Journals Proceedings

Abstract

Ground penetrating radar equipped with 2 GHz high frequency bi-polar antenna was experimentally used as one of the methods for the assessment of outer stone masonry leaf of the Charles Bridge (14th century) in Prague. The applicability of the method was first studied on previously extracted masonry blocks. This allowed a more detailed study of expected defects and of various material inhomogeneities including grouting materials that were to be expected during the assessment of the real structure. These model situations were useful for determination of an optimal radar set up and also its resolution and clarification of potentials for detection of expected defects like voids, irregular detached surfaces, elevated moisture content and reflection of signal from the irregular rear plane of a stone block. It also uncovered important influences of several types of sandstones used in the structure. There have been more than seven different types of sandstone identified in the structure. The final step was a trial assessment of the masonry in situ. After the evaluation, the GPR method was recommended for the assessment of the facing stone units of the bridge.