FIRE RESISTING PROPERTIES OF COMMON BUILDING MTERIALS

Fire resisting properties of common building materials such as stone, brick, timber, cast-iron, glass, steel and concrete are mentioned below.

1. STONE

The stone is a bad conductor of heat. But it suffers appreciably under the effects of fire. The stone is also liable to disintegrate into small pieces when heated and suddenly cooled. Granite explodes and gets easily disintegrated in case of a fire. Limestone is easily crumbled even by ordinary fire. Sandstones of compact composition with fine grains can generally stand moderate fire successfully without the formation of serious cracks.

2. BRICKS

It is found that bricks are not seriously affected until very high temperature of 12000C to 13000 C are reached. This is due to the fact that a brick is a poor conductor of heat. If the type of mortar and quality of workmanship are good, brick masonry generally offers good resistance to fire. However, a brick has its own structural limitation for use in buildings.

3. TIMBER

As a general rule, structural elements made of timber ignite and get rapidly destroyed in case of fire. Further, they add to the intensity of fire. But timber used in heavy sections may attain a high degree of fire-resistance because timber is a very bad conductor of heat. This is the reason why time is required to build up sufficient heat so as to cause a flame in timber. In order to make timber more fire resistant, the surfaces of timber are sometimes coated with certain chemicals such as ammonium phosphate and sulphate, borax and boric acid, zinc chloride, etc. such a treatment on timber surfaces retards the rise of temperature during fire. The timber cam also be made fire-resistant by the application of certain paints on its surface.

4. CAST IRON

This material is rarely used as structural material at present. This material flies into pieces when heated and suddenly cooled. Hence, when this material is used in construction, it is covered either by brickwork of one brick thickness or any other fire resisting material such as concrete.

5. GLASS

This material is a poor conductor of heat and its expansion due to heat is small. Cracks are formed I this material when heated and then suddenly cooled. Reinforced glass with steel wire is ore fire-resistant than ordinary glass and it can resist sudden variation in temperature without the formation of cracks. Wired glass, even if it breaks, keeps the fractured glass in its original position.

6. STEEL

Steel is a good conductor of heat and hence, it is rapidly heated in case of fire. It is found that steel loses its tensile strength with the increase in heat and the yield stress of mild steel at 6000C is about one-third of its value at normal temperature. Hence, under intense fire, the unprotected steel beams sag, the unprotected steel columns buckle and the structure collapses. Steel completely melts at a temperature of 14000C. It is also found that if the surface paint is not specially made fire-resistant, it assists in spreading the flame on the surface and thereby it adds to the intensity of fire.

If steel plate or sheet form is fixed to framework, it becomes affective is resisting the passage of flame. Such construction is widely adopted in manufacturing fire-resisting doors and windows.

7. CONCRETE

Concrete has got very good fire resistance. The actual behaviour of concrete in case of fire depends upon the quality of cement and aggregates used. In case of reinforced concrete and prestressed concrete, it also depends upon the position of steel. Larger the concrete cover, better is the fire resistance of the member.
There is no loss in strength in concrete when it is heated up to 250°C. The reduction in strength starts if the temperature goes beyond 250°C. Normally reinforced concrete structures can resist fire for about one hour at a temperature of 1000°C. Hence cement concrete is ideally used fire resistant material.

HOW MANY TYPE OF STONE TEST

There are various kinds of lab and field tests available for building stones or rocks. These stone or rock tests are generally performed to determine the physical quality of stone materials used for construction work. Few tests such as Acid test may be performed to determine the chemical quality of building material or stones. Many of the known building stone & rock tests are explained briefly below:

. Hardness test

• Hardness is the resistance of a stone to indentation, rebound or scratch.
• It is tested by a pen knife with the aid of Moh’s scale of hardness.

Minerals	Moh’s Scale	Hardness test
Talc	1	easily scratched with the thumb-nail
Gypsum	2	scratched by the thumb-nail
Calcite/ Marbles	3	not scratched by thumb-nail but easily cut by knife
Fluorite	4	can be cut by knife with greater difficulty than calcite
Apatite	5	can be cut only with difficulty by knife
Orthoclase/ Feldspar	6	can be cut with knife with great difficulty on thin edges
Quartz	7	not scratched by steel, scratches glass
Topaz	8
Sapphire/ Corundum	9
Diamond	10

. Crushing test

• Three cube samples of size are cut and placed in water for 72 hours.
• They are tested in crushing test machine with loading 13.7 N/mm2 per minute.

