GEOMATE Journal

LATERAL SHRINKAGE OF COMPACTED POLYURETHANE-CLAY SUBJECTED TO A SINGLE WET-DRY CYCLE

2024-03-23T05:36:40+00:00

Compacted clay is often used as a sanitary landfill liner due to its impermeable characteristics. However, compacted clay is susceptible to shrinkage as the temperature changes, which may affect the permeability due to the development of shrinkage cracks. Thus, clay was mixed with polyurethane, a stable polymer, once the reaction was completed. The polyurethane-clay mixture was compacted wet of the optimum moisture content and monitored through several moisture contents using direct measurement of the specimen diameter by Vernier caliper. The study inferred that the ratio of the lateral shrinkage of the compacted polyurethane-clay mixture is significantly less than that of the clay specimen with the same initial void ratio. Hence, the changes in the soil structure induced by the addition of polyurethane into the compacted mixture increased the resistance of the soil mass from lateral shrinkage quantified using the free shrinkage ratio. Furthermore, the regression model of the free shrinkage ratio for a wide variety of moisture content was also presented for the compacted polyurethane clay and compacted clay.

BATHYMETRY AND BATHYMETRIC DIFFERENCES MBES MULTIFREQUENCY FOR SEAFLOOR SEDIMENT MAPPING

2023-09-15T15:04:18+00:00

Seafloor sediments have a significant role in the planning and development of coastal areas, especially port areas. Acoustic technology developing today, especially multifrequency Multibeam Echosounder (MBES), is expected to measure seafloor sediment and detect the type and distribution of seafloor sediments. The question posed in this study is how to improve the accuracy of sediment classification using multifrequency MBES. This study uses deep neural networks to classify seafloor sediments in the study area with input bathymetric and bathymetric differences and 74 in situ sediment samples (silt, clayey sand, silty sand, and sandy silt). Sediment classification results show that clayey sand dominates the sediment distribution in the Central and Eastern regions. On the other hand, sandy silt predominates in the western area (harbor pond). Classification of seafloor sediments in the study area has an accuracy of 41.9% (average) and a kappa coefficient of 21.9% (fair). The implication of the study is that bathymetric and bathymetric differences from multifrequency MBES produce a low sediment classification accuracy value of below 50%. Therefore, it needs to be re-evaluated in relation to bathymetric and bathymetric differences and the amount and distribution of sediment sample data needed to improve its accuracy.

POLYMER-MODIFIED CEMENT ASPHALT MORTAR AS INTERLAYER IN THE NON-BALLASTED TRACK OF HIGH-SPEED TRAIN

2023-09-28T09:09:16+00:00

Non-ballasted track consists of a concrete slab bonded firmly to the concrete base by a cement asphalt mortar (CAM) as an interlayer for damping. In practice, interface bonding failure occurs on CAM. Styrene-butadiene rubber (SBR) polymer is proposed as a modifying material to increase the interface bonding strength of CAM. The problem of polymer modification in CAM is probably related to poor compatibility and workability. This study aims to investigate the effect of the SBR polymer pH value on the compatibility and workability in CAM. Compatibility is determined by separation rate. Zeta potential value describes polymer-modified asphalt emulsion (PMAE) activity. Workability is determined by funnel fluidity time and slump flow time. Results showed that increasing the SBR polymer pH value decreased the zeta potential of PMAE. Decreasing zeta potential to be value-neutral results in destabilized asphalt droplets, demulsified, separated water, and asphalt coalescence. Finally, the asphalt coalescence is covered by polymer and forms a binding film on cement. It is affecting the compatibility between PMAE and cement hydration. It results in a low separation rate. Compatibility is achieved by SBR polymer pH 10.0 doses ranging from 1% to 6%. SBR polymer dosage of 1% to 3% led to a deceleration in funnel fluidity time and slump flow time associated with elevated demulsification. Their 4% to 6% dose accelerates funnel fluidity time and slump flow time associated with delaying demulsification. Acceptance of compatibility and workability in CAM is proposed using SBR polymer pH 10.0 dosage of 4% to 6%.

