Measured by Treaded Tire Macrotexture Drainage paths between aggregate particles Measured by Smooth Tire
ASTM E274 Standard Test Method for Skid Resistance of Paved Surfaces Using a Full-Scale Tire Test Speed of 40 mph Water sprayed under tire Brake applied Torque on axle recorded Friction Number calculated
TESTING CATEGORIES HA - wet weather accident locations. NC - new construction and pavement rehabilitation sites. RR - reruns of the new construction jobs. MS - Miscellaneous test requests (Unknown construction contract numbers and special request jobs).
INFLUENCES Surface Course Age Traffic Seasonal Changes Speed
REASONS FOR FRICTION TESTING Evaluate Mixture Performance Bituminous Mixture type determined by ADT level Mixture C: 0 5,000 Mixture D: 5,001 25,000 (4-lane) 5,001 60,000 (6-lane) Mixture E: 25,001 100,000 (4-lane) 60,001 100,000 (6-lane) Mixture F: > 100,000 PCC texture determined by speed limit Type A Finish: Type A or B Finish: > 40 mph 40 mph
CATEGORICAL RATING GUIDELINES FN t < 30 or Friction may be a factor contributing to wet weather accidents FN s < 15
QUESTIONS? Contact: Sharon Haasis, Research Engineer Bureau of Materials & Physical Research 217-782-0551 haasissl@nt.dot.state.il.us Or LaDonna Rowden Pavement Technology Engineer Bureau of Materials & Physical Research 217-782-8582 rowdenlr@nt.dot.state.il.us
Falling Weight Deflectometer (FWD) Testing at IDOT Charles J. Wienrank, P.E. Pavement Analysis Engineer
What is an FWD? Impulse loading device used for structural evaluation of pavements. Load is applied to pavement that simulates truck or aircraft wheel loads. Resulting deflections are measured using a series of velocity transducers. Deflection data used to analyze pavement structure.
Deflection Basin
Advantages of FWD Accurately models a moving wheel load. Does not damage pavement. Testing can be done rapidly and at a lower cost than destructive testing. 50 to 60 tests done per hour. Less disruptive to traffic than destructive testing.
Flexible Pavements Determine structural adequacy of pavement. Determine uniformity of support along a project and identify weak areas. Estimate subgrade and pavement layer elastic moduli values. Determine overlay thickness requirements. Develop cost-effective maintenance and rehabilitation alternatives.
0+00 6+00 12+00 18+00 24+00 30+00 36+00 42+00 48+00 54+00 60+00 66+00 Sample Deflection Profile 40 35 30 25 20 15 10 5 0 Test Location Deflection (mils)
Rigid Pavements Locate areas of poor support beneath jointed concrete pavements. Determine load transfer efficiency across joints and cracks. Estimate subgrade and pavement layer elastic moduli values. Develop cost-effective maintenance and rehabilitation alternatives.
IDOT s FWD Program Project Level Testing is 95% 3 Main Areas Local Agency Testing Monitoring of Experimental Sections Seasonal Variation Program
Local Agency Testing Counties, Cities, Townships, Airports 20 to 25 Projects / Year Estimate Remaining Life and Overlay Thickness Requirements
Monitoring of Experimental Sections 2/3 of Testing Dowel Bar Experiment ATREL Test Sections Rubblizing Projects Open-Graded Drainage Layers Mechanistic Designs Miscellaneous
Seasonal Variation Program Monthly testing performed at 4 locations in the Springfield area. Measured deflections can vary greatly depending on temperature and moisture conditions. Deflection data collected during noncritical period is adjusted to reflect worst-case scenario.
Questions? LaDonna Rowden Sharon Haasis (217) 782-8582 (217) 782-0551 rowdenlr@nt.dot.state.il.us haasissl@nt.dot.state.il.us Charles Wienrank (217) 782-0570 wienrankcj@nt.dot.state.il.us