National Lab for Soil Investigation & Building Materials Testing

Soil investigation is to carry out physical testing on site to understand the ground conditions for geotechnical design for foundations, retaining walls and soil improvement.  It allows the engineer to work out safe and economical design of a project and inform the construction engineer about the material and conditions he will encounter in the field.

Its objective is to determine engineering properties of soil, to select a suitable type of foundation, to estimate the probable and maximum differential settlements and mainly to find the bearing capacity of the soil, which could be used in the engineering design and specifications of the proposed construction projects like building, infrastructures, villas, etc.

The site works involves auger boring including sampling and Standard Penetration Test (SPT), trial pits, ground water level measurement, and followed by laboratory analysis for particle size distribution and chemical analysis. 

The concrete is required to support heavy load in all structure, therefore, it is a must to be tested.

The compression test is used to determine the material behaviour under a load.  The maximum stress a material can sustain over a period under a load (constant or progressive) is determined. Compression testing is often done to a break or to a limit.  The concrete samples could be in the form of cubes or cylinder, and different types of blocks, interlocks, tiles, kerbstone and so forth.

In concrete investigation, some non-destructive testing could be provided like Schmidt Hammer, Ultrasonic Pulse Velosity and Half Cell Potential Mapping, while other testing are categorized as destructive like drilled core test and compression while some durability test could be applied also like Water Absorption, Water Permeability and the like.

The Tensile Test is the commonly conducted test for Steel Bar.  Rebar, also known as reinforcement steel and reinforcing steel, is a steel bar used in reinforced concrete, as one of the main parts in reinforced cement concrete structure.

The testing of Bend and Rebend are done to evaluate the ductility of the reinforced bar.  The bend is performed by bending the steel bar at the midpoint resulting in bending without fracture, while the Rebend test is performed to measure the effect of strain ageing on steel.  And Tensile test is a destructive process that provide information about tensile strength, yield strength and elongation which the steel bar involves applying increasing load up to the point of failure in both upper and lower crossheads.

Aggregates are inert granular materials like sand, gravel and crushed stones.  The material used for mixing with cement to form a concrete which gives volume, stability, resistance to erosion and other desired physical properties to the finished product, and are tested for strength, hardness, shape, and water absorption.

The various testing of aggregates includes the impact value which gives a relative measure of the resistance to sudden impact, while crushing value gives a relative measure of the resistance to crushing under applied load.  The specific gravity and water absorption is to determine the density of the essentially solid portion of the aggregate.  The LOS Angeles machine is used for testing aggregates for resistance and degradation.  The Flakiness index of an aggregate sample is found by separating the flaky particles.  The Sieve Analysis helps in determining the size of a granular material like aggregates and also all are required to meet a minimum strength valve, as defined by the 10% value test.

The common chemical analysis for Soil, Water, Aggregates and Concrete, for construction materials, are their chloride content and sulphate content which their anions are considered as secondary contaminants.  The determination of chloride and sulphate is important since these anions can have a corrosive impact on concrete structures.

There are two methods in determining the chloride and sulphate content, one is by water-soluble chloride content and water-soluble sulphate content, and the other is by acid-soluble chloride content and acid-soluble sulphate content.