Sab 2112 - L3 Testing Of Cement
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TESTING OF CEMENT
Why do we have to conduct the tests? To ensure the quality of cement To determine the properties of cement – Chemical properties – Physical properties
Test should be conducted according to the relevant standard MS 522 Pt. 1, 2, 3 – OPC BS 12
Tests of Cement Chemical composition Fineness Setting time Soundness Strength
CHEMICAL COMPOSITION To determine the amount of C3S, C2S, C3A, C4AF Conducted at the cement factory For research – need to be conducted
FINENESS Rate of hydration depends on the fineness of cement Specific surface (m2/kg) Can be determined by the air permeability Lea and Nurse or Blaine methods
SETTING TIME Describing the stiffening of cement paste OR the change from fluid to a rigid state Cement paste = cement + water Setting is mainly caused hydration of C3A and C3S together with C2S Accompanied by increase in temperature (heat)
Type of Setting Initial set – corresponds to rapid rise of temperature Final set – corresponds to the peak temperature/strength False set – sometimes occurs within a few minutes of mixing with water, no heat is evolved, concrete can be remixed
Cont. Flash set – caused by the rapid reaction between C3A and water Prevented by the addition of gypsum
Setting Time For OPC and RHPC: – Initial setting time – not less than 45 minutes – Final setting time – Not more than 600 minutes
Setting time is affected by: temperature and relative humidity
SOUNDNESS It is important that the cement paste, after setting, does not undergo a large change in volume i.e. expansion Expansion may occur due to reactions of free lime, magnesia, and calcium sulphate Cement exhibits expansion is classified as unsound Can be determined by Le Chattelier test
STRENGTH Strength test is not made on neat cement Two methods: – Mortar test – Concrete test
Mortar Test Mortar = cement + sand = water Mass of water = 10% of the mass of the dry materials Sand – standard sand, one size, spherical shape Cube size of 71 mm Materials are mixed and compacted using vibrating table
Cont. After 24 hours demould the mortar cubes and cure in water until the day of test Average of three samples According to MS 522: Pt. 1 – OPC – 23 MPa at 3 days
41 MPa at 28 days – RHPC – 29 MPa at 3 days
46 MPa at 28 days
Curing Tank
CONCRETE CUBE Concrete = cement + aggregates + water W/C ratio : 0.6, 0.55, 0.45 Cube size of 100 mm Preparation procedures are the same as mortar test – OPC – 11.5 MPa at 3 days
26 MPa at 28 days – RHPC – 18 MPa at 3 days
33 MPa at 28 days
Thank You
Why do we have to conduct the tests? To ensure the quality of cement To determine the properties of cement – Chemical properties – Physical properties
Test should be conducted according to the relevant standard MS 522 Pt. 1, 2, 3 – OPC BS 12
Tests of Cement Chemical composition Fineness Setting time Soundness Strength
CHEMICAL COMPOSITION To determine the amount of C3S, C2S, C3A, C4AF Conducted at the cement factory For research – need to be conducted
FINENESS Rate of hydration depends on the fineness of cement Specific surface (m2/kg) Can be determined by the air permeability Lea and Nurse or Blaine methods
SETTING TIME Describing the stiffening of cement paste OR the change from fluid to a rigid state Cement paste = cement + water Setting is mainly caused hydration of C3A and C3S together with C2S Accompanied by increase in temperature (heat)
Type of Setting Initial set – corresponds to rapid rise of temperature Final set – corresponds to the peak temperature/strength False set – sometimes occurs within a few minutes of mixing with water, no heat is evolved, concrete can be remixed
Cont. Flash set – caused by the rapid reaction between C3A and water Prevented by the addition of gypsum
Setting Time For OPC and RHPC: – Initial setting time – not less than 45 minutes – Final setting time – Not more than 600 minutes
Setting time is affected by: temperature and relative humidity
SOUNDNESS It is important that the cement paste, after setting, does not undergo a large change in volume i.e. expansion Expansion may occur due to reactions of free lime, magnesia, and calcium sulphate Cement exhibits expansion is classified as unsound Can be determined by Le Chattelier test
STRENGTH Strength test is not made on neat cement Two methods: – Mortar test – Concrete test
Mortar Test Mortar = cement + sand = water Mass of water = 10% of the mass of the dry materials Sand – standard sand, one size, spherical shape Cube size of 71 mm Materials are mixed and compacted using vibrating table
Cont. After 24 hours demould the mortar cubes and cure in water until the day of test Average of three samples According to MS 522: Pt. 1 – OPC – 23 MPa at 3 days
41 MPa at 28 days – RHPC – 29 MPa at 3 days
46 MPa at 28 days
Curing Tank
CONCRETE CUBE Concrete = cement + aggregates + water W/C ratio : 0.6, 0.55, 0.45 Cube size of 100 mm Preparation procedures are the same as mortar test – OPC – 11.5 MPa at 3 days
26 MPa at 28 days – RHPC – 18 MPa at 3 days
33 MPa at 28 days
Thank You
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