There are many things to consider before any residential construction such as the type of building or structure to be erected, the materials to be used, the labor to be employed, and very important, the soil on which the construction will be done.
Soil testing is a crucial procedure in construction that is used to assess the suitability and strength of the soil to support a building. It is done to assess the quality of the soil and ultimately to avoid any future damage to the building. Do not however mistake this for soil testing in agriculture which is used to measure the pH level and nutrient deficiencies in a particular soil.
Since soil is affected by several factors such as weather and climate change it is important to check the soil health before commencing work. It is also important to consider the previous work that was done on the land, like farming, or previous construction.
Soil testing gives constructors an idea of what to expect when building on soil. But, is it really necessary to do soil testing, and is it as important as experts claim? Let’s find out.
Why Is Soil Testing Done?
Soil is made up of several chemical, biological, and physical components. These soil components all interact to affect the soil stability and bearing capacity. Some of the reasons why soil testing is done are;
1. To determine the soil quality and suitability
Experts perform soil testing to determine whether the soil is of good quality and if it is suitable for a project. Construction projects may be delayed or even canceled because of soil unsuitability.
2. To determine the water level
It helps them to determine the water level of the soil, and with this information, they can make the best decision as to the type of building materials that suits the nature of the soil.
3. To identify engineering properties of the soil
The engineering properties of soil can greatly affect its quality and suitability for the construction of any structure. One of these properties is the specific gravity of the soil, some others being elasticity, permeability, and cohesion. It is very important to determine the engineering properties of the soil on your site as it gives an insight into what to expect.
How Is Soil Testing Done?
There are different types of soil tests, and they are all done differently. These tests can be categorized according to what they are expected to reveal and also on the properties of the soil. They can be conducted either in a laboratory or on the construction site.
1. Moisture Content Test
The moisture content of soil can greatly affect major decisions in construction. For example, the moisture content of the soil will determine whether to use corrosion-resistant materials instead of regular ones.
Therefore, it is important to carry out this test before construction. The methods for this test include but are not limited to, the oven-drying method, torsion balance method, alcohol method, and the sand bath method.
2. Gravity Test
This test can be done using different methods such as the density bottle method, the shrinkage limit method, and the Pycnometer method. The test determines the ratio of the density of the soil solids to the density of the water.
3. Dry Density Test
The dry density test helps to determine whether the soil is dense or loose depending on the weight of the soil particles. It can be done using the water replacement method, the core cutter, or the sand replacement method.
There are other types of tests like the Atterberg Limits test which measures the critical water content of fine-grained soil using three limits; the liquid limit test which uses Casagrande’s liquid limit device to determine the soil’s liquid limit, the plastic limit test, and the shrinkage limit test.
In the plastic limit test, water is added to the soil sample, it is then put into a glass plate and rolled into threads. The idea behind this method is to test the point at which the thread breaks as a new sample is used, each with less water than the previous one.
While in the shrinkage limit test, a formula is used to determine the amount of water that will fill the voids of the soil. There is also the Proctor’s Compaction test to determine the compaction in the soil by reducing the air voids.
What It Generally Costs To Do A Soil Test
The cost of having a soil test depends on several factors, such as the type of test that will be done and the company that is hired to perform the test. These companies differ based on the accuracy of their services and the price that they charge.
Generally, it costs about $390 to $490 to perform the Soil test in Australia. The price may increase depending on the proposed type of construction, and the depth of drilling that will be done. Sites with the deep filling will cost more since they require deeper drilling.
In case there is concrete paving it will cost additional fees to cut the concrete. Additional testing may attract additional fees.
Also if your site falls within a designated Erosion Management Overlay (EMO), or outside a normal residential setting you may be charged more. Some companies also charge travel fees, if your site is located in another country.
Generally, the cost is totally dependent on the project, the depth of testing required, the contractors hired, and the site requirements.
Soil testing is an efficient way to assess the quality of the soil. Although it is not a relatively cheap procedure because of all the possible expenses that may bTe faced, soil testing can help to prevent future troubles with your building and thus, save you the cost of repairs.
So it is preferable to have a soil test done on your site before you start building. Whether the soil testing is done on-site or in a laboratory, ensure that the specialists involved are qualified so you can get value for your money.
The time it takes for the test to be completed is dependent on the parameter being measured and possible unforeseen delays which may be encountered.