Overview of Constructability Improvement through Innovations in Construction Methods during Construction Phase

What is constructability?

Construction Industry Institute (CII) defines 'constructability' is the "optimum utilization of knowledge and construction experience into the planning, design, procurement and construction phase to achieve overall project objectives". CII developed the concept constructability  in 1983, the Business Roundtable's Cicé conduct studies within 4 years to improve the quality, efficiency, productivity and compliance costs in the construction industry. The results are summarized in a report given the title "Integrating" (TCMC, 1991). Since that the CII at the University of Texas in the United States continued the research and establish local and regional groups to raise awareness about the benefits to be gained through constructability programs, such as improving the quality, reliability and cost-effective and time of the project.

CONSEPTUAL-> DESIGN->PROCUREMENT->CONSTRUCTION->START UP
Start----------------------------------------------------------------------------------------Complete

Fig.1 Project Life

Constructability concepts
In order to implement the concept of constructability CII (Buildability, UK) was made constructability program based of the seventeen concepts. Implementation starting from early stage is conceptual planning then design and procurement, and implementation on site.

The seventeen of the CII constructability concepts are as follows:

Conceptual Planning Phase:

1.      A formal constructability program is made an integral part of the project execution plans.

2.      Early project planning actively involves construction knowledge and experience.

3.      Construction personnel are involve in developing the project contracting strategy.

4.      Project schedules are sensitive to construction requirements.

5.      Basic design approaches Consider major construction methods Such as modularization or preassembly.

6.      Site layout promotes efficient construction

7.      Project Team Participants Responsible for constructability are Identified early in the project.

8.      Such advanced information technologies as 3D computer modeling or field notebook computers are applied.

Design and Procurement Phase:

9.     Design and construction procurement schedules are driven.

10.  Design are configured to enable efficient construction considering issues like simplicity, flexibility, sequencing of installation, and labor skills and availability.

11.  Design elements are standardized

12.  Construction efficiency is Considered in specification development.

13.  Preassembly modular design and are prepared to facilitate fabrication, transportation and installation.

14.  Construction design promotes accessibility of personnel. Materials, and equipment.

15.  Design facilitate fabrication, transportation, and installation.

16.  Design and construction sequencing system facilitates the turn over and star-up

Construction Phase:

17.  Innovative construction methods are use-Such as innovative sequencing of field tasks, or use of temporary construction system, or innovative use of construction equipment.

Radtke et al. (1993) Project Level Model proposes to streamline the implementation of constructability programs. Implementation programs divided into corporate and project programs. According to Radtke at level project program, first; compile constructability capabilities, second; planning for the implementation of constructability and third; implementation of constructability

Innovation in The Construction Methods
A single concept of constructability in the construction phase on site is:
'Constructability increased when performed  innovation in the construction methods '
Some sense of the term used for the purposes of this research that the term 'construction methods' is broad in scope and usually refers to the technical manner in which various construction resources are located. While the 'innovative construction methods' refers to the extraordinary  way that is unusually carried out to completion of construction and general creative undertaken to address challenges in the field. 'Innovation' can be discerning subjective in this term, an example adaptation to the developing of non-construction aspect for development purposes may also be said to be innovative (O'Connor and Davis, 1988).

O'Connor and Davis (1988) describe a method of Construction Innovation include activities at the implementation stage as the following:

1.      Innovation in determination of sequence work of project

2.      Innovations in the use of materials / temporary construction systems

3.      Innovations in carpentry tools (hand tools)

4.      Innovations in the equipment use for construction

5.      Constructor-optional preassembly

6.      Innovation in temporary facilities

7.      Options 'post-bid constructor' relationship with the layout, design and selection of permanent material.

Implementation Constructability Program in Indonesia
The Contributions construction industry in Indonesia to increase the welfare of society is very significant. Amount of labor which absorbed in the construction industries sector increased from 2.8 million in 1990 to 3.5 million in years 2000. World Bank Report (2001) released approximately 1.400 contractors is a member of the Intellectual Property Rights (Association of Construction Experts Indonesia) and 43.000 small and medium sized contractors are members of the Construction Association of Indonesia (GAPENSI). Therefore, efficiency is a relevant issue in efforts to increase the performance of the Indonesia’s contractors for survives.

