Garuda - Garba Rujukan Digital

PENINGKATAN KUAT TEKAN PADA BETON GEOPOLIMER AKIBAT METODE PERAWATAN DIPANASKAN Wibowo, Kevin Aprilio; Christianto, Daniel; Widjajakusuma, Jack
JMTS: Jurnal Mitra Teknik Sipil Volume 7, Nomor 1, Februari 2024
Publisher : Prodi Sarjana Teknik Sipil, FT, Universitas Tarumanagara

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24912/jmts.v7i1.25150

Studies about pozzolan material to reduce cement usage have been conducted for many times. Concrete made of pozzolan material was known as geopolymer concrete. Geopolymer concrete’s weaknesses were low duration of setting time and the low level of workability. The precast method was used to overcome these weaknesses. Concrete with a high initial compressive strength enable a more efficient implementation of the precast method due to it able to be released from the formwork without getting damaged. This study aims to see the increase in compressive strength due to the method of dry curing. In addition to that, differing from the geopolymer concrete without palm oil fuel ash, this study added 5% of palm oil fuel ash to see the effect of it on compressive strength. Constructed specimens were then cured at room temperature or heated in an oven with a temperature of 60°C for 24 hours. The ratio of alkaline activator to fly ash that were used in this research are 0,55:1 and 0,825:1. The specimen which was only a day old with 0,55:1 ratio experienced 2 times increase in compressive strength when being heated compared to the specimen cured at room temperature. The specimen which was of the same age with 0,825:1 ratio also experienced 3,5 times increase in compressive strength after being heated compared to those at room temperature. The increase of compressive strength was due to the heating process enabling the chemical reaction to occur faster. Abstrak Penelitian untuk memanfaatkan material pozzolan untuk mengurangi penggunaan semen sudah banyak dilakukan. Beton yang menggunakan material pozzolan disebut beton geopolimer. Kelemahan dari beton geopolimer adalah durasi setting time dan tingkat kelecakan yang rendah. Oleh karena itu, metode pracetak dapat digunakan untuk mengatasi kelemahan tersebut. Beton dengan kuat tekan awal yang tinggi dapat membuat metode pracetak semakin efisien karena beton dapat dilepaskan dari bekisting dan tidak rusak. Penelitian ini bertujuan untuk melihat peningkatan kuat tekan akibat metode perawatan benda uji dengan cara dipanaskan. Selain itu, pada penelitian ini ditambahkan abu cangkang kelapa sawit sebanyak 5% untuk dilihat pengaruhnya terhadap kuat tekan dibanding beton geopolimer tanpa abu cangkang kelapa sawit. Benda uji yang sudah dibuat, dirawat pada suhu ruangan atau dipanaskan pada oven dengan suhu 60°C selama 24 jam. Rasio alkali aktivator terhadap abu terbang yang digunakan pada penelitian ini adalah 0,55:1 dan 0,825:1. Hasil peningkatan kuat tekan yang didapat pada saat benda uji berumur 1 hari adalah benda uji dengan rasio 0,55:1 yang dipanaskan mengalami peningkatan kuat tekan sekitar 2 kali dan pada rasio 0,825:1 mengalami peningkatan kuat tekan sekitar 3,5 kali dibanding benda uji yang dirawat pada suhu ruangan. Hal itu disebabkan oleh pemanasan benda uji membuat reaksi kimia terjadi lebih cepat dan kuat tekan meningkat.

