FIELD TESTS FOR CEMENT?

I can say that cement is the backbone ingredient of the concrete as it acts as a binder and has  ability to hold the structure together. Cement is supplied all over the world but the cement that we use for all sort of construction works should be tested in laboratory and at field also. Quality tests on cement at the construction site are carried out to ascertain the quality of cement supplied within a short period of time. It is necessary to check the quality of cement on site at the time of initial inspection. Laboratory testing is not possible in a short period of time, so at such times basic field testing for cement is done on the cement to check its quality. These tests give some idea about the quality of cement.

Test on cement in field (Construction site):

1.     Manufacturing date of cement.

2.     Colour of cement.

3.     Presence of lumps.

4.     Adulteration test.

5.     Temperature test.

6.     Float test.

7.     Strength test.

8.     Set test.

Manufacturing date of cement

With the passage of packing time of cement,the strength reduces.So,it is important to check the manufacturing date of cement. Generally, cement must be used before 90 days from the date of manufacturing.

   Time of cement vs reduction in strength

Colour of cement 

The colour of cement gives an indication of excess lime or clay and the degree of burning. After checking the date of packing,now open the cement bag and take a look at the cement inside the bag. The colour of the cement should be light greenish grey and it should be uniform in colour.

Presence of lumps

Cement develops lumps due to the presence of moisture from the atmosphere .Cement should be stored under specified condition so that water and moisture should never be an option for best quality cement But it is not good to use the cement that is effected with moisture for construction. Any bags that are delivered to the site with lumps must be discarded.

Open the bag and take a look at the cement, there should be no visible lumps. Push your hand into the cement bag, there should be no lumps inside. Any bag having lumps  must be rejected.

Adulteration test

This test is done by sensing the cement with the fingers.Take a pinch of cement and feel (rub) between the fingers. It should feel smooth when rubbed between the fingers. If it looks rough, it means that the cement is adulterated with sand.

Temperature test

When you insert your hand in bag of cement, it should give you cool feeling.It must be cold from the inside. If it is hot from the inside, it indicates that the process of hydration is taking place.

Float test

This test involves throwing a handful of cement into a bucket filled with water. Cement particles must float for some time before sinking

Strength test

This test involves the preparation of blocks of cement of dimensions 25 mm × 25 mm and length of 200 mm. It is immersed in water for 7 days. After this it has been put on 150 mm support and it has been loaded with a weight of about 340 N. If the block will show no failure, the cement is of good quality.

 Set test

A thick paste of cement with water is made on a piece of glass plate and kept in water for 24 hours. It should set and not crack.

Take 100 grams of cement and make a hard paste. Prepare a cake with sharp edges and pour on a glass plate. Dip this plate in water. Keep in mind that the shape should not be messed up during settling. It should be able to set and gain strength. Cement is also capable of setting under water which is called as  'hydraulic cement'.

 

For Testing:

Slump cone test, Silt content, Water absorption, Bulking of sand
Compaction factor test of concrete
Los Angeles Abrasion test on Aggregates