Civil Engineering

  TRANSPORTING, PLACING, COMPACTION AND CURING OF CONCRETE-AS PER IS-456-2000 *Transporting and Handling 1.      After mixing, concrete shall be transported to the formwork as rapidly as possible by methods which will prevent the segregation or loss of any of the ingredients or ingress of foreign matter or water and maintaining the required workability. *Placing of Concrete- 1.      The concrete shall he placed and compacted before initial setting of concrete commences and should not be subsequently disturbed. 2.        Methods of placing should be such as to preclude segregation . 3.        Care should be taken to avoid displacement of reinforcement or movement of formwork. 4.        As a general guidance, the maximum permissible free fall of concrete may be taken as 1.5 m. *Compaction of Concrete- 1.      Concrete should he t...

  REINFORCEMENT SPLICING – AS PER IS 456 -2000 It Is recommended that splices (Lap) in flexural member should not be at sections where the bending moment is more than 50 percent of the moment of resistance; and not more than half the bars shall be spliced at a section. Where more than one-half of the bars are spliced at a section or where splices are made at point of maximum stress, special precaution shall be taken, such as increasing the length of lap and/or using spirals or closely-spaced stirrups around the length of the splice. Notes:- 1.      Lap splices shall not be used for bars larger than 36 mm ; for larger diameters, bars may be welded; in cases where welding is not practicable, lapping of bars larger than 36 mm may be permitted, in which case additional spirals should be provided around the lapped bars. 2.      Lap splices shall be considered as staggered if the centre to centre distance of the splices is not less th...

  DEVELOPMENT LENGTH - AS PER IS-456-2000 *The development length L d. is given by                     𝑳𝒅 = 𝝓𝝈𝒔/ 𝟒𝝉𝒃𝒅 Where,         𝝓  = nominal diameter of the bar,     𝝈𝒔 = stress in bar at the section considered at design load    𝝉𝒃𝒅 =design bond stress NOTES:-  1.       The development length includes anchorage values of hooks in tension reinforcement.  2.       Design bond stress in limit state method for plain bars in tension shall be as below Grade of concrete M20   M25 M30 M35 M45 & Above Design bond stress,   N/mm2 1.2 1.4 1.5 1.7 1.9 3.       For deformed bars conforming t...

WORKABILITY OF CONCRETE - AS PER IS-456-2000 The concrete mix proportions chosen should be such that the concrete is of adequate workability for the placing conditions of the concrete and can properly be compacted with the means available. Placing Conditions Degree of Workability Slump(mm) Blinding concrete; Shallow sections & Pavements using pavers   Very low In the ‘very low’ category of workability where strict control is necessary, for example pavement quality concrete, measurement of workability by determination of compacting factor will be more appropriate than slump ( see IS 1199 ) and a value of compacting factor of 0.75 to 0.80 is suggested. Mass concrete, Lightly reinforced sections in slabs, beams, walls, columns, Floors; Hand placed pavements; Canal lining; Strip footings     Low     25-75 Heavily reinforced sections in s...

  As Per SP-27-1987-Removing mortar from masonry joints to provide suitable key for the plastering and pointing.

  What is Hacking? As Per SP-27-1987-The roughing of solid backgrounds, by hand or mechanical methods, to provide a suitable key.