Cement Explained

Which Cement Should I Use?

This depends entirely on the application. Below is a guide to mixing ratios.

		Cement	Sand	Aggregates
Very Low Strength Mix	5 MPa	1	6		Brick Laying (Mortar) and Plastering
Low Strength Mix	10-15 MPa	1	4	4	Domestic Foundations and Footings, un-reinforced concrete floors, Block Making
Medium Strength Mix	20-25 MPa	1	3	3	Driveways and un-reinforced industrial floors
High Strength Mix	25-30 MPa	1	2.5	2.5	Reinforced Concrete, Structural Applications e-g. Suspended Slabs, Columns, Beams
Ultra High Strength Mix	35 MPa	1	2	2	Watertight Concrete

All the Portland Cement we sell an be used in the above mixing recipes, what changes depending on the cement is the curing time.

Things that can affect the strength and quality of your concrete:

• Type of Sand Used: coarse river sand is recommended for all concrete, finer grain sand can be used for plastering/mortar.

• Cement-Water ratio: too much water produces weak concrete and too little water reduces the workability.

• Compaction:  Any entrapped air resulting from inadequate compaction will lead to a reduction in strength. If there was 10% trapped air in the concrete, the strength will fall in the range of 30 to 40%.

• Curing: Concrete should be kept hydrated and not allowed to dry out during the first couple of weeks.