Acidic subsoil treatment for foundation
Acidic subsoil treatment for foundation
(OP)
Hi, I'm designing a building with basement car park. The soil resports shows the subsoil is predominantly silt down to the bedrock. The water table is up to existing ground level. My basement is 10 feet below the existing ground level. The soil pH level are:
ph 4.3 - 1.5 to 2 m below ground leve SO3 - 0.09%l
Ph 5.6 - 3 to 3.5m SO3 - 0.84%
pH 3.4 - 6 to 6.5 m S03 - 0.75%
Water sample Ph 6.2 SO3 - 0.01%
I'm planning to use Grade 80 spun pile; any treatment required?
The report stated that fly ash or sulphate resistant cement is to be used; Can I use fly ash concrete only on pilecap & basement slab. I'm planning to excavte all earth in the basement & replaced with granular material anyway. The basement wall will be normal portland cement concrete with a layer of bitumen coating. Concrete grade for pilecap is 35 & structure is 30. The pilecape is at the botoom of the basement slab level at 3m below existing ground level.
Can I do away by just applying fly sah concrete in the 3 inch lean concrete layer & use
normal portland cement concrete for the basement slab?
ph 4.3 - 1.5 to 2 m below ground leve SO3 - 0.09%l
Ph 5.6 - 3 to 3.5m SO3 - 0.84%
pH 3.4 - 6 to 6.5 m S03 - 0.75%
Water sample Ph 6.2 SO3 - 0.01%
I'm planning to use Grade 80 spun pile; any treatment required?
The report stated that fly ash or sulphate resistant cement is to be used; Can I use fly ash concrete only on pilecap & basement slab. I'm planning to excavte all earth in the basement & replaced with granular material anyway. The basement wall will be normal portland cement concrete with a layer of bitumen coating. Concrete grade for pilecap is 35 & structure is 30. The pilecape is at the botoom of the basement slab level at 3m below existing ground level.
Can I do away by just applying fly sah concrete in the 3 inch lean concrete layer & use
normal portland cement concrete for the basement slab?
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RE: Acidic subsoil treatment for foundation
I have some misgivings about your proposed method of saving on the more resistant concrete. Using only the lean mix concrete as a barrier, how long do you think the lean mix will act as a barrier in that environment? If it IS lean mix, then it will (by definition) have a lower cementitious content. If it is lean mix, I presume it will NOT be reinforced. In that case, surely you will expect it to crack significantly, offering a path for the contaminants straight to the Normal Portland Cement concrete! (I am assuming that the groundwater is also acidic, although you have only quoted results of tests on the soil.)
Remember that you have a contaminant SOURCE, and you have a TARGET (your structure and its foundation). If there is ANY PATHWAY by which the contaminant can reach the target, you need to design for that situation. Eliminate the source completely, or remove the pathway (e.g. by adequately protecting the target), or move the target away.
I would suggest that if your pile cap needs fly ash cement, then your basement slab probably does as well.
If I have misunderstood the problem, perhaps more details will encourage more responses.
RE: Acidic subsoil treatment for foundation
Spanish code EHE classify some of your pH Strong Attack Qc hence Sulphate resistant cement is enforced.
Given potential incompatibilities, EHE code only allows use of fly ash with CEM I (or pure Portland without any fill). Hence if you want to use fly ash with SR cement, I see a certificate on the compatibility of the fly ash with the cement long term in the presence of the agrressive environment would be mandatory.