Chemical soil stabilization is known as the most economical method compared to others. The development of stabilization materials has led to studies of the utilization of natural materials and waste materials to replace cement and lime which has become the most popular binder agent ever known. This research utilizes natural minerals such as overboulder, zeolite and Palm Oil Fuel Ash (POFA) as its binder agents. The amount of natural material varies at intervals 3% - 15% by the weight of soil. Additional of natural materials is done to increase bearing capacity as a subbase layer, which is based on FHWA standards CBR minimum is 20%. California Bearing Ratio (CBR) tests were carried out to see the effect of each material for increase bearing capacity of soft soil. Curing periode is varies at 7 days, 14 days and 28 days. The results shows, by adding natural minerals such as overboulder, zeolite, and POFA increasing the CBR value up to 5 times, 6 times and 5 times compared to untreated soil and close to the CBR value of cement stabilized soil. Referring to FHWA standards, we can conclude that natural materials can be used for stabilization materials on subbase layer.

South Sulawesi is one of eastern Indonesia area covered with coastal line which have growth fast of industries. Infrastructure builds and developed in a row of industries population. Most coastal are lowland areas with expansive soil as primary soil forms. Exhaustive laboratory test conducts for clay taken from lowland area in south Sulawesi and lime up to 10% and volcanic up to 25% as stabilizers to know the Physical-mechanical properties and mineralogical when the expansive soil stabilized. The extensive soil stabilized with 5% lime + 15% Volcanic ash presents better performance and pass the roadbed materials requirements. Chemical reactions between soil and the stabilizers increase the pH and electrical conductivity. X-ray diffraction (XRD) and transmission electron microscope (TEM) confirmed new cementing agents’ findings regarding the results of chemical reactions. An explicit effect on controlling the soil deformation and the moisture change shows by the expansive soil stabilized with 5% lime + 15% volcanic ash. The research results find the optimum combination of stabilizers to reduce cost to improve expansive soil from the South Sulawesi lowland area.

For several decades, lightweight material applications have been extensively studied. Modifying various types of soil with EPS beads or lightweight geomaterials is an alternative construction material on site that can reduce excessive problems such as large deformation and lateral pressure. This study aims to examine the strength characteristics of lightweight geomaterials, namely lightweight modular block/LMB. LMB is composed of EPS beads, dredged soil, and cement. The cement amounts are 3%, 5%, 7%, and 9%, with EPS variations of 0.5% and 0.75% to the mixture weight. Laboratory tests were conducted to investigate the strength with unconfined compression and undrained direct shear tests. Before testing, the specimens were made using the one-layer static compaction method and were cured for 7, 14, and 28 days. This paper also presents explanations related to the specimens making and treatment by providing preliminary test results to compare the effectiveness of the three-layer and one-layer methods. Moreover, the curing treatments to avoid cracking were explained explicitly. The result shows linearity between both increasing the amount of cement and adding more curing time to the increase of the strength parameter. In contrast, adding more EPS decreased the strength, but adding cement helped increase the strength parameter with a remarkable value at C7% and C9%. Increasing the amount of EPS also reduced the density of the mixture by 18%–29%. Doi: 10.28991/CEJ-2023-09-03-014 Full Text: PDF

Changing material into a lightweight geomaterial such as EPSCS is one of the considerable methods to improve the geotechnical performance in the field. This material is already used in numerous construction projects due to its light characteristics. Lightweight Modular Block or LMB is a type of EPSCS composed of dredged Soil, cement, and Expanded Polystyrene (EPS). The amount of cement composition are 3%, 5%,7% and 9%. Meanwhile, Expanded Polystyrene (EPS) are 0.5% and 0.75%. This paper aims to briefly explain the performance of LMB as road foundation materials, such as subbase and base, through CBR laboratory tests. Based on the data, adding EPS can reduce density by 18% - 29% depending on the chosen mixture. Whereas adding more cement tends to increase the CBR value. All the test results will be analyzed and compared to SNI 03-3438-1994 for its qualification as a road foundation layer.

Material with high strength but has the lightest density that can be tolerated is the main purpose of doing a research about soil improvement. This research aims to develop a lightweight geomaterial (LWGM) by substituting of the soft soil with Expanded Polysterene (EPS) which is stabilized with Waste of Buton Asphalt (WBA). The variation of the WBA used was 3%, 5%, 7% and 9%, while the variation of the EPS used was 0.15% and 0.30%. Curing of the specimens was carried out for 7 and 28 days to see the effect of curing on the pozzolanic reaction to the specimens strength. The test results shows that soil substitution with EPS reduce the density by 10% - 25%. Even though it decreased comparing to the strength of the sample without additional of EPS, the CBR and UCS LWGM values are still classified as good performance and can be tolerated. Based on the results of curing samples, during the curing period of 7 days, the CBR value increased up to 5 times at 0.15% EPS and 4 times at 0.30% EPS. Meanwhile, during the 28-day curing period, the CBR value increased up to 10 times at 0.15% EPS and 6 times at 0.30% EPS. Meanwhile, the UCS value after curing 7 days is 12 times - 48 times and after curing 28 days is 15 times - 63 times greater than untreated soils.