D19SC2 Construction Technology

Assignment 2007 – 08

                                

1.        INTRODUCTION

        Delivery a building project in the shortest possible construction time, with low maintenance cost and environmental awareness is still an increasingly complex and risky matters. A host of construction methods and management techniques have been promoted to help for achieve this. Choosing and tailoring the most appropriate construction method is a crucial task in the early stage of any construction project. The decision that will affect the relationships and risk allocation on a project.

             

2.        METHOD CONSTRUCTION

 2.1        Foundations

The use of precast concrete foundations can be beneficial to the base structure and are claimed to be available for medium-rise residential developments. Precast concrete foundation systems are specifically design to provide a moisture free and energy efficient living space for the home. Thus such systems result in the time and construction costs saving. However, engineering and geotechnical considerations will determine whether such a system is viable on a particular site. Varying building footprints and numbers of storeys will also need to be considered. (Appendix B – photo 1)

2.2        Superstructure

The use of Industrialised Building System (IBS) can reduce construction and maintenance costs, and improve safety by reducing hazards during construction period. It also reduces construction waste generation during construction. Industrialised Building System (IBS) is a method of construction can increase productivity and improve the quality of work through the use of better construction machinery, equipment, materials, and extensive pre-project planning; as well as to minimize dependency on unskilled foreign labour in the construction market. However, the choices for superstructure are wide and selections will be made against a range of criteria.

According to the theory of classification on Badir-Razali building system classification (Badir et al., 1998)[4] following three building systems are termed as Industrialised Building system (IBS):

(1) Cast in-situ formwork system – table or tunnel formwork system

(2) Prefabricated system – panel, block or frame system

(3) Composite system

The benefits of IBS are numerous:

  • Less on-site workers and trades.
  • Faster construction time.
  • Clean and tidy working environment.
  • Durability and reputability.
  • Dimensions accuracy.
  • Quality-controlled and highly aesthetic end-products.
  • Permitting off-site fabrication in factory conditions followed by scheduled and appropriate deliveries.
  • Cheaper total construction costs due to all of the above.

Figure 1 - Type of Industrialised Building system

 

2.2.1        Cast-In-Situ Building System

Cast in-situ building systems utilise lightweight prefabricated formwork made of steel/fiberglass/ aluminium in order to replace the existing conventional timber formwork. The objective of Cast-In-Situ Building System is to eliminate and reduce the traditional site-based trades like traditional timber formwork, brickwork, plastering and to reduce labour content. This method is suitable for large numbers of housing units that require repetitive utilisation of formwork. The formwork can be reused as many times as possible with minimal wastage. Careful planning of cast in-situ work can improve productivity, speed, and total cost (Ismail, 2001)[5].Its advantages over the traditional construction method include, low skill requirement, speedy construction, low maintenance, durable structure and less cost (Badir et al., 1998)[4.] (Appendix A – Catalogue)

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A.        Table Form

Table form is a large pre-assembled formwork and falsework unit, often forming a complete bay of suspended floor slab. It offers mobility and quick installation, fewer joints and better surface finishes. The table form method uses separate vertical forms for walls and horizontal table forms for floor slabs. The work is done in two stages. First, the walls are cast, and forms are stripped, the tables are then positioned, and the horizontal slabs are cast. Once the concrete has achieved sufficient strength, the formwork units are lowered, rolled out from underneath of the newly formed ...

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