Question 4 (a) Clay minerals can have a 1:1 or a 2:1 structure. Give a brief exp

Question

Question 4 (a) Clay minerals can have a 1:1 or a 2:1 structure. Give a brief explanation of the differences in these structures and how the two different structures deal with wetting. (3 mark) (b) A sample of a clay soil deposit, upon which a structure is to be constructed, has the following properties: Total Volume 100 cm3 Total Mass =170grams Moisture Content (mass basis) 16% Specific Gravity of Solids 2.70 i. Calculate the relative proportions, on a volume basis, of solid, water and air in the sample (9 mark) ii. The sample was then soaked for a day and the total volume increased to 105cm, witha corresponding increase in moisture content (mass basis) to 32%. Is the sample now fully saturated? You have to justify your answer with relevant calculations (3 marks) Note: In your calculation, you can assume density of water = 1 g/cm'

Explanation / Answer

a)

Clay minerals are the feature minerals of the earths close to exterior environment. They shape in soils and sediments, and by diagenetic and hydrothermal change of rocks.

Water is necessary meant for clay mineral arrangement and mainly clay minerals are describe as hydrous alumino silicates.

Structurally, the clay minerals are collected of plane of cations, in order in sheets, which may be tetrahedrally or octahedrally coordinated (with oxygen), which in turn are orderly into layers often describe as 2:1 if they involve units collected of two tetrahedral and one octahedral sheet or 1:1 if they involve units of alternating tetrahedral and octahedral sheets.

Additionally some 2:1 clay minerals have interlayers sites among consecutive 2:1 units which may be busy by interlayer cations, which are often hydrated.

The planar arrangement of clay minerals give go up to trait platy custom of many and to ideal cleavage, as seen for instance in big hand specimen of micas.

The categorization of the phyllosilicate clay minerals is bottom together, on the kind of coating type (1:1 or 2:1), the dioctahedral or trioctahedral nature of the octahedral sheets (i.e. 2 out of 3 or 3 out of 3 sites occupied), the scale of any net unenthusiastic layer accuse due to atomic substitution, and the scenery of the interlayer fabric.

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