What are flaky and elongated aggregates? How can the shape of aggregate influence strength of concrete? Following is the result of a sieve analysis of 500 gm aggregate:
IS sieve size | 10 mm | 4.75 mm | 2·36 mm | 1·18 mm | 600 micron | 300 micron | 150 micron | lower than 150 micron |
Weight retained in gm | 0 | 10 | 50 | 50 | 95 | 175 | 85 | 35 |
Find out the 'Fineness Modulus' of the sample
FLAKY AGGREGATES:- This agg. Are those whose least dimension i.e. thickness is less than 3/5 th of their mean dimension.
ELONGATED AGGREGATES:- This agg. are those whose greater dimension i.e. length is greater than 9/5 th of their mean dimension.
According to shape voids
Rounded aggregate 32 – 33 %
Irregular aggregate 35 – 38 %
Angular aggregate 38 – 40 %
Rounded aggregate gives better workability and Angular aggregate gives better strength.
total wt. = 500gm.
Sieve | Wt. retained in each sieve(gm) | % wt. retained | cumulative % of wt. retained | % finer |
10 mm | 0 | 0 | 0 | 100 |
4.75 mm | 10 | 2 | 2 | 98 |
2.36 mm | 50 | 10 | 12 | 88 |
1.18 mm | 50 | 10 | 22 | 78 |
600 µ | 95 | 19 | 41 | 59 |
300 µ | 175 | 35 | 76 | 24 |
150 µ | 85 | 17 | 93 | 07 |
<150 µ | 35 | 7 | 100 | 00 |
Ƹ = 346 |
So, F.M. = 346/100 = 3.46
F.M. of coarse aggregate is3.46.
What is an air entraining agents? Give some examples. What is efflorescence in concrete structure?
What are flaky and elongated aggregates? How can the shape of aggregate influence strength of concrete? Following is the result of a sieve analysis of 500 gm aggregate:
IS sieve size | 10 mm | 4.75 mm | 2·36 mm | 1·18 mm | 600 micron | 300 micron | 150 micron | lower than 150 micron |
Weight retained in gm | 0 | 10 | 50 | 50 | 95 | 175 | 85 | 35 |
Find out the 'Fineness Modulus' of the sample