PEMANFAATAN ABU VULKANIK GUNUNG KELUD SEBAGAI SUBSTITUSI SEMEN PADA PEMBUATAN MORTAR
SUPRAPTO, Prof. Ir. Imam Satyarno, ME., Ph.D.
2015 | Tesis | S2 Teknik Sipil-
The number of active volcanoes in Indonesia has the potential to produce abundant volcanic material and it can be utilized as material goods for building materials, one of them is volcanic ash. Kelud eruption that occurred on February 14, 2014 engulfed the city of Yogyakarta in thick volcanic ash material with the thickness of ± 5 cm and until the research was conducted, the ashes still an unused material and has not been utilized. Previous studies have mention that volcanic ash can be used as a pozzolan to reduce the amount of the cement so to reduce the cost of production of Portland cementbased building materials. This research was conducted to determine the chemical composition of the Kelud volcanic ash as well as to assess the effect of the mixture between volcanic ash and lime as a cement substitute in mortar manufacturing. The testing of the pasta is conducted to obtain the substituents composition such as lime and volcanic ash with a variety of weight ratio to obtain the most optimal composition. Mechanical behavior such as compressive strength, tensile strength and water uptake assessed from several cement substitution variations of 0%, 20%, 40%, 60%, 80% in the mortar manufacturing. A mixture of cement and sand mortar made with three (3) volume ratio variations 1S: 2P, 1S: 4P and 1S: 6P. Cube test specimens 50 mm x 50 mm x 50 mm for compressive strength testing for 7 and 28 days of specimens, and the water absorption testing for 28 days of specimens. The test specimen 75 mm x 50 mm x 25 mm for tensile strength testing for 28 days of specimens. Mortar workability test is conducted by using a flow table so the water cementious ratio will follow the scatter values between 70% - 115%. The chemical composition of volcanic ash contained in Kelud in the value of SiO3 + Al2O3 + Fe2O3 of 90,485% greater than 70% so that the volcanic ash meet the requirements of ASTM C618-03 as pozzolan N Class. The result of pasta test is the mixture of lime paste and volcanic ash weight ratio with the composition of lime : volcanic ash 20% : 80% as the most optimal ratio with the highest compressive strength at day 14 of 2,563 MPa. Mortar compressive strength at the day 7 and day 28 tend to decrease in the cement substitution composition, and it's getting larger. Tensile strength at day 28 also tend to decrease in the substitution composition, and the expanding is also applied. Water absorption mortar 10 minutes and 24 hours at a maximum of 11.98% to meet the requirements of water absorption in PUBI 1982 and SNI 03-0348-1989 with a maximum water absorption brick by 25% and 35%. Keywords : volcanic ash , lime , mortar , compressive strength , tensile strength , water absorption
Kata Kunci : volcanic ash , lime , mortar , compressive strength , tensile strength , water absorption
