SAFETY MANAGEMENT DURING B UILDING DEMOLITION...Aparna Balasubramania Sharma B.Tech, Civil Engineering, SASTRA University, Thanjavu B.Tech, Civil Engineering, M.Tech, Civil Engineering,

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International Journal of Civil Engineering and Technology (IJCIET)Volume 8, Issue 7, July 2017, pp.

Available online at http://www.iaeme.com/IJCIET/issues.

ISSN Print: 0976-6308 and ISSN Online: 0976

© IAEME Publication

SAFETY MANAGEMENT

DEMOLITION

Assistant Professor

Associate Professor, SAS

Aparna Balasubramania Sharma

B.Tech, Civil Engineering, SASTRA University, Thanjavu

B.Tech, Civil Engineering,

M.Tech, Civil Engineering, SAS

ABSTRACT

Construction industry deals with the construction and maintenance of the

environment creating roads, dams, buildings and bridges. It consistently improves the

life of the people by upgrading the facilities for them. It

the world and plays a strong role in globalization.

Accidents are often recorded every year during construction and demolition. In

India, most of the structures are not demolished even after their life span. This is

unsafe for all the occupants of the old buildin

before the end of its service life on most of the other countries. Similarly demolition

should also be carried out wherever required in India keeping safety as of prime

importance. Thus Structures are to be demolishe

safety of the people residing in them and around so that accidents cannot happen.

For various renovation and rehabilitation projects, demolishing of structures is

done. Unplanned collapse of structures, exposure t

explosives, vibrations due to demolition affecting the adjacent structures and noise

pollution are some of the common risks involved in demolition.

The steps involved before demolition are proper pre

stability report and taking up the necessary safety measures.

This paper gives a brief description about the different types of mechanical and

chemical methods used for demolition. The need to manage the demolition waste has

led to environment friendly actio

construction. This paper provides insight about managing the debris produced due to

IJCIET/index.asp 358 [email protected]

International Journal of Civil Engineering and Technology (IJCIET) 2017, pp. 358–372, Article ID: IJCIET_08_07_039

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6308 and ISSN Online: 0976-6316

Scopus Indexed

ANAGEMENT DURING BUILDING

EMOLITION-A STUDY

Prof. D. Muthu

Assistant Professor, SASTRA University, Thanjavur, Tamil Nadu, India

Dr. C. Venkatasubramanian

Associate Professor, SASTRA University, Thanjavur, Tamil Nadu, India

Aparna Balasubramania Sharma

Civil Engineering, SASTRA University, Thanjavur, Tamil Nadu, India

Snehalatha S

B.Tech, Civil Engineering, SASTRA University, Thanjavur, Tamil Nadu, India

M Kazalli

Civil Engineering, SASTRA University, Thanjavur, Tamil Nadu, India



life of the people by upgrading the facilities for them. It employs many people all over

d and plays a strong role in globalization.



unsafe for all the occupants of the old building. Demolishing of the structure is done



Structures are to be demolished at the end of their design life for the



done. Unplanned collapse of structures, exposure to hazardous chemicals and


pollution are some of the common risks involved in demolition.

The steps involved before demolition are proper pre-planning, preparation of a

bility report and taking up the necessary safety measures.



led to environment friendly actions such as sustainable demolition and recycled


[email protected]

asp?JType=IJCIET&VType=8&IType=7

UILDING

avur, Tamil Nadu, India

Nadu, India

r, Tamil Nadu, India

TRA University, Thanjavur, Tamil Nadu, India

TRA University, Thanjavur, Tamil Nadu, India



employs many people all over



g. Demolishing of the structure is done



d at the end of their design life for the



o hazardous chemicals and


planning, preparation of a



ns such as sustainable demolition and recycled


Safety Management during Building Demolition-A Study

http://www.iaeme.com/IJCIET/index.asp 359 [email protected]

natural disasters and prevention of its impact on health of humans and the

environment.

This paper mainly helps to choose the right method for demolition, its key

objective being the safety of both the workers, occupants and the environment.

Key words: Demolition, Safety, Debris, Vibration.

Cite this Article: Muthu, Venkatasubramanian, Aparna Balasubramania Sharma,

Snehalatha S and M Kazalli.Safety Management during Building Demolition-A

Study.International Journal of Civil Engineering and Technology, 8(7), 2017, pp.

