NON DESTRUCTIVE
PAVEMENT EVALUATION
TECHNIQUES
Bassam E. Touma, Ph.D.
Touma Engineering – Engineering & Research Int’l

GOALS : SAFETY and CONFORT

GOOD MAINTENANCE & MANAGEMENT
PROGRAMS

REQUIRED PERIODIC INPUT:
1.
SURFACE CONDITION (FUNCTIONALITY)
STRUCTURAL INTEGRITY
2.

REQUIRE VARIOUS DATA COLLECTION
MEANS & DEVICES.
EVALUATION OF SURFACE CONDITION

EXISTING SURFACE DISTRESSES (MANUAL / VIDEO)

DEFLECTION MEASUREMENTS (STRUCTURAL
INTEGRITY)

RIDEABILITY OF THE PAVEMENT (i.e. ROUGHNESS)

RESISTANCE TO SKIDDING & HYDROPLPANNING
SURVEY OF SURFACE DISTRESSES
•
COMPUTE THE PAVEMENT CONDITION INDEX (PCI)
•
VISUAL SURVEY:
•
VIDEO LOGGING
1. ACCURATE IDENTIFICATION & MEASUREMENT OF
DISTRESSES
2. RELATIVELY SLOW
1. REQUIRES EXPENSIVE & SOPHISTICATED EQUIPMENT
2. DATA COLLECTION AY 40-60 KM/Hr
PAVEMENT CONDITION SURVEY

DIVIDE THE SURVEY AREA INTO SAMPLE UNITS

RECORD THE VISIBLE SURFACE DISTRESSES


DETERMINE THE SEVERITY OF EACH DISTRESS AND
THE PENALTY ASSOCIATED WITH IT.
CALCULATE THE S.U. AS WELL AS THE FEATURE’S
PAVEMENT CONDITION INDX (PCI)
VIDEO PAVEMENT CONDITION SURVEY
NON DESTRUCTIVE SURFACE DEFLECTION
MEASUREMENTS


BENKELMEN BEAM
1.
2.
3.
NON REPRESENTATIVE OF DYNAMIC LOADS
SINGLE READING MEASUREMENT
VERY SLOW
FALLING WEIGHT DEFLECTOMETER - FWD

FALLING WEIGHT DEFLECTOMETER
1.
2.
3.
4.

SIMULATES DYNAMIC TRAFFIC LOADS
UP TO 9 SENSORS MAY BE UTILIZED
FAST & REPEATABLE MEASUREMENTS
ASTM STANDARD
USE THE DATA TO DETERMINE:
1.
2.
3.
4.
5.
STRUCTURAL UNIFORMITY
MODULI VALUES FOR EACH LAYER
OVERLAY THICKNESS
LIMITING TRAFFIC LOADS
RESIDUAL SERVICE LIFE
BACKCALCULATION OF MODULI VALUES
 USE COMPUTER MODELS TO MATCH FIELD
DEFLECTIONS
 CALCULATE PAVEMENT LAYERS STRENGTH
 LOCATE WEAK AREAS OR OVERALL
EVALUATION
 DETERMINE SERVICE LIFE VS EXPECTED
TRAFFIC
SURFACE ROUGHNESS

ESPECIALLY IMPORTANT FOR THE EVALUATION OF PRIMARY
PAVEMENTS

AN IMPORTANT INDICATOR OF RIDING QUALITY & SAFETY

AFFECTED BY:
1. TRAFFIC LOADING (traffic loads / intensity)
2. ENVIRONMENTAL EFFECTS (heat, cold, wind, …)
3. CONSTRUCTION MATERIALS (concrete, asphalt, mixes…)
4. BUILT-IN CONSTRUCTION IRREGULARITIES (joints, cuts...)

