CE2203 –CONSTRUCTION TECHNIQUES EQUIPMENTS AND PRACTICES III SEMESTER E-LEARNING MATERIAL
BY S.THAHIRA BANU., ASSISTANT PROFESSOR DEPARTMENT OF CIVIL ENGINEERING NPR COLLEGE OF ENGINEERING & TECHNOLOGY
CE2203 –CONSTRUCTION TECHNIQUES EQUIPMENTS AND PRACTICES
OBJECTIVE The main objective of this course is to make the student aware of the various construction techniques, practices and the equipment needed for different types of construction activities. At the end of this course the student shall have a reasonable knowledge about the various construction procedures for sub to super structure and also the equipment needed for construction of various types of structures from foundation to super structure. UNIT I CONCRETE TECHNOLOGY Cements – Grade of cements - manufacture of cement – concrete chemicals and Applications – Mix design concept – mix design as per BIS & ACI methods – manufacturing of concrete – Batching – mixing – transporting – placing – compaction of concrete – curing and finishing. Testing of fresh and hardened concrete – quality of concrete - Non – destructive testing. UNIT II CONSTRUCTION PRACTICES Specifications, details and sequence of activities and construction co-ordination – Site Clearance – Marking – Earthwork - masonry – stone masonry – Bond in masonry - concrete hollow block masonry – flooring – damp proof courses – construction joints – movement and expansion joints – pre cast pavements – Building foundations – basements – temporary shed – centering and shuttering – slip forms – scaffoldings – de-shuttering forms – Fabrication and erection of steel trusses – frames – braced domes – laying brick –– weather and water proof – roof finishes – acoustic and fire protection. UNIT III SUB STRUCTURE CONSTRUCTION Techniques of Box jacking – Pipe Jacking -under water construction of diaphragm walls and basement-Tunneling techniques – Piling techniques - well and caisson - sinking cofferdam – cable anchoring and grouting-driving diaphragm walls, sheet piles - shoring for deep cutting – well points -Dewatering and stand by Plant equipment for underground open excavation. UNIT IV SUPER STRUCTURE CONSTRUCTION Launching girders, bridge decks, off shore platforms – special forms for shells - techniques for heavy decks – in-situ pre-stressing in high rise structures, Material handling - erecting light weight components on tall structures - Support structure for heavy Equipment and conveyors –Erection of articulated structures, braced domes and space decks. UNIT V CONSTRUCTION EQUIPMENT Selection of equipment for earth work - earth moving operations - types of earthwork equipment - tractors, motor graders, scrapers, front end waders, earth movers – Equipment
for foundation and pile driving. Equipment for compaction, batching and mixing and concreting - Equipment for material handling and erection of structures - Equipment for dredging, trenching, tunneling, TEXT BOOKS 1. Peurifoy, R.L., Ledbetter, W.B. and Schexnayder, C., "Construction Planning, Equipment and Methods", 5th Edition, McGraw Hill, Singapore, 1995. 2. Arora S.P. and Bindra S.P., Building Construction, Planning Techniques and Method of Construction, Dhanpat Rai and Sons, 1997. 3. Varghese , P.C. Building construction, Prentice Hall of India Pvt. Ltd, New Delhi, 2007. 4. Sheety, M.S, Concrete Technology, Theory and Practice, S. Chand and Company Ltd, New Delhi, 2005. REFERENCES 1. Jha J and Sinha S.K., Construction and Foundation Engineering, Khanna Publishers, 1993. 2. Sharma S.C. “Construction Equipment and Management”, Khanna Publishers New Delhi, 1988. 3. Deodhar, S.V. “Construction Equipment and Job Planning”, Khanna Publishers, New Delhi, 1988. 4. Dr. Mahesh Varma, “Construction Equipment and its Planning and Application”, Metropolitan Book Company, New Delhi-, 1983. 5. Gambhir, M.L, Concrete Technology, Tata McGraw – Hill Publishing Company Ltd, New Delhi, 2004
UNIT I CONCRETE TECHNOLOGY Cements – Grade of cements - manufacture of cement – concrete chemicals and Applications – Mix design concept – mix design as per BIS & ACI methods – manufacturing of concrete – Batching – mixing – transporting – placing – compaction of concrete – curing and finishing. Testing of fresh and hardened concrete – quality of concrete - Non – destructive testing. TYPES OF CEMENT Ordinary Portland cement OPC33,OPC43 and OPC53 grade Rapid hardening cement Extra rapid hardening cement Sulphate resisting cement Portland slag cement Quick setting cement Low heat cement Portland pazzolona cement Air entraining cement Colored cement White cement
Hydrophobic cement Masonry cement expansive cement Oil well cement Concrete sleeper grade cement High alumina cement Very high strength cement CHEMICAL ADMIXTURES OF CONCRETE Water-reducing admixture / Plasticizers: These admixtures are used for following purposes: 1. To achieve a higher strength by decreasing the water cement ratio at the same workability as an admixture free mix. 2. To achieve the same workability by decreasing the cement content so as to reduce the heat of hydration in mass concrete. 3. To increase the workability so as to ease placing in accessible locations 4. Water reduction more than 5% but less than 12% Actions involved: 1. Dispersion: Surface active agents alter the physic chemical forces at the interface. They are adsorbed on the cement particles, giving them a negative charge which leads to repulsion between the particles. Electrostatic forces are developed causing disintegration and the free water become available for workability. 2. Lubrication: As these agents are organic by nature, thus they lubricate the mix reducing the friction and increasing the workability. 3. Retardation: A thin layer is formed over the cement particles protecting them from hydration and increasing the setting time. Most normal plasticizers give some retardation, 30–90 minutes
Super Plasticizers:
These are more recent and more effective type of water reducing admixtures also known as high range water reducer
The commonly used Super Plasticizers are as follows: Sulphonated melamine formaldehyde condensates (SMF) Give 16–25%+ water reduction. SMF gives little or no retardation, which makes them very effective at low temperatures or where early strength is most critical. However, at higher temperatures, they lose workability relatively quickly. SMF generally give a good finish and are colorless, giving no staining in white concrete. They are therefore often used where appearance is important. Sulphonated naphthalene formaldehyde condensates (SNF) Typically give 16–25%+ water reduction. They tend to increase the entrapment of larger, unstable air bubbles. This can improve cohesion but may lead to more surface defects. Retardation is more than with SMF but will still not normally exceed 90 minutes. SNF is a very cost-effective. Polycarboxylate ether super plasticizers (PCE) Typically give 20–35%+ water reduction. They are relatively expensive per liter but are very powerful so a lower dose (or more dilute solution) is normally used. In general the dosage levels are usually higher than with conventional water reducers, and the possible undesirable side effects are reduced because they do not markedly lower the surface tension of the water. Accelerators: An admixture which, when added to concrete, mortar, or grout, increases the rate of hydration of hydraulic cement, shortens the time of set in concrete, or increases the rate of hardening or strength development. Accelerating admixtures can be divided into groups based on their performance and application: 1. Set Accelerating Admixtures, Reduce the time for the mix to change from the plastic to the hardened state.
Set accelerators have relatively limited use, mainly to produce an early set. 2. Hardening Accelerators, Which increase the strength at 24 hours by at least 120% at 20ºC and at 5ºC by at least 130% at 48 hours. Hardening accelerators find use where early stripping of shuttering or very early access to pavements is required. They are often used in combination with a high range water reducer, especially in cold conditions. . Set Retarders: The function of retarder is to delay or extend the setting time of cement paste in concrete. These are helpful for concrete that has to be transported to long distance, and helpful in placing the concrete at high temperatures. When water is first added to cement there is a rapid initial hydration reaction, after which there is little formation of further hydrates for typically 2–3 hours. The exact time depends mainly on the cement type and the temperature. This is called the dormant period when the concrete is plastic and can be placed. At the end of the dormant period, the hydration rate increases and a lot of calcium silicate hydrate and calcium hydroxide is formed relatively quickly. This corresponds to the setting time of the concrete. Retarding admixtures delay the end of the dormant period and the start of setting and hardening. This is useful when used with plasticizers to give workability retention. Used on their own, retarders allow later vibration of the concrete to prevent the formation of cold joints between layers of concrete placed with a significant delay between them. The mechanism of set retards is based on absorption. The large admixture anions and molecules are absorbed on the surface of cement particles, which hinders further reactions between cement and water i.e. retards setting. Air Entrained Admixtures: An addition for hydraulic cement or an admixture for concrete or mortar which causes air, usually in small quantity, to be incorporated in the form of minute bubbles in the concrete or mortar during mixing, usually to increase its workability and frost resistance. Air-entraining admixtures are surfactants that change the surface tension of the water. Traditionally, they were based on fatty acid salts or vinsol resin but these have largely been
replaced by synthetic surfactants or blends of surfactants to give improved stability and void characteristics to the entrained air. Air entrainment is used to produce a number of effects in both the plastic and the hardened concrete. These include: • Resistance to freeze–thaw action in the hardened concrete. • Increased cohesion, reducing the tendency to bleed and segregation in the plastic concrete. • Compaction of low workability mixes including semi-dry concrete. • Stability of extruded concrete.
