PORTABLE SEISMIC PAVEMENT ANALYZER- PSPA 498-EXPERIMENTAL METHODS Professor: Daniel Kuchma Speaker: Sara Alzate INSTRUMENTATION PROJECT University of Illinois at Urbana-Champaign March 14 th 2007

OUTLINE Brief History about PSPA. PSPA Primary Uses. Methods of NDTE used in PSPA. Advantages and Disadvantages. Commercial References. Questions Session.

PSPA History Portable Version of the SPA, Seismic Pavement Analyzer. Developed by researchers at University of Texas, El Paso.(1995) Integrates sonic, ultrasonic, and resonant vibrations to nondestructive evaluation of pavements. Was primarily developed to analyze the upper pavement layer.

Brief PSPA History Courtesy of: Geomedia Research & Development. Receivers - Accelerometers Source- Electromagnetic Hammer

FUNCTION OF PSPA 1. Modulus calculations for the top layer. (USW- TRA) 2. Thickness of the top layer. (IE) 3. Depth to delaminated interfaces. (IE) Courtesy of: Cement Association of Canada.

NDE PRINCIPLES 1. TIME RECORD ANALYSIS: Uses one impact (source) and two accelerometers (receivers). The P-wave and the R-Wave are recognized and the time of the peak stored. The distance between accelerometers by the difference between the first and the second receiver is the velocity. From this, the Young Modulus can be found.

NDE PRINCIPLES 2. ULTRASONIC SURFACE WAVES: Stress waves are propagated through a solid or liquid media, its propagation depends on the mechanical properties (as density or modulus) of the excited media. The principle is shown below: V S = V R ( ) E = 2 (  V S 2 (1 + ) AnalySurfWaveandUltrSonicSurfWaveMethods.htm

NDE PRINCIPLES 3. IMPACT – ECHO A low frequency stress wave is generated by a short time impact. Waves are reflected back by internal interfaces or external boundaries. D =  C p /(2 f)

ADVANTAGES Time analysis record is rapid to perform and the data reduction is very simple. The USW are sensitive to properties of the top layer, is a fast test and gives specific results. Impact Echo can be used to determine the thickness of the top layer and is sensitive to flaws existence.

DISADVANTAGES The results of the TRA can be affected by the underlying layers and are very sensitive to the surface condition. Impact Echo needs high modulus magnitude differences between the first and the second layer. At least one core is needed for calibration in multiple layers. Applies only to pavements with thick top layer.

COMMERCIAL INFORMATION PSPA was developed by the University of Texas el Paso and its manufacture and commercialization is owned by Geomedia Research and Development. The principal clients of this technology are the DOT’s for bridge deck analysis and pavements QA/QC.

REFERENCES D.Yuan, S.Nazarian, D. Chen, M. MacDaniel. Use of Seismic methods in monitoring pavement deteiroration during accelerated pavement testing with TxMLS. M. Kruntcheva, A. Collop, N. Thom. Feasibility of Assesing Bond Condition of Asphalt Concrete layers with dynamic nondestructive testing. A. Davis, B. Hertlein, M. Lim, K. Michols. Impact-Echo and Impulse Response stress wave methods: Advantages and limitations for the evaluation of highway pavement concrete overlays.