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Climate change influences urban conditions on the north coast of Java island causes changes in coastlines and catastrophic tidal flooding that harmed infrastructures, i.e. cracks, tilts, and sank, and damage on roads and waterways. Semarang is one of the cities that always experiences flood problems; it reduces bearing capacity due to the swelling-shrinking and consolidation behaviour on unconsolidated clay materials. This research was intended to reveal the changes in the soil properties due to seawater contact. The method used was the immersion model and mineral composition of XRD results. Statistical tests were conducted on the immersion and mineral composition results to obtain correlations between seawaters and changes in clay soils. The F-count value of 3.897 is more significant than F-table, indicating clay soil is strongly influenced by seawater. The statistical test resulting in the clay minerals and volume changes show the t-count value of the Montmorillonite has a value of 3.303 or greater than the t-table value. Hence, the Montmorillonite has the most influence on changes in sample volume when immersed in seawater. This research is expected to provide an understanding of the seawater impact on clay, building, and infrastructure in Semarang city. [ABSTRACT FROM AUTHOR]

Buton asphalt is one of the largest natural asphalt deposits in the world. The Asphalt-bearing rocks in Buton Island are calcarenite limestone, bioclastic limestone, and crystalline limestone. This research aims to determine the relationship between asphalt-bearing rocks and asphalt quality. This research uses several methods the soxhlet extraction method to determine bitumen and water content, XRF analysis to determine the chemical content of asphalt, and petrographic observations to determine rock composition and rock porosity. The result shows that, in general, the quality of the asphalt-bearing rocks was influenced by their porosity. With the increase of the porosity of the asphalt-bearing rocks, it will be easier for asphalt liquid to penetrate the rocks. The greater porosity of the rocks will produce the higher quality of the asphalt. The asphalt-bearing rock in the research area with the best bitumen quality is calcarenite limestone, which has the highest porosity level. [ABSTRACT FROM AUTHOR]

Due to development of infrastructure in some regions of Indonesia, existing cement producers are expanding their capacity and new investors began to build new factories as well. Portland cement is the most commonly produced cement in Rembang area, mainly using limestone (CaCO3) mixed with additional material clay, shale, sand as source of alumino-silicate. This study aims to evaluate quality of sedimentary rocks from Ngrayong Formation in Gunem District as additional material in cement industry. Detailed field mapping and rock sampling are used to determine lithology types of study area, supported by petrographic analysis. Geochemical XRF analysis aims to determine chemical composition of rock samples as standard parameter for material quality. Lithology of study area is sedimentary rocks composed of layers of quartz sandstone, siltstone, and claystone with slightly to completely weathered. This study uses company chemical standard SiO2 > 65%, Al2O3 > 16.5%, and SO3 < 2.5% for rocks. Result of geochemical concluded that quartz sandstone in the western part of study area and claystone meet the aforementioned standard as additional material for cement mixture. Other rocks are unsuitable as they can damage manufacturing equipment as well as compromise the final cement quality. [ABSTRACT FROM AUTHOR]

Bintuni Basin is a foreland basin located in the Bird's Head of Papua. There were three fields observed in this study, namely Alpha, Beta and Charlie. The subsurface data indicated a mismatch of the order of hydrocarbon maturity in the three fields. This study aimed to explain the causes of incompatibility of the order of field maturity with the concept of generation-migration. The methods which were used in this study were 2D field-scale basin modelling on two seismic lines for subsurface observation, then calibrated to several geochemistry evaluations. Based on the results of source rock analysis, Bintuni Basin has two source rocks, Aifam group and Kembelangan Bawah Group, both of them are gas prone. The accumulated hydrocarbons in the Alpha field leaks into shallower sedimentary layers and do not migrate laterally due to the low clay factor and the distant trap height. The existence of lateral migration is caused by a sloping trap height. From the result of the research, it can be concluded that each field are filled by different charge focus from different migration route. Therefore, there is no correlation between three fields, including the maturity of the hydrocarbon accumulated, other than generated from same source rocks. [ABSTRACT FROM AUTHOR]