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SAND
 Definition
Sand is a loose, fragmented, naturally-occurring material consisting of vary small particle
(fine to medium sized particle between 0.06mm and 2.0 mm) of decomposed rocks, corals or
shells.
Sand particles are formed by the breakdown of crystalline igneous and metamorphic rocks or
from existing sandstone. Mineralogically, sands commonly consist of quartz, feldspers, mica
and limestone.

Figure: Sand
 Classification of Sand
 Classification based on source
Sand is usually obtained from pits, shores, river beds and seas. There are mainly three kinds
of sands in use:
Pit Sand
 Obtained by pit dredging in the floodplain and lakesides.
 It is sharp, angular, homgeneous and free from harmful salts.
 Clay & other impurities should be washed and screened before using in
engineering purpose.
 Fine pit sand, when rubbed between fingers, should not leave any stain on it.
Stains indicates the presence of clay.
 Used for the mortars.
River Sand
 Found at river beds and banks.
 Fine, round and polished due to rubbing action of water currents.
 Having less frictional strength because of roundness.
 Almost white in color.
 Grains are smaller than pit sand and hence more suitable for plastering work.
 Normally available in pure condition and hence can be used for all kinds
of civil engineering works.

Compiled by Md. Ashif Rayhan Shuvo, Lecturer, Department of CE, AUST

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Sea Sand
 Obtained from sea shores.
 Fine, rounded and polished due to rubbing action of water.
 Light brown in color.
 Worst of the three types of sand because of containing lot of salts.
 Salts absorb moisture from atmosphere and cause permanent dampness and
efflorescence in the structure.
 Sea salt also retards the setting action of cement.
 Besides, it might contain shells and organic matter which decompose in the
body of mortar and concrete, and hence reduce their life and strength.
 Sea sand should as far as possible be discarded.

(a) (b) (c)

Figure: (a)Pit Sand (b)River Sand (c) Sea Sand
 Classification based on Size
Sand is divided into five sub-categories based on size:
 Very fine sand (1/16mm – 1/8mm)
 Fine sand (1/8mm – 1/4mm)
 Medium Sand (1/4mm – 1/2mm)
 Coarse sand (1/2mm – 1mm)
 Very Coarse sand (1mm – 2mm)

 Classification based on Fineness Modulus

Sand is divided into three categories based on Fineness Modulus
 Fine Sand (FM: 2.2-2.6)
 Medium Sand (FM: 2.6-2.9)
 Coarse Sand (FM: 2.9-3.2)

Compiled by Md. Ashif Rayhan Shuvo, Lecturer, Department of CE, AUST

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Size of sand based on different codes:

Commonly based on grain size and soil consistency, several classification systems exist:
1. Unified Soil Classification System (USCS) (ASTM D2487-11).
2. American Association of State Highway and Transportation Officials (AASHTO)
(ASTM D3282-09).
3. U.S. Department of Agriculture (USDA).
4. Burmister Soil Identification System.
5. Massachusetts Institute of Technology (MIT).

Figure: Comparative size of sand, silt and clay

 Uses of Sand
 Principle component of concrete  Sandbags for protection against
 Brick manufacturing plants floods
 Sometimes mixed with paints  Railroads
 Used in landscaping  Plastering and mortar
 Glass manufacturing  Used for fill up the road & brick
soling gap area

 Desirable Properties of Sand

 Inert completely (i.e. should not have any chemical activity)
 Grains are sharp, strong and angular.
 Not contain hygroscopic salt (that attract atmospheric moisture i.e. CaCl2, MgCl2).
 Should not contain clay and silt, which are the harmful ingredients (usually 3-4% clay
and silt is ordinarily permitted for practical reasons)
 Free from organic matter.

Compiled by Md. Ashif Rayhan Shuvo, Lecturer, Department of CE, AUST

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 Tests for sand:

 Field Test-
Test for silt and clay:
If present in sand could be ascertained by determining the % loss in weight of a sample of
sand after washing the same with the aid of clean water.

