| Summary: | Carbide waste is a by -product in the acetylene production process from
calcium carbide. Carbide waste is classified as hazardous waste. The carbide
waste must be managed properly otherwise will cause an environmental pollution.
This study aims to determine the possible use of carbide waste as substitute
material of sand to produce solid concrete brick. Concrete brick were tested for
compressive strength capacity, water absorption test as well as concentrations of
heavy metals Zn and Cu in the leachate.
Carbide waste stabilization process was carried out by mixing the waste
with the materials composing concrete brick. By doing this methode, it would be
expected to reduce the solubility and the spread of hazardous and toxic materials
contained therein into the environment. Volumes of mortar used were 4.5 liters
and 6 liters. The composition of the volume of cement and sand used was 1:6 and
1:7, with a variation of the sand substitution by the carbide waste with
percentation of 16.67% - 66.67% and 14.28% - 71.43%. The spread of hazardous
and toxic substances contained in carbide during soaking was modeled by
diffusion in a slab.
results using mortar volume of 6 liters for the compositions Experimental
1:6 and 1:7 with variation of the sand substitution by the carbide waste at 33.33%
- 50% and 42.86% - 57.14% showed results that the larger the sand substitution by
carbide waste produces the smaller compressive strength. These results, however,
still meet the SNI standards. Porosity of concrete bricks produced ranged from
14.3% - 28.9%. From the mathematical model obtained the percentage of Zn and
Cu metal that comes out with leachate after soaking for 11 years was 74%, but the
lab verification gave better than model predictions. Release of Zn and Cu in the
leachate has not been detected by the analytical instrument (<0.02 ppm). This
figure is equivalent to less than 0,67% leaching. This is due to the fact that Zn and
Cu ions are not in their free element. The results from this study showed that the
carbide waste can be used as a substitution material of sand on solid concrete
brick production.
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