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<![CDATA[Evaluating Liquefaction Phenomenon Of Silty Sand Using Piezocone Penetration Test (CPTu) ]]>
<![CDATA[Albert Johan]]>;
<![CDATA[Paulus Pramono Rahardjo]]>;
<![CDATA[Budijanto Widjaja]]>
<![CDATA[ U Karst Vol. 6 No. 1 (2022): APRIL ]]>
Publisher : <![CDATA[Kadiri University ]]>
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DOI: 10.30737/ukarst.v6i1.2118
<![CDATA[Most investigations into liquefaction have focused on clean sandy soils, with time, evidence has grown that liquefaction is often associated with silty sand material. Sibalaya Village, which suffered the greatest damage from the Palu-Donggala earthquake, is dominated by silty sand material. Related to this issue, an experimental study is conducted in the laboratory to understand the behavior of excess pore pressure and the strength of the saturated silty sand under dynamic loading. The experimental study uses several sets of testing apparatus such as a shake table, chamber, and CPTu. The shake table provides a dynamic load for the soil sample. The chamber allows the field environment to be duplicated in the laboratory. The CPTu measures excess pore pressure and strength of the soil sample. The test results show that liquefaction can occur in silty sand material. However, the fine-grain particles cannot generate the overall pore water pressure in which the pore water pressure ratio can only reach 93% of the initial effective vertical stress. Liquefaction also generates increased pore water pressure and a decrease in soil strength. The increase of dynamic load will result in a shorter liquefaction starting time, and fine content strongly influences the pore water pressure behavior, especially on the rate of pore water pressure dissipation after liquefaction occurs. Therefore, based on this research, it is known that silty sand material can experience liquefaction and can have a longer liquefaction period due to its lower permeability.]]>
<![CDATA[Identifying The Impact Of The COVID-19 Pandemic On The Indonesian Construction Sector Using The Exploratory Factor Analysis (EFA) ]]>
<![CDATA[Cecep Kamiludin]]>;
<![CDATA[Andreas F.V Roy]]>
<![CDATA[ U Karst Vol. 6 No. 1 (2022): APRIL ]]>
Publisher : <![CDATA[Kadiri University ]]>
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DOI: 10.30737/ukarst.v6i1.2147
<![CDATA[The COVID-19 pandemic has impacted Indonesia's construction sector. The growth of the construction sector severely declined due to the COVID-19 pandemic. However, the study of the impacts of the COVID-19 pandemic on the construction sector in Indonesia is still limited. The present study is aimed to examine the negative and positive impacts (opportunities) of the COVID-19 pandemic on the Indonesian construction sector. The study employed a quantitative approach with 128 contractors and consultants from 34 provinces in Indonesia. Through the factor analysis (EFA) and USG analysis approach, six negative and positive impacts of the COVID-19 pandemic and their priorities can be identified. The six negative impact factors are Workforce issues and Cost Overruns, Financial Performance Degradation, Project completion delays and schedule disruptions, Supply chain disruptions, Legal and contract issues, and  Difficulties in implementing health protocols and adjusting to the standard operating procedure. Meanwhile, the three positive impacts are Increasing awareness of the importance of occupational safety and health and collaboration among stakeholders, Improving the use of technology in the construction sector, and Optimizing existing procedures and systems. The study shows that the pandemic has impacted both the workforce and business entities' business Indonesian construction sector. These findings are expected to be useful in formulating strategic formulation for handling and mitigating the impact of pandemics.]]>
<![CDATA[Waste Concrete as a Substitute for Coarse Aggregate Materials for Compressive Strength of Concrete Fc' 20,75 MPa ]]>
<![CDATA[Bobby Damara]]>;
<![CDATA[Sugeng Dwi Hartantyo]]>
<![CDATA[ U Karst Vol. 6 No. 1 (2022): APRIL ]]>
Publisher : <![CDATA[Kadiri University ]]>
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DOI: 10.30737/ukarst.v6i1.2338
