Civil Engineering Tests

Cement we use may go bad during transportation and storage prior to its use in work.We need to test the cement for a good quality and better performance in concrete mixtures. Broadly there are two tests for cement-

• Field Testing
• Laboratory Testing

Field Testing
It is generally done when cement is used for small or minor works. Following are the field tests-

• After opening the bag of cement, we should give a good look, There should not be any visible lumps present in it. Colour of cement should be greenish grey.
• It should give a smooth and gritty feeling when pinch of cement is feel between the fingers.
• If we thrust our hand into the cement bag, it must give a cool feeling.There should not be any lumps inside.
• If we throw some amount of cement into a bucket of water, it should float sometime before sinking.
• A cube made from a stiff paste of 100gm cement and little water is to be put in a glass plate. The glass plate is taken slowly under water in a bucket. The shape of the cube should not be deformed while taking into water. After 24 hours cube should retain its original shape.

If a sample of cement truly satisfies the above tests we may say that the cement is not bad. But the above tests do not really indicate that the cement is really good for important work or big structure. For using cement in important and major structure, it should satisfy the Indian Standard specifications. It is possible only in laboratory testing to confirm the requirements of specified physical and chemical properties.
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This is an in situ test for settlement computation in granular soils. It is difficult to procure the undisturbed samples of granular soils which are non-cohesive. Hence, the laboratory tests cannot be used to obtain the compressibility characteristics of granular soils. Plate Load Test is one of the most frequently used field tests where the test plate simulates a foundation. The method may also be used to evaluate the ultimate bearing capacity, the shear strength and deformation parameters of the soil at the ground surface, in trenches, or in pits.

The plate load test may be carried out in all soils, fills and rocks. The suitable soil for the test is coarse grained and composite soils as well as stiff to firm fine-grained soil. The test should normally not be used for very fine-grained soil. In the progress of the test, care should be taken to ensure that the loading plate is not placed directly on the particles than one-quarter of its diameter.

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The unconfined compression test is a type of triaxial test in which the confining pressure is taken as zero. The test is onlybe conducted in clayey soil specimens which can stand without confinement because of this case. The test is generally performed on intact (non-fissured), saturated clay specimens. Although the test can be conducted in a triaxial test apparatus it is more convenient to perform it in an unconfined compression testing machine. There are two types of machines as described below:

1. Machine with a spring
In this type of testing machine a loaded spring is used. It consists of two metal cones which are fixed on horizontal loading plates supported on the vertical posts. The upper loading plate is fixed in position, whereas the lower plate can slide on the vertical posts. The soil specimen is placed between the two metal cones

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The consolidation test for soil samples is conducted in laboratory scale to determine the compressibility behavior of the soil specimen. The test is performed in the consolidation test apparatus, known as the consolidometer or an oedometer. Consolidometer consists of a loading device and a cylindrical container which is called as a consolidation cell. The soil specimen is placed in the consolidation cell between the top and bottom porous stones. The consolidation cells are of two types as follows:

1. Floating or free ring cell in which both the top and bottom porous stones are free to move. The top porous stone can move downward and the bottom stone can move upward as the sample consolidates.

Source: Soil Management India

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AIM OF THE EXPERIMENT:
To determine the Flakiness Index of the given sample of course aggregate.

CODE OF REFERENCE:
• IS 2386(Part 1):1963 Methods of Test for Aggregates of Concrete- Particle Size and Shape. Reaffirmed Dec 2016
• ASTM 4791-10: Standard Test Method for Flat Particles, Elongated Particles or Flat Elongated Particles in Coarse Aggregates, American Society for Testing and Materials.
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The following laboratory tests are commonly used for determination of the strength of rocks:
1. Unconfined compression test
2. Triaxial compression test
3. Splitting tension test
4. Beam bending test
5. Ring shear test

All these tests are briefly described as below:
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AIM OF THE EXPERIMENT:
To determine the undrained shear strength of a sandy to silty soil.

CODE OF REFERENCE:
• IS 2720 (Part 13)- 1986 Methods of test for soils: (Part -13) Direct Shear Stress
• IS 2720 (Part 2)- 1973 Methods of test for soils: (Part -2) Determination of water content

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AIM OF THE EXPERIMENT
To determine the unconfined compressive strength of cohesive soil in the laboratory.

CODE OF REFERENCE
• IS 2720 (Part-10)-1973 Methods of test for soils: Part 10 – Determination of unconfined compressive strength.
• IS 2720 (Part-2)-1973 Methods of test for soils: (Part 1) – Determination of water content.
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AIM OF THE EXPERIMENT: To determine the gradation of coarse aggregate by sieve analysis.

CODE OF REFERENCE:

• IS 383 (1970): Specification of coarse aggregate and fine aggregate from natural sources for concrete [CED 2: Cement and Concrete]

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AIM OF THE EXPERIMENT:
To determine the stripping test of aggregates on bituminous mix and to ascertain the suitability of road aggregates for bituminous road construction

CODE OF REFERENCE:
• IS: 6241- 1971 Methods of Testing Tar and Bituminous Materials: Determination of Stripping value of aggregates, Bureau of Indian Standards.

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