Page 46 - CAPE Green Engineering Syllabus 2016.docx_Neat

The significant amount of CO2 is produced during the calcination process.

Sources of CO2 and GHG emissions in the manufacturing of Portland cement are:

1. from calcinations of limestone and clay = ± 50 –55%;

2. from fuel combustion = ± 40 –50%; and,

3. from use of electric power = ± 0 –10%.

Limestone + Silica = Portland cement + carbon dioxide

(1450°C) (3CaO.SiO2) (2CaO.SiO2) + 5CO2
5CaCO3 + 2SiO2

a. The approximate % Composition of Ordinary Concrete

COMPONENT NAME %

Tri-calcium silicate C3S 15-25
Di-calcium silicate C2S 75-85

Tetra-calcium-alumino- 10-15
Ferrite C4AF

Calcium sulphate 1-4

Tri-calcium Aluminate C3A 7-10

Calcium Carbonate 0-5
Magnesium Oxide 0-3
Calcium Oxide 0-1
Chromates 0-0.005

4.0 Recommended Applications of different types of Cement manufactured by the TCL

All general purposes: Driveways, pavements and sidewalks, reinforced concrete buildings, bridges,
railway structures, tanks, reservoirs, culverts, precast concrete products, pipes and masonry units. TCL
claims that they are committed to the preservation of the environment and demonstrates
this through their operating procedures. As such they have implemented the ISO 14001:2004
Standard, an Environmental Management System, to which TCL has been certified in 2006.

4.1 Premium Plus Cement (Type IP) (Pozzolanic Cement)

In order to reduce the energy consumption as well as the greenhouse gas emissions, The Premium
Plus cement was launched in 2009. The Premium Plus cement is a typical cement replacement or
Pozzolanic admixtures or ‘pozzolans’, which contain reactive silica (SiO2), and sometimes also reactive
alumina (Al2O3). This product is a direct result of our commitment to continuous improvement and
environmental responsibility. In fact, Premium Plus allowed TCL to significantly reduce the level of
greenhouse gas emissions into the atmosphere, thereby reducing their carbon footprint. This cement

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