QUALITATIVE vs QUANTITATIVE
RIDING INDICES ARE FOUND BY
USING PROFILE MEASURING DEVICES
1.
PRESENT SERVICEABILTY RATING (PSR = 0 – 5)

RATING PANEL (10-20 PEOPLE)

SUBJECTIVE RATING

MAY BE RELATED TO (IRI) THROUGH A TRANSFER FUNCTION
2.
INTERNATIONAL ROUGHNESS INDEX (IRI, m/Km):

ADOPTED FOR THE PURPOSE OF STANDARDIZING THE DATA EXCHANGE

CAR MOUNTED ROADMETER (RTRRMS) + OTHER SURFACE CONTACT

CAR MOUNTED – NON CONTACT DEVICES
RESPONSE TYPE ROUGHNESS
MEASURING SYSTEMS (RTRMS)



INSTALLS IN A MOVING VEHICLE OR TRAILER
MEASURES THE VERTICAL MOVEMENT OF THE REAR AXLE RELATIVE TO
VEHICLE FRAME
INDEX IS THE SUM OF SUSPENSION DEFLECTIONS OVER THE DISTANCE
TRAVELED

INDICES ARE VEHICLE DEPENDENT & NON REPEATABLE

O.K. IF CALIBRATED WITH A REPEATABLE INDEX

EACH SITE MUST BE TESTED SEVERAL TIMES AND THE RESULTS AVERAGED

REQUIRES PERIODIC CALIBRATION AND VERIFICATION
MANUALLY OPERATED CONTACT DEVICES

SLOW
REQUIRE LANE CLOSURE

NON REPEATABLE
Rotating Cylinder
with a Graduated
Sheet of Paper
Road Surface
Wheel Connected to a Free
Moving Rod and Needle Pen
NON-CONTACT MODELS




THE MATHEMATICAL MODEL SIMULATES A QUARTER CAR
SYSTEM (QCS), THUS, REPEATABLE
COMPUTED AS THE CUMULATIVE MOVEMENT OF THE QCS
SUSPESION DIVIDED BY THE TRAVELED DISTANCE
MAY BE RELATED TO MEASUREMENTS OBTAINED FROM
(RTRMS) DEVICES
MAY BE OPERATED AT HIGHWAY SPEEDS
ROUGHNESS MEASURING EQUIPMENT
EQUIPMENT / TECHNIQUE
COMPLEXITY
ROD AND LEVEL
SIMPLEST
DIPSTICK PROFILER
SIMPLEST
PROFILOGRAPHS
SIMPLE
RTRRMS
COMPLEX
AUTOMATED PROFILING
DEVICES
MORE COMPLEX
SKID RESITANCE EVALUATION
DEFINED AS THE FORCE THAT RESISTS SLIDING WHEN THE
TIRES ARE NOT ROTATING.
AFFECTED BY MANY FACTORS
1.
PAVEMENT SURFACE TYPE AND TEXTURE
2.
TIRE PRESSURE AND TREADS
3.
PRESENCE OF WATER
4.
SPEED AND LOAD OF VEHICLE
5.
TEMPERATURE
DETERIORATES WITH TIME & EXPOSURE TO TRAFFIC
SHOULD BE MEASURED PERIODICALLY ESPECIALLY WITH HEAVY
TRAFFIC
MUST COUPLE VISUAL AND MECHANICAL SURVEYS
LOCKED WHEEL MODE
• LOCK THE WHEEL AND APPLY WATER IN FRONT OF IT
• REQUIRES A STANDARD TIRE (ASTM E1551)
• RESULTS IN A SKID NUMBER (SN = % FRICTION FACTOR)
SLIP MODE
•
•
•
•
STRAIGHT MOVING VEH. SLIP INCREASES UNTIL 100%
F.FACTOR INCREASES TO A MAXIMUM AT “CRITICAL SLIP”
CRITICAL SLIP = f (TEXTURE, TEMPERATURE)
IT INDICATES THAT MAX. FRICTION OCCURS AT 10-15%
SLIP & NOT WHEN THE WHEELS ARE LOCKED (e.g. ABS)
THANK YOU
GROUND PENETRATING RADAR