In construction projects the use of knowledge and construction experience to all project activities will result in cost and time efficiencies, improved quality and safety (Jergeas and Put, 2001). The Construction Industry Cost Effectiveness (Cicé) Task Force on U.S. estimates that the increase constructability could be saved 10 to 20 times the cost of the program constructability (TCMC, 1991). Study of the Construction Industry Institute (CII) in "Constructability" report 1986 showed that the implementation of constructability programs for specific projects could be saved 6% to 10% of construction costs (TCMC, 1991). Furthermore a case study conducted by Russell et al. showed that the increase in constructability will decrease 5% to 10% of the entire project time (Trigunarsyah, 1999).

The Greatest influence on increasing the performance of project when apply constructability program in the conceptual planning stages, design and procurement (pre-construction). However, in the construction stage also can still efforts to increase constructability by performing “innovation of construction method", of course the contractor can still getting benefits by implemented constructability at this stage though not as much as in the planning, design and procurement stages.
Implement construction experience into the design is very low when the traditional approach used. Trigunarsyah (2002) concluded that the project delivery in Indonesia generally use the traditional approach in which contractors and consultants is taken by a separate contract, that system causing no any contractor involvement in providing inputs for planning and design concepts. Consequently the opportunity for cost savings is lost due to the possibility of a design that does not 'construct-able'. Of course this is an opportunity for contractors to conduct constructability improvement through innovation of construction methods in the construction phase of the project.

Contractors and consultants in Indonesia still has not been formally implementing constructability programs. As in Malaysia constructability implementation does not well integrated and understanding to the constructability still individualized, the study of West Port Highway project conducted by Nima et al. (2002) pointed this out. They may understand the importance of modularization,  pre-assembly and innovation of construction methods but it is not implemented in the integrated program. Many opportunities to improve the project performance are lost due to have not integration in constructability implementation.

The contractor may be doubt to performing innovation in construction methods for various reasons. Survey by Jergeas and Put (2001) described that some contractor doubt to make innovations in construction methods due to the three main constraints (perception): a) the fear of risk, b) fell it costly to do innovation, and c) it takes time to train site employees. But not least also some contractors who are motivated to perform an innovative  in the construction methods as some of them are The Catalic Delta Constructions (DCC) in innovation of materials/construction of a temporary system for project-Bridge Road in Columbia, Hazama Co. to innovation in use sliding form to build Silo and pre-assembly panel precast at cement plant project in Kalimantan.

From the owners perspective  may be implementation the constructability program during construction phase by conducting innovation of construction methods will contribute only a small benefit, not as much benefits as when if constructability implemented from pre-construction phase. From the perspective of the contractors applying the innovation of construction method is very important because at this stage the contractors role in to perform constructability improvement.

References: Anderson, Stuart D., “ Implementing Project Constructability: Design Problem  Civil Engineering”

Clough, Richard H., (1981), “Construction Contracting” John Wiley & Sons,Inc.
Jergeas, George, and John V. P., (2001), “Benefit of Constructability on Construction Project”, J. Constr. Mgmt., ASCE, 127
Nima, Mekdam A. et al., 2002, “Constructability Concept in West Port Highway in Malaysia”, J. Constr. Mgmt., ASCE, 128(4)
O’Connor, James T. and Victoria S. D., (1988), “Constructability Improvement During Field Operation” J. Constr. Mgmt., ASCE, 114(4), 549-563.
O’Connor, James T. and Tucker, R.L., (1986), “Industrial Project Constructability Improvement” J. Constr. Mgmt., ASCE, 112(1)
Radtke, M. W., and Russel, J. S., (1993), “Project Level Model Process for Imple-menting Constructability” J. Constr. Mgmt., ASCE
The Construction Management Committee, (1991), “Constructability and Construct- ability Programs: White Paper”, J. Constr. Mgmt., ASCE
Trigunarsyah, Bambang (1999), “ Implementing Constructability On Construction Industry In Indonesia”, Proposal Research, UI
Trigunarsyah, Bambang, (2002), “Constructability Practice Among Project Designers In Indonesia”, Journal Teknik Sipil Univ. Tarumanegara,
World Bank, (2001), “Indonesia Country Procurement Assesment Report Reforming the Public Procurement System” Report No.21 823.

