Portland Cement Research Paper

1. Introduction
The environmental impacts of ‘greenhouses’ especially CO2 has been well understood to be one of the major contributors to climate change. Contributing to 4.5% CO2 emissions globally from Portland cement production, there is an urge to push towards the minimization of CO2 emissions through developments of a sustainable and environmentally-friendly alternative to Portland cement.i Considering the immense volume of usage globally for Portland cement and its environmental impact, this serves as a necessitation for such developments. Portland cement is used as one of the most fundamental binding material for construction, such alternative material should therefore have the same binding properties possessing the resilience, resistance

‘Geopolymer’ is essentially a material which falls under the category of ‘alkali-activated material’ whereby it is developed from little or no calcium aluminosilicate species activated by an alkaline, usually fly-ash based or metakaolin.ii The reaction, to put simply, is the polycondensation of aluminosilicate molecules into larger units that is continuous and chain-linked, a structure analogous to that of a polymeric thermoset. iii
The microstructural evolution of AAM depends mainly on the content of the binder system. One key parameter or content that dictates the dominant gel structure is the calcium content. Little or no calcium content within the system would lead to a formation of an ‘alkali aluminosilicate’ or ‘N-A-S-H’-type gel and on the other hand, high calcium content binder systems would lead to ‘calcium (alumino)silicate hydrate’ or ‘C-A-S-H’-type gel.ii Geopolymers, as said above are AAM that contains little or no calcium so AAM such as pulverized fly-ash or metakaolin dominantly have N-A-S-H-type gel.vi It is on this basis that the N-A-S-H-type gel have been referred to as ‘geopolymer’

There were severe damp patches on parts of the tile during a standardised water ponding test. This problem was seen to be very critical simply due to the requirement that a roofing tile, fundamentally, must be impervious to water from all sorts of precipitation such as rain or snow. This problem can be implied to be rooted within the gel structure of PFA-based geopolymer upon activation. The microstructure of alkali-activated PFA is dominated by the ‘geopolymer gel’ or the N-A-S-H-type gel (or alkali aluminosilicate-type gel)vi and these type of gels are attributed to the low calcium content in the AAM