358–372.

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=7

1. INTRODUCTION

This paper “Safety management during building demolition” is done with the sole aim of

accomplishing safe building demolition. The demolition technique adopted depends upon

factors such as site condition, type of structure, age of building, height of building and cost

allotted for demolition. Most important factor for determining the method for demolition is

the surrounding environment and the structural stability. To reduce on the demolition wastage

in order to minimize the impact of the construction industry on the environment, the materials

obtained from demolition can be used for recycling.

By adopting the appropriate techniques for demolition depending upon the situation,

accidents are reduced with less environment impacts. The objective is to provide safety during

building demolition, to minimize the risk of injuries to people and properties, for the health

and safety of the workers on site, to reduce the impact on the neighborhood environment and

for safe removal of debris. Demolition poses a risk to not only the workers but also to

adjacent structures, their occupants and other people nearby.

Before initiating the demolition, proper pre planning and preparation of a stability report

will be handed out. After choosing the right method for demolition, it is carried out smoothly

along with all the safety requirements. In olden days small structures such as houses usually

consist of only two or three stories, demolishing them is rather an easy process. They are

pulled down manually or mechanically using hydraulic equipment mounted on cranes,

excavators or bulldozers and with the help of scaffoldings. Larger structures require the use of

wrecking ball, heavy weight on a cable that is swung by a crane into the sides of the building.

Nowadays numerous numbers of methods have come up such as cut and take down method,

hydrodemolition, demolition by explosives, demolition by non- explosive cracking agents etc.

Importance of Debris management should be realized and adopted everywhere, especially

before a predicted disaster. Dust management is essential and this plays a major role in air

pollution, therefore we should aim to manage and overcome it.

2. PRE DEMOLITION PROCESS

Every structure has an expiry year, existence of the building after its life is very

dangerous.Surveying of the building, structure and surrounding is carried out. The record

drawings and structural drawings are read and information regarding the construction

materials used, shared facilities with adjacent structures, sensitivity of the neighborhood with

respect to noise, dust and traffic is gathered, method of construction and deterioration of

structural elements are also obtained. Presence of chemicals, explosives or petroleum etc. is

noted or even if the building was previously used to store chemicals it is also taken into

consideration for soil analysis.

Muthu, Venkatasubramanian, Aparna Balasubramania Sharma, Snehalatha S and M Kazalli


Decisions are made about the method of demolition to be used and the types of

equipment, plant, labor etc. that has to be used will be analyzed. The plan in detail mentions

the sequential procedure of demolition and finally states the precautionary measures that will

be taken. It also mentions about their debris management plan as well.

A stability report is provided based on building administration regulation and it contains

the steps taken for the stability of the structure at different stages of demolition, Structural

calculations for requirement of temporary supports or bracing are stated and stability of the

adjoining structures and buildings are also reported along with calculations for the

requirement of temporary and permanent supports for these adjacent structures. Most

importantly it ensures that throughout the procedure, the margin of safety will be maintained

well within the limit.

Finally the safety precautions taken are reported which assures that the equipment are

inspected regularly, there is access to a properly connected power source, all flammable goods

are removed and firefighting appliances are maintained in good condition, only trained

workers with full safety measures are allowed to do the job, emergency exits are provided

during demolition, adjacent buildings are safe from the vibrations and that possible steps are

taken to reduce to impact on environment. Most importantly it contains the steps taken for the

safety of workers on site particularly against exposure to dust, chemicals, heat and noise.

Medical attention has to be also assured.

3. BASIC DEMOLITION METHODOLOGIES ADOPTED

Various methods for demolition have been adopted along with industrial evolution. The

following are some old and new methods applied in practice.

3.1. Jack Hammer

Figure 1 Jack Hammer

Jack hammers is a combination of hammer and chisel that are hand operated or machine

operated, powered by compressed air or electric motor. Nowadays they are mounted over

construction machineries such as excavators and cranes and are used for demolition by

hydraulic operation. This is called top- down method of demolition. The different types of

jackhammers used for demolition are Pneumatic, Electromechanical or Electro pneumatic and

Hydraulic. It if used for demolition of concrete, rocks and pavement. It is possible to remove

even the concrete with the rebar. It is the most economical method for demolition and thus it

can be used in projects where the initial cost is less. If the user is very skilled and strong,

he/she can support the weight of the tool and demolish easily. Sometimes two experienced

labors team up and finish the job quickly.

