Field test on cement, cement storing, Effects of storing cement on its properties

Field test on cement

Before the laboratory testing or use of cement field test on cement on cement are required for immediate detection of unsuitability of cement.

1)    Open the bag and observer the cement. There should not be any visible lumps. If any lumps found it should be powered by pressing between thumb and fore finger if it does not turn into powder the cement is considered have been spoiled by the air setting.

2)    Thrust your hand into the cement bag, it should feel cool.

3)    Rub the cement between finger tips by taking the pinch of the cement. It should not feel gritty but should be smooth in feel.

4)    Throw a handful of cement on water surface in a bucket. The cement should float in case of cement is of good quality and it sinks it contains some impurities.

5)    The colour of cement should be uniformly greenish grey.

6)    It should not feel oily when touched.

7)    Take 100 grams cement and make a steep paste by adding very little water. Pat a cake out of this paste on a glass plate. Submerge the glass plate with the cake at a bottom of a water bucket. After 24hr the cake should not loss its shape and strength.

 

Storing of cement on site

Cement has great affinity towards water and it observe moisture from humid air. It forms lumps, becoming harder and becomes useless.

Hence following precaution should be taken while storing cement.

·        cement should be store in a special watertight shed with a dry and damp proof for door, water tight walls and leak-proof roof.

·        The stacks of cement bag should be placed at a distance of at least 30 cm from walls.

·        Width of stacks should not be exceed 3 meter.

·        stack should contain maximum 15 bags.

·        Bin bag receive first and use first which is come at site on first.

·        bags should be stacked on raised platform.

·        Stacks platform have sufficient aisles for movement between rows and stacks.

 

Effects of storage of cement on its properties

v Sealed bag of cement is opened, oxygen in air start reacting with the ingredients as well as the humidity in the starts reaction with the ingredients.

v Due to long storage, cement loss its strength, becomes lumpy.

v Cement loss its capacity for hydration becomes unusable.

Effects of storage of cement

Fresh cement from factory à 100% strength.

Cement	Reduction in strength
After 3 months	15%
After 6 months	25%
After 1 year	40%
After 2 year	52%

Hence it is advisable to use cement within 3 months at maximum