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Brief History of Readymix Industry in Indonesia

Bagaimana sejatinya sejarah perkembangan 'beton siap pakai' atau readymix dimulai? Sejak ditemukannya cement pozzolan perkembangan penggunaan beton untuk struktur bangunan semakin pesat. Kebutuhan akan ketepatan pengiriman dan konsistensi mutu beton menjadi penting. Readymix adalah pilihannya.

Definisi Beton Siap Pakai atau Readymix Concrete menurut SNI 03-4433-1997/ASTM C94-96 adalah
Beton yang dicampur dalam mesin pengaduk stasioner atau truk mixer dan dikirim ke pemesan dalam keadaan plastis/belum mengeras.

SEJARAH

Pada Tahun 1930 beton siap pakai dalam skala industri pertama kali dibangun di Inggris. Kemudian pada tahun 1960-an permintaan Readymix berkembang pesat di Inggris dan juga negara-negara di Eropa  untuk pembangunan infrastruktur.

Di Indonesia penggunaan beton siap pakai (Ready-Mix Concrete) dalam skala bisnis pertama kali dimulai oleh PT. Jaya Readymix pada tahun 1972 di Jakarta untuk melayani proyek-proyek konstruksi yang mulai berkembang. Seiring dengan meningkatnya pertumbuhan konstruksi diawal tahun 1980-an bermunculan perusahan-perusahan beton siap pakai (RMC) lainnya, demikian juga di Jawa Timur khususnya di Surabaya.

Permintaan RMC menurun setelah terjadinya krisis moneter pada tahun 1998 karena proyek-proyek banyak menghentikan kegiatannya. Kegiatan pembangunan mulai meningkat kembali sejak tahun 2000. Sampai tahun 2006 permintaan RMC di Jawa Timur tumbuh rata-rata 15% per tahun dan pada tahun 2005 total volume kebutuhan beton di Jawa Timur mencapai 1.125.000 m3 dengan produksi rata-rata perbulan lebih kurang sebesar 94.000 m3. Bersambung....

*) Materi ini pernah penulis sampaikan di Kuliah Tamu di Universitas Kristen Petra Surabaya
dan Institute Teknologi Nasional Malang.

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Factors Affecting to High Cement Content in Concrete Mix Design

 

Introduction

Generally concrete ingredients consist cement, fine aggregate, coarse aggregate and solvent water. Some additional additive or other materials for increase the concrete performance.

In The project of Construction Road Sindhuli-Nepalthok Section 3 NEPAL the source of material aggregate is explored from the riverbed of Sunkhosi river from borrow pit sta. 1+000, sta 18+000, 29+500, 30+800 and others.

As known, Aggregate quality the thing important to produce of the economical concrete. It will influence cement content in the concrete.

Following a case study of factors affected to high cement content in mix design.

• Quality of Concrete Ingredients

Water : Well water located at side of Sunkoshi river. This water is acceptable for water mixing for concrete.

Cement : Pxxx Cement Grade-43

Mortar strength test results: for period April 2010 up to Dec 2010 the mortar stress tendency lower than specification refer to (Indian Standard) IS-8112.

In this case, necessary to increase cement into the mix proportion due to low quality of cement.

Fine Aggregate

The quality and properties of aggregate most important to get durability of concrete.

The Sunkoshi fine aggregate two matters to be concerned that the grading related to fineness modulus, and Mica.

