Soil inspection is one of the most important yet often neglected steps in a construction process. Often, contractors will simply start working on a post or foundation and call it good. However, soils often have hidden characteristics that can lead to expensive problems down the road if you do not identify and deal with them properly. Different types of soil testing methods exist to help contractors and engineers assess soil properties.
In this blog, Graana.com, Pakistan’s smartest property portal, has discussed different types of soil testing done in construction.
What Is Soil Testing in Construction?
Soil testing is a process of determining the soil’s physical and chemical properties. Particularly, it is used in the construction industry to determine the type of foundation for a structure.
Types of soil testing in construction
Discussed below are the most common types of soil tests in construction.
Moisture Content Test
A moisture content test is a way to measure the amount of water in a substance. There are many different ways to do this, but all of them rely on the principle that water has a higher boiling point than most other substances.
By measuring the temperature at which a substance boils, it is possible to calculate the percentage of water in that substance.
The oven-drying method, calcium carbide method, torsion balance method, pycnometer method, sand bath method, radiation method, and alcohol method are all used to determine the moisture content of the soil.
Amongst all, the oven-drying method is the most popular approach; it involves weighing the sample soil, drying it in an oven at 110 degrees Celsius (+/- 5 degrees), and then weighing it again.
The water weight in the soil is represented by the difference between the before and after weights.
Atterberg Limit Test
This is another type of soil testing in construction. The Atterberg Limits are a series of moisture content tests on cohesive soils that can indicate soil plasticity.
The test helps classify soil and its plasticity characteristics, as well as evaluate near-surface soil shrink/swell potential. You can use it to identify different types of silt and clay, as well as assess the soil sample’s shrinkage limit (SL), plastic limit (PL), and liquid limit (LL).
Moreover, you must perform this test on a soil sample that has been dried in an oven at 105 °C for 24 hours. Following, crush the soil to a fine powder and pass it through a 2 mm sieve.
Place a small quantity (about 1 g) of the soil in a container, and add the water.
Furthermore, The moisture content of clay soil affects its firmness and behaviour. The behaviour of the soil sample determines the limit at which the change occurs.
The soil can be in one of four states, depending on the moisture content:
- Semi-solid
- Solid
- Liquid
- Plastic
Specific Gravity Test
The specific gravity test is a common procedure that you can use for soil testing in construction to determine the moisture content of the soil. It is based on the principle that the weight of a volume of material is directly proportional to the weight of an equal volume of water.
This property is known as density, and you can use it to measure the moisture content of soil by comparing its densities to that of pure water. By definition, the specific gravity of a substance is the ratio of its density to the density of pure water at 4 degrees Celsius.
The density bottle method, Pycnometer method, gas jar method, shrinkage limit method, and measurement flask method are some of the methods that you can use to determine it. Amongst these, the pycnometer methods and density bottle are used most often for soil analysis.
Proctor’s Compaction Test
Proctor’s compaction test is a basic soil testing procedure used to determine a soil specimen’s compressive strength. The test results can indicate the type of foundation on which a structure should be built, as well as predict the maximum load that it can support.
The Proctor’s compression test is widely accepted and easy to perform, making it an ideal option for field testing.
You can carry out the test procedure by compacting dry soil specimens in a metal container using a compaction hammer. You can use it to determine the soil’s compaction properties. After air-drying, you will have to separate the soil sample into four to six smaller samples.
Afterward, add water to alter their water content, ranging from 3% to 5%. Finally, they arrange samples in three layers in the Proctor compaction mold. You can then use a normal 5.5-pound hammer to strike each layer 25 times. Get to know how to improve bearing capacity of soil?
Dry Density Test
The dry density test is one of the most popular and commonly used tests for determining the unit weight or density of soils. It is also called the nuclear gauge method.
In this test, a nuclear gauge is calibrated with reference to water and then used to measure the dry density of soil.
A dry density test in the soil is carried out at 2 levels:
Core Cutter Method
The soil is extracted from the ground using a typical cylindrical core cutter, and the sample is weighed for testing. The sample’s water content is determined, and the dry density is calculated.
Sand Replacement Method
This level involves excavating a hole and measuring the soil’s dry density with it. Firstly, fill the hole with dry sand that is homogeneous in density.
Afterward, calculate the volume of the hole by dividing the mass of sand poured into the hole by the dry density of sand.
Importance of Soil Testing in Construction
Certainly, soil testing is an important part of any construction project as you can determine its composition and characteristics. This information is essential for designing a safe and stable foundation.
There are many other factors that signify the importance of soil testing in construction:
- Used in civil engineering and construction to determine soil suitability for a particular purpose
- Used to assess the impact of construction on the soil
- Helps to determine the type and quantity of soil required for a project
- Helps assess construction’s impact on soil and identify any potential problems
- Aid to determine soil suitability for specific applications, such as pavements or foundations
So, these are some of the major types of soil testing in construction that you need to know about. To read more about the construction sector of Pakistan, visit our blog.
