Comparative Analysis of Quality, Time and Cost of Using Semi-System Formwork with Aluminum Formwork in the
Osaka Riverview Apartment Project.
Rakhmadi Thoriq Fajar Sugiyono Faculty of Engineering Narotama University
[email protected]
Abstract
Technological developments at this time require construction suppliers in carrying out projects to be able to manage properly so that they are able to achieve the expected goals. Good management can make construction projects run efficiently and produce good quality as desired by the project owner (owner). Formwork work has a great influence on the duration of execution in concrete construction because the cycle of formwork work is related to concrete work. This research has a type of comparative research. This study compares the quality, cost, and time between the use of semi-system formwork and aluminum formwork. The data used in this study are primary data and secondary data. The primary data required are formwork material specifications, formwork material prices, formwork installation duration, floor plans and detailed structural drawings. Secondary data needed by journals and research with similar themes. From the results of the analysis of the quality, cost and time of the two types of formwork, it is found that both materials for the preparation of formwork have good quality. Semi-system formwork costs Rp 8,138,0002,381,11 while aluminum formwork costs Rp 8,298,860,888,11. The costs incurred for using the semi system are cheaper than using aluminum formwork with a difference of Rp. 160,858,506,72., the aluminum formwork method has a work budget of 1.9% higher than the semi-system method. The duration of installation of aluminum formwork is faster than semi-system formwork, with a total time required of only 7.5 months, while for semi-system formwork it takes 10 months to complete the installation of formwork using the semi-system method.
The semi system method has 25% longer processing time compared to the aluminum formwork method.
Keywords :
Cost, Formwork, Quality, Time.
1. Inroduction 1.1. Background
A construction project is an activity that can be planned that uses resources (inputs) such as money, labor, materials, and this construction project is carried out to get a benefit (benefits) or results (returns) in the future (Paparang et al., 2018). Technological developments at this time require construction suppliers in carrying out projects to be able to manage properly so that they are able to achieve the expected goals. Good management can make construction projects run efficiently and produce good quality as desired by the project owner.
The project owner (owner) has a desire that his project can run as planned and have good quality, the resources to be used in project implementation need to be planned properly to support its success. The implementation of construction projects can run efficiently and have good quality with one of the efforts in the selection of formwork methods in molding concrete. Formwork or formwork is an auxiliary means for molding concrete with different sizes, shapes, and positions. The types of formwork that are usually used in the implementation of construction projects are conventional formwork, semi-systems, and systems (Pratama, 2017).
The formwork method that will be used in project implementation needs to be planned properly because of the large procurement costs and also maintaining the quality of the concrete to be printed. Formwork work has a great influence on the duration of implementation in concrete construction because the formwork cycle is related to concrete work (Saraswati, 2012).
Based on the explanation described above, so the author intends to discuss the topic of "Comparative Analysis of Quality, Time and Cost of Using Semi-System Formwork with Aluminum Formwork in the Osaka Riverview Project"
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1.2. Formulation of the problem
Based on the description of the background above, the formulation of the problem can be made as follows:
1. How is the quality of the material used between the use of aluminum formwork and semi-system formwork?
2. What is the ratio of the time required to use the semi system formwork with aluminum formwork?
3. How much is the comparison for the installation cost between aluminum formwork and semi system formwork?
1.3. Purpose of Writing
This research certainly cannot be separated from the existence of a very positive goal, while the objectives of this research are:
1. Knowing the comparison of the installation time of aluminum formwork with semi system formwork.
2. Knowing the quality of the material from aluminum formwork with semi system formwork.
3. Knowing the comparison of the cost of implementing aluminum formwork with semi-system formwork.
1.4. Scope of problem
The limitations of the problem in writing this final project are as follows:
1. A study to compare the efficiency between aluminum formwork and semi-system formwork was carried out in the Osaka riverview project.
2. This study only reviews the structure of plates, beams, columns, and shearwalls.
3. The quality of the material to be reviewed is only between wood and aluminum and does not count the quality of other materials.
4. The duration of implementation only takes into account the installation time on the beam, slab, column and shearwall structures.
