water content of soil

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  • 7/29/2019 Water Content of Soil

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    HASHEMITE UNIVERSITYFaculty of Engineering

    Civil Engineering Department

    Dr. Faisal ShalabiEng. Hussein

    AHMED HANI SALEM AL-OMARICivil Engineering431900

    Ahmed Hani Salem Al-OmariID # 431900

    Civil Engineering just4just.com/ahmed

    Objective:

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    - The objective of this experiment is to calculate the percentage of water in

    some specific amount of soil in term of its dry mass.

    - We do this experiment because we know then the moisture content and

    from that we do our work or construction based on the water content because this

    property is so important.

    General Discussion:

    - We can define the water content as the ratio of the mass of water present

    to the total mass (water + soil).

    - Experience indicates that this method of sample drying is sufficient for the

    small samples (10 to 200 g) used in routine laboratory work. It is usual adequate

    for much larger samples, 1000 g or more, but large samples be stirred

    occasionally so uniform drying is obtained.

    - It is usual to remove the water content samples from the oven and weigh

    them immediately (we use heat-resistant gloves because they are hot).

    - The oven temperature of 1100 C is too hot for certain organic soils, soils

    containing appreciable amounts of gypsum or some other minerals, certain clays,

    and some tropical soils.

    .

    Equipments:

    - Moisture tin cups.

    - Oven with accurate temperature control at 110 5 c.

    - Balance, sensitive to 0.01g.

    Procedures:

    - We get a clean can and weight it as an empty one and get the reading.

    - We put a representative sample of wet soil in the cup and determine the

    mass of wet soil + can.

    Note: if the mass is determined immediately, it is usually not necessary to place the

    lid on the cup. But if there is a delay of 1 to 5 min or more, put the lid on the can so

    soil does not dry and place the cup under a damp paper towel to maintain the

    humidity in its vicinity.

    Ahmed Hani Salem Al-OmariID # 431900

    Civil Engineering just4just.com/ahmed

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    - After weighing the wet sample + can, remove the lid- it is usual practice to place it

    under the bottom of the can- and place the sample in the oven.

    - After drying the sample to a constant mass and after two days we get the reading

    of the weight of dry soil + can.

    Calculations:

    - Sample of calculations :

    Wt. water (WW) = = gWt. dry soil (WS) = = g

    Moisture content (percent) (W %) = ( / ) * 100 %= %

    - Data sheets :

    SOIL MOISTURE CONTENT DETERMINATION

    Can Number 2A G2

    1) Soil type sand clay

    2) Wt. of can ( can weight) (g) 30 30.7

    3) Wt. - wet soil + can - (g) 77.55 84.94

    4) Wt. - dry soil + can - (g)

    5) Wt. water - ( line 3 - line 4) WW (g)

    6) Wt. - dry soil - ( line 4 -line 2) WS (g)

    7) Moisture content (line 5 line 6) W(%)

    Ahmed Hani Salem Al-OmariID # 431900Civil Engineering just4just.com/ahmed

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    Discussion & Conclusions:

    - Discuss results :

    - From this test we see that the water content of Clay is bigger than the sandone :

    Clay = %Sand = %

    And that because the bond (or cohesive ) between the particle of twoof them and the size of these particle.

    - The voids maybe occupied by either air or water or mixed the water molecules in thevoid make the water content and its different from soil to another. So its depend on type

    of soil.

    - Errors :

    After drying the soil in oven, if the mass appears to be in error, first reweigh the can +

    dry soil, and, if the new value appears satisfactory, continue. If it is not, next check if

    you are using the same moisture and/or if they are in adjustment: also be sure the lid is

    included if a metal moisture can is being used.

    If these items all check and there is too much mass, you will have to discard this sample

    because it is impossible for a "dry" sample to have a greater mass than a "wet" one (an

    earlier weighing error has been made).

    There may still be a weighing error, but at this point you have no means to identify it.

    There is an error in the value of the soil weight, results from unadjusted balance, and

    error in the period of time the sample was had in the oven to dry.

    - Improvement :

    When we heat some soils it might be changed in its characteristics. ASTM suggests anoven temperature of 600 C for drying these soils.

    SAFETY: this test may be hazardous if the soil being dried contains certain chemicals.

    For us as a student laboratories reliable soil sources should be used to avoid creating a

    hazardous environment

    Moisture content is one of the most important quantities in soil mechanics, because it's

    easy to be evaluated in a lap, and the whole foundations of buildings depend on it.