The importance of cement and concrete

Paul Mugabi writes about why cement and concrete are some of the most important things to consider when it comes to building both residential and commercial houses

Cement is a water-based binder used to bind other building materials together. It is used in the production of mortar and concrete during the construction process. Concrete on the other hand, is a material used in construction, made by mixing aggregate (i.e. different types of sand and gravel), cement, small stones and water.

The reason cement is one of the most common construction ingredients among other is its ability to hold the structure together. To get concrete, one mixes water, sand and gravel. When cement is mixed with water and sand, the outcome is cement plaster, yet when cement is mixed with water, lime and sand, the result is mortar.

The word cement has become such a natural part of construction vocabulary that even individuals who very remotely relate to modern construction processes make glib references to the substance.

According to, a story titled The History of concrete and cement, states that, Mr John Smeaton, a British engineer made the first modern concrete (hydraulic cement) in 1756, by adding pebbles as a coarse aggregate, and mixing powdered brick into the cement. Later though, in 1824, Mr Joseph Aspdin, the English inventor, created the first true artificial cement by burning ground limestone and clay together; a process that changed the chemical properties of the materials, creating stronger cement than what plain crushed limestone would produce. He also invented Portland cement, which to date dominates concrete production.

Why it is popular
Most buildings (individual and commercial) use concrete because it is a strong element. Concrete solidifies and hardens after mixing with water and placement due to a chemical process known as hydration. The water reacts with the cement, which bonds the other components together, eventually creating a stone-like material.

The importance of cement and concrete

According to concrete is used to make pavements, pipe, architectural structures, foundations, motorways/roads, bridges/overpasses, parking structures, brick/block walls and footings for gates, fences and poles.

Also, concrete is used more than any other man-made material in the world. As of 2006, about 7.5 cubic kilometres of concrete are made each year, more than one cubic metre for every person on earth.

Cement types
The European norm standards which have been adopted by East Africa stipulate that there is a maximum of 27 different types of cement divided into five main types of CEM I, CEM II, CEM III, CEM IV and CEM V, each with a different strength class to serve different purposes in the construction process.

In Uganda, the Lafarge variety represented by Hima/Bamburi Cement has four types of cement on the market. Their brand names are Hima Multipurpose (CEM II 32,5N), Bamburi Supaset (CEM IV 32,5N), Bamburi Power Plus (CEM I 42,5N) and Bamburi PowerMax (CEM II 42,5N).

Cement applications
The differences are their strength properties, the components and their applications as outlined below.

Hima multi-purpose
Hima Multi-purpose is a Portland pozzolanic cement of CEM II type. Its strength class is 32.5N. It is composed of Portland Clinker (The major ingredient of cement and determinant of strength) and Natural Pozzolona (material that reacts with calcium hydroxide and alkalies to form compounds possessing cementitious properties).
This type can be applied in the following procedures;
• General purpose construction work
• Structural applications/Reinforced concrete suspended columns
• Beams and water retaining structures
• Domestic poles and post foundations
• Mortar and plaster
• Brick and block making

Bamburi Supaset
Bamburi Supaset is a Portland Pozzolannic Cement of CEM IV type. Its strength class is 32.5N. It is composed of Portland clinker and other constitutes (mainly Natural Pozzolona-material that reacts with calcium hydroxide and alkalies to form compounds possessing cementitious properties). It is used in the following areas of construction;

• General purpose construction
• Structural applications/Reinforced concrete suspended columns, beams and water retaining structures
• Medium strength concrete drive ways
• Light industrial floors
• Domestic poles and post foundations
• Mortar and plaster
• Brick and block making

Bamburi powerplus
This is a CEM I type cement with a high strength of 42.5N strength. It is cement in its purest form with up 95 per cent clinker composition and five per cent Gypsum (a very soft mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4

•2H2O used to control the setting time of cement. Gypsum is a component of all cements).

Bamburi powerplus is used in the construction of dams, bridges, soil stabilisation, water retaining structures, and foundations. Because it has high early age strength, it is the recommended cement for use in large constructions projects which require speed (fast track projects) and other high strength properties. It is the cement being used for construction of the Bujagali Dam currently. Its applications are;

• High rise buildings and infrastructure
• Bridges and dams
• Fast track construction projects
• Spun pipe manufacturing
• General concrete applications
• Post-tensioning and pre-stressing slabs beams
• Pre-cast manufacturing
• Medium strength concrete; concrete columns, suspended slabs, beams and water retaining structures

Bamburi powermax
Bamburi powermax is Hima Cements’ most recent addition to the market. It is a CEM II type cement with a high strength class 42.5N. Its applications are similar to those of PowerPlus since their strength class is the same. However, it gives additional benefits on improved workability and for the technical client- lower heat of hydration and reduced alkalis.



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