5. Not counting the time of unloading and fabrication.
6. The cost that is taken into account is only the cost of formwork material and installation only on the structure of plates, beams, columns, and shearwalls.
7. Does not calculate investment costs.
8. The area to be calculated for aluminum formwork and semi-system formwork is zone 3 and zone 6 from floor 1 to floor 31
2. Literature Review 2.1. Quality
Product quality is a product that complies with standardized specifications. According to Swastika (2020) quality is the achievement of a work process that is in accordance with a predetermined reference or method.
1. Workload
The previous formwork planning makes assumptions about the load that will be received by the formwork material. The data that will be used in calculating the load are as follows (Arditama, 2016):
a. Concrete load, q = volume of concrete x density of concrete b. Density of reinforced concrete q = 2400 Kg/ m³
c. Density of wet concrete q= 2500 Kg/m d. Live load, q= 200 Kg/m²
Live load includes the burden of workers and work equipment.
e. Shock load, q=100 Kg/m²
Shock load itself is a load that occurs as a result of working on concrete, namely the pounding when the concrete is poured into the formwork and the vibrations caused by the vibrator at the time of compaction of the concrete
2. Voltage Calculation
To calculate the stress of a formwork material, the equation 1 . is used
𝜎𝑙t = M/W (1)
Description:
𝜎𝑙t : allowable bending stress
M : Bending moment due to work load
W : The moment of resistance of the cross section to be calculated
In calculating the bending moment that occurs due to the workload, equation 2 and equation 3 . are used a. Calculation of moments for 2 supports
Mx = 1/8 . q . l² (2) b. Calculation of 3 or more places
Mx = 1/10 . q . l² (3) Description:
q = evenly distributed load per m² l = distance from axis to axis of support
To calculate the moment of resistance of a rectangular cross section, the equation 4 . is used Wx = 1/6.b.h² (4)
Description:
b = cross-sectional width h = cross-sectional height 3. Deflection Calculation
To determine the stiffness of a material used, it is necessary to know the amount of deflection that occurs, so equation 5 and equation 6 are used in calculating (Arditama, 2016).
a. To place it on 2 pedestals (1) b. To place it on 3 or more pedestals c. (2) Keterangan:
q = Load is evenly distributed per m² l = cross-sectional length
E = Modulus of elasticity of bearing I = moment of inertia of the cross section
The deflection that occurs in the material is not allowed to be more than the allowable deflection (Arditama, 2016). Ignoring displacement at the joint site, the deflection of a structure due to its own weight and constant load is limited as follows:
, for beams in unprotected construction
, for protected truss construction Keterangan:
: Deflection L : Rod distance
2.2. Budget Plan
The cost budget plan is a cost estimate based on the plan drawings and technical specifications that have been determined. Cost estimates have an impact on the successful implementation of construction projects (A, 2011). The cost budget plan needs to be calculated in detail for the unit price of work based on the index value or coefficient for the analysis of material costs and worker wages. The author in calculating the rab in this study uses the contractor's calculation method so that the data to be used in the calculation is the volume of work and the price of the work unit. The volume of work is obtained by calculating the volume of structural work from the drawings that have been obtained. The unit price of work is obtained based on interviews with experienced parties, namely contractors in analyzing the cost budget plan. The formula that will be used in calculating the Budget Plan (RAB), is as follows:
Budget Plan = Volume x Unit price
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2.3. Duration
The author in calculating and comparing the total duration required by using the type of formwork semi system with aluminum formwork. Duration is the time it takes to complete a job. The author in calculating the duration by doing a comparison between the total volume of work with total productivity. The author in getting the productivity of semi-system formwork installation with aluminum formwork is done by making observations in the field and conducting interviews with several parties related to formwork work.
2.4. Formwork
Formwork is a part of the implementation of concrete structures in construction projects. Concrete requires a good formwork (mold) to get the shape as planned. Formwork is a mold that is needed in the implementation of a construction project that must have sufficient strength and rigidity to hold the concrete and resist the pressures and vibrations that arise in the casting process without any shift from the specified dimensions and without any structural defects such as deflection and porous concrete (Salmani, 2019).
