Basics of Cement concrete

Basics of Cement concrete.    It get by mixing the following four ingredients in predetermined proportions. Cement.   Sand,  Gravel and  Water   Plastic mass  First Step - In a Concrete mixer when we mix the above four ingredients .  Second step - We get the plastic mass of concrete. To get a desired shape of concrete we poured the mix into a define shape of a mould.The plastic mass poured in Moulds, standing into hard solid mass.   Setting Time  The chemical reaction of cement, and in the mix, is slow  Chemical reaction requires time and favorable temperature for its completion.  This time, known as setting time. This Setting time  divided into three distinct phases.   The first phase.   The first phase is known as initial setting time.  It  requires from 30 minutes to about 60 minutes for completion.  During this phase, the mixed concrete decreases its plasticity  Mixed concrete develops pronounced resistance to flow.   The second phase  The second phase, known as final setting time.  It  may vary ·between 5 to 6…

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Read more about the article Meter and non meter fall
meter and non meter fall

Meter and non meter fall

METER AND NON-METER FALLS The falls may be divided into following two types: 1. Meter falls 2. Non-meter falls. 1. Meter Falls. The falls which can be used to measure the discharge flowing over them, are known as meter falls. Such falls must have broad crest so that the discharge coefficient remains constant under variable head. Glacis type falls are most suitable as meter falls. If section of the channel at the site of the fall has to be flumed. From economic considerations, smooth U/S transition. Should be provided to avoid turbulences and also to maintain accurate stage-discharge relationship. 2. Non-meter Falls. The falls which cannot be use to measure the discharge passing through them, are known as non-meter falls. Vertical drop falls cannot be used as meter falls. Some vacuum is developed under the nappe of falling water, which causes non-uniform flow conditions.

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Read more about the article Canal Regulation Works
Canal Regulation Works

Canal Regulation Works

INTRODUCTION To exercise control on discharge, full supply level, velocity of flow, silting etc. various masonry or concrete structures have to be constructed over the canals. All these structures are know Canal Regulation Works. Main Regulation works may be listed as follows: 1. Canal falls 2. Head regulator 3. Cross regulator 4. Metres and Flumes 5. Canal escapes. Canal outlets, also come under the category of regulation works, but they have been discussed separately.

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Elementor #5517

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Read more about the article CANAL FALLS
CANAL FALLS

CANAL FALLS

CANAL FALLS Why Falls are Provided When natural slope of the country is steeper than the designed longitudinal slope of the irrigation canal. The falls have to be provided. If falls are not provided, the canals run so much in filling. That it will be almost impossible to even construct the canals. If canal is constructed very much in filling. It will be a constant danger to the adjoining people, and also it will be impossible to mantain it. For example, let slope of a particular canal be say 1 in 5000 and general slope of the ground say 1 in 2500. If canal bed at the start i.e. zero distance, is say 1 m in cutting. The bed of canal will just coincide with ground level at a distance of 5000 m and thereafter. The bed of the canal will come in filling. The fill of the canal will…

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Read more about the article Classification of falls
Classification of falls

Classification of falls

CLASSIFICATION OF FALLS The falls can be classified into the following four categories according to the approach conditions. 1. Falls which maintain relation between depth and discharge. 2. Falls which maintain level of U/S water constant. 3. Combination of fall and regulator. 4. Miscellaneous falls. 1. Falls in which D-Q relationship is maintained. In such falls there is neither drawdown nor heading up of water on U/S side. The Depth-discharge relationship for the channel is maintained. Trapezoidal notch falls and low crested rectangular notch falls, fall under this category. 2. Falls which maintain fixed F.S.L. on the U/S side of the fall. Siphon fall or Siphon spillway high crested weir fall are the falls which fulfil this condition. Such falls cause silting on U/S side. Such falls are necessary under following circumstances. (i) When a sub-channel has to take off at some distance U/S of the fall. (ii) When Hydro-electricity…

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Type Membrane Lining

Buried and Protected type Membrane Lining These linings are such lining in which a waterproof thin membrane is place on the prepare subgrade. Thereafter it is covered by a protective layer of earth or gravel. The protective layer provides protection to the lining against damage due to outside effects. Membrane itself provides imperviousness. The commonly used buried membranes may be: 1. Sprayed asphaltic lining. In this hot asphalt is sprayed on the subgrade which acts as water proofing barrier. 2. Prefabricated asphaltic membrane lining. In this, asphalt lined papers, clothes, mats etc. are used to put a barrier against seepage. All these fabrications are available in marked in form of rolls. The membrane is laid on smooth well prepared subgrade and covered with a fine soil or earth. 3. Plastic or rubber membrane lining. In this case, plastic or synthetic rubber membrane is used as water proofing membrane. Out of…

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Read more about the article Lined Canals and Their Design
Lined Canals and Their Design

Lined Canals and Their Design

INTRODUCTION Canal lining is a treatment given to the canal bed and banks, so as to render the canal section impervious. Since imperviousness of the canal section is achieved mostly by making canal section pucca. Either by cement concrete or bricks, the lined canals are also sometimes know pucca canals. Lined canals are mostly referred to as pucca canals. It has been estimated that seepage losses in irrigation canals. May amount from 30% to 50% of the water admitted in the canals at diversion headworks. This much loss of water in unlined channels cannot be afforded. As resources of water in India are limited in relation to irrigable area available. Hence in order to reduce or rather eliminate the seepage losses, lining of canals is the need of the hour. Advantages of Lining Following are the benefits of lined canals: Seepage losses are practically eliminated or reduced to minimum. Maintenance…

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Read more about the article Essential properties of a good lining
ESSENTIAL PROPERTIES OF A GOOD LINING

Essential properties of a good lining

ESSENTIAL PROPERTIES OF A GOOD LINING Following are the essential properties of a good lining: The lining should be completely water tight. The rugosity coefficient of the lining material should be low, so as to make the section more efficient, hydraulically. The lining should be strong and durable. Initial cost of lining and its subsequent maintenance cost should be low. The lining should not get damaged by tramping of cattles. It should resist growth of weeds and attack of burrowing animals. Lining should not get damaged when flow in the canal is stopped. TYPES OF LINING The linings may be classified under the following four heads: Hard surface lining Buried and protected type membrane lining Earth lining Porous type lining, Each class of lining is discussed in details one by one. Hard Surface Lining The following types of linings come under this category: Cement concrete lining Shot-crete lining Precast concrete…

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