Blended Cement Case Study

2.3 Blended Cement

The first effort to manufacture more environmentally friendly concrete was producing concrete with blended cement. Proposals have been put forward into formulation ‘blended cement’ where products such as pozzolans are added to OPC with the purpose of decrease the environmental effects of concrete. Generally, a part of OPC is replaced by by‐products from other industries, for instance, fly ash or ground blast furnace slag (GBFS). Chindaprasirt (2008) reported that annually just in Thailand, 4 million tons of fly bottom ashes are releasing into the environment. (Mehta, 1998) reported that the less than 50% of this fly ash is used in the concrete industry as a pozzolanic material in order to lessen the heat of hydration and enhancing the workability and durability properties. Normally, a ratio of the fly ash substitution with OPC is not as much as 40% of the mass of cement (Mehta, 1998).

Damtoft et al. (2008) concluded that using Portland cement has a significant impact on the environment and suggested techniques by which these environmental impacts of manufacturing concrete can be reduced:

• The addition of extra materials to the list of approved supplementary cementitious materials (SCM’s) within current

The type of application of geopolymeric materials is determined by the chemical structure in terms of the atomic ratio Si:Al in the polysialate. According to Davidovits (1994), he classified the type of uses according to the Si:Al ratio as presented in Table 1. A low ratio of Si: Al of 1, 2, or 3 starts a three dimensional-Network that is very rigid while Si: Al ratio higher than 15 provides a polymeric character to the geopolymeric material. For many uses in the civil engineering field, a low Si: Al ratio is