Formwork implementation is a job that will be done repeatedly for the High Rise Building Project so that it requires a large cost in the procurement of formwork. Formwork has a cost range of 40%-60% of the cost for concrete implementation or 10% of the total cost of implementing a construction project (Pratama, 2017). The formwork planning that will be used needs to be carefully planned in terms of costs, methods, and time so that the construction project can run efficiently.
2.5. Formwork material
1. WoodTimber in construction is used as formwork for reinforced concrete work. Good wood chosen as formwork is new wood, because the old wood has a higher absorption capacity and surface than the new wood and the prints have different surfaces (Rafik and Cahyani, 2017)
Tabel 1. Classification of wood in Indonesia No Kelas Kuat Berat Jenis
Keringudara (gr/cm³)
Kuat Lentur Mutlak (kg/cm²)
Kuat Tekan Mutlak (kg/cm²)
1 I > 0,9 > 100 > 650
2 II 0,90-0,60 1100-725 650-425
3 III 0,60-0,40 725-500 425-300
4 IV 0,40-0,30 500-360 300-215
5 V < 0,30 < 360 < 215
Source: PPKI years 1961.
Wood has a allowable stress which is divided into several classes and has the type of stress used according to the needs of a project.
Tabel 2. Wood allowable stress
No. Voltage Type
(kg/cm²)
Wood strength class
I II III
1. Flexibility parallel to fiber 150 100 75
2. Press = pull parallel to
fiber 130 85 60
3. Press perpendicular to the
fiber 40 25 15
4. Slide parallel to fiber 20 12 8
5. Modulus of Elasticity (E) 120.000 100.000 80.000 Source: PPKI years 1961.
2. Alumunium
Aluminum can benefit from being lighter in weight and less maintenance than steel. However, the more expensive price makes its use limited to objects that must be given a lightweight formwork and or its repetition can be used optimally (Wigbout, 1992)
The most suitable aluminum for a formwork is the Al-Mg-Si type (a mixture of magnesium and low silica content). Depending on the content of the alloy, the aluminum resistance is quite good, ranging from 250 - 400 N/mm2 , corrosion resistance is almost the same as pure aluminum, the hardness according to Binell is 750 - 1200 N/mm2 , and the elastic modulus is 70 - 75 N/mm2 . The mass weight is set at 2700 – 2800 kg/m3 (Wigbout, 1992).
Aluminum itself has a allowable stress of 46.54 mpa (Sucipta, 2016). This formwork is made of aluminum in the form of panels that can be used repeatedly up to 300 times (Wigbout, 1992).
3. Research Methods
This research has a type of comparative research. Comparative research has the meaning of comparative research. This research compares the quality, cost, and time of using semi-system formwork with aluminum formwork. The data used in this study is primary data. The primary data required are formwork material specifications, formwork material prices, formwork installation duration, floor plans and detailed structural drawings. The author in obtaining data by making observations and direct observations on construction projects.
The author also conducted interviews with parties related to formwork.
Tabel 3. Research Variabel
No. Independent Variabel Variabel Terikat
1 Quality
Concrete defects affect time efficiency (Swastika, 2020)
The relationship between implementation methods and costs (Andriyono, 2018)
2 Cost The implementation method affects the cost
Volume of work (Agustinus, 2016)
3 Time Time efficiency affects costs (Yanita, 2018)
The relationship between quality and work time (Swastika, 2020) Source: Analysis Results (2021).
4. Results And Discussion
4.1. Calculation of formwork requirements
Tabel 4. Recapitulation of formwork area requirements No. Struktur Large Unit
1 Kolom 12156.9 m²
2 Shearwall 7140.4 m²
3 Pelat 16302.9 m²
4 Balok 12982.8 m²
Total 48583.1 m²
Source: Analysis Results (2021).
Based on the calculation of the total formwork requirement, a recapitulation of formwork requirements is obtained in zone 3 and zone 6 from floors 1 to 31 with a formwork requirement of 48583.1 m².
