RCC25 PRACTICAL TIPS2IS 456: 2008TIP# 1: Use of Cement type should be judicious. High alumina or ulphate cement may only be used under special circumstances.Reason:Sulphate Resistant Cement has low content of C3A to reduce the infuence of Sulphate attack. In an environment with both Sulphates and Chlorides, the C3A in the cement reacts preferentiall with the Sulphates and enou!h C3A is left to bind the chlorides.3TIP# !: "irect tensile strength of concrete is e#ual to about $ to 1%& of the compressi'e strength. TIP# (: The strength of concrete in PU)* H*+) has been reported to be in the range of 1, to !,& of its compressi'e strength.TIP# -: +s the coefficient of thermal e.pansion of both concrete and steel are in the same range/ steel is used as reinforcing material for )CC.Co-efficient of thermal expansionConcrete 6x10^-6 mm/mm/C to 12x10^-6 mm/mm/CSteel 12x10^-6mm/mm/C"TIP# %: The 0ater content normally ranges from 11, to !!, liters per cubic m in concrete mi..TIP# 1: The ratio of sand to stone2chips is 1:! or ,.(%:1%.TIP# $: +brasi'e resistance of concrete increases 0ith: Compressi'e strength and Use of aggregate ha'ing lo0 abrasion#TIP# 3: Crac4ing le'els depend on: Tensile strength of concrete. Clear co'er "iameter of rebar )ate of corrosionTIP# 5: Corrosion ta4es place only in the presence of: 6oisture 7 8.ygenTIP# 1,: 9hen concrete is subject to sustained compressi'e loading / its deformation 4eeps increasing 0ith time and this time dependent component :e.cluding the strains introduced by shrin4age and temperature 'ariations; of the total strain is termed as Creep.$TIP# 11: "etrimental results in )C structures due to creep: Increased deflection of beams and slabs Increased deflection of slender columns :possibly leading to buc4ling; c ratio is high +ir entertainment is high Temperature :causing moisture loss; is high +ggregate content is lo0 )elati'e humidity is lo0 i?e > thic4ness of the member is small =oading occurs at an early age 7 =oading is sustained o'er a long periodTIP# 1(: Curing of concrete should be continuous. +lternate drying and 0et conditions 0ill cause alternating 'olume changes in concrete.&TIP# 1-: trength of concrete for 'arious period are:"uration trength 7 days 2/3 of 2day stren!th 2 days 1"0 2 months 1"1 #$a%le &"1' (roperties of Concrete %y )dam*e+ille, 3 months 1"16 6 months 1"2 12 months 1"2-TIP# 1%: The minimum grade of concrete shall be 6!,. :Clause %.! of I 1(5!,:155(;'TIP# 11: If a column or a post is added at the free end of a cantile'er beam or slab/ crac4s 0ill de'elop at the ends.)eason: .t no lon!er %eha+es as a cantile+er /hen a /all or col0mn is added %elo/ the free end"Cantilever BeamBeamBending Moment curveWall/ columnCantilever Beam with Column below free endBeamBending Moment curveWall/ column()TIP# 1$: + first class bric4 should not absorb 0ater more than !,& of its o0n dry 0eight after !- hours immersion in cold 0ater.TIP# 13: + first class bric4 should ha'e a minimum crushing strength of 1,% 4g> s#. cmTIP# 15: *.cess of +lumina and ilica in the clay ma4es the bric4 crac4 and 0rap on drying.TIP# !,: The permissible shrin4age of ordinary concrete is ,.( to ,.1 mm>m.((TIP# !1: The permissible limit for solids in 0ater used for concrete mi. as per I-%1:!,,, are:1r!anic 200m!/l.nor!anic3000m!/lS0lphates #as S13, -00m!/lChlorides #as Cl, 2000m!/l for concrete not containin! em%edded steel&00m!/l for 2CC /or3sS0spended matter 2000m!/l(2TIP# !!: @orrough estimation of reinforcement steel in construction projects follo0ing thumb rules may be adopted:Sla% &0 to 0 3!/m^3 of concrete4eams 100 to 1&0 3!/m^3 of concreteCol0mns 1&0 to 22& 3!/m^3 of concrete5ootin! sla% 0 3!/m^3 of concreteS0nshade &0 3!/m^3 of concrete6intels 0 3!/m^3 of concrete(3TIP# !(: To find the 0eight of the steel bars per meter the formula is:,.,,111! A "iameter B! :in 4g>m;*.ample:7ei!ht of 2& mm %ar/ m 8 0"006162 9 2&^2 8 3"& 3!/mTIP# !-: It is better to pro'ide a ma. spacing of !,,mm :3C; for main bars and !%,mm :1,C; in order to control the crac4 0idth and spacing.("TIP# !%: ymmetrical framed structure should be preferred for proper load transfer. +ny de'iation should be ta4en care by detailed design and dra0ings.BEAMSCOLUMNSFOUNDATIONSOILSLABS