But the machine operation is noisy and creates micro cracks on the undamaged portion of

concrete. Vibrations will weaken the bond between undamaged concrete and increases the

chances for corrosion and damages in rebar. It also leaves behind 10-20 mm of dust making it



impossible to lay the new concrete over it because if it is done so, it will have very weak

bonding.

Scaffolding, netting and sheeting is provided for protecting nearby structures and people.

A normal building floor will not have the capacity to withstand the weight of a heavy crane

and the dismantled waste materials so they are reinforced first. For buildings having height 50

m or less, scaffolding is sufficient, but for buildings taller than that, construction elevator are

installed on the outside of the building. Water is splashed on the dismantled materials to

prevent the dust from spreading and efforts are taken for proper drainage of this water.

Periodical rest is essential for the user as the user is prone to injuries due to loud noise and

lack of blood circulation in fingers (white fingers) and he/she requires a break to breathe fresh

air due to the accumulation of dust. Workers are provided earmuffs and athletic tapes can be

applied which helps reduce the occurrence of white fingers. If proper precautions are not take

the workers are exposed to damage in tinnitus and carpal tunnel syndrome.

3.2. Road Milling Machines

Figure 2 Road Milling Machines

Pavement milling or cold planning is the process by which a part of the pavement is

removed up to any required depth. Most of the times engineers try to recycle the removed

materials reducing the impact of resurfacing on environment. Milling machine utilizes a large

rotating drum that removes and grinds the surface. It is used to remove raveling, bleeding,

rutting, shoring and other similar damages in concrete. It is also used to introduce camber on

roads and to perform grade adjustments for drainage purposes. This machine is comparatively

easier to work with and does not cause any discomfort to the operator. The depth of

demolition can be pre-set in advance and thus it is the best method for working on pavements

and roads.

But it creates noise pollution and micro cracks just like jackhammers and in addition to

that it does not reach under the rebar, therefore additional work should be performed to

remove the concrete under the rebar.

It also disturbs the bond between the undamaged portions of concrete and fails to keep the

rebar intact and just like jackhammers leaves behind 10-20 mm of thick dust on the concrete,

making it not possible to pave the new concrete over it. The cutters present in all milling

machines should be handled very carefully since they are very sharp. Only skilled labors has

to be allowed to operate it.



3.3. Water- Jet Hand Lance

Figure 3 Water- Jet Hand Lance

This is the simplest method that is used for demolition using water jets. The maximum

reaction force that can be created when used by hand is 250N and that when operated by

robots is from 1000N to 4000N [1]. It is especially used in areas where the confined concrete

is hard to reach. It does not create micro cracks and it can reach the concrete under the rebar

as well, thus reducing the work load. It also does not cause too much vibration like the above

methods, therefore it leaves the bonding within undamaged concrete in good condition and

rebar intact.

But depth cannot be pre-set like in milling machine and it is not an effective method due

to the noise pollution and more possibilities of injury to the operators. Only skilled labor are

to be allowed to operate it and they have to wear body armor, shin guards and metatarsals.

3.4. Hydrodemolition

Figure 4 Hydrodemolition

Hydrodemolition is a concrete removal technique which utilizes high pressure water for

the same. It efficiently gets rid of the damaged concrete by hydro blasting and paves a new

surface which appears irregular and craggy making the bonding with new concrete more

strong. It is a safer alternative to hand lancing wherein it overcomes all of its disadvantages.

This robotic concrete unit can be moved horizontally, vertically and at any inclined angle

making it easy to remove the concrete present at any confined place. It is 25 times faster than

the above methods and also very accurate. It is used in the rehabilitation and demolition

works of bridge decks, spillways, water treatment facilities, aqueducts, nuclear power plants,

warehouses, retaining walls etc. Deteriorated concrete can be selectively removed and

disposed unlike other methods where differentiation between good and bad concrete is not

possible. Vibrations will not affect the surrounding structures and rebar are not affected. Work

can be completed very fast and it minimizes dust pollution.