SOIL MECHANICAL CHARACTERISTICS IMPROVEMENT WITH BACTERIAL BIOCEMENTATION TECHNOLOGY

2023-10-02T07:08:19+00:00

The aim of this study is to establish a subgrade layer by field-scale testing using a 6% Bacillus subtilis bacterial solution in Microbially Induced Calcite Precipitation (MICP), altering the bacterial culture's age by four days and curing it for 150 days. Field-scale testing was carried out, starting with soil property tests, followed by tank tests, bacterial growth, and soil mechanical tests using bacterial solutions. The study found that on the field model scale, the unconfined compressive strength increased with the lengthening of the curing period. However, because of the influence of rainfall, high rainfall lowers the soil's carrying capacity. In the 14-day to 45-day test, there is a difference in carrying capacity between layer 1 (0–15 cm) and layer 2 (15–30 cm). Comparing Layers 1 and 2, Layer 1 has a higher (qu) value, but Layer 2 has a higher (qu) value during the 60-150 days test. The optimal value of CBR with MICP stabilization is 20% after 150 days of curing. This increased by four times as compared to soil without bacterial stabilization, while the optimum value of compressive strength increased by three times. The SEM analysis reveals that MICP caused calcite to appear on the soil's surface. The results indicated that bacterial bio cementation stabilization is an alternative method of soil improvement that can enhance the mechanical characteristics of the soil, beneficial for the construction of infrastructure, and is environmentally benign.

CHARACTERISTICS OF ASPHALT CONCRETE WEARING COURSE MIX INCORPORATING RECYCLED TIRE RUBBER AS AN ADDITIVE

2023-10-22T04:02:35+00:00

In Indonesia, flexible pavement is the primary form of road infrastructure. It is typically produced using a binder combined with Buton Granular Asphalt (BGA B 5/20) as an additional binder. Tire rubber waste as an additive is considered an option to reduce environmental pollution and promote sustainable procurement strategies. The objective of this study is to evaluate the results of the Marshall characteristic test for an asphalt concrete wearing course (AC-WC) with tire rubber used as an asphalt binder. Three AC-WC mixtures (0%, 5%, and 10%) were subjected to Marshall characteristic tests. The results of the Marshall stability test showed that the untreated AC-WC mixture had a stability of 1312 kg, while the AC-WC mixture with 5% tire rubber had a stability of 1150 kg, indicating a reduction of 12.3%. Similarly, the 10% tire rubber demonstrated a stability of 1100 kg, reflecting a reduction of 16.2%. The Marshall Quotient for the standard AC-WC mixture was 416.9 kg/mm. In contrast, the 5% tire rubber yielded a Quotient of 354 kg/mm, representing a decrease of 15.1%. Additionally, the 10% tire rubber resulted in a Quotient of 289.4 kg/mm, indicating a reduction of 30.1%. The Marshall characteristics VMA, VIM, VFB, and Flow also met the standard criteria for AC-WC. The addition of tire rubber reduced the bearing capacity and resistance to permanent deformation of the AC-WC. However, it was observed that tire rubber waste can be effectively used as an additional binder for asphalt in AC-WC treatment.

IMPROVING INFILTRATION MODELING FOR PAPUA’S SMALL WATERSHED BY USING RSTUDIO SOFTWARE ANALYSIS

2023-11-05T02:36:57+00:00

Eco-hydrological processes in watersheds are essential for policy development and social growth despite growing environmental concerns. These processes represent a dynamic interaction between the hydrological cycle and ecological elements, with infiltration as one of the important components. According to preliminary studies, the availability of infiltration rate data holds significant importance for irrigation planning, flood management, and water resource studies. Presently, there is a global decrease in hydrological data due to the abundance of water resources in Papua. Existing literature emphasizes the need to evaluate the Kostiakov and Green Ampt models in varied soil textures in Papua, particularly within small watersheds. Therefore, this research compared the performance of the two models on each soil texture using the Hydrological Soil Group classification. It also analyzed modifications for models with unsatisfactory performance through the use of RStudio software analysis with k-fold cross-validation. The results showed that the Green Ampt model performs better than the Kostiakov model for nine soil textures, with average performance values of 0.800 (R), 0.636 (NSE), and 0.588 (RSR). Although the Kostiakov model initially underperformed, it was enhanced to the Pristianto Model by integrating soil properties such as water content (w), porosity (n) and sand content (Sn). Further evaluation in other small watersheds is needed to confirm its robustness. In conclusion, this research filled hydrology data gaps in Papua, which resulted in an infiltration model tailored to the soil characteristics of small watersheds.

