ANALISYS OF GPR SIGNALS WITH 400 MHz FREQUENCY ON CORRODED STEEL BAR

• Main Author: Damora (NIM 25004017), Franky
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/6129
• Institution: Institut Teknologi Bandung

ABSTRACT: <br /> <br /> <br /> <br /> <br /> <br /> <br /> Concrete block with embedded steel bar spesimens have been investigated using GPR (ground penetrating radar) with 400 MHz frequency in this research. GPR signals are acquired when steel bars are in good condition and when steel bars are corroded. These signals are analized to identify the reflected waveform, to figure out the effect of chloride on reflected waveform on corroded steel bars, to figure out the peak amplitude and two way travel time of reflected waveform on corroded steel bars with variation in depth and corrosion rate, and to obtain relative dielectrict constant values of concrete before and after corrosion. <br /> <br /> <br /> <br /> <br /> <br /> <br /> Three concrete block specimens have been prepared in this research, these are; two specimens with configuration based on Standard Method Test ASTM Designation G 109 92 that are made of normal concrete mixture without NaCl solution and with 2percent NaCl solution, and specimen with special configuration and six steel bars embedded in different depth that is made of normal concrete mixture without NaCl solution. Accelerated corrosion is conducted on steel bars by applying the DC current in five sequence of periodes. GPR signals are collected after corrosion process of each periode. <br /> <br /> <br /> <br /> <br /> <br /> <br /> The analisys of GPR signals shows that two way travel time or velocity of electromagnetic wave increases in every periode of corrosion process due to parts of oxided iron in concrete surrounding steel bars. Peak amplitude on steel bars also increases in every periode because of descending of concrete conductivity. The increasing of two way travel time or velocity of electromagnetic wave indicates the increasing of relative dielectric constant of concrete during corrosion process.