Improved pozzolanic activity of sugar cane bagasse ash by selective grinding and classification

Selective grinding was identified as a potential technology to reduce the content of quartz in sugar cane bagasse ash (SCBA), so as to assist in developing an improved supplementary cementitious material. The selective grinding strategy comprised of a ball mill and two classifiers, where a quartz-rich waste is discharged as a coarse waste by the first one. The amenability of two distinct SCBA samples to selective grinding was first demonstrated on the basis of measurements of strength of individual particles. The samples were then analyzed with respect to chemical and mineralogical compositions and pozzolanic activity. Results showed that the quartz content decreased significantly as a result of selective grinding and classification, thus increasing the amorphous content and, consequently, the pozzolanic activity for both of the studied SBCA samples. Moreover, good correlations were observed between the amorphous content and SCBA reactivity considering electrical conductivity and pozzolanic activity index tests.