MANUFACTURING OF CEMENT Raw materials used Calcareous Argillaceous Calcareous materials used are
Cement rock Lime stone Marl Chalk Marine shell
Argillaceous materials used are
Clay shale slate blast furnace slag
Process manufacturing cement Dry process Wet process Dry process General
Adopted when the raw materials are quite hard The process is slow an the product is costly Process Lime stone and clay are ground to fine powder separately and are mixed together Water is added to make a thick paste which contains 14% of moisture The paste format are dried and off charged into a rotary kiln The product obtained often calcinations in rotary kiln The clinker I obtained as a result of incipient fusion and sintering at a temp about 1400◦c to 1500◦ c The clinker is cooled to preserve the meta stable compounds and there solid solutions Dispersion of one solid with another solid which made the clinker again heated Clinker is again cooled and grounded in tube mills where 2-3% gypsum is added The purpose of adding gypsum is to coat the cement particle by interfering the process of hydration of cement particles The flow diagram of dry process Wet process The operations are
Mixing
Burning
Grinding
Process The crushed raw materials are fed in to a ball mill and a little water is added The steel balls in the ball mill pulverized the raw material which form a slurry with water The slurry is passed through storage tanks where the proportioning of compound is adjusted to ensure desired chemical composition
The corrected slurry having moisture about 40%,is then fed into rotary kiln Where it loses moisture and form on to lumps These are finally burned at 1500◦ to 1600 ◦c It becomes clinker at this stage, the clinker is cooled and then grounded in tube mills While grinding the clinker 3% gypsum I added this is stored in silos and packed Concrete Mix Design concept Definition: Mix design can be defined as the process of selecting suitable ingredients of concrete and determining their relative proportions with the object of producing concrete of certain minimum strength and durability as economically as possible. One of the ultimate aims of studying the various properties of the materials of concrete, plastic concrete and hardened concrete is to enable a concrete technologist to design a concrete mix for a particular strength and durability. The design of concrete mix is not a simple task on account of the widely varying properties of the constituent materials, the conditions that prevail at the site of work, in particular the exposure condition, and the conditions that are demanded for a particular work for which the mix is designed. Design of concrete mix requires complete knowledge of the various properties of these constituent materials, these make the task of mix design more complex and difficult. Design of concrete mix needs not only the knowledge of material properties and properties of concrete in plastic condition; it also needs wider knowledge and experience of concreting. Even then the proportion of the materials of concrete found out at the laboratory requires modification and re adjustments to suit the field conditions. With better understanding of the properties, the concrete is becoming more and more an exact material than in the past. The structural designer specifies certain minimum strength; and the concrete technologist designs the concrete mix with the knowledge of the materials, site exposure conditions and standard of supervision available at the site of work to achieve this minimum strength and durability. Further, the site engineer is required to make the concrete at site, closely following the parameters suggested by the mix designer to achieve the minimum strength specified by the structural engineer.
In some cases the site engineer may be required to slightly modify the mix proportions given by the mix designer. He also makes cubes or cylinders sufficient in numbers and tests them to confirm the achievements with respect to the minimum specified strength. Mix designer, earlier, may have made trial cubes with representative materials to arrive at the value of standard deviation or coefficient of variation to be used in the mix design. American Concrete Institute Method of Mix Design 11.3 (ACI Concrete Mix Design) This method of proportioning was first published in 1944 by ACI committee 613. In 1954 the method was revised to include, among other modifications, the use of entrained air. In 1970, the method of ACI mix design became the responsibility of ACI committee 211. We shall now deal with the latest ACI Committee 211.1 method. It has the advantages of simplicity in that it: 1. 2. 3. 4.
Applies equally well With more or less identical procedure to rounded or angular aggregate To regular or light weight aggregates To air entrained or non-air-entrained concretes.
Manufacturing of concrete Introduction Production of concrete requires meticulous care at every stage The ingredients of good and bad concrete are same but good rules are not Observed it may become bad Manufacturing of concrete includes the following stages 1. Batching 2. Mixing 3. Transporting 4. Placing 5. Compacting 6. Curing 7. Finishing Batching The measurement of materials for making concrete is known as batching. Methods of batching Volume batching Weigh batching
Volume batching The required ingredients of conc. Are measured by volume basis o Volume batching is done by various types of gauge boxes o The gauge boxes are made with comparatively deeper with narrow surface o Some times bottomless gauge boxes are used but it should be avoided Volume batching is not a good practice because of the difficulties it offers to granular material. Some of the sand in loose condition weighs much less than the same volume of dry compacted soil. For un important concrete or any small job concrete may be batched by volume.
Weigh batching It is the correct method of measuring materials for concrete. Use of weight system in batching ,facilitates accuracy flexibility and simplicity The different types of weigh batching are there, they are used based on the different situation. In small works the weighing arrangement consist of two weighing buckets connected to the levers of spring loaded dials which indicates the load, The weighing buckets are mounted on a central spindle about which they rotate On large works the weigh bucket type of weighing equipment used ,the materials are fed from the over head storage hopper and it discharges by gravity.
Mixing Thorough mixing of materials is essential for the production of uniform concrete The mixing should ensure that the mass becomes homogeneous uniform in color and consistency.
Types of mixing
Hand mixing Machine mixing Hand mixing It is practiced for small scale un important concrete works Hand mixing should be done over a impervious concrete or brick floor sufficiently large size take one bag of cement . Spread out and measure d out fine aggregates and course aggregate in alternative layers. Pour he cement on the top of it and mix them dry by showel, turning the mixture over and over again until the uniformity of color is achieved. The uniform mixture is spread out in the thickness of about 20 cm The water is taken and sprinkled over the mixture and simultaneously turned over The operation is continued till such time a good uniform homogeneous concrete is obtained
Machine mixing Mixing of concrete almost invariably carried ot by machine ,for reinforced concrete work medium or large scale concrete works . Machine mixing is not only efficient it is also economical when quantity of concrete to be produced is large Type of mixer for mixing concrete
Batch mixer Continuous mixer
Batch mixer Batch mixer produce concrete batch by batch with time interval This is used in normal concrete work Batch mixers are two types Pan type
Drum type
Drum types are further classified into tilting ,non tilting and forced action type The capacity of batch mixer depends on the proportion of the mix For 1:2:4 ideal mixer 200 liters For 1:3:6 ideal mixer 280 liters Mixing time Concrete mixers are generally designed to run at a speed of 15 to 20 revolutions per minute For proper mixing it is seen that about 25to 30 revolutions are required in a well designed mixer It is important that a mixer should not stop in between concreting operations for this requirement concrete mixer must be kept maintained Transporting of concrete Concrete can be imported by variety of methods and equipments Methods adopted for transportation of concrete ]
Mortar pan
Crane, bucket and rope way
Truck mixers and dumpers
Belt conveyors
Chute
Skip and hoist
Transit mixer
Pump and pipe line
Helicopter
Wheel barrow
Mortar pan This case concrete is carried out in small quantities This method exposes greater surface area of concrete for drying conditions This results a geat loss of water particularly in hot weather Mortar pan must be wetted to start with and must be kept clean
Wheel barrow Used for transporting concrete in ground level. This method is employed for hauling concrete in longer distance in case of concrete road construction. If the distance is long or ground is rough it is likely that the concrete get segregated due to vibration To avoid this, wheel barrows are provided with pneumatic wheel. Crane bucket and rope way This is one of the right way for transporting concrete above the ground level Crane can handle concrete in high rise construction project and are becoming familiar sites in big cities Rope way buckets of various sizes are used Rope way method is adopted for Concrete works in valley Construction work of the pier in the river For dam construction
Truck mixer and dumpers For large concrete works particularly for concrete to be placed at ground level
These are ordinary open steel tipping lorries Dumpers having 2-3 cubic meter capacity Belt conveyors also can be used for
Chutes Provided for transporting concrete from ground to lower level The surface should have same slope not flatter than 1 vertical to 2 and a1/2 horizontal
Skip and hoist Adopted method for transporting concrete vertically for 3 to 4 floors Mortar pan with staging and human ladder is used for transporting concrete
Transit mixer This is the equipment for transporting concrete over a big distance particularky ready mix concrete They are truck mounted having a capacity of 4 to 7 m3 The speed of rotation of truck mixer is 4to16 rev/min A small concrete pump is also mounted on the truck carrying transit mixer
Pumps and pipe lines Universally accepted method Starts with the suction stroke for suck the concrete inside the pipe It has a piston which moves forward and backward to have suction and delivery of concrete
Choosing a correct pump involves
Length of horizontal pipe
Length of vertical pipe
Number of bends
Diameter of pipe line
Length of flexible hose
Change in line diameter
Slump of concrete
Placing of concrete Concrete must be placed in a systematic manner to yield optimum results Some situation where we used provide concrete Placing concrete within earth mould Placing concrete with large earth mould or timber plank form work Placing concrete in layers with in timber or steel shutter Placing concrete with in usual form work Placing concrete under water Placing concrete within earth mould Concrete is invariably as foundation bed below the walls and columns Before placing concrete
All loose earth must be removed Roots of trees must be cut If surface is dry must be made just damp If it is too wet or rain soaked the water slush must be removed
Placing concrete with large earth mould or timber plank form work For construction of road slabs,air field slabs and ground floor slabs in building conc os placed in this method
The ground surface must be free from loose earth pool of water ,grass or roots or leaves The earth must be compacted well
Poly ethylene film is used in between conc ground to avoid absorption of moisture Concrete is laid alternative layers to give enough scope for shrinkage
Placing concrete in layers with in timber or steel shutter This can be used in the following cases Dam construction Construction of concrete abutments Raft for a high rise building The thickness of layers depend on Method of compaction Size of vibrator Frequency of vibrator used It is good for laying 15 to 30 cm thick layer of concrete ,for mass concrete it may varie from 35 to 45 cm Its better to leave the top of the layer rough so that succeeding layer can have the good bond
Placing concrete with in usual form work This can be adopt for Column ,beam and floors Rules that should be followed while placing the concrete
Check the reinforcements are correctly tied and placed
Check the reinforcement is having appropriate cover
The joints between plywood’s or sheets properly plugged
Mould releasing agent should be applied
The concrete must be placed very care fully a small quantity at a time so that they will not block the entry of subsequent concrete Placing concrete under water
Concrete is often required to be placed under water or I a trench filled with slurry In such a cases use of bottom slurry buckets or termic pipes are used
In the bottom bucket concrete is taken through water in a water tight box or bucket reaching final place of deposition The bottom is made to open by some mechanism and the whole concrete is dumped slowly.
