Civil Engineering and Geotechnical Testing

Lab Services Pte Ltd

We provide the following specialized testing services for soil, rock, concrete, bio swale, filter media for transition & drainage layers and also various grout mixes for soil stabilization and improvement works.

Services

Physical Tests

These tests assist in determination of the basic soil identity for classification purpose, eg. fine grained soil (SILT & CLAY) or coarse grained soil ( SAND & GRAVEL).  Classification tests to determine index properties are used extensively by engineers to discriminate between the different kinds of soil within a broad category.

· Moisture and Density determination
- Used in conjunction with many tests to determine the water content and in the calculation of forces  exerted by soil.

· Liquid and Plastic Limits (Atterberg Limit)
- To classify fine grained soil and the fine fraction of mixed soil.

· Particle Size Distribution ( Sieving and Hydrometer)
- Sieving methods give the grading of soil coarser than silt and clay.  The relative
  proportions of silt and clay can only be determined by means of sedimentation tests.

· Specific gravity/ Particle Density
- It is used for calculating of porosity & void ratio and particularly important when compaction and
  consolidation properties are being investigated.

 

SOIL

Mechanical Tests

Soil strength, deformation and permeability are characteristics of soil required for many construction projects in which total stresses, effective stresses, rate of settlement and drainage properties are important features.

· Compaction / CBR
- Standard compaction tests indicate the degree of compaction that can be achieved at different
  moisture contents with different compactive efforts.  Califonia bearing ratio (CBR) is an empirical test
  used for design of flexible pavements.

· Triaxial Compression Tests
- Unconsolidated Undrained (UU) triaxial test is usually  tested based on total stress
  analysis without pore water measurement to determine the undrained shear strength.
  The sample is sheared at a faster rate when no change in total moisture content is allowed.
- Consolidated Undrained (CU)/ Consolidated Drained (CD) tests are usually referred to as
   effective stress test which evaluate the Mohr Coulomb parameters c’ and Ф’.
- Stress Path Test may be applied to reproduce the history of stress and strain in the ground
  before and during construction.

· Direct shear box
- An alternative to triaxial tests although the latter are more versatile and more often used. An
  advantage is that samples of coarse grained soil can be more easily prepared than in triaxial test.
- Residual shear strength can also be obtained using shear box for slope stability problems where
  previous sliding has developed residual slip planes in-situ.

· One-dimensional Consolidation
- This test measures soil parameters m_v and c_v for simple calculations of the magnitude and rate of
   settlement of foundations.

· Permeability (Hydraulic Conductivity)
- Falling head test and Triaxial permeability test is suitable for soils of low to intermediate permeability
  usually range from 10^-4 m/s to 10^-10 m/s. The triaxial cell allows the direct measurement of permeability
  under constant head with a back pressure and confining pressures more closely consistent with the
  field state. The details of this test is specified in BS1377 : Part 6 : 1990.
- Constant head / Filtration permeability test is suitable only for Sand, bioretention Swale or cohesionless soil where  the hydraulic conductivity range from 10^-1 m/s to 10^-5 m/s . (360,000 mm/hr to 36 mm/hr)      

· Direct Simple Shear Test
- This advance soil test is for the measurement of constant volume strength and stress-strain characteristic of cohesive                  soils using a constant rate of simple shear deformation mode of loading. The constant volume condition is equivalent to the undrained condition for saturated specimens
- In this test method, the shear strength is measured is measured under plane strain conditions and the principle stresses continuously rotate due to the application of shear stress. This simple shear stress conditions occurs in many field situations including zones below a long embankment and around axially loaded piles.
- The values of the secant shear modulus obtained from this test can be used to estimate the initial settlements of embankments built on saturated cohesive soils due to undrained shear deformation.

·  Cyclic Simple Shear
-  Cyclic strength test is conducted under undrained conditions to simulate essentially undrained field conditions during earthquake or other cyclic loading.
-  Particular application in liquefaction studies in clay where cyclic stresses can be applied.
- This test can provide constant cyclic load or constant cyclic deformation to determine the secant modulus and damping  coefficient for cyclic axial loading of a prismatic soil specimen in hydrostatically consolidated, undrained conditions. These parameters are important parameters used in dynamic, performance evaluation of both natural and engineered structures under dynamic or cyclic loads such as caused by earthquakes, ocean wave or blasts. It can be used in dynamic response analyses including, finite elements, finite differences, and linear or non-linear analytical methods.              

             Example of cyclic result— cyclic.pdf       

Chemical Tests

This part of test covers the determination of the amount of chemical substances, including organic matter, in samples of soil and ground water.  Some electrochemical and corrosivity properties of soil and water samples are also included in the following test list.

· pH value
- Measures the acidity or alkalinity of  soil and ground water.

· Chlorides/ Salinity
- Results used in conjuction with those for sulphate, pH to assess aggressiveness
  of subsoil condition to concrete.

· Sulphates
- Assesses the aggressiveness of soil or groundwater to buried concrete.

· Organic Content
- Detects the presence of organic matter able to interfere with the hydration of Portland cement in
  cement pastes.

· Carbonate Content
- Confirms the presence of carbonates, which often indicates cementing.

· Electrical Soil Resistivity
- This is usually used in soil corrosivity study for underground pipelines, a decrease in resistivity relates
  to an increase corrosion activity and therefore dictates protection treatment to be used.  Soil electrical
  resistivity is also useful in earthmat / earthing system design for power plants, transmission lines and
  substation, etc.

· Thermal Soil Resistivity/ Thermal Conductivity
- The measurement of soil thermal resistivity / conductivity of a soil will enable the user to properly
  install and load underground cables.

Tests for soil include physical, chemical and mechanical properties.  For more details and information on soil testing, please contact us for a non-obligatory discussion.

Our address:

10 Ubi Crescent

#04-79 Lobby D

Ubi Techpark

Singapore 408564

Phone: (65) 6749 6009

Fax    : (65) 6749 3936

Email  : enquiry@labsvcs.com.sg