<![CDATA[Concrete from construction waste resulting from the construction of new infrastructure replacing old infrastructure can significantly impact the environment. Therefore, there is a need for the proper management of concrete waste. One of the uses of concrete waste is to use it as a coarse aggregate material in the manufacture of Concrete. Using waste concrete is obtaining a material that almost resembles coarse aggregate. This study aimed to determine the optimum content of Concrete with the addition of waste concrete as a substitute for coarse aggregate. This research refers to the standards of SNI and ASTM. The research was conducted by testing the waste concrete to determine whether it is suitable for coarse aggregate material. After that, the compressive strength was tested by curing for 28 days. This research was conducted with 3 samples with 0%, 50%, and 100% of the planned use of concrete waste with concrete compressive strength of Fc' 20,75 MPa. The results showed that the average compressive strength of the 50% concrete waste was 20.59 MPa, and the 100% concrete waste was 13.83 MPa. From these results, it can be seen that the most optimum content of substituted aggregate is a mixture variation of 50%, so the results of this study can be used as a reference in the utilization of recycled concrete waste as a raw material or a substitute for the composition of the concrete mixture.]]>
<![CDATA[Determining the Type Of Skybridge From The Bojonggede Station to The Bojonggede Terminal Considering The Traffic Impact ]]>
<![CDATA[Sofian Ari Saputra]]>;
<![CDATA[Rinda Karlinasari]]>;
<![CDATA[Rachmat Mudiyono]]>
<![CDATA[ U Karst Vol. 6 No. 1 (2022): APRIL ]]>
Publisher : <![CDATA[Kadiri University ]]>
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DOI: 10.30737/ukarst.v6i1.2386
<![CDATA[Bojonggede Station, located in Bogor Regency, is one of the KRL stations used to support the mobility of the surrounding community. This makes Bojonggede station a place with quite complex transportation problems. From the various problems that occur, this research aims to find the right sky bridge to connect the bojonggede station with the bojonggedeTerminall and reduce the impact of traffic in the surrounding location after the sky bridge. The data analysis method used is the 4 step model method consisting of trip generation/attraction, trip distribution, mode selection (Moda Split), trip assist, Indonesian road capacity manual, and descriptive analysis of survey data on visitors Bojonggede station. From the results of the analysis based on the 4 step model and manual of Indonesian road capacity, it is found that the performance of the Bojonggede 2 highway, which is in front of the location, has increased from LOS F during the construction period to LOS C during the sky bridge operations bridged. The benefit of this research is that it can be seen that traffic problems that occur at the study site can be overcome by the existence of an efficient sky bridge design sky bridges Bojonggede station with Bojonggede Terminal, to be further recommended to the Bogor district transportation office, and the Jabodetabek transportation management center ( BPTJ).]]>
<![CDATA[Cyclist Safety and Comfort of Bicycle Facilities in the Bintaro Jaya During Covid-19 Pandemic Using Bicycle Level of Service ]]>
<![CDATA[Fredy Jhon Philip Sitorus]]>;
<![CDATA[Galih Wulandari Subagyo]]>;
<![CDATA[Rio Yohanes Nikijuluw]]>
<![CDATA[ U Karst Vol. 6 No. 1 (2022): APRIL ]]>
Publisher : <![CDATA[Kadiri University ]]>
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DOI: 10.30737/ukarst.v6i1.2393
<![CDATA[Limited cycling facilities are one of the problems that often occur in urban areas in Indonesia, especially Bintaro Jaya, an area that cyclists often traverse during the COVID-19 period as it is today. The lack of service level of bicycle facilities on Jl. Boulevard Bintaro Jaya often causes bicycle users to feel less safe and comfortable during cycling. This study was conducted to know the service of bicycle facilities in Bintaro, especially on jl. Boulevard Bintaro Jaya. The most affecting factor of the service level of bicycle facilities in Bintaro is the high volume of traffic. One of the first steps to knowing the level of service of bicycle facilities is to analyze using the bicycle level of service (BLOS) method. In addition, a questionnaire will be conducted to determine the perception of bicycle facility users in Bintaro. Observations on traffic characteristics are carried out on weekdays and weekends, which are then to obtain BLOS data. Analysis was performed that BLOS values above 3.5 which mean the bike is not feasible for cyclists. The results concluded that the bicycle facilities in Bintaro Jaya are still not by the safety and comfort factors according to the BLOS method. To improve the safety and comfort of cyclists, the application of traffic calm such as speed hum is needed to reduce the impact of high traffic volume and high speed, repainting of markings and adding bicycle parking facilities.]]>
