amardeep singh sohal

to find the wt per mtr of steel bar • Take the dia of the bar • Divide the dia by 2 • Square the obtained value • Divide the value by 4 • Mark the point before last digit Example 1 IF THE DIA IS 16 MM DIVIDE BY 2 16/2 = 8 SQUARE THE OBTAINED VALUE 82 = 64 DIVIDE THE VALUE BY 4 64/4 = 16 MARK THE POINT BEFORE LAST DIGIT 1.6 kg/m Example 2 IF THE DIA IS 12 MM DIVIDE BY 2 12/2 = 6 SQUARE THE OBTAINED VALUE 62 = 36 DIVIDE THE VALUE BY 4 36/4 = 9 MARK THE POINT BEFORE LAST DIGIT 0.9 kg/m

Review of Laminated Elastometric Bearing Pad (AASHTO M251 & BS 5400: Part 9) Steel-Reinforced Elastometric Bearings – Method B A. Allowable Delamination compressive Stress: 1. Shear Modulus (G) = 130 ~ 199 psi (Say Use 150 psi = 1.03 MPa) 2. Hardness -- Use 50 Durometer (Between 50 ~ 60 on Shore A scale) 3. Compressive Stress (AASHTO 14.7.5.3.2) In any elastometric bearing layer, the average allowable compressive stress at the service limit state shall satisfy: • For bearing subject to shear deformation: S: Shape factor (8.5 Service DL per bearing: DL = 300 kN (67.443 kips) Service LL per bearing: LL = 500 kN (112.404 kips) Existing L= 600mm W= 200 mm c= (DL+LL) / LW = 800*1000N/ (600x200)mm2 =6.67 MPa = 1 ksi hri: 6.4mm hrc: 6.3mm so, S=600*200/(2*6.4*(600+200))=11.7 (actual) c=6.67 MPa B. Determine Bearing Pad size: 4. n: number of interior layers = 6 Reinforcing steel shims : hs= 2.7mm 8. Bearing pad Thickness check: ...

Specific Gravity Specific gravity is the ratio of density of a substance compared to the density of fresh water at 4°C (39° F). At this temperature the density of water is at its greatest value and equal 1 g/mL. Since specific gravity is a ratio, so it has no units. An object will float in water if its density is less than the density of water and sink if its density is greater that that of water. Similarly, an object with specific gravity less than 1 will float and those with a specific gravity greater than one will sink. Specific gravity values for a few common substances are: Au, 19.3; mercury, 13.6; alcohol, 0.7893; benzene, 0.8786. Note that since water has a density of 1 g/cm3, the specific gravity is the same as the density of the material measured in g/cm3. The Discovery of Specific Gravity The discovery of specific gravity makes for an interesting story. Sometime around 250 B.C., the Greek mathematician Archimedes was given the task of determining whether a craftsman had d...

Drum Rotations of Transit Mixer/ Agitator Another test method is to count the actual rotation of the ready mix truck drum rotations. Once the mix and water are placed in the drum the load should be delivered and discharged before the drum has revolved 300 times. Over-mixing concrete damages the quality of the concrete. Over-mixing may: • Grind the aggregate into smaller pieces, • Increase the temperature of the mix, • Separate the aggregates from the cement paste • Lower the slump, • Decrease air entrainment, and • Decrease the strength of the concrete. Also, over-mixing puts needless wear on the drum and blades of the transit mixer Time An important quality control test for concrete is to identify the length of time from when water is added to the mixture until the mixture is poured. The batch ticket has the elapsed time recorded between the mixture and the placement. Concrete begins to stiffen as soon as the cement and water are mixed. However, the degree of stiffening th...

All reinforcement shall be furnished in full lengths as indicated on the drawing. No splicing of bars, except where shown on the drawing, shall be permitted without approval of the Engineer. Where practicable, overlapping bars shall not touch each other, and shall be kept apart by 25 mm or 1.25 times the maximum size of coarse aggregate, whichever is greater . If this is not feasible, overlapping bars shall be bound with annealed steel binding wire not less than 1 mm diameter and twisted tight in such a manner as to maintain minimum clear cover to the reinforcement from the concrete surface. Lapped splices shall be staggered or located at points, along the span where stresses are low.

Concrete shall be transported and placed as near as practicable to its final position, so that no contamination, segregation or loss of its constituent materials takes place. Concrete shall not be freely dropped into place from a height exceeding 1.5 mtr

When it is necessary to deposit concrete under water, the methods, equipment, materials and proportions of mix to be used shall be got approved from the Engineer before any work is started. Concrete shall contain 10 percent more cement than that required for the same mix placed in the dry to compensate the loss due to wash. Concrete shall not be placed in water having a temperature below 5oC. The temperature of the concrete, when deposited, shall not be less than 16oC, nor more than 40oC. Coffer dams or forms shall be sufficiently tight to ensure still water conditions, if practicable, and in any case to reduce the flow of water to less than 3 m per minute through the space into which concrete is to be deposited. Coffer dams or forms in still water shall be sufficiently tight to prevent loss of mortar through the joints in the walls. Pumping shall not be done while concrete is being placed, or until 24 hours thereafter. To minimise the formation of laitance, care shall be exercised ...

                                              By hand the concrete cube should be filled by 3 layers 35 tampings on each layer by rod 16 mm dia The no of tampings are between 100 – 105 while preparing the concrete cube the no of tampings divides the no of layers                       For eg cube is casted in 3 layers  ( 150 mm cubes )                       105/3                 =                  ...

Aggregates occupy ¾ space in the concrete mass and have following functions ( a ) provide a filler for concreting material ( b) provides mass to the concrete and reduce volume changes while setting and hardening of concrete.  ( c ) the rest ¼ is occupied by the paste ( water + cement ) binder which is an active component of concrete and having following functions:  ( a)  it fills the voids between aggregates ( b ) it gives strength to hardened concrete             The Reinforced Concrete ( R.C.C.) , the steel and concrete forms a very good combination because the co-eff of expansion of concrete and steel are nearly equal.             Concrete has low tensile strength & hence cracks easily .Therefore  concrete is to be reinforced with mild steel bars, high tensile steel bars or mesh .             Co...