The laboratory “Ground Mechanics” at “Baugrund Institut Knierim” Ltd. has been created in 1993. We provide maintenance of high quality of the trials, which is guaranteed since 2004 until today, and is accredited by Executive Agency “Bulgarian Accreditation Servise” in accordance with the requirements of BS EN ISO 17025 for a wide range of tests and test sampling.
The independence of the laboratory “Ground Mechanics” guarantees the satisfaction of the requirements and needs of customers by offering attractive prices of tests and individual discounts.
CLASSIFICATION AND PHYSICAL PARAMETERS
Water content – percentage of water by weight method. Performed by BS, BDS, CEN ISO / TS, ASTM, DIN.
Volume density and density of the skeleton – Defined as wet and dry soil density. Performed by BDS, CEN ISO / TS, ASTM, DIN.
Specific density – Density of the particles with or without taking into account of the closed pores in 100 ml or 250 ml filled pycnometer with water or an organic solvent. Performed by BDS, CEN ISO / TS, ASTM, DIN.
Grain content – Represents weight distribution of the fractions in the soil. Determined by sieve (sieving), sedimentation or combined analysis by BDS, CD CEN ISO / TS, ASTM, DIN.
Aterberg limits – liquid limit, plastic limit, plasticity index, shrinkage limit, Schrumpfgrenze. They are determined with a penetration cone or a bowl of Casagrande by BDS, CD CEN ISO / TS, ASTM, DIN.
Content of organic substances – it is determined as a loss by ignition up to 440°C, 550°C or 900°C by ASTM, DIN.
Carbonate content – it is determined by gas-metric method of decomposition with hydrochloric acid. Performed by BDS, ASTM*, DIN*.
Contents of water soluble salts – it is determined by BDS as a total content of soluble salts by water extraction.
Water absorption – Ability to absorb water by Enslin / Neff by DIN.
In laboratory tests are performed to determine the strength parameters “friction angle” and “cohesion” with full and effective stresses as follows:
Direct) shear test – in shear devices type Teylor from the company “Wykeham Farrance”, with a sample diameter of 80 mm, 2 shear devices. Tests are performed by BS, SD CEN ISO / TS, ASTM, DIN, BDS *.
Shear device Teylor type for determining the parameters of contact friction between geo synthetics, and geo synthetics and mineral materials, with a large cassette sizes 35 cm x 35 cm;
Triaxial shear devices for testing of samples from 35/70 mm to 80/160 mm, 4 pieces, with the opportunity of applying the following test shemes:
- UNCONSOLIDATED-UNDRAINED TEST (UU)
- CONSOLIDATED-UNDRAINED TEST (CIU)
- CONSOLIDATED-DRAINED TEST (CID)
Tests are performed by BDS, CEN ISO / TS, ASTM, DIN, BS *.
Determination of undrained strength with falling cone in CEN ISO / TS.
Determination of strength of uniaxial pressure and undrained strength in CEN ISO / TS, ASTM, DIN.
Determination of water permeability (Durchlaessigkeitsbeiwert) of cohesive /non-cohesive soils:
- In a Oedometer with a falling head – used to roughly determine the permeability, as a quick method. Tests are performed by BDS, CEN ISO / TS, DIN – the laboratory has two devices with a diameter of 100 mm of the test sample;
- In triaxial conditions under constant gradient with or without preliminary water saturation of the test sample – used as a most precision test method for determination of the permeability index/ Durchlaessigkeitsbeiwert/, suitable for clays. Tests are performed on CEN ISO / TS, ASTM, DIN, and for this purpose the laboratory has 15 triaxial cells with a diameter from 50 mm to 100 mm of the test sample.
Determination of water permeability (Durchlaessigkeitsbeiwert) of non-cohesive soils (sand, gravel, ballast, drainage concrete) – by BDS, CEN ISO / TS, ASTM, DIN. The test devices used have a constant pressure head with a diameter of the trial body 80 mm, 150 mm and 300 mm, suitable for unbound materials with a maximum grain size 63 mm.
Consolidation in a Oedometer – used to determine the deformation parameters (compression module, settlement, coefficient of consolidation, and pre-consolidation pressure) of undisturbed or laboratory compacted test samples with diameter 70 mm and 100 mm with loads up to 3.2 MPa. The laboratory has 25 dead load oedometers.
Isotropic and anisotropic consolidation of samples diameter up to 80 mm, in triaxial conditions, determination of deformation modules based on triaxial tests.
Determination of free swelling, swell pressure, collapsibility of soils. Tests are made in compression devices with dead load.
Static Plate load tests – The laboratory is equipped with plates with sizes 300 mm and 600 mm.
California Bearing Ratio (CBR) * – executed in situ or as laboratory test. The test is performed according to ASTM or BDS, EN 13286-47: 2012 *: Unbound and hydraulically bound mixtures. Part 47: Test method for the determination of California bearing ratio, immediate bearing index and linear swelling.
COMPACTION AND CONTROL OF COMPACTION OF CONSTRUCTION SOILS
Determination of the maximum density and optimal water content is performed by BDS, ASTM, DIN, EN ISO, applying a normal or modified compaction effort in molds 100 mm and 150 mm. The laboratory has equipment for automatic and manual compaction.
Specifically, tests are conducted under the following standards:
BDS 3214: 1985 – Construction soils. Methods for laboratory determination of standard densities of bound and unbound soils;
BDS 17146: 1990 – Construction soils. Determination of the maximum density of the skeleton and the optimal water content of soil. Proctor method;
DIN 18127: 2012 Baugrund, Untersuchung von Bodenproben. Proctorversuch (Construction soils, testing of earth samples. Proctor testing)
ASTM D698 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort
ASTM 1557 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort
BS EN 13286-2 Unbound and hydraulically bound mixtures. Test methods for the determination of the laboratory reference density and water content. Proctor compaction
The testing laboratory “Soil Mechanics” is performing sampling in the scope of its accreditation, as well as field tests to determine the Density and Unit Weight of Soil in Place by Sand-Cone Method and by thin-walled soil sampler.
The laboratory specializes in performing field and laboratory control in the execution of clay liners in landfill construction, having the opportunity to test all the characteristics, required for the material controll and compacted layers in acc. With Annex 2 of Regulation № 6 / 08.27.2013 for the conditions and requirements for the construction and operation of a landfills and other facilities and installations for pretreatment and disposal of waste.
* – testing outside the scope of accreditation