1.3 Classification tests

1.1.3 Determination of natural moisture content and Atterberg limits

Water Content and Atterberg Limits
The moisture content determination test is of particular importance for cohesive soils (clay silt soil), the strength of their bearing is directly proportional to the moisture content, and the rebound properties of clay soils or the collapse properties of sandy soils largely depend on the natural moisture content.
The atterberg boundary test (fluidity and plasticity limit) plays an essential role in the classification of clay silt soil, as there are approximate relationships between the natural moisture content and the atterberg boundary and the geometric characteristics of the soil such as the permissible soil stress and the coefficient of soil cohesion.

2-1-3 Grain Size distribution (Sieve analysis and Hydrometer)

The granular gradient test includes two types of tests, namely:
Sieve analysis test, which is specific for Sandy and/or humus soils, and a hydrometer test that determines the granular gradient clay silt soil. This test is important in classifying the soil and determining its natural components, as well as in identifying the soil permeability coefficient, which is considered the most important variable in ground dewatering works.

3-1-3 free Swell

This test is carried out on any of the different types of soil to find out its susceptibility to swelling or not. Based on the results of this simple initial test, the soil can be classified on the basis that it is susceptible to swelling or not. The results of this test are also a guide for more complex tests (such as the bulge pressure determination test).

2.3 Tests to determine the different geometric characteristics of the soil

1-2-3 Consolidation Test

This test directly determines various variables (such as Void Ratio, Compression Index, Pre-consolidation Pressure, Over Consolidation Ratio) by which it is possible to determine the expected consolidation values of clay silt soil when exposed to loads of a building. The institute has two types of devices for conducting this test: manually operated devices and other digital & Computerized devices.

2-3-2 swelling Pressure.

This test identifies several important variables for swelling soil such as swelling stress, swelling energy and soil swelling ratio. The swelling pressure of the soil is a central factor regarding how the foundation is laid, the choice of the type of foundation and the development of the necessary precautions to prevent problems for the building.

3-2- collapsible Potential test

Collapsible soils are one of the most dangerous types of soils that affect buildings. Consequently, determining the various variants of this type of soil and with high accuracy is a direct cause for the safety of a building. This test is carried out on previous reinforcement devices with a difference in the method of processing and conducting the test, since the collapse energy and the amount of instantaneous collapse occurring in the soil can be measured in a direct way. From the results of this test, it is possible to develop the necessary recommendations to overcome the problems of this type of soil on the site and protect the building from the danger of constructing foundations on this type of soil.

4-2-3 direct Shear Box test

This test is considered one of the most important tests in determining the basic soil variables (Angle of shearing Resistance and Cohesion Factor, Φ & C), which are used to calculate the bearing capacity of soil in resisting all forms of different loads, whether vertical loads (such as surface foundations), pile loads or horizontal. Also, through these advanced devices, it is possible to determine (Φ & C) under dynamic loads by performing Cyclic Loading Test on the sample, where these results are useful in calculations for earthquakes, or structures exposed to certain vibrations.

5-2-3 triaxial pressure test

This test is considered one of the most accurate tests in determining (C & Φ modulus of elasticity E) for all soil types. The sample is tested under the same natural conditions (surrounding stresses) (Boundary Conditions), which gives the results great credibility.
The institute has two types of devices to conduct this test, one of which is manually operated device (sample installation, load setting, and taking readings), and other digital & Computerized device where the device after placing the sample in it and adjusting the program to conduct the test from start to finish. Noting that the duration of this test ranges from several hours to several days depending on the type of test in terms of allowing the disposal of water from the sample, such as:
Unconsolidated Undrained – Consolidated Undrained or Consolidated Drained