Characterization of PCC Cement by Addition of Napa Soil from Subdistrict Sarilamak 50 Kota District as Alternative Additional Material for Semen Padang

The study has been conducted to determine characteristics of the portland composite
cement by the addition of napa soil from Sarilamak subdistrict, 50 Kota District as an alternative
additional material at PT. Semen Padang. Napa soil is a natural material highly containing silica
and alumina minerals so that it can be one of material in producing cement. This study aims to
determine the effect of napa soil on the quality of portland composite cement. Napa soil used in
the variation compositions 0%, 4%, 8%, 12% and 16%, for control of cement used 8 % of
pozzolan and 0 % of napa soil. Determination of cement quality by testing cement characteristics
include blaine test, sieving, lost of ignition or LOI, insoluble residue, normal consistency, setting
time and compressive strength. Cement was characterized using XRF. Fineness of cement
decreases with the addition of napa soil. Lost of Ignition of cement decreased, while the insoluble
residue increased with the addition of napa soil. Normal consistency of cement increasing, so
does initial setting time and final setting time of cement. While the resultant compressive strength
decreases with the addition of napa soil on 28 days, 342, 325, 307, 306, and 300 kg / cm2.