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Federal Highway Administration > Publications > Public Roads > Vol. 71 · No. 6 > 508 Caption

Nov/Dec 2008
Vol. 71 · No. 6

Publication Number: FHWA-HRT-09-001

508 Caption

CSL Resulsts: Figure and Photo. This image depicts CSL results. In the middle left is a vertical color code showing the velocity ranges, labeled "Velocity Contours" with a plus sign on top and a minus sign on the bottom of the column. Red is the first color on the spectrum, indicating good quality. Moving down the column, the red turns to yellow and then green in the middle, where the number 0 is labeled at the center of the column, then turns to blue and then purple at the bottom, beside the minus sign, indicating poorer quality. A taller vertical column is to the right of the color spectrum. This column represents sonic velocity measurements made between three hollow tubes installed vertically in one drilled shaft filled with concrete. The column is seen against a field of red with horizontal black lines indicating cross sections marking off depth. Within the column, three vertical CSL tubes (smaller columns) are shown from left to right as red, blue, and green, running the length of the column. A bulbous green shape near the top of the column shows the zone with 10 percent velocity reduction. Beside the green shape is the text "Questionable zone with 10% velocity reduction." A rounder purple shape near the middle of the column shows the zone with 20 percent velocity reduction and is labeled with the text "Defect zone with 20% velocity reduction." From this middle shape, an arrow points down and to the right to a closeup of the defect. This defect is shown as a purple shape within the interior of a section of the column with the red, blue, and green CSL tubes running vertically through it. Below the defect is the text "Closeup of image defect." Above the defect is a photograph showing two workmen in the background using the CSL equipment. In the foreground of the photograph are vertical pieces of reinforcing steel, with the three larger CSL tubes attached to them. In the top of the two left CSL tubes, the CSL cables are shown as they are inserted, where one side is the transmitter, and the other side is the receiver.

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