Concrete interlayers

April 1st, 2021

Q: We are interested in using a geotextile as an “unbonded concrete interlayer” over existing concrete pavement to float the new slab over deteriorated pavement, instead of a thin asphalt layer. Do you have any guidance for us in this regard? A: Over the past several years, 16-ounce-per-square-yard (542-g/m2) nonwoven needlepunched geotextiles have been used […]

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GRI-GM19 peel specification

April 1st, 2021

Q: Our liner system is a double composite and along a western tie-in. We need to extrusion-weld the secondary 60-mil (1.5-mm) HDPE (new cell) to an existing secondary 40-mil (1-mm) HDPE (old cell), and the state is continuing to have issues with the fact that we are using the 40-mil (1-mm) GRI-GM19 peel specification as […]

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Installing a geomembrane low to high gradient?

April 1st, 2021

Q: We are a large liner installation firm that has been asked to install a geomembrane liner from low gradient to high gradient. Is this the new normal? A: This is not normal, and we suggest you strongly object to this recommendation. There are many stakeholders in regard to panel layout (i.e., installer, general contractor, […]

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Geomembranes for reinforcement?

April 1st, 2021

Q: We are using Robert Koerner’s Designing with Geosynthetics to calculate the required thickness of a geomembrane. See Figure 1 and Equation 1 from the book for details. Figure 1 Equation 1 Can you point us in the right direction with the mobilization distance, x? A: Yes, please see Figure 2 for high-density polyethylene (HDPE). […]

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Anchors, tie-rods and whalers

April 1st, 2021

Q: We are having issues related to obstructions in the reinforced zone of our mechanically stabilized earth (MSE) retaining walls. In the first case, there is a rock outcrop that is limiting the length of the geogrid reinforcement. In the second case, we have a drop-down inlet structure to divert stormwater, which is in the […]

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