7 March 2023 admin Uncategorised Leave a comment

Ingredients of Cement

INGREDIENT PERCENTAGE USE EXCESS LACK LIME 60-65 STRENGTH Unsound, disintegration of cement. Low strength, decrease setting time SILICA 17-25 STRENGTH High strength, increase setting time Low strength, decrease setting time ALUMINA 3-8 SETTING TIME Decrease setting time, decrease temperature of clinker Increase setting time IRON OXIDE 0.5-6 COLOUR Reddish color Low hardness MAGNESIA 0.1-3 COLOUR Yellowish color Low hardness GYPSUM 1-3 SETTING TIME Increases setting time Decreases setting time SULPHUR 1-3 SOUNDNESS Unsound Unsound ALKALI 0.1-1 Efflorescence

7 March 2023 admin Uncategorised Leave a comment

Differences between impulse and reaction turbine

IMPLUSE TURBINE REACTION TURBINE The potential energy of water is completely converted to kinetic energy while striking. The potential energy of water is partially converted to kinetic energy while striking. The pressure of jet striking is atmospheric. The pressure of jet striking is less than atmospheric It is not connected directly with pipe. It is connected directly with pipe. Ex: Pelton wheel turbine Ex: Francis Turbine Draft tube is not required. Draft tube is required in tailrace.

1 January 2023 admin Uncategorised Leave a comment

Difference between Flushing and Sluicing of Reservoir

Flushing Sluicing Flushing is done to remove sediment during high flood. Sluicing is done to remove sediment during plant operation. Intake structure aren’t operational during flushing as water level cannot be maintained. Intake structures can remain operational during sluicing as water level can be maintained. Outlet discharge is controlled by outlet structure. Outlet discharge is control by water level. Flushing has retrogressive erosion downstream. Retrogressive erosion doesn’t occur for sluicing. Flushing is done through bottom outlet. Sluicing outlet can be […]

10 October 2022 admin Uncategorised Leave a comment

Components of Tunnel

Chainage The length along the longitudinal direction of tunnel Crown The top portion of tunnel is crown. It can be circular,semi-circular or rectangular in shape. Side/Wall The side portion of tunnel. It is generally vertical. Bench The bottom part of tunnel left after the excavation of heading is said to be bench. Excavation of face in done in multiple step for large cross sectional area. Invert The lower portion of tunnel Portal The entrance of tunnel is portal. Heavy support […]

28 June 2022 admin Construction, Project Management Leave a comment

Difference between CPM and PERT Method in project management

CPM PERT CPM stands for critical path method PERT stands for program evaluation and review technique It is activity based method It is event based method It is used in repetitive works like construction It is used in non-repetitive works like research It is deterministic method with single time estimate It is probabilistic method with three time estimate namely optimistic, most probable and pessimistic It is concerned with control of cost and time It is only concerned with control of […]

17 May 2022 admin Hydrology, Hydropower One comment

Snyder’s Unit Hydrograph

To Plot snyder’s unit hydrograph we need value of basin lag (tpr), time base(tb) , width of hydrograph at 50% discharge(W50) , width of hydrograph at 75% discharge(W75) The peak time is distance from centroid of effective rainfall to peak of the discharge. where, tp = Peaking time in standard condition tpr = Basin lag in general condition C1=0.75 Ct=Watershed factor where, qp is peak discharge per unit catchment area Cp=Watershed factor C2=2.75 C3=5.56 The width of hydrograph at 50% […]

16 May 2022 admin Construction, Construction Material, Quantity Estimate Leave a comment

Dry weight of sand mortar

Mortar is heterogeneous mixture of cement sand and water. Water reacts chemically with cement ingredients resulting in hydration of cement and fills the voids between cement and sand. As water is added to dry cement sand mixture the volume reduced. For quantity estimate of cement sand mortar the wet mortar’s volume should be increased to account for Water required for hydration. Water required filling of voids. Dry weight of mortar = Wet weight of mortar * 1.33

16 May 2022 admin Hydropower Leave a comment