GEOPOLYMERISATION OF VOLCANIC MUD
This paper presents the results of geopolymerisation of volcanic mud. The mud is taken from a mud volcano in Sidoarjo, East Java, Indonesia; and thus, locally it is called Sidoarjo mud or LUSI mud. The mud volcano started to erupt since May 2006, and to date there is no sign that the eruption will end in the near future. Currently, the daily discharge of mud is about 30,000m3. More than 640 hectares of productive land, housing and industrial areas, and infrastructural facilities have been submerged. The height of the cover dam right now is not less than 12.00 meters. The mud is rich in SiO2, Al2O3 and CaO. In its original form, its microstructure is crystalline. The SEM results revealed that the mud has plate-like shape, dominated by particles with less than 20μm in dimension. The total amount of SiO2, Al2O3 and CaO is more than 80%, with SiO2 content about 57% and Al2O3 about 23%. After pre-treatment in the form of calcinations and grinding, the mud is proven to be a potential raw material for geopolymer. In this study, a combination of sodium hydroxide solution and sodium silicate solution is used as the alkaline activator. The particle size of the calcined mud affects the reactivity of the material, whereby the finer the particle size, the higher the compressive strength of the geopolymer. The compressive strength of volcanic mudbased geopolymer mortar at 7th day is more than 30 MPa.