DOUBLE-ROW PILE REINFORCING ON A CRITICAL SLOPE AT NATIONAL ROAD IN TABANAN, BALI

2023-11-19T13:28:03+00:00

Due to heavy rain, a landslide occurred on the high slope at the National Road in Tabanan, Bali, and is forecasted to reoccur. Thus, the double-row piles will be analyzed as an alternative method to improve allowable bearing capacity (q_a) and slope stability to mitigate this area. This study used various 2D and 3D numerical modeling techniques to analyze the slope model under two variables: the installment of parallel and nonparallel (zigzag) pile configurations and variations in a second-row pile diameter. With the smallest diameter (D = 0.3 m), the first row of piles has a diameter of 0.6 m and a pile spacing of (s) = 4D. The reinforcing piles were installed into the actual slope model. In addition, the second-row pile diameter varies from 0.3 to 0.6 m. Considering the standardized traffic load, PLAXIS and ABAQUS were implemented to numerically analyze the factor of safety (FS) and q_a of the 2D and 3D finite element method (FEM). Compared with the unreinforced reinforcement of two rows of piles arranged in parallel, the FS increased significantly by 33.06% in the 2D FEM and 32.82% in the 3D FEM. Yet, the model with a zigzag configuration enhanced the FS by 33.20% in the 3D FEM. However, the numerical models showed a slight improvement in the q_a in both 2D and 3D FEM. The slope model defined the highest FS and q_a with pile diameter, D2 = 0.6 m (P2D1). Additionally, a rotational type of failure occurred on the slope toe.

NATURAL AGGREGATE SUBSTITUTION BY STEEL SLAG WASTE FOR CONCRETE MANUFACTURING

2023-09-02T17:33:46+00:00

The release of steel slag into the environment has substantial repercussions, simultaneously affecting both the ecosystem and the economy. Therefore, the management and recovery of this waste demand careful consideration. In the context of the circular economy, this study aims to explore the feasibility of utilizing steel slag waste as a substitute aggregate for natural coarse and fine aggregates in the production of high-quality concrete. Throughout this research, concrete mixtures were developed by varying natural aggregate substitution rates with steel slag waste at 0, 25, 50, 75, and 100%. Comprehensive tests, encompassing physical, mineralogical, chemical, and mechanical analyses, were conducted on the steel slag waste to ascertain its primary technical properties. In all mixtures incorporating steel slag waste, compressive strength tests consistently revealed values surpassing those of the reference concrete. Notably, there were improvements of approximately 12% for coarse aggregate substitution and 32% for sand substitution. Assessments of flexural strength at 7 and 28 days underscored the substantial positive influence of fine and coarse aggregate substitution, especially at a 50% fine aggregate replacement, contributing significantly to enhanced flexural strength compared to conventional concrete. Furthermore, laboratory examinations indicated that the 28-day compressive and flexural strength, as well as water absorption of concrete, increased with slag content, albeit at the expense of reduced workability. Ultimately, the findings demonstrate the effective utilization of slag as a replacement for natural aggregates, maintaining the compressive and flexural strength of the concrete.

THE PHYSICAL AND MECHANICAL PROPERTIES OF SINGLE PUMICE SAND PARTICLE

2024-03-23T06:53:18+00:00

Pumice sand is a volcanic material widely distributed in volcanic areas such as Japan, Indonesia, and countries traversed by volcanic mountains. Geotechnical problems regarding pumice sand often occur in these areas, such as landslides because of the pumice crushable structure. Based on previous research, some failure phenomena are caused by the existing pumice layer, and not so many studies describe the behavior of pumice single particle located at Kyushu Island, Japan. This study conducted a series of tests to clarify pumice material's microscopic and mechanical properties. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) tests were carried out on pumice materials to determine the microscopic and chemical compounds in the pumice material. Then, single-particle crushability tests were carried out as representative of the mechanical behavior of pumice sand particles. The approach using linear regression fitting is carried out using conventional frequentist and Bayesian hierarchical approaches to obtain the strength behavior of the pumice sand. An overview of pumice microscopy conditions and minerals can be helpful when ground improvement and soil stabilization are discussed for this pumice material and the effect of particle shape on pumice strength is observed. According to this study, oxygen, silica, and alumina dominate pumice sand chemical components. The aspect ratio and the roundness coefficient of pumice sand do not significantly impact particle stress. Particle size reduces and increases particle stress in single-particle crushability tests. Single-particle crushability reduces pumice particle pore area and increases the number of pores.

INVESTIGATION OF STRESS BEHAVIOR IN EMBANKMENT DUE TO RAINFALL INFILTRATION

2024-03-23T07:29:54+00:00

In recent years, sudden heavy rains due to climate change have increased, and there are many cases of collapse of soil structures. In particular, embankment structures are social infrastructure structures that are essential to our lives, so the damage caused by their collapse is enormous, and it is necessary to prevent this from happening. However, the factors and mechanisms leading to the collapse of embankment structures have not been sufficiently analyzed and elucidated, and elucidation is urgently needed. Therefore, in this study, we conducted an embankment model experiment focusing on rainfall and a reproduction analysis using the air-dissolved unsaturated soil/water/air-coupled finite analysis code in an attempt to understand the moisture state and stress behavior of the embankment due to rainfall. As a result, through model experiments, we were able to confirm that rainfall penetrates from the embankment crest and the slope, causing the embankment to collapse from near the toe of the slope, and it was clarified that this is the mechanism by which the embankment collapses due to rainfall. In addition, the reproduction analysis confirmed qualitative agreement with the model experiment and clarified the usefulness of this analysis code. Furthermore, the stress behavior of the embankment, which is difficult to clarify through experiments, was clarified. In this way, the internal conditions and collapse mechanisms of embankments due to rainfall were elucidated using two methods: experiment and analysis.

EVALUATION OF INFINITE SLOPE STABILITY WITH VARIOUS SOILS UNDER WET-DRY CYCLE

2024-03-23T08:03:41+00:00

Rainwater infiltration is one of the main triggering factors in slope failure. Therefore, exploring the unsaturated slope behavior is essential. However, studies generally ignored the impact of soil-water characteristic curve (SWCC) hysteresis caused by wet-dry cycles in engineering practice. SWCC measured in the drying process is commonly used to estimate slope behavior in the wet-dry cycle. Three soils of Toyoura sand, Hiroshima decomposed granite soil (Masado soil), and DL clay will be taken as examples to examine the infinite slope stability under the effect of SWCC hysteresis. Firstly, this research examines soils' SWCC and suction stress characteristic curves (SSCC). Then, the factor of safety (FOS) changes are further analyzed when suction stress is considered the confining pressure. The results indicate that FOS for soils with small cohesion and air-entry value is greatly affected by SWCC hysteresis. As the depth between the selected slip surface and slope surface increases, the disparity between FOSs calculated through wetting FOS and drying FOS will decrease sharply. Therefore, for shallow slope stability analysis, only using the SWCC measured during the drying process to evaluate the entire wet-dry cycle might lead to underestimating slope failure potentiality.

INVESTIGATION OF THE COLLAPSE OF THE CINCIN LAMA BRIDGE WITH CONSIDERATION OF FATIGUE DAMAGE

2024-03-23T07:43:43+00:00

The Cincin Lama bridge is a crucial component of a major road in Java Island, Indonesia. It comprises six spans of the Callender Hamilton-type truss bridge, with each span measuring 50 meters. Tragically, one of its six spans collapsed during operation on April 17th, 2018. To understand the cause behind this incident and extract valuable lessons from it, an investigation utilizing finite element analysis was initiated. The primary objective of this investigation was to pinpoint the root cause that precipitated the collapse of the bridge. To achieve this critical goal, the investigation commenced with a thorough examination of the site investigation reports, coupled with an assessment of the bridge's adherence to the Indonesian design code applicable during its construction. Subsequently, the bridge underwent analysis based on the most recent Indonesian codes, taking into account the estimated ultimate load experienced at the time of the accident. To consider the possibility of pre-existing defects that may have contributed to the collapse, a fatigue analysis was also conducted. To ensure a precise estimation of the traffic load, weight in motion (WIM) data was utilized in the fatigue analysis. Through this detailed examination, it was revealed that the collapse was most likely triggered by a combination of an overloaded truckload and accumulated fatigue damage prior to the accident. The knowledge gained from this investigation will undoubtedly contribute to the improvement of safety measures and engineering practices in the construction of bridges, ensuring a more secure infrastructure for Indonesia's transportation network.

EFFECT OF SHREDDED RUBBER TIRE AS PARTIAL REPLACEMENT FOR COARSE AGGREGATES IN FLY ASH-BASED PERVIOUS CONCRETE

2024-03-23T08:20:43+00:00

The need to improve traditional concrete practices and the existing waste problem in the Philippines has opened an opportunity for by-products, such as scrap rubber tires and fly ash, as sustainable alternative materials in pervious concrete. This study investigates the effect of shredded rubber tires and fly ash content on the strength and permeability of pervious concrete. A total of 15 mix designs, with varying replacement ratios based on weight, were produced and tested for compressive strength, split tensile strength, and infiltration rate. In particular, the percentage replacements tested in the study were 0%, 10%, 20%, 30%, and 40% for the shredded rubber tires, while fly ash ratios were set at 0%, 10%, and 20%. Two-way ANOVA test and desirability function statistical analyses were conducted to determine the optimal replacement of shredded rubber tires and fly ash. Results showed that the addition of shredded rubber tires produced a decreasing trend, while increasing the fly ash content exhibited an increasing trend, both on the compressive strength and split tensile strengths. On the other hand, the infiltration rate increased with the addition of rubber aggregates. The research findings also indicated that using up to 10% shredded rubber tires, with 10-20% fly ash, yields a more desirable pervious concrete than the conventional mix.

