Pembuatan Batako dengan Menggunakan Lembah Abu Terbang Industri Oleokimia sebagai Bahan Pengganti Semen dengan Campuran Gypsum

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.