Compaction of concrete Compaction of concrete is the process adopted for expelling the entrapped air from the concrete Method for compacting concrete Hand compaction Compaction by vibrator Compaction by pressure and jolting
Compaction by spinning Hand compaction Adopted in case of unimportant concrete This can be adopted when mechanical mean cannot be used It consist of
Roding Ramming Tamping
Roding Poking the concrete with about 2m long 16 mm dia rod to poke the concrete reinforcement Ramming Should be done with care Permitted in unreinforced foundation concrete in ground floor construction Tamping The thickness of conc should be comparatively less Consist of beating the op surface by wooden cross beam The section of wooden beam is about 10x10 cm
Compaction by vibrators We can place the concrete economically when compared to hand compaction The use of vibrators may be essential for the production of good concrete Type of vibrators Internal vibrator Formwork vibrator Table vibrator
Platform vibrator Surface vibrator Vibratory rollers Compaction by pressure and jolting This is one of the effective method of compacting dry concrete Often used for compacting hollow block ,cavity blocks concrete blocks The stiff concrete is vibrated pressed and also given jolts With the combined action of the three the stiff conc gets compacted to an dense form to give good strength and volume Compaction by spinning This is one of the recent method of the compacting concrete This is adopted for fabrication of concrete pipes The plastic concrete when at every high speed get well compacted by centrifugal force Potential products such as spun pipes are compacted by spinning process Vibratory rollers One of the recent methods of compacting very lean or dry concrete The concrete compacted by rollers can be called as roller concrete Tests on concrete Concrete Slump Test This test is performed to check the consistency of freshly made concrete. The slump test is done to make sure a concrete mix is workable. The measured slump must be within a set range, or tolerance, from the target slump. Workability of concrete is mainly affected by consistency i.e. wetter mixes will be more workable than drier mixes, but concrete of the same consistency may vary in workability.
It can also be defined as the relative plasticity of freshly mixed concrete as indicative of its workability. Tools and apparatus used for slump test (equipment): 1. Standard slump cone (100 mm top diameter x 200 mm bottom diameter x 300 mm high) 2. Small scoop 3. Bullet-nosed rod (600 mm long x 16 mm diameter) 4. Rule 5. Slump plate (500 mm x 500 mm) Procedure of slump test for concrete: Clean the cone. Dampen with water and place on the slump plate. The slump plate should be clean, firm, level and non-absorbent. Collect a sample of concrete to perform the slum test . Stand firmly on the footpieces and fill 1/3 the volume of the cone with the sample. Compact the concrete by 'rodding' 25 times. Rodding means to push a steel rod in and out of the concrete to compact it into the cylinder, or slump cone. Always rod in a definite pattern, working from outside into the middle. Now fill to 2/3 and again rod 25 times, just into the top of the first layer. Fill to overflowing, rodding again this time just into the top of the second layer. Top up the cone till it overflows. Level off the surface with the steel rod using a rolling action. Clean any concrete from around the base and top of the cone, push down on the handles and step off the footpieces. Carefully lift the cone straight up making sure not to move the sample. Turn the cone upside down and place the rod across the up-turned cone. Take several measurements and report the average distance to the top of the sample.If the sample fails by being outside the tolerance (ie the slump is too high or too low), another must be taken. If this also fails the remainder of the batch should be rejected. Compression Test The compression test shows the compressive strength of hardened concrete. The compression test shows the best possible strength concrete can reach in perfect conditions.
The compression test measures concrete strength in the hardened state. Testing should always be done carefully. Wrong test results can be costly. The testing is done in a laboratory off-site. The only work done on-site is to make a concrete cylinder for the compression test. The strength is measured in Megapascals (MPa) and is commonly specified as a characteristic strength of concrete measured at 28 days after mixing. The compressive strength is a measure of the concrete’s ability to resist loads which tend to crush it. Apparatus for compression test Cylinders (100 mm diameter x 200 mm high or 150 mm diameter x 300 mm high) (The small cylinders are normally used for most testing due to their lighter weight) 1. 2. 3. 4.
Small scoop Bullet-nosed rod (600 mm x 16 mm) Steel float Steel plate
Procedure for compression test of concrete Clean the cylinder mould and coat the inside lightly with form oil, then place on a clean, level and firm surface, ie the steel plate. Collect a sample.
Fill 1/2 the volume of the mould with concrete then compact by rodding 25 times. Cylinders may also be compacted by vibrating using a vibrating table.
Fill the cone to overflowing and rod 25 times into the top of the first layer, then top up the mould till overflowing.
Level off the top with the steel float and clean any concrete from around the mould.
Cap, clearly tag the cylinder and put it in a cool dry place to set for at least 24 hours.
After the mould is removed the cylinder is sent to the laboratory where it is cured and crushed to test compressive strength
UNIT II CONSTRUCTION PRACTICES Specifications, details and sequence of activities and construction co-ordination – Site Clearance – Marking – Earthwork - masonry – stone masonry – Bond in masonry - concrete hollow block masonry – flooring – damp proof courses – construction joints – movement and expansion joints – pre cast pavements – Building foundations – basements – temporary shed – centering and shuttering – slip forms – scaffoldings – de-shuttering forms – Fabrication and erection of steel trusses – frames – braced domes – laying brick –– weather and water proof – roof finishes – acoustic and fire protection.
