HOW TO TEST AGGREGATE FOR BULK DENSITY AND VOIDS?

Objective

Determination of unit weight or bulk density and zero of the aggregate.

devices

Name Capacity
1. Balance Sensitive to 0.5% of material weight
2. Cylindrical Metal Measurement 3 liters of capacity (exactly for total)

15 liters of capacity (up to 40 mm in total)

3. Tamping Rod 16 mm diameter. and 60 cm tall
Cylindrical metal measurements used for void testing of bulk density and aggregate
Cylindrical metal measurements used for void testing of bulk density and aggregate

Sample preparation

  • Take the required amount of test sample using any sample reduction method.
  • Testing is usually performed on dry materials, but when bulk testing is required, materials with a given percentage of moisture may be used.

a. Process for Compressed Bulk Density

  1. Measure the volume of the cylindrical metal measure by adding water to the metal measure and record the volume “V” in liters.
  2. Fill the cylindrical metal measure approximately one-third full with the mixed aggregate and tamp it 25 times using a tamping bar.
  3. Add another layer of one third of the total to the metal measure and give 25 strokes of the tamping bar.
  4. Finally fill the over-flowing total in the metal measurement and tamp it 25 times.
  5. Remove surplus aggregates using a tamping rod as a straightedge.
  6. Determine the weight of the total in the measurement and record that weight “W” in kg.

Calculations for Compressed Bulk Density

Compressed Unit Weight or Bulk Density = W/V

Where,

W = Weight of the aggregate held in the cylindrical metal measure, kg

V = Volume of the cylindrical metal measure, liters

Calculation of voids

The percentage of vacancies is calculated as follows

Percentage of Vacancies = [(G – ϒ)/G]*100

Where


g = specific gravity of the aggregate

= bulk density kg/litre. In

B. Process for Loose Bulk Density

  1. Measure the volume of the cylindrical metal measure by adding water to the metal measure and record the volume “V” in liters.
  2. Fill the cylindrical measurement to overflow by means of a shovel or scoop, being discharged from a height of not more than 5 cm from the top of the measurement
  3. Level the top surface of the aggregate with a straightedge or tamping bar in the metal measure.
  4. Determine the weight of the total in the measurement and record the weight “W” in kg.

Calculations for Loose Bulk Density

Loose Unit Weight or Bulk Density = W/V


Where,

W = Weight of loose aggregate in cylindrical metal measurement, kg

V = Volume of the cylindrical metal measure, liters

Calculation of voids

The percentage of vacancies is calculated as follows

Percentage of Vacancies = [(G – ϒ)/G]*100


Where

g = specific gravity of the aggregate

= bulk density kg/litre. In

result

The bulk density is rounded off to the nearest 0.01 kg in kg/l. have been informed in

The percentage of vacancies are reported to the nearest whole number.


mention whether the set is

(a) oven dry,

(b) saturated and surface dry or


(c) with a given percentage of moisture.


Er. Mukesh Kumar

Photo of author
Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.