EXPERIMENT NO-7

AIM: Sieve analysis of the given sample of coarse aggregate and determine the fineness modulus.
THEORY:

Coarse aggregate is the broken stone used in concrete .The coarse aggregate unless mixed with fine aggregate serves no purpose in cement works .the size of fine aggregate is limited to a maximum of 4.75 mm gauge beyond which it is known as coarse aggregate .

FINENESS MODULUS:

Fineness modulus is only a numerical index of fineness, giving some idea of the mean size of the particle s in the entire body of the aggregate. To a certain extent it is a method of standardization of the grading of the aggregate. It is obtained by adding the percentage weight of material retained in each of the standard sieves and dividing it by 100.

To object of finding the fineness modulus is to grade a given aggregate for the most economical mix and workability with minimum quantity of cement .Certain limits of fineness modulus for fine coarseaggregates are given in the table below and a sample under test should satisfy these results so that the aggregate may give good workability under economical conditions.

LIMIT OF FINENESS MODULUS

Maximum size of aggregate	Fineness modulus
	Minimum	Maximum
Fine Aggregate	2	3.5
Coarse aggregate 20mm	6	6.9
Coarse aggregate 40mm	6.9	7.5
Coarse aggregate 75mm	7.5	8.0

If the test aggregate gives higher fineness modulus the mix will be harsh and if on the other hand gives a lower fineness modulus it gives uneconomical mix .

APPARATUS:

Indian standard test sieves, weighing balance ,sieve shaker etc .

Size of sieves to be used.

(II) For coarse aggregate-25mm,20mm 12.5mm, 10mm, 4.75mm.

PROCEDURE

COARSE AGGREGATES

(i)Take one kg of coarse aggregate

(ii)Arrange the sieves one over the other in relation to their size of opening.(25mm,20mm,12.5mm10mm,4.75mm)

(iii) Carry out the sieving for the specified time

(iv) Find the weight of agggregate retained on each sieve taken in order and tabulate in table.

GRAPH

Draw a graph with sieve opening to log scale on the X-axis and % finer on Y-axis .The curve iscalled a grading curve.

CALCULATION

COARSEAGGREGATE

3. Fineness modulus (Sum of cumulative % wt retained /100) =

RESULT S

COARSE AGGREGATES

 Fineness modulus =