Sequence of activities and construction co-ordination Planning Planning is considered as a precondition measures before attending any development program
Particularly planning is more important in the following area When the fund available are limited The total requirement is much higher Sequence of operation It is always desirable to divide large projects into several construction stages For prepare progress of construction each stage may be constructed under separate contraction It should be carried out in the proper method and arrangement Before starting to construct the structure we must go for the sequence of operation in the project it is better way o arrange the labour material and equipment
Following are the sequence of operation in a highway project
Site clearance Earth work for laying embankment Construction of drainage works Construction of pavement structures Installation of light poles and road signals MARKING, SETTING OUT OF FOUNDATION Setting out is the process of laying down the excavation lines and centre lines on the ground before excavation is started after the foundation design is done For setting out the foundation of a small building the centre line of the longest outer wall of the building is first marked on the ground by stretching a string between wooden or mild steel pegs driven at the ends Two pegs one on either from the central peg are driven at the each end of the line Each peg is equidistant from the central peg and the distance between the outer pegs corresponds to the width of foundation trench to be excavated Each peg may be projected about 25 to 50 mm above ground level may be driven at a distance of 2m from the edge of excavation When the string is stretched joining the corresponding pegs at the two extremities of the line the boundary of the trench to be excavated can be marked on the ground with dry lime powders A right angle can be set out b forming 3, 4 and 5 units long The centre line of the other wall which is perpendicular to the long wall can be marked by setting out right angles All the specifications are made by tape or prismatic compass may be used for setting out right angles Similarly outer lines of the foundation trench of each cross wall can be set out
For big project reference pillars of masonry is constructed first, these pillars may be about 20cm thick and 15cm wider than the width of the foundation
EXCAVATION Excavation of foundation can be done by manually or with the help of special mechanical equipments Manually it can be done by the help of following equipments
Spade Phawrah Pick axe Crowbar Rammer Wedge Boning rod Sledge hammer Basket Iron pan line and pins
Mechanically the excavation can be done by the help of following machineries o o o o o
Boom bucket dipper handle Trench Chain mounted buckets Raking cut Vertical cut FOUNDATION
The foundation is he lower portion of the building, usually located below the ground level, which transmit the load of super structure to sub soil Functions of foundation
Reduction of load intensity
Even distribution of load
Provision of level surface
Lateral stability
Safety against undermining
Protection against soil movements
Types of foundation Shallow foundation Deep foundation Shallow foundation If the depth of foundation is less than or equal to width of foundation it is called as shallow foundation Types of shallow foundation Spread footing Combined footing Strap footing Mat foundation Spread footing Spread footing is those which spread the super imposed load to of a wall or column over the large area Spread footing support either a column or a wall It has the following types Single footing Stepped footing Sloped footing
Wall footing with out step Stepped footing for wall Grillage foundation Combined footing A spread footing which supports two are more columnsis termed as combined footing It has the following types Rectangular combined footing Trapezoidal combined footing Combined column wall footing Trapezoidal footing If the independent footings of two columns are connected by a beam it is called as strap footing A strap footing may be used where the distance between the columns is so great that a combined trapezoidal footing becomes quite narrow The strap beam does not remains in contact with soil and thus does not transfer any pressure to the soil Mat foundation A raft or mat is a combined footing that covers the entire beneath a structure And supports all walls and columns It is used when the allowable soil pressure is low are the building loads are heavy It is used to reduce the settlement above highly compressible soil Rafts may divided into three types o Solid slab system o Beam slab system o Cellular system Deep foundation
If the depth of foundation is equal to or more than the width of the foundation is called deep foundation Types Deep strip rectangular or square footing Pile foundation Pier foundation or drilled caisson foundation Well foundation or caissons Deep strip footing Whenever the depth of strip footing is more than the width it is called as deep strip footing Pile foundation it is a type of deep foundation in which the loads are taken to a low level by means of vertical members which may be timber or concrete or steel Types of pile foundation End bearing pile Friction pile Combined end bearing and friction pile Compaction pile End bearing piles End bearing piles are used to transfer load through water or soft soil to a suitable bearing stratum Such piles are used to carry heavy loads to hard strata Multi storied buildings are invariably founded on end bearing piles, so that the settlements are minimized Friction piles Friction piles are used to transfer loads to a depth of a friction load carrying material by means of skin friction along the length of the pile
These piles mostly used in granular soil Combined end bearing and friction pile These are the piles which transfer the super imposed load both through side friction as well as end bearing Such piles are more common, especially the end bearing piles are passed through granular soil Compaction piles These piles are used o compact loose soil thus increasing there bearing capacity The pile tube driven to compact the soil is gradually taken out and sand is filled in its place thus forming the sand pile Pier foundation A pier foundation consist of a cylindrical column of large diameter to support transfer large super imposed loads to the firm strata below Generally pier foundation is shallower in depth than the pile foundation It has two types o Masonry o concrete pier Drilled caissons Well foundation or caissons are box like structures –circular or rectangular which are sunk from the surface of either land or water to the desired depth Caisson foundations are used for major foundation work such as Bridge pier and abutments in river Wharves and quay walls docks Large water front structures such as pump houses, subjected to heavy vertical and horizontal loads Well foundations are caissons are hollow from inside, which may filled withstand and are plugged at the bottom, the load is transferred to the perimeter wall called as steining
Stone Masonry Definition: The art of building a structure in stone with any suitable masonry is called stone masonry. Types of Stone Masonry: Stone masonry may be broadly classified into the following two types: 1. Rubble Masonry 2. Ashlar Masonry 1. Rubble Masonry: The stone masonry in which either undressed or roughly dressed stone are laid in a suitable mortar is called rubble masonry. In this masonry the joints are not of uniform thickness. Rubble masonry is further sub-divided into the following three types: Random rubble masonry Squared rubble masonry Dry rubble masonry 1. Random rubble masonry: The rubble masonry in which either undressed or hammer dressed stones are used is called random rubble masonry. Further random rubble masonry is also divided into the following three types:
a. Un coursed random rubble masonry: The random rubble masonry in which stones are laid without forming courses is known as un coursed random rubble masonry. This is the roughest and cheapest type of masonry and is of varying appearance. The stones used in this masonry are of different sizes and shapes. before lying, all projecting corners of stones are slightly knocked off. Vertical joints are not plumbed, joints are filled and flushed. Large stones are used at corners and at jambs to increase their strength. Once "through stone" is used for every square meter of the face area for joining faces and backing.
Suitability: Used for construction of walls of low height in case of ordinary buildings.
b. Coursed random rubble masonry: The random rubble masonry in which stones are laid in layers of equal height is called random rubble masonry. In this masonry, the stones are laid in somewhat level courses. Headers of one coursed height are placed at certain intervals. The stones are hammer dressed. Suitability: Used for construction of residential buildings, go downs, boundary walls etc. Squared rubble masonry:The rubble masonry in which the face stones are squared on all joints and beds by hammer dressing or chisel dressing before their actual laying, is called squared rubble masonry.
There are two types of squared rubble masonry. c. Coursed Square rubble masonry: The square rubble masonry in which chisel dressed stones laid in courses is called coarse square rubble masonry. This is a superior variety of rubble masonry. It consists of stones, which are squared on all joints and laid in courses. The stones are to be laid in courses of equal layers. and the joints should also be uniform. Suitability: Used for construction of public buildings, hospitals, schools, markets, modern residential buildings etc and in hilly areas where good quality of stone is easily available. d. Un coursed square rubble masonry: The squared rubble in masonry which hammer dressed stones are laid without making courses is called un coursed square rubble masonry. It consists of stones which are squared on all joints and beds by hammer dressing. All the stones to be laid are of different sizes. Suitability: Used for construction of ordinary buildings in hilly areas where a good variety of stones are cheaply available.
2. Dry rubble masonry: The rubble masonry in which stones are laid without using any mortar is called dry rubble masonry or sometimes shortly as "dry stones". It is an ordinary masonry and is recommended for constructing walls of height not more than 6m. In case the height is more, three adjacent courses are laid in squared rubble masonry mortar at 3m intervals. 2. Ashlar masonry: The stone masonry in which finely dressed stones are laid in cement or lime mortar is known as ashlars masonry. In this masonry are the courses are of uniform height, all the joints are regular, thin and have uniform thickness. This type of masonry is much costly as it requires dressing of stones.
Suitability: This masonry is used for heavy structures, architectural buildings, high piers and abutments of bridges. Ashlars masonry is further sub divided into the following types:
Ashlars fine or coarse ashlar masonry Random coarse ashlars masonry Rough tooled ashlar masonry Rock or quarry faced ashlars masonry Chamfered ashlars masonry Block in coarse masonry Ashlar facing Ashlar fine or coursed ashlar masonry: In this type of stone masonry stone blocks of same height in each course are used. Every stone is fine tooled on all sides. Thickness of mortar is uniform through out. It is an expensive type of stone masonry as it requires heavy labor and wastage of material while dressing. Satisfactory bond can be obtained in this type of stone masonry. Random coursed ashlar masonry: This type of ashlar masonry consists of fine or coursed ashlar but the courses are of varying thick nesses, depending upon the character of the building Rough tooled ashlar masonry: This type of ashlar masonry the sides of the stones are rough tooled and dressed with chisels. Thickness of joints is uniform, which does not exceed 6mm. Rock or quarry faced ashlar masonry: This type of ashlar masonry is similar to rough tooled type except that there is chisel-drafted margin left rough on the face which is known as quarry faced. Chamfered ashlar masonry: It is similar to quarry faced except that the edges are beveled or chamfered to 450 for depth of 2.5 cm or more. Block-in course masonry: It is the name given to a class of ashlar masonry which occupies an intermediate place between rubble and ashlars. The stones are all squared and properly dressed. It resembles to coursed rubble masonry or rough tooled ashlar masonry.