The Role of Geopolymer Concrete in Achieving Sustainable Development Goals Wibowo, Kevin Aprilio; Widjajakusuma, Jack
FaST - Jurnal Sains dan Teknologi (Journal of Science and Technology) Vol. 9 No. 1 (2025): NOVEMBER
Publisher : Universitas Pelita Harapan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19166/jstfast.v9i2.10386

A sense of safety and comfort is a fundamental right for all people. The United Nations strives to fulfil this through the establishment of 17 Sustainable Development Goals (SDGs). The construction sector plays a significant role in achieving these goals, particularly in the areas of Good Health and Well-being, Clean Water and Sanitation, Decent Work and Economic Growth, Sustainable Cities and Communities, Responsible Consumption and Production, and Climate Action. One key effort in the construction sector is replacing Portland cement with pozzolanic materials. Cement production emits large amounts of carbon dioxide, contributing substantially to global warming. To address this, pozzolanic materials such as fly ash are used as a substitute for cement in the production of geopolymer concrete. Based on compressive strength tests on cylindrical specimens and flexural strength tests on beam specimens, geopolymer concrete demonstrates high potential for structural applications. Its mechanical performance is comparable to that of conventional concrete, making it a promising alternative that supports sustainable development in the construction industry.

High-Reliability Teams at Sea: The Role of Psychological Safety, Human–System Interaction, and Workload in Error Reporting Behavior among Offshore Workers Gomargana, Chrysan; Wibowo, Kevin Aprilio; Widjajakusuma, Jack
FaST - Jurnal Sains dan Teknologi (Journal of Science and Technology) Vol. 9 No. 1 (2025): NOVEMBER
Publisher : Universitas Pelita Harapan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19166/jstfast.v9i2.10416

Offshore oil and gas operations demand high reliability under extreme physical and psychological conditions. Despite robust engineering systems, many accidents still stem from human and organizational factors. This study examines the role of psychological safety, human–system interaction, and workload in predicting error reporting behavior among offshore workers. A quantitative, cross-sectional design was applied using validated self-report scales: the Psychological Safety Scale (Edmondson), System Usability Scale (SUS), NASA Task Load Index (NASA-TLX), and an adapted Error Reporting Behavior Scale. Data were collected from 188 offshore workers in Indonesia through online questionnaires. Multiple linear regression analysis revealed that psychological safety (β = .38, p < .001) and human–system interaction (β = .27, p < .001) significantly and positively predicted error reporting behavior, while workload showed a significant negative effect (β = −.23, p < .001). The model accounted for 36% of the variance in error reporting (R² = .36). These findings indicate that workers are more likely to report errors when they feel safe to speak up, perceive systems as user-friendly, and experience manageable workloads. The study highlights the need for integrated interventions that simultaneously foster psychological safety, ergonomic system design, and balanced workload management to enhance proactive safety behavior in offshore environments. This research contributes to the intersection of industrial–organizational psychology and human factors engineering, emphasizing that safety performance in high-reliability organizations relies on both social and technological resilience. These findings align with Sustainable Development Goal 9 (Industry, Innovation and Infrastructure), reinforcing that resilient and sustainable industrial systems require the integration of human factors into safety management and system design.

Performance of Soil Biogrouting as a Subgrade Material of the Road Pavement Widjajakusuma, Jack; Waruwu, Aaazokhi; Kusnadi, Yulia Yunita; Lujaya, Jason; Wibowo, Kevin Aprilio
Civil Engineering Journal Vol. 11 No. 10 (2025): October
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2025-011-10-017

Soft clay subgrade is unsuitable for road pavement because it has low bearing capacity and CBR value. Therefore, the soil needs stabilization, but with a sustainable stabilization method. One of these methods is biogrouting, namely grouting, which uses bacteria. Thus, the main objective of this study was to determine the performance of Bacillus subtilis and Bacillus amyloliquefaciens bacteria in stabilizing the soil. The performance of these bacteria was quantified by the CBR value and soil-bearing capacity experimentally in a laboratory model test with each soil thickness of 0-30 cm. The CBR value of the soil improved by the biogrouting method by about 4 times the CBR value of untreated soil. The increase in bearing capacity was obtained about 4 times for treated soil with Bacillus subtilis and about 5 times for treated soil with Bacillus amyloliquefaciens. The layer thickness significantly improves the performance of the subgrade at a layer thickness of 20 cm. The new result of this study is that both bacteria are native Indonesian bacteria, so they are suitable for use in Indonesia. In addition, Bacillus amyloliquefaciens has never been used in research to increase soil-bearing capacity.