3. Transverse strength test

• A specimen of the stone whose length is ten times its depth is placed on wedge-shaped supports near its ends. A vertical load applied at the centre is gradually increased until failure occurs. The transverse strength, called the modulus of rupture, in MPa is computed as

Where,

W = breaking load applied at the centre in N,

L = distance between the supports in mm,

b = width of the specimen block in mm and

d = depth of the specimen block in mm

• Transverse strength tests are usually made on specimens of 25mm square in section. The approximate values for ordinary stone are: Granite 10 – 17.5 MPa; limestone 3.5 – 20 MPa and sandstones in the range 4 – 15 MPa.

4. Impact test

• For toughness
• A steel hammer of 20 N is allowed to fall axially in the specimen.
• The blow at which the specimen breaks represents the toughness of the stone.

5. Fire resistance test

• The stone which is free from calcium carbonate can resist fire.
• Presence of calcium carbonate can be detected by few drops of dilute sulphuric acid which will produce bubbles.

6. Attrition test

• To determine the rate of wear of stones employed.
• Also known as abrasion test and is carried out in Deval’s Attrition Testing Machine.

7. Acid test

• Kept in solution of 1% H2SO4 or HCl and checked for deposits on surface.
• The stones having high percentage of lime content exhibit efflorescence when subjected to action of acids.

8. Porosity and water absorption test

• The porosity of the commonly used stones varies from 0 to 20%.
• The percentage of water absorbed by an air dried stone when immersed in water for 24 hours is termed as absorption of stone (air dry basis).
• A good building stone must absorb less than 5% water and those stones that absorb more than 10% of water should be rejected.
• Sandstones should not absorb water more than 10%, 17% in case of limestones and 1% in granites of their volume when dipped for 3-4 hours.

9. Smith’s test

• This test indicates the presence of earthy matter.

10. Crystallization test:

• To determine the durability or weathering quality of the stone.
• A sample of stone is immersed in solution of sodium sulphate at room temperature and dried in hot air.
• The process of wetting and drying is carried out for two hours; the difference in weight if any is recorded. Little difference in weight indicates durability and good weathering quality of the stones.

DANGERS ON THE CONSTRUCTION SITE

When you are exposed to any type of construction work, whether you are renovating your home or are in the business, safety should be the premiere concern. Construction sites are filled with danger and a common place for injuries so taking the right preventative measures will ensure the safety of all those concerned as well as the finishing of a project on time, safely and successfully.

1.       Make sure all employees and anyone that has access to the construction site wears proper protective materials. That includes hard hats, safety goggles, work boots, and proper attire. Make sure anyone that will be around the construction area is trained to look for dangers like loose nails, unsturdy ladders, and power tools. Construction sites are not playgrounds and children should not running around them without adult supervision.

2.       Debris and scattered materials can be the sneakiest forms of danger on a construction site. Make sure that the staff keeps the debris and trash to an absolute minimum and that everyone’s area is cleaned prior to leaving for lunch or for the day. Things like debris, loose wires, and garbage can lead to accidental injury even when people are not actually working.

3.     Protecting equipment will help keep it in the best condition for usage. Bad equipment creates a bad product as well as encroaching on the time a project takes to finish. Make sure tools and larger forms of equipment like bulldozers and cement trucks are updated and maintained. Exposed hoses are easy victims of construction site overlooking, but if they are ruined, it can prove time-consuming and disastrous to fix. Instead cover your hoses with a hose protector such as the ones seen on nayakcadd.blogspot.com. Having precarious equipment can put every person in the vicinity in danger at well as well as exposing you to liability.

QUALITY CONTROL AND SAFETY CONCERNS IN CONSTRUCTION

Quality control and Construction Safety represent increasingly important concerns for project managers.

