Posts

What is the purpose of keeping tremie pipe’s tip immersed in freshly-placed concrete for about 1m in underwater concreting?

  What is the purpose of keeping tremie pipe’s tip immersed in freshly-placed concrete for about 1m in underwater concreting? The size of tremie pipe is about 300mm with sections having flange couplings fitted with gasket to prevent water leakage. The tremie pipe should be closed initially to prevent water from entering the pipe. It should be designed with sufficient thickness and weight so that it would not be buoyant when empty inside water. The placement of tremie concrete is commenced by putting the closed pipe underwater to the location for concreting, followed by partial filling of tremie pipe with concrete. In order to have tremie concrete flowed out of the pipe, it is necessary to fill the pipe with concrete of sufficient height to overcome the water pressure and frictional head. After that the tremie pipe is raised about 150mm to allow concrete to flow out. To enhance sufficient bonding, each succeeding layer of concrete should be placed before the preceding layer has reached
Post a Comment
Read more

SPECIFICATION FOR READY MIX CONCRETE SUPPLY (RMC)..WHAT IS THE REASONS BEHIND THE COLLAPSE SLUMP OF CONCRETE??

  SPECIFICATION FOR READY MIX CONCRETE SUPPLY (RMC)   A) Technical Specifications.   ➢    Concrete Mix designs of all grades to be used along with past cube results/ trial results shall be approved. Any change in CMD subsequently shall also be approved. ➢     Max. cement content shall not exceed 450 Kg/Cum . And W/B ratio shall not be less than 0.32 . Use of Fly ash is must for all grades of concrete. ➢     No Mahad Sand, Crusher waste product, stone dust to be used. Only Vaitarna sand or Crushed sand to be used. ➢     Cement slurry in starting will be brought by RMC supplier. Cement slurry shall not be pumped into pouring place since w/c ratio is higher than required. Acceptance criteria for concrete at the time of arrival on site.   ➢     Max. slump permitted at the time of arrival = 125mm . No collapse slump will be accepted. Slump at Plant will be 150mm. to 160mm. Slump Cone and Cube Moulds must be kept at Batching Plant also, for checking concrete. No
Post a Comment
Read more

WHAT IS HOUSE WIRING SYSTEM ?? ISI RULES FOR WIRING

Image
SYSTEMS OF WIRING • Tree System • Distribution System Tree System: • This system is not used in installation purpose. It is generally used for temporary connections nowadays. In this system branch circuits are tapped from the mains at required places. • Advantages: Less cost. • Disadvantages: Appearance is poor. • Fault location is difficult. • Large voltage drops. Distribution System: • This system is used widely now a days and is used for indoor wiring in buildings. In this system, mains are taken to one or more distribution centres and connected to the distribution boards. From these distribution boards connections are taken to branch circuits. In this system no joints are required and is systematic. • Advantages: Appearance is Good. • Fault location is easy. • Each circuit is separately protected by a Fuse or MCB. • Replacement of Fuse or MCB is easy. • The system is simple and capable of further extensions. • Disadvantages: It is costlier than the Tree System. ISI RULES FOR WIRING
Post a Comment
Read more

HOW ELECTRICITY GENERATED ?? WHAT IS TRANSFORMER??

Image
HOW ELECTRICITY IS GENERATED Power Generation: The bulk electricity is generated in generating station/power plants. The main machine which generates electricity is Generator. A generator is a machine which converts mechanical energy into electrical energy. Types of power generating stations: (1) Hydro-power generation. (2) Steam power generation (3) Gas turbine power plant. (4) Diesel power station (5) Nuclear power station. Main Components of Power Generation: (1) Prime mover: This converts energy from some form to mechanical energy. This is normally coupled to the Alternator for rotating. (2)  Alternator: This converts Mechanical energy into Electrical energy. The output of alternator is delivered to the busbars through transformers, breakers and later transmitted through transmission lines for distribution. WHAT IS A TRANSFORMER • The transformer may be defined as static piece (No rotating part) of apparatus which converts Electrical Power from one circuit to the other circuits a
Post a Comment
Read more

WHAT IS ELECTRICITY??WHAT IS CURRENT??

Image
WHAT IS ELECTRICITY? 1)      Electricity is an Energy. 2)      Energy which does the work      Facts about Electricity: (i) It travels at the speed of 297841 Km/sec . (ii) In India, voltage generation is A.C and is at 11KV. (iii) The generation is at 50 Hz . (iv) Shock - AC Voltage - 325 V DC Voltage - Same V (v) All equipments are connected in parallel. (vi) It cannot be seen, only the effects of electricity can be seen/felt. (vii) Current always takes shortest route to complete the circuit.      Magic Triangle of Electricity:        SOME IMPORTANT TERMS/DEFINITIONS: • Voltage : It is the potential difference between two points. • Current: It is flow of Electrons. • Frequency: No. of Cycles/Second. • Resistance: This apposes flow of current. • Conductor: This offers least resistance to flow of current. • Insulators: This offers maximum resistance to flow of current.   WHAT IS CURRENT?? • Flow of electrons in any conductor is called Current. The unit of current is Ampere. • It is
Post a Comment
Read more

WHAT IS STEEL DOKA SHUTTERING SYSTEM?? ADVANTAGES OF STEEL DOKA SHUTTERING

Image
STEEL DOKA SHUTTERING Steel Doka system can be used for  ordinary as well as for flat slab.  A)     ADVANTAGES OF USING STEEL DOKA SHUTTERING SYSTEM 1)      Better finish. 2)      Ease of erection and removal of shuttering. 3)      Long lasting. (many repetitions ) 4)      Can be used for any slab thickness. 5)      Engineered design calculations. 6)      Components of system can be used for other purpose also. 7)      Easy checking. 8)      Controlled deflection. B)        STEEL DOKA SYSTEM CONSIST OF, 1)      Film face Plywood 12mm thick 2)      M.S. 4 way head 3)      ISLB 100 x 50 mm Joist, 2.2m long 4)      ISLB 100 x 50 mm Bearer, 1.5m long. 5)      G.I Acrow Telescopic Prop. (2.44m – 4m). 6)      G.I. Tripods. 7)      M.S. Bracing pipes. C)      General arrangement of system is as shown in picture. Plywood is supported by joist (ISLB 100x50) Joist is supported by Bearer (ISLB 100x50) Bearer is supported by Acrow props. D)    SEQUENCE OF ERECTIONS      In case of Grade slab, one
Post a Comment
Read more

HOW DO YOU INSTALL ELECTRICAL CONDUIT ON CONCRETE SLAB???WHAT IS THE SPECIFICATION FOR SLAB CONDUITING???

Image
SLAB CONDUITING 1)   Preparation of slab conduiting drawing by electrical contractor. 2)   Verification by electrical dept. and approval by Engg dept authorized signatory. 3)   Slab conduiting on site as per approved plan. Accessories for Slab Conduiting 1)    PVC Pipes. 2)   Junction Boxes (1 Way to 4 Ways) 3)   Fan Junction Box 4)   Couplers 5)   Reducers 6)   Bends 7)   PVC Cement Solvent 8)   Paint STANDARD SPECIFICATION FOR SLAB CONDUITING 1)  Conduiting should be done only after slab re-bars are laid and after fixing of PVC cover. 2)  Gap between adjacent conduits should be min. 25mm. 3)  Conduits should not pass through RCC Column. 4)  Conduit drops should be on wall face only. 5)  Conduits should not be in cover zone of re-bars. 6)  Light / Fan points should be painted for easy identification on slab surface soffit (slab shuttering). 7)  Conduits & Junction openings to be sealed to avoid choking and should be touching shuttering. 8)  Light / Fan / TV / Tel. / Bracket light
Post a Comment
Read more

WHAT IS EARTHING??? WHY IT IS DONE???WHAT IS GOOD EARTHING???

Image
WHAT IS EARTHING AND WHY IT IS DONE  Earthing is an electrode embedded in the soil to provide path to the leakage current.  Earthing is provided to : a) To save Human life from shock and also probability of death. b) To Protect Large Buildings from Atmospheric Lightening. c) To protect all machines and to maintain line voltage.   What is a Good Earthing • A Good Earthing is that earthing which gives very low resistance to the flow of heavy current. • The Potential at earth is Zero   TYPES OF EARTHING  1. Pipe Earthing 2. Plate Earthing HOW DO WE GET A SHOCK Human Body is a conductor. When a Live Wire touches the human body, current completes its path through body and earth resulting in a shock. The muscular functions of the body are paralyzed due to the current action on the nervous system causing breathing problems, severe burns, and resulting in death. PRECAUTIONS TO BE TAKEN TO PREVENT ELECTRIC SHOCK : • Care in handling all electrical apparatus and equipment. • Never use appliances
Post a Comment
Read more