Assignment 1:
Topic 1: Type of Cement
Introduction:
Cement is a fine mineral powder manufactured with very precise processes. Mixed
with water, this powder transforms into a paste that binds and hardens when
submerged in water. Because the composition and fineness of the powder may vary,
cement has different properties depending upon its makeup. It is also vary type of
cement depends on the purpose of used.
Portland cement is the basic ingredient of concrete. Concrete is formed when
Portland cement creates a paste with water that binds with sand and rock to harden.
Type of Portland cement:
1. Ordinary Portland cement (OPC)
2. Rapid Sulphate Hardening Portland Cement (RHPC)
3. Sulphate Resisting Portland Cement (SRPC)
4. Modified Portland Cement (MPC)
5. Low heat Portland Cement (LHPC)
6. Portland Blastfurnace Cement (PBC)
7. Portland Pozzolan Cement (PPC)
8. Colourded Cement
9. Coloured Cement
10. Others
There is common materials used to manufacture cement include limestone, shells,
and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and
iron ore. These ingredients, when heated at high t emperatures form a rock-like
substance that is ground into the fine powder that we commonly think of as cement.
Sulphate Resisting Cement (SRC)
Sulphate Resisting Cement is blended cement designed to improve the performance
of concrete where the risk of sulfate attack may be present. It also provides improved
durability for concrete in most aggressive environments, reducing the risk of
deterioration of the structure and structural failure. A properly designed concrete for
use in aggressive environments needs to have an appropriate cementitious content, a
low water: cement ratio, and be well compacted and cured. It is recommended that
specialist advice be obtained during the project design stage to ensure that the
concrete is adequate for the expected service.
Ordinary Portland cement is also susceptible to the attack of sulphate, in particular
to the action of magnesium sulphate. Sulphates react both with the free calcium
hydroxide in set cement to form calcium sulphate. While free calcium hydroxide can
also react with hydrate of calcium aluminate to form calcium sulphoaluminate at
about 227% of the exact volume aluminates. It results of the expansion within the
framework of hardened cement paste cracks and subsequent disruption. This
phenomenon is known as sulphate attack. A concrete designed to provide improved
sulfate resistance should have greatly reduced permeability, which should also
PAT 204 โ CONSTRUCTION MATERIALS
KENT FAN CHIAO TUNG
(151332377)