Ashlar facing: Ashlar facing is the best type of ashlars masonry. Since this is type of masonry is very expensive, it is not commonly used throughout the whole thickness of the wall, except in works of great importance and strength. For economy the facing are built in ashlars and the rest in rubble. Brick masonry
cher bricks on edges instead of bed
This bond is weak in strength but it is economical Brick masonry is made up of brick units bonded together with mortar Components of brick masonry Brick Mortar Types of mortar
Cement mortar Lime mortar Cement-lime mortar Lime surkhi mortar Mud mortar
Types of bricks Traditional bricks Modular bricks Traditional bricks It has not been standardize in size Dimensions varies from place to place Thickness varies from varies from cm to 7.5cm,widthvaries from 10to13 cm and length varies from 20to25 cm Modular brick Any brick which is the same uniform size as laid down by bis The nominal size of the modular brick is 20cm x10cmx10cm Actual size is 19x9x9 Classes of brick First class brick Second class brick Third class brick
Bonds in brick work Stretcher bond Header bond
English bond Flemish bond Facing bond English crossing bond Brick on edge bond Dutch bond Racking bond Zigzag bond Garden wall bond
Stretcher bond The length of the brick its along with the face of the wall\ This pattern is used only for those wall which have thickness of half brick Header bond The width of the bricks are thus along the direction of the wall This pattern is used only when the thickness of the wall is equal to one brick English bond It is the most commonly used methodthis bond is considered to be the strongest This bond consist of alternate course of stretchers and headers Alternative courses will show either headers or stretchers in elevation There is nop vertical joint Every alternative header come centrally over the joint between two stretchers in corse in below Since the number of vertical joint in the header course twice the number of vertical joints in stretcher course ,the joints in the header course are made thinner than the joints in the stretcher course Flemish bond Inthis type of course is comprised of alternative headers and stretchers Types of Flemish bond Double Flemish bond
Single Flemish bond Double Flemish bond Every course consist of headers and stretchers placed alternatively The facing and backing of the wall in each course have the same appearance Single Flemish bond Single Flemish bond is comprised of double Flemish bond facing an English bond backing and hearting in each course
Facing bond This bond is used where the bricks of different thickness are to be used in the facing and backing of the wall The nominal thickness of facing brick is 10 cm and that of backing bricks is 9 cm the header course tis provided at a vertical interval of 90 cm English cross bond This is he modification of English bond to improve the appearance e of the wall Brick on edge bond This type of bond uses stret dutch bond
DAMP PROOF COURSE Materials for Damp Proof Course (DPC): An effective damp proofing material should have the following properties; 1. It should be impervious. 2. It should be strong and durable, and should be capable of withstanding both dead as well as live loads without damage. 3. It should be dimensionally stable. 4. It should be free from deliquescent salts like sulphates, chlorides and nitrates.
The materials commonly used to check dampness can be divided into the following three categories: 1. Flexible Materials: Materials like bitumen felts (which may be hessian based or fibre/glass fibre based), plastic sheeting (polythene sheets) etc. 2. Semi-rigid Materials: Materials like mastic, asphalt, or combination of materials or layers. 3. Rigid Materials: Materials like first class bricks, stones, slate, cement concrete etc. SELECTION OF MATERIALS FOR DAMP PROOF COURSE: The choice of material to function as an effective damp proof course requires a judicious selection. It depends upon the climate and atmospheric conditions, nature of structure and the situation where DPC is to be provided. The points to be kept in view while making selection of DPC materials are briefly discussed below: 1. DPC above ground level: For DPC above ground level with wall thickness generally not exceeding 40cm, any one of the type of materials mentioned above may be used. Cement concrete is however commonly adopted material for DPC at plinth level, 38 to 50mm thick layer of cement concrete M15 (1:2:4 mix) serves the purpose under normal conditions. In case of damp and humid atmosphere, richer mix of concrete should be used. The concrete is further made dense by adding water proofing materials like Pudlo, Impermo, Waterlock etc in its ingredients during the process of mixing. It is used to apply two coats of hot bitumen over the third surface of the concrete DPC. 1. DPC Material for floors, roofs etc: For greater wall thickness or where DPC is to be laid over large areas such as floors, roofs, etc, the choice is limited to flexible materials which provide lesser number of joints like mastic, asphalt, bitumen felts, plastic sheets etc. The felts when used should be properly bonded to the surface with bitumen and laid with joints properly lapped and sealed. 1. DPC Material for situations where differential thermal movements occur: In parapet walls and other such situations, materials like mastic, asphalt, bitumen felts and metal (copper or lead) are recommended. It is important to ensure that the DPC material is flexible so as to avoid any damage or puncture of the material due to differential thermal movement between the material of the roof and the parapet. 2. DPC material for Cavity Walls: In cavity wall construction, like cavity over the door or window should be bridged by flexible material like bitumen felt, strips or lead etc. General principles to be observed while laying DPC are:
1. The DPC should cover full thickness of walls excluding rendering. 2. The mortar bed upon which the DPC is to be laid should be made level, even and free from projections. Uneven base is likely to cause damage to DPC. 3. When a horizontal DPC is to be continued up a vertical face a cement concrete fillet 75mm in radius should be provided at the junction prior to the treatment. 4. Each DPC should be placed in correct relation to other DPC so as to ensure complete and continuous barrier to the passage of water from floors, walls or roof. Figures 1 to 7 explain provision of DPC under different conditions
Figure 1: Air Drain
Figure 2: DPC Treatment for basement on undrained soils.
Figure 3: Plan of building showing DPC
Figure 5: Asphalt tanking for basement
Figure 6: DPC for flooring
FLOORS The purpose of floor is to provide a level surface capable of supporting the occupants of the building, furniture, equipment and some time interior wall The floor must satisfy the following requirements Adequate strength and stability Adequate fire resistance Sound proof Damp resistance Thermal insulations
Components of a floor Sub floor, basecourse or floor base Floor covering or flooring Selection of flooring materials
Factor that affect the choice of flooring
Initial cost Appearance Cleanliness Durability Damp resistance Sound insulation Thermal insulation Fire resistance Smoothness Hardness Maintenance
Types of flooring
Mud flooring and muram flooring Brick flooring Flag stone flooring cement concrete flooring Terrazzo flooring Mosaic flooring Tiled flooring Marble flooring timber flooring Asphalt flooring Rubber flooring Linoleum flooring Cork flooring Glass flooring Plastic or pvc flooring
Mud flooring and muram flooring This type of flooring is cheap, hard highly impervious It is easy to construct and easy to maintain It has good thermal insulation property due to which it remains cool in summer and warm in winter Over a well prepared ground 25 cm thick selected moist earth is spread and it rammed well to compacted thickness of 15cm In order to prevent cracks small quantity of chopped straw is mixed
Muram flooring Muram is a form of disintegrated rock with binding material To construct such a floor a 15 cm thick layer muram is laid over prepared sub grade over it 2.5 cm thick powder layer of muram is spread and rammed
Brick flooring The sub grade is compacted properly, to the desired leveland 7.5 cm thick layer is spread Over this a course of brick is laid flat in mortar is built Such flooring is used in cheap construction, especially where good bricks are available Flag stone flooring Flag stone is laminated sand stone available in 2cm to 4cm thickness in the form of stone slab of 30X30 cm or 45X45cm and 60X60 cm This type of works also called paving. The stones are laid on concrete base the subsoil is properly compacted over which 10 to of lime concrete or lean cement concrete is laid Cement concrete flooring This is commonly used for residential, commercial even industrial building.. It is moderately cheap quite durable and easy to construct The floor consist of two components Base concrete Topping or wearing surface
The base course ma be 7.5 to 10 cm thick The topping consist of 1:2:4 cement concrete Terrazzo flooring
Terrazzo flooring is another type of floor finish that is laid in thin layer over concrete topping It is very decorative and good wearing properties Terrazzo is a specially prepare concrete surface containing cement and marble chips in the proportion to 1:1 1/4 to 1:2 When the surface has set the chips are exposed by grinding operation
Mosaic flooring Mosaic flooring Is made of small pieces of broken tiles of china glazed or of cement or of marble arranged in different pattern These pieces are cut to desired shape and sizes a concrete base is prepare as in the case of concrete flooring over that 5to8 thick lime surkhi mortar is spread over an area, over this 3mm thick cementing paste is layered and is left to dry about 4 hours, ,there after small pieces of broken tiles or marble pieces of different colors arranged definite pattern and hammered in different layers Tiled flooring Tiledflooring is constructed from square ,hexagonal or other shapes made up of clay cement concrete and terrazzo These are available In various thickness Thes are commonly used in residential houses ,schools,hospitals and other public buildings Over the concrete base a 25 to 30 mm thick layr of lime mortar 1:3 to serve as a bedding The bedding mortar is allowed to harden for 12 to 24 hours Neat cement slurry is spread over it and the tiles are laid flat over it
Marble flooring It is the superior type of flooring used in bathrooms and kitchens of residential building and hospitals ,sanitorium ,temples etc After the preparation of base concrete 20 mm thick bed layer of 1:4 cement mix spread under the area of each individual slabs.
The marble layer is then laid over it and pressed with wooden mallet and leveled Timber flooring Timber flooring is used for carpentry halls ,dancing halls auditorium Etc These are not commonly usedin India because its costlier But hilly area where wood is available and temperature drops very low timber flooring is quite common The suspended type of wooden floor is supported above the ground The solid type of wooden floor is fully supported on the ground
SCAFFOLDING When te higt of wall or column or othet structural member of a building exceeding1.5 m temporary structures needed to support trhe platforms over which the work man sit and carry o the work These temporary structures constructed very close to the wall is in the form of imber o steel frame work commonly called as scaffoldings Components of scaffoldings Ledgers Braces Put logs Transoms Boarding Guard rail Toe board
Single scaffolding or brick layer scaffolding Double scaffoldings or masons scaffoldings Cantilever or needle scaffoldings Suspended scaffoldings Trestle scaffolding Steel scaffolding Patented scaffoldings
Single scaffoldings This consists of a single frame work of standards, legers, put logs etc
Constructed parallel to the wall at a distance of about 1.2 meters The standards are placed at a distance of 2to2.5m interval Ledger connected with the standards, and are provided at a vertical distance of 1.2to 1.5 m Put logs or connected with one end on the ledgers and other end at the holes of the wall at an interval of1.2 to 1.5 m interval Double are masons scaffoldings
It is very difficult to put holes in walls to m support putlogs in stone masonry In the case a strong scaffolding is used consisting of two rows of scaffolding The first row placed 20 to 30 cm away from the wall the other frame will 1m distance from the first one Put logs are the supported on both the supports, rakers and cross braces are provided to make the scaffolding more strong It also called as independent scaffoldings
Cantilever or needle scaffolding Cantilever supports can be used under following circumctances Ground is week to support standards Construction of the upper part of the wall is to be carried out It is required to keep the ground near wall free for traffic etc i It ha s two types Single Frame Te standards are supported on series of needle taken out through opening or through holes Double frame The needles are projecting beams are strutted inside the floors Suspended scaffolding It is the light weight scaffolding used for repair works such as pointing, painting etc The working platforms are suspended from roofs by means of wire ropes or chains etc
Trestle scaffolding Such type of scaffoldings are used for painting and repairing work inside the room up to a height of 5m The working platform is supported over the top of movable contrivances such as tripods ladders etc Steel scaffolding Steel scaffolding is practically similar to the timber scaffolding, here wooden members are replaced by steel couplets are fittings Such scaffolding can be erected and dismantled rapidly It has a greater strength and greater durability Patented scaffolding Many patented scaffolding made of steel are available in the market Thos scaffoldings are equipped with special couplings frames etc TRUSSES
Trusses are the frame formed by number of straight members connected in the form of triangles The embers are made by steel angles and they are joined by rivet or welding, these joints are called nodes It is assumed that the external loads act at the nodes only and the members are subjected to only tension or compression The compression members are called as struts and the tension members are called as ties Steel roof trusses are used under the following condition Large spans are to be covered Intermediate columns are to be avoided to have an unobstructed working area inside There is a heavy rain or snow fall
Types of roof trusses
King post truss
Here t he common rafters are supported by wooden frame work called truss under required interval The frame work consist of a king post, two struts two principal rafters and tie beam The truss rest on stone bed blocks at either end The common rafters rest on wooden purlins which in turn are fixed to the principal rafters of the truss The king post connect the ridge post and the middle of the tie beam The struts are connected to the king post at the bottom and the principal rafters at the top The roofing material is fixed to the common rafters king post truss is used for spans of 5m to 9m Queen post truss
The frame work consist of two principal rafters ,two queen post one straining sill two struts one tie beam and one straining beam The common matters rest on wooden purlins The staining beam resist the horizontal thrust developed The struts are connected to the queen post at the bottom and the principal rafters at the top North light roof truss
North light or saw tooth roof truss is special type of roof trusses suitable for factories engaging in manufacturing work North light truss is sawtooth Actual lighting is taken an advantage during day time by using the north light roof trusses In this type of trusses vertical drops are provided this drops are covered with glasses so as to permit light in to the interior
Centering and shuttering
Shuttering is the temporary ancillary construction used as a mould for the structures In which the concrete is placed and allowed to hardened These are classified as steel wooden plywood combined woods steel, reinforced concrete and plain concrete Requirements of shuttering The material should be cheap and should be suitable for re use several times
It should be practically water proof so that it should not observe water from concrete It should be strong enough to with stand all loads coming on it It should be stiff enough so that deflection is minimum
The surface of the formwork should smooth and it should afford easy stripping Loads on form work Live load due to labour etc Dead weight of wet concrete Hydrostatic pressure of the fluid concrete Impact due t pouring concrete Shuttering for column Components Sheeting or column shutter all around the column Yokes Wedges bolt
Shuttering for beam and slab floor The slab is continous over the beam The slab is supported on 2.5 cm thick sheeting laid parallel to the main beam
form work for stairs Shuttering of walls The boarding may be 4 to 5 cm thick for walls up to 3to 4m high The boards are fixed to 5cmX10cm posts known as struts are soldiers
ROOF FINISHING Roof finishing accessories include all types of accessory materials that are used to finish a roof. Flashing, drip edge, and roof drains are all examples of roofing accessories. Roof finishing accessories are widely available for a range of applications and may be chosen for functional, aesthetic, or budgetary reasons. Roofing accessories are largely made from aluminum, steel, copper, or PVC vinyl. They include a range of products including Rain gutters and Drains and guards Flashing or weatherproofing materials
Roof caps
Drip edges
Ridges and shingles
Chimney caps
Leader boxes
Finials and turrets
Weathervanes.
Rain gutters and Drains and guards Rain gutters, drains and guards are roof finishing accessories that collect and divert rainwater away from the roof and building foundation. These types of roof finishing accessories may also reduce erosion, prevent leaks in the foundation or basement, reduce water exposure on painted surfaces, and collect water for additional use. Rain gutter, drain and guard roof finishing accessories may be available with screens, louvers, or hoods for additional protection. Flashing or weatherproofing materials Roof finishing accessories also include flashing, also known as weatherproofing. Flashing refers to installing a thin, continuous piece of sheet material to prevent the passage of water into the structure from a joint or angle. Flashing roof finishing accessories are commonly used around protruding objects in the roof, such as chimneys or pipes, to prevent water from reaching seams or joints.
Roof caps, drip edges, ridges and shingles, and chimney caps
Roof caps, drip edges, ridges and shingles, and chimney caps are also common, functional roof finishing accessories . Roof caps provide ventilation via the rooftop. They are commonly made from copper or galvanized steel, and often include an insect screen. Drip edge roof finishing accessories are useful in stopping water from seeping under a roof deck, which can prevent frame rot. Roof ridge caps and shingles are also used as finishing accessories. Roof shingles are individual, overlapping elements used for water-resistance. At the roof ridge, there is typically a copper, lead, or plastic cap to ensure water protection. Ridge vents are also commonly used as roof finishing accessories to provide ventilation to attic or upper crawlspaces.
Leader boxes, Finials and turrets and Weathervanes. Finishing accessories can also be decorative. These accessories include leader boxes, finials and turrets, and weathervanes. Leader box accessories are used with gutter systems to hide or diminish the sight of leader elbows, and are available in a range of decorative styles, shapes, and designs.
Roof finials and turrets are caps or towers affixed to the highest point of the roof, largely for decoration. Turrets are often designed to hold clocks or bells. Similarly, weathervanes are another type of roof finishing accessory often used for decoration at the highest point of the roof. Weathervanes are not solely used for decoration, however, as they also point to the direction of the wind. Other, unlisted types of roof finishing accessories may also be available.
ACOUSTICS
Acoustics is the science of sound ,which deals with origin ,propagation and auditory sensation of sound and also with design and construction of different building units to set optimum condition for producing and listenig speech musi etc FIRE PROTECION No building material is perfectly fire proof A wider interpretation of the fire safety may be deemed to cover the following aspects Fire prevention and reduction of number of out breaks of fire Spread of fire both internally and externally Safe existence of any and all occupants in the event of an out breaks of fire Fire load Fire load is the amount of heat in kilocalories which is liberated per square meter of floor area of any combustible parts of the building itself The fire load is determined by multiplying the weight of all combustible materials by their calorific value and dividing the floor area under consideration Grading of building according to fire resistance The national building code of India (sp:7-1970) divides building in to the following four types according to the fire load the building is designed to resist Type 1 construction all structural components have 4 hours fire resistance Type 2 construction all structural components have 3 fire resistance Type 3construction all structural components have 2 hours fire resistance Type 4 construction all structural components have 1 hour fire resistance General fire safety requirements for buildings
All building and particularly building having more than one storey shall be provided with liberally designed and safe fire proof existence The exist shall be so placed that they are always immediately accessible and each is capable of taking all the persons on that floor a s alternative escape route Escape route shall be well ventilated as persons using the escapes are likely to over come from smoke Fire proof door shall conform rigidly to the fire safety requirements Electrical and mechanical lifts while reliable undr normal condition may not always be relied on escape purpose Lift shafts and stairways invariably serve as flues are tunnels thus increasing the fire by increased draught Floors are required to withstand the effect of fire for full period stated for the particular grading Roofs of the various fire grades of the building shall be designed and constructed to withstand the effect of fire for the maximum period
UNIT III SUB STRUCTURE CONSTRUCTION Techniques of Box jacking – Pipe Jacking -under water construction of diaphragm walls and basement-Tunneling techniques – Piling techniques - well and caisson - sinking cofferdam – cable anchoring and grouting-driving diaphragm walls, sheet piles - shoring for deep cutting – well points -Dewatering and stand by Plant equipment for underground open excavation.
