Author : Shibli Russel Mohiuddin Khan
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (975 download)
Book Synopsis Effectiveness of Ultrasonic Pulse Velocity and Impact-echo Ndt Techniques to Assess the Quality of Concrete by : Shibli Russel Mohiuddin Khan
Download or read book Effectiveness of Ultrasonic Pulse Velocity and Impact-echo Ndt Techniques to Assess the Quality of Concrete written by Shibli Russel Mohiuddin Khan and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The deterioration of concrete in structure is a result of several internal or external degradation mechanism and which results in distress of the structure i.e. decrease in strength and integrity of the structure. the state of distress is often hidden from view and is only evident at a stage where there is significant reduction in strength of the structure. defects are open introduced during construction and are viewed during in services life. Some deterioration is viewed physically in the early age or during the services life of the structure in terms of spalling, surface crack, swelling and honeycombing. This deterioration collectively or individually results in reducing the load carrying capacity in terms of the distress of the structure. In this project, the common defects in the concrete structures and mapping techniques by nondestructive test are presented. Among the various techniques of the nondestructived tests, the Ultrasonic Pulse Velocity (UPV) and DOCtor's impact echo were chosen for their effectiveness. The UPV is used to estimate the concrete strength, detecting flaws such as voids and cracks and also to investigate the effects of smaller diameter bar in the concrete. In detecting various sizea of voids by the Impact-echo test techiniques a format was suggested to identify the from the frequency spectrum. In the bridge condition assessment by nondestructive test techniques most common problem encountered were correlationof cube crushing strength to the UPV values, in order to determine residual strength of the structure in different enviromental conditions. also the other defects such as cracks and voids in the concrete, which does not have any standard guideline to identify them by theabove NDT techniques to use in the bridge condition assessment. This project has dealt with large number of specimens between the actual condition and those of the values given by the NDT results. A number of beam specimens were also cast with known defects in the concrete in order to obtain and suggest standard investigation procedure. 108 standard cubes with different grades and enviromental conditions were cast. Also eight beams and a slab were casting having known common defects. From the strength- UPV correlation nine numbers of regression equations were suggested. A standard transducer spacing has been suggested for detecting crack depth of to 50 to 125mm range. The effect of bar sizes on UPV test results was also obtained. Reinforced concrete slabs or decks having bar diameter greater than 10mm diameter will be affect the reading of UPV. Based on the obtained resuls a computer database system for NDT has been made to accomodate and fulfill necessary requirements of knowledge base system. Hence this knowledge base system will be used for bridge condition assessment.