It is more expensive due to mobilization cost, limited availability of equipment, traffic

control, requirements for staged construction since it requires a larger area than it is required

in other methods therefore using it for minor works are uneconomical. The water pumps are

placed within 300ft from the repair area or if it’s a busy urban area, it is placed within the

structure. The pumps can run or diesel power which requires a separate fuel tank and exhaust

shaft or on electric power which is more expensive and requires a separate electric service

installed.

Local municipality water is used or water from lakes and ponds nearby are used. Using

recycled water is also a possibility but expensive. Waste water management is very important

so water after demolition can be sent to sanitary sewers or to the ground for absorption and

evaporation. But the pH of this water will be between 11 to 12.5 so they are treated till their

pH is within the range of 5-10. If the structure is badly deteriorated then using

hydrodemolition method for removal of damaged portion can lead to a full depth blow

through (i.e., complete cracking may occur throughout its depth). Shielding should be

provided to the undamaged portion in this case. If full depth blow through is predicted then

sound partition walls should be installed because it is extremely noisy (130 db). Sound waves

produced due to hydrodemolition are of low frequency therefore they can be controlled by

using partition walls made of dense materials such as sheet rock or concrete board. If they are

waterproof then they can help to contain the run-off water as well.

This machine is strong enough to cut concrete therefore it can obviously cut skin and even

bone. The operators always has to wear protective equipment like steel toed boots, eye

protection, ear muffs and hard hats for applying this method.

3.5. Top Down-Way Method

Italian company Despe came up with this idea. This method was implemented at first in the

demolition of Tour UAP, a 25-storey skyscraper in Lyon, France. Instead of wasting time on

scaffolding, they created an exoskeleton made up of steel platform covering the top three

floors alone within 20 days. This hat like scaffolding covered mainly the core at the center of

the building and they brought it down along with the reduction in size of building after

demolition of each floor. They followed the top down method of demolition and this is

accomplished by using various excavators mounted with jackhammers etc. Demolition takes

place so silently and smoothly that it is almost unnoticeable from outside. The workers are

allowed more access within the building and there is less noise and accumulation of debris.

Since each floor is demolished one after another from the top, it is easier to select the

materials for recycling and reuse. 95% of the building materials are recycled.

3.6. Kajima Cut and Takedown Method

Kajima Company, Japan came up with this method in April 2007 for safe demolition without

disturbing the nearby structures and the people residing in them. This is very useful especially

in crowded metropolitan areas.



Cutting Down of Column

Figure 5 Cutting Down of Column

Extending the Jack Stroke

Figure 6 Extending the Jack Stroke

Taking Down all the Jacks

Figure 7 Taking Down all the Jacks

Removing Beams and Floor Slab of the next Floor

Figure 8 Removing Beams and Floor Slab of the next Floor



The upper floors of the building are separated from the foundation thus leaving them

prone to risks due to earthquake forces and other wind forces (all lateral forces). To protect

them from crumbling down due to this, core walls are placed at the bottom floors. Core wall is

made of reinforced concrete box and is placed at the center of the building. The lateral loads

from the top floors are transferred to the core walls with the help of many detachable

temporary steel frames installed on the surrounding columns around the core wall. This is a

load transferring frame which transfers the lateral loads (earthquake forces) from the upper

floors to the core walls. During the demolition of floors, wedge controlling device will

disconnect this load transferring frame for smooth demolition. When earthquake or strong

lateral forces are predicted with the help of certain early warning signs installed in the

building, the wedges will immediately connect them back. Since most of the processes are

carried out in ground level itself, it reduces the risk of injuries due to falling materials from

demolition. It also increases the possibility of recycling and reusing since each floor is

demolished separately thus making it easier to segregate the reusable materials from others.

The process can be completed faster (approximately 15%) when compared to conventional

methods, which reduces the time taken and paves way for the immediate overlaying of

concrete. This process reduces the noises of demolition and also the dust dispersion. When a

building that is to be demolished is located in the center of a city then KC&TD method can be

used. They are more expensive and more time consuming than conventional method by 5-

10% but are safer and more recyclable.

3.7. Explosion Demolition

In this method the pillars, walls and other structural elements are removed to reduce the

stability of the building and thereby forcing it to collapse due to its own self weight.

