Question

The following information related to ordinary portland cement is available.

a) Initial setting time - 30 min,

b) Final setting time - 10 hours

c) Cement water combination action - 10%

So which of the following statements is true?

1. b and c
2. a and b
3. a and c
4. a, b and c

Answer 1

Correct Answer - Option 2 : a and b

Properties of Portland cement:

Properties	Value
Initial setting time	Should not be less than 30 min
Final setting time	Should not be greater than 10 hrs
Fineness	% Residue by weight should not be greater than 10%
Soundness	Should not be greater than 10 mm
Specific gravity	3.15
Compressive strength after 3 days Compressive strength after 7 days	15 N/mm2 22 N/mm2

Ordinary Portland cement:

As per IS269, this is the cement used for normal concrete construction.

It has adhesive and cohesive properties so as to render it to form a good bond with other materials.

Portland cement is the most important type of cement and wisely used. It consists of the following component:

Approximate oxide composition limits of ordinary portland cement are as follows:

Oxide	Percentage Content
CaO	60 - 67
Si02	17 - 25
Al2O3	03 - 08
Fe2O3	0.5 - 6.0
MgO	0.1 - 4.0
Alkalies (K2O, Na2O)	0.4 - 1.3
SO3	1.3 - 3.0