Weak quality control leads to defects or failures in constructed facilities, thus result in very large costs. Even with minor defects, re-construction may be required and facility operations impaired. Increased costs and delays are the result. In the worst case, failures may cause personal injuries or fatalities. Accidents during the construction process can similarly result in personal injuries and large costs. Indirect costs of insurance, inspection and regulation are increasing rapidly due to these increased direct costs. Good project managers try to ensure that the job is done right the first time and that no major accidents occur on the project.

As with cost control, the most important decisions regarding the quality of a completed facility are made during the design and planning stages rather than during construction. It is during these preliminary stages that component configurations, material specifications and functional performance are decided. Quality control during construction consists largely of insuring conformance to these original design and planning decisions.

While conformance to existing design decisions is the primary focus of quality control, there are exceptions to this rule. First, unforeseen circumstances, incorrect design decisions or changes desired by an owner in the facility function may require re-evaluation of design decisions during the course of construction. While these changes may be motivated by the concern for quality, they represent occasions for re-design with all the attendant objectives and constraints. As a second case, some designs rely upon informed and appropriate decision making during the construction process itself. For example, some tunneling methods make decisions about the amount of shoring required at different locations based upon observation of soil conditions during the tunneling process. Since such decisions are based on better information concerning actual site conditions, the facility design may be more cost effective as a result.

With the attention to conformance as the measure of quality during the construction process, the specification of quality requirements in the design and contract documentation becomes extremely important. Quality requirements should be clear and verifiable, so that all parties in the project can understand the requirements for conformance. Much of the discussion in this chapter relates to the development and the implications of different quality requirements for construction as well as the issues associated with insuring conformance.

Safety during the construction project is also influenced in large part by decisions made during the planning and design process. Some designs or construction plans are inherently difficult and dangerous to implement, whereas other, comparable plans may considerably reduce the possibility of accidents. For example, clear separation of traffic from construction zones during roadway rehabilitation can greatly reduce the possibility of accidental collisions. Beyond these design decisions, safety largely depends upon education, vigilance and cooperation during the construction process. Workers should be constantly alert to the possibilities of accidents and avoid taken unnecessary risks.

RISKS IN CONSTRUCTION PROJECTS

Risks in construction projects may be classified in a number of ways. One form of risks classification is as follows:

1. Socioeconomic factors
   • Environmental protection
   • Public safety regulation
   • Economic instability
   • Exchange rate fluctuation
2. Organizational relationships
   • Contractual relations
   • Attitudes of participants
   • Communication
3. Technological problems
   • Design assumptions
   • Site conditions
   • Construction procedures
   • Construction occupational safety

The environmental protection movement has contributed to the uncertainty for construction because of the inability to know what will be required and how long it will take to obtain approval from the regulatory agencies. The requirements of continued re-evaluation of problems and the lack of definitive criteria which are practical have also resulted in added costs. Public safety regulations have similar effects, which have been most noticeable in the energy field involving nuclear power plants and coal mining. The situation has created constantly shifting guidelines for engineers, constructors and owners as projects move through the stages of planning to construction. These moving targets add a significant new dimension of uncertainty which can make it virtually impossible to schedule and complete work at budgeted cost. Economic conditions of the past decade have further reinforced the climate of uncertainty with high inflation and interest rates. The deregulation of financial institutions has also generated unanticipated problems related to the financing of construction.

TYPES OF COLUMN FAILURE:

TYPES OF COLUMN FAILURE:

Columns are the most important parts of a structure. They transfer loads of the structure to the surrounding soil through the foundations. So we need to build strong columns, otherwise, failure will occur.

Columns are built with two building materials, concrete and steel. Before designing the columns, civil engineers should calculate total stress due to live and dead load of the building. When the applied stress exceeds the permissible stress (calculated) the structure will fail.

In this article, different types of column failures are discussed.

COMPRESSION FAILURE:

When columns are axially loaded, the concrete and steel will experience some stresses. When the loads are greater in amount compared to the cross-sectional area of the column, the concrete and steel will reach the yield stress and failure will be starting without any later deformation.

In this type of failure, the material fails itself, not the whole column. This type of failure mostly occurs in shorter and wider columns. To avoid this, the column should be made with sufficient cross-sectional area compared to the allowable stress.

2. BUCKLING FAILURE:

Buckling failure generally occurs in long columns. Because they are very slender and their least lateral dimension is greater than 12. In such condition, the load carrying capacity of the column decreases very much.

