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Pitiglianio27 Jul 2022 15:48Hello. Maybe someone here has already dealt with a similar problem.
For our single-family house on a slope, we followed the foundation recommendations according to the geotechnical report.
There is 40cm (16 inches) of recycled gravel laid in two layers and compacted on rocky ground. The structural engineer requested a plate bearing test at two points, which failed on the first try. The recommendation was to moisten and compact further. That was done. The second test also narrowly failed.
We moistened and compacted again. Unfortunately, the third test failed as well.
Here are the values from the plate bearing tests:
First attempt:
EV1: 99.2 MN/m²
EV2: 36.1 MN/m²
EV2/EV1 = 2.75
Second attempt:
EV1: 45.1 MN/m²
EV2: 118.4 MN/m²
EV2/EV1 = 2.61
Third attempt:
EV1: 45.3 MN/m²
EV2: 118.4 MN/m²
EV2/EV1 = 2.61
The value EV2/EV1 must be less than or equal to 2.5 to meet the requirements.
The compactor used is a 500kg (1,100 lbs) Wacker DPU. Is this generally sufficient, or do we need to bring in heavier equipment?
What was your experience, and what can we do?
For our single-family house on a slope, we followed the foundation recommendations according to the geotechnical report.
There is 40cm (16 inches) of recycled gravel laid in two layers and compacted on rocky ground. The structural engineer requested a plate bearing test at two points, which failed on the first try. The recommendation was to moisten and compact further. That was done. The second test also narrowly failed.
We moistened and compacted again. Unfortunately, the third test failed as well.
Here are the values from the plate bearing tests:
First attempt:
EV1: 99.2 MN/m²
EV2: 36.1 MN/m²
EV2/EV1 = 2.75
Second attempt:
EV1: 45.1 MN/m²
EV2: 118.4 MN/m²
EV2/EV1 = 2.61
Third attempt:
EV1: 45.3 MN/m²
EV2: 118.4 MN/m²
EV2/EV1 = 2.61
The value EV2/EV1 must be less than or equal to 2.5 to meet the requirements.
The compactor used is a 500kg (1,100 lbs) Wacker DPU. Is this generally sufficient, or do we need to bring in heavier equipment?
What was your experience, and what can we do?
Well, the uncertainty regarding recycled gravel could be the cause. For example, we were not allowed to use it at all. Our building planner would have outright rejected it as well (he kindly informed us of this in advance ;-). I am in favor of recycling, but if you take a closer look at the debris and the amount of organic material in recycled gravel, compaction can definitely become problematic.
Of course, I am not a clairvoyant, but why not ask the parties involved about their opinion on the matter mentioned above.
Of course, I am not a clairvoyant, but why not ask the parties involved about their opinion on the matter mentioned above.
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Pitiglianio27 Jul 2022 16:57i_b_n_a_n schrieb:
... The uncertainty regarding recycled gravel could be the cause. For example, we were not allowed to install it at all.What did you use instead?
schubert7927 Jul 2022 17:39A friend of mine had the same issue. It was due to the recycled gravel. It simply wasn’t suitable for compaction. It was removed and replaced, and then there were no problems at all.
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Stefan00129 Jul 2022 10:05I am absolutely not an expert in this field, but does recycled gravel even have an "approval" for such applications? I vaguely remember that during our construction, the general contractor mentioned that some things might not be allowed to use recycled materials...
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