Proceeding of the International Conference on Solid Waste Management

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In Bangladesh demolition of full building or structure is not very common. ... works produces huge amount of construction & demolition wastes (CDW) and ...
M Alamgir, QS Hossain, QH Bari, IM Rafizul, KMM Hasan, G Sarkar & MK Howlader (Eds.) ISBN: 978-984-33-0761-3, Vol. 2, pp.743-748

Proceedings of the International Conference on Solid Waste Management Technical, Environmental and Socio-economical Contexts - WasteSafe 2009 9 to 10 November 2009, Khulna, Bangladesh

Practice of Demolition Waste Management I. Saifullah1, S. M. K. Uddin1, A. Alam2 and Q. H. Bari1 1

Dept. of Civil Engineering, KUET, Khulna Project Engineer, M/S Jamal and Company Builders & Engineers, Dhaka

2

ABSTRACT Demolition is an engineering process by which a structure is destroyed for beneficial purposes. A questionnaire survey was carried out in Khulna city area. Data about the causes of demolition, its process and waste managing procedure were collected from Khulna. It is found that demolition of an existing building or part of it, for further development or renovation is very common in Khulna city. Demolition process usually creates wastes of engineering materials like floor finish and plaster dust (rubbish), pieces of concrete, bricks in regular or irregular shape etc. These are generally used for filling of low land, height raising the paving area etc. Regular maintenance and renovation of structures in KUET also produces huge amount of rubbish and its authority have been using these wastes for filling of low lying area. The paper focused mainly about the renovation and demolition waste generation and its utilization in Khulna city.

INTRODUCTION Demolition is the opposite of construction, the tearing-down of buildings and other component of structures (Allen 1993). In Bangladesh demolition of full building or structure is not very common. Hence the technology involved in the demolition of structure is not properly developed here. Recently, few works have been done in major cities and towns such as in Dhaka, Chittagong, and Khulna. Demolition is done for various reasons like old age of buildings, renovation, maintenance and repair, illegal construction etc. In Dhaka Rangs Bhaban (22 storied) is demolished for illegal construction by using manual and mechanical method. The company assigned in demolishing work did not have past experience of breaking such types of massive structure. Eventually accident was commenced there causing death of labors. Its clearly explains the lack of technology & expertise in this area in the country. In Khulna most of the building was demolished for several reasons: (i) exceeded design life; (ii) to construct new multi storey buildings; and (iii) to clear abandoned structure etc. For example Hotel Deluxe, Ajmal Plaza, G.M. Bakash Tower etc are demolished mainly for above causes. Table 1 shows the survey information of various demolished building site in Khulna, cause of demolition and techniques applied. In KUET, infrastructure development works continues for a long time which includes vertical extension of existing academic building, teacher’s quarters, student hall of residence etc. Vertical extension of building requires replacement of older roof slab by new one. Again regular maintenance of existing building is very common here as it is situated in the saline zone. All these works produces huge amount of construction & demolition wastes (CDW) and becomes a headache for disposing these in a safe way. There is enough low lying area in the campus which gives KUET authority to handle nicely to solve this problem. In addition KUET authority uses these wastes to prepare sub base of new roads.

METHODOLOGY AND TECHNIQUES A questionnaire survey was carried out and data from different building sites in the city area were collected. Annual repairing data were also collected from the KUET engineering office. Again land fill sites were visited by the authors and area was measured. There are various methods for demolition of structures; namely (i) Manual demolition; (ii) Engineered demolition; (iii) Demolition ball technique; (iv) Pusher arm technique; (v) Pressure jetting

for concrete repairs; (vi) Thermic lance technique; (vii) Microwaves technique; (viii) Concrete sawing. Suitable method is chosen from these depending upon the size, location, available space etc. Larger buildings may require the use of a wrecking ball, a heavy weight on a cable that is swung by a crane into the side of the buildings. Wrecking balls are especially effective against masonry, but are less easily controlled and often less efficient than other methods. Newer methods may use rotational hydraulic shears and silenced rock-breakers attached to excavators to cut or break through wood, steel and concrete (Liu 2003). Table 1 List of demolished buildings in Khulna

Buildings of

Hotel Deluxe Ajmal plaza G.M. Bakash Tower

Location Near

Reasons

Picture palace Picture palace

Design life exceeded Design life exceeded

No. of Date of Date of storey Proposed Procedure Starting Starting of Equipments before storey applied of new demolition demolition construction Hammer, 03 08 Jan-07 Manually Sani Hammer, 04 06 Jul-05 Manually Jan-06 sani

Basic Bank Multistory limited. purposes

01

10

Apr-07

Manually

Hammer, Sani

Feb-07

A. Hossain Plaza

City Bank Design life Limited (sir exceeded Iqbal road)

02

06

Apr-05

Manually

Hammer, Sani

-

Residential Building

Commerce Design life college exceeded

01

07

Feb-07

Manually

Hammer, Sani

-

National Tower

City Design life Law college exceeded

02

09

-

Manually

Hammer, Sani

Mar-07

Commercial Design life Hotel Royal Building exceeded

01

04

Jan-06

Manually

Hammer, Sani

Aug-06

01

O5

-

Manually

Hammer, Sani

-

02

02

April 07

Manually

Hammer, Sani

June 07

Residential 50, Cemetry abandoned Building road Slab of Damage Central old In KUET of roof slab library

CURRENT MANAGEMENT PRACTICE Before taking decision for demolishing of a structure, an assessment is carried out by a group of expert for institutional structure like structure in KUET campus, Cable factory etc. Institution or company usually involves engineers for making decision about renovation or demolition of their infrastructure. In case of public building, they decide their own on the basis of visual inspection and self judgment. For example, the decision for demolition of Hotel Deluxe is taken by the owners them selves. The institutional body invites contractor by open tender for maintenance and demolition works. While general people directly assign labors on daily basis for the same work. Demolition is not an easy task. In Bangladesh manual method is mostly used and mechanical method is hardly used. Traditional tools and equipments are used in manual method for chipping old plasters and breaking of parts of concrete. Tools like hammer, sani etc are frequently used for this purpose. A sequence of works is observed while demolitions proceed in a site. Its initially start by removing window and door panel. Next electric wiring and plumbing pipe is removed sequentially. Then breaking of the roof concrete and cutting of reinforcing bars is performed from one side of the slab as shown in Figures 1 and 2. Removal of plaster and masonry works is handled as sincerely as possible to separate each piece of brick in its original shape as shown in Figure 3. It can be used for other construction as a cheap recycle material. Finally beams and columns are demolished from the top floor of the building as shown in Figure 3 and 4. Initial storage of recovered reinforcing bars are shown in Figure 5 and storage of concrete & brick wastes are shown are shown in Figure 6. A list of construction wastes and its source of generation with further use is shown in Table 2.

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Figure 1 Demolition of Slab in progress

Figure 2 Mechanical cutting of slab

Figure 3 Demolition of brick works

Figure 4 Rubbish & concrete pieces

Figure 5 MS bars from demolished slab

Figure 6 Storage of C&D wastes

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A group of labors break together the structure and other group carries the materials outside of the building and dumps it in a predefined location. It is then carried to the site where it can be used by using men driven two wheeler curt (locally called thela gari), men driven tricycle carriage (called van gari), trucks etc. Table 2 Types and the probable uses of building renovation and demolition waste Sl. no. 1. 2.

Waste types

Sources

Further uses

Door, window of buildings Electric wiring Water supply & drainage system, toilet, kitchen

Repair & Reuse To reclying process

Building surface

Land filling

5.

Woods Electric wire Plumbing pipe, fittings Plaster & Floor finish (rubbish) Concrete piece

Slabs, beams, Columns etc

6.

MS rods

Slabs, beams, Columns etc

7.

Full size Brick

Masonry works, Partition wall

8.

Half brick

Masonry works, Partition wall

Land filling To reclying process as scrap, used for making nut ,bolt etc To use in masonry works, making khoa etc. Making khoa, Land filling,

3. 4.

To reclying process

MANAGEMENT PRACTICE IN KUET Huge low lying area gives an option to KUET authority to dispose and manage construction wastes easily. Before starting demolition and maintenance works the engineering office of KUET decides the locations for reclamation of low land by construction wastes. The area of the central play ground has been extended by dumping 12”-18” wastes as first layer and laying 12” soil as top layer is provided to have a smooth surface and to avoid any hazard caused by the sharp edge of the waste. In case of pond filling, the bottom 1m layer was filled by construction waste and then top 2-2.5m layer was covered with normal soil. They also use the waste for raising the height of land for connecting roads. They have done all these filling works successfully and not facing problems with those sites. Table 3 shows the different location and total volume of waste used in that site. All of this waste generated from either renovation, maintenance or demolition works inside the campus. Some times it becomes difficult to resolve the problem. For example, after disposing of a huge amount of waste it is hard to find new location this year to dump. Sometimes demolition and repairing contractor manage and find out a customer or they buy it directly. Situation can be worst and much critical when the demand for wastes to a customer less than the generated waste. In that case they offer the waste to someone for free of cost so as to clear the site. Table 3 Details of land filling sites in KUET campus Sl. No. 1.