Predicting the Maximum Dynamic Deflection of Rigid Pavement Slab at Toll Road Due to Vehicle Load Haripriambodo, Tjatur; Alisjahbana, Sofia W.; Najid, Najid; Widjajakusuma, Jack
Jurnal Locus Penelitian dan Pengabdian Vol. 4 No. 12 (2025): JURNAL LOCUS: Penelitian dan Pengabdian
Publisher : Riviera Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.58344/locus.v4i12.5169

Several points on Indonesia Toll Road found cracks in the concrete slab very early, not long after the road was operated, especially on toll roads with large volumes of vehicles (trucks) transporting materials and industrial products. The most common failure modes that occur in rigid pavements are fatigue cracks in the concrete slab and/or erosion of the material in the subbase. Both are related to excessive stress and deflections in the concrete slab. Currently, vehicular loading is commonly modelled as static load in concrete design guidelines although it has a dynamic nature. However, dynamic analysis of concrete pavements has been attracting researcher’s attention. The American Association of State Highway and Transportation Officials (AASHTO) conducted an experimental test of concrete pavements to determine effect of vehicle velocity from 3.2 km/h to 95.6 km/h by using different single truck vehicles. The AASHTO result showed that increased vehicle speed from 3.2 km/h to 95.6 km/h decreased pavement responses by about 29%. This research was intended to predict dynamic deflection through implementation Pasternak – Vlasof foundation model and primary data. Deflection was successfully calculated through numerical analysis by taking finite element method. Result was obtained maximum deflection that happened at 2 km/hour vehicle speed. Attention was also paid to 40 km/hour vehicle speed which produces relatively higher deflection than others.

Comparative Analysis of Columns Ratio on Structural Performance and Cost Efficiency Wibowo, Kevin Aprilio; Widjajakusuma, Jack
Jurnal Teknik Vol 23 No 2 (2025): Jurnal Teknik
Publisher : Universitas Negeri Gorontalo

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.37031/jt.v23i2.686

Planning is crucial in construction as it can significantly reduce costs by aligning structural design with requirements while minimizing excess. This study evaluates the structural performance of columns with different shapes and dimensions, utilizing data from the construction site and Indonesian National Standards (SNI). The analysis reveals that square-shaped columns, with a cross-section ratio close to 1, require less material than rectangular columns, with a 17.35% lower concrete volume and a 23.37% smaller formwork area. However, the reinforcement needed for square columns is 6.38% higher. Overall, square columns lead to a 15.42% reduction in production costs. This also results in lower cement consumption, contributing to decreased CO₂ emissions—Design B using 856.32 kg (18.52%) less cement than Design A. The results support the principles of the Sustainable Development Goals (SDGs), particularly SDG 9 (Industry, Innovation, and Infrastructure), SDG 11 (Sustainable Cities and Communities), SDG 12 (Responsible Consumption and Production), and SDG 13 (Climate Action). These findings align with the Sustainable Development Goals (SDGs), emphasizing the importance of sustainability alongside cost efficiency in structural planning.

Behaviour of Synthetic Polymer-Modified Warm Mix Asphalt Under Oven Ageing Simulation Christian G. Daniel; Jack Widjajakusuma; Erik S. Setiawan
Journal of Civil Engineering Vol. 38 No. 3 (2023)
Publisher : Institut Teknologi Sepuluh Nopember (ITS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20861206.v38i03.7455

