When inspecting aggregate for quality control purpose, it is necessary to describe its physical properties, as the physical properties of aggregate have an effect on the property of concrete. The physical properties of aggregates that should be described are given below.

  1. Original rock name and group name
  2. particle size
  3. surface texture

Let us see how to describe the above properties of sets.

physical characteristics of the aggregate

1. Parent’s name Rock and group name

All aggregates arise due to the dissolution of rocks. Due to this the property of the aggregate is equal to the property of its parent rock. If we can know the name of the parent rock then we can certainly get some facts about its power properties. But this doesn’t always happen. Sometimes the properties of the aggregate are completely different from that of the parent rock.

On the basis of origin there are 3 primary types of rocks, viz.

  • igneous rock
  • sedimentary stone
  • metamorphic rock

Click here to learn more about these rock types

We can take the help of a professional geologist to know the name of the parent rock.

After identifying the name of the parent rock, the next step is to place it under some trade group. Below are some trade group names for the different types of parent rocks.

parent rock business group Example
igneous rock granite group granite, granite, diorite, cyanite
igneous rock Gabro Group gabbro, norite, peridotite
igneous rock applite group Aplite, Porphyry
igneous rock dolerite group dolerite, lamprofire
igneous rock rhyolite group rhyolite, tracheite, felsite
igneous rock basalt group Andesite, Basalty
sedimentary stone sandstone group sandstone, quartzite, grit
sedimentary stone limestone group limestone, dolmite
metamorphic rock ganuleite and gneiss group ganite gneiss, amphibole, granulite
metamorphic rock schist group slate, schisto
metamorphic rock marble group marble, crystalline limestone

2. Particle Size

The size of the aggregate is an important characteristic of the aggregate, as it affects the following properties of concrete.

  • feasibility
  • Strength
  • need for cement

Aggregates are available in many different sizes. Use the following table to find out what size the set corresponds to.

angular set
angular set
flaky aggregates and elongated aggregates
flaky aggregates and elongated aggregates
irregular set
irregular set
round aggregate (gravel)
round aggregate (gravel)
particle size Description Example
Round completely water-worn, or completely shaped by attrition gravel on the banks of a river or sea; desert and beach sand
irregular or partially rounded naturally irregular or partially shaped by attrition, with rounded edges pit sand and gravel; land or dug flint; cuboidal rock
Angular Having well defined edges formed at the intersection of roughly flat faces all kinds of crushed rocks
flaky Thickness is small relative to width and/or length crumbling rocks
long The length is much larger than the other two dimensions crushed rocks
flaky and long Material whose length is much greater than the breadth and the width is greater than the thickness Crushed Rocks, Crushed Rocks

3. Surface Texture

In concrete, the bone between the aggregate and the cement paste is largely influenced by the surface texture of the aggregate. Aggregates with a rough surface texture will have a better bond than a smooth surface.

By a thorough visual inspection, we can describe its surface texture. Use the following table to describe the aggregate for its surface texture.

surface texture Description Example
Lifeless making the surface shiny and non-porous black flint
seamless wear and tear gravel, chert, slate, marble
finely more or less round granular fracture sandstone
rough rough fracture or fine or medium grained rocks that do not have readily visible crystalline components basalt, felsites, limestone
crystalline containing easily visible crystalline components granite, gabbro, dolomite
honey comb and porous with visible pores and pores brick, pumice stone

Er. Mukesh Kumar

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Er. Mukesh Kumar is Editor in Chief and Co-Funder at 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.