The columns tend to become unstable and start buckling to sideward even under small loads.That means the concrete and steel reached their yield stress for even small loads and start failing due to lateral buckling.

This type of failures can be avoided by not constructing long columns of slenderness ratio greater than 30

Pile Foundations - Design & Constructio

In foundation practices, the main point of concern is bearing capacity of soil. Bearing capacity can be defined as the maximum load that can be carried by the soil strata. When the soil is strong enough that it can carry the whole load coming on it, then we use shallow foundation. Shallow foundations are usually used where hard soil strata is available at such a depth that construction of foundation is not too costly. If hard soil is available at deeper levels of earth, then there is a need of some source that can transfer the load of the structures on the deep hard soil strata. This source can be said to be as the deep foundation. Pile foundation is a type of foundation in which pile is usually used as the source to transfer the load to deep soil levels. Piles are long and slender members that transfer the load to hard soil ignoring the soil of low bearing capacity. Transfer of load depends on capacity of pile. There is a need that pile should be strong enough to transfer the whole load coming on it to underlying hard strata. For this purpose, pile design is usually given much consideration. Depending on the load, type of material is usually selected for the piles. Piles are usually made from following materials:

Timber Concrete Steel Composite pile Design Consideration of pile foundation: It is understood that pile is the basis for design of deep foundation. The very first step in the design of pile foundation is selection of right type of pile. Selection of type, length, & capacity of pile depends on following parameters: Soil condition Magnitude of load Construction of Pile Foundation In actual construction, first pile load test is performed on the soil to verify soil strength that whether it can take the load of pile or not. Factors which affect the selection of pile are as under: Length of pile in relation to load and soil condition Behavior of structure Availability of material in locality of construction Type of loading Ease of maintenance Availability of funds Factors causing damage Cost of piles Geo technical design of pile foundation: By geotechnical design we mean two things: Depth below the ground Dimensions The total load carried by the pile and its elements is said to be the ultimate load. It is usually denoted by 'Qu'. Load that can be carried by pile is due to its shaft and bearing resistance. Qu = QS + Qb Where QS is shaft resistance and Qb is bearing resistance Load Carrying Capacity of Piles Usually three methods are used for the calculating the capacity of pile: Static formula (this formula is applicable to driven and insitu piles) Dynamic formula (this formula is applicable to driven piles) Load Test (this test is usually done two times the design load. If it is stable then pile is considered O.K. This test is quite expensive and time consuming. Load application is also very much difficult in this test) Two more things which have importance in pile foundation design are: Pile spacing Negative skin friction

HOW TO BECOME SUCCESSFUL CIVIL ENGINEERS

From fresh running water to bridges, from pavements to the Olympic stadium — everything around us has in some way been influenced by civil engineering.

Employment in this field can really give you the opportunities to achieve what you want in life, offering both fantastic benefits and progression. If you’re interested in maths and physics, then the employment future of your dreams may just lie in civil engineering jobs, and construction estimators.

LEARNING THE ROPES

It is important to consider which pathway you take on your dream to becoming an engineer. You should plan for this from as early as your GCSEs and A Levels – where you should look to focus on mathematics and physics. There are other options, including becoming a civil engineering technician through a college BTEC course or apprenticeship. This will ultimately put you on the right path to becoming an officially accredited civil engineer.

In general, most civil engineers are required to have obtained a degree in civil engineering; the course usually takes between three and five years to complete. Among other disciplines, you’ll study design, mathematics, physics, project management as well as your desired top- up modules.

A degree, however, is only the first part of the process to becoming a professionally certified, chartered engineer. You must then complete a period of work experience as well as completing certain examinations. Certification varies between countries, which is something to bear in mind when deciding where you’d like to operate from. In the UK there are several places you can go to discuss work experience opportunities. Of course, there’s nothing to stop you either from approaching an employer directly to ask for an opportunity!

Many civil engineers choose to follow on from an undergraduate degree to a post-graduate degree which allows you to further specialise in your chosen field of interest.

BECOMING AN EXPERT

There are many sub-disciplines of civil engineering which will give you the chance to work across a variety of disciplines or, alternatively, to build your expertise in a particular area. Earthquake, coastal environmental, transport, urban or structural engineering are just a few types of civil engineering that you may think about specialising in.

