PENGARUH TINGKAT KEHALUSAN ABU SEKAM PADI SEBAGAI BAHAN SUBTITUSI PARSIAL SEMEN TERHADAP NILAI KUAT TEKAN MORTAR
Besides producing rice, rice also produces rice husk. The largest waste in the rice milling process is rice husk, usually obtained about 20% - 30% of the grain weight while the other yield is between 8% - 12% bran. The remaining combustion of rice husk in the form of rice husk ash has a high silica content, which is 94 - 96% (Houston, 1972). The high silica oxide (SiO2) content gives good pozzolanic properties in rice husk ash so that it can be used as a partial substitution material for cement. The variables in this study were in the form of compressive strength testing with cube-shaped specimens measuring 50 mm x 50 mm x 50 mm. The rice husk ash to be investigated as a partial substitution of cement is ash that passed the no.200 filter and refined it so that it becomes the level of fineness of zone 0, zone I, zone II, and zone III. The percentage of rice husk ash substitution used was 0%, 5%, 15%, and 25%. Mortar compressive strength was tested at 7, 14 and 28 days. The optimum level of substitution of rice husk ash to cement is 5% with the highest compressive strength at 28 days at 25.2 MPa. The best level of refinement is the zone III subtlety with a mortar age of 28 days which results in compressive strength of 25.2 mpa. The higher the percentage of use of rice husk ash, the compressive strength produced will be lower.