Materials Science Forum Vol. 998

Abstract: In remote areas, most roads still use pavements that are very sensitive to climate change, especially those using clay pavements with high plasticity. In addition to the issue of cost, the difficulty of obtaining a proper source of material is another problem that has led to soaring prices for materials. In this regard, a study was conducted using local materials, namely zeolite as a stabilizing material added with waterglass as activating agent. The research began with samples of laterite soil and natural zeolite for XRD test (microstructure testing), and then testing for laterite soil’s index properties and engineering properties, namely Unconfined Compressive Strength and CBR value. The purpose of the test is to determine the correlation between the Unconfined Compressive Strength (UCS) and the soil bearing capacity (CBR) caused by adding zeolite as stabilizer material and waterglass as activator with increasing curing time. Laterite soils contain a brownish red iron oxide. The stabilizing material zeolite contains a crystalline mineral of alumina silicate SiO₂. While waterglass composed of sodium meta silicate. Stabilization carried out by mixing 4%, 8%, 12%, 16%, and 20% of zeolite with addition of 2% waterglass, percentage was measured based on soil dry weight. Specimens were tested at curing time of 0, 7, 14, and 28 days. The test result shows increasing UCS and CBR values with increasing percentage of zeolite. At mix of 20% zeolite and 2% waterglass, the unconfined compressive strength reaches 23.54 kg/cm2 with CBR value 58% at 28 days of curing time.

Abstract: The main problem in infrastructure development at the soft clay was its bearing capacity therefore it needs to be improved. In this research, the improvement method was carried out by modeling in small scale of preloading and heat induction combination. Location of soft clay sampling was in Takalar, Indonesia. The purpose of this study was to investigate the change of the shear strength of soft soil corresponding with heat induction at the radial zone. The shear strength was obtained by vane shear test and compressive strength from unconfined compressive test (UCT). The heat applied ranging from 100^o C, 200^o C, 300^o C, and 400^o C with static preloading load 0.20 kg/cm². The strengths of the soil in radial zones have been tested at R0, R1, and R2. At lowest temperature 100° at R0 the compressive strength was 0.203 kg/cm2, at highest temperature 400° at R0 the compressive strength 0.467 kg/cm2, there was a significant increasing of compressive strength value with the change of temperature. At the highest temperature 400⁰ the shear strength from vane shear tests resulting at R0 0.240 kg/cm², R1 of 0.128 kg/cm², R2 of 0.077 kg/cm². At the lowest temperature of 100^o C shows R0 at 0.116 kg/cm², R1 at 0.070 kg/cm², R3 of 0.046 kg/cm². The results show a tendency of declining strength value as the soil farther away from center of heat induction. The experimental result from this model produces strength that can be used as a parameter of the foundation model on soft soil.

Abstract: The purpose of study was to determine the structure of the studied soil layer based on measurement of geo-resistivity with the Wenner configuration and geotechnical drilling method. Geotechnical drilling was one way of soil/rock investigations to determine the parameters soil layers. Based on the objective, field tests and laboratory tests were carried out to support scientific investigations. The results of measurements in the field using geo-resistivity were performed to a depth of 23 meters, resulted in 2 types of soil sediment layers namely clay and sand. At a depth of approx. 8 meters, the groundwater level was found and through laboratory tests, the results of geotechnical drilling gave 2 types of soil classification to a depth of 15 meters, i.e CH and ML. In general, the results of the geo-electrical and drilling tests represented the soil real conditions in developing the stratigraphy of the subsurface layer of the soil. It showed that in the first layer, the sediment layer resulting from the breakdown of the initial rock or sediment layer which had undergone transportation of sedimentary layers in the form of clay, silt or sand and did not experience compaction so that it has a large resistivity value. The next layer associated with regional geological maps are dominated by sand.