This research evaluates the mechanical properties and fracture behaviour of ethylene-vinyl acetate (EVA) polymer-modified warm mix asphalt under the influence of ageing simulated through oven heating at 85oC in two different durations of 2 and 8 days. EVA contents of 4 - 6% of binder weight were employed, and the effect was measured through the semi-circular bending (SCB) test. Volumetric properties measurement showed negligible effect of polymer addition, with the difference in air void ratio ranging from 0.5% to 8% compared to the control mix. Meanwhile, the density and void in mineral aggregate (VMA) differed by a maximum of 2% compared with the control mixture. Moreover, the increase in the heating period was found to enhance the tensile strength, with a maximum difference of 81.72% exhibited by the mix with 0.5% EVA, corresponding to its tensile strength from the 8-day ageing conditioning by 28% larger than the control mix. Moreover, crack resistance and flexibility indexes (CRI and FI) were inversely proportional to the increase of polymer dosages for both 2- and 8-day aged specimens from being 20.5% and 52% to 6.4% and 18.3% larger than the control mixture, respectively, with the 8-day aged specimens having the CRI of 8% larger and FI of 8.7% smaller than the 2-day aged samples, indicating a brittle behaviour in respect to the ageing duration. Conclusively, the heating ageing simulation results in a brittle asphaltic mixture modified with EVA, displayed with higher strength and lower flexibility, particularly at 5% to 6% w/t.

The Role of Geopolymer Concrete in Achieving Sustainable Development Goals Wibowo, Kevin Aprilio; Widjajakusuma, Jack
FaST : Jurnal Sains dan Teknologi Vol. 9 No. 2 (2025): NOVEMBER
Publisher : Universitas Pelita Harapan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19166/jstfast.v9i2.10386

A sense of safety and comfort is a fundamental right for all people. The United Nations strives to fulfil this through the establishment of 17 Sustainable Development Goals (SDGs). The construction sector plays a significant role in achieving these goals, particularly in the areas of Good Health and Well-being, Clean Water and Sanitation, Decent Work and Economic Growth, Sustainable Cities and Communities, Responsible Consumption and Production, and Climate Action. One key effort in the construction sector is replacing Portland cement with pozzolanic materials. Cement production emits large amounts of carbon dioxide, contributing substantially to global warming. To address this, pozzolanic materials such as fly ash are used as a substitute for cement in the production of geopolymer concrete. Based on compressive strength tests on cylindrical specimens and flexural strength tests on beam specimens, geopolymer concrete demonstrates high potential for structural applications. Its mechanical performance is comparable to that of conventional concrete, making it a promising alternative that supports sustainable development in the construction industry.

High-Reliability Teams at Sea: The Role of Psychological Safety, Human–System Interaction, and Workload in Error Reporting Behavior among Offshore Workers Gomargana, Chrysan; Wibowo, Kevin Aprilio; Widjajakusuma, Jack
FaST : Jurnal Sains dan Teknologi Vol. 9 No. 2 (2025): NOVEMBER
Publisher : Universitas Pelita Harapan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19166/jstfast.v9i2.10416

Offshore oil and gas operations demand high reliability under extreme physical and psychological conditions. Despite robust engineering systems, many accidents still stem from human and organizational factors. This study examines the role of psychological safety, human–system interaction, and workload in predicting error reporting behavior among offshore workers. A quantitative, cross-sectional design was applied using validated self-report scales: the Psychological Safety Scale (Edmondson), System Usability Scale (SUS), NASA Task Load Index (NASA-TLX), and an adapted Error Reporting Behavior Scale. Data were collected from 188 offshore workers in Indonesia through online questionnaires. Multiple linear regression analysis revealed that psychological safety (β = .38, p < .001) and human–system interaction (β = .27, p < .001) significantly and positively predicted error reporting behavior, while workload showed a significant negative effect (β = −.23, p < .001). The model accounted for 36% of the variance in error reporting (R² = .36). These findings indicate that workers are more likely to report errors when they feel safe to speak up, perceive systems as user-friendly, and experience manageable workloads. The study highlights the need for integrated interventions that simultaneously foster psychological safety, ergonomic system design, and balanced workload management to enhance proactive safety behavior in offshore environments. This research contributes to the intersection of industrial–organizational psychology and human factors engineering, emphasizing that safety performance in high-reliability organizations relies on both social and technological resilience. These findings align with Sustainable Development Goal 9 (Industry, Innovation and Infrastructure), reinforcing that resilient and sustainable industrial systems require the integration of human factors into safety management and system design.