Specialized operators called blasters are required in order to place the chargers in the right

position, to tear apart the critical sections of the structure.

Controlled demolition of building is called building implosion and this is achieved by

planning the placements of explosives, properly timing the explosion of each charge and

directing the fall of the building within its own footprint. Dynamites, RDX

(Cyclotrimethylenetrinitramine), water gel and emulsions are common explosives used.

Blasters try to find the minimum explosive charge required to explode the building by testing

it initially on few of the columns. This is done to minimize the flying debris and to avoid the

over-loading or under-loading of explosives. The columns will be well shielded during this

process.

Blasters find the critical supporting sections of the building and then plan their attack

accordingly. The pillars, walls and other structural elements are removed to reduce its stability

and thereby forcing it to collapse due to its own self weight. The columns in the lower floor

always carry most of the potential energy of the building so they are released first. In multi

storied buildings few explosives will be placed in some of the upper columns also.

Confining explosives within steel sections is not as easy as reinforced concrete columns

where holes can be easily drilled. Thus for steel flanges and webs, chevron shaped copper

elements filled with RDX explosives are used. For reinforced concrete columns, explosive

cartridges are placed within drilled holes which are balanced by stemming them with sand

bags.

In olden days a traditional fuse was used which will be filled with small quantity of

explosives. This long wire will be ignited at one end and it will burn at a constant pace till it

reaches the other end where a detonator will be placed for explosion. Now-a-days, blasters

use electrical detonator in which an electrical wire is used. Current is allowed to pass through



this wire and it heats up due to its resistance. This ignites the flammable substance on the

detonator on the other end of the wire, which in turn sets off the main explosives.

In reinforced concrete columns, after the detonation of explosives, the concrete

completely fragments leaving behind some of the reinforcing bars bent but intact. This will

retain their load bearing capacity and prevent the complete collapse of the structure. This is

avoided by properly identifying such columns in advance and separately exploding them and

cutting off the reinforcing bars before the rest of the structure.

Partial failure of an attempted implosion is very dangerous as the structure will now be

tilted at an unstable angle with the possibilities of prime explosive still being present within it

thus proving risky for the workers to enter the building without precautions. Shock waves can

travel sometimes outwards disturbing the nearby structure. Also the building crumbles down

as a massive heap, this makes it difficult to segregate the materials that can be used for

recycling which is very important nowadays to compensate the demolition cost and reduce

impact on environment.

Each column will be wrapped around by a geotextile fabric and they all will be linked

together using chain ropes to form a fence which will keep the large chunks of concrete from

flying out while the fabric prevents the small chunks. Explosive demolition is less expensive,

less time consuming and safe if necessary precautions are taken

3.8. Soundless Chemical Demolition Agents (or) Non Explosive Cracking Agents

SCDA’S originated back in 1890’s based on the investigation by Candlot and Michaelis about

the presence of ettringite in concrete. This product is not adopted everywhere because of the

lack of both guidelines and manufactures.

The composition of SCDA’s are CaO, SiO2 and/or cement. This powdery material

expands on mixing water, especially when placed under confinement due to the increase in

expansive pressure.

A layout plan containing details about the number of holes and the location of the holes

based on the demolition needs is designed and then the holes are drilled to the design depth

and diameter. The SCDA’s are immediately poured and mixed, with care within the holes.

Automatically the chemical reaction occurs and the rock/concrete will crack, it is then

mechanically removed after it reaches a suitable size. The parameters to be controlled during

the cracking mechanism are the time taken for the first crack in sample, cumulative crack

width at the end of 24 hours and the minimum demolition time (time taken to reach a crack

width of 25.4mm). This can be controlled with the help of three main parameters which

influence the generation of expansive pressure due to SCDA, The diameter and depth of

boreholes/holes, Temperature and Water content used for mixing.

The diameter of holes vary between 30-65 mm and the distance between holes are a

maximum of 100 cm and a minimum of 20 cm. depth of boring/holes should be 80-90% of

the depth of sample and the quantity of SCDA’s required for 1 m3 of concrete is 5-8 kg while

that for reinforced concrete is 15-25 kg.

