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EMERGING TRENDS IN CIVIL ENGINEERING BY : JATIN ARORA, ANUJ ARORA, AKSHAY RUHIL RAHUL CHHOKAR.
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EMERGING TRENDS IN CIVIL ENGINEERING BY : JATIN ARORA, ANUJ ARORA, AKSHAY RUHIL RAHUL CHHOKAR
INTRODUCTION TO NDT’S ON STRUCTURES
WHAT IS NDT??? NDT-NONDESTRUCTIVE TEST: Detect Defects , Dimensions etc. without Damaging Material.
Impact-Echo Method It is a technique used for flaw detection in concrete surface.
Impact-Echo • Based upon evaluation of stress waves generated by an elastic impact on a concrete surface • Originally developed at Cornell University and NIST by M. Sansalone and N. Carino P – Compression waves R - Rayleigh waves S - Shear waves
Impact-Echo Propagating P-waves generated by impact event. Multiply-reflected waves are detected by surface sensor. Reflected waves set up a resonance condition having a characteristic frequency Analogous to a bell’s tone
Impact-Echo • Effective in determining thickness of slabs and depth of flaws in plate structures • Does not work on beams & columns
IMPACT ECHO • Applications • Thickness of members – d,b • Location of internal defects • Voids / delaminations • Repair quality assurance • Internal damage • ASR / DEF / ACR
IMPACT ECHO • Summary • Requires significant experience • Powerful method for flaw detection • Applications to quality control • Verification of results is critical
REBOUND HAMMER TEST OBJECTIVE : Determine the Compressive Strength of concrete.
Advantages & Disadvantages • Easy to Handle • Quick • Inexpensive • Used only on Smooth surfaces • Age of Specimen
COVER METER TESTING • OBJECTIVE : Determine Nominal cover.
PRINCIPLE • Works on Electromagnetic Pulse Induction method
ADVANTAGES & DISADVANTAGES • High Accuracy • Economical • Not Influenced by Moisture Limited Detection Range Spacing depends on Cover depth.
Refrences: Wikipedia.com Civil2010.net NIST Jounral
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