Development of Interlock Bricks with Eruption Ash of Mount Sinabung as One of Its Constituent Materials

Mount Sinabung, located in Karo district, North Sumatra, Indonesia is one of the active volcanoes in Indonesia. The eruption of Mount Sinabung produces volcanic smoke and dust. The last eruption that occurred on Friday, 6 April, 2018 with column of ash height more than 5 meters and hot clouds glide as far as 3.5 meters to the southeast. Almost four subdistricts in Karo district affected by the eruption which erupted volcanic ash as far as 5 kilometers and still in standby IV category until now. The number of volcanic ash pile from the eruption of Mount Sinabung has become an environmental problem and has harmed the surrounding community. In this research, volcanic ash from the eruption of Mount Sinabung will be used as a mixture of Interlock concrete bricks with mixed variations of 0%, 10%, 20%, 30%, 40% and 50%. Volcanic ash sieved with no. 2000 will be substituted as constituent material of Interlock concrete bricks making, hoping it can increase concrete strength. Tests include are form testing (visual), size, absorption and compressive strength test. From the results, it showed that volcanic ash had an effect on the strength of concrete bricks, where in normal bricks, there was compressive strength of 0.74 KN / cm2 (7.40 Mpa) with 12.19% of water absorption. Had an increased by 1.20 KN / cm2 (12.10 Mpa) in 20% variation, with water absorption of 14.56% and decreased by 0.81 KN/cm2 (8.10 Mpa) with absorption rate of 13.53% at 30% variation. For the cube sample, its strength reached 23.2 MPa and water absorption as much as 7.49% with mixture variation of 20%. The results are eligible on SNI 03-0349-1989, for hollow concrete brick wall pairs and included in the quality I classification with compressive strength of ≥ 7 MPa and water absorption of ≤ 25%.