However, field test can be performed by rubbing a small amount of sand between finger tips.
If clay spots are left on finger tips, it indicates the existence of clay in the considerable
amount. (See the explained procedure from the book of Dr. Latifee -page #208)

Test for Salt:

Can be tested by mixing the sand with fresh water and then test the water for salinity.

Test for organic matter:

Make 3% solution of NaOH and put some sand into the solution. Close the bottle for 24 hours
and meanwhile shake the solution vigorously. The color of the liquid turns brown if any
organic matter present in sand. The darkness of color gives the estimation of the amount of
organic matter exists in the sand.

 Substitute for Sand:

If good sand is not available in the nearby of the site, the substitutes may be used.

i) Stone screenings: Fine particles obtained by screening crushed stones. The grains are
sharp & strong, and hence impart better strength to the concrete if used.

ii) Surkhi: Obtained from finely powdered burnt clay. Also obtained by grinding slightly
under- burnt bricks. It disintegrates under the action of air and humidity. Not used for
external mortar. Used for lime mortar and lime concrete. It should be sufficiently fine to
pass through #8 US sieve.

 Bulking of Sand
It means increase in volume. Fine aggregate increase in volume when they possess some
moisture. It is due to formation of a thin film of water around sand particles. The thickness of
this film goes on increasing with more and more moisture. Therefore the increase in volume
of sand mass continues. This increase in volume varies 20% - 30% (volume basic) depending
upto fineness of sand. The finer will undergo with greater increase in volume. After a certain
% of water, the volume of sand decreasing with the further increase in water and eventually
the increased volume completely vanishes, and at this moment, the volume occupied by sand
becomes equal to the volume of sand.
Bulking of sand effects W/C ratio and also the proportioning of aggregate.

Compiled by Md. Ashif Rayhan Shuvo, Lecturer, Department of CE, AUST

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Figure: Bulking of sand

 Sieve Analysis and gradation

The particle size distribution of aggregate is called the grading.
Sieve analysis in a process in which an aggregate is separated into its various sizes by
passing it through screens of various size openings for the purpose of determining the
distribution of the quantities separated.
A Sieve is an apparatus- round or square in shape – with square openings, identified either by
the size of the opening or by a number.
US Standard Sieves For FA: # 4, 8, 16, 30, 50, 100 [4.75 mm, 2.36, 1.18, 0.6, 0.3, 0.15mm]
US Standard Sieves For CA: 3 in., 1.5 in., ¾ in., 3/8 in. [75 mm, 37.5mm, 19mm, 9.5 mm]

Compiled by Md. Ashif Rayhan Shuvo, Lecturer, Department of CE, AUST

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Commonly Used Sieve Sizes

Particle Size Distribution Curves

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Fineness Modulus
Using the sieve analysis results, a factor called the fineness modulus is often computed.
 This is a parameter for checking the uniformity of grading
 This is an index of fineness of an aggregate.
 The higher the FM, the coarser is the aggregate

It is computed by adding the cumulative percentage of aggregate retained on each of the

specific sieve s and divided the sum by 100.

Math: Sieve analysis, gradation curve and FM problem of sand is same as aggregate.

Example 1: The following is the result of the sieve analysis of two samples os and (1250gm
each), one from Savar and another from Durgapur. Calculate the combined fineness modulus.

Retained, gm Retained, gm
Sieve
(Savar Sand) (Durgapur Sand)
3″ 0 0
1.5″ 0 0
¾″ 0 0
3/8″ 0 0
#4 50 0
#8 150 50
#16 100 200
#30 350 150
#50 470 225
#100 30 625

Answer: Combined FM = 2.46

Example 2: Two sand samples has to be mixed to get a mixed sample of FM= 2.54. The
fineness modulus of the two individual samples is 2.84 & 2.24. Find the ratio in which the
samples have to be mixed to get the desired FM.

R1:R2 =

R2:RC =

Compiled by Md. Ashif Rayhan Shuvo, Lecturer, Department of CE, AUST