<![CDATA[Dimension Analysis Of The Emergency Spillway Of Tirawan Dam With The Application Of The System Dynamic Model ]]>
<![CDATA[Awan Risdiyanto]]>;
<![CDATA[Adi Prawito]]>
<![CDATA[ U Karst Vol. 6 No. 1 (2022): APRIL ]]>
Publisher : <![CDATA[Kadiri University ]]>
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DOI: 10.30737/ukarst.v6i1.2477
<![CDATA[Tirawan Dam emergency spillway is planned to be able to drain the initial flood discharge when the gate above the main spillway is closed so that there will be sufficient time to open the gate to pass the peak flood discharge through the spillway safely. The emergency spillway elevation is designed to accommodate maximum water as a natural reserve during the dry season. This study aims to analyze the factors that play a role in emergency spillway design in meeting the availability of optimal raw water storage and increasing the safety factor against flooding using a simulation modeling method with the help of the Vensim PLE program. The modeling is made in three stages. The first is the analysis of the system model, the second is the creation of a caustic diagram, and the third stage is the simulation of the model and scenario model. The simulation results of this model scenario obtained an effective emergency spillway elevation of +69.50 m and a width of 20 m. The spillway can pass the Q1000 design flood without the control gate operation with a freeboard of 0.41 m with a raw water reserve of 240,649.69 m3. From the simulation results, it is also known that the operation of the main spillway serves to add a safety factor to the discharge capacity of the flood discharge during an emergency condition and cannot be operated to optimize the reservoir.]]>
<![CDATA[Curtain Grouting To Reduce Seepage Foundation Access Road To The Top Of The Dam At Tugu Dam ]]>
<![CDATA[Supriono Supriono]]>;
<![CDATA[Agata Iwan Candra]]>;
<![CDATA[Yosef Cahyo Setianto Poernomo]]>;
<![CDATA[Mochammad Danara Indra Pradigta]]>
<![CDATA[ U Karst Vol. 6 No. 1 (2022): APRIL ]]>
Publisher : <![CDATA[Kadiri University ]]>
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DOI: 10.30737/ukarst.v6i1.2479
<![CDATA[The construction of a complementary access road to the top of the dam is to the left of the Tugu dam pedestal. Based on geological studies, it is feared that there is a potential for seepage that passes through the left pedestal through joints, fractures, and fault areas/rock layers below the foundation surface. To anticipate this, the allowable seepage requirement is the lugeon value (Lu) < 3. This study aims to determine the geological conditions and the amount of seepage before and after foundation repairs are carried out using the grouting method. The type of this research is field research, qualitative descriptive because this research tries to collect lugeon population and cement material absorbed into the rock from water pressure test and grouting injection work by grouping each type of hole, pilot hole, primary hole, secondary hole, tertiary hole, and check hole. The study results by taking rock cores found that the constituent rocks were volcanic breccia units and colluvial rocks. Furthermore, a water pressure test before grouting with a water passing value of (k) = 6.62E-05 to 4.73E-04 cm/sec or with a lugeon value (Lu) of 5.07 to 36.21. After repairing the foundation using rim curtain grouting, the seepage that occurs decreases with a water passing value (k) = 1.96E-05 to 3.03E-05 cm/sec or lugeon (Lu) 1.50 to 2.32, so the requirements the target value of Lu < 3 was achieved with the effectiveness in the good category.]]>
<![CDATA[Optimization of Compressive Strength and Porosity of Normal Concrete Using Fly Ash and Alkaline Activators ]]>
<![CDATA[Wahyu Kartini]]>;
<![CDATA[Made Dharma Astawa]]>;
<![CDATA[Hendra Setiawan]]>
<![CDATA[ U Karst Vol. 6 No. 1 (2022): APRIL ]]>
Publisher : <![CDATA[Kadiri University ]]>
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DOI: 10.30737/ukarst.v6i1.2481
