I am working in concrete fieled practice and i would like to know more about the cement and microsilica, that is my concern.
Cement is made by heating limestone [CaCO3] with small quantities of other materials (such as clay) to 1450°C in a kiln, in a process known as calcination. The resulting hard substance [CaO], called 'clinker', is then ground with a small amount of gypsum [MgSO4.2H2O] into a powder to make 'Ordinary Portland Cement', the most commonly used type of cement (often referred to as OPC). Portland cement is a basic ingredient of concrete, mortar and most non-speciality grout. The most common use for Portland cement is in the production of concrete. Concrete is a composite material consisting of aggregate (gravel and sand [impure SiO2]), cement, and water. As a construction material, concrete can be cast in almost any shape desired, and once hardened, can become a structural (load bearing) element. Concrete consists of highly insoluble calcium silicates (CaO+ SiO2 -> CaSiO3). Now silica is pure SiO2 and so finely grounding it and putting into the concrete mixture instead of more coarse sand almost certainly results in a better product with better mixing and hence a stronger cement. This is an educated (I hope!) guess by an inorganic chemist. Cheers, dr p
