GEOS combines the diverse specialisms of mineralogy, chemistry, geology, and materials science into a unique soil mechanics lab. Testing can be applied in, among other things: geotechnical design, environmental soil research, hydraulic engineering, and land reclamation.
For civil engineering analyses of land, you are at the right address at GEOS. Be it for soil mechanical classification via tests on stirred soil or drilling descriptions, chemical analysis to determine concrete degradation or soil mechanical analysis to determine the sliding resistance and settlement of soils. Completed with probe charts our laboratory research forms the basis of well-founded geotechnical advice.
Soil improvement with lime, cement or bentonite leads to increased bearing capacity. However, also the shear resistance and water permeability are affected. We measure for you what that influence is.
- Classification / identification
- Chemical and mineralogical analysis
- Soil mechanical testing
Classification and identification
To support soundings and drill descriptions soil samples are tested for many essential parameters: grain size distribution, plasticity and the content of organic and lime-like substances. In the case of undisturbed samples, the volume weight and shear strength are also determined. Combination of these data leads to the unambiguous designation of the soil type. For naming, the system of Sb260, NF P11-300 / GTR, NEN 5104 or ISO 14688 is used. The classification indicates the possibilities of reusing the land before the start of a construction project and is therefore of high economic value. Because of the low costs, a classification study is a smart investment.
After determining the particle size, plasticity index (Atterbergs limits), the content of lime and organic matter, the soil type of your supplied sample can be determined. Some systems use a slightly different combination of tests; no problem: GEOS has experience with various guidelines and test methods.
Classification based on tests gives an unambiguous, objective assessment of the soil characteristics and is a valuable addition to a visual drill description.
Chemical and mineralogical analysis
Mineralogical and chemical research is used to gain insight into the specific behavior of soil. GEOS regularly determine the mineralogical composition (including glauconite content) and the granular form to explain phenomena in geotechnical works.
Another type of research is a screening of chemical properties of soil and groundwater samples to determine the environmental class of a building site. From different parameters, an environment class described by EN 206-1 is recommended for the concrete to be used.
Adequate advice at the initial stage of a project prevents extra costs caused by over dimensioning or the failure of the material.
With extensive experience in geology, GEOS is the ideal partner to determine the mineral composition of a soil sample. In the case of suspicions of (insufficient) dosing of bentonite or cement or the presence of glauconite, a composition study removes the doubts. Various techniques are used for this purpose: X-ray diffraction (XRD), chemical research (XRF and ICP), petrography (grinding plates) and determination of specific surface area.
Soil mechanical testing
Soil mechanical tests are performed on undisturbed samples, or samples constructed in the laboratory.
With these tests, we look at the deformation and failure behavior of soil at different loads. From laboratory tests, we determine, among other things, the settlement and the shear stresses of soil.
GEOS has a substantial capacity in the field of oedometer (compression) and triaxial testing. In the past years, we have contributed to numerous large-scale works in polder and port areas.
Soil improvement with lime, cement or bentonite leads to increased bearing capacity. We measure this via proctor curves and carrying capacity measurements (CBR and IPI). However, also the shear resistance and water permeability are influenced by the addition of soil improver. We measure for you what that influence is.
APPLICATION OF RELEASED SOIL
Released material during excavations can usually be used as a building material. With sand it is about drainage sand, fill up or fill sand. However, it can also be used as raw material for concrete and asphalt. Inspections of samples are made on the basis of Sb250, RAW and European standards.
Clay is inspected as a raw material for the ceramic industry or hydraulic engineering. The erosion resistance is investigated here.
with hydraulic binders and bentonite
To improve the carrying capacity or water tightness of the natural soil, it is treated with hydraulic binders (such as cement, lime) or bentonite. Depending on the type of soil and the water content, the type of binder and the dosage is determined. The optimal conditions are investigated in the laboratory via a series of classification tests, Proctor curves and carrying capacity (CBR, IPI or compressive strength), E-modulus and permeability tests. Control measurements at execution consist of density measurements, plate tests, drill cores and stitch samples for permeability and pressure strength determination.
SOIL MECHANICAL STRENGTH PARAMETERS AND SETTING
During excavations and the construction of earth masses such as embankments and dikes, the soil enters a different stress state. To prevent shearing and to predict settlements, the stability of the new condition must be known. The main soil-mechanical parameters are determined on the basis of laboratory tests on undisturbed samples. The settlement behavior is determined by compression tests (oedometer) or the constant rate of strain (CRS) test. Shear characteristics (phi and c), deformation behavior and slope stability are determined via triaxial tests or direct shear tests.
research water permeability
The water permeability of the soil is a critical parameter in environmental soil research. After all, the spread of contamination is largely determined by water transport. Also in the case of pumping or construction of drainage for rain drainage, the permeability of soil layers is controlled. The permeability k is measured in the lab, preferably on undisturbed samples via the constant head or the falling head method.
In wet, low areas dikes protect against flooding. The dikes have been constructed with clay or peat and must therefore also be investigated as soil parcels. The clay used is tested in advance for the suitability, in particular, the erosion resistance. With existing dikes, the residual deformation parameters are determined on the basis of triaxial, compression and CRS tests.
Before a pavement is applied, a foundation layer is first laid on the natural soil. This layer often consists of a stone mixture, for example, building rubble. In peat areas, light materials should be used to minimize settlement. Special requirements are often imposed on the foundation layer with respect to hardness and elasticity. GEOS examines the suitability of the stone mixture in various areas: compactness, density, strength, and hardness. Cores bored from work are examined for compressive strength and elasticity.