Carbon dioxide is the most important and abundant gas among all GHGs which have the highest contribution in global warming phenomenon. Thus, finding promising approaches to mitigate CO2 emissions is the priority of studies to subside the threat of climate change.
Cement industry is one of the major industry where more CO2 is released. This lead to find different ways to reduce percentage of CO2 released from this industry. In the following process they found different ways to produce green cement with less release of CO2. Few ways are as follows.
1) by replacing relatively large quantities of the cement with fly ash, and by using types of cement that require less energy to produce.
2) new types of concrete that reuse some of the concrete industry’s own residual products, such as stone dust from the production of crushed aggregate, and concrete slurry from washing concrete mixing plants and trucks
3) reuse residual products from other industries, such as ash from the combustion of sewage sludge and biofuels.
Properties of Green Cement
Setting Time
The test was carried out in accordance to IS4031 (part 5)1988
| Cement type | Initial Set (h:min) | Final Set (h:min) |
| OPC of 53 grade | 2:30 | 5:12 |
| SF4 (sodium hydroxide activated with 60 % slag, 40% fly ash) | 0:25 | 1:25 |
Advantages of green Cement
- Green cement reduces the water consumption – 50% in manufacturing stage, 20% at usage level (in concrete)
- Prevention of leaching of heavy material – When Fly ash is used in cement, it encapsulates heavy material in matrix of concrete.
- Reducing the need to mine Virgin Materials, reduction in mining activities, thereby enhancing the life of the limited National Limestone Reserves
Comparison between Green and Normal Portland Cement
| Property | Specification | Façade quantity |
| Unit weight | 2275 kg | 1590kg |
| (normal concrete) | ||
| 1-Day strength | 15MPa | 14.5MPa |
| 28 DAYS | 30MPa | 34MPa |
| Slump | 75mm | 50mm |
| Density | 2400 kg/m3 | 1750kg/m3 |
Example to Show it is good in Practice
In partnership with the Danish Road Directorate, the green solutions were tested in a new road bridge, which was completed in 2002. The bridge stands as tangible proof that the green types of concrete can be used in practice.
References:
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCHTECHNOLOGY
Properties of Green Cement Concrete with Alternative Cementicious Binders by Narender Reddy*, D.V.S.P.Rajesh
https://www.cii.in/greensummit2011/speaker/kn-rao.pdf