TECHNIQUES OF BOX JACKING Necessity of this technique When the increasing demands for various forms of transport infra structure to be constructed in congested locations or below existing facilities the need to be able to install large structures without destruction is a growing need. The jacking of large boxes to create an underpass below a railway track or road without destruction For around 30 years this box jacking techniques has found wide use Europe and India Types of structures under jacking Box jacking Arch jacking Pipe jacking OPERATONS The box shaped tunnel structures are pre fabricated units which are pushed into soil by hydraulic jack Soil is excavated at the advancing face by manual means or by excavators To avoid settlements of over laying roads or rail track soil is excavated after it enters the cutting heads Excavation ahead of the cutting is avoided the cutting head is moved forward in small increments to avoid any having of the road or rail track In addition to that, without stabilizing the soil, the box technique would cause the super structure to settle the threatening structure failure so the ground ahead of tunnel boxes needed to be frozen
PIPE JACKING In tunnels of damages above 2m men and machines worked the tunnel phase exacting and providing soil support to the excavator soil by erecting the lining. The tunnel diameter becomes small it becomes difficult for workers to carry out soil excavation of in erect the tunnel lining system with in the tunnel shield For diameter in the range of 0.5m to 1.5m it is more efficient to excavate the soil by drilling systems controlled from a shaft or a pit to push the tunnel lining segment from the shaft or pit these techniques are often referred to us pipe jacking or micro tunneling techniques and equipments Pipe jacking refers to a technique in which a man in a sitting or crouch position, user’s epic and shovels to excavate tunnel face and the pipe is jacked forward from a shaft using hydraulic jacking system Horizontal auguring refers to a similar technique in which the man is replaced by a horizontal continuous flight helical auger INSTALATION The pipe sections are moved forward by hydraulic jacking and the miniature TBM derive its reaction from these section Pipe segments of length 1 to 3 diameters 0.5 to 2m can be jacked into the soil using reaction from the concrete wall erected at the rior of jacking pit.
DIAPHRAGM WALL In structural engineering, a diaphragm is a structural system used to transfer lateral loads to shear walls or frames primarily through in-plane shear stress . These lateral loads are usually wind and earthquake loads, but other lateral loads such as lateral earth pressure or hydrostatic pressure can also be resisted by diaphragm action. The diaphragm of a structure often does double duty as the floor system or roof system in a building or the deck of abridge, which simultaneously supports gravity loads. Diaphragms are usually constructed of plywood or oriented stand board in timber construction; Metal deck or composite metal deck in steel construction; or concrete slab in concrete construction.
The two primary types of diaphragm are flexible and rigid. Flexible diaphragms resist lateral forces depending on the tributary area, irrespective of the flexibility of the members that they are transferring force to . On the other hand, rigid diaphragms transfer load to frames or shear walls depending on their flexibility and their location in the structure. Parts of a diaphragm include:
the membrane, used as a shear panel to carry in-plane shear the drag strut member, used to transfer the load to the shear walls or frames The chord, used to resist the tension and compression forces that develop in the diaphragm, since the membrane is usually incapable of handling these loads alone.
TUNNELING Process of making tunnels in order to reduce distance of travel or traffic congestion for highway and railway is called tunneling Tunneling is important for the following purpose o o o o o o o o o o
Time saving and reduction in fuel Avoid unwanted traffic congestion Maintain a proper speed Avoid tiredness of travel Avoid unwanted accidents To avoid deforestation and death of animal while crossing To avoid land slide in hilly region To avoid the long route around the mountain To reduce the length of highway and railway and it may be economical To have flatter gradient that is essential to maintain the speed of the vehicle
Tunneling types depending upon the shapes Poly centric Horse shoe Size of the tunnel It depends upon the number of track and the width and length of the mountain Alignment of tunneling
o o o o o
Identify the shortest route Height of mountain should be less Mark the points on the mountain Transfer the tunnel inside the mountain by making of required depth Checking the tunnel cross section whether equal every where
Methods of tunneling Shaft tunneling Pilot tunneling Shaft tunnels Vertical passages are created along the line o the tunnel then the tunnels can be excavated by the passage of having distance half of the distance between adjacent passage openings are available to take the excavated material ,shafts can also be used to pump out the water Pilot tunneling If the height of the mountain is more then we can exercise this method of tunneling but uf he horizontal length is more, shaft tunneling is done PILE DRIVING This is the process of inserting the pile inside the soil It is a process by way of which a pile is forced in to the ground with out excavating the soil Pile driving an be done by two methods Using hammering Using pile driver Hammering Heavy bl0w is given by means of a hammer Variety of hammers available to perform some of the acion
Drop hammer Single acting hammer Double acting hammer Diesel hammer and Vibrating hammer
Drop hammer The hammer is lifted by a winch and dropped down The hammer is connected to the rope by a hook When it is lifted up after reaching a particular height it is dropped down Single acting hammer Hammer is lifted by stream and dropped then it will fell down in the top of the pile by gravitational force Double acting hammer It is the same as that of single acting but here both the lifting and dropping is done by steam engine Diesel hammer The process of lifting and dropping is done by diesel engine Vibrators If the soil condition is loose ,then using some vibrators the pile is inserted
SHEET PILES It is the type of pile that is made of concrete, steel or wood The thickness of the pile is very less when compared to the length and width of the pile To prevent the entry water in construction the sheet piles are used, this is also used to separate the vertical member of the building The piles are inserted by some machine the depth of the piles can be increased by proper joints in successive installment
Functions To enclose the site or part to prevent escape of loose soil
To retain the sides of trenches or excavation To construct retaining wall in the marine structures To prevent seepage below the dams or hydraulic structures to construct coastal defense work To protect the foundation from scouring action of nearby river
Concrete sheet piles Reinforced precast unit having the width of 50 to 60 cm and thickness 2to 6cm and the depth can be increased by further installment Timber sheet piles it is used only for temporary works ,the width of the pile varies from 225to 280 cm the thickness shall not be less than 50mm
DEWATERING DEFINITION When water table exists at a shallow depth below ground surface, it is essential to lower the water so as to carry out construction of foundation, basement, and metro tunnels etc.This is achieved by pumping out water from multiple wells installed at the site. The process is called as dewatering. Types of dewatering method Dewatering can be done by adopting one of the following four strategies Dewatering of soil by temporary lowering of water table using wells and pumps prior excavation as depleted in figure Allowing water to reap into excavation area, collecting it in sumps and pumping it out. Before that adequate steps have to be taken to support the soil on sides of the excavated area, to prevent washing away of fines and have sufficient space for the work area. Making the soil around excavated zone impermeable by technique such as grouting are freezing so that inflow of water is stop are minimized. INSTALATION TECHNIQUE
Sufficient size and capacity of dewatering system is necessary to lower and maintain ground water table and to allow material to be excavated in a reasonable dry condition. Excavation slopes to be stabilized where sheeting is not required Dewatering system is to be operated continuously until backfill work has been completed. Then, the structure to be constructed at the excavated area has to be finished The complete stand by have to be available for immediate operation as may be required, to adequately maintain dewatering on continuous basis and in the event that all or any other part of the system may become inadequate or fail The water removed from the excavation to be disposed in such a manner as will not endanger portions of work under construction or completed. For dewatering purpose, well points deep well, caissons and tunnels are used.
WELL POINTS DEWATERING When construction operation have to be excited below the ground water table level. Dewatering of soil can be done by the following methods Collecting water in sumps and pumping it out. Installing well points small or deep wells and pumping out ground water Using special technique in fine grained soils such as vaccum dewatering and electroosmosis WELL POINTS To pump out the ground water small sized wells called well points are used for a more dry working area the two methods used most often for lowering water table below the excavation level are the well point method and the deep well method. WELL POINT METHOD : This is economical and useful for lowering the water table by 15m or less. Incase of well point method or deep well method it is based on the fact that removal of water by continuous pumping from a well causes the water table level to become depressed and result in the formation of draw down. When a series of wells are placed close to each other, the overall effect is lowering of the water table level.
Well points, being smaller, are easy to install. Well points, can lower the water table by only 6.7m because the pump, is located at the ground surface and connected to group of well points through a pipe, cannot lift water from greater depth. Beyond 7m, multistage well points are used. DEEP WELL METHOD This method is useful for lowering the water table by more than 15m. Deep wells have larger diameter more depth and greater spacing. The pump is located at the bottom of well and hence can pump out water from greater depth. Deep wells become more economical if more points are required.
UNIT IV SUPER STRUCTURE CONSTRUCTION Launching girders, bridge decks, off shore platforms – special forms for shells - techniques for heavy decks – in-situ pre-stressing in high rise structures, Material handling - erecting light weight components on tall structures - Support structure for heavy Equipment and conveyors –Erection of articulated structures, braced domes and space decks. BRIDGE DECKS The principal function of a bridge deck is to provide support to local vertical loads (from highway traffic, railway or pedestrians) and transmit these loads to the primary superstructure of the bridge, Figure 1(1). As a result of its function, the deck will be continuous along the bridge span and (apart from some railway bridges) continuous across the span. As a result of this continuity, it will act as a plate (isotropic or orthotropic
depending on construction) to support cal patch
Continuity ensures that whether or not it has been designed to do so, it will participate in the overall structural action of the superstructure. The overall structural actions may include:
Contributing to the top flange of the longitudinal girders, Figure 1(2).
Contributing to the top flange of cross girders at supports and, where present in twin girder and cross girder structures, throughout the span, Figure 1(3).
Stabilising longitudinal and cross girders, Figure 1(4).
