1. Objective
The objective of this lab is to be familiar with testing the some specific requirements of
aggregates which are gradation, bulk density, specific gravity and absorption.
2. Introduction
Aggregates are very useful and frequently material for civil and building engineering; it is a
manufactured and recycled material. Aggregate can be natural sand, gravel pits, and river
rock which are crushed. In general, aggregates are produced from quarry through crushing
processes; it is used on foundations and pavements. The requirement tests are so important
for sample collection and quality checking before applying on the pavement or foundation
construction.
One of the testing object is aggregates’ gradation, which is to make sure the aggregate
particle have the properly size of distribution. Aggregates are divided into coarse aggregates,
fine aggregates and mineral fillers according to their sizes. The size distribution as one of the
most important quality of aggregate related with hot mix asphalt. The allowable gradation is
generally designed for controlling asphalt concrete mixture. In one words, these requirements
are trying to make sure aggregate’s permeability and workability. Generally for civil
engineering people, they use a sieve to analysis aggregates’ size distribution.
Bulk density of aggregates is “the mass of one unit volume of bulk aggregate material”
(ASTM C29). The higher bulk density can be well filled with fine aggregates and cement to
check the degree of compaction (Afsar, 2012). Specific gravity generally defined as the ratio
of aggregates divided by an equal volume of water; it can’t identified the quality of
aggregates, but it can control the concrete mixture design.
Absorption and surface moisture of aggregates is to control the water content when design
Portland cement concrete. Surface moisture appear in aggregate voids which can’t improve
the workability of concrete, but it can indirectly affect the water content to mix with concrete.
Figure-1 is showing the moisture conditions of aggregates according to the absorption of
aggregates. Different states indicates different moisture in the surface of aggregates.
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Figure-1: Moisture conditions of aggregates (David and Heiserman, 2015)
3. Procedures
All tests carried out according to ASTM C136, ASTM C29, ASTM C127, which are the
standards of aggregate and coarse aggregate.
Fine aggregate-Sieve Analysis
In this experiment, this gradation test is to determine the size distribution of aggregates,
equipment and materials using include: sieves, digital balance, sieve shaker, and fine
aggregate (dry).
Using approximately 500 g of dried aggregates as a testing sample. Weighting every layers of
empty sieve and recording its mass on data sheet. Arranging the largest sieves on top and pan
at bottom orderly. Taking the testing sample on the top sieve and placing the whole sieve in a
sieve shaker. After shaking around 10 mins, turn off the machine and take out the whole
sieve. Weighting every sieve again and record the mass on sheet paper.
Bulk Density-Coarse Aggregate
In this experiment, the Bulk density test is to calculate the mass divided the volume of
aggregates. The equipment and material includes: digital balance, tamping rod
(Diameter=16mm), bulk density measure and coarse aggregate (dry).
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Putting the measure on the balance and zero the scale. The initial mass of empty measure
record as zero which is T. Then filling with water and recording the mass of water, W.
Measuring the temperature of the water. Empty the measure and dry it. Start to fill the
measure with the coarse aggregate. Step by step to fill the measure, first fill 1/3 of the
measure and rod 25 times frequently. Repeating the last mentioning steps for next two 1/3.
The measure is filled with the coarse aggregate properly, which it should become small
projecting aggregate particles. Last step to determine the mass of measure with full small
particles of aggregates, G.
Specific Gravity and Absorption
In this experiment, the specific gravity and absorption test is to get over the voids content,
oven-day specific gravity and SSD specific gravity. The equipment and material includes:
