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Agata Iwan Candra
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U Karst
Published by Universitas Kadiri
ISSN : 25794620     EISSN : 25810855     DOI : http://dx.doi.org/10.30737/ukarst
Core Subject : Engineering,
Civil Engineering, Building, Construction & Architecture
U KaRsT is a journal of the civil engineering research the University of Kadiri published twice a year in April and November. First published in April 2017. U KaRsT already has both ISSN printed and online, for ISSN (Print) is 2579-4620, and ISSN (Online) is 2581-0855.
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Articles 6 Documents
 1 
Search results for , issue "Vol. 9 No. 1 (2025): APRIL" : 6 Documents clear
Consistency of Compressive Strength in Concrete with 10% Rice Husk Ash Substitution Alfaridh Pasya, Salman; Bima Mahardana, Zendy; Mustofa, Imam; Iwan Candra, Agata
UKaRsT Vol. 9 No. 1 (2025): APRIL
Publisher : Kadiri University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30737/ukarst.v9i1.6583

Abstract

Using rice husk ash (RHA) in concrete technology represents a significant innovation in promoting sustainability. The pozzolanic properties of RHA enhance concrete quality through microstructural refinement while mitigating environmental impacts. However, replacing 10% of cement with RHA has inconsistent effects on compressive strength. Such variability may limit the broader application of RHA in structural concrete due to uncertainties in performance prediction, quality assurance, and design safety. While some studies report strength improvements, others note reductions often attributed to limited samples size, material inconsistencies, and variations in mixing or curing processes. This study aims to statistically validate the consistency of compressive strength in concrete with 10% RHA substitution by increasing the sample size and controlling key variables. Nine specimens per test condition were evaluated using a water-cement ratio of 0.53, submersion curing and ASTM C39 testing standards. Compressive strength assessment was conducted at 7 days. The result show a 7.54% increase in compressive strength, from 22.71 MPa to 24.42 MPa, with a coefficient of variation (CV) of 2.26%, well below the 10% threshold. In contrast, earlier studies with smaller sample sizes reported CVs as high as 42.65%, indicating greater statistical variability. This improvement is attributed to the increased sample size, material quality control, and uniform mixing, which ensured homogeneous RHA distribution and optimized pozzolanic reactions. By applying a controlled-variable approach and increasing the sample size, this study addresses prior inconsistencies and reinforces the validity of RHA as a viable cement substitute in concrete.
Landslide Mechanisms in the Cisumdawu Toll Road through a Geoforensics Approach to Increase Slope Stability Mardjuni, Adhystira; Pramono Rahardjo, Paulus; Aldiamar, Fahmi
UKaRsT Vol. 9 No. 1 (2025): APRIL
Publisher : Kadiri University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30737/ukarst.v8i1.6587

Abstract

Landslides are a significant threat to infrastructure in tropical regions like Indonesia, especially in projects that cross volcanic slopes. A significant case occurred on the Cisumdawu Toll Road Section 2, triggered by high rainfall and water-saturated young volcanic soil. Given the complexity of such failures, comprehensive investigations are crucial. This study aims to analyze the causes and mechanisms of landslides in the Ciherang Village, specifically at STA 19 KM 65 using a geoforensics approach. This approach involves field investigations to collect geotechnical and geophysical data such as boring logs, SPT, pressure meters, inclinometers, and geoelectric resistivity testing. These were used to reconstruct subsurface conditions before failure. Numerical modeling was then performed with variations in groundwater level (GWL) and K₀ to simulate slope stability and identify failure triggers. The results show that landslides was translational, occurring in the transition zone between sandy silt (tuff) and weathered tuff breccia layers at depths of 30–35 meters, where differences in permeability made the zone vulnerable. The decrease in GWL significantly improved slope stability, increasing the safety factor to 1.435, while K₀ variation had a lesser impact. A combination of bored piles, ground anchors, soil nailing, and slope regrading effectively stabilized the slopes. These findings contribute to a better understanding of the mechanisms and causes of landslides so that mitigation strategies can be more targeted to increase slope stability.
Evaluation of Seawater Intrusion and Impact on Infrastructure in the Coastal Area of ​​North Surabaya Soebagio; Kathulistiani, Utari; Pahing, Johan; Datom, Konstantinus
UKaRsT Vol. 9 No. 1 (2025): APRIL
Publisher : Kadiri University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30737/ukarst.v9i1.6590

Abstract

Several wells of coastal residents at North Surabaya experienced changes in odor, taste, and color indicating seawater intrusion. This phenomenon can cause an increase in groundwater salinity, which impacts clean water quality, public health, and infrastructure resilience. Therefore, it is important to evaluate seawater intrusion in the area. This study aims to evaluate the level of seawater intrusion, determine the distribution pattern of intrusion, and identify high-risk zones for seawater intrusion and the level of infrastructure vulnerability to corrosion. The methods used include analysis of physical and chemical parameters of groundwater, intrusion assessment using the Revelle Index and Electrical Conductivity (EC), and mapping based on Geographic Information System (GIS) to determine the distribution pattern of intrusion. The laboratory's well water sample testing showed an average EC score approaching 1500 μS/cm, and the R-value was far above 1. It meant that well water in North Surabaya has been facing seawater intrusion from medium to high levels. It also predicted the distance of seawater intrusion is about 2,5 km from the coastline and has the most significant risk of infrastructure degradation due to corrosion. Seawater intrusion in Surabaya is caused by geographical proximity to the sea, aquifers' hydrodynamic factors, and high groundwater exploitation. The results of this study contribute to providing a seawater intrusion risk map that can be a reference for the government and policymakers in developing mitigation strategies and groundwater management policies to reduce the impact of seawater intrusion.
Statistical Validation of 2% Lignosulfonate as a Sustainable Stabilizer for Expansive Clay Rivianto, Arif; Candra, Agata Iwan; Nursandah, Fauzie; Mustofa, Imam
UKaRsT Vol. 9 No. 1 (2025): APRIL
Publisher : Kadiri University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30737/ukarst.v9i1.6594

Abstract

Expansive clay soils undergo volumetric changes due to fluctuations in moisture content, which can cause structural damage to foundations, pavements, and embankments. Traditional stabilization methods, such as cement and lime, are effective but have a significant environmental impact, highlighting the need for more environmentally friendly alternatives. Lignosulfonate (LS), an organic stabilizer derived from industrial by-products, offers a more sustainable approach to improving soil strength and stability. This study evaluates the effect of 2% lignosulfonate on the unconfined compressive strength (UCS) of expansive clays. The research method involved mixing LS at 2% of the dry weight of the soil into the expansive clay (CL-ML) and conducting UCS tests on three untreated (control) samples and six treated samples. Statistical analysis was used to assess the significance of the differences between the two groups. Results show that the UCS increased from 236.29 kPa in the control group to 291.49 kPa in the treated group, reflecting a 23.37% improvement. Poisson's ratio decreased from 0.300 to 0.200, indicating reduced lateral deformation and enhanced soil stiffness, which improves the bearing capacity and stability of structures built on it. The UCS values ​​were observed to be consistent supported by low standard deviation. The study highlights the critical role of adequate sample replication and control over operational variables such as moisture content, compaction, and LS dispersion to ensure reliable and reproducible stabilization outcomes. This study strengthens the empirical basis for the application of LS as a sustainable and environmentally friendly stabilizer for expansive clays.
Optimization System Irrigation Using Linear Programs in the D.I. Delta Brantas Region Sidoarjo (Case Study: Dungus Intake) Nisa, Khoirotun; Azmi Dewi Nusantara, Danayanti
UKaRsT Vol. 9 No. 1 (2025): APRIL
Publisher : Kadiri University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30737/ukarst.v9i1.6628

Abstract

Global food security is facing challenges due to climate change and increasing water needs for agriculture. One area experiencing these problems is the Dungus intake irrigation area in Sidoarjo Regency, which faces water management due to land use changes and uncertainty of water availability. As a result, the efficiency of water distribution decreases, and agricultural productivity is disrupted, so efforts are needed to optimize the irrigation system. This study aims to optimize the irrigation system in the Dungus Intake Irrigation Area to increase the efficiency of water distribution. This effort is carried out by determining the optimal planting pattern and irrigation water allocation using the linear programming method. This method is applied by considering the mainstay discharge of the Dungus intake, crop irrigation needs, and economic benefits from various cropping pattern scenarios. The results show that the mainstay discharge ranges from 0,479–0,754 m³/sec with an allocation discharge of 2.604 m³/sec. The optimal alternative cropping pattern 3, with a land area of ​​1.890 ha, consisting of rice, corn, and shallots in three planting seasons, produces a maximum profit of Rp 242.087.200.000 per year. This study can develop an irrigation optimization model based on hydrology and economics that can improve the efficiency of water distribution. This irrigation optimization model provides a reference for irrigation managers and farmers in designing better water distribution strategies that can increase agricultural yields and economic profits through more appropriate water allocation and optimal land use.
Satisfaction and Determinants of the Decision to Switch from Private Vehicles to Commuter Trains in Merak–Rangkasbitung Mahendra, Muhammad Oka; Djuneydi, Muhammad
UKaRsT Vol. 9 No. 1 (2025): APRIL
Publisher : Kadiri University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30737/ukarst.v9i1.6629

Abstract

Urban population growth has had an impact on traffic congestion. Although public infrastructure is available, public preference for private vehicles remains high. This occurs on the Merak-Rangkasbitung route which is served by the train. The gap between service availability and user preferences indicates the need to study mode selection behavior and the factors that influence it. This study aims to analyze motorcycle and car users' tendency to shift their transportation modes from private vehicles to the train service on the Merak- rangkasbitung route. A quantitative approach was carried out using a questionnaire survey method on 300 respondents using a dual-stratum sampling technique. The analysis used the Importance Performance Analysis (IPA), Customer Satisfaction Index (CSI), and Chi-Square test. The IPA results showed a service suitability value of 86.57%, while CSI showed a satisfaction level of 72.86% (satisfied category). The Chi-Square test results identified that the factors influencing the transportation mode choice differed between segments. For motorcycle users, it was influenced by age, car ownership, and reason for travel, while car users were influenced by occupation, travel costs, reasons and purposes of travel. These findings emphasize the importance of a policy approach based on user segmentation and strengthening integration between modes to improve the effectiveness of train services. With an adaptive service strategy and targeted incentive policies, the transformation towards sustainable urban mobility can be realized.

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