Proposed residential redevelopment at Nga Tsin Wai Road

Proposed Residential Redevelopment at Nga Tsin Wai Road

Notable Features		Timber Formwork
Basic Information		Metal-Bamboo Matrix System Scaffold
Overview		Contact of Contractor
Waste Management

Notable Features

	Application of Metal-Bamboo Matrix System Scaffold
	Use of timber formwork
	On-site sorting of waste
	Reuse of steel hoarding
	Use of Gypsum base spray plaster
	Use of Auro paint

Basic Information

Location: Kowloon City

Building Type: Residential

Contract Period: 315 days

Gross Floor Area: approx. 2780m²

Client: Globpcc Development Ltd.

Architect: P&T Architects and Engineers Ltd.

Structural Engineer: P&T Architects and Engineers Ltd.

E&M Consultant: P&T (M&E) Ltd.

Quantity Surveyor: Levett & Bailey Chartered Quantity Surveyors

Main Contractor: Hsin Chong Construction (Asia) Ltd.

Contract Sum: HK$ 73,500,000

Overview

The Works comprised the construction of 6 residential units, each with a 5 storey height. The substructure comprised reinforced concrete columns and walls, ground beams and slabs. The superstructure was of reinforced concrete walls, columns, beams, staircases, suspended slabs and ramps. The external walls were of 100mm reinforced concrete finished externally with granite tiles and plaster. The internal partitions were generally of 100mm solid concrete block. The windows were generally of fluorocarbon aluminum frame and glazed with clear or obscured glass. The roofs were covered with asphalt on reinforcement cement and sand screed and finished with precast concrete tiles.

Waste Management

On-site sorting of waste

There was shortage of site space to install refuse chute. Waste materials were transported to the ground level by labourers or by tower crane. During the concreting stage there was no sorting of waste performed. Waste material in form of a mixture of rubble and small piece of timber was packed in bags and transported to the ground level by labourers. If sorting was to be performed, a large number of labourers would be required. During the finishing stage, cement, PVC, tile and packaging waste material were sorted out in bags and transported to the ground level either by labourers or by tower crane.

Material Control

For reinforcement and tiles where the materials were supplied by the main contractor, a bonus scheme was adopted to encourage the sub-contractor to minimise the wastage of material. Normally, 5% of wastage was allowed. A mock up flat was also used to estimate the quantity of tiles required. All material waste was minimised by close supervision.

Use of recycled materials

Gypsum base spray plaster

Auro paint

Reusable materials

steel hoarding

Timber Formwork

Timber formwork was used for this project due to the following reasons:

	There were several fins on the external walls.
	Tight programme and the low-rise blocks was to be constructed simultaneously.
	Lack out storage space for the steel formwork.

Metal-Bamboo Matrix System Scaffold

A new and systematic scaffolding ‘Metal-Bamboo Matrix System Scaffold’ was used for this project. The principal is the combination of both the characteristics of metal scaffolding and bamboo scaffolding. It comprises of steel pipes (60%) and bamboo poles (40%). All posts and ledgers are constructed with metal tubes. All braces are also metal tubes connected by clamps at 60^o subjected to different site situation.

Metal-Bamboo Matrix System Scaffold is composed of two layers similar to the traditional metal or bamboo scaffolding. For the outer layer, metal tubes are used as the main posts and main ledgers for maximum support, while bamboo is used as guardrail and fencing to minimise the loading and to increase its flexibility. For the inner layer, bamboo is used in areas with the transoms.

Together with other components, such as catwalks, toeboards and staircases, provides stable and safe working environment and accesses for workers working on it. The catwalks are made of aluminum while the toeboards are made of plastic. These materials can be reused and help to save the timber waste.

As for cost comparison, is about 15% higher than traditional bamboo scaffolding. The following table shows the comparison with traditional steel scaffolding and traditional bamboo scaffolding.

	Traditional steel scaffolding	New System	Traditional bamboo scaffolding
Catwalk	yes	yes	no
Toeboard	yes	yes	no
Stair access	yes	yes	no
High reliability	yes	yes	no
Flexibility	no	yes	yes
Light weight	no	yes	yes
High productivity	no	yes	yes
Minimum of costs	no	yes	yes

Contact of Contractor

Hsin Chong Construction (Asia) Ltd.

Hsin Chong Center, 107-109 Wai Yip

Street, Kwun Tong, Kowloon

Tel: (852) 2579 8238

Fax: (852) 2516 9430


	Low-Waste Buildings Technologies & Practices Home