Play ground East

Area 2 in m 3146

Volume of waste 3 in m 1133

2.

Civil Eng. Bldg. north

137

21

3.

Two ponds, Front of Canteen

850

1000

4.

Street near School, south

106

38

5.

Street near Mosque. south

67

24

6.

Street near MAR hall, east

133

48

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Location

Type of waste Rubbish Rubbish, brick & concrete pieces Rubbish, & concrete pieces Rubbish, brick & concrete pieces Rubbish, brick & concrete pieces Rubbish, brick & concrete pieces

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ADVANTAGE & DISADVANTAGE OF LAND FILLING Though land filling by construction waste is an option to manage these types of waste, it also has disadvantageous too. For instance it is greatly harmful if these are dump into the cultivable land (Weber and Jang 2000). Again it is mentioned by the people in the interview that they face problems for foundation construction of new building in the site previously filled by construction wastes. Because in that case it essential to clear the waste again from there. If these are used for filling area like new roads and for paving area systematically then it is more advantageous and do not affect soil environment.

FINANCIAL INVOLVEMENT IN DEMOLITION WORKS Resale value of an old building depends on some parameter such as age, size, material, & location of building. Cost of per square feet of floor is 30-35 tk. Demolition cost of per square feet is 35 percent of building cost. The expenditure of demolition depends upon the location & size of the structure, material of construction, skillness of workers and methods to be followed for demolition. As in Khulna city manual method is applied for most of the cases, the maximum cost goes for labor payment. Generally labors are paid on daily basis at the rate of 150-190 BDT /day. In some cases works are done by selecting on unit rate basis. The working efficiency and unit rate for demolished works of different items are shown in Table 4. Table 4: Demolition rate and working efficiency considered to evaluate demolition time Item Grade beam Wall Beams & Columns Slab CC works

Material

Volume of work (cft / 2person day)

Stone Brick Brick Stone Brick Stone Brick Brick

4-5 8-9 80-100 10-12 15-18 10-13 12-16 15-20

Rate of work BDT / cft 100-110 65- 70 10-12 80-90 55-60 20-25 18-22 20-25

Demolition wastes have salvage value as mentioned above. There are many vangary shops at sheik para area in Khulna city, which buy old reinforcing bars, sanitary pipes and fittings etc. Many people buy rubbish for land filling purposes. Cost of Rubbish depends upon the size of carriage. Selling price of demolition waste: Full Brick = 60% of new bricks Half brick (local name - adla) =20-25% of new brick. Rubbish=200~500 BDT per truck. Reinforcement =60-65%of original cost Ties and stirrup=500 BDT for 100 numbers.

RECOMMENDATION ON DEMOLITION PRACTICE The manual method is found to be more economic and creates less environmental problems as the noise generation is comparatively less. But it requires more time. On the other hand mechanical method is more costly and requires less time. However from close observation, it has been seen that the safety issues are ignored while demolishing a structure. Proper safety should be used in every demolition works for our own safety. In Dhaka, during the demolition of Rangs Bhaban proper safety has not taken. Twelve workers have lost their life due to poor safety measures during the works. More analysis on the suitable method for demolition of structure in Bangladesh is required. Further study could be carried out to develop models on efficient sequential demolition process and on waste generation.

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CONCLUSION The overall practice of demolition and renovation waste management in Bangladesh, especially in Khulna is satisfactory as most of the waste is reused by the different end users for different purposes. Nine buildings were safely demolished in Dakbangla area of Khulna since 2005 and the new buildings already have been constructed. Demolition rate varies from tk.10 to 110 per cubic feet depending on the type of structure component. A person can demolition concrete works 2 to 6 cft for stone aggregate and 4 to 8 cft for brick aggregate. The demolition practice in KUET campus is well managed. The renovation and demolition waste is disposed properly considering good safety measures.

REFERENCE Allen, R. T. L., Edwards, S. C. and Shaw, J. D. N. 1993. The Repair of Concrete Structures, Blackie Academic & Professional, Glasgow, UK. http://www.bangladeshobserver.com/ http://www.dailystar.net/ Liu, C., Pun, S. and Itoh, Y. 2003. Technical development for deconstruction management. Proc. 11th Rinker Inter. Conf. on Deconstruction and Materials Reuse, Gainesville, USA, 86-203. Weber, W.J., Jang, Y.C. 2000. Townsend, T.G. and Laux, S., Leachate from land disposed residential construction waste, Journal of Environmental Engineering. 128, 3, 237-245.

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