Land Classification and Building Materials: A Comprehensive Study
Land Classification
According to Origin
- Sedimentary: Formed by the mixture of different organic materials, which depend on the rocks and weathering, and vegetation in different degrees of decomposition.
- Volcanic: Composed of minerals mixed with other materials from volcanic activity.
According to Response to Mechanical Action
- Incompressible: Under the action of loads not exceeding the limit of elasticity, they experience very low crushing and recover their position.
- Compressible: Under the action of loads, they experience crushing and do not recover their original position.
According to Construction Suitability
- Good Land: Formed by large banks of rocks, semi-rocks, gravel, or sand banks stranded between layers of tough terrain.
- Regular Land: Formed by resistant rock banks interrupted by faults, which cause discontinuities or changes in the rock mass.
- Bad Land: Consisting of wetlands, organic soils, landfills, etc.
According to NBE-AE-88
- Rocky Land: Solid formations with high compressive strength, classified into two groups:
- Isotropic Rocks: Cannot be stratified, such as granite.
- Stratified Rocks: Have a visible laminar stratification, such as slate.
- Cohesionless Greenfield: Mainly composed of aggregates or disintegrated rock, such as gravel, sand, and silt. These may contain a certain amount of clay, but without consistent cohesive bonding.
- Clay or Limestone Land: Formed by masses of clay or limestone, often containing disintegrated rock, resulting in land with enough resistance to compression.
- Difficult Land: Areas of the Earth’s crust consisting of wetlands, organic land, etc.
Building Materials
Pressure Bulbs
A foundation transmits loads to the ground, creating tension that gradually spreads. The imaginary lines limiting these tensions, according to the depth considered, form what is called a pressure bulb.
Main Minerals Forming Rocks
Quartz, feldspar, mica, tourmaline, talc, dolomite, calcite, pyrite, among others.
Clay When Fired
Clay loses its inhibition water at 400°C without undergoing any structural transformation. However, between 700°C and 800°C, it is no longer clay and becomes an aluminum silicate. At 1000°C, it becomes a very hard material with chemical stability, having begun a process of vitrification.
Marble
Marble is a metamorphic rock with a compact crystal texture, capable of a good polish.
Classification by Color
Unicolor, Polychrome, Streaked, Brecciated, Arborescent, or Fossiliferous (Lumaquela).
Classification by Use
Statuary, Architectural, Industrial.
Sedimentary Rocks
Sedimentary rocks are formed due to the Earth’s crust not being at rest but continually subject to different forces. The most frequently used in construction are clay, plaster, gravel, sand, etc.
Types of Sedimentary Rocks
- Mechanically Sedimented Rocks: Formed by fragments from the wreckage of other rocks. These fragments can be loose or disintegrated, joined by compression or bound by a natural cement.
- Organic or Biologically Loaded Rocks: Formed from the cementation and agglomeration of animal or plant remains, due to the effect of high temperatures and strong pressure.
- Chemically Sedimented Rocks: The wide variety of salts dissolved in the water of seas, lakes, and rivers are deposited by evaporation on the bottom, forming thick deposits. The most important chemically sedimented rocks used in construction are gypsum and limestone.