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Soil Mechanics: Relationship between pH of seawater and sand

  1. Aug 29, 2011 #1
    Is there any relationship between the pH of seawater and any properties of the sand at the beach? If so, what/ why/ how?

    Context: I am writing a report for my Soil Mechanics course, for which we analysed some sand we collected at the beach, as well as some seawater. One of the key properties to measure - as suggested by both lecturer and lab tutors - was the pH of the seawater, which leads me to believe there might be some relationship.

    I am aware that the pH of soil affects what kind of plants can grow, but this is a soil mechanics subject, not agriculture (i.e. we also have to find the angle of repose, suction, shear strength, etc...). So why bother with the pH of seawater?

    I have tried finding relevant material in the textbook for the course [Soil Mechanics and Foundations, Buhdu] but have been unsuccessful. Furthermore, my attempts at online research have lead me as far as finding the best soil pH to grow crops.

    Any insights will be very much appreciated!
  2. jcsd
  3. Aug 29, 2011 #2
    Good morning mjichael, welcome to physics forums.

    Please clarify: by soils mechanics do you mean engineering properties for structural purposes or do you mean soil science as in agriculture?

    I am not aware of any relation between sand and pH from a formation of sand point of view.

    From the point of structural engineering point of view there is a soil type called sabkha which forms in certain tropical high salinity seas such as the Red Sea.
    There is a weak chemical link between salinity and pH.
    Sabkha has interesting propeties.


    A forum search will show that both the Sabkha and the relationship between pH and salinity has been discussed here before.

    go well
  4. Aug 29, 2011 #3
    I am indeed referring to the sand's engineering properties for structural purposes.

    I didn't think there was going to be a relationship, but I thought I better ask!

    Thanks for your reply, I will be sure to check out sabkha :)
  5. Aug 29, 2011 #4
    Did you, for instance, repeat this exercise near a beach formed from calcareous rock and ask why is there no find grained beach material equivalent to sand grains?
  6. Aug 29, 2011 #5
    No we only did it once, and to my knowledge there was no calcareous rock nearby. I think that is probably beyond the scope of my course anyway, given it is just an introduction.
  7. Aug 29, 2011 #6


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    Some research has shown that the pH of the solution can effect the tensile strength for some sand soil combinations. Apparently a lower pH solution increases soil particle bonding stress and thus increases tensile strength.

    Check out: http://www.deepdyve.com/lp/springer...of-contaminated-and-compacted-sand-noOE0MPPsl

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