The Impact-Echo Method
Contents
1. 3 hours of operating time and extra batteries are available The data acquisition system battery provides 6 8 hours of operating time when fully charged Power supplies for recharging the batteries from a 110 220v AC source or a 12v DC source such as a car or truck battery are included 9 October 2003 Roll On Carry On Case The heavy duty padded roll on canvas case has a separately padded computer pocket zippered accessory pockets padded container for transducer units zippered mesh pockets telescoping handle and in line skate wheels When fully packed its dimensions are approximately 18 x 14 x 10 inches 46 x 36 x 25 cm and its total weight is about 30 pounds 13 6 kg Computer Recommendations for Impact Echo Test Instruments A Test System can be purchased from Impact Echo Instruments with or without a computer The IMPACT E software program requires an IBM compatible computer with a Windows 95 or later operating system a serial port or USB port available on virtually all computers and English U S as an available option for both the Regional Setting and the Keyboard Language these settings are found in the Control Panel of Windows operating systems The minimum recommended capabilities for an IBM compatible computer are as follows 100 Mhz or faster processor 10 3 TFT color screen 16 MB RAM 3 5 Floppy disk drive OO MR Hard Drive Virtually all currently available BM compatible computers2. Help Exit The Main Menu screen of Impact E software Software for Impact Echo Key Features Easy to use e User interacts through clearly labeled command buttons and text boxes for data entry e Control exercised with mouse or keyboard or combination of the two e Organization of screens guides the user through testing and data recall and analysis e Date and time of each test automatically recorded and stored with test results e Sets up for testing in two minutes e Test results appear on the computer screen within 2 seconds after impact is made e The time required to perform a test and store the results in a test file is 15 20 seconds Flexible e Screens can be viewed in color or black and white the latter is sometimes easier to read in outdoor light e Test results can be stored in data files on hard disk floppy disk or other drive for later recall and analysis e Test records and summaries of test files can be printed or written to Excel spreadsheets e File utilities system facilitates printing copying test records between files writing information directly to Microsoft Excel spreadsheets writing results to ASCII files for export etc Software Protection e Impact E software is protected against unauthorized use by encrypted code that enables testing to be performed only with a compatible data acquisition system from Impact Echo Instruments LLC 9 October 2003 The Book Impact Echo Nondestructive Evaluat
3. coaxial connector for power supply Dimensions amp Weight 10 2 x 6 2 x 1 6 inches 26 x 16 x 4 cm and 2 2 pounds 1 0 kg Warranty All components with the exception of the computer are covered by a one year parts and labor warranty from Impact Echo Instruments LLC Warranties for computers are provided by the manufacturer 9 October 2003 Impact E Windows Based Software For Impact Echo Impact E is a Windows based interactive user friendly software system for impact echo testing and for examination and analysis of impact echo test results It is the product of two man years of programming effort by the people who wrote the book on impact echo see p 8 It incorporates the physics and mathematics on which the impact echo method is based Impact E software can be installed on any computer and used for all purposes except testing which requires a data acquisition system from Impact Echo Instruments that 1s compatible with the software Key benefits of Impact E software Impact E e User friendly Guides the user through the testing process e Interactive The user is in control at every Step e Well documented Main Menu Comprehensive instruction manual and a detailed on line Open Test Data File Describe Structure Parae ee Help System e Measure Depth of Surface i e Comprehensive Covers all iieii Opening Crack known applications of impact Examine Test Data File Utilities Program Parameters echo
