How can you measure the depth of removal?What depth of removal should be specified?How should the depth of removal be specified? Hydrodemolition creates a very rough surface profile, which generally ranges ± ˝ the diameter of the coarse aggregate. As a result there are three different possible depth measurements:1. Minimum Removal – Original surface to the shallowest removal point.2. Maximum Removal – Original surface to the deepest removal point.3. Average depth of Removal – The difference between the minimum and maximum removal at the same location. Measuring the depth of removal can be accomplished using:1. A straight-edge placed on the original surface2. A string-line pulled over the removal area3. A surveyor’s levelThe most common practice of measuring the depth of removal is to place a straightedge on top of the original surface and extend it over the removal area. Measurements are taken from the bottom of the straightedge to determine the depth of removal. This quick and simple technique can only be used during the removal process, and is not applicable for final measurements in large removal areas. Rampart’s hydrodemolition technicians normally check the depth of removal using this method as the hydrodemolition proceeds. Using this method allows the technician to make adjustments in the equipment to insure that the specified removal is accomplished.
A string line may be pulled over the removal area and measurements taken below the string. However, this method could provide incorrect results if slopes or crowns occur in the original surface. Surveying equipment may be used and is very accurate; however, to account for slopes, pitches and crowns in the original surface, a detailed survey must be made of the original surface prior to removal and measurements taken at the same locations after removal for comparison and determination of the actual removal depth.