<![CDATA[The use of cement in the concrete mix is the most expensive material. In the cement production process, there is CO2 emission into the air, which causes the greenhouse effect and global warming. So we need other materials as an alternative to reduce the use of cement by using by-products such as fly ash which is categorized as a Pozzolan material. In this study, fly ash was used with variations of 0%, 70%, 80%, 90%, 100%, water-cement ratio 0.4. Because fly ash does not have the same binding ability as cement, alkaline activators are needed, namely Sodium Silicate (Na2SiO3) and Sodium Hydroxide (NaOH) Â , with molarities of 6M and 8M. To determine the compressive strength of concrete, a compressive test was carried out at the age of 7 days and 28 days and a porosity test at the age of 28 days. The maximum compressive strength of concrete with fly ash content of 90% with a molarity of 6M and 8M. The age compressive strength has the same value. At the age of 7 days is 14.43 MPa. At the age of 28 days, it is 18.39 MPa. The greater the use of fly ash and molarity in concrete, the fewer pores in the concrete because the mixture is more concentrated and round, and the small particle size of fly ash can fill voids in the concrete.]]>
<![CDATA[Monitoring of Substructure Building of Suramadu Bridge Causeway Segment on Surabaya Side Based on Corrosion Level ]]>
<![CDATA[Ari Setijorini]]>;
<![CDATA[Anik Ratnaningsih]]>;
<![CDATA[Krisnamurti Krisnamurti]]>
<![CDATA[ U Karst Vol. 6 No. 1 (2022): APRIL ]]>
Publisher : <![CDATA[Kadiri University ]]>
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DOI: 10.30737/ukarst.v6i1.2499
<![CDATA[The structure of the steel pile foundation for the Suramadu Bridge crossroad is located in a corrosive marine area. Air humidity, rainwater, mud, or friction with other objects that cause the protective layer to peel off. Corrosion monitoring is carried out to determine the corrosion rate as one of the steps to prevent corrosion. This study aims to evaluate and monitor the bridge's structure Suramadu Causeway. The evaluation carried out includes observing the damage caused by corrosion. So that it will be known the cause of corrosion and the handling of corrosion protection in the building under the bridge, this study used primary and secondary data collection methods and visual observation of damage from routine inspections carried out. The observations show that the condition of the piles is filled with marine life in the tidal area, while for areas that have never been submerged the condition is quite good. The value of the condition of the structural elements at level 3 - 5, which requires protection on steel pillars that have suffered a lot of damage—handling that needs to be done in the Atmospheric zone and Splash zone / Tidal zone is recommended Recoating, Wrapping, HDPE Jacketing, Epoxy Grouting. In the Submerged zone and the Embedded zone, it is recommended that the Cathodic Protection be replaced (120 kg for 600 mm). So from the results of the research that has been done, it can be used as a study for the maintenance of the Suramadu bridge in preventing corrosion.]]>
<![CDATA[Optimizing Performance Asphalt Concrete Hot Rolled Sheet– Wearing Course (HRS-WC) Using Chitosan Powder ]]>
<![CDATA[Jenny Caroline]]>;
<![CDATA[Maritha Nilam Kusuma]]>
<![CDATA[ U Karst Vol. 6 No. 1 (2022): APRIL ]]>
Publisher : <![CDATA[Kadiri University ]]>
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DOI: 10.30737/ukarst.v6i1.2545
<![CDATA[Road quality is also affected by temperature and weather, leading to surface pavement deformation. It is necessary to improve the quality of the road pavement so that the quality of the road becomes more durable and stable. Hot Rolled Sheet – Wearing Course (HRS-WC) is flexible and has high durability. The natural mineral has been used as the filler for pavement construction. However, further research is necessary to obtain alternative and more sustainable materials. This study will discuss portland cement filler as a reference to compare filler replacement with chitosan powder (shellfish) based on the general specifications of the 2018 highway revision 3 division 6. Chitosan powder contains calcium oxide of 3.04% and silica oxide of 17.98%, which are similar to cement fillers. The composition of chitosan powder are 100%: 0%, 50%: 50%, 25%: 75%, and 0%: 100%. performance analysis is done through the marshall test. The results showed that the comparison of the use of the best chitosan powder was at the asphalt content of 7.3 with 50% : 50% with a marshall test value of 993.4 kg, flow 3.20 %, VMA 18.36%, VFB 72.01%, VIM 5.14, MQ 301.440 kg/mm. From the result which meets the requirement, the filler has shown quality improvement as an additional mixture according to (SNI 03-6723-2002). Hence still not optimal to replace portland cement because, from the value of the marshall test, portland cement has a higher marshall value than chitosan.]]>