1. Grading and Fineness Modulus (FM)

Fineness Modulus (FM) is the sum of cumulative percentages retained on sieves starting from size 0.15mm to maximum size divided by 100. It is note that a fine grading has a lower FM.

Variation for FM of Sunkoshi fine aggregate (washing screen plant) is too many variation. In Similar borrow pit has minimum value of FM is 1.91 and maximum value is 2.97, with standard deviation 0.29.

The grading is very important such that a reasonable workability and minimum segregation are obtained. A workability mixture can produce a strong and economical concrete.

However, a change in FM of 0.2 in fine aggregate may lead to a significant change of water demand for the same workability of concrete mixture. That is also will lead increased cement demand for keep strength (w/c).

2. Mica
Almost Fine aggregate from Sunkoshi River contains ‘mica’ with various content of mica. Some standard specification not clear yet how much mica content minimum will allow in fine aggregate. Some rumors says in German not allowed mica content in fine aggregate. So far, although not many research about effect mica in fine aggregate but of course mica in fine aggregate will effect to strength of concrete, that will contributed to cement demand in concrete.

The others parameter such as soundness, alkali reactivity are still in tolerance. In addition, sand equivalent, clay lump, washing loss, organic impurities may in tolerances because this fine aggregate is processed trough washing plant, except it not wash properly.

Coarse Aggregate
Table-2 below shown results of abrasion and elongation test for Sunkoshi coarse aggregate.

Table-2 Abrsion and Elongation of Coarse Agg. Sunkoshi
Kind of    Agg.       |    Surface    |   Abrasion        |   Elongation Index  |
Gravel                    |                   |    TS.40% max |       BS.25% max   |
Max. 40 mm          |   Smooth     |     36- 38%      |          30.0%          |
Max. 25 mm          |   Smooth     |     36 -40%      |          27.1%          |

Refer to table-2, elongation index of aggregates is more than 25 % and the surface aggregates is smooth. A note, elongation index of gravel40mm higher than gravel 25mm. Higher elongation will guide to increase sand aggregate ratio (S/a).

The stress at which the breaks developed depend largely on properties of the coarse aggregate; smooth gravel leads to breaking at lower stresses than rough and angular crushed rock, because mechanical bond is influenced by the surface properties and certain degree, by the shape (elongated) of the coarse aggregate. (Neville, properties of concrete 4th, 1995, p288)

Mix Proportion

The mixproportion of concrete for Nepalthok site are as follows;

Class Concrete      Targer Strength     W/c      S/A      Cement/m3
D1=40mm max            21.2 Mpa        55        40           327
D2=25mm max            21.2 Mpa        56        40           300

In General, the larger maximum size of aggregate used then the smaller value of sand aggregate ratio (s/a), it will smaller water demand in the same workability. That means, the larger maximum size of aggregate used is more economically (lower cement demand) than smaller size used.

But in this case, relation between aggregate maximum and S/A is conversely(see Table 3 and 4 above). For example: mix-proportion in Table-3, S/A for D1 (agg.40mm under) is equal D2 (agg.25mm under), the same water content 180 kg/cm3 at the same slump. In the same target strength cement content for D1 is bigger than D2. This reality probably cause by shape or elongated of aggregate.

• Concrete Production (Process)

During production of concrete, many factors may influent to strength of harden concrete.
Condition of mixer-pan or Truck Mixer for concrete mixing, variation of quality of aggregate, quality of cement and water, technician, making sample, curing etc., all of them will effect to variation quality of concrete.

• Conclusion

According to data above, mainly factors affecting high cement demand on concrete (mix-design) as following;

1. Quality of sand specially variation in grading, FM and Mica Content in fine aggregate.
2. High elongation and smooth surface of coarse aggregate
3. When low quality of Cement used, alone or together with quality of aggregate will contributed to concrete stress, and leads to increase cement demand to reach the target strength.

Nepal, Road Nepalthok-Shinduli Sec-III, 2010

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