4. from Impact Echo Instruments to locate voids beneath 80 90mm of a steel fibre concrete floor forming the cap over cushion piles We have located faulty pile heads mapped the extent of voids and associated honeycombing and after grouting checked for residual voids and concrete strength gain No other available test method is appropriate We also regularly use impact echo in forensic studies of historic buildings including recently St Paul s Cathedral London The Federal Reserve Building in New York and the U S Capitol Building Washington George Ballard GBG Inc New York USA GB Geotechnics Ltd Cambridge England The Federal Highway Research Institute of Germany BASt has used the equipment of Impact Echo Instruments for almost two years The impact echo system was used successfully for thickness measurements detection of delaminations and detection of voids and honeycombing Furthermore the system was used for the investigation of prestressed concrete bridges to detect voids in the grouting of tendon ducts For verification of the thickness of the inner tunnel lining of new road tunnels in Federal Roads a procedure based on the use of impact echo was prepared by BASt and implemented by the Federal Ministry of Transport Building and Housing Dr Ing Juergen Krieger Bundesanstalt fuer Strassenwesen Federal Highway Research Institute Germany We have used the impact echo method successfully in 13 projects since June 199
5. meet or exceed these requirements Suitable notebook computers are available from many companies including Acer Compaq Gateway Dell HP IBM Micron Panasonic Toshiba Winbook and others The Panasonic Toughbook is a ruggedized computer that has a moisture and dust proof magnesium alloy case shock mounted hard drive spill proof keyboard sunlight readable screen and other features well suited to outdoor use See the Panasonic web site listed below or search for Toughbook on the Internet Prices for notebook computers that meet or exceed the minimum requirements for use with an impact echo test system start at about US 1000 Ruggedized computers start at about 2000 For current information see the following web sites http www acer com aac http www pc ibm com thinkpad http www compaq com http www micronpc com http www gateway com http www panasonic com computer notebook http www dell com http www toshiba com http www hp com http www winbook com See pages 10 11 for detailed information on instrument configurations and prices with and without computers 9 October 2003 Technical Specifications for the Impact Echo Test System The instrument was designed and tested for worldwide use It carries the CE s mark of conformity with European Union standards C Dimensions and Weights When fully packed the carrying case is approximately 18 x 14 x 10 inches in size 46 x 36 x 25 cm Total weight including n
6. negotiable on a U S bank The book can also be ordered Phone or Fax 570 769 7345 from http www amazon com Surface Priority S First Copy Additional First Copy Additional J52 50 4 00 4 00 9 October 2003 Testimonials from engineers who have used our instruments worldwide WDP has successfully utilized equipment from Impact Echo Instruments LLC to investigate a wide variety of civil infrastructure over the last 10 years ranging from bridges parking structures and buildings to specialty structures such as tanks storm water retention boxes flood control channels and marine structures Flaws such as delaminations honeycombing and voids in concrete voids in grout of bonded post tensioning tendons and sub grade voids under slabs have been successfully detected and confirmed using this technology Impact Echo has been used by WDP on over a hundred structures in the evaluation of thousands of individual concrete members Over 100 000 signals have been recorded and analyzed over the last 10 years Impact Echo has become the leading investigative tool used by WDP personnel in the forensic evaluation of structural concrete The successful application of this technology and its ability to accurately detect concrete flaws has resulted in the savings of tens of millions of dollars in repair and replacement costs for our clients Randall W Poston Ph D P E Principal WDP amp Associates Inc Austin TX We are using an instrument
7. 9 These included detecting voids in tendon ducts in pre stressed beams and slabs determination of retaining wall thickness detection of honeycombing in basement wall and marine spun piles verified by cores determination of bonding between metal inserts and concrete in railway ties verified by cores and 5 determination of bonding condition between topping concrete and a pre cast hollow core slab Zheng Yonghao SETSCO Services Pte Ltd Singapore Based on our experiences with the technology we strongly recommend the use of Impact Echo as an effective tool to determine the likelihood of flaws within plate type structures including garage slabs plaza deck slabs and foundation walls It is particularly valuable when there is a concealed surface on the structure e g the topside of a plaza deck slab Alan Cohen Halsall Engineers Consultants Toronto Canada As an impact echo researcher I am very impressed by the products of Impact Echo Instruments with which I have done many impact echo tests successfully such as crack detection and thickness measurements A test system integrating two handheld transducers a 14 bit A D converter and a user friendly software makes the impact echo field test system accurate and easy to use Professor Yiching Lin Ph D National Chung Hsing University Taiwan