EFFECT OF EPOXY RESIN AND CEMENT AS GROUT ON THE MECHANICAL PROPERTIES OF SILT

2023-10-16T05:02:25+00:00

Grouting is a method or technique that is carried out to improve underground conditions by injecting material that is still in a liquid state, through pressure (it can inject semi-viscous materials) so that the material will fill in all the existing cracks and holes. The main purpose of grouting in this study is to strengthen the soil and increase soil strength. The injection material will enter the soil pores, react with the soil, and harden to form a strong and sturdy bond. The grouting material in this study was applied to filling boreholes in pile foundations when a load is applied, will be held by the frictional resistance between the piles, cement, epoxy paste, and soil. The filling materials for this grouting are soil paste, cement, and epoxy resin which were observed in a laboratory with a tensile test system to see the behavior of increasing soil strength at 7 days, 14 days, and 28 days. Based on the results of laboratory tests carried out, the use of epoxy resin, cement, soil, and water as grouting materials for foundations increases the soil stiffness value expressed in the modulus of elasticity value and increases the soil shear parameter values, namely the values c and φ. The increase in value occurs at the ratio ER/W = 80/180 where with a longer curing time, namely 28 days, the value of shear stress, c and φ and the modulus of elasticity are each 2.3kg/cm²; 39,520; 12.08 MPa.

DETERMINATION OF OPTIMUM CEMENT CONTENT FOR SILTY SAND SOIL STABILIZATION AS THE BASE COURSE

2023-11-09T02:31:00+00:00

The aggregate base course is important in the flexible pavement structure, requiring quality materials. In areas where quality material is difficult to find, local soil stabilization using cement is needed to obtain material to replace the aggregate base course. This study aimed to determine the optimum cement content in stabilizing sand-silty soil that meets the requirements specified in the General Specification of Highways 2018 for Road and Bridge Works and to find the effect of pH-soaking water. The research was conducted in the laboratory by testing the Unconfined Compressive Strength of soil cement using variations in cement content of 3%, 5%, 8%, and 10% of the dry weight of soil, soaking time of 3, 7, 14, and 28 days; and pH of soaking water (tap water with a pH value of 8, water with pH value of 4 (containing H₂SO₄), water with pH value of 9 (containing NaOH)). Cement content of 8% and 10% meets the minimum UCS value according to road specifications. The optimum cement content (which produces the UCS target specification value of 2353.60 kPa) is 9% on the seventh day. Soaking water with pH 4 and 9 decreased the UCS of soaking water with a pH value of 8. A soil cement base course can substitute an aggregate base course in areas with inadequate aggregate material with an 80% CBR value.

USER BEHAVIOR IN A STATION AREA SPACE OF A LOCAL CITY CENTER –A CASE STUDY OF THE OZAKI STATION IN HANNAN CITY

2024-03-24T04:50:16+00:00

Local governments develop appropriate location plans to promote forming station-front spaces in compact cities to create lively city centers. However, plans clarifying the trends and movements of station users are limited. Understanding user behaviors and trends is necessary to meet local needs. Three surveys were conducted around the Ozaki Station in Hannan City, Osaka Prefecture, as a case study. The case study investigated station users' staying behavior based on video camera recordings, circulation using a behavior tracking survey, and parking space usage using an observational field survey. The results showed that people who stayed in front of the Ozaki Station used areas conducive to staying and with little interference from passersby. They spent an average of approximately 4 min in the station area. On the north side, 94.6% of the people used the front space of the station on their way home. On the south side, 36.5% entered a store or facility for purchasing. Parking space occupied 77.3% of the underused land around the station, and 41.5% of the parking space had a parking ratio of 30% or less. In conclusion, this study found that the area around the Ozaki Station could become a commercial, recreational, or leisure center rather than a mere transit point. Therefore, utilizing underused parking spaces and creating public lingering areas have become primary concerns.