civil engineering

Following four field tests may be carried out to ascertain roughly the quality of cement colour : colour of cement should be uniform i.e. grey colour  with a light greenish shade   Physical Properties : cement should fell smooth when touched or rubbed in between gingers  if it is felt rough ,it indicates adulteration with sand  if hand is inserted in a beg or heap of cement , it should  feel cool and not warm  if small quantity of cement is thrown  in a bucket of water , it should sink and should not float on the surface  A thin paste of cement with water should feel sticky between the fingers  if the cement contains too much of pounded clay and silt as an adulterant , the paste will give an earthy smell         3 :Persence of lumps : cement should be free form any hard lumps . such lumps are formed by                  the absorption of moisture form the atmosphere              . Any bag of cement containing such lumps should be rejected .         4: Strengt

Cement, fine aggregate and coarse aggregate (up to 38) to be used for making concrete are weighed in the ratio to be used in the field and are of hand mixing or by machine mixing             Now water is added and the entir batch mixed until the concrete appears to be homogeneous and has the desired consistency test specimens recommend are 150×150×150 mm cubes or cylinders of 150 diameter and 150 mm height  Mixed concrete is filled into the  mould in layers of 50 mm and each layer is tamped with 16 mm in diameter and 600 mm long 35 times or with a vibrator   Test specimens are stored at a temperature 27+-3 °c at 90% humidity for 24+_1/2 hour form the time of addition of water to the dry ingredients  the After this time specimens are removed  from the moulds and placed in water and kept there until taken  out just before the test                      • usually specimens are tested for 7 day  or 28 day  strength but IS code only suggest 28                         days stre

1 - water content:  Fluidity of concrete increases with water content because addition of water enhance interpartical lubrication  At site it is normal practice to increase the water content to make the concrete warkable which lowers the strength  In controlled concrete this cannot be resorted and even in uncontrolled concrete this should be the last choice  But in case if more water is added due to any reason the cement content should be proportional increased    2- mix proportions :  Aggregate cement ratio influences the workability to a large extent . The higher the ratio leaner will be the concrete. Lean concrete paste available for lubrication of per unit surface area of aggregates will be less and hence the warkability is reduced    3- shape of aggregates :      Big size aggregate  the total surface area to be wetted is less paste is required for lubricating the surface to reduce internal friction .for a given water content big size aggregate give high warkab

Warkability is defined as the property of concrete which determines the amount of useful internal wark necessary to produce full compaction  In simple words it can also be defined as the ease with which concrete can be compt 100% with regard to made of compaction and place of deposition  A concrete which can be readily compacted is said to be workable , but to merely say that warkability determines the ease of placement and the resistance to segregation is to loose a description of this vital property of concrete  Desired warkability in any particular case would depend on the means of compaction available likewise ,a warkability suitable for mass concrete is not necessary sufficient frothing , inaccessible ,or heavily reinforced section  It should be noted at warkability is different form consistency . consistency indicates fluidity or mobility  Concrete with high consistency may not be workable for a particular job and concrete having same consistency many very in warkability

1 . Stretcher :  Stretcher is the longer face of the brick ( i.e. 19 cm × 9 cm ) A course of bricks in which all the bricks are laid as stretches on facing is known as a stretcher course or stretching course  2. Header :  Header is the shorter face of the brick ( i.e. 9 cm × 9 cm ) . A course of bricks in which all the bricks are laid as headers on the facing is known as header course or heading course .  3. Lap :  Lap is the horizontal distance between the vertical joints of successive bricks courses  4 . Prepand :  Perpend  is an imaginary vertical line which includes the vertical joint separating two adjoining brick  5 . Bed :  Bed is the lower surface ( 19 cm × 9 cm ) of the brick when laid flat  6 . Closer :  closer may be of various types  closer it is a portion of a bricks with the cut made longitudinally, and is used to close up bond at the end of course  it helps in preventing the joints of successive sources ( higher or lower )

Slump test is one of most extensively used test all over the world  Slump test does not measure workability of concrete , although it gives a measure of consistency , but is very useful in detecting variation in uniformity of mix of given nominal proportions  Dimensions of the mould are, bottom diameter =200 mm top diameter =100mm and hight = 300 mm  Mould is filled in with fresh concrete in four layers , each layers of approximately one - quarter of the height of the mould and tamped with 25 strokes of the rounded end of the tamping rod ( dia 16 mm and length 600 mm)  Strokes are distributed in a uniform manner over the cross section and for the second and subsequent layers should penetrate into the underlying layer  After the top layer has been rodded, the concrete is struck off level with a trowel or the tamping rod such that the mould is exactly filled .  Mould is removed immediately by raising il slowly and carefully in a vertical direction   It allows the concrete to sub

It is a surface hardness tester for which an empirical correlation has been established between strength and rebound number It is based on the principal that the rebound of elastic mass depends on the hardness of surface against which the mass impinges  For this test, a rebound hammer also called Sachmidt hammer ,which weight about 1.8 kg and is suitable for both laboratory and field work  Is has a spring controlled hummer mass that slids on plunger with in a tubular casing . Hammer is forced against the surface of concrete bt the spring and the distance of rebound is measured on a scale which give indication of concrete strength  This test is suitable for the concrete having strength in the range of 20-26 MPa  Results are affected by facters sach as smoothness of surface size and shape of specimen , moisture condition of the concrete ,type of cement and coarse aggregate and extent of extent of carbonation of surface 

hearder bond or heading bond is the one in which all the bricks are laid as headers on the faces of walls . width of the brick are thus along the direction of the wall pattern is used only when the thickness of the wall is equal to one brick ( i.e 19 cm)  overlap is usually kept equal to half the width of bricks  This is achieved by using three - quarter brick bats in each alternate courses as quoins. This bond does not have strength to transmit pressure in the direction of the length of the wall. As such it is unsuitable for load bearing walls  It is useful for curved brick wark where the stretchers , if used would project beyond the face of the wall and would neccessitne inconvenient cutting  It is also use din construction of footings 

TRADITIONAL METHOD The traditional structure for project procurement is where the employer takes his scheme to an advanced stage with his professional team before appointing a contractor. The consultant’s role is seen as an independent one. The designer is employed to advise the client and design the work A quantity surveyor gives guidance on design costs and budgets,prepare bills of quantities, check tenders, prepare interim valuations and advises on the value of variations A consultant structural engineers might be employed either by the client, or his advisers, to design the specialist parts of the project. many major building owners and developers make use of in-house project managers to carry out all the design and financial control of the project. Project management is therefore seen as a management tool and not a procurement method. DESIGN AND BUILD METHOD The design and build arrangement is an attractive option for clients. because the contractor accepts the respon

What is a septic tank? and why we use it? The tank which Stores a waste water of House or building is called Septic Tank. Septic Tank is installed where there is no proper drainage system. In order store, the Wastage or sewage for 10-30 Days Septic tank is constructed and the same is designed. This tank is usually installed below 1.5m-1.8m from ground level. Waste water coming from sewer Pipes of the house are connected to Septic tank. Wastewater flows into the tank at one end and leaves the tank on the other end as shown in the figure. The septic tank is drained out with the help of suck out the outlet. The municipal Department suck out the wastage from Septic tank. In the early 1990’s, the tank is constructed without bottom slab below the tank. Due to seepage from Septic tank, the waste water is mixed with Fresh Water sump. To avoid this, the septic tank is cased up with the bottom slab.

A rural highway is the one , the major length of which passes through open country, excepting through isolated stretches of built - up area without changing its character . The rural roads are classified as under. National highways.- The main highway running through the length and breadth of Indian union . Connecting ports foreign highway and capitals of states and including road of strategic and millitary important , are are called national highway  State Highway - The main road of a state connecting up with the national highway or highway of adjacent states and linking the district head quarters and important cities within the states , are called state highway  Major District road - The roads traversing each district serving areas and markets and connecting these with each other or with national and state highway or railway or important navigation routes are called major District roads  Village Roads - the roads which connect villages or groups of villages with each o

1. Double headed rails ( D.H. rails) These rails wear used in the beginning  The idea was , when the head will wern out in course of time, the rail can be inverted and reused  In the lower part the inundations wear so formed that smooth running over that surface at the top was impossible , so idea got failed  2 . Bull headed rails ( B.H. rails ) :  In B. H. Rails the head was made a little thicker and stronger then the lower part  3 . Flat footed rails ( F.F. rails ) :  F.F. rails are also called vignole's rails after the name of the inventor  Bearing plates are used between the sleeper and rail at rail joints  These rails are designated by wt of rail per unit length  52 kg/ m or 52 MR and 60  kg / m or 60 MR F.F. rails are used in India  52 kg rail is suitable upto speed of 130 kmph and 60 kg rail is suitable upto speed of 160 km/h 

1. On the basic of geological origin (a) Naturat aggregate Natural aggregate are obtained by crushing form quarries of igneous , sedimentary or metamorphic rocks  Most widely used aggregate are from igneous origin  Aggregates obtained from pites or dredged from river most ofter are not clean enough or well graded to suit the quality requirement . They therefore requird sieving and washing before they can be used in concrete  (B) Artifical aggregates  Broken bricks , blast furnace slag and synthetic aggregates are artificial aggregates  Broken bricks called as brick bats are suitable for mass concreting, for example, in foundation bases. They are not used for reinforced concrete works.  Blast furnace slag aggregate is obtained from slow cooling of the slog followed by crushing .  These dense and strong aggregates as obtained are used for making precast concrete products .  The blast furnace slag aggregate has good fire resistant properties but are responsible for corros

Aggregates are the materials basically used as filler with binding material in the production of mortar and concrete  They give body to the concrete and occupy 70 to 80 percent of volume of concrete . Therefore , they exert considerable impact on the characteristics and properties of concrete  They are derived form igneous, sedimentary and metamorphic rocks or manufactured form blest furnace slag , etc.  They should be clean , hard, strong durable and graded in size to achieve utmost economy from the paste  Earlier aggregate wear considered to be chemically inert but the latest research has revealed that some of them are chemically active and also that certain types exhibit chemical bond at the interface of aggregates and cement paste  To increase the bulk density of concrete aggregates are used in two different sizes - the bigger ones known to be coarse aggregate ( grit ) and the smaller ones fine aggregate ( sand )  Coarse aggregate form the main matrix of concrete

1- LIME If Lime is present in excess , colour of bricks changes from Red to Yellow  When lime is present in lumps, it absorbs moisture , swells and causes disintegration of the bricks. Hence lime should be present in finely divided state , and lumps should be removed in the beginning itself  2- IRON PYRITES  IF IRON PYRITES ARE PRESENT IN BRICK earth , then bricks tend to oxidise and decompose during burning and may split into pieces  PYRITES discolourise the brick  3 - PEBBLES , GRAVELS , GRITS  BRICKS containing pebbles will not break regularly as desired. It does not allows clay to be mixed uniformly and thoroughly which will result in weak and porous bricks . 4 - ALKALIES  Excess of alkalies causes brick to melt and loose their shape  These causes Efflorescence- When bricks comes in contact with moisture , water is absorbed and the alkalies crystallise. On drying , the moisture evaporates , leaving behind gray or white powder deposit on the brick whic

A rural highway is the one , the major length of which passes through open country, excepting through isolated stretches of built - up area without changing its character . The rural roads are classified as under. National highways.- The main highway running through the length and breadth of Indian union . Connecting ports foreign highway and capitals of states and including road of strategic and millitary important , are are called national highway  State Highway - The main road of a state connecting up with the national highway or highway of adjacent states and linking the district head quarters and important cities within the states , are called state highway  Major District road - The roads traversing each district serving areas and markets and connecting these with each other or with national and state highway or railway or important navigation routes are called major District roads  Village Roads - the roads which connect villages or groups of villages with each other and t

Silica ( 50-60 %) :- It prevents cracking , shrinking and warping of raw bricks It imparts durability and uniform shape to bricks.  Excess of silica destroys the cohesion between particles and the brick become brittle A large  percentage of sand or uncombined silica in clay is undesirable . However . It is added to decrease shrinkage in burning and to increase the refractoriness of low alumina clays.  Alumina (20-30%) It absorbs water and imparts plasticity to the earth such that it can be moulded  It alumina is present in excess , it causes cracks in bricks on drying and becomes too hard when burnt.  Clayes having high alumina are found to be very refractory  Lime (<10%) Prevents the shrinkage on drying  It causes silica in clay to melt on burning and hence helps to bind it.  In carbonates form , lime lower the fusion  Red bricks are obtained on burning at considerably high  temperature ( more then 800°c ) and buffburning bricks are formed by increasing

1. Over - burning of bricks  If the bricks are overburnt, a soft molten mass is produced and the bricks losses their shape . Such Bricks are not used for construction works. 2 . Under - burning of bricks When brick are not burnt property, the clay is not softened because of insufficient heat and the pores are not closed . This results in higher degree of water absorption and less compressive strength  Such bricks are not recommended for construction works  3. Bloating  This defect is observed as spongy swollen mass over the surface of burned bricks.  It is caused due to the presence of excess carbonaceous matter and sulphur in brick - clay  4. Efforescence This is caused because of alkalies present in Bricks . When bricks come in contact with moisture , water is absorbed and the alkalies cry stalise. After drying grey or white powder patches appear on the bricks surface .this can be reduced by selecting proper clay materials for brick manufacturing , preventi

The estimation of the quantities of various items of a building such as earth work in excavation, concrete in foundation , bricks work in foundation and plinth, brick work in super - structure, etc may be made by the following methods : 1 . Centre line method 2 . Long and short wall method Centre line method:  In this method , the centre line length of walls in a building is multiplied by the breadth and depth of the respective item to get the total quantity of the item in case of partition or veranded walls joining with the main walls , the centre line is reduced by half of the breadth of the layer of the main wall at the same laver.                                                            Suitability: this method is especially suited for estimating the circular , hexagonal , octagonal, etc. Shaped buildings    2. Long and short wall method.  In this method , the longer walles are generally treated as long walls and the shorter or partition walls as short Wal

October 17, 2018 MASONRY DAMS The structures that are constructed across drainages ( natural or artificial ) to retain water to the required height , are known as dams. The dams which are wholly constructed with stones , are called masonry dames The following forces generally act on a dam section 1- weight of masonry acting downward 2- pressure of water acting horizontal To avoid tension in masonry , it is ensured that the resultant of the forces on the dam section , lies within the middle third of the section While analysing dam section , one should always consider a unit length of the dam . Now consider the trapezoidal dam section of unit length Let w= density of water retained         h= height of water retained         W = total weight of the masonry acting at its C-G Water pressure P= 1/2 wh2 acting at h/3 form the base The resultant R of the force P and W intersect the base at E . To locate E, take the moments of P and W about E. The resultant R may be considered to

Advantages - water Bound Macadam is superior in quality because the materials are carefully graded and the resulting mass is almost voidless compacted mass. The interlocking of aggregates particles imparts adequate strength of the materials selected for filling the voids . These ensure non entry of the plastic mstermat of the sub grade into the voids . Disadvantages- the stone pieces used in water bound macadam road are keyed together by means of sand and clay and no other cementing material  is used . The bending effects of sand and clay depends upon the pressure of moisture. When the first moving vehicle passes over a W. B. M. Road, the slurry of sand and clay is sucked out by the pneumatic wheel types , the stone pieces get disturbed and finally road surface is disintegrated . Due to this factor , the w.B.M. roads are not suitable for fast moving vehicles with wheel types . These roads are only suitable for slow moving iron wheeled traffic such as tonges , bullocks carts e

Before studying a flow net, the following terms need be clearly understood. Flow line - the line followed by percolating water through a saturated soil mass under laminar flow conditions, is called flow line . Equipotential line - the line joining the points of equal hydraulic potentials , is called an equipotential line. Flow net - the flow net work formed by a system of flow lines and equipotential lines . Is called flow net . A flow net is a pictorial representation of the pattern of flow and the dissipation of hydraulic head causing the flow in soil. Flow channel - The portion of a flow net bounded by two adjacent flow lines, is called flow channel. Field - The section of a flow channel located between two adjacent equipotential lines, is called a field  FUNDAMENTAL CHARACTERISTICS OF A FLOW NET  Flow lines and equipotential lines in a flow net intersect at right angles  All fields formed by equipotential lines and flow lines are approximate squares.  Same qu

Water bound macadam roads are constructed through the following stages as detailed below :  Preparation of sub-grade - sub grade is provided by digging up the sub soil and the level of the sub - grade is decided by subtracting the total thickness of the pavement from the finished level of the road pavement . Form the finished level of the road pavement . The sub grade is throughly compacted by rollers weighing 8 tonnes by during rolling must be made up to and brought to the grade as required.  In rocky regions the sub grade are not rolled whearas in region of clay soils, a layer to natural sand moorum or gravel , is provided over sub grade and is duly-packed. Preparation of sub-base - on the well compacted subgrade , spread 10 to 20 cm size boulders or broken stones , or over burnt bricks in layer of 15 cm thickness and total width of the sub base to be kept 60 cm wider then the pavement width , projecting 30 cm on each sides . The sub base should be compacted by a roller t

The estimation of the quantities of various items of a building such as earth work in excavation, concrete in foundation , bricks work in foundation and plinth, brick work in super - structure, etc may be made by the following methods : 1 . Centre line method 2 . Long and short wall method Centre line method:  In this method , the centre line length of walls in a building is multiplied by the breadth and depth of the respective item to get the total quantity of the item in case of partition or veranded walls joining with the main walls , the centre line is reduced by half of the breadth of the layer of the main wall at the same laver.                                                            Suitability: this method is especially suited for estimating the circular , hexagonal , octagonal, etc. Shaped buildings    2. Long and short wall method.  In this method , the longer walles are generally treated as long walls and the shorter or partition walls as short Wallas . The

The branch of physical geography which deals with the origin, distribution, and properties of water of the earth surface is called hydrology. Engineering hydrology deals with the field of hydrology which is mainly concerned with the wind and operation of engineering projects for the control and use of water . Indeed , the engineer makes use of hydrology as agriculturists , foresters, etc . do The Hydrological cycle Water goes on changing from one state to another in a cyclic order . This cycle is visualised at beginning with the evaporation of water from the oceans and lakes. The resulting vapoura are transported by the wind and under proper conditions, these vapours get condensed to form clouds which contribute to the precipitation . The precipitation which falls upon the land is disposed of in several ways as discussed below: (1) the greater part is temporarily retained in the soil on which it falls and is ultimately returned to the atmosphere either by evaporation or by t

The Indian Roads Congress ( IRC ) was established in 1934 with the following objectives :  To promote and encourage the science and practice of road building and maintenance.  To provide a forum for expression of collective opinion of its members on matters affecting roads . To promote the use of standard specifications and practices . To advise regarding education , experiment and research connected with road. To hold periodic meetings to discuss technical questions regarding road  To suggest legislation for the development , improvement And protection of roads  To suggest improved method of administration , planning, design, operation, use and maintenance of roads. To establish, furnish and maintain libraries and museums for furthering the science of road making