Gomez and Mura came up with the relation L=DK, where L is the distance between holes,

D is the diameter of the holes and k is the constant based on in-situ property.

SCDA’s can work within a temperature range of -80C to 400C. Higher the temperature,

faster will b the cracking process. Thus recent studies show that the products used in cold

environments can be used in warm environments to increasing the speed of crack formation.

The water used for mixing should normally not exceed 150C and its ratio to the SCDA

powder is usually 1:3 by weight. Based on the research by Hinze and Brown we can conclude

that the expansive pressure and water content are inversely proportional.



Expansive grout is most commonly used and provides a good outcome. Non detonating

solutions, South Africa came up with Auto Stem (cracking agent) which is like a plastic

cartridge, it is pushed into a borehole just like a dynamite and when triggered electrically

using lead, a mix of material is produced in which the oxidizer reacts immediately to produce

a gas of very high pressure. Since the gas is contained within the borehole, it expands and

creates a pressure on the walls of the hole causing it to crack and thus splits the surrounding

materials also. The smallest 20 grams cartridge can break one cubic meter of stone.

This method can be only used in places where drilling of holes is possible. While

confining the agents in the boreholes, care is taken to ensure that it is not too tightly confined,

otherwise the pressure built up will be more and it can be harmful to the workers around. Also

this method involves skilled labors only as there is a possibility of steam explosion few hours

after placing slurry.

Workers need not excavate the area like in the case of explosives, they just have to stay 30

m away. Unlike explosive it does not heap the building into crumbles, but leaves them in big

chunks which can easily be reused or recycled. They are 20% more expensive than

explosives. They are safer compared to conventional explosives used because they do not

generate noise or explode into fly rocks. They generate minimal vibration and hardly any

toxic fumes. They mainly do not produce any shock waves and are used extensively in remote

mountain highways, concrete structures and roadways in inhabited areas and in other areas as

they are safe. Due to exposure to chemicals, care should be taken while using them.

4. GREEN DEMOLITION CONCEPTS AND SUSTAINABLE

DECONSTRUCTION

Green demolition is the concept that plans to maximize the environmental benefits at low

cost. It purely concentrates on the 3Rs: Reduce Recycle Reuse. The deconstruction survey

plays a vital role in green demolition by identifying the types and quantities of materials that

can be easily reused and recycled. It also recognizes the hazardous substances which may

cause issues during demolition process. In conventional methods nearly 80% of materials are

thrown as landfill waste. But in Green demolition method it is reduced to only 10% of

landfills. This method amplifies the reuse capacity by recognizing local reuse partners even

before the planning of demolition. It obviously increases the rate of reuse and recycle of

construction materials. As mentioned above it reduces all possible environmental impacts like

it reduces the noise and dust which arises during the demolition and affects adjacent

vegetation and habitat.

Green demolition costs a little more than conventional demolition but costs can be saved

by recycling some of the materials. This method acts as a step towards sustainable

development. LEED (Leadership in Energy and Environmental Designs) certification is

provided for those builders who attempt green construction and demolition.

5. RECYCLED CONSTRUCTION AND DEMOLITION WASTE

AGGREGATE FOR ROAD COURSE SURFACING

The main objective is to reuse, recycle and enhance the value of the wastes by utilizing them

for the development of other construction works. This paper highlights the usage of CDW in

road surfacing and the additional work that has to be done to accomplish it.

Netherlands has been reusing concrete and masonry as their base course from 1970’s.

The performance of sub base course materials made from recycled concrete and masonry

rubble were studied and it can be concluded that degree of compaction is the most important

factor among the mechanical characteristics of such base course. Sub base course increases



the optimum water content and decreases the maximum dry density of the sub base materials.

CBR value of recycled sub base is lower than that of natural sub base.

Firstly performance analysis is done based on three parameters dry density, moisture and

deflection. This is compared with that obtained from analysis of road surface made of quarry

aggregate. The analysis will always contain the characterization of the materials used for the

base layer of the surface course, the different materials used and their volume percentage in

the mix and finally treatment of materials.

Materials are washed manually and mechanically in order to remove plastics, paper and

wood. Using a backhoe excavator the metals are extracted and fed into the impact mill.