4.2. Quality calculation
1. Semi sistem FormworkThe author will give an example of calculating the strength of the material used in the column structure, along with the calculation:
Column length = 1 meter = 100 cm Column width = 0.4 meters = 40 cm Column height = 2.45 meters = 245 cm
Wood = 100 kg/cm²
E Wood =100000 kg/cm² Density of concrete = 2400 Kg/m³ Density of wood = 800 Kg/ m³ Hollow distance = 0.2 meters = 20 cm
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M = 1655 kg.cm
W = 130,68 cm³
σ = 12,66 kg/cm² < 100 kg/cm² (σ ijin kayu)….(Oke)
I = 118,59 cm4
= 0,006 cm < L/500
= 0,006 < 20/500
= 0,006 < 0,04 ……(Oke)
2. Alumunium formwork
The author will give an example of calculating the strength of the material used in the column structure, the following is the calculation:
Column length = 1 meter = 100 cm Column width = 0.4 meters = 40 cm Column height = 2.45 meters = 245 cm Aluminum = 46.54 Mpa = 474.71 kg/cm² E Aluminum = 70 N/m = 713790 kg/cm² Density of concrete = 2400 Kg/m³ BJ Aluminum = 2700 Kg/ m³ Panel Width = 0.4 m = 40 cm
q = 3262,4 Kg/m = 32,62 Kg/cm
M = 1631 kg.cm
W = 130,68 cm³
σ = 12,48 kg/cm² < 100 kg/cm² (σ ijin kayu)….(Oke) I = 118,59 cm4
= 0,006 cm < L/500 = 0,006 < 20/500
= 0,006 < 0,04 ……(Oke) 3. Installation Duration
Tabel 5. Recapitulation of the duration of formwork installation No. Formwork Method Time (Day) Time (Month)
1 Semi Sistem 303.6 10
2 Alumunium 221 7.4
Source: Analysis Results (2021).
Based on the results of the calculations and recapitulation above, it can be seen that the duration of installation of aluminum formwork is faster than semi-system formwork, with a total time required of only 7.5 months, while for semi-system formwork it takes 10 months to complete the installation of formwork using the semi-system method.
4. Budget Plan
Tabel 6. Formwork installation cost recapitulation
Indikator Semi Sistem Alumunium Formwork
Harga Satuan Rp 167,507.50 Rp 172,518.00 Total Biaya Rp 8,138,002,381.33 Rp 8.381.452.087,05 Source: Analysis Results (2021).
Based on the calculations and recapitulation above, the cost required to use semi-system formwork is Rp.
8.138.002.381.33, while for aluminum formwork it is Rp. 8.381.452.087.05. The costs incurred to use the semi system are cheaper than the cost of installing aluminum formwork with a difference of Rp. 243,449,706.
5. Conclusion
Based on the results of the analysis conducted on the comparison of quality, cost and time between the use of semi-system formwork and aluminum formwork methods on the Osaka Riverview project, the following conclusions were obtained:
1. The quality of the material used for aluminum formwork with semi system formwork has good quality and is strong for use in concrete molds.
2. The duration of installation of aluminum formwork is faster than that of semi-system formwork, with a total time required of only 7.5 months, while for semi-system formwork it takes 10 months to complete the installation of formwork.
3. The cost required to use semi-system formwork is Rp. 8,138.002,381.33, while for aluminum formwork it is Rp. 8,381,452,087. The costs incurred to use the semi system are cheaper than the cost of installing aluminum formwork with a difference of Rp. 243,449,706.
6. Recommendation
Based on the results of the analysis conducted on the comparison of quality, cost and time between the use of semi-system formwork and aluminum formwork methods on the Osaka Riverview project, the following suggestions were obtained:
1. Aluminum formwork should be used for High Rise Buildings which have a typical floor in terms of installation time of aluminum formwork 2.5 months faster than using semi-system formwork.
2. Semi system formwork is more affordable in terms of cost than using aluminum formwork but semi system formwork itself is slower in terms of time than aluminum formwork
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