Field Tests on Construction Materials

     

Cement sample for tests

    In general, Construction materials are should check their qualities and properties before use at the site. Because of the poor quality materials reduced the life of the building and it causes major hazards to the persons who are living or using the buildings.

So, It may the Organizations or the single persons all should check the construction materials in proper and maintain records for their buildings and safety. it is everyone's responsibility to be aware of the material's quality used in our buildings.

Tests on Building stones:-

    For the Building stones, some tests are simple to conduct in fields, and some tests can be done in Laboratory. Accordingly, they may be grouped as field tests and laboratory tests (IS:1121, 1974 and IS:1124, 1998).

Field Tests:

The simple tests or Field tests are,

1. The Absorption Test, 
2. Smith's test, 
3. The Toughness Test, 
4. The Hardness Test, 
5. The Acid Test and 
6. The Crystallization Test.

Laboratory tests:

The Laboratory tests on stones consist of,

1. The Attrition Test, 
2. The Crushing Test, 
3. The Freezing and Thawing Test, 
4. The Hardness Test, 
5. The Impact Test, 
6. The Microscopic Test.

Field Tests:

1. The Absorption Test,

    Usually, this test is called the water absorption test. This is a simple test conducted on all stones. It consists of keeping a cubical specimen of the stone of about 50gm weight immersed in water for 24 hours and finding the volume of absorbed water. This is represented as a percentage of absorption by weight. This percentage should not be more than 0.6%. This test is also called the electrical resistance test.

         2. Smith's test, 

    This test is conducted to find the presence of earthly matter or the deterioration of stones when immersed in water. A specimen of the stone is placed in a glass container with water and stirred vigorously. It is placed in water for at least 24 hours. If the water shows turbidity, then the stone is assumed to contain earthly substances. This test is to be conducted for all stones.

        3. The Toughness Test, 

               It is a rough test without any rigid specification or procedure. A stone is struck by a hammer to gauge its toughness of the stone. The force required to break the stone reflects the toughness of the stone.

        4.The Field Hardness Test, 

                This test is also called Moh's scale of hardness test. This is a simple test in which the hardness of the test is based on the hardness of the surface. The surface of the stone is scratched with the help of a penknife, and the hardness is gauged based on the relative abrasiveness of minerals (the soft being talc and the hardest being diamond). Such a classification is given by Mohs and the scale is divided into the ten following scales,

1. Talc
2. Gypsum
3. Calcite
4. Fluorspar
5. Apatite
6. Orthoclase feldspar
7. Quartz
8. Topaz
9. Corundum (sapphire)
10. Diamond

            Thus, if a marking has been done with a pen knife on the surface of the stone, will be equated to the hardness of the Calcite. Hence the hardness, H=3. A siliceous rock surface cannot be scratched which may be equated to that of quartz and in this instance, H=7.          

        5.The Acid Test 

            This test is performed to determine the presence of alkaline or lime content. This test consists of placing a cube of 50 to 100 gm weight in 1% hydrochloric acid for one week. If the corners of the cube show roundish and loose particles deposited on the surface, the stone has some alkaline content. If the stones exhibit fluorescence when subjected to the action of acids, then it reflects the presence of lime content. Stones that do not react to sulphuric acid are highly fire-resistant.

        6.The Crystallization Test.

            Due to crystallization on reaction with some chemicals, the stones may show a loss of weight and some defects. This test consists of immersing a cubical specimen of 40mm side in sodium sulfate solution for 2 hours and then drying it in an oven at 100℃. This procedure is repeated five times. The loss of weight and the presence of cracking on the surface are noted. The presence of visible defects and loss in weight should be minimal indicating high durability and good resistance to weathering.