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I am building a pole barn garage/storage building with a 4″ concrete slab floor. It needs to be filled in with about 3″ to 6″ of pea gravel or sand prior to pouring the concrete. My question is do I need to have a backhoe come in and scrape off some of the top layer of dirt/grass. This will cause me to need more fill gravel and seems like it would be disturbing the existing ground that will be under the slab. Would it be better to just leave the existing area undisturbed and just kill off the grass with say Roundup or something and then put my gravel or sand fill right on the undisturbed ground. Any advice on this would be much appreciated.
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Hi Harry,
Without the slightest doubt, you HAVE TO remove all organic material, BEFORE you put down your pea stone and compact for your concrete slab on grade.
Otherwise, I can guarantee, your slab WILL crack and settle.
Gabe
*Sorry Harry but Gabe's right on this one :). If your looking to practic your skills in concrete repair then pour on, if not then remove that layer and compact!!!!!
*Harry,There are two kinds of concrete. Concrete that has cracks and concrete that is going to crack. Considering your investment in materials it makes good sense to invest a little more to ensure that your floor will placed over a stable base that will not move. This does two things. It reduces stress on the slab and it holds the slab in a level plane if (and when) cracks appear. Most cracks in concrete are the result of expansion and contraction as temeratures change. However, once a crack is induced an unstable base will make things worse.
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I am building a pole barn garage/storage building with a 4" concrete slab floor. It needs to be filled in with about 3" to 6" of pea gravel or sand prior to pouring the concrete. My question is do I need to have a backhoe come in and scrape off some of the top layer of dirt/grass. This will cause me to need more fill gravel and seems like it would be disturbing the existing ground that will be under the slab. Would it be better to just leave the existing area undisturbed and just kill off the grass with say Roundup or something and then put my gravel or sand fill right on the undisturbed ground. Any advice on this would be much appreciated.