Construction Cost Estimating

      

Some useful tips to check the quality of cement on site

In this civil engineering article, you will be familiar with some preliminary tests for checking the quality of cement at the jobsite.

1. The color of the cement should have been invariable and available in different types like grey for ordinary port land cement(OPC) and blackish for portland pozzolana cement(PPC).

2. By rubbing with fingers, the cement should feel similar to flour. If it feels rough, there is adulteration, with sand/earth.

3. By putting the hands in a bag or heap of cement, it should feel cool. By providing a small quantity of cement in a bucket of water, it should submerge and should not sail on the surface.

4. Cement does not contain any firm lumps. These lumps are produced by engrossing the moisture from the atmosphere. Any cement bag with such lumps should not be used.

Physical Characteristics of Cement:

Min. Compressive Strength 33 Grade 43 Grade 53 Grade
3 Days 16 N/Sq.mm 23 N/Sq.mm 27 N/Sq.mm
7 Days 22 N/Sq.mm 33 N/Sq.mm 37 N/Sq.mm
28 Days 33 N/Sq.mm 43 N/Sq.mm 53 N/Sq.mm

N stands for newton

Least initial Setting Time of Cement = 30 Minutes Highest Final Setting Time of Cement = 600 Minutes or 10 hours.

Quality and Quantity of Cement:

1. Weight of one bag of cement is 50 Kgs
2. 1 ton of cement equals 20 bags
3. No of cement bags = Tonnage of cement x 20
4. Tonnage of cement = No. of Bags/20
5. Storage capacity of cement godown = 20 bags per Sq. M of plan area.
6. Capability of a truck for transporting cement =250 to 300 bags(12.5 tons to 15 tons)

Diminution in Strength of Cement due to Storage:

1. 20 % reduction in strength when stockpiled for 3 months
2. 30 % reduction in strength when stockpiled for 6 months
3. 40 % reduction in strength when stockpiled for 12 months
4. 50 % reduction in strength when stockpiled for 24 months

Storage Specifications of Cement:

1. Distance from wall =30 cms or 1ft.
2. Distance from floor = 15 – 23 cms to be kept on wooden sleepers
3. Bags to be stacked in layers or 10 -12
. No. of cement bags in a row = 15
5. Ventilation and Lighting : There should be no openings to block the movement of air to minimize moisture. The natural lighting can only be provided with glazing.

Some useful tips to check the quality of cement on site