Advanced Construction Material - Micro Silica In Concrete
Micro silica is an amorphous type of silica powder mainly collected in the baghouse filters as a byproduct of silicon and ferrosilicon production. The paper summarizes the important physical and chemical properties of micro silica and uses those results for a safety and environmental (HSE) micro silica assessment. The micro silica consists of spherical particles having an average particle size of 150 nm and a specific surface area of typically 20 m 3 / g. The chemical and physical properties of this inorganic product are different compared to other amorphous and crystalline silices. More than 500,000 MT of micro silica are sold to the construction industry worldwide and are used in fiber cement, concrete, oil well drilling, refractories and even in polymers.
Micro silica contains traces of heavy metal oxides and organic deposits, which originate from natural raw materials. Since the concentration of these impurities is very low, micro silica complies with company policies and international regulations. Traces of crystalline silica in micro silica do not appear to pose a health risk, either for silicosis or for lung cancer, due to low levels and large particle size. According to the International Agency for Research on Cancer (IARC), there is insufficient evidence for the carcinogenicity of silica smoke, in contrast to crystalline silica. In order to assess the potential health risks of micro silica and compliance with international regulations from the point of view of a occupational hygienist, fragments of information from different analytical techniques should be collected. Putting together these fragments results in a cohesive picture. All evidence indicates that micro silica is not a dangerous product when applied as advised.