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<br />002448 <br /> <br />Durango Pumoing Plant - Stage 1 <br /> <br />J. Measuring Surface Roughness: <br /> <br />I. Examples below illustrate how to make necessary surface measurements for <br />typical roughness. <br /> <br />2. Case 1 - Roughness Protruding above Surface: <br /> <br />a. A roughness protruding above the surface should be measured with a <br />straightedge that is at least 20 times longer than the roughness height <br />being measured. <br /> <br />b. Position the straightedge with one end resting on top of the roughness, as <br />shown in Figure 2 (case 1). <br /> <br />c. Determine the roughness height by measuring the maximum gap that <br />occurs normal to the straight edge. <br /> <br />d. Note the position on the straightedge from which the normal distance is <br />measured. <br /> <br />e. To determine the roughness length, measure the distance along the <br />straightedge from the point where the height was measured to the point of <br />contact between the straightedge and the top of the roughness. <br /> <br />f. The roughness slope is defined as the ratio of the roughness height to the <br />roughness length. <br /> <br />g. As roughness is seldom symmetric, moving the position of the <br />straightedge about the roughness may be necessary to locate the point <br />where the maximum height and slope exists. <br /> <br />3. Case 2 - Roughness Extending below the Surface: <br /> <br />a. A roughness occurring as an indentation to the surface is measured by <br />placing the straightedge across the indentation, as shown in Figure 2 (case <br />2). <br /> <br />b. Measure the maximum gap between the straightedge and the surface and <br />note the location of the measurement on the straightedge. <br /> <br />c. From the point of the depth measurement, measure along the straightedge <br />in both directions to the point of contact with the surface. <br /> <br />d. The shortest length measured is used as the roughness length. <br /> <br />e. Divide the roughness depth by the roughness length to determine the <br />roughness slope. <br /> <br />4. A simple measuring device can be constructed to perform surface tolerance <br />measurements and evaluation process directly and quickly. Information <br />concerning concrete tolerance measuring devices can be obtained from Bureau of <br />Reclamation, Attn D-8180, PO Box 25007, Denver CO 80225-0007, telephone <br />(303) 445-2399. <br /> <br />Cast-in-Place Concrete <br />03300 - 44 <br />