Table 10. Mold size and dimensions of tamping rods for the particle index test

Table 9. Results of particle index tests for various aggregates

Specific rugosity index

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Table 10. Mold size and dimensions of tamping rods for the particle index test. (After ASTM

D 3398-93.)

Aggregate

Aggregate size

specimen

Mold

Rod

Mass of

(mm)

Mold/Rod

size

diameter

height

diameter

length

rod

Passing Retained

designation

(kg)

(mm)

(g)

Huang (1965) modified the test method to

Bindra and Al-Sanad (1983) conducted tests on

measure the actual volume of the compacted

aggregates that ranged from natural aggregates to

aggregate mass. This involved a special device

blast furnace slags. They also looked at the effect of

called a volumeter, which fitted exactly over the

different gradations (open graded to dense graded)

mold. The volumeter was made up of a bottom

and concluded from their study that gradation did

thin flexible membrane and a standpipe. The pro-

not affect the weighted particle index value. It

cedure for compacting the sample remained the

should be noted that the gradation study included

same, except that at the end of the last layer, a

both the coarse and fine fractions. The weighted

flexible membrane was placed on top of the sur-

particle index for a given gradation is the weighted

face and water was poured through the stand-

mean of the percent retained in each sieve multi-

pipe to a prescribed height. The idea here is that

plied by the particle index for that size. The proce-

when water is introduced on top of the mem-

dure for determining the weighted particle index is

brane, the thin membrane will deform to match

presented in ASTM D 3398 (1996). Bindra and Al-

the surface. Knowing the volume of the mold and

Sanad (1983) also concluded from their study that

the volume of water in the volumeter, the actual

the particle index for smooth-surfaced, rounded

volume of the aggregate mass is calculated. Using

aggregates averaged around 6.5, and for crushed,

this method for volume measurement, more re-

high angularity, rough-textured aggregates, the av-

producible results were obtained (Huang 1965).

erage was around 17.5.

In addition to modifying the method for measur-

They also proposed a new method for calculat-

ing the volume of the compacted aggregates,

ing the volume of the aggregate mass in the mold.

Huang modified the test to determine particle in-

Instead of using the volumeter device developed

dex of fine aggregates (passing #4 and retained

by Huang (1965), they proposed a sand replace-

on the #200 sieve).

ment technique. This method involves placement

Bindra and Al-Sanad (1983) modified the par-

of a thin flexible membrane on top of the aggregate

ticle index test to test coarse aggregates up to 50-

surface. Sand (passing the #25 and retained on the

mm maximum size in their study. In this case,

#50 sieve) is then poured onto the surface of the

coarse aggregates are designated as any material

membrane to the top of the mold. The net weight of

larger than 2.36 mm (#8 sieve). The test method is

sand required to fill to the rim of the mold is ob-

similar to the procedure developed by Huang

tained and the volume to fill the mold is obtained.

(1965) with several exceptions. The mold used is

The volume of the compacted aggregate mass is the

cylindrical in shape and the dimensions and

difference between the volume of the mold and the

weight of the mold and tamping rod sizes are dif-

volume of sand required to fill the mold. This

method appears to be easier and less cumbersome

ferent. Details on the dimensions and weights of

than the volumeter method.

the mold and tamping rods are shown in Table 11.

Table 11. Dimensions of mold and tamping rods. (After

Bindra and Al-Sanad 1983.)

Inside

Diameter of

Length of

Weight of

Aggregate

diameter

height

tamping

size

of mold

rod

(mm)

(g)

2050

250.0

291.6

26.00

1045

4120

2.3620

152.4

177.8

15.88

610

930

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