PEMBERDAYAAN MASYARAKAT DESA CIPINANG MELALUI PROGRAM WATER CLOSET MANDIRI GUNA TINGKATKAN SANITASI CIPINANG [EMPOWERMENT OF CIPINANG VILLAGE COMMUNITY THROUGH THE PROGRAM OF INDEPENDENT WATER CLOSET TO IMPROVE CIPINANG'S SANITATION] Jack Widjajakusuma; Rudy Pramono; Adolf Parhusip; Reinhard Pinontoan; Nisvi Suciati Dewi; Siti N. Napilah; Aji Sulistian; Riska Apriliani; Nasya I. Arifa; M. U. Al-abqori; A.G. Hendra; A Hasyati
Jurnal Sinergitas PKM & CSR Vol. 5 No. 3 (2021): June
Publisher : Universitas Pelita Harapan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19166/jspc.v5i3.4984

The habit of open defecate of residents can pollute the environment and cause various sources of infectious diseases. Cipinang Village Community, District Angsana Pandeglang Regency still has a habit of defecating carelessly. Therefore, Pandeglang Regency Young Fighters in collaboration with Universitas Pelita Harapan in the frame of Community Service, trying to change the bad habit of open defecation of the Community in Cipinang by build Independent Water Closet Program. This program consists of three stages. The first stage is Socialization to increase awareness of the Cipinang Village community about the benefits and disadvantages of open defecation which is conducted in the hall of SDN 1 Cipinang. Second Stage is to build 5 units of adequate toilet facilities as a pilot unit. Stage Third, trigger and empower the community independently to develop toilet facilities by providing raw materials for the manufacture of latrines and septic tanks. The results is that the community in Cipinang Village already aware and have and knowledge about dangers and disadvantages of open defecation. BAHASA INDONESIA ABSTRACT: Kebiasaan buang air besar sembarangan (BABS) oleh penduduk dapat mencemari lingkungan dan menyebabkan berbagai sumber penyakit menular. Masyarakat Desa Cipinang, Kecamatan Angsana, Kabupaten Pandeglang masih mempunyai kebiasaan BABS. Oleh karena itu, Pejuang Muda Kabupaten Pandeglang bekerja sama dengan Universitas Pelita Harapan dalam rangka Pengabdian kepada Masyarakat berusaha mengubah kebiasaan buruk BABS dari masyarakat desa Cipinang dengan Program Water Closet Mandiri. Program Water Closet Mandiri terdiri dari tiga tahap. Tahap pertama meningkatkan kesadaran masyarakat Desa Cipinang tentang manfaat dan kerugian BABS melalui sosialisasi di Aula SDN 1 Cipinang. Hasil survey dan wawancara dengan masyarakat dalam sosialisasi ini menunjukkan bahwa masyarakat desa Cipinang sudah mempunyai kesadaran dan pengetahuan yang tinggi tentang bahaya dan kerugian BABS. Faktor yang memicu BABS ini adalah masyarakat tidak memiliki fasilitas toilet yang memadai karena tidak ada dana untuk membangun fasilitas tersebut. Tahap kedua adalah membangun 5 unit fasilitas toilet yang memadai sebagai unit percontohan. Tahap ketiga adalah memicu dan memberdayakan masyarakat secara mandiri dalam pembangunan fasilitas toilet dengan cara memberikan bahan baku pembuatan water closet dan septic tank. Pelaksanaan program dimulai sejak 16 - 29 Desember 2021 dengan sasaran 70 keluarga yang terdiri dari 6 kampung di Desa Cipinang. Dengan demikian, program ini dapat mengurangi kebiasaan BABS masyarakat Desa Cipinang dan berharap dapat memicu warga yang belum mendapat bahan baku pembuatan water closet dan septic tank membangun toilet yang memadai secara swadaya.

Title

Found 30 Documents
Search

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Title Search

Found 30 Documents Search

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Title

Found 30 Documents
Search