Acting as a diaphragm to transmit horizontal loads to supports, Figure 1(5).
Providing a means of distribution of vertical load between longitudinal girders, Figure 1(6).
It may be necessary to take account of these combined actions when verifying the design of the deck. This is most likely to be the case when there are significant stresses from the overall structural actions in the same direction as the maximum bending moments from local deck actions, e.g. in structures with cross girders where the direction of maximum moment is along the bridge. The passage of each wheel load causes a complete cycle of local bending stresses. The number of significant stress cycles is, therefore, very much higher for the deck than for the remainder of the superstructure. In addition, some of the actions of the deck arising from its participation in the overall behaviour are subject to full reversal; an example is the transverse distribution of vertical load between girders. For both these reasons, fatigue is more likely to govern the design of the bridge deck than the remainder of the superstructure. SHELL STRUCTURES Shells are 3d structures constructed on storage tanks or roof for large column area such as indoor stadiums, exhibition halls, theatres, complex churches etc Classification Singly curved Doubl curved Cylindrical shells Singly curved It can be used for rectangular shape buildings, shells represents the roof of the building Dome storage tank for water and petroleum is example for single curved Doubly curved
For doubly curved structures the super structure should be in hexagonal or circular shape Cylindrical shape These ae just modification of pitched roof and frequently emloyed in modern age construction It has two types North light shell roof Barell vault shell roof Both are different to provide lighting effect in factories In barell vault ventilation s provided in middle
Off shore platforms
Off shore platforms are self contained platforms with adequate facilities for drilling, derrick, drilling mud electric power, pumping equipment for the offshore construction these are artificial facilities above the elevation of off shore platforms Off shore platforms can be classified as Fixed Off shore platforms Bottom supported structures Compliant platforms and floating platforms Construction principles of offshore platforms Selection of operational criteria Selection of environment Environmental factors like Storming wind velocity Storming wave height Tidal conditions
Before analysis and design of foundation it is necessary to determine the soil characters of the sea shore. Capacities of the available crains will influence the operational activities of platform constructions. The fixed platforms can be classified into Jacket or template structures Gravity structures ERECTING LIGHT WEIGHT COMPONENTS ON TALL STRUCTURES Besides high raise buildings the usage of steel element is also popular with construction of hospital and commercial complexes Instead of concrete beams and columns more than 6100 tonnes of steel have been used to build the main frames Light weight blocks are used for patricians to reduce the dead load building The usage of permanent concrete form works and structural steel elements will be the main constituter for erecting light weight components on tall structures results rapid speed of constructions. Hence the erection of steel beams and columns as well as the installation of concrete form work consumes only less time Self drilling tapping screws are the most prevalent fasteners. Steel to steel connections can be carried out to connect struts or joist and track together Entire can be erected manually with out the use of heavy equipment All these structures require few battery powered screw gunes and some ropes and pulleys No scaffoldings is require for assembly and disc assembly of the structures because the structure itself provides the scaffoldings as it goes up or comes down Almost any number of column sections can be added to make it any height we desire
During the construction of tall structures the following equipments areused for the aerial transporting and handling Aerial cable way Helicopter
UNIT V CONSTRUCTION EQUIPMENT Selection of equipment for earth work - earth moving operations - types of earthwork equipment - tractors, motor graders, scrapers, front end waders, earth movers – Equipment for foundation and pile driving. Equipment for compaction, batching and mixing and concreting - Equipment for material handling and erection of structures - Equipment for dredging, trenching, tunneling,
Construction equipments
Types of earth moving equipment
Classified into following types Production equipment Equipment used for digging and moving Service equipment Dozers and motor girders
Tractors Tractors are machine which change the engine energy into tractive energy These are primarily used for pull or push the loads They are also used for different purposes by mounting many types of accessories Types of tractor Crawler type or track type Rubber tired or wheel type The tractor is multi purpose machine Light models are used for agricultural or short haulage works Heavy models are employed in earth moving works, cranes, shovels or special rigs Wheeled types or employed in light but speedy jobs Main constituents of tractor are engine ,clutch ,transmissonsystem,ground drive and controls
Factors should be considered while selecting a tractor dozer Size of the dozer for given job the type expected from the track to dozer The type and condition of haul road distance to be move Bulldozers
Dozers are machine designed primarily for cutting and pushing the material over short distance They consist with a front mounted blade controlled by hydraulic cylinder to vary the depth of cut and rate of leveling depending on the material and application a dozer is frame mounted unit with a blade, curved in its section, extending in front of the tractor Bulldozer is most versatile and most important equipment on construction project Basically its pushing unit but its widely used as multipurpose equipment and can perform large number of operations with minor changes Scrapers Scrapers are the devices to scrap the ground and load it simultaneously, transport it for the required distance and dump it and then spread it for the required area The scrapers are designed to dig,load,haul,dump and spread The scrapers are of three types towed type conventional type self loading or elevating scrapers Towed type The towed type scrapers are provided with either cable or hydraulic control It can be operated in extremely adverse condition Conventional scrapers These are generally manufactured from 10to 25cubicmetres Self loading scrapers These are twin engine scrapers It can work completely independently of all other plants It has the following parts Bowl Cutting edge Apron Tail gate or ejector
Following or three major operations of scrapers Loading or digging Transporting Unloading
SELECTION OF EQUIPMENT Proper selection of construction equipment place a vital role in the speedy and economical completion of the construction Following are the main points which should be considered while selection off the construction equipments Suitable for job condition The equipment must meet the requirement of the work climate and working condition Size of the equipment Size of the equipment it should be such that must be able to be used with other equipments If the equipment selected for larger size it will remain idle inmost of the time Standardization It is better to have same type and size of equipment in a construction then it is easy to have spare parts, and to understand its operations Availability of equipment Availability of spare parts Multi purpose equipments the selected equipments must be capable of performing various operations Availability of know how The equipments selected should be satisfactorily handled by the available operators and machine Use in future projects The economical aspects Reliability of the equipments
Service support Operating requirements Past performance Reputation of the manufacturer Warranty and guaranty offered by the manufacturer Adequacy of drive mechanism EXCAVATORS Excavators are basically digging machines having three major components An under carriage to give mobility A super structure with operators cabin mounted on either a sloe ring to traverse through 360◦or on a rigid frame Hydraulically articulated boom or tipper arms with bucket Types of excavators Crawler mounted excavators Truck mounted excavators Self propelled excavators Excavators mounted on barge or rail Compactors Compaction is the process where by material particles are constrained to pack more closely together througha reduction of air void content generally by mechanical means Types of compactors static smooth wheeled rollers sheep foot and pad foot rollers pneumatic tired rollers
vibratory rollers Static compaction equipment It has several types towed static smooth compactors static sheep foot or pad foot compactors static three wheel self propelled compactors static tandem compactors three axle static compactors Towed static smooth compactors Smooth rolls where the first type of rolling compaction equipment used These where pulled by men or horses and were first used by Romans to smoothen there roads Static sheep foot or pad foot compactors When compacting the earth the feet penetrate deep in to th e loose material during the first passes and compact the soil from bottom up The kneading effect of sheep foot compactors is used to break up the Earth lumps and reduce the air voids Static three wheeled self propelled compactors These have three rolls a small usually split steering role in the front Two large drive rolls mounted on rear axle at both the end Static tandem compactors Tandem rolls have two equal sized rolls and are centered in line tandem These are used for the compaction of bituminous layer as they leave a smooth surface Vibratory compaction equipments
It can be divided in to following types Tandem vibratory compactors Towed vibratory compactors Towed sheep foot and tamping foot vibratory compactors Self propelled vibratory compactors Hand guided vibratory compactors Equipment for concrete mixing Concrete mixers For small jobs conc. mixers are used to mix the ingredients of the concrete Following type of concrete mixers are used in the construction Hand felt tilting drum mixers
These are smaller capacity mixers ,aggregate cement and water fed in to the drum by hand Loader fed tilting drum mixers These are larger capacity as compared to hand fed mixers These are fixed with the loading hopper operating by the wired rope for loading Reversing drum mixers This type of mixer is used on comparatively larger works The mixer drum is horizontal and it is non tilting type It has blades which work alternatively Roller pan mixers These mixers are primarily used for mortars ,the rollers and mixer blades rotate in a pan and not only mixing material but also kneading and crushing it
Tunneling equipment Selection of equipment
Selection of equipment for tunneling depends upon quantum of work involved So that the tunneling work is carried out economically,speedly and safely Muck loading Mucking is the operation of loading the broken rock or earth for removal from tunnel Mucking process can be done by the following equipments Power shovels Tractor loader Mucking machines Tunnel boring machines Tunneling is mostly done by conventional and drilling and blasting methods Working principle of tunneling these machines perform the bring operation through the rotation of the front head against the rock face The mole has circular cutter head in the front provided with fixed cutters of desired shapes The cutter head while rotating is pressed against the rock to cut or pulverize it
The tunnel boring machines are two types Single stage machine These are recommended for small dia tunnels of 3 to 6 m These machine are allowed to access change in bore hole diameter and this can be done without any change of machines
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