ᐅ Is a concrete slab foundation impossible without a geotechnical engineer?
Created on: 14 May 2020 17:01
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Pixelsurium
Hello everyone,
For our project, a significant amount of fill was required, meaning the house will rest on an 80 cm (31.5 inches) layer of gravel, with an additional layer of up to 1.40 m (4 ft 7 in) of recycled concrete gravel underneath in some areas. The team did an excellent job compacting it and performed a dynamic plate load test. Result: Evd = 37.3 MN/m².
The concrete slab company (a major basement builder starting with K) is now refusing to proceed and is demanding values for frost depth, subgrade modulus, and stiffness modulus, which apparently only a geotechnical engineer can determine (???). I’m wondering why I would need a soil survey for a 2 m (6 ft 7 in) thick gravel layer? Can anyone shed some light on this, or is a soil report really unavoidable?
Best regards
For our project, a significant amount of fill was required, meaning the house will rest on an 80 cm (31.5 inches) layer of gravel, with an additional layer of up to 1.40 m (4 ft 7 in) of recycled concrete gravel underneath in some areas. The team did an excellent job compacting it and performed a dynamic plate load test. Result: Evd = 37.3 MN/m².
The concrete slab company (a major basement builder starting with K) is now refusing to proceed and is demanding values for frost depth, subgrade modulus, and stiffness modulus, which apparently only a geotechnical engineer can determine (???). I’m wondering why I would need a soil survey for a 2 m (6 ft 7 in) thick gravel layer? Can anyone shed some light on this, or is a soil report really unavoidable?
Best regards
Vicky Pedia14 May 2020 22:33Tarnari schrieb:
As far as I understand, it is also important for the structural engineer, who is responsible for ensuring that the building does not “tip over.” That would be for the media. From a technical perspective, settlements of just 2mm (0.08 inches) are enough to cause cracks everywhere. Therefore, no experiments in that area!
Vicky Pedia schrieb:
Well, that would be a story for the media. From a technical perspective, settlements as small as 2mm (0.08 inches) are enough to cause cracks everywhere. So definitely no experiments in that area!Vicky Pedia14 May 2020 22:51Got it already! With a concrete slab, 2 mm (0.08 inches) is enough to cause it to "tip over"!
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Pixelsurium8 Aug 2020 14:29Update: The soil analysis was eventually carried out on the recommendation of the foundation slab manufacturer. They basically performed the same procedure as the civil engineer -> dynamic plate load test and provided a frost depth value from a table. Cost was about 800€
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