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.
- Original rock name and group name
- particle size
- 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.
- need for cement
Aggregates are available in many different sizes. Use the following table to find out what size the set corresponds to.
|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.
|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|