Laboratory Testing Systems
Determination of Unit Volume Weights:
The first and important index property of the soils; It is the unit volume weight value of the ground. The unit volume weight can be calculated from different species such as natural, dry, saturated, sunken and grain depending on the condition of the ground.
Determination of Specific Weights:
Specific gravity (Gs) is defined as the ratio of the weight per unit volume of water to the volume per unit weight of water. For the determination of the specific gravity, glass bottles called jars of 1 lt are used for coarse-grained soils and more bulky (50-100 cm 3) pycnometers are used for fine-grained soils.
Determination of Water Content:
Water content (w) is a term that reflects the water condition it contains in the intergranular spaces and is expressed as the ratio of water weight to dry weight. The experiment is carried out on fine-grained soils and coarse-grained soils on different amounts of samples.
Sieve Analysis:
Determination of particle size of soils, classification of soils, determination of uniformity and grading coefficients, selection of core and filter materials in dams, etc. It is important. In addition, determination of the percentage amounts of grains (gravel, sand, silt, clay) on a ground; It also provides important information about other engineering properties of the soil. These features; density, hydraulic conductivity, water retention properties, resistance / strength properties, etc. d. The analyzes made to determine the grain sizes of any soil material and the weight ratios of the grains of this different size are called “sieve analyzes ve and the soil classification is made for different purposes.
Determination of Atterberg Limits (Liquid Limit-Plastic Limit- Shrinkage Limit):
The behavior of soils depending on the water content was described experimentally by Atterberg in 1911. The boundary water contents defined by Atterberg are called Attarberg boundaries or consistency classes. The consistency of the soil (Atterberg) limits the water content in which cohesive soils are present in certain physical conditions and if it is evaluated well, many properties of the soils can be learned.
Sand Cone Test:
Sand cone method ’is the method frequently used to determine the density of soils in situ. The sand cone method is used to determine the soil density in the field and to control the land compaction results of the fillings such as soil filling and road filling. In sand cone method; The weight of the excavated site is determined. The volume of the pit is then determined by filling it with sand of known density. With this method, unit volume weight and dry unit volume weights can be calculated in situ.
Standard Proctor:
In order to increase the carrying capacity of soils, to reduce settling under constant moving and dynamic loads, and to prevent the formation of volumetric changes by taking more water by decreasing the permeability of soils, laying the soils in layers and compressing the air and soil grains while the water and grain volume is constant by means of mechanical means. is called compaction. In a compacted substrate, the degree of compaction is the dry unit volume weight of that substrate. The larger the dry unit volume weight, the better the floor is compacted. Proctor (1933) When a soil is compressed with a constant compaction energy at different water contents, the dry unit volume weight increases, reaches a maximum value and then decreases due to the increased water content. The water content in which the dry unit volume weight is maximum is called the optimum water content. Since the best compaction is achieved at the optimum water content, field compaction; should be made by ensuring that the ground to be compacted has an optimum water content. The optimum water content of a soil is determined by a proctor test in the laboratory.
CBR Test
The California Transport Ratio (CBR) is a relative measure of the shear strength of the ground and determines the behavior of granular layers for superstructures. In other words: the relative carrying value of the foundation, subbase and natural soil is expressed by CBR. This test is carried out by measuring the load required to allow a cylindrical piston of a standard size of 50 mm in diameter to sink into the soil sample at a certain speed and to determine the load-penetration relationship. This load is divided by the load required for the plunger to sink to the same depth in a standard crushed stone sample, and the result is the percentage expression CBR. That is, the bearing capacity of the ground is expressed in terms of the bearing capacity of the reference crushed material.
Consolidation (Odiometer):
On floors loaded by foundations, more or less seating occurs. Settling is a shortening or shortening of the volume, which can occur in short or long time, due to the reduced loads between the particles due to the applied loads in general. This consolidation settlements occur on clayey soils because sandy soils are considered as incompressible sediments in practice. It is called the consolidation of clay soils under constant stresses, depending on time, by throwing away the water in their bodies. The gradual increase in effective stress in the clay layer over a period of time will cause settling, which is referred to as consolidation. This process continues until the pore water pressure is completely dissipated due to an increase in total stress. The simplest consolidation situation is unidirectional consolidation that occurs under zero lateral deformation condition. The swelling process, which is the opposite of consolidation, is a slow increase in the volume of a floor under negative excessive pore water pressure. The properties that determine the behavior of a soil during one-way consolidation are determined by the consolidation test called "oedometer" test in the laboratory.
Three Axis Pressure Test (Uu-Cu-Cd)
Since the soil in the field is under the effect of three-axis stress, the closest shear strength parameters are obtained from field tests. Therefore, the most commonly used test method to determine the shear strength is the three-axis compressive strength test. This test is a test for determination of the strength of cylindrical specimens by three-axis loading and includes the data necessary to determine the elastic properties and strengths of the soils at different lateral pressures without considering the pore water pressure, internal friction angle, cohesion value, deformation modulus.
Direct Cutting Test
Shear strength of soils; in the calculation of the carrying capacity of foundations, in the design of roads and airports, in the balance analysis of slopes, in landfills and in the construction of bearing structures, etc. It is very important. The direct shear test is used to determine the cohesion, internal friction angle and undrained shear strength of soils. In the break box test; The soil sample is placed in a rigid box of rectangular or circular cross-section and consists of two parts, and with a shear force applied, the soil is forced to slide along the horizontal plane passing through the center of the sample. By applying normal stress on the sample, it is possible to consolidate the ground before cutting and to keep it under control of normal stresses during shear.
Spot Load Test
This test is carried out in order to classify the rocks according to their strength. It is also used as a strength parameter of rock material in indirect determination of other strength parameters such as uniaxial compressive strength and tensile strength and in some rock mass classification systems. However, there is now a tendency that the point load strength index is not used in the indirect determination of compressive and tensile strengths. As a result of the experiment; point load strength and strength anisotropy index are also calculated.
Plate Loading Test
The plate loading test is a field test to determine the bearing capacity of the ground. This test basically consists of loading a circular steel plate with a diameter of 30-75 cm at the basic level and determining the amount of seating corresponding to each load increase. The carrying capacity of the ground is calculated with the help of the sitting-load curve obtained as a result of the experiment.
Automatic Concrete Testing Machine 2000 kN
Concrete Test Hammer (Schmidt Hammer)
The Schmidt Hammer Test is the most common method used for non-destructive testing of concrete. The Schmidt Rebound hammer used in this method was developed in 1948 and is widely used all over the world due to its ease of use and application. This method measures the amount of bounce (R) as a result of the impact of the hammer made of hardened steel on the concrete surface. Although there is no theoretical correlation, empirical correlations can be obtained between the concrete strength and the amount of backlash. It has the same rankings with the surface hardness method
Soil Mechanics Laboratory is located on an area of more than 150 m2 and research and application studies are carried out in this laboratory. Soil Mechanics Laboratory is capable of conducting standard and advanced experiments of modern soil mechanics and soil dynamics at international standards.
Laboratory Experiments
- Determination of Unit Volume Weights
- Determination of Specific Weights
- Determination of water content
- Sieve Analysis
- Determination of Atterberg Limits (Liquid Limit-Plastic Limit- Shrinkage Limit)
- Sand Cone Test
- Standard Proctor
- CBR Test
- Consolidation (Odometer)
- Three Axis Pressure Test (Uu-Cu-Cd)
- Direct Cutting Test
- Spot Load Test
- Plate Loading Test
- Automatic Concrete Testing Machine 2000 kN
- Concrete Test Hammer (Schmidt Hammer)
