TO DETERMINE THE SPECIFIC GRAVITY AND ABSORPTION OF THE COARSE AGGREGATE

TO DETERMINE THE SPECIFIC GRAVITY AND ABSORPTION OF THE COARSE AGGREGATE

1.    EQPT/MATERIAL

            Weighing balance.Volumetric Flask of capacity 500ml, Conical mould mr.de from metal   sheet, base dia 3-l/2in top dia I-l/2in, height 2-7/Sin, tamping rod, sample of sand      (lOOOgms).

2.      PROCEDURE

a.       Take approximate 500 grams of sand sample in a pan and dry it in oven to constant weight.

b.      Cover the sample with distilled water and let it stay immerse for 24 hours.

c.       After 24 hours decant the water and spread the sample on a Hat smooth surface,

d.      Expose the sample to a gentle current of warm air. Take S.S.D weight.

e.       Fine aggregate is then packed loosely in the conical mould, the surface lightly tamped 25 times with the tamping rod and mould lifted vertically up. If free moisture is present then the cone of time aggregate will retain its shape.

f.        Drying with constant stirring is continued and the test made at frequent, interval until the

            cone of fine aggregate slumps upon removal of the mould.

g.       This stage indicates that fine aggregate has reached a surface dry condition,

h.       Now take approx 500 grams sample prepared above and introduce it into the volumetric

            flask. Fill it to 500ml mark with water at 20 °C.

i.        Roll the flask on a flat surface to remove air bubbles. After this keep the flask at 20 °C in

            oven for one hour then fill it upto 500ml mark and weigh it. 

j.        Now remove fine aggregate horn flask, dry it in oven to a constant weight, allow it to cool to room temperature and weigh.

3.    Precautions

a.       Take all the weights with care.

b.      Roll the flask gently.

4.      The Performa/Format for the prep with the record of obsns, data, with the notes to helps its completion.  

S/No	Bulk Spec Gr. S.S.D	Bulk Spec Gr. Oven dried	Absorption %
1.	A/A =C-D	B/A = C-D	(A-B/B) 100
2.

1.      Interpretation/collection of the obsn readings, graphs, etc leading to results.

            To be done with standard specification of ASTM standard C 128

2.      Comments

1.      Specific gravity of SSD is 2.7

2.      Apparent specific gravity is 2.86

3.      Absorption of F.A is 1.6%