| dc.description.abstract | The fly ash from oleochemical industry waste in Medan has been evaluated
for producing brick. The fly ash was used to replace the use of cement in the brick
after mixing with gypsum. Firstly, the characteristic of the fly ash was investigated by
analyzing its chemical composition by gravimetric methods, heavy metals analysis
such as Zn, Pb, Cd, Cr, Cu was investigated by atomic absorption spectrometry, and
the mineralogical composition was determined by the powder XRD and XRF
technique as well as analyzing particle size. The optimization of the components in
the brick was achieved by varying determined component while the other components
kept constant by the manufacturing of mixed specimen with two stages. First. the
determination of the optimal percentage of gypsum addition by adding variation 0% -
20% with interval 2%. Second, cement substitution by fly ash in adding variation 0%
-30% with interval 5%. Characteristics test of the dried specimens performed on days
3, 7, 14, and 28. Type of testing such as density, water absorption, porosity,
compressive strength, split tensile strength, morphology (SEM) leaching test as well
as thermal properties (TGA). It was obtained the optimum composition of gypsum
was 16% and the optimum composition of coal fly ash substitution of the cement was
25% which resulted compressive strength 80.398 kg/cm2
, split tensile strength 25.13
kglcm2
, percentage of water absorption 11. 982%, and porosity 0. 022%. Analysis of
morphology (SEM) showed that this brick specimens have a uniform surface without
any agglomeration and uniform pore distribution, while the thermal analysis (TGA)
showed that the specimen is slightly decreased thermal resistance compared to
cement by the residual value of90.56% at temperature 80(fC. Leaching test showed
the heavy metals level of Cadmium (Cd) in curing water of the concrete blocks above
the specified threshold levels ie 2.1134 mg IL, while the levels of lead (Pb) of 1.6552
mg I L was below the set threshold while Cr and Zn were not detected. The results
showed that oleochemical industry fly ash can be used as substitute material in the
manufacture in 2"'1 quality solid brick in accordance with SNI 03-0348-1989 seen
from the compressive strength and the percentage of water absorption. | en_US |
