5 compressive strength of cement

Concrete Technology, Construction material, Cement

1. University of Salahaddin/ College of Engineering 2015-2016
Dept. Of Dams & Water resources Engineering By: Goran Adil
Construction Material 1

Test No. 05
Test Name: Compressive strength of cement.

Introduction:
The compressive strength is one of the important properties of cement. Strength tests are not made
on neat cement paste because of difficulties in obtaining good specimens and in testing with a
consequent large variability of test results. Cement-sand mortar and, in some cases, concrete of
prescribed proportions, are used for purpose of determining the strength of cement.

Purpose:
To find the compressive strength of the cement.

Materials:
1- Ordinary Portland cement.
2- Standard sand ( Rounded single size particles passed on sieve 850 µm (No.20) and not
more than 10% pass through sieve 600 µm (No.30) ).
3- Water.

Apparatus:
1- Compression testing machine with a capacity at least 500 kN and accuracy 1 kN.
2- Steel cube moulds of 70.7 mm internal dimensions.
3- Cube vibrating machine.
4- Balance,
5- Water bath for curing.
6- Container, Hand gloves, Trowel, and Scoop, Glass Graduates.

Procedure:
1- Prepare cement-sand mortar, with a mix proportion 1:3 and water to both weights of
cement and sand ratio of 10 %. Use 200 grams of cement.
2- Mixing cement and sand at dry condition for one minute then add the water and continue
the mixing for 4 minutes.
3- Oiling the internal faces of the mould.
4- Place the mould on the vibrating machine and fill it with a mortar.
5- Operating the vibrating machine for at least 2 minutes or until full compaction has
achieved.
6- Level the surface of the mortar and mark on it.
7- Store the moulds in air under temperature about 20±1
o
C and a minimum relative humidity
of 90 %, for 24±0.5 hour.
8- Open the moulds and take out the cubic specimens, then submerge in a water bath of
temperature about 20±1
o
C up to the date of the test.
9- Testing the specimens at the age of 3, 7 and 28 days by compression testing machine and
apply the load with a gradual rate up to the failure.
10- Record the load required for the failure. Compute the compressive strength by dividing
the failure load by the sectional area of the cube.
11- Find the average compressive strength of three cubes.

2. University of Salahaddin/ College of Engineering 2015-2016
Dept. Of Dams & Water resources Engineering By: Goran Adil
Construction Material 2

Calculation:

Compressive strength of cement A
p
 MPa.
Where: P = failure load (N).
A = sectional area of the cube (mm
2
)

Specification:

Iraqi standard specification 5/1984
Age 3 day 7 day
Compressive strength of ordinary Portland cement (MPa) 15 23


Discussion:
- Compare the test results with the standard specifications.
- What is the significance of this test?

3. University of Salahaddin/ College of Engineering 2015-2016
Dept. Of Dams & Water resources Engineering By: Goran Adil
Construction Material 3

Data Sheet
Compressive strength of cement



Test No.: 5
Test name: Compressive strength of cement


Name of the student:
Group No.:
Date:




Group
No.
Age
day
Failure load
N
Compressive strength
MPa




Average Compressive strength =






Results: