OBJECT:To Determine The Loose And Compacted Bulk Density And %Age Of Voids Of Fine And Coarse Aggregate

OBJECT:To Determine The Loose And Compacted Bulk Density And %Age Of Voids Of Fine And Coarse Aggregate

STANDARD:

ASTM C-29, IS Code 2386 part 3, AASHTO T19

APPARATUS:

• 
   Weighing Balance
  
• 
   Temping Rod
  
• 
   Measuring Cylinder
  
• 
   Shovel or stool
  

SCOPE AND SIGNIFICANCE:

This method is used to determine the bulk density of given specimen during the concrete mix design when the aggregate is to be batched by volume or by weight. Then it is necessary to know the mass of the aggregate that will fill the container of unit volume.

If we know the bulk density of aggregate material than we can easily calculate the mass required to fill a unit volume container.

Bulk Density also indicates the %age of voids present in the aggregate material.

This %age of voids effects the grading of the aggregate which is important in higher strength concrete.

RELATED THEORY:

Bulk Density:

It is the mass of the unit volume of bulk aggregate material.(Aggregates +Voids)

The term volume includes the volume of the individual particle and the volume of the voids between the particles.

Bulk density is used in weight and volume batching both.

Absolute Density:

It is the mass per unit volume of individual particles only.

Voids:

It is a space between the individual particles and in a unit volume of the aggregate mass and is not occupied by the solid mineral matters.

Voids within the particles are not included in the voids for the determination of bulk density by this method

Facts about Bulk Density:

Bulk Density depends upon how densely the aggregate is packed.

It also depends upon the size, distribution and shape of the particles.

If particles are of the same size then it can be packed to a limited extent but when the smaller

particles are added, the voids get filled with them and thus the bulk density increases.

For a coarse aggregate a higher bulk density means that there are few voids which are to be filled by the fine aggregate and cement thus the bulk density also depend upon the degree of packed.

PROCEDURE:

1. 
   Weigh the empty cylinder
   
2. 
    Calculate the volume of the empty cylinder.
   
3. 
    Take the weight of cylinder with loose aggregate
   
4. 
   . Take the weight of cylinder with compacted aggregate(compaction in three layers with 25 number of blows.
   

*The Procedure will be same for fine and coarse aggregate.

Specific Gravity of C.aggregate=2.65

Specific Gravity of F.aggregate=2.75

Loose Bulk Density

Compact Density

OBSERVATIONS AND CALCULATIONS:

Table of observations for Bulk Density

REVIEW QUESTIONS:

1.why it is important to know the bulk density of aggregates?

2.what is the relation between bulk density and size of aggregates? Mention any two application of bulk density.