Within the field there are different types of employers, such as regional contractors, local authorities (such as councils), consultancies and private clients. Each employer will require different levels of experience and will often work across specific sectors. There’s a common link between local authorities in cities and the requirement for urban engineering, for instance.

WHAT THE FUTURE HOLDS

Civil engineers can expect to earn anything up to £80,000 per year, with salaries generally starting around the £20,000 mark. You’ll spend time both on site and in-office maintaining projects from start to finish, making your workload both varied and challenging.

Civil engineering offers the scope to work abroad on an array of projects. Whether it’s structural engineering or providing the most basic of amenities, such as fresh water for locals, you’ll be able to find the opportunities of a lifetime to apply your skills overseas. You’ll be able to live the dream.

HOW MANY TYPES OF FLOORING TILES

TYPES OF FLOORING TILES

Flooring Tiles in India have over the years gained popularity over the cemented and concrete flooring Tiles are available in different patterns, designs and utility options. Usually they are costlier than the cement concrete flooring and its cost depends upon the type of tile being used.

Various types of flooring tiles used in India include the

• Terrazzo Tiles,
• Chequered Tiles
• Glazed Tiles
• Vitrified Tiles
• PVC Tiles

A wide variety of tiles are currently available in the market and the home owner has make a choice depending upon the finishing to be provided in the house, the location, local availability as well as the budget for putting up the floor.

1. TERRAZZO TILES

Terrazzo tiles

Terrazzo tiles are available in the market with sizes varying from 20 cm x 20 cm to 30 cm x 30 cm and thickness varying between 2 cm to 3 cm. Such tiles can be used in the living room, bed rooms etc as also in the treads and risers of the stairs.

The tiles are laid on the base concrete or RCC slab usually by providing a cement sand mortar of average 3 cm thickness. Before putting the tile on this mortar bed, they should be thoroughly cleaned and ultimately laid in the desired slope. Tiling should be done with care such that they are laid in a straight line. The floor should be kept wet for about 7 days and finally ground and polished as in the case of Terrazzo flooring.

It is advisable to keep some extra tiles in the house which may be required as and when some of them require replacement.

2. CHEQUERED TILES

Chequered Tiles

The chequered tiles are similar to the terrazzo tiles except that they have groves of about 2.5 cm in both directions. The method of laying such tiles is similar to that of laying other tiles. Care has to be taken to finish the grooves in a proper manner.

Chequered tiles can also be provided on the walls to give a different look. Usually they are costlier than the plain terrazzo tiles.

3. GLAZED TILES

Glazed tiles

Glazed tiles are available in the market having either a glossy finish or a mat finish. Tiles having a mat finish are usually provided in wet locations in the house like kitchen, bath, WC or in exterior locations like balconies etc to reduce the chances of slipping.

They are usually available in sizes of 10 cm x 10 cm, 15 cm x 15 cm or 10 cm x 20 cm in white or different colours. Tiles having patterns are also available in the market. They are laid in the same manner as any other type of tile. The joints between the tiles are flush pointed to give an even surface. Such tiles do not require grinding and/or polishing.

4. VITRIFIED TILES

Vitrified tiles are increasingly being adopted for construction of floors in residential buildings. They are quite sturdy and can be provided with equal ease both on a new surface and on existing flooring. Although they give a good look and can be cleaned easily, they are quite costly as compared to the other type of tile flooring.

Vitrified tiles are available in glossy or mat finish having different design and patterns. Sizes upto 60 cm x 60 cm are also available and accordingly each tile covers a large area. The flooring is provided in the same manner as that of other types of tiles, however care has to be taken to match the patterns while laying the same.

Vitrified Tile Flooring

5. PVC TILES

PVC tiles are being used for flooring in residential as well as non residential buildings. They can be provided for decorating the floors.

These tiles are costly and acoustically they have a superior performance although they are combustible. They are however easy to clean and maintain.

PVC tiles are usually square in shape having sides of 30 cm, 60 cm or 90 cm. Sheets and rolls of PVC are also available for providing larger floors These tiles are fixed to the floor tops with the help of adhesives, especially recommended for the purpose.

PVC tile flooring