8. 9 October 2003 Impact Echo Instruments LLC Field Instruments for Nondestructive Evaluation of Concrete amp Masonry From the people who wrote the book on impact echo p 7 Impact Echo Instruments LLC P O Box 3871 Ithaca NY 14852 3871 U S A Ph 1 607 738 1547 Fax 1 607 533 7667 2 e mail weber impact echo com I F I Visit our web site at www impact echo com 9 October 2003 The Impact Echo Method Impact Echo is a method for nondestructive evaluation of concrete and masonry based on the use of impact generated stress sound waves that propagate through the structure and are reflected by internal flaws and external surfaces Impact Echo can be used to make accurate nondestructive ASTM approved measurements of thickness in concrete slabs and plates ASTM Standard C 1383 98a It can also be used to determine the location and extent of flaws such as cracks delaminations voids honeycombing and debonding in plain reinforced and post tensioned concrete structures It can locate voids in the subgrade directly beneath slabs and pavements It can be used to determine thickness or locate cracks voids and other defects in masonry structures where the brick or block units are bonded together with mortar Impact echo is not adversely affected by the presence of steel reinforcing bars How Impact Echo Works Data uisitioti System ard See j Schematic diagram illustrating how impact echo works A short durati
9. ds Spacer bar with connecting handle for measurement of wave speed using two cylindrical transducers Computer Software CD not shown in photo Impact E Operating Software Wave Animation Software computer simulation of stress wave propagation and reflection Two BNC Cables for connecting transducer units to data acquisition system Serial Port Cable to connect Data Acquisition System to serial port or USB port of computer Output Adapter 90v 264v AC input 12v DC output to recharge batteries and provide power for Data Acquisition System DC to AC Power Inverter 10v 15v DC input 110v AC output for use with item 8 to recharge batteries and provide power for the Data Acquisition System Connects to cigarette lighter in car or truck Printed Materials Book Impact Echo Nondestructive Evaluation of Concrete and Masonry by M J Sansalone and W B Streett Bullbrier Press Ithaca NY 1997 339pp Impact Echo Instrument Manual instructions for use of impact echo test system Impact Echo User s Manual self teaching course on impact echo for use with Impact E software Packing List Read Me First Warranty Roll On Carry On Case see next page Notebook Computer see next page Power Requirements Power is provided by internal batteries in the notebook computer and data acquisition system No external power source is required for operation in the field A fully charged notebook battery typically provides 2
10. ion of Concrete and Masonry by Mary J Sansalone and William B Streett Bullbrier Press 1997 339 pp Chapter Titles Introduction Development of the Method Stress Waves Waveforms Frequency Analysis Digital Signals Wave Speed Plate Thickness Cracks and Voids in Plates 0 Shallow Delaminations 1 Unconsolidated Concrete 2 Surface Opening Cracks _ 13 Plates in Contact With Soils 14 Plates Containing Two Layers 15 Bond Quality at Internal Interfaces 16 Plates With Asphalt Overlays i eer a Bars Tend Bonded Post Tensioning Tendons 19 Hollow Cylinders IMPAC T ECHO 20 Mine Shaft and Tunnel Liners 21 Circular and Square Cross Sections 22 Rectangular Cross Sections 23 Masonry 24 Field Testing This book draws together all available knowledge of the impact echo method and presents it in a concise and logical format Following a brief introduction and review of the development of the method 5 chapters are devoted to physical and mathematical principles followed by 17 chapters on applications and case studies Photographs drawings and results from tests on real structures are used throughout See ee Nondestructive Evaluation of Concrete and Masonry Mary J Sansalone William B Streett Price US 35 00 Credit card orders accepted Order from l A Bullbrier Press Bullbrier ships promptly upon receipt of payment R R 1 Box 332 Foreign orders must include payment in a form Jersey Shore PA 17740 USA
11. on mechanical impact produced by tapping a small steel sphere against a concrete or masonry surface produces low frequency stress waves up to about 80 kHz that propagate into the structure and are reflected by flaws and or external surfaces The wavelengths of these stress waves are typically between 50mm and 2000mm longer than the scale of natural inhomogeneous regions in concrete aggregate air bubbles micro cracks etc As a result they are only weakly attenuated and propagate through concrete almost as though it were a homogeneous elastic medium Multiple reflections of these waves within the structure excite local modes of vibration and the resulting surface displacements are recorded by a transducer located adjacent to the impact The piezoelectric crystal in the transducer produces a voltage proportional to displacement and the resulting voltage time signal called a waveform is digitized and transferred to the memory of a computer where it is transformed mathematically into a spectrum of amplitude vs frequency Both the waveform and spectrum are plotted on the computer screen The dominant frequencies which appear as peaks in the spectrum are associated with multiple reflections of stress waves within the structure or with flexural vibrations in thin or delaminated layers The fundamental equation of impact echo is d C 2f where d is the depth from which the stress waves are reflected the depth of a flaw or the thickness of a
12. otebook computer manuals case cables etc is about 30 pounds 13 6 kg The roll on carry on case meets requirements for airline carry on luggage It contains a heavily padded inner compartment for storage and protection of a notebook computer Hand Held Transducer Unit Key components include piezoelectric crystal and on board preamplifier Cylindrical stainless steel Pistol Grip Power Requirements 9v battery inside body of transducer Controls Armed by depressing handle cylindrical or by trigger switch pistol grip Warning light for low battery Cable Connections BNC connectors for connecting to data acquisition system Dimensions amp Weights Cylindrical Overall length is 11 3 29 cm main cylinder is 2 in diameter and 6 8 long 5 x 17 cm handle is 1 5 in diameter and 4 5 long 3 8 x 11 4 cm Weight is 2 2 pounds 1 kg Pistol Grip Height 6 5 16 5cm Length 8 20cm Width 3 7 6cm Weight 1 5 pounds 0 7 kg Analog Digital Data Acquisition System Fourteen bit analog digital converter Maximum sampling speed 2 MHz on each of two channels Power Requirements Internal rechargeable battery Sv DC provides 5 8 hours of operating time on a full charge Software Proprietary on board software functions only with Impact E operating software next page Controls On off switch indicator lights Cable Connections Two BNC cable connectors for transducer units one 9 pin serial port connector
13. puter the system on the left weighs about 13 Ibs 5 9kg and the system on the right weighs about 18 Ib 8 2 kg Teg Single Pistol Grip Transducer Dual Pistol Grip Transducer Pistol Grip Transducers The cylindrical transducers are especially useful for work in narrow and confined spaces An alternative to the cylindrical transducers called pistol grip transducers is shown in the photos above The single pistol grip model is well suited to use on flat surfaces The dual pistol grip transducer on the right is used for wave speed measurements The two sensing elements in the dual pistol grip transducer are separated by the same fixed distance 300mm as in the two cylindrical transducers held by a spacer bar right photo at the top of the page The dual pistol grip transducer eliminates the need to strap two cylindrical transducers into a spacer bar for wave speed measurements Pistol grip transducers have a trigger arming switch positioned on the underside of the grip not visible in these photos Instruments are available with several combinations of cylindrical and or pistol grip transducers eee ve Pada 10 11 12 9 October 2003 Components Analog Digital Data Acquisition System 14 bit resolution 2 MHz maximum sampling speed on each of two channels Two Hand Held Transducer Units cylindrical or pistol grip or combination of the two Impactors set of 10 hardened steel spheres on spring ro
14. solid structure C is the wave speed and f is the dominant frequency of the signal The frequency f is obtained from the results of a test To determine thickness or depth of a flaw the wave speed C must be known It can be measured by observing the travel time of a stress wave between two transducers held a fixed distance apart on the concrete surface see next page or by performing a test on a solid slab of known thickness and observing the dominant frequency In the latter case the equation is rearranged to give C 2df where d is the known thickness 9 October 2003 Test Instruments Available from Impact Echo Instruments LLC Designed by the people who wrote the book on impact echo p 7 Impact Echo Testing Wave Speed Measurement Instrument Configurations Two configurations of the instrument are shown above The principal components are hand held transducer units the cylindrical devices on the left in each photo a set of spherical impactors hardened steel ball bearings on steel rods in front of computer a high speed analog to digital data acquisition system box at left of computer a notebook computer and a software system that guides and controls the tests and displays the results in graphical and numerical form A single transducer is used for routine testing Two transducers separated by a fixed distance are used for independent measurements of wave speed photos at right above and right below With a 7 5 1b notebook com
Download Pdf Manuals
Related Search