BUILDING CONSTRUCTION & MATERIALS : Stone Part-E

Using Different Methods for Grading of Aggregates 

Grading of aggregates consists of balancing the excellent and the coarse aggregates in such a ratio, with a view to obtain the most powerful and densest combination with the least quantity of cement. Grading the aggregates is so graded as to have minimal voids while combined with all ingredients, and water need to render a concrete mass of smooth work-ability.

Following methods are done the grading of aggregates

1. By trail 

2. By finesse modules method (sieve analysis method)

3. By minimum voids method

4. By arbitrary standards

a).By trail

In this method, proportioning of aggregates to provide heaviest weight for identical volume yields the densest concrete.

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b).By finesse modules method (sieve analysis method)

In this process, the samples of each coarse and satisfactory aggregates are exceeded via a sequence of 9 well-known sieves, and the share of the pattern retained on every of these sieves is determined. The sum divided with the aid of using one hundred of those possibilities offers a pattern modulus of finesses.

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c).By minimum voids method

 This technique is primarily based totally on the fact that to gain dense concrete the quantity of cement must additionally be slightly in excess of voids greater than the fine aggregates. In this technique the voids with-inside the fine and coarse aggregates are separately determined out with the assist of graduated cylinder and water. The percentage of voids I  aggregate, “X” given through the equation.

X = (V1 – V2) x 100/V2

Where V1, volume of water filled

Where V2, volume of aggregates.

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d). By arbitrary standards

It is a usually followed technique of propitiating the aggregates in a concrete blend for small works of slight importance. This technique is not encouraged for big works or vital works. In this technique, the quantity of cement, sand and coarse aggregates are taken in the percentage of 1:n:2n respectively. The amount of water to be used varies suit the work-ability described.

1:1:2 M250 rich mix for beams & columns etc

1:1:3 – M200 Water retaining structures etc

1:3:6 – M150 columns,slab,roads etc

1:3:6 – M100 – foundations,

1:4:8 - For mass concrete.

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REFERENCE BOOKS

1. BUILDING MATERIAL - RANGAWALA 2. BUILDING MATERIAL - SUSHIL KUMAR 3. BUILDING MATERIALS & CONSTRUCTION - B.P.BINDRA 4. BUILDING CONSTRUCTION - B.C.RANGWALA 5. BUILDING MATERIALS - A.KAMALA 6. BUILDING CONSTRUCTION & MATERIALS

-MR. SHRIKANT D. BOBADE