Important Clause and Para of IS-456 Part-1

 IS-456 is very important code for civil engineering student if you cover the code thoroughly then you never face problem either in site or class room. Here we going to discuss about important clauses of IS-456
Nominal Size Of Aggregates
5.3.3 Sizt ofAggregate
The nominal maximum size of coarse aggregate should be as large as possible within the limits specified but in no case greater than one-fourth of the minimum thickness of the member, provided that the concrete can be placed without difficulty so as to surround all reinforcement thoroughly and fill the comers of the form,
For most work, 20 mm aggregates is suitable. Where there is no restriction to the flow of concrete into sections, 40 mm or larger size may be permitted. In concrete elements with thin sections, closely spaced reinforcement or small cover, consideration should be given to the use of 10mm nominal maximum lize. Plums above 160 mm and up to any reasonable size maybe used in plain concrete work up to a maximum limit of 20 percent by volume of concrete when specifically permitted by the engineer-in-charge. The plums shall be distributed evenly and shall be not closer than 150 mm from the surface

5.3.3.1 For heavily reinforced concrete member as in the else of ribs of main beams, the nominal maximum size of the aggregate should usually be restricted to 5mm less than the minimum clear distance between the main bars or 5mm less than the minimum cover to the reinforcement whichever is smaller

5.4.1 The pH value of water shall be not less than 6

5.6  Reinforcement
The reinforcement shall be any of the following:
a) Mild steel and medium tensile steel bars conforming to IS 432 (Part I).
b) High strength deformed steel bars conforming to IS 1786.
c) Hard-drawn steel wire fabric conforming to IS 1566.
d) Structural steel conforming to Grade A of IS 2062

6.2.2 Flexural strength, f_er =0.7√f_ck  N/mm² where f_ck is the characteristic cube compressive strength of concrete in N/mm²

6.2.3.1 The modulus of elasticity of concrete can be assumed as follow

                                             E_c=5000√f_ck

           where E_c is the short term static modulus of elasticity in N/mm²

^{Age at Loading       Creep Coeficient}

     ^{7 days                            2.2}

     ^{28 days                          1.6}

      ^{1 year                            1.1}