Materials more than 40 mm diameter are grinded. A test road with recycled CDW is to be

constructed and adjacent to it a road made on quarry aggregates is constructed. Their

performance based on deflection is analyzed after use. Results based on the experiment is

finally obtained.

Usually the compaction of CDW sub base course requires more water than quarry

aggregate. Its load bearing capacity will be satisfactory provided it does not include impurities

and contains only materials such as concrete, asphalt, ceramic etc. If the test show positive

and favorable results then it can be used for road pavements.

6. PLANNING OF DEBRIS MANAGEMENT

Disasters have become very frequent in the recent years. Increase in population has led to the

occupation of high risk zones by the people leading to loss in property and life due to major

debris generating disasters like hurricanes, earthquake, floods, tornadoes etc. The cost

required for cleaning up after these events is also very high.

Figure 9

Phase 1- Normal operation

It is defined as the period within which the debris management plan is developed which is

long before the occurrence of the disaster. The main focus at this time is to spread awareness

and the information is structured based on local experiences, limitations and capabilities.

Phase 2- Increased readiness

When a disaster is predicted, the existing plans are reviewed and updated. If the seriousness of

the event is more than what is expected and beyond the capabilities of local department of



Public Works and Department of Solid Waste Management then additional equipment and

manpower should be readied.

Phase 3- Response

After the debris generating event, the actions required to protect lives and property are

performed. Based on initial damage assessments the magnitude of damage can be determined

and the additional resources if required can be obtained from adjacent local governments and

other sources for aid.

Phase 4- Recovery

This phase can last for many weeks depending upon the damage created due to the debris

generating event. In this phase, removal and disposal actions will be continuously performed

till the pre disaster state is reached. This will be the most challenging phase to the debris

management staff especially if the affected sites were initially not considered a threat.

The debris generating management has to be always prepared for the next debris

generating event since this will reduce the cost and time associated with recovery of the area.

Even though debris management planning is very expensive, lack of its planning will have a

major negative impact especially on the economy of the area.

7. DEMOLITION DUST MANAGEMENT

Dust is an inevitable part of our everyday life. It is present in excess in construction site

especially during demolition. Demolition or even refurbishment work of particularly older

buildings can release fungal spores. Aspergillus (fungus) is the mould present in indoor

environment. People with very weak immune system and lung problems are prone to a lot of

diseases on inhaling these spores.

Precautions and care should be especially taken during demolition of buildings adjacent to

hospitals, leukemia patients housing and their families.

Dust commonly arises during demolition due to storages of finely divided materials such

as sand, cementatious products and wastes that are kept open, frequent passage of vehicles

and cleaning operations using sand blasting and sweeping.

Methods to control dust are by using dust collecting machineries such as sweepers. They

are not entirely safe as they splash a lot of dust into the surrounding during the sweeping

process using the sweeper trucks. Water suppression technique in which a water truck is used

to sprinkle water at regular intervals in the site, in order to prevent the escape of dust from the

ground is a more effective method. Screening and enclosure of fine particles (including waste)

will prevent them from mixing along with the air.

Dust screens called catch fans is used to cover the entire structure in order to minimize the

disturbance to nearby structures.

During the clean-up of dust, only completely accessorized workers should be allowed.

They should wear goggles, boots and masks since dust fumes can prove fatal to their lungs.

Dust management is an important objective for the principal contractor on site especially

in areas adjacent to hospital oncology, hematology departments and living accommodations

for leukemia patients. A monitoring program is overseen by an experienced air quality

professional and quick remedial measures should be provided when the dust present in air

exceeds the limit.



8. INFERENCE

Controlled demolition of building is necessary to ensure the safety of both the workers and the

surrounding in order to reduce the chances of accidents and impact on environment. Also the

materials obtained from demolition can be used for recycling in order to cut down on the

demolition wastage and cost.

Machines such as jackhammers and wrecking balls can be mounted on excavators and

cranes and can be used for demolition of all types of structures. More materials can be

recycled by this method than it can be done in the case of implosion. The materials can be

sold for re-use instead of as scrap. This method requires not only skilled operators but also

tough workmen because of the heavy equipment .This method creates a lot of pollution,

paving way to pulmonary and other lung related diseases. Jackhammer causes micro cracks

on the concrete surface. Rehabilitation is done to overcome this problem especially in

important structures like bridge decks. However they still manage to undergo extensive

cracking long before their design life.

Top down-way method acts as an improvised version of the former method with the new

idea of providing an exoskeleton cap. This overcomes many of the disadvantages of using

jackhammers such as noise pollution, dust dispersion and safety for the structures and people

residing nearby.

Rolling mills are the best equipment for roads and pavements, especially for asphalt roads

where recycled asphalt pavements can be easily laid.

Demolition by using water jet is an age old practice but it has to be done with care due to

the high force of water. Hydrodemolition is an advanced version of the same method which is

more efficient in every way. Unlike demolition by jackhammer, hydro-blasting leaves the

surface cleaner and the rebar remains corrosion free providing good bonding surface for the

new concrete. It can also segregate the deteriorated surface from the good one. It is more

expensive because of the space required for the big equipment such as pumps and motors

which in turn requires staged construction and traffic control. It requires large quantities of

potable water which is not ecofriendly and waste water management after demolition is once

again essential and expensive.

Cut and take down method is a very organized and systematic method where the

demolition is from the bottom to the top. Care is taken while placing the temporary supports

because they have to support the entire structure. Also core walls and lateral supporting

frames are to be placed to withstand the possible lateral forces. It is slightly more expensive

than conventional methods but more materials can be selected for recycling and it is more

suitable for busy urban areas.

For demolition by explosives, specialists are required to position the chargers in the right

places so that critical areas of the structure will weaken and the structure will demolish.

Controlled building demolition called implosion is safer for the people and the structures

around. The entire building explodes or implodes into a massive heap making it difficult to

segregate materials for recycling and increases the dust dispersion. Also controlling the flying

of debris is difficult.

Non explosive cracking agents overcome all of the above issues since they are noiseless,

produce less dust and reduce the structure into big chunks making it easier to reuse them. But

they can only be used in places where drilling holes is a possibility and they are not still an

upcoming field.

Debris management planning should be done for speedy recovery from disasters and it’s

after effects. Accumulation of debris and dust due to disasters, construction and demolition is



harmful for both humans and the environment. Inhaling them can cause pulmonary diseases

and other lung related diseases.

In order to improve the safety management during demolition, the right method for

demolition should be chosen based on various determining factors such as providing safety

for the workers and the adjacent structures, ensuring the removal of debris and reducing the

impact on environment.

9. CONCLUSIONS

In urban areas both top down-way method and bottom to top (cut and take down) method can

be used. Top down-way method can be used for structures within 50 m height because it

becomes difficult to take the cranes and excavators to the top of the building for which

additional construction of elevators have to be provided. Thus for taller buildings cut and take

down method can be utilized.

In places like quarries or structures located far from the city (outskirts) explosives can be

used for demolition since it is cheaper. Instead of explosion, implosion can be done which is

safer but in both cases materials cannot be used for recycling therefore it is preferred to use

non explosive cracking agents. This method will provide more materials for re-use and a

soundless, pollution-less demolition can be attained.

For small roads and pavements rolling mills are preferred, especially for repair works in

them.

Hydrodemolition will provide best results but it occupies a lot of space and is very

expensive. It also utilizes a lot of potable water which is not eco-friendly. Therefore it can be

used in very important structures like bridge decks etc. where quality of work is essential.

Civil engineers should choose the right method for demolition based on the sensitivity of

the environment. They should always try to accomplish sustainable deconstruction and reduce

the impact of the construction industry on the environment by giving importance to

management of debris during each demolition.

REFERENCES

[1] Bringing the house down [online]. (6 September. 2014). The Economist. The Economist

Newspaper Limited. http://www.economist.com/news/technology-quarterly/21615066-

new-ways-are-being-found-demolish-old-buildings-crowded-cities-bringing. [13 February

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[7] CTBUH Research Team Consults Prominent Demolition Experts. (17 July 2013). Council

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[9] Hydrodemolition Induced Cracking

https://www.nrc.gov/docs/ML1028/ML102871121.pdf.

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Documents

SAFETY MANAGEMENT DURING B UILDING DEMOLITION...Aparna Balasubramania Sharma B.Tech, Civil Engineering, SASTRA University, Thanjavu B.Tech, Civil Engineering, M.Tech, Civil Engineering,