Particle size distribution and specific surface area of SCM's compared through experimental techniques

Supplementary cementitious materials (SCMs) are mainly used to produce a green concrete. To reach that goal effectively, it is highly important to adequately characterize the SCMs. It is well known that particle size distribution (PSD) and fineness of SCMs have a great influence on concrete properties. Traditionally, cement fineness has been assessed by the specific surface area (SSA) through the Blaine method (BM). However, the BM has the simplification of considering ideal spherical shape particles. The BET theory has also been used to calculate SSA, however, also some assumptions may lead to inaccuracy in the calculations. Both PSD and SSA can be evaluated through Laser Diffractometry (LD), but this technique also considers ideal spherical particles as a simplification. Regardless of the mentioned drawbacks, these techniques provide useful information to characterize SCMs provided that the limitations are considered. In this paper, Ground Granulated Blast Furnace Slag (GGBFS), Natural Pozzolan (NP) and Limestone Powder (LP) are tested using the BM, LD, and nitrogen adsorption. Particle texture and shape are assessed through petrography and scanning electron microscope (SEM). Results from BM